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drgn/libdrgn/linux_kernel.c

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Update copyright headers to Facebook and add missing headers drgn was originally my side project, but for awhile now it's also been my work project. Update the copyright headers to reflect this, and add a copyright header to various files that were missing it.
2020-05-15 23:13:02 +01:00
// Copyright (c) Facebook, Inc. and its affiliates.
Use GPL-3.0-or-later license identifier instead of GPL-3.0+ Apparently the latter is deprecated and the former is preferred. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-04-03 09:10:35 +01:00
// SPDX-License-Identifier: GPL-3.0-or-later
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
#include <dirent.h>
Clean up #includes with include-what-you-use I recently hit a couple of CI failures caused by relying on transitive includes that weren't always present. include-what-you-use is a Clang-based tool that helps with this. It's a bit finicky and noisy, so this adds scripts/iwyu.py to make running it more convenient (but not reliable enough to automate it in Travis). This cleans up all reasonable include-what-you-use warnings and reorganizes a few header files. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-24 00:02:02 +01:00
#include <elf.h>
#include <gelf.h>
#include <libelf.h>
#include <stdio.h>
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
#include <errno.h>
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
#include <fcntl.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
#include "binary_buffer.h"
libdrgn: split bit operations into their own header And improve their documentation. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-10 01:17:10 +01:00
#include "bitops.h"
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
#include "debug_info.h"
Clean up #includes with include-what-you-use I recently hit a couple of CI failures caused by relying on transitive includes that weren't always present. include-what-you-use is a Clang-based tool that helps with this. It's a bit finicky and noisy, so this adds scripts/iwyu.py to make running it more convenient (but not reliable enough to automate it in Travis). This cleans up all reasonable include-what-you-use warnings and reorganizes a few header files. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-24 00:02:02 +01:00
#include "drgn.h"
#include "error.h"
#include "hash_table.h"
libdrgn: add page table walker kernel memory reader Now that we can walk page tables, we can use it in a memory reader that reads kernel memory via the kernel page table. This means that we don't need libkdumpfile for ELF vmcores anymore (although I'll keep the functionality around until this code has been validated more).
2020-05-06 08:35:29 +01:00
#include "helpers.h"
Clean up #includes with include-what-you-use I recently hit a couple of CI failures caused by relying on transitive includes that weren't always present. include-what-you-use is a Clang-based tool that helps with this. It's a bit finicky and noisy, so this adds scripts/iwyu.py to make running it more convenient (but not reliable enough to automate it in Travis). This cleans up all reasonable include-what-you-use warnings and reorganizes a few header files. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-24 00:02:02 +01:00
#include "language.h"
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
#include "linux_kernel.h"
Clean up #includes with include-what-you-use I recently hit a couple of CI failures caused by relying on transitive includes that weren't always present. include-what-you-use is a Clang-based tool that helps with this. It's a bit finicky and noisy, so this adds scripts/iwyu.py to make running it more convenient (but not reliable enough to automate it in Travis). This cleans up all reasonable include-what-you-use warnings and reorganizes a few header files. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-24 00:02:02 +01:00
#include "platform.h"
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
#include "program.h"
Clean up #includes with include-what-you-use I recently hit a couple of CI failures caused by relying on transitive includes that weren't always present. include-what-you-use is a Clang-based tool that helps with this. It's a bit finicky and noisy, so this adds scripts/iwyu.py to make running it more convenient (but not reliable enough to automate it in Travis). This cleans up all reasonable include-what-you-use warnings and reorganizes a few header files. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-24 00:02:02 +01:00
#include "type.h"
#include "util.h"
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: add page table walker kernel memory reader Now that we can walk page tables, we can use it in a memory reader that reads kernel memory via the kernel page table. This means that we don't need libkdumpfile for ELF vmcores anymore (although I'll keep the functionality around until this code has been validated more).
2020-05-06 08:35:29 +01:00
struct drgn_error *read_memory_via_pgtable(void *buf, uint64_t address,
size_t count, uint64_t offset,
void *arg, bool physical)
{
struct drgn_program *prog = arg;
return linux_helper_read_vm(prog, prog->vmcoreinfo.swapper_pg_dir,
address, buf, count);
}
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
static inline bool linematch(const char **line, const char *prefix)
{
size_t len = strlen(prefix);
if (strncmp(*line, prefix, len) == 0) {
*line += len;
return true;
} else {
return false;
}
}
static struct drgn_error *line_to_u64(const char *line, const char *newline,
int base, uint64_t *ret)
{
unsigned long long value;
char *end;
errno = 0;
value = strtoull(line, &end, base);
if (errno == ERANGE) {
return drgn_error_create(DRGN_ERROR_OVERFLOW,
"number in VMCOREINFO is too large");
} else if (errno || end == line || end != newline) {
return drgn_error_create(DRGN_ERROR_OVERFLOW,
"number in VMCOREINFO is invalid");
}
*ret = value;
return NULL;
}
struct drgn_error *parse_vmcoreinfo(const char *desc, size_t descsz,
struct vmcoreinfo *ret)
{
struct drgn_error *err;
const char *line = desc, *end = &desc[descsz];
ret->osrelease[0] = '\0';
ret->page_size = 0;
ret->kaslr_offset = 0;
helpers: add pgtable_l5_enabled()
2020-04-09 22:29:47 +01:00
ret->pgtable_l5_enabled = false;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
while (line < end) {
const char *newline;
newline = memchr(line, '\n', end - line);
if (!newline)
break;
if (linematch(&line, "OSRELEASE=")) {
if ((size_t)(newline - line) >=
sizeof(ret->osrelease)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"OSRELEASE in VMCOREINFO is too long");
}
memcpy(ret->osrelease, line, newline - line);
ret->osrelease[newline - line] = '\0';
} else if (linematch(&line, "PAGESIZE=")) {
err = line_to_u64(line, newline, 0, &ret->page_size);
if (err)
return err;
} else if (linematch(&line, "KERNELOFFSET=")) {
err = line_to_u64(line, newline, 16,
&ret->kaslr_offset);
if (err)
return err;
libdrgn: use swapper_pg_dir in vmcoreinfo for fallback PAGE_OFFSET I originally wanted to avoid depending on another vmcoreinfo field, but an the next change is going to depend on swapper_pg_dir in vmcoreinfo anyways, and it ends up being simpler to use it.
2020-05-01 09:00:27 +01:00
} else if (linematch(&line, "SYMBOL(swapper_pg_dir)=")) {
err = line_to_u64(line, newline, 16,
&ret->swapper_pg_dir);
if (err)
return err;
helpers: add pgtable_l5_enabled()
2020-04-09 22:29:47 +01:00
} else if (linematch(&line, "NUMBER(pgtable_l5_enabled)=")) {
uint64_t tmp;
err = line_to_u64(line, newline, 0, &tmp);
if (err)
return err;
ret->pgtable_l5_enabled = tmp;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
line = newline + 1;
}
if (!ret->osrelease[0]) {
return drgn_error_create(DRGN_ERROR_OTHER,
"VMCOREINFO does not contain valid OSRELEASE");
}
if (!ret->page_size) {
return drgn_error_create(DRGN_ERROR_OTHER,
"VMCOREINFO does not contain valid PAGESIZE");
}
libdrgn: use swapper_pg_dir in vmcoreinfo for fallback PAGE_OFFSET I originally wanted to avoid depending on another vmcoreinfo field, but an the next change is going to depend on swapper_pg_dir in vmcoreinfo anyways, and it ends up being simpler to use it.
2020-05-01 09:00:27 +01:00
if (!ret->swapper_pg_dir) {
return drgn_error_create(DRGN_ERROR_OTHER,
"VMCOREINFO does not contain valid swapper_pg_dir");
}
helpers: add pgtable_l5_enabled()
2020-04-09 22:29:47 +01:00
/* KERNELOFFSET and pgtable_l5_enabled are optional. */
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
return NULL;
}
libdrgn: add /proc/kcore physical segments on old kernels Before Linux v4.11, /proc/kcore didn't have valid physical addresses, so it's currently not possible to read from physical memory on old kernels. However, if we can figure out the address of the direct mapping, then we can determine the corresponding physical addresses for the segments and add them.
2020-05-04 08:44:44 +01:00
struct drgn_error *proc_kallsyms_symbol_addr(const char *name,
unsigned long *ret)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
struct drgn_error *err;
FILE *file;
char *line = NULL;
size_t n = 0;
file = fopen("/proc/kallsyms", "r");
if (!file)
libdrgn: reorder drgn_error_create_os() arguments To make it more consistent with the upcoming drgn_error_format_os().
2019-07-11 23:58:23 +01:00
return drgn_error_create_os("fopen", errno, "/proc/kallsyms");
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
for (;;) {
char *addr_str, *sym_str, *saveptr, *end;
errno = 0;
if (getline(&line, &n, file) == -1) {
if (errno) {
libdrgn: reorder drgn_error_create_os() arguments To make it more consistent with the upcoming drgn_error_format_os().
2019-07-11 23:58:23 +01:00
err = drgn_error_create_os("getline", errno,
"/proc/kallsyms");
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
} else {
libdrgn: add /proc/kcore physical segments on old kernels Before Linux v4.11, /proc/kcore didn't have valid physical addresses, so it's currently not possible to read from physical memory on old kernels. However, if we can figure out the address of the direct mapping, then we can determine the corresponding physical addresses for the segments and add them.
2020-05-04 08:44:44 +01:00
err = &drgn_not_found;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
break;
}
addr_str = strtok_r(line, "\t ", &saveptr);
if (!addr_str || !*addr_str)
goto invalid;
if (!strtok_r(NULL, "\t ", &saveptr))
goto invalid;
sym_str = strtok_r(NULL, "\t\n ", &saveptr);
if (!sym_str)
goto invalid;
if (strcmp(sym_str, name) != 0)
continue;
errno = 0;
*ret = strtoul(line, &end, 16);
if (errno || *end) {
invalid:
err = drgn_error_create(DRGN_ERROR_OTHER,
"could not parse /proc/kallsyms");
break;
}
err = NULL;
break;
}
free(line);
fclose(file);
return err;
}
/*
* Before Linux kernel commit 23c85094fe18 ("proc/kcore: add vmcoreinfo note to
libdrgn: add /proc/kcore physical segments on old kernels Before Linux v4.11, /proc/kcore didn't have valid physical addresses, so it's currently not possible to read from physical memory on old kernels. However, if we can figure out the address of the direct mapping, then we can determine the corresponding physical addresses for the segments and add them.
2020-05-04 08:44:44 +01:00
* /proc/kcore") (in v4.19), /proc/kcore didn't have a VMCOREINFO note. Instead,
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
* we can read from the physical address of the vmcoreinfo note exported in
libdrgn: add /proc/kcore physical segments on old kernels Before Linux v4.11, /proc/kcore didn't have valid physical addresses, so it's currently not possible to read from physical memory on old kernels. However, if we can figure out the address of the direct mapping, then we can determine the corresponding physical addresses for the segments and add them.
2020-05-04 08:44:44 +01:00
* sysfs.
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
*/
libdrgn: make addresses wrap around when reading memory Define that addresses for memory reads wrap around after the maximum address rather than the current unpredictable behavior. This is done by: 1. Reworking drgn_memory_reader to work with an inclusive address range so that a segment can contain UINT64_MAX. drgn_memory_reader remains agnostic to the maximum address and requires that address ranges do not overflow a uint64_t. 2. Adding the overflow/wrap-around logic to drgn_program_add_memory_segment() and drgn_program_read_memory(). 3. Changing direct uses of drgn_memory_reader_reader() to drgn_program_read_memory() now that they are no longer equivalent. (For some platforms, a fault might be more appropriate than wrapping around, but this is a step in the right direction.) Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-06-04 01:43:27 +01:00
struct drgn_error *read_vmcoreinfo_fallback(struct drgn_program *prog)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
struct drgn_error *err;
FILE *file;
libdrgn: read vmcoreinfo physical address as uint64_t Even on 32-bit architectures, physical addresses can be 64 bits (e.g., x86 with PAE). It's unlikely that the vmcoreinfo note would be in such an address, but let's always parse it as a uint64_t just to be safe.
2020-05-04 18:23:32 +01:00
uint64_t address;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
size_t size;
char *buf;
Elf64_Nhdr *nhdr;
file = fopen("/sys/kernel/vmcoreinfo", "r");
if (!file) {
libdrgn: reorder drgn_error_create_os() arguments To make it more consistent with the upcoming drgn_error_format_os().
2019-07-11 23:58:23 +01:00
return drgn_error_create_os("fopen", errno,
"/sys/kernel/vmcoreinfo");
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: read vmcoreinfo physical address as uint64_t Even on 32-bit architectures, physical addresses can be 64 bits (e.g., x86 with PAE). It's unlikely that the vmcoreinfo note would be in such an address, but let's always parse it as a uint64_t just to be safe.
2020-05-04 18:23:32 +01:00
if (fscanf(file, "%" SCNx64 "%zx", &address, &size) != 2) {
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
fclose(file);
return drgn_error_create(DRGN_ERROR_OTHER,
"could not parse /sys/kernel/vmcoreinfo");
}
fclose(file);
buf = malloc(size);
if (!buf)
return &drgn_enomem;
libdrgn: make addresses wrap around when reading memory Define that addresses for memory reads wrap around after the maximum address rather than the current unpredictable behavior. This is done by: 1. Reworking drgn_memory_reader to work with an inclusive address range so that a segment can contain UINT64_MAX. drgn_memory_reader remains agnostic to the maximum address and requires that address ranges do not overflow a uint64_t. 2. Adding the overflow/wrap-around logic to drgn_program_add_memory_segment() and drgn_program_read_memory(). 3. Changing direct uses of drgn_memory_reader_reader() to drgn_program_read_memory() now that they are no longer equivalent. (For some platforms, a fault might be more appropriate than wrapping around, but this is a step in the right direction.) Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-06-04 01:43:27 +01:00
err = drgn_program_read_memory(prog, buf, address, size, true);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
goto out;
/*
* The first 12 bytes are the Elf{32,64}_Nhdr (it's the same in both
* formats). The name is padded up to 4 bytes, so the descriptor starts
* at byte 24.
*/
nhdr = (Elf64_Nhdr *)buf;
if (size < 24 || nhdr->n_namesz != 11 ||
memcmp(buf + sizeof(*nhdr), "VMCOREINFO", 10) != 0 ||
nhdr->n_descsz > size - 24) {
err = drgn_error_create(DRGN_ERROR_OTHER,
"VMCOREINFO is invalid");
goto out;
}
libdrgn: make addresses wrap around when reading memory Define that addresses for memory reads wrap around after the maximum address rather than the current unpredictable behavior. This is done by: 1. Reworking drgn_memory_reader to work with an inclusive address range so that a segment can contain UINT64_MAX. drgn_memory_reader remains agnostic to the maximum address and requires that address ranges do not overflow a uint64_t. 2. Adding the overflow/wrap-around logic to drgn_program_add_memory_segment() and drgn_program_read_memory(). 3. Changing direct uses of drgn_memory_reader_reader() to drgn_program_read_memory() now that they are no longer equivalent. (For some platforms, a fault might be more appropriate than wrapping around, but this is a step in the right direction.) Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-06-04 01:43:27 +01:00
err = parse_vmcoreinfo(buf + 24, nhdr->n_descsz, &prog->vmcoreinfo);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
out:
free(buf);
return err;
}
libdrgn: fix _page_offset() helper and move to object finder The internal _page_offset() helper gets the value of PAGE_OFFSET, but the fallback when KASLR is disabled has been out of date since Linux v4.20 and never handled 5-level page tables. Additionally, it makes more sense as part of the Linux kernel (formerly vmcoreinfo) object finder so that it's cleanly accessible outside of drgn internals.
2020-04-09 22:59:42 +01:00
struct drgn_error *linux_kernel_object_find(const char *name, size_t name_len,
const char *filename,
enum drgn_find_object_flags flags,
void *arg, struct drgn_object *ret)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
{
struct drgn_error *err;
struct drgn_program *prog = arg;
libdrgn: replace symbol index with object index struct drgn_symbol doesn't really represent a symbol; it's just an object which hasn't been fully initialized (see c2be52dff05d ("libdrgn: rename object index to symbol index"), it used to be called a "partial object"). For stack traces, we're going to have a notion of a symbol that more closely represents an ELF symbol, so let's get rid of the temporary struct drgn_symbol representation and just return an object directly.
2019-07-24 00:26:29 +01:00
if (!filename && (flags & DRGN_FIND_OBJECT_CONSTANT)) {
struct drgn_qualified_type qualified_type = {};
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
libdrgn: fix _page_offset() helper and move to object finder The internal _page_offset() helper gets the value of PAGE_OFFSET, but the fallback when KASLR is disabled has been out of date since Linux v4.20 and never handled 5-level page tables. Additionally, it makes more sense as part of the Linux kernel (formerly vmcoreinfo) object finder so that it's cleanly accessible outside of drgn internals.
2020-04-09 22:59:42 +01:00
if (name_len == strlen("PAGE_OFFSET") &&
memcmp(name, "PAGE_OFFSET", name_len) == 0) {
libdrgn: rename "unavailable" objects to "absent" objects I was going to add an Object.available_ attribute, but that made me realize that the naming is somewhat ambiguous, as a reference object with an invalid address might also be considered "unavailable" by users. Use the name "absent" instead, which is more clear: the object isn't there at all. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-29 22:41:01 +00:00
if (prog->page_offset.kind == DRGN_OBJECT_ABSENT) {
libdrgn: fix _page_offset() helper and move to object finder The internal _page_offset() helper gets the value of PAGE_OFFSET, but the fallback when KASLR is disabled has been out of date since Linux v4.20 and never handled 5-level page tables. Additionally, it makes more sense as part of the Linux kernel (formerly vmcoreinfo) object finder so that it's cleanly accessible outside of drgn internals.
2020-04-09 22:59:42 +01:00
if (!prog->has_platform ||
!prog->platform.arch->linux_kernel_get_page_offset)
return &drgn_not_found;
libdrgn: cache page_offset and vmemmap as objects instead of uint64_t This is a little cleaner and saves on conversions back and forth between C values and objects. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-10 10:40:07 +00:00
err = prog->platform.arch->linux_kernel_get_page_offset(&prog->page_offset);
if (err)
libdrgn: fix _page_offset() helper and move to object finder The internal _page_offset() helper gets the value of PAGE_OFFSET, but the fallback when KASLR is disabled has been out of date since Linux v4.20 and never handled 5-level page tables. Additionally, it makes more sense as part of the Linux kernel (formerly vmcoreinfo) object finder so that it's cleanly accessible outside of drgn internals.
2020-04-09 22:59:42 +01:00
return err;
}
libdrgn: cache page_offset and vmemmap as objects instead of uint64_t This is a little cleaner and saves on conversions back and forth between C values and objects. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-10 10:40:07 +00:00
return drgn_object_copy(ret, &prog->page_offset);
libdrgn: fix _page_offset() helper and move to object finder The internal _page_offset() helper gets the value of PAGE_OFFSET, but the fallback when KASLR is disabled has been out of date since Linux v4.20 and never handled 5-level page tables. Additionally, it makes more sense as part of the Linux kernel (formerly vmcoreinfo) object finder so that it's cleanly accessible outside of drgn internals.
2020-04-09 22:59:42 +01:00
} else if (name_len == strlen("PAGE_SHIFT") &&
memcmp(name, "PAGE_SHIFT", name_len) == 0) {
libdrgn: fold drgn_type_index into drgn_program This is preparation for associating types with a program. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-04-23 00:23:26 +01:00
err = drgn_program_find_primitive_type(prog,
DRGN_C_TYPE_INT,
&qualified_type.type);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (err)
return err;
libdrgn: replace symbol index with object index struct drgn_symbol doesn't really represent a symbol; it's just an object which hasn't been fully initialized (see c2be52dff05d ("libdrgn: rename object index to symbol index"), it used to be called a "partial object"). For stack traces, we're going to have a notion of a symbol that more closely represents an ELF symbol, so let's get rid of the temporary struct drgn_symbol representation and just return an object directly.
2019-07-24 00:26:29 +01:00
return drgn_object_set_signed(ret, qualified_type,
ctz(prog->vmcoreinfo.page_size),
0);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
} else if (name_len == strlen("PAGE_SIZE") &&
memcmp(name, "PAGE_SIZE", name_len) == 0) {
libdrgn: fold drgn_type_index into drgn_program This is preparation for associating types with a program. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-04-23 00:23:26 +01:00
err = drgn_program_find_primitive_type(prog,
DRGN_C_TYPE_UNSIGNED_LONG,
&qualified_type.type);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (err)
return err;
libdrgn: replace symbol index with object index struct drgn_symbol doesn't really represent a symbol; it's just an object which hasn't been fully initialized (see c2be52dff05d ("libdrgn: rename object index to symbol index"), it used to be called a "partial object"). For stack traces, we're going to have a notion of a symbol that more closely represents an ELF symbol, so let's get rid of the temporary struct drgn_symbol representation and just return an object directly.
2019-07-24 00:26:29 +01:00
return drgn_object_set_unsigned(ret, qualified_type,
prog->vmcoreinfo.page_size,
0);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
} else if (name_len == strlen("PAGE_MASK") &&
memcmp(name, "PAGE_MASK", name_len) == 0) {
libdrgn: fold drgn_type_index into drgn_program This is preparation for associating types with a program. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-04-23 00:23:26 +01:00
err = drgn_program_find_primitive_type(prog,
DRGN_C_TYPE_UNSIGNED_LONG,
&qualified_type.type);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (err)
return err;
libdrgn: replace symbol index with object index struct drgn_symbol doesn't really represent a symbol; it's just an object which hasn't been fully initialized (see c2be52dff05d ("libdrgn: rename object index to symbol index"), it used to be called a "partial object"). For stack traces, we're going to have a notion of a symbol that more closely represents an ELF symbol, so let's get rid of the temporary struct drgn_symbol representation and just return an object directly.
2019-07-24 00:26:29 +01:00
return drgn_object_set_unsigned(ret, qualified_type,
~(prog->vmcoreinfo.page_size - 1),
0);
libdrgn: add UTS_RELEASE to vmcoreinfo_object_find The osrelease is accessible via init_uts_ns.name.release, but we can also get it straight out of vmcoreinfo, which will be useful for the next change. UTS_RELEASE is the name of the macro defined in the kernel.
2020-02-19 19:35:52 +00:00
} else if (name_len == strlen("UTS_RELEASE") &&
memcmp(name, "UTS_RELEASE", name_len) == 0) {
size_t len;
libdrgn: fold drgn_type_index into drgn_program This is preparation for associating types with a program. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-04-23 00:23:26 +01:00
err = drgn_program_find_primitive_type(prog,
DRGN_C_TYPE_CHAR,
&qualified_type.type);
libdrgn: add UTS_RELEASE to vmcoreinfo_object_find The osrelease is accessible via init_uts_ns.name.release, but we can also get it straight out of vmcoreinfo, which will be useful for the next change. UTS_RELEASE is the name of the macro defined in the kernel.
2020-02-19 19:35:52 +00:00
if (err)
return err;
qualified_type.qualifiers = DRGN_QUALIFIER_CONST;
len = strlen(prog->vmcoreinfo.osrelease);
Associate types with program I originally envisioned types as dumb descriptors. This mostly works for C because in C, types are fairly simple. However, even then the drgn_program_member_info() API is awkward. You should be able to look up a member directly from a type, but we need the program for caching purposes. This has also held me back from adding offsetof() or has_member() APIs. Things get even messier with C++. C++ template parameters can be objects (e.g., template <int N>). Such parameters would best be represented by a drgn object, which we need a drgn program for. Static members are a similar case. So, let's reimagine types as being owned by a program. This has a few parts: 1. In libdrgn, simple types are now created by factory functions, drgn_foo_type_create(). 2. To handle their variable length fields, compound types, enum types, and function types are constructed with a "builder" API. 3. Simple types are deduplicated. 4. The Python type factory functions are replaced by methods of the Program class. 5. While we're changing the API, the parameters to pointer_type() and array_type() are reordered to be more logical (and to allow pointer_type() to take a default size of None for the program's default pointer size). 6. Likewise, the type factory methods take qualifiers as a keyword argument only. A big part of this change is updating the tests and splitting up large test cases into smaller ones in a few places. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-07-16 00:34:56 +01:00
err = drgn_array_type_create(prog, qualified_type,
len + 1, &drgn_language_c,
&qualified_type.type);
libdrgn: add UTS_RELEASE to vmcoreinfo_object_find The osrelease is accessible via init_uts_ns.name.release, but we can also get it straight out of vmcoreinfo, which will be useful for the next change. UTS_RELEASE is the name of the macro defined in the kernel.
2020-02-19 19:35:52 +00:00
if (err)
return err;
qualified_type.qualifiers = 0;
Remove bit_offset from value objects There are a couple of reasons that it was the wrong choice to have a bit_offset for value objects: 1. When we store a buffer with a bit_offset, we're storing useless padding bits. 2. bit_offset describes a location, or in other words, part of an address. This makes sense for references, but not for values, which are just a bag of bytes. Get rid of union drgn_value.bit_offset in libdrgn, make Object.bit_offset None for value objects, and disallow passing bit_offset to the Object() constructor when creating a value. bit_offset can still be passed when creating an object from a buffer, but we'll shift the bytes down as necessary to store the value with no offset. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-11 19:18:54 +00:00
return drgn_object_set_from_buffer(ret, qualified_type,
prog->vmcoreinfo.osrelease,
Track byte order in scalar types instead of objects Currently, reference objects and buffer value objects have a byte order. However, this doesn't always make sense for a couple of reasons: - Byte order is only meaningful for scalars. What does it mean for a struct to be big endian? A struct doesn't have a most or least significant byte; its scalar members do. - The DWARF specification allows either types or variables to have a byte order (DW_AT_endianity). The only producer I could find that uses this is GCC for the scalar_storage_order type attribute, and it only uses it for base types, not variables. GDB only seems to use to check it for base types, as well. So, remove the byte order from objects, and move it to integer, boolean, floating-point, and pointer types. This model makes more sense, and it means that we can get the binary representation of any object now. The only downside is that we can no longer support a bit offset for non-scalars, but as far as I can tell, nothing needs that. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-02-18 00:13:23 +00:00
len + 1, 0, 0);
libdrgn: move _vmemmap() to object finder Similarly to PAGE_OFFSET, vmemmap makes more sense as part of the Linux kernel object finder than an internal helper. While we're here, let's fix the definition for 5-level page tables. This only matters for kernels with commit 77ef56e4f0fb ("x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y") but without eedb92abb9bb ("x86/mm: Make virtual memory layout dynamic for CONFIG_X86_5LEVEL=y") (namely, v4.14, v4.15, and v4.16); since v4.17, 5-level page table support enables KASLR.
2020-04-09 23:37:46 +01:00
} else if (name_len == strlen("vmemmap") &&
memcmp(name, "vmemmap", name_len) == 0) {
libdrgn: rename "unavailable" objects to "absent" objects I was going to add an Object.available_ attribute, but that made me realize that the naming is somewhat ambiguous, as a reference object with an invalid address might also be considered "unavailable" by users. Use the name "absent" instead, which is more clear: the object isn't there at all. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-29 22:41:01 +00:00
if (prog->vmemmap.kind == DRGN_OBJECT_ABSENT) {
libdrgn: move _vmemmap() to object finder Similarly to PAGE_OFFSET, vmemmap makes more sense as part of the Linux kernel object finder than an internal helper. While we're here, let's fix the definition for 5-level page tables. This only matters for kernels with commit 77ef56e4f0fb ("x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y") but without eedb92abb9bb ("x86/mm: Make virtual memory layout dynamic for CONFIG_X86_5LEVEL=y") (namely, v4.14, v4.15, and v4.16); since v4.17, 5-level page table support enables KASLR.
2020-04-09 23:37:46 +01:00
if (!prog->has_platform ||
!prog->platform.arch->linux_kernel_get_vmemmap)
return &drgn_not_found;
libdrgn: cache page_offset and vmemmap as objects instead of uint64_t This is a little cleaner and saves on conversions back and forth between C values and objects. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-10 10:40:07 +00:00
err = prog->platform.arch->linux_kernel_get_vmemmap(&prog->vmemmap);
if (err)
libdrgn: move _vmemmap() to object finder Similarly to PAGE_OFFSET, vmemmap makes more sense as part of the Linux kernel object finder than an internal helper. While we're here, let's fix the definition for 5-level page tables. This only matters for kernels with commit 77ef56e4f0fb ("x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y") but without eedb92abb9bb ("x86/mm: Make virtual memory layout dynamic for CONFIG_X86_5LEVEL=y") (namely, v4.14, v4.15, and v4.16); since v4.17, 5-level page table support enables KASLR.
2020-04-09 23:37:46 +01:00
return err;
}
libdrgn: cache page_offset and vmemmap as objects instead of uint64_t This is a little cleaner and saves on conversions back and forth between C values and objects. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-10 10:40:07 +00:00
return drgn_object_copy(ret, &prog->vmemmap);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
}
libdrgn: replace symbol index with object index struct drgn_symbol doesn't really represent a symbol; it's just an object which hasn't been fully initialized (see c2be52dff05d ("libdrgn: rename object index to symbol index"), it used to be called a "partial object"). For stack traces, we're going to have a notion of a symbol that more closely represents an ELF symbol, so let's get rid of the temporary struct drgn_symbol representation and just return an object directly.
2019-07-24 00:26:29 +01:00
return &drgn_not_found;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
struct kernel_module_iterator {
char *name;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
/* /proc/modules file or NULL. */
FILE *modules_file;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
union {
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
/* If using /proc/modules. */
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
struct {
size_t name_capacity;
uint64_t start, end;
};
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
/* If not using /proc/modules. */
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
struct {
struct drgn_qualified_type module_type;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
struct drgn_object mod, node, tmp1, tmp2, tmp3;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
uint64_t head;
};
};
};
static void kernel_module_iterator_deinit(struct kernel_module_iterator *it)
{
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
if (it->modules_file) {
fclose(it->modules_file);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
} else {
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
drgn_object_deinit(&it->tmp3);
drgn_object_deinit(&it->tmp2);
drgn_object_deinit(&it->tmp1);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
drgn_object_deinit(&it->node);
drgn_object_deinit(&it->mod);
}
free(it->name);
}
static struct drgn_error *
kernel_module_iterator_init(struct kernel_module_iterator *it,
libdrgn: add an environment variable to disable use of /proc/modules and /sys/module We use /proc/modules and /sys/module to find loaded kernel modules for the running kernel instead of walking the module list in the core dump as an optimization. To make it easier to test the core dump path, add an environment variable to disable the optimization. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 19:24:39 +01:00
struct drgn_program *prog, bool use_proc_and_sys)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
struct drgn_error *err;
it->name = NULL;
libdrgn: add an environment variable to disable use of /proc/modules and /sys/module We use /proc/modules and /sys/module to find loaded kernel modules for the running kernel instead of walking the module list in the core dump as an optimization. To make it easier to test the core dump path, add an environment variable to disable the optimization. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 19:24:39 +01:00
if (use_proc_and_sys) {
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
it->modules_file = fopen("/proc/modules", "r");
if (!it->modules_file) {
libdrgn: reorder drgn_error_create_os() arguments To make it more consistent with the upcoming drgn_error_format_os().
2019-07-11 23:58:23 +01:00
return drgn_error_create_os("fopen", errno,
"/proc/modules");
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
it->name_capacity = 0;
} else {
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
it->modules_file = NULL;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
err = drgn_program_find_type(prog, "struct module", NULL,
&it->module_type);
if (err)
return err;
drgn_object_init(&it->mod, prog);
drgn_object_init(&it->node, prog);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
drgn_object_init(&it->tmp1, prog);
drgn_object_init(&it->tmp2, prog);
drgn_object_init(&it->tmp3, prog);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
err = drgn_program_find_object(prog, "modules", NULL,
DRGN_FIND_OBJECT_VARIABLE,
&it->node);
if (err)
goto err;
err = drgn_object_address_of(&it->node, &it->node);
if (err)
goto err;
err = drgn_object_read(&it->node, &it->node);
if (err)
goto err;
err = drgn_object_read_unsigned(&it->node, &it->head);
if (err)
goto err;
}
return NULL;
err:
kernel_module_iterator_deinit(it);
return err;
}
static struct drgn_error *
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
kernel_module_iterator_next_live(struct kernel_module_iterator *it)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
errno = 0;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
ssize_t ret = getline(&it->name, &it->name_capacity, it->modules_file);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (ret == -1) {
if (errno) {
libdrgn: reorder drgn_error_create_os() arguments To make it more consistent with the upcoming drgn_error_format_os().
2019-07-11 23:58:23 +01:00
return drgn_error_create_os("getline", errno,
"/proc/modules");
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
} else {
return &drgn_stop;
}
}
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
char *p = strchr(it->name, ' ');
size_t size;
if (!p ||
sscanf(p + 1, "%zu %*s %*s %*s %" SCNx64, &size, &it->start) != 2) {
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
return drgn_error_create(DRGN_ERROR_OTHER,
"could not parse /proc/modules");
}
*p = '\0';
it->end = it->start + size;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
return NULL;
}
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
/**
* Get the the next loaded kernel module.
*
* After this is called, @c it->name is set to the name of the kernel module,
* and @c it->start and @c it->end are set to the address range of the kernel
* module. These are valid until the next time this is called or the iterator is
* destroyed.
*
* @return @c NULL on success, non-@c NULL on error. In particular, when there
libdrgn: clean up usage of drgn_stop Use drgn_not_found where it's more appropriate, and check explicitly against drgn_stop instead of err->code == DRGN_ERROR_STOP. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-03-05 20:46:06 +00:00
* are no more modules, returns &@ref drgn_stop.
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
*/
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
static struct drgn_error *
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
kernel_module_iterator_next(struct kernel_module_iterator *it)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
if (it->modules_file)
return kernel_module_iterator_next_live(it);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
struct drgn_error *err;
err = drgn_object_member_dereference(&it->node, &it->node, "next");
if (err)
return err;
err = drgn_object_read(&it->node, &it->node);
if (err)
return err;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
uint64_t addr;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
err = drgn_object_read_unsigned(&it->node, &addr);
if (err)
return err;
if (addr == it->head)
return &drgn_stop;
err = drgn_object_container_of(&it->mod, &it->node, it->module_type,
"list");
if (err)
return err;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
err = drgn_object_member_dereference(&it->tmp1, &it->mod, "name");
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
return err;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
char *name;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
err = drgn_object_read_c_string(&it->tmp1, &name);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
return err;
free(it->name);
it->name = name;
return NULL;
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
struct kernel_module_section_iterator {
struct kernel_module_iterator *kmod_it;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
/* /sys/module/$module/sections directory or NULL. */
DIR *sections_dir;
/* If not using /sys/module/$module/sections. */
uint64_t i;
uint64_t nsections;
char *name;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
};
static struct drgn_error *
kernel_module_section_iterator_init(struct kernel_module_section_iterator *it,
struct kernel_module_iterator *kmod_it)
{
struct drgn_error *err;
it->kmod_it = kmod_it;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
if (kmod_it->modules_file) {
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
char *path;
if (asprintf(&path, "/sys/module/%s/sections",
kmod_it->name) == -1)
return &drgn_enomem;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
it->sections_dir = opendir(path);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
free(path);
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
if (!it->sections_dir) {
return drgn_error_format_os("opendir", errno,
"/sys/module/%s/sections",
kmod_it->name);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
return NULL;
} else {
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
it->sections_dir = NULL;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
it->i = 0;
it->name = NULL;
/* it->nsections = mod->sect_attrs->nsections */
err = drgn_object_member_dereference(&kmod_it->tmp1,
&kmod_it->mod,
"sect_attrs");
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
return err;
err = drgn_object_member_dereference(&kmod_it->tmp2,
&kmod_it->tmp1,
"nsections");
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
return err;
err = drgn_object_read_unsigned(&kmod_it->tmp2,
&it->nsections);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
return err;
/* kmod_it->tmp1 = mod->sect_attrs->attrs */
return drgn_object_member_dereference(&kmod_it->tmp1,
&kmod_it->tmp1, "attrs");
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
static void
kernel_module_section_iterator_deinit(struct kernel_module_section_iterator *it)
{
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
if (it->sections_dir)
closedir(it->sections_dir);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
else
free(it->name);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
static struct drgn_error *
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
kernel_module_section_iterator_next_live(struct kernel_module_section_iterator *it,
const char **name_ret,
uint64_t *address_ret)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
struct dirent *ent;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
while ((errno = 0, ent = readdir(it->sections_dir))) {
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (ent->d_type == DT_DIR)
continue;
if (ent->d_type == DT_UNKNOWN) {
struct stat st;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
if (fstatat(dirfd(it->sections_dir), ent->d_name, &st,
0) == -1) {
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
return drgn_error_format_os("fstatat", errno,
"/sys/module/%s/sections/%s",
it->kmod_it->name,
ent->d_name);
}
if (S_ISDIR(st.st_mode))
continue;
}
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
int fd = openat(dirfd(it->sections_dir), ent->d_name, O_RDONLY);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (fd == -1) {
return drgn_error_format_os("openat", errno,
"/sys/module/%s/sections/%s",
it->kmod_it->name,
ent->d_name);
}
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
FILE *file = fdopen(fd, "r");
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (!file) {
close(fd);
return drgn_error_create_os("fdopen", errno, NULL);
}
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
int ret = fscanf(file, "%" SCNx64, address_ret);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
fclose(file);
if (ret != 1) {
return drgn_error_format(DRGN_ERROR_OTHER,
"could not parse /sys/module/%s/sections/%s",
it->kmod_it->name,
ent->d_name);
}
*name_ret = ent->d_name;
return NULL;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (errno) {
return drgn_error_format_os("readdir", errno,
"/sys/module/%s/sections",
it->kmod_it->name);
} else {
return &drgn_stop;
}
}
static struct drgn_error *
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
kernel_module_section_iterator_next(struct kernel_module_section_iterator *it,
const char **name_ret,
uint64_t *address_ret)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
{
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
if (it->sections_dir) {
return kernel_module_section_iterator_next_live(it, name_ret,
address_ret);
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
struct drgn_error *err;
struct kernel_module_iterator *kmod_it = it->kmod_it;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (it->i >= it->nsections)
return &drgn_stop;
err = drgn_object_subscript(&kmod_it->tmp2, &kmod_it->tmp1, it->i++);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
return err;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
err = drgn_object_member(&kmod_it->tmp3, &kmod_it->tmp2, "address");
if (err)
return err;
err = drgn_object_read_unsigned(&kmod_it->tmp3, address_ret);
if (err)
return err;
libdrgn: update module section iterator for Linux v5.8 Linux v5.8 changed the module section structure, so we need to get the section name differently. Closes #73. Reported-by: Serapheim Dimitropoulos <serapheim@delphix.com> Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 20:41:24 +01:00
/*
* Since Linux kernel commit ed66f991bb19 ("module: Refactor section
* attr into bin attribute") (in v5.8), the section name is
* module_sect_attr.battr.attr.name. Before that, it is simply
* module_sect_attr.name.
*/
err = drgn_object_member(&kmod_it->tmp2, &kmod_it->tmp2, "battr");
if (!err) {
err = drgn_object_member(&kmod_it->tmp2, &kmod_it->tmp2,
"attr");
if (err)
return err;
} else {
if (err->code != DRGN_ERROR_LOOKUP)
return err;
drgn_error_destroy(err);
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
err = drgn_object_member(&kmod_it->tmp3, &kmod_it->tmp2, "name");
if (err)
return err;
libdrgn: refactor kernel module iterator The next commit will allow using the offline path for the live kernel, so the offline naming won't make much sense. Fold the offline path into the top-level functions, and make the live path an escape hatch. Also add some comments and improve naming for the file and directory handles and update the coding style. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 07:22:01 +01:00
char *name;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
err = drgn_object_read_c_string(&kmod_it->tmp3, &name);
if (err)
return err;
free(it->name);
*name_ret = it->name = name;
return NULL;
}
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
/*
* /lib/modules/$(uname -r)/modules.dep.bin maps all installed kernel modules to
* their filesystem path (and dependencies, which we don't care about). It is
* generated by depmod; the format is a fairly simple serialized radix tree.
*
* modules.dep(5) contains a warning: "These files are not intended for editing
* or use by any additional utilities as their format is subject to change in
* the future." But, the format hasn't changed since 2009, and pulling in
* libkmod is overkill since we only need a very small subset of its
* functionality (plus our minimal parser is more efficient). If the format
* changes in the future, we can reevaluate this.
*/
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
struct depmod_index {
void *addr;
size_t len;
char path[256];
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
};
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
static void depmod_index_deinit(struct depmod_index *depmod)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
munmap(depmod->addr, depmod->len);
}
struct depmod_index_buffer {
struct binary_buffer bb;
struct depmod_index *depmod;
};
static struct drgn_error *depmod_index_buffer_error(struct binary_buffer *bb,
const char *pos,
const char *message)
{
struct depmod_index_buffer *buffer =
container_of(bb, struct depmod_index_buffer, bb);
return drgn_error_format(DRGN_ERROR_OTHER, "%s: %#tx: %s",
buffer->depmod->path,
pos - (const char *)buffer->depmod->addr,
message);
}
static void depmod_index_buffer_init(struct depmod_index_buffer *buffer,
struct depmod_index *depmod)
{
binary_buffer_init(&buffer->bb, depmod->addr, depmod->len, false,
depmod_index_buffer_error);
buffer->depmod = depmod;
}
static struct drgn_error *depmod_index_validate(struct depmod_index *depmod)
{
struct drgn_error *err;
struct depmod_index_buffer buffer;
depmod_index_buffer_init(&buffer, depmod);
uint32_t magic;
if ((err = binary_buffer_next_u32(&buffer.bb, &magic)))
return err;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (magic != 0xb007f457) {
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
return binary_buffer_error(&buffer.bb,
"invalid magic 0x%" PRIx32, magic);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
uint32_t version;
if ((err = binary_buffer_next_u32(&buffer.bb, &version)))
return err;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (version != 0x00020001) {
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
return binary_buffer_error(&buffer.bb,
"unknown version 0x%" PRIx32,
version);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
return NULL;
}
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
static struct drgn_error *depmod_index_init(struct depmod_index *depmod,
const char *osrelease)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
struct drgn_error *err;
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
snprintf(depmod->path, sizeof(depmod->path),
"/lib/modules/%s/modules.dep.bin", osrelease);
int fd = open(depmod->path, O_RDONLY);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (fd == -1)
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
return drgn_error_create_os("open", errno, depmod->path);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
struct stat st;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (fstat(fd, &st) == -1) {
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
err = drgn_error_create_os("fstat", errno, depmod->path);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
goto out;
}
if (st.st_size < 0 || st.st_size > SIZE_MAX) {
err = &drgn_enomem;
goto out;
}
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
void *addr = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (addr == MAP_FAILED) {
err = drgn_error_create_os("mmap", errno, depmod->path);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
goto out;
}
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
depmod->addr = addr;
depmod->len = st.st_size;
err = depmod_index_validate(depmod);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
depmod_index_deinit(depmod);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
out:
close(fd);
return err;
}
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
/*
* Look up the path of the kernel module with the given name.
*
* @param[in] name Name of the kernel module.
* @param[out] path_ret Returned path of the kernel module, relative to
* /lib/modules/$(uname -r). This is @em not null-terminated. @c NULL if not
* found.
* @param[out] len_ret Returned length of @p path_ret.
*/
static struct drgn_error *depmod_index_find(struct depmod_index *depmod,
const char *name,
const char **path_ret,
size_t *len_ret)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
libdrgn: linux_kernel: use names for kmod index constants This makes it much easier to follow along with the code and understand the format.
2020-06-25 21:53:46 +01:00
static const uint32_t INDEX_NODE_MASK = UINT32_C(0x0fffffff);
static const uint32_t INDEX_NODE_CHILDS = UINT32_C(0x20000000);
static const uint32_t INDEX_NODE_VALUES = UINT32_C(0x40000000);
static const uint32_t INDEX_NODE_PREFIX = UINT32_C(0x80000000);
libdrgn: clean up read.h helpers and avoid undefined pointer behavior There are a couple of related ways that we can cause undefined behavior when parsing a malformed DWARF or depmod index file: 1. There are several places where we increment the cursor to skip past some data. It is undefined behavior if the result points out of bounds of the data, even if we don't attempt to dereference it. 2. read_in_bounds() checks that ptr <= end. This pointer comparison is only defined if ptr and end both point to elements of the same array object or one past the last element. If ptr has gone past end, then this comparison is likely undefined anyways. Fix it by adding a helper to skip past data with bounds checking. Then, all of the helpers can assume that ptr <= end and maintain that invariant. while we're here and auditing all of the call sites, let's clean up the API and rename it from read_foo() to the less generic mread_foo(). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-07-07 01:44:39 +01:00
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
struct drgn_error *err;
struct depmod_index_buffer buffer;
depmod_index_buffer_init(&buffer, depmod);
/* depmod_index_validate() already checked that this is within bounds. */
buffer.bb.pos += 8;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
uint32_t offset;
for (;;) {
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
if ((err = binary_buffer_next_u32(&buffer.bb, &offset)))
return err;
if ((offset & INDEX_NODE_MASK) > depmod->len) {
return binary_buffer_error(&buffer.bb,
"offset is out of bounds");
}
buffer.bb.pos = (const char *)depmod->addr + (offset & INDEX_NODE_MASK);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: linux_kernel: use names for kmod index constants This makes it much easier to follow along with the code and understand the format.
2020-06-25 21:53:46 +01:00
if (offset & INDEX_NODE_PREFIX) {
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
const char *prefix;
size_t prefix_len;
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
if ((err = binary_buffer_next_string(&buffer.bb,
&prefix,
&prefix_len)))
return err;
if (strncmp(name, prefix, prefix_len) != 0)
goto not_found;
name += prefix_len;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: linux_kernel: use names for kmod index constants This makes it much easier to follow along with the code and understand the format.
2020-06-25 21:53:46 +01:00
if (offset & INDEX_NODE_CHILDS) {
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
uint8_t first, last;
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
if ((err = binary_buffer_next_u8(&buffer.bb, &first)) ||
(err = binary_buffer_next_u8(&buffer.bb, &last)))
return err;
if (*name) {
uint8_t cur = *name;
if (cur < first || cur > last)
goto not_found;
if ((err = binary_buffer_skip(&buffer.bb,
4 * (cur - first))))
return err;
name++;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
continue;
} else {
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
if ((err = binary_buffer_skip(&buffer.bb,
4 * (last - first + 1))))
return err;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
break;
}
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
} else if (*name) {
goto not_found;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
} else {
break;
}
}
libdrgn: linux_kernel: use names for kmod index constants This makes it much easier to follow along with the code and understand the format.
2020-06-25 21:53:46 +01:00
if (!(offset & INDEX_NODE_VALUES))
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
goto not_found;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: clean up read.h helpers and avoid undefined pointer behavior There are a couple of related ways that we can cause undefined behavior when parsing a malformed DWARF or depmod index file: 1. There are several places where we increment the cursor to skip past some data. It is undefined behavior if the result points out of bounds of the data, even if we don't attempt to dereference it. 2. read_in_bounds() checks that ptr <= end. This pointer comparison is only defined if ptr and end both point to elements of the same array object or one past the last element. If ptr has gone past end, then this comparison is likely undefined anyways. Fix it by adding a helper to skip past data with bounds checking. Then, all of the helpers can assume that ptr <= end and maintain that invariant. while we're here and auditing all of the call sites, let's clean up the API and rename it from read_foo() to the less generic mread_foo(). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-07-07 01:44:39 +01:00
uint32_t value_count;
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
if ((err = binary_buffer_next_u32(&buffer.bb, &value_count)))
return err;
if (!value_count)
goto not_found; /* Or is this malformed? */
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
/* Skip over priority. */
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
if ((err = binary_buffer_skip(&buffer.bb, 4)))
return err;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
const char *colon = memchr(buffer.bb.pos, ':',
buffer.bb.end - buffer.bb.pos);
if (!colon) {
return binary_buffer_error(&buffer.bb,
"expected string containing ':'");
}
*path_ret = buffer.bb.pos;
*len_ret = colon - buffer.bb.pos;
return NULL;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
not_found:
*path_ret = NULL;
return NULL;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
/*
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
* Identify an ELF file as a kernel module, vmlinux, or neither. A kernel module
* should have sections named .gnu.linkonce.this_module and .modinfo; we return
* those sections and classify the file as a kernel module if either is present.
*
* If neither is present, and the file has a section named .init.text, we
* classify it as vmlinux.
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
*/
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
static struct drgn_error *identify_kernel_elf(Elf *elf,
Elf_Scn **this_module_scn_ret,
Elf_Scn **modinfo_scn_ret,
bool *is_vmlinux_ret)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
size_t shstrndx;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
Elf_Scn *scn;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
bool have_init_text = false;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (elf_getshdrstrndx(elf, &shstrndx))
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
return drgn_error_libelf();
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
scn = *this_module_scn_ret = *modinfo_scn_ret = NULL;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
while ((scn = elf_nextscn(elf, scn))) {
GElf_Shdr *shdr, shdr_mem;
const char *scnname;
shdr = gelf_getshdr(scn, &shdr_mem);
if (!shdr)
continue;
scnname = elf_strptr(elf, shstrndx, shdr->sh_name);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (!scnname)
libdrgn: handle errors from elf_strptr() For some reason, we consistently ignore errors from elf_strptr(), but we shouldn't. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-03-26 21:28:16 +00:00
return drgn_error_libelf();
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (strcmp(scnname, ".gnu.linkonce.this_module") == 0)
*this_module_scn_ret = scn;
else if (strcmp(scnname, ".modinfo") == 0)
*modinfo_scn_ret = scn;
else if (strcmp(scnname, ".init.text") == 0)
have_init_text = true;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
*is_vmlinux_ret = (!*this_module_scn_ret && !*modinfo_scn_ret &&
have_init_text);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
return NULL;
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
/*
* Since Linux kernel commit 3e2e857f9c3a ("module: Add module name to modinfo")
* (in v4.13), we can get the module name from .modinfo.
*/
static struct drgn_error *
get_kernel_module_name_from_modinfo(Elf_Scn *modinfo_scn, const char **ret)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
{
struct drgn_error *err;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
Elf_Data *data;
const char *p, *end, *nul;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (modinfo_scn) {
err = read_elf_section(modinfo_scn, &data);
libdrgn: split up drgn_program_get_dwarf() We don't need to get the DWARF index at the time we get the Dwfl handle, so get rid of drgn_program_get_dwarf(), add drgn_program_get_dwfl(), and create the DWARF index right before we update in a new function, drgn_program_update_dwarf_index().
2019-07-17 22:16:38 +01:00
if (err)
return err;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
p = data->d_buf;
end = p + data->d_size;
while (p < end) {
nul = memchr(p, 0, end - p);
if (!nul)
break;
libdrgn: fix regression in kernel module loading Commit f32755222965 ("libdrgn: add strstartswith()") flipped the test for a name entry in modinfo. This introduced a regression resulting in kernel modules not loading at the right offset. This patch fixes the regression.
2019-12-13 23:58:34 +00:00
if (strstartswith(p, "name=")) {
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
*ret = p + 5;
return NULL;
}
p = nul + 1;
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
*ret = NULL;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
return NULL;
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
/*
* If the module name isn't in .modinfo, we need to get it from
* .gnu.linkonce.this_module, which contains a struct module. name_offset is
* offsetof(struct module, name).
*/
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
static struct drgn_error *
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
get_kernel_module_name_from_this_module(Elf_Scn *this_module_scn,
size_t name_offset, const char **ret)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
{
struct drgn_error *err;
Elf_Data *data;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
const char *p, *nul;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (this_module_scn) {
err = read_elf_section(this_module_scn, &data);
if (err)
return err;
if (name_offset < data->d_size) {
p = data->d_buf + name_offset;
nul = memchr(p, 0, data->d_size - name_offset);
if (nul && nul != p) {
*ret = p;
return NULL;
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
}
*ret = NULL;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
return NULL;
}
libdrgn: clean up hash function APIs and improve documentation Use *_hash_pair() for hash functions that do the full double hashing and return a struct hash_pair and hash_*() for other hashing utility functions. Also change some of the equality function names to be more symmetric and improve the documentation. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 00:06:23 +01:00
DEFINE_HASH_MAP(elf_scn_name_map, const char *, Elf_Scn *,
c_string_key_hash_pair, c_string_key_eq)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
static struct drgn_error *
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
cache_kernel_module_sections(struct kernel_module_iterator *kmod_it, Elf *elf,
uint64_t *start_ret, uint64_t *end_ret)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
struct drgn_error *err;
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
size_t shstrndx;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (elf_getshdrstrndx(elf, &shstrndx))
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
return drgn_error_libelf();
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
struct elf_scn_name_map scn_map = HASH_TABLE_INIT;
Elf_Scn *scn = NULL;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
while ((scn = elf_nextscn(elf, scn))) {
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr(scn, &shdr_mem);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (!shdr) {
err = drgn_error_libelf();
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
goto out_scn_map;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
libdrgn: really fix failed kernel module symbol lookups It turns out this wasn't a problem with dwfl_addrmodule() at all; the real problem is that .init sections are freed once the module is loaded but we're still considering them for the address range we pass to dwfl_report_module(). Ignore those sections entirely (by omitting them from the section name to section index map). While we're here, let's not bother inserting non-SHF_ALLOC sections in the map.
2019-12-12 21:33:52 +00:00
if (!(shdr->sh_flags & SHF_ALLOC))
continue;
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
struct elf_scn_name_map_entry entry = {
.key = elf_strptr(elf, shstrndx, shdr->sh_name),
.value = scn,
};
libdrgn: handle errors from elf_strptr() For some reason, we consistently ignore errors from elf_strptr(), but we shouldn't. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-03-26 21:28:16 +00:00
if (!entry.key) {
err = drgn_error_libelf();
goto out_scn_map;
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (elf_scn_name_map_insert(&scn_map, &entry, NULL) == -1) {
err = &drgn_enomem;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
goto out_scn_map;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
}
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
uint64_t start = UINT64_MAX, end = 0;
struct kernel_module_section_iterator section_it;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
err = kernel_module_section_iterator_init(&section_it, kmod_it);
if (err)
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
goto out_scn_map;
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
const char *name;
uint64_t address;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
while (!(err = kernel_module_section_iterator_next(&section_it, &name,
&address))) {
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
struct elf_scn_name_map_iterator it =
elf_scn_name_map_search(&scn_map, &name);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (it.entry) {
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr(it.entry->value,
&shdr_mem);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (!shdr) {
err = drgn_error_libelf();
break;
}
shdr->sh_addr = address;
if (!gelf_update_shdr(it.entry->value, shdr)) {
err = drgn_error_libelf();
break;
}
libdrgn: linux_kernel: save module .init section addresses Linux kernel modules usually contain ELF relocations in DWARF and ORC sections for symbols in .init sections. Since we ignore .init sections entirely in cache_kernel_module_sections(), these relocations end up being based on an address of 0 (so, e.g., a function from .init.text could be reported as having an address of 0x0). It makes a little more sense to use the address where the .init section was before it was freed. So, let's update the sections' sh_addr but continue ignoring them for determining the module's address range. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-03-26 21:32:46 +00:00
/*
* .init sections are freed once the module is
* initialized, but they remain in the section list.
* Ignore them for the purpose of determining the
* module's address range.
*/
if (!strstartswith(name, ".init")) {
uint64_t section_end;
if (__builtin_add_overflow(address,
shdr->sh_size,
&section_end))
section_end = UINT64_MAX;
if (address < section_end) {
if (address < start)
start = address;
if (section_end > end)
end = section_end;
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
}
libdrgn: clean up usage of drgn_stop Use drgn_not_found where it's more appropriate, and check explicitly against drgn_stop instead of err->code == DRGN_ERROR_STOP. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-03-05 20:46:06 +00:00
if (err && err != &drgn_stop)
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
goto out_section_it;
err = NULL;
if (start >= end)
start = end = 0;
*start_ret = start;
*end_ret = end;
out_section_it:
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
kernel_module_section_iterator_deinit(&section_it);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
out_scn_map:
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
elf_scn_name_map_deinit(&scn_map);
return err;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
struct kernel_module_file {
const char *path;
int fd;
Elf *elf;
/*
* Kernel module name. This is owned by the Elf handle. Because we use
* this as the key in the kernel_module_table, the file must always be
* removed from the table before it is reported to the DWARF index
* (which takes ownership of the Elf handle).
*/
const char *name;
Elf_Scn *this_module_scn;
/* Next file with the same name. */
struct kernel_module_file *next;
};
static const char *
kernel_module_table_key(struct kernel_module_file * const *entry)
{
return (*entry)->name;
}
DEFINE_HASH_TABLE(kernel_module_table, struct kernel_module_file *,
libdrgn: clean up hash function APIs and improve documentation Use *_hash_pair() for hash functions that do the full double hashing and return a struct hash_pair and hash_*() for other hashing utility functions. Also change some of the equality function names to be more symmetric and improve the documentation. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 00:06:23 +01:00
kernel_module_table_key, c_string_key_hash_pair,
c_string_key_eq)
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
static struct drgn_error *
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
report_loaded_kernel_module(struct drgn_debug_info_load_state *load,
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
struct kernel_module_iterator *kmod_it,
struct kernel_module_table *kmod_table)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
struct drgn_error *err;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
const char *name = kmod_it->name;
struct hash_pair hp = kernel_module_table_hash(&name);
struct kernel_module_table_iterator it =
kernel_module_table_search_hashed(kmod_table, &name, hp);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (!it.entry)
return &drgn_not_found;
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
struct kernel_module_file *kmod = *it.entry;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
kernel_module_table_delete_iterator_hashed(kmod_table, it, hp);
do {
uint64_t start, end;
err = cache_kernel_module_sections(kmod_it, kmod->elf, &start,
&end);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_error(load, kmod->path,
"could not get section addresses",
err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
return err;
libdrgn: fix infinite loop on error caching kernel module sections If cache_kernel_module_sections() in report_loaded_kernel_module() fails, we continue to the next iteration without advancing to the next kernel module. Then, we fail on that same kernel module and repeat. Make sure that we go to the next kernel module. Fixes: 423d2cd5009e ("libdrgn: dwarf_index: rework file reporting") Reported-by: Serapheim Dimitropoulos <serapheim@delphix.com> Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 20:25:22 +01:00
goto next;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_elf(load, kmod->path, kmod->fd,
kmod->elf, start, end,
kmod->name, NULL);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
kmod->elf = NULL;
kmod->fd = -1;
if (err)
return err;
libdrgn: fix infinite loop on error caching kernel module sections If cache_kernel_module_sections() in report_loaded_kernel_module() fails, we continue to the next iteration without advancing to the next kernel module. Then, we fail on that same kernel module and repeat. Make sure that we go to the next kernel module. Fixes: 423d2cd5009e ("libdrgn: dwarf_index: rework file reporting") Reported-by: Serapheim Dimitropoulos <serapheim@delphix.com> Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 20:25:22 +01:00
next:
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
kmod = kmod->next;
} while (kmod);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
return NULL;
}
static struct drgn_error *
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
report_default_kernel_module(struct drgn_debug_info_load_state *load,
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
struct kernel_module_iterator *kmod_it,
struct depmod_index *depmod)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
static const char * const module_paths[] = {
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
"/usr/lib/debug/lib/modules/%s/%.*s",
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
"/usr/lib/debug/lib/modules/%s/%.*s.debug",
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
"/lib/modules/%s/%.*s%.*s",
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
NULL,
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
};
struct drgn_error *err;
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
const char *depmod_path;
size_t depmod_path_len;
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
err = depmod_index_find(depmod, kmod_it->name, &depmod_path,
&depmod_path_len);
if (err) {
return drgn_debug_info_report_error(load,
"kernel modules",
"could not parse depmod",
err);
} else if (!depmod_path) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
return drgn_debug_info_report_error(load, kmod_it->name,
"could not find module in depmod",
NULL);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
size_t extension_len;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (depmod_path_len >= 3 &&
(memcmp(depmod_path + depmod_path_len - 3, ".gz", 3) == 0 ||
memcmp(depmod_path + depmod_path_len - 3, ".xz", 3) == 0))
extension_len = 3;
else
extension_len = 0;
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
char *path;
int fd;
Elf *elf;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
err = find_elf_file(&path, &fd, &elf, module_paths,
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
load->dbinfo->prog->vmcoreinfo.osrelease,
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
depmod_path_len - extension_len, depmod_path,
extension_len,
depmod_path + depmod_path_len - extension_len);
if (err)
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
return drgn_debug_info_report_error(load, NULL, NULL, err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (!elf) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
return drgn_debug_info_report_error(load, kmod_it->name,
"could not find .ko",
NULL);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
uint64_t start, end;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
err = cache_kernel_module_sections(kmod_it, elf, &start, &end);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (err) {
libdrgn: fix use-after-free in kernel module reporting error case We're freeing path and then using it to report an error. This has some weird knock-on effects. Since we freed the path, the error message contains garbage. So, PyErr_SetString() can't decode it as a UTF-8 string. The end result is a MissingDebugInfoError with no message. Fix it by creating the error before freeing the path. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 19:55:06 +01:00
err = drgn_debug_info_report_error(load, path,
"could not get section addresses",
err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
elf_end(elf);
close(fd);
free(path);
libdrgn: fix use-after-free in kernel module reporting error case We're freeing path and then using it to report an error. This has some weird knock-on effects. Since we freed the path, the error message contains garbage. So, PyErr_SetString() can't decode it as a UTF-8 string. The end result is a MissingDebugInfoError with no message. Fix it by creating the error before freeing the path. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 19:55:06 +01:00
return err;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_elf(load, path, fd, elf, start, end,
kmod_it->name, NULL);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
free(path);
return err;
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
static struct drgn_error *
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
report_loaded_kernel_modules(struct drgn_debug_info_load_state *load,
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
struct kernel_module_table *kmod_table,
libdrgn: add an environment variable to disable use of /proc/modules and /sys/module We use /proc/modules and /sys/module to find loaded kernel modules for the running kernel instead of walking the module list in the core dump as an optimization. To make it easier to test the core dump path, add an environment variable to disable the optimization. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 19:24:39 +01:00
struct depmod_index *depmod,
bool use_proc_and_sys)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
struct drgn_program *prog = load->dbinfo->prog;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
struct drgn_error *err;
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
struct kernel_module_iterator kmod_it;
libdrgn: add an environment variable to disable use of /proc/modules and /sys/module We use /proc/modules and /sys/module to find loaded kernel modules for the running kernel instead of walking the module list in the core dump as an optimization. To make it easier to test the core dump path, add an environment variable to disable the optimization. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 19:24:39 +01:00
err = kernel_module_iterator_init(&kmod_it, prog, use_proc_and_sys);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (err) {
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
kernel_module_iterator_error:
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
return drgn_debug_info_report_error(load, "kernel modules",
"could not find loaded kernel modules",
err);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
for (;;) {
err = kernel_module_iterator_next(&kmod_it);
libdrgn: clean up usage of drgn_stop Use drgn_not_found where it's more appropriate, and check explicitly against drgn_stop instead of err->code == DRGN_ERROR_STOP. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-03-05 20:46:06 +00:00
if (err == &drgn_stop) {
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
err = NULL;
break;
} else if (err) {
kernel_module_iterator_deinit(&kmod_it);
goto kernel_module_iterator_error;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
/* Look for an explicitly-reported file first. */
if (kmod_table) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = report_loaded_kernel_module(load, &kmod_it,
kmod_table);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (!err)
continue;
else if (err != &drgn_not_found)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
break;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
}
/*
* If it was not reported explicitly and we're also reporting the
* defaults, look for the module at the standard locations unless we've
* already indexed that module.
*/
if (depmod &&
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
!drgn_debug_info_is_indexed(load->dbinfo, kmod_it.name)) {
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
if (!depmod->addr) {
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
err = depmod_index_init(depmod,
prog->vmcoreinfo.osrelease);
if (err) {
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
depmod->addr = NULL;
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_error(load,
"kernel modules",
"could not read depmod",
err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
break;
depmod = NULL;
continue;
}
}
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = report_default_kernel_module(load, &kmod_it,
depmod);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
if (err)
break;
}
}
kernel_module_iterator_deinit(&kmod_it);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
return err;
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
static struct drgn_error *
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
report_kernel_modules(struct drgn_debug_info_load_state *load,
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
struct kernel_module_file *kmods, size_t num_kmods,
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
bool need_module_definition, bool vmlinux_is_pending)
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
{
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
struct drgn_program *prog = load->dbinfo->prog;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
struct drgn_error *err;
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
if (!num_kmods && !load->load_default)
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
return NULL;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
/*
libdrgn: add an environment variable to disable use of /proc/modules and /sys/module We use /proc/modules and /sys/module to find loaded kernel modules for the running kernel instead of walking the module list in the core dump as an optimization. To make it easier to test the core dump path, add an environment variable to disable the optimization. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 19:24:39 +01:00
* If we're debugging the running kernel, we can get the loaded kernel
* modules from /proc and /sys instead of from the core dump. This fast
* path can be disabled via an environment variable for testing.
*/
bool use_proc_and_sys = false;
if (prog->flags & DRGN_PROGRAM_IS_LIVE) {
char *env = getenv("DRGN_USE_PROC_AND_SYS_MODULES");
use_proc_and_sys = !env || atoi(env);
}
/*
* If we're not using /proc and /sys, then we need to index vmlinux now
* so that we can walk the list of modules in the kernel.
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
*
* If we need the definition of struct module to get the name of any
* kernel modules, then we also need to index vmlinux now.
*/
if (vmlinux_is_pending &&
libdrgn: add an environment variable to disable use of /proc/modules and /sys/module We use /proc/modules and /sys/module to find loaded kernel modules for the running kernel instead of walking the module list in the core dump as an optimization. To make it easier to test the core dump path, add an environment variable to disable the optimization. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 19:24:39 +01:00
(!use_proc_and_sys || need_module_definition)) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_flush(load);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
return err;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
size_t module_name_offset = 0;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (need_module_definition) {
struct drgn_qualified_type module_type;
libdrgn: replace drgn_program_member_info() with drgn_type_find_member() Now that types are associated with their program, we don't need to pass the program separately to drgn_program_member_info() and can replace it with a more natural drgn_type_find_member() API that takes only the type and member name. While we're at it, get rid of drgn_member_info and return the drgn_type_member and bit_offset directly. This also fixes a bug that drgn_error_member_not_found() ignores the member name length. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-15 01:58:44 +00:00
struct drgn_type_member *name_member;
uint64_t name_bit_offset;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
err = drgn_program_find_type(prog, "struct module", NULL,
&module_type);
if (!err) {
libdrgn: replace drgn_program_member_info() with drgn_type_find_member() Now that types are associated with their program, we don't need to pass the program separately to drgn_program_member_info() and can replace it with a more natural drgn_type_find_member() API that takes only the type and member name. While we're at it, get rid of drgn_member_info and return the drgn_type_member and bit_offset directly. This also fixes a bug that drgn_error_member_not_found() ignores the member name length. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-15 01:58:44 +00:00
err = drgn_type_find_member(module_type.type, "name",
&name_member,
&name_bit_offset);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
return drgn_debug_info_report_error(load,
"kernel modules",
"could not get kernel module names",
err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
}
libdrgn: replace drgn_program_member_info() with drgn_type_find_member() Now that types are associated with their program, we don't need to pass the program separately to drgn_program_member_info() and can replace it with a more natural drgn_type_find_member() API that takes only the type and member name. While we're at it, get rid of drgn_member_info and return the drgn_type_member and bit_offset directly. This also fixes a bug that drgn_error_member_not_found() ignores the member name length. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-12-15 01:58:44 +00:00
module_name_offset = name_bit_offset / 8;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
struct kernel_module_table kmod_table = HASH_TABLE_INIT;
struct depmod_index depmod;
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
depmod.addr = NULL;
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
struct kernel_module_table_iterator it;
for (size_t i = 0; i < num_kmods; i++) {
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
struct kernel_module_file *kmod = &kmods[i];
if (!kmod->name) {
err = get_kernel_module_name_from_this_module(kmod->this_module_scn,
module_name_offset,
&kmod->name);
if (err) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_error(load,
kmod->path,
NULL, err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
goto out;
continue;
}
if (!kmod->name) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_error(load,
kmod->path,
"could not find kernel module name",
NULL);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
goto out;
continue;
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: add vector/hash table initializers and update coding style Declaring a local vector or hash table and separately initializing it with vector_init()/hash_table_init() is annoying. Add macros that can be used as initializers. This exposes several places where the C89 style of placing all declarations at the beginning of a block is awkward. I adopted this style from the Linux kernel, which uses C89 and thus requires this style. I'm now convinced that it's usually nicer to declare variables where they're used. So let's officially adopt the style of mixing declarations and code (and ditch the blank line after declarations) and update the functions touched by this change.
2020-07-01 20:37:16 +01:00
struct hash_pair hp = kernel_module_table_hash(&kmod->name);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
it = kernel_module_table_search_hashed(&kmod_table, &kmod->name,
hp);
if (it.entry) {
kmod->next = *it.entry;
*it.entry = kmod;
} else {
if (kernel_module_table_insert_searched(&kmod_table,
&kmod, hp,
NULL) == -1) {
err = &drgn_enomem;
goto out;
}
kmod->next = NULL;
}
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = report_loaded_kernel_modules(load,
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
num_kmods ? &kmod_table : NULL,
libdrgn: add an environment variable to disable use of /proc/modules and /sys/module We use /proc/modules and /sys/module to find loaded kernel modules for the running kernel instead of walking the module list in the core dump as an optimization. To make it easier to test the core dump path, add an environment variable to disable the optimization. Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-13 19:24:39 +01:00
load->load_default ? &depmod : NULL,
use_proc_and_sys);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
if (err)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
goto out;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
/* Anything left over was not loaded. */
for (it = kernel_module_table_first(&kmod_table); it.entry; ) {
struct kernel_module_file *kmod = *it.entry;
it = kernel_module_table_delete_iterator(&kmod_table, it);
do {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_elf(load, kmod->path,
kmod->fd, kmod->elf, 0,
0, kmod->name, NULL);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
kmod->elf = NULL;
kmod->fd = -1;
if (err)
goto out;
kmod = kmod->next;
} while (kmod);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
err = NULL;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
out:
libdrgn: report better errors when parsing DWARF/kmod index If the DWARF index encounters any error while parsing, it returns an error saying only "debug information is truncated", which makes it hard to track down parsing errors. The kmod index parser silently swallows errors. For both, replace the mread functions with a higher-level binary_buffer interface that can include more information including the location of the error. For example: /tmp/mybinary: .debug_info+0x4: expected at least 56 bytes, have 55 Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-10-29 00:35:09 +00:00
if (depmod.addr)
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
depmod_index_deinit(&depmod);
kernel_module_table_deinit(&kmod_table);
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
return err;
}
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
static struct drgn_error *
report_vmlinux(struct drgn_debug_info_load_state *load,
bool *vmlinux_is_pending)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
{
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
static const char * const vmlinux_paths[] = {
/*
* The files under /usr/lib/debug should always have debug
* information, so check for those first.
*/
"/usr/lib/debug/boot/vmlinux-%s",
"/usr/lib/debug/lib/modules/%s/vmlinux",
"/boot/vmlinux-%s",
"/lib/modules/%s/build/vmlinux",
"/lib/modules/%s/vmlinux",
NULL,
};
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
struct drgn_program *prog = load->dbinfo->prog;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
struct drgn_error *err;
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
char *path;
int fd;
Elf *elf;
err = find_elf_file(&path, &fd, &elf, vmlinux_paths,
prog->vmcoreinfo.osrelease);
if (err)
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
return drgn_debug_info_report_error(load, NULL, NULL, err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (!elf) {
err = drgn_error_format(DRGN_ERROR_OTHER,
"could not find vmlinux for %s",
prog->vmcoreinfo.osrelease);
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
return drgn_debug_info_report_error(load, "kernel", NULL, err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
uint64_t start, end;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
err = elf_address_range(elf, prog->vmcoreinfo.kaslr_offset, &start,
&end);
if (err) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_error(load, path, NULL, err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
elf_end(elf);
close(fd);
free(path);
return err;
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
}
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_elf(load, path, fd, elf, start, end,
"kernel", vmlinux_is_pending);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
free(path);
libdrgn: split kernel-specific stuff out of program.c Almost half of program.c is stuff specific to the Linux kernel, so let's separate that out (and combine it with the existing kernel module code).
2019-06-04 23:20:03 +01:00
return err;
}
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
struct drgn_error *
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
linux_kernel_report_debug_info(struct drgn_debug_info_load_state *load)
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
{
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
struct drgn_program *prog = load->dbinfo->prog;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
struct drgn_error *err;
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
struct kernel_module_file *kmods;
if (load->num_paths) {
kmods = malloc_array(load->num_paths, sizeof(*kmods));
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (!kmods)
return &drgn_enomem;
} else {
kmods = NULL;
}
/*
* We may need to index vmlinux before we can properly report kernel
* modules. So, this sets aside kernel modules and reports everything
* else.
*/
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
size_t num_kmods = 0;
bool need_module_definition = false;
bool vmlinux_is_pending = false;
for (size_t i = 0; i < load->num_paths; i++) {
const char *path = load->paths[i];
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
int fd;
Elf *elf;
err = open_elf_file(path, &fd, &elf);
if (err) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_error(load, path, NULL,
err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
goto out;
continue;
}
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
Elf_Scn *this_module_scn, *modinfo_scn;
bool is_vmlinux;
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
err = identify_kernel_elf(elf, &this_module_scn, &modinfo_scn,
&is_vmlinux);
if (err) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_error(load, path, NULL,
err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
elf_end(elf);
close(fd);
if (err)
goto out;
continue;
}
if (this_module_scn || modinfo_scn) {
struct kernel_module_file *kmod = &kmods[num_kmods++];
kmod->path = path;
kmod->fd = fd;
kmod->elf = elf;
err = get_kernel_module_name_from_modinfo(modinfo_scn,
&kmod->name);
if (err) {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_error(load, path,
NULL, err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
goto out;
continue;
}
if (!kmod->name) {
kmod->this_module_scn = this_module_scn;
need_module_definition = true;
}
} else if (is_vmlinux) {
uint64_t start, end;
err = elf_address_range(elf,
prog->vmcoreinfo.kaslr_offset,
&start, &end);
if (err) {
elf_end(elf);
close(fd);
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_error(load, path,
NULL, err);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
goto out;
continue;
}
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
bool is_new;
err = drgn_debug_info_report_elf(load, path, fd, elf,
start, end, "kernel",
&is_new);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
goto out;
if (is_new)
vmlinux_is_pending = true;
} else {
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = drgn_debug_info_report_elf(load, path, fd, elf, 0,
0, NULL, NULL);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
goto out;
}
}
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
if (load->load_main && !vmlinux_is_pending &&
!drgn_debug_info_is_indexed(load->dbinfo, "kernel")) {
err = report_vmlinux(load, &vmlinux_is_pending);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
if (err)
goto out;
}
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
err = report_kernel_modules(load, kmods, num_kmods,
need_module_definition, vmlinux_is_pending);
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
out:
libdrgn: move debugging information tracking into drgn_debug_info Debugging information tracking is currently in two places: drgn_program finds debugging information, and drgn_dwarf_index stores it. Both of these responsibilities make more sense as part of drgn_debug_info, so let's move them there. This prepares us to track extra debugging information that isn't pertinent to indexing. This also reworks a couple of details of loading debugging information: - drgn_dwarf_module and drgn_dwfl_module_userdata are consolidated into a single structure, drgn_debug_info_module. - The first pass of DWARF indexing now happens in parallel with reading compilation units (by using OpenMP tasks). Signed-off-by: Omar Sandoval <osandov@osandov.com>
2020-09-16 01:42:53 +01:00
for (size_t i = 0; i < num_kmods; i++) {
libdrgn: dwarf_index: rework file reporting Currently, the interface between the DWARF index, libdwfl, and the code which finds and reports vmlinux/kernel modules is spaghetti. The DWARF index tracks Dwfl_Modules via their userdata. However, despite conceptually being owned by the DWARF index, the reporting code reports the Dwfl_Modules and sets up the userdata. These Dwfl_Modules and drgn_dwfl_module_userdatas are messy to track and pass between the layers. This reworks the architecture so that the DWARF index owns the Dwfl instance and files are reported to the DWARF index; the DWARF index takes care of reporting to libdwfl internally. In addition to making the interface for the reporter much cleaner, this improves a few things as a side-effect: - We now deduplicate on build ID in addition to path. - We now skip searching for vmlinux and/or kernel modules if they were already indexed. - We now support compressed ELF files via libdwelf. - We can now load default debug info at the same time as additional debug info.
2019-09-25 01:13:53 +01:00
elf_end(kmods[i].elf);
if (kmods[i].fd != -1)
close(kmods[i].fd);
}
free(kmods);
return err;
libdrgn: use libdwfl libdwfl is the elfutils "DWARF frontend library". It has high-level functionality for looking up symbols, walking stack traces, etc. In order to use this functionality, we need to report our debugging information through libdwfl. For userspace programs, libdwfl has a much better implementation than drgn for automatically finding debug information from a core dump or PID. However, for the kernel, libdwfl has a few issues: - It only supports finding debug information for the running kernel, not vmcores. - It determines the vmlinux address range by reading /proc/kallsyms, which is slow (~70ms on my machine). - If separate debug information isn't available for a kernel module, it finds it by walking /lib/modules/$(uname -r)/kernel; this is repeated for every module. - It doesn't find kernel modules with names containing both dashes and underscores (e.g., aes-x86_64). Luckily, drgn already solved all of these problems, and with some effort, we can keep doing it ourselves and report it to libdwfl. The conversion replaces a bunch of code for dealing with userspace core dump notes, /proc/$pid/maps, and relocations.
2019-07-15 08:51:30 +01:00
}
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