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abafdd965f
drgn/libdrgn/debug_info.c
Omar Sandoval abafdd965f 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>
2020-12-14 12:29:17 -08:00

2708 lines
74 KiB
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// Copyright (c) Facebook, Inc. and its affiliates.
// SPDX-License-Identifier: GPL-3.0+
#include <assert.h>
#include <dwarf.h>
#include <elf.h>
#include <elfutils/known-dwarf.h>
#include <elfutils/libdw.h>
#include <elfutils/libdwelf.h>
#include <errno.h>
#include <fcntl.h>
#include <gelf.h>
#include <inttypes.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "debug_info.h"
#include "error.h"
#include "hash_table.h"
#include "language.h"
#include "linux_kernel.h"
#include "object.h"
#include "path.h"
#include "program.h"
#include "type.h"
#include "util.h"
#include "vector.h"
#define DW_TAG_UNKNOWN_FORMAT "unknown DWARF tag 0x%02x"
#define DW_TAG_BUF_LEN (sizeof(DW_TAG_UNKNOWN_FORMAT) - 4 + 2 * sizeof(int))
/**
* Get the name of a DWARF tag.
*
* @return Static string if the tag is known or @p buf if the tag is unknown
* (populated with a description).
*/
static const char *dw_tag_str(int tag, char buf[DW_TAG_BUF_LEN])
{
switch (tag) {
#define DWARF_ONE_KNOWN_DW_TAG(name, value) case value: return "DW_TAG_" #name;
DWARF_ALL_KNOWN_DW_TAG
#undef DWARF_ONE_KNOWN_DW_TAG
default:
sprintf(buf, DW_TAG_UNKNOWN_FORMAT, tag);
return buf;
}
}
/** Like @ref dw_tag_str(), but takes a @c Dwarf_Die. */
static const char *dwarf_tag_str(Dwarf_Die *die, char buf[DW_TAG_BUF_LEN])
{
return dw_tag_str(dwarf_tag(die), buf);
}
static const char * const drgn_debug_scn_names[] = {
[DRGN_SCN_DEBUG_INFO] = ".debug_info",
[DRGN_SCN_DEBUG_ABBREV] = ".debug_abbrev",
[DRGN_SCN_DEBUG_STR] = ".debug_str",
[DRGN_SCN_DEBUG_LINE] = ".debug_line",
};
struct drgn_error *drgn_error_debug_info(struct drgn_debug_info_module *module,
enum drgn_debug_info_scn scn,
const char *ptr, const char *message)
{
const char *name = dwfl_module_info(module->dwfl_module, NULL, NULL,
NULL, NULL, NULL, NULL, NULL);
return drgn_error_format(DRGN_ERROR_OTHER, "%s: %s+%#tx: %s",
name, drgn_debug_scn_names[scn],
ptr - (const char *)module->scns[scn]->d_buf,
message);
}
struct drgn_error *drgn_debug_info_buffer_error(struct binary_buffer *bb,
const char *pos,
const char *message)
{
struct drgn_debug_info_buffer *buffer =
container_of(bb, struct drgn_debug_info_buffer, bb);
return drgn_error_debug_info(buffer->module, buffer->scn, pos, message);
}
DEFINE_VECTOR_FUNCTIONS(drgn_debug_info_module_vector)
static inline struct hash_pair
drgn_debug_info_module_key_hash_pair(const struct drgn_debug_info_module_key *key)
{
size_t hash = hash_bytes(key->build_id, key->build_id_len);
hash = hash_combine(hash, key->start);
hash = hash_combine(hash, key->end);
return hash_pair_from_avalanching_hash(hash);
}
static inline bool
drgn_debug_info_module_key_eq(const struct drgn_debug_info_module_key *a,
const struct drgn_debug_info_module_key *b)
{
return (a->build_id_len == b->build_id_len &&
memcmp(a->build_id, b->build_id, a->build_id_len) == 0 &&
a->start == b->start && a->end == b->end);
}
DEFINE_HASH_TABLE_FUNCTIONS(drgn_debug_info_module_table,
drgn_debug_info_module_key_hash_pair,
drgn_debug_info_module_key_eq)
DEFINE_HASH_TABLE_FUNCTIONS(c_string_set, c_string_key_hash_pair,
c_string_key_eq)
/**
* @c Dwfl_Callbacks::find_elf() implementation.
*
* Ideally we'd use @c dwfl_report_elf() instead, but that doesn't take an @c
* Elf handle, which we need for a couple of reasons:
*
* - We usually already have the @c Elf handle open in order to identify the
* file.
* - For kernel modules, we set the section addresses in the @c Elf handle
* ourselves instead of using @c Dwfl_Callbacks::section_address().
*
* Additionally, there's a special case for vmlinux. It is usually an @c ET_EXEC
* ELF file, but when KASLR is enabled, it needs to be handled like an @c ET_DYN
* file. libdwfl has a hack for this when @c dwfl_report_module() is used, but
* @ref dwfl_report_elf() bypasses this hack.
*
* So, we're stuck using @c dwfl_report_module() and this dummy callback.
*/
static int drgn_dwfl_find_elf(Dwfl_Module *dwfl_module, void **userdatap,
const char *name, Dwarf_Addr base,
char **file_name, Elf **elfp)
{
struct drgn_debug_info_module *module = *userdatap;
/*
* libdwfl consumes the returned path, file descriptor, and ELF handle,
* so clear the fields.
*/
*file_name = module->path;
int fd = module->fd;
*elfp = module->elf;
module->path = NULL;
module->fd = -1;
module->elf = NULL;
return fd;
}
/*
* Uses drgn_dwfl_find_elf() if the ELF file was reported directly and falls
* back to dwfl_linux_proc_find_elf() otherwise.
*/
static int drgn_dwfl_linux_proc_find_elf(Dwfl_Module *dwfl_module,
void **userdatap, const char *name,
Dwarf_Addr base, char **file_name,
Elf **elfp)
{
struct drgn_debug_info_module *module = *userdatap;
if (module->elf) {
return drgn_dwfl_find_elf(dwfl_module, userdatap, name, base,
file_name, elfp);
}
return dwfl_linux_proc_find_elf(dwfl_module, userdatap, name, base,
file_name, elfp);
}
/*
* Uses drgn_dwfl_find_elf() if the ELF file was reported directly and falls
* back to dwfl_build_id_find_elf() otherwise.
*/
static int drgn_dwfl_build_id_find_elf(Dwfl_Module *dwfl_module,
void **userdatap, const char *name,
Dwarf_Addr base, char **file_name,
Elf **elfp)
{
struct drgn_debug_info_module *module = *userdatap;
if (module->elf) {
return drgn_dwfl_find_elf(dwfl_module, userdatap, name, base,
file_name, elfp);
}
return dwfl_build_id_find_elf(dwfl_module, userdatap, name, base,
file_name, elfp);
}
/**
* @c Dwfl_Callbacks::section_address() implementation.
*
* We set the section header @c sh_addr in memory instead of using this, but
* libdwfl requires the callback pointer to be non-@c NULL. It will be called
* for any sections that still have a zero @c sh_addr, meaning they are not
* present in memory.
*/
static int drgn_dwfl_section_address(Dwfl_Module *module, void **userdatap,
const char *name, Dwarf_Addr base,
const char *secname, Elf32_Word shndx,
const GElf_Shdr *shdr, Dwarf_Addr *addr)
{
*addr = -1;
return DWARF_CB_OK;
}
static const Dwfl_Callbacks drgn_dwfl_callbacks = {
.find_elf = drgn_dwfl_find_elf,
.find_debuginfo = dwfl_standard_find_debuginfo,
.section_address = drgn_dwfl_section_address,
};
static const Dwfl_Callbacks drgn_linux_proc_dwfl_callbacks = {
.find_elf = drgn_dwfl_linux_proc_find_elf,
.find_debuginfo = dwfl_standard_find_debuginfo,
.section_address = drgn_dwfl_section_address,
};
static const Dwfl_Callbacks drgn_userspace_core_dump_dwfl_callbacks = {
.find_elf = drgn_dwfl_build_id_find_elf,
.find_debuginfo = dwfl_standard_find_debuginfo,
.section_address = drgn_dwfl_section_address,
};
static void
drgn_debug_info_module_destroy(struct drgn_debug_info_module *module)
{
if (module) {
drgn_error_destroy(module->err);
elf_end(module->elf);
if (module->fd != -1)
close(module->fd);
free(module->path);
free(module->name);
free(module);
}
}
static void
drgn_debug_info_module_finish_indexing(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module)
{
module->state = DRGN_DEBUG_INFO_MODULE_INDEXED;
if (module->name) {
int ret = c_string_set_insert(&dbinfo->module_names,
(const char **)&module->name,
NULL);
/* drgn_debug_info_update_index() should've reserved enough. */
assert(ret != -1);
}
}
struct drgn_dwfl_module_removed_arg {
struct drgn_debug_info *dbinfo;
bool finish_indexing;
bool free_all;
};
static int drgn_dwfl_module_removed(Dwfl_Module *dwfl_module, void *userdatap,
const char *name, Dwarf_Addr base,
void *_arg)
{
struct drgn_dwfl_module_removed_arg *arg = _arg;
/*
* userdatap is actually a void ** like for the other libdwfl callbacks,
* but dwfl_report_end() has the wrong signature for the removed
* callback.
*/
struct drgn_debug_info_module *module = *(void **)userdatap;
if (arg->finish_indexing && module &&
module->state == DRGN_DEBUG_INFO_MODULE_INDEXING)
drgn_debug_info_module_finish_indexing(arg->dbinfo, module);
if (arg->free_all || !module ||
module->state != DRGN_DEBUG_INFO_MODULE_INDEXED) {
drgn_debug_info_module_destroy(module);
} else {
/*
* The module was already indexed. Report it again so libdwfl
* doesn't remove it.
*/
Dwarf_Addr end;
dwfl_module_info(dwfl_module, NULL, NULL, &end, NULL, NULL,
NULL, NULL);
dwfl_report_module(arg->dbinfo->dwfl, name, base, end);
}
return DWARF_CB_OK;
}
static void drgn_debug_info_free_modules(struct drgn_debug_info *dbinfo,
bool finish_indexing, bool free_all)
{
for (struct drgn_debug_info_module_table_iterator it =
drgn_debug_info_module_table_first(&dbinfo->modules); it.entry; ) {
struct drgn_debug_info_module *module = *it.entry;
struct drgn_debug_info_module **nextp = it.entry;
do {
struct drgn_debug_info_module *next = module->next;
if (finish_indexing &&
module->state == DRGN_DEBUG_INFO_MODULE_INDEXING) {
drgn_debug_info_module_finish_indexing(dbinfo,
module);
}
if (free_all ||
module->state != DRGN_DEBUG_INFO_MODULE_INDEXED) {
if (module == *nextp) {
if (nextp == it.entry && !next) {
it = drgn_debug_info_module_table_delete_iterator(&dbinfo->modules,
it);
} else {
if (!next)
it = drgn_debug_info_module_table_next(it);
*nextp = next;
}
}
void **userdatap;
dwfl_module_info(module->dwfl_module,
&userdatap, NULL, NULL, NULL,
NULL, NULL, NULL);
*userdatap = NULL;
drgn_debug_info_module_destroy(module);
} else {
if (!next)
it = drgn_debug_info_module_table_next(it);
nextp = &module->next;
}
module = next;
} while (module);
}
dwfl_report_begin(dbinfo->dwfl);
struct drgn_dwfl_module_removed_arg arg = {
.dbinfo = dbinfo,
.finish_indexing = finish_indexing,
.free_all = free_all,
};
dwfl_report_end(dbinfo->dwfl, drgn_dwfl_module_removed, &arg);
}
struct drgn_error *
drgn_debug_info_report_error(struct drgn_debug_info_load_state *load,
const char *name, const char *message,
struct drgn_error *err)
{
if (err && err->code == DRGN_ERROR_NO_MEMORY) {
/* Always fail hard if we're out of memory. */
goto err;
}
if (load->num_errors == 0 &&
!string_builder_append(&load->errors,
"could not get debugging information for:"))
goto err;
if (load->num_errors < load->max_errors) {
if (!string_builder_line_break(&load->errors))
goto err;
if (name && !string_builder_append(&load->errors, name))
goto err;
if (name && (message || err) &&
!string_builder_append(&load->errors, " ("))
goto err;
if (message && !string_builder_append(&load->errors, message))
goto err;
if (message && err &&
!string_builder_append(&load->errors, ": "))
goto err;
if (err && !string_builder_append_error(&load->errors, err))
goto err;
if (name && (message || err) &&
!string_builder_appendc(&load->errors, ')'))
goto err;
}
load->num_errors++;
drgn_error_destroy(err);
return NULL;
err:
drgn_error_destroy(err);
return &drgn_enomem;
}
static struct drgn_error *
drgn_debug_info_report_module(struct drgn_debug_info_load_state *load,
const void *build_id, size_t build_id_len,
uint64_t start, uint64_t end, const char *name,
Dwfl_Module *dwfl_module, const char *path,
int fd, Elf *elf, bool *new_ret)
{
struct drgn_debug_info *dbinfo = load->dbinfo;
struct drgn_error *err;
char *path_key = NULL;
if (new_ret)
*new_ret = false;
struct hash_pair hp;
struct drgn_debug_info_module_table_iterator it;
if (build_id_len) {
struct drgn_debug_info_module_key key = {
.build_id = build_id,
.build_id_len = build_id_len,
.start = start,
.end = end,
};
hp = drgn_debug_info_module_table_hash(&key);
it = drgn_debug_info_module_table_search_hashed(&dbinfo->modules,
&key, hp);
if (it.entry &&
(*it.entry)->state == DRGN_DEBUG_INFO_MODULE_INDEXED) {
/* We've already indexed this module. */
err = NULL;
goto free;
}
}
if (!dwfl_module) {
path_key = realpath(path, NULL);
if (!path_key) {
path_key = strdup(path);
if (!path_key) {
err = &drgn_enomem;
goto free;
}
}
dwfl_module = dwfl_report_module(dbinfo->dwfl, path_key, start,
end);
if (!dwfl_module) {
err = drgn_error_libdwfl();
goto free;
}
}
void **userdatap;
dwfl_module_info(dwfl_module, &userdatap, NULL, NULL, NULL, NULL, NULL,
NULL);
if (*userdatap) {
/* We've already reported this file at this offset. */
err = NULL;
goto free;
}
if (new_ret)
*new_ret = true;
struct drgn_debug_info_module *module = malloc(sizeof(*module));
if (!module) {
err = &drgn_enomem;
goto free;
}
module->state = DRGN_DEBUG_INFO_MODULE_NEW;
module->build_id = build_id;
module->build_id_len = build_id_len;
module->start = start;
module->end = end;
if (name) {
module->name = strdup(name);
if (!module->name) {
err = &drgn_enomem;
free(module);
goto free;
}
} else {
module->name = NULL;
}
module->dwfl_module = dwfl_module;
memset(module->scns, 0, sizeof(module->scns));
module->path = path_key;
module->fd = fd;
module->elf = elf;
module->err = NULL;
module->next = NULL;
/* path_key, fd and elf are owned by the module now. */
if (!drgn_debug_info_module_vector_append(&load->new_modules,
&module)) {
drgn_debug_info_module_destroy(module);
return &drgn_enomem;
}
if (build_id_len) {
if (it.entry) {
/*
* The first module with this build ID is in
* new_modules, so insert it after in the list, not
* before.
*/
module->next = (*it.entry)->next;
(*it.entry)->next = module;
} else if (drgn_debug_info_module_table_insert_searched(&dbinfo->modules,
&module,
hp,
NULL) < 0) {
load->new_modules.size--;
drgn_debug_info_module_destroy(module);
return &drgn_enomem;
}
}
*userdatap = module;
return NULL;
free:
elf_end(elf);
if (fd != -1)
close(fd);
free(path_key);
return err;
}
struct drgn_error *
drgn_debug_info_report_elf(struct drgn_debug_info_load_state *load,
const char *path, int fd, Elf *elf, uint64_t start,
uint64_t end, const char *name, bool *new_ret)
{
struct drgn_error *err;
const void *build_id;
ssize_t build_id_len = dwelf_elf_gnu_build_id(elf, &build_id);
if (build_id_len < 0) {
err = drgn_debug_info_report_error(load, path, NULL,
drgn_error_libdwfl());
close(fd);
elf_end(elf);
return err;
} else if (build_id_len == 0) {
build_id = NULL;
}
return drgn_debug_info_report_module(load, build_id, build_id_len,
start, end, name, NULL, path, fd,
elf, new_ret);
}
static int drgn_debug_info_report_dwfl_module(Dwfl_Module *dwfl_module,
void **userdatap,
const char *name, Dwarf_Addr base,
void *arg)
{
struct drgn_debug_info_load_state *load = arg;
struct drgn_error *err;
if (*userdatap) {
/*
* This was either reported from drgn_debug_info_report_elf() or
* already indexed.
*/
return DWARF_CB_OK;
}
const unsigned char *build_id;
GElf_Addr build_id_vaddr;
int build_id_len = dwfl_module_build_id(dwfl_module, &build_id,
&build_id_vaddr);
if (build_id_len < 0) {
err = drgn_debug_info_report_error(load, name, NULL,
drgn_error_libdwfl());
if (err)
goto err;
} else if (build_id_len == 0) {
build_id = NULL;
}
Dwarf_Addr end;
dwfl_module_info(dwfl_module, NULL, NULL, &end, NULL, NULL, NULL, NULL);
err = drgn_debug_info_report_module(load, build_id, build_id_len, base,
end, NULL, dwfl_module, name, -1,
NULL, NULL);
if (err)
goto err;
return DWARF_CB_OK;
err:
drgn_error_destroy(err);
return DWARF_CB_ABORT;
}
static struct drgn_error *
userspace_report_debug_info(struct drgn_debug_info_load_state *load)
{
struct drgn_error *err;
for (size_t i = 0; i < load->num_paths; i++) {
int fd;
Elf *elf;
err = open_elf_file(load->paths[i], &fd, &elf);
if (err) {
err = drgn_debug_info_report_error(load, load->paths[i],
NULL, err);
if (err)
return err;
continue;
}
/*
* We haven't implemented a way to get the load address for
* anything reported here, so for now we report it as unloaded.
*/
err = drgn_debug_info_report_elf(load, load->paths[i], fd, elf,
0, 0, NULL, NULL);
if (err)
return err;
}
if (load->load_default) {
Dwfl *dwfl = load->dbinfo->dwfl;
struct drgn_program *prog = load->dbinfo->prog;
if (prog->flags & DRGN_PROGRAM_IS_LIVE) {
int ret = dwfl_linux_proc_report(dwfl, prog->pid);
if (ret == -1) {
return drgn_error_libdwfl();
} else if (ret) {
return drgn_error_create_os("dwfl_linux_proc_report",
ret, NULL);
}
} else if (dwfl_core_file_report(dwfl, prog->core,
NULL) == -1) {
return drgn_error_libdwfl();
}
}
return NULL;
}
static struct drgn_error *apply_relocation(Elf_Data *data, uint64_t r_offset,
uint32_t r_type, int64_t r_addend,
uint64_t st_value)
{
char *p;
p = (char *)data->d_buf + r_offset;
switch (r_type) {
case R_X86_64_NONE:
break;
case R_X86_64_32:
if (r_offset > SIZE_MAX - sizeof(uint32_t) ||
r_offset + sizeof(uint32_t) > data->d_size) {
return drgn_error_create(DRGN_ERROR_OTHER,
"invalid relocation offset");
}
*(uint32_t *)p = st_value + r_addend;
break;
case R_X86_64_64:
if (r_offset > SIZE_MAX - sizeof(uint64_t) ||
r_offset + sizeof(uint64_t) > data->d_size) {
return drgn_error_create(DRGN_ERROR_OTHER,
"invalid relocation offset");
}
*(uint64_t *)p = st_value + r_addend;
break;
default:
return drgn_error_format(DRGN_ERROR_OTHER,
"unimplemented relocation type %" PRIu32,
r_type);
}
return NULL;
}
static struct drgn_error *relocate_section(Elf_Scn *scn, Elf_Scn *rela_scn,
Elf_Scn *symtab_scn,
uint64_t *sh_addrs, size_t shdrnum)
{
struct drgn_error *err;
Elf_Data *data, *rela_data, *symtab_data;
const Elf64_Rela *relocs;
const Elf64_Sym *syms;
size_t num_relocs, num_syms;
size_t i;
GElf_Shdr *shdr, shdr_mem;
err = read_elf_section(scn, &data);
if (err)
return err;
err = read_elf_section(rela_scn, &rela_data);
if (err)
return err;
err = read_elf_section(symtab_scn, &symtab_data);
if (err)
return err;
relocs = (Elf64_Rela *)rela_data->d_buf;
num_relocs = rela_data->d_size / sizeof(Elf64_Rela);
syms = (Elf64_Sym *)symtab_data->d_buf;
num_syms = symtab_data->d_size / sizeof(Elf64_Sym);
for (i = 0; i < num_relocs; i++) {
const Elf64_Rela *reloc = &relocs[i];
uint32_t r_sym, r_type;
uint16_t st_shndx;
uint64_t sh_addr;
r_sym = ELF64_R_SYM(reloc->r_info);
r_type = ELF64_R_TYPE(reloc->r_info);
if (r_sym >= num_syms) {
return drgn_error_create(DRGN_ERROR_OTHER,
"invalid relocation symbol");
}
st_shndx = syms[r_sym].st_shndx;
if (st_shndx == 0) {
sh_addr = 0;
} else if (st_shndx < shdrnum) {
sh_addr = sh_addrs[st_shndx - 1];
} else {
return drgn_error_create(DRGN_ERROR_OTHER,
"invalid symbol section index");
}
err = apply_relocation(data, reloc->r_offset, r_type,
reloc->r_addend,
sh_addr + syms[r_sym].st_value);
if (err)
return err;
}
/*
* Mark the relocation section as empty so that libdwfl doesn't try to
* apply it again.
*/
shdr = gelf_getshdr(rela_scn, &shdr_mem);
if (!shdr)
return drgn_error_libelf();
shdr->sh_size = 0;
if (!gelf_update_shdr(rela_scn, shdr))
return drgn_error_libelf();
rela_data->d_size = 0;
return NULL;
}
/*
* Before the debugging information in a relocatable ELF file (e.g., Linux
* kernel module) can be used, it must have ELF relocations applied. This is
* usually done by libdwfl. However, libdwfl is relatively slow at it. This is a
* much faster implementation. It is only implemented for x86-64; for other
* architectures, we can fall back to libdwfl.
*/
static struct drgn_error *apply_elf_relocations(Elf *elf)
{
struct drgn_error *err;
GElf_Ehdr ehdr_mem, *ehdr;
size_t shdrnum, shstrndx;
uint64_t *sh_addrs;
Elf_Scn *scn;
ehdr = gelf_getehdr(elf, &ehdr_mem);
if (!ehdr)
return drgn_error_libelf();
if (ehdr->e_type != ET_REL ||
ehdr->e_machine != EM_X86_64 ||
ehdr->e_ident[EI_CLASS] != ELFCLASS64 ||
ehdr->e_ident[EI_DATA] !=
(__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ ?
ELFDATA2LSB : ELFDATA2MSB)) {
/* Unsupported; fall back to libdwfl. */
return NULL;
}
if (elf_getshdrnum(elf, &shdrnum))
return drgn_error_libelf();
if (shdrnum > 1) {
sh_addrs = calloc(shdrnum - 1, sizeof(*sh_addrs));
if (!sh_addrs)
return &drgn_enomem;
scn = NULL;
while ((scn = elf_nextscn(elf, scn))) {
size_t ndx;
ndx = elf_ndxscn(scn);
if (ndx > 0 && ndx < shdrnum) {
GElf_Shdr *shdr, shdr_mem;
shdr = gelf_getshdr(scn, &shdr_mem);
if (!shdr) {
err = drgn_error_libelf();
goto out;
}
sh_addrs[ndx - 1] = shdr->sh_addr;
}
}
} else {
sh_addrs = NULL;
}
if (elf_getshdrstrndx(elf, &shstrndx)) {
err = drgn_error_libelf();
goto out;
}
scn = NULL;
while ((scn = elf_nextscn(elf, scn))) {
GElf_Shdr *shdr, shdr_mem;
const char *scnname;
shdr = gelf_getshdr(scn, &shdr_mem);
if (!shdr) {
err = drgn_error_libelf();
goto out;
}
if (shdr->sh_type != SHT_RELA)
continue;
scnname = elf_strptr(elf, shstrndx, shdr->sh_name);
if (!scnname)
continue;
if (strstartswith(scnname, ".rela.debug_")) {
Elf_Scn *info_scn, *link_scn;
info_scn = elf_getscn(elf, shdr->sh_info);
if (!info_scn) {
err = drgn_error_libelf();
goto out;
}
link_scn = elf_getscn(elf, shdr->sh_link);
if (!link_scn) {
err = drgn_error_libelf();
goto out;
}
err = relocate_section(info_scn, scn, link_scn,
sh_addrs, shdrnum);
if (err)
goto out;
}
}
out:
free(sh_addrs);
return NULL;
}
static struct drgn_error *
drgn_get_debug_sections(struct drgn_debug_info_module *module)
{
struct drgn_error *err;
if (module->elf) {
err = apply_elf_relocations(module->elf);
if (err)
return err;
}
/*
* Note: not dwfl_module_getelf(), because then libdwfl applies
* ELF relocations to all sections, not just debug sections.
*/
Dwarf_Addr bias;
Dwarf *dwarf = dwfl_module_getdwarf(module->dwfl_module, &bias);
if (!dwarf)
return drgn_error_libdwfl();
Elf *elf = dwarf_getelf(dwarf);
if (!elf)
return drgn_error_libdw();
module->little_endian = elf_getident(elf, NULL)[EI_DATA] == ELFDATA2LSB;
size_t shstrndx;
if (elf_getshdrstrndx(elf, &shstrndx))
return drgn_error_libelf();
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn(elf, scn))) {
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr(scn, &shdr_mem);
if (!shdr)
return drgn_error_libelf();
if (shdr->sh_type == SHT_NOBITS || (shdr->sh_flags & SHF_GROUP))
continue;
const char *scnname = elf_strptr(elf, shstrndx, shdr->sh_name);
if (!scnname)
continue;
for (size_t i = 0; i < DRGN_NUM_DEBUG_SCNS; i++) {
if (!module->scns[i] &&
strcmp(scnname, drgn_debug_scn_names[i]) == 0) {
err = read_elf_section(scn, &module->scns[i]);
if (err)
return err;
break;
}
}
}
/*
* Truncate any extraneous bytes so that we can assume that a pointer
* within .debug_str is always null-terminated.
*/
Elf_Data *debug_str = module->scns[DRGN_SCN_DEBUG_STR];
if (debug_str) {
const char *buf = debug_str->d_buf;
const char *nul = memrchr(buf, '\0', debug_str->d_size);
if (nul)
debug_str->d_size = nul - buf + 1;
else
debug_str->d_size = 0;
}
return NULL;
}
static struct drgn_error *
drgn_debug_info_read_module(struct drgn_debug_info_load_state *load,
struct drgn_dwarf_index_update_state *dindex_state,
struct drgn_debug_info_module *head)
{
struct drgn_error *err;
struct drgn_debug_info_module *module;
for (module = head; module; module = module->next) {
err = drgn_get_debug_sections(module);
if (err) {
module->err = err;
continue;
}
if (module->scns[DRGN_SCN_DEBUG_INFO] &&
module->scns[DRGN_SCN_DEBUG_ABBREV]) {
module->state = DRGN_DEBUG_INFO_MODULE_INDEXING;
drgn_dwarf_index_read_module(dindex_state, module);
return NULL;
}
}
/*
* We checked all of the files and didn't find debugging information.
* Report why for each one.
*
* (If we did find debugging information, we discard errors on the
* unused files.)
*/
err = NULL;
#pragma omp critical(drgn_debug_info_read_module_error)
for (module = head; module; module = module->next) {
const char *name =
dwfl_module_info(module->dwfl_module, NULL, NULL, NULL,
NULL, NULL, NULL, NULL);
if (module->err) {
err = drgn_debug_info_report_error(load, name, NULL,
module->err);
module->err = NULL;
} else {
err = drgn_debug_info_report_error(load, name,
"no debugging information",
NULL);
}
if (err)
break;
}
return err;
}
static struct drgn_error *
drgn_debug_info_update_index(struct drgn_debug_info_load_state *load)
{
if (!load->new_modules.size)
return NULL;
struct drgn_debug_info *dbinfo = load->dbinfo;
if (!c_string_set_reserve(&dbinfo->module_names,
c_string_set_size(&dbinfo->module_names) +
load->new_modules.size))
return &drgn_enomem;
struct drgn_dwarf_index_update_state dindex_state;
drgn_dwarf_index_update_begin(&dindex_state, &dbinfo->dindex);
/*
* In OpenMP 5.0, this could be "#pragma omp parallel master taskloop"
* (added in GCC 9 and Clang 10).
*/
#pragma omp parallel
#pragma omp master
#pragma omp taskloop
for (size_t i = 0; i < load->new_modules.size; i++) {
if (drgn_dwarf_index_update_cancelled(&dindex_state))
continue;
struct drgn_error *module_err =
drgn_debug_info_read_module(load, &dindex_state,
load->new_modules.data[i]);
if (module_err)
drgn_dwarf_index_update_cancel(&dindex_state, module_err);
}
struct drgn_error *err = drgn_dwarf_index_update_end(&dindex_state);
if (err)
return err;
drgn_debug_info_free_modules(dbinfo, true, false);
return NULL;
}
struct drgn_error *
drgn_debug_info_report_flush(struct drgn_debug_info_load_state *load)
{
struct drgn_debug_info *dbinfo = load->dbinfo;
dwfl_report_end(dbinfo->dwfl, NULL, NULL);
struct drgn_error *err = drgn_debug_info_update_index(load);
dwfl_report_begin_add(dbinfo->dwfl);
if (err)
return err;
load->new_modules.size = 0;
return NULL;
}
static struct drgn_error *
drgn_debug_info_report_finalize_errors(struct drgn_debug_info_load_state *load)
{
if (load->num_errors > load->max_errors &&
(!string_builder_line_break(&load->errors) ||
!string_builder_appendf(&load->errors, "... %u more",
load->num_errors - load->max_errors))) {
free(load->errors.str);
return &drgn_enomem;
}
if (load->num_errors) {
return drgn_error_from_string_builder(DRGN_ERROR_MISSING_DEBUG_INFO,
&load->errors);
} else {
return NULL;
}
}
struct drgn_error *drgn_debug_info_load(struct drgn_debug_info *dbinfo,
const char **paths, size_t n,
bool load_default, bool load_main)
{
struct drgn_program *prog = dbinfo->prog;
struct drgn_error *err;
if (load_default)
load_main = true;
const char *max_errors = getenv("DRGN_MAX_DEBUG_INFO_ERRORS");
struct drgn_debug_info_load_state load = {
.dbinfo = dbinfo,
.paths = paths,
.num_paths = n,
.load_default = load_default,
.load_main = load_main,
.new_modules = VECTOR_INIT,
.max_errors = max_errors ? atoi(max_errors) : 5,
};
dwfl_report_begin_add(dbinfo->dwfl);
if (prog->flags & DRGN_PROGRAM_IS_LINUX_KERNEL)
err = linux_kernel_report_debug_info(&load);
else
err = userspace_report_debug_info(&load);
dwfl_report_end(dbinfo->dwfl, NULL, NULL);
if (err)
goto err;
/*
* userspace_report_debug_info() reports the main debugging information
* directly with libdwfl, so we need to report it to dbinfo.
*/
if (!(prog->flags & DRGN_PROGRAM_IS_LINUX_KERNEL) && load_main &&
dwfl_getmodules(dbinfo->dwfl, drgn_debug_info_report_dwfl_module,
&load, 0)) {
err = &drgn_enomem;
goto err;
}
err = drgn_debug_info_update_index(&load);
if (err)
goto err;
/*
* If this fails, it's too late to roll back. This can only fail with
* enomem, so it's not a big deal.
*/
err = drgn_debug_info_report_finalize_errors(&load);
out:
drgn_debug_info_module_vector_deinit(&load.new_modules);
return err;
err:
drgn_debug_info_free_modules(dbinfo, false, false);
free(load.errors.str);
goto out;
}
bool drgn_debug_info_is_indexed(struct drgn_debug_info *dbinfo,
const char *name)
{
return c_string_set_search(&dbinfo->module_names, &name).entry != NULL;
}
DEFINE_HASH_TABLE_FUNCTIONS(drgn_dwarf_type_map, ptr_key_hash_pair,
scalar_key_eq)
struct drgn_type_from_dwarf_thunk {
struct drgn_type_thunk thunk;
Dwarf_Die die;
bool can_be_incomplete_array;
};
/**
* Return whether a DWARF DIE is little-endian.
*
* @param[in] check_attr Whether to check the DW_AT_endianity attribute. If @c
* false, only the ELF header is checked and this function cannot fail.
* @return @c NULL on success, non-@c NULL on error.
*/
static struct drgn_error *dwarf_die_is_little_endian(Dwarf_Die *die,
bool check_attr, bool *ret)
{
Dwarf_Attribute endianity_attr_mem, *endianity_attr;
Dwarf_Word endianity;
if (check_attr &&
(endianity_attr = dwarf_attr_integrate(die, DW_AT_endianity,
&endianity_attr_mem))) {
if (dwarf_formudata(endianity_attr, &endianity)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"invalid DW_AT_endianity");
}
} else {
endianity = DW_END_default;
}
switch (endianity) {
case DW_END_default: {
Elf *elf = dwarf_getelf(dwarf_cu_getdwarf(die->cu));
*ret = elf_getident(elf, NULL)[EI_DATA] == ELFDATA2LSB;
return NULL;
}
case DW_END_little:
*ret = true;
return NULL;
case DW_END_big:
*ret = false;
return NULL;
default:
return drgn_error_create(DRGN_ERROR_OTHER,
"unknown DW_AT_endianity");
}
}
/** Like dwarf_die_is_little_endian(), but returns a @ref drgn_byte_order. */
static struct drgn_error *dwarf_die_byte_order(Dwarf_Die *die,
bool check_attr,
enum drgn_byte_order *ret)
{
bool little_endian;
struct drgn_error *err = dwarf_die_is_little_endian(die, check_attr,
&little_endian);
/*
* dwarf_die_is_little_endian() can't fail if check_attr is false, so
* the !check_attr test suppresses maybe-uninitialized warnings.
*/
if (!err || !check_attr)
*ret = little_endian ? DRGN_LITTLE_ENDIAN : DRGN_BIG_ENDIAN;
return err;
}
static int dwarf_type(Dwarf_Die *die, Dwarf_Die *ret)
{
Dwarf_Attribute attr_mem;
Dwarf_Attribute *attr;
if (!(attr = dwarf_attr_integrate(die, DW_AT_type, &attr_mem)))
return 1;
return dwarf_formref_die(attr, ret) ? 0 : -1;
}
static int dwarf_flag(Dwarf_Die *die, unsigned int name, bool *ret)
{
Dwarf_Attribute attr_mem;
Dwarf_Attribute *attr;
if (!(attr = dwarf_attr_integrate(die, name, &attr_mem))) {
*ret = false;
return 0;
}
return dwarf_formflag(attr, ret);
}
/**
* Parse a type from a DWARF debugging information entry.
*
* This is the same as @ref drgn_type_from_dwarf() except that it can be used to
* work around a bug in GCC < 9.0 that zero length array types are encoded the
* same as incomplete array types. There are a few places where GCC allows
* zero-length arrays but not incomplete arrays:
*
* - As the type of a member of a structure with only one member.
* - As the type of a structure member other than the last member.
* - As the type of a union member.
* - As the element type of an array.
*
* In these cases, we know that what appears to be an incomplete array type must
* actually have a length of zero. In other cases, a subrange DIE without
* DW_AT_count or DW_AT_upper_bound is ambiguous; we return an incomplete array
* type.
*
* @param[in] dbinfo Debugging information.
* @param[in] die DIE to parse.
* @param[in] can_be_incomplete_array Whether the type can be an incomplete
* array type. If this is @c false and the type appears to be an incomplete
* array type, its length is set to zero instead.
* @param[out] is_incomplete_array_ret Whether the encoded type is an incomplete
* array type or a typedef of an incomplete array type (regardless of @p
* can_be_incomplete_array).
* @param[out] ret Returned type.
* @return @c NULL on success, non-@c NULL on error.
*/
static struct drgn_error *
drgn_type_from_dwarf_internal(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
bool can_be_incomplete_array,
bool *is_incomplete_array_ret,
struct drgn_qualified_type *ret);
/**
* Parse a type from a DWARF debugging information entry.
*
* @param[in] dbinfo Debugging information.
* @param[in] die DIE to parse.
* @param[out] ret Returned type.
* @return @c NULL on success, non-@c NULL on error.
*/
static inline struct drgn_error *
drgn_type_from_dwarf(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
struct drgn_qualified_type *ret)
{
return drgn_type_from_dwarf_internal(dbinfo, die, true, NULL, ret);
}
static struct drgn_error *
drgn_type_from_dwarf_thunk_evaluate_fn(struct drgn_type_thunk *thunk,
struct drgn_qualified_type *ret)
{
struct drgn_type_from_dwarf_thunk *t =
container_of(thunk, struct drgn_type_from_dwarf_thunk, thunk);
return drgn_type_from_dwarf_internal(thunk->prog->_dbinfo, &t->die,
t->can_be_incomplete_array, NULL,
ret);
}
static void drgn_type_from_dwarf_thunk_free_fn(struct drgn_type_thunk *thunk)
{
free(container_of(thunk, struct drgn_type_from_dwarf_thunk, thunk));
}
static struct drgn_error *
drgn_lazy_type_from_dwarf(struct drgn_debug_info *dbinfo, Dwarf_Die *parent_die,
bool can_be_incomplete_array,
struct drgn_lazy_type *ret)
{
char tag_buf[DW_TAG_BUF_LEN];
Dwarf_Attribute attr_mem, *attr;
if (!(attr = dwarf_attr_integrate(parent_die, DW_AT_type, &attr_mem))) {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s is missing DW_AT_type",
dwarf_tag_str(parent_die, tag_buf));
}
Dwarf_Die type_die;
if (!dwarf_formref_die(attr, &type_die)) {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s has invalid DW_AT_type",
dwarf_tag_str(parent_die, tag_buf));
}
struct drgn_type_from_dwarf_thunk *thunk = malloc(sizeof(*thunk));
if (!thunk)
return &drgn_enomem;
thunk->thunk.prog = dbinfo->prog;
thunk->thunk.evaluate_fn = drgn_type_from_dwarf_thunk_evaluate_fn;
thunk->thunk.free_fn = drgn_type_from_dwarf_thunk_free_fn;
thunk->die = type_die;
thunk->can_be_incomplete_array = can_be_incomplete_array;
drgn_lazy_type_init_thunk(ret, &thunk->thunk);
return NULL;
}
/**
* Parse a type from the @c DW_AT_type attribute of a DWARF debugging
* information entry.
*
* @param[in] dbinfo Debugging information.
* @param[in] parent_die Parent DIE.
* @param[in] parent_lang Language of the parent DIE if it is already known, @c
* NULL if it should be determined from @p parent_die.
* @param[in] can_be_void Whether the @c DW_AT_type attribute may be missing,
* which is interpreted as a void type. If this is false and the @c DW_AT_type
* attribute is missing, an error is returned.
* @param[in] can_be_incomplete_array See @ref drgn_type_from_dwarf_internal().
* @param[in] is_incomplete_array_ret See @ref drgn_type_from_dwarf_internal().
* @param[out] ret Returned type.
* @return @c NULL on success, non-@c NULL on error.
*/
static struct drgn_error *
drgn_type_from_dwarf_child(struct drgn_debug_info *dbinfo,
Dwarf_Die *parent_die,
const struct drgn_language *parent_lang,
bool can_be_void, bool can_be_incomplete_array,
bool *is_incomplete_array_ret,
struct drgn_qualified_type *ret)
{
struct drgn_error *err;
char tag_buf[DW_TAG_BUF_LEN];
Dwarf_Attribute attr_mem;
Dwarf_Attribute *attr;
if (!(attr = dwarf_attr_integrate(parent_die, DW_AT_type, &attr_mem))) {
if (can_be_void) {
if (!parent_lang) {
err = drgn_language_from_die(parent_die,
&parent_lang);
if (err)
return err;
}
ret->type = drgn_void_type(dbinfo->prog, parent_lang);
ret->qualifiers = 0;
return NULL;
} else {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s is missing DW_AT_type",
dwarf_tag_str(parent_die,
tag_buf));
}
}
Dwarf_Die type_die;
if (!dwarf_formref_die(attr, &type_die)) {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s has invalid DW_AT_type",
dwarf_tag_str(parent_die, tag_buf));
}
return drgn_type_from_dwarf_internal(dbinfo, &type_die,
can_be_incomplete_array,
is_incomplete_array_ret, ret);
}
static struct drgn_error *
drgn_base_type_from_dwarf(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
const struct drgn_language *lang,
struct drgn_type **ret)
{
const char *name = dwarf_diename(die);
if (!name) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_base_type has missing or invalid DW_AT_name");
}
Dwarf_Attribute attr;
Dwarf_Word encoding;
if (!dwarf_attr_integrate(die, DW_AT_encoding, &attr) ||
dwarf_formudata(&attr, &encoding)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_base_type has missing or invalid DW_AT_encoding");
}
int size = dwarf_bytesize(die);
if (size == -1) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_base_type has missing or invalid DW_AT_byte_size");
}
switch (encoding) {
case DW_ATE_boolean:
return drgn_bool_type_create(dbinfo->prog, name, size, lang,
ret);
case DW_ATE_float:
return drgn_float_type_create(dbinfo->prog, name, size, lang,
ret);
case DW_ATE_signed:
case DW_ATE_signed_char:
return drgn_int_type_create(dbinfo->prog, name, size, true,
lang, ret);
case DW_ATE_unsigned:
case DW_ATE_unsigned_char:
return drgn_int_type_create(dbinfo->prog, name, size, false,
lang, ret);
/*
* GCC also supports complex integer types, but DWARF 4 doesn't have an
* encoding for that. GCC as of 8.2 emits DW_ATE_lo_user, but that's
* ambiguous because it also emits that in other cases. For now, we
* don't support it.
*/
case DW_ATE_complex_float: {
Dwarf_Die child;
if (dwarf_type(die, &child)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_base_type has missing or invalid DW_AT_type");
}
struct drgn_qualified_type real_type;
struct drgn_error *err = drgn_type_from_dwarf(dbinfo, &child,
&real_type);
if (err)
return err;
if (drgn_type_kind(real_type.type) != DRGN_TYPE_FLOAT &&
drgn_type_kind(real_type.type) != DRGN_TYPE_INT) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_AT_type of DW_ATE_complex_float is not a floating-point or integer type");
}
return drgn_complex_type_create(dbinfo->prog, name, size,
real_type.type, lang, ret);
}
default:
return drgn_error_format(DRGN_ERROR_OTHER,
"DW_TAG_base_type has unknown DWARF encoding 0x%llx",
(unsigned long long)encoding);
}
}
/*
* DW_TAG_structure_type, DW_TAG_union_type, DW_TAG_class_type, and
* DW_TAG_enumeration_type can be incomplete (i.e., have a DW_AT_declaration of
* true). This tries to find the complete type. If it succeeds, it returns NULL.
* If it can't find a complete type, it returns a DRGN_ERROR_STOP error.
* Otherwise, it returns an error.
*/
static struct drgn_error *
drgn_debug_info_find_complete(struct drgn_debug_info *dbinfo, uint64_t tag,
const char *name, struct drgn_type **ret)
{
struct drgn_error *err;
struct drgn_dwarf_index_iterator it;
err = drgn_dwarf_index_iterator_init(&it, &dbinfo->dindex.global, name,
strlen(name), &tag, 1);
if (err)
return err;
/*
* Find a matching DIE. Note that drgn_dwarf_index does not contain DIEs
* with DW_AT_declaration, so this will always be a complete type.
*/
struct drgn_dwarf_index_die *index_die =
drgn_dwarf_index_iterator_next(&it);
if (!index_die)
return &drgn_stop;
/*
* Look for another matching DIE. If there is one, then we can't be sure
* which type this is, so leave it incomplete rather than guessing.
*/
if (drgn_dwarf_index_iterator_next(&it))
return &drgn_stop;
Dwarf_Die die;
err = drgn_dwarf_index_get_die(index_die, &die, NULL);
if (err)
return err;
struct drgn_qualified_type qualified_type;
err = drgn_type_from_dwarf(dbinfo, &die, &qualified_type);
if (err)
return err;
*ret = qualified_type.type;
return NULL;
}
static struct drgn_error *
parse_member_offset(Dwarf_Die *die, struct drgn_lazy_type *member_type,
uint64_t bit_field_size, bool little_endian, uint64_t *ret)
{
struct drgn_error *err;
Dwarf_Attribute attr_mem;
Dwarf_Attribute *attr;
/*
* The simplest case is when we have DW_AT_data_bit_offset, which is
* already the offset in bits from the beginning of the containing
* object to the beginning of the member (which may be a bit field).
*/
attr = dwarf_attr_integrate(die, DW_AT_data_bit_offset, &attr_mem);
if (attr) {
Dwarf_Word bit_offset;
if (dwarf_formudata(attr, &bit_offset)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_member has invalid DW_AT_data_bit_offset");
}
*ret = bit_offset;
return NULL;
}
/*
* Otherwise, we might have DW_AT_data_member_location, which is the
* offset in bytes from the beginning of the containing object.
*/
attr = dwarf_attr_integrate(die, DW_AT_data_member_location, &attr_mem);
if (attr) {
Dwarf_Word byte_offset;
if (dwarf_formudata(attr, &byte_offset)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_member has invalid DW_AT_data_member_location");
}
*ret = 8 * byte_offset;
} else {
*ret = 0;
}
/*
* In addition to DW_AT_data_member_location, a bit field might have
* DW_AT_bit_offset, which is the offset in bits of the most significant
* bit of the bit field from the most significant bit of the containing
* object.
*/
attr = dwarf_attr_integrate(die, DW_AT_bit_offset, &attr_mem);
if (attr) {
Dwarf_Word bit_offset;
if (dwarf_formudata(attr, &bit_offset)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_member has invalid DW_AT_bit_offset");
}
/*
* If the architecture is little-endian, then we must compute
* the location of the most significant bit from the size of the
* member, then subtract the bit offset and bit size to get the
* location of the beginning of the bit field.
*
* If the architecture is big-endian, then the most significant
* bit of the bit field is the beginning.
*/
if (little_endian) {
uint64_t byte_size;
attr = dwarf_attr_integrate(die, DW_AT_byte_size,
&attr_mem);
/*
* If the member has an explicit byte size, we can use
* that. Otherwise, we have to get it from the member
* type.
*/
if (attr) {
Dwarf_Word word;
if (dwarf_formudata(attr, &word)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_member has invalid DW_AT_byte_size");
}
byte_size = word;
} else {
struct drgn_qualified_type containing_type;
err = drgn_lazy_type_evaluate(member_type,
&containing_type);
if (err)
return err;
if (!drgn_type_has_size(containing_type.type)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_member bit field type does not have size");
}
byte_size = drgn_type_size(containing_type.type);
}
*ret += 8 * byte_size - bit_offset - bit_field_size;
} else {
*ret += bit_offset;
}
}
return NULL;
}
static struct drgn_error *
parse_member(struct drgn_debug_info *dbinfo, Dwarf_Die *die, bool little_endian,
bool can_be_incomplete_array,
struct drgn_compound_type_builder *builder)
{
Dwarf_Attribute attr_mem, *attr;
const char *name;
if ((attr = dwarf_attr_integrate(die, DW_AT_name, &attr_mem))) {
name = dwarf_formstring(attr);
if (!name) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_member has invalid DW_AT_name");
}
} else {
name = NULL;
}
uint64_t bit_field_size;
if ((attr = dwarf_attr_integrate(die, DW_AT_bit_size, &attr_mem))) {
Dwarf_Word bit_size;
if (dwarf_formudata(attr, &bit_size)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_member has invalid DW_AT_bit_size");
}
bit_field_size = bit_size;
} else {
bit_field_size = 0;
}
struct drgn_lazy_type member_type;
struct drgn_error *err = drgn_lazy_type_from_dwarf(dbinfo, die,
can_be_incomplete_array,
&member_type);
if (err)
return err;
uint64_t bit_offset;
err = parse_member_offset(die, &member_type, bit_field_size,
little_endian, &bit_offset);
if (err)
goto err;
err = drgn_compound_type_builder_add_member(builder, member_type, name,
bit_offset, bit_field_size);
if (err)
goto err;
return NULL;
err:
drgn_lazy_type_deinit(&member_type);
return err;
}
static struct drgn_error *
drgn_compound_type_from_dwarf(struct drgn_debug_info *dbinfo,
Dwarf_Die *die, const struct drgn_language *lang,
enum drgn_type_kind kind, struct drgn_type **ret)
{
struct drgn_error *err;
char tag_buf[DW_TAG_BUF_LEN];
Dwarf_Attribute attr_mem;
Dwarf_Attribute *attr = dwarf_attr_integrate(die, DW_AT_name,
&attr_mem);
const char *tag;
if (attr) {
tag = dwarf_formstring(attr);
if (!tag) {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s has invalid DW_AT_name",
dwarf_tag_str(die, tag_buf));
}
} else {
tag = NULL;
}
bool declaration;
if (dwarf_flag(die, DW_AT_declaration, &declaration)) {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s has invalid DW_AT_declaration",
dwarf_tag_str(die, tag_buf));
}
if (declaration && tag) {
err = drgn_debug_info_find_complete(dbinfo, dwarf_tag(die), tag,
ret);
if (!err || err->code != DRGN_ERROR_STOP)
return err;
}
if (declaration) {
return drgn_incomplete_compound_type_create(dbinfo->prog, kind,
tag, lang, ret);
}
int size = dwarf_bytesize(die);
if (size == -1) {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s has missing or invalid DW_AT_byte_size",
dwarf_tag_str(die, tag_buf));
}
struct drgn_compound_type_builder builder;
drgn_compound_type_builder_init(&builder, dbinfo->prog, kind);
bool little_endian;
dwarf_die_is_little_endian(die, false, &little_endian);
Dwarf_Die member = {}, child;
int r = dwarf_child(die, &child);
while (r == 0) {
if (dwarf_tag(&child) == DW_TAG_member) {
if (member.addr) {
err = parse_member(dbinfo, &member,
little_endian, false,
&builder);
if (err)
goto err;
}
member = child;
}
r = dwarf_siblingof(&child, &child);
}
if (r == -1) {
err = drgn_error_create(DRGN_ERROR_OTHER,
"libdw could not parse DIE children");
goto err;
}
/*
* Flexible array members are only allowed as the last member of a
* structure with at least one other member.
*/
if (member.addr) {
err = parse_member(dbinfo, &member, little_endian,
kind != DRGN_TYPE_UNION &&
builder.members.size > 0,
&builder);
if (err)
goto err;
}
err = drgn_compound_type_create(&builder, tag, size, lang, ret);
if (err)
goto err;
return NULL;
err:
drgn_compound_type_builder_deinit(&builder);
return err;
}
static struct drgn_error *
parse_enumerator(Dwarf_Die *die, struct drgn_enum_type_builder *builder,
bool *is_signed)
{
const char *name = dwarf_diename(die);
if (!name) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_enumerator has missing or invalid DW_AT_name");
}
Dwarf_Attribute attr_mem, *attr;
if (!(attr = dwarf_attr_integrate(die, DW_AT_const_value, &attr_mem))) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_enumerator is missing DW_AT_const_value");
}
struct drgn_error *err;
if (attr->form == DW_FORM_sdata ||
attr->form == DW_FORM_implicit_const) {
Dwarf_Sword svalue;
if (dwarf_formsdata(attr, &svalue))
goto invalid;
err = drgn_enum_type_builder_add_signed(builder, name,
svalue);
/*
* GCC before 7.1 didn't include DW_AT_encoding for
* DW_TAG_enumeration_type DIEs, so we have to guess the sign
* for enum_compatible_type_fallback().
*/
if (!err && svalue < 0)
*is_signed = true;
} else {
Dwarf_Word uvalue;
if (dwarf_formudata(attr, &uvalue))
goto invalid;
err = drgn_enum_type_builder_add_unsigned(builder, name,
uvalue);
}
return err;
invalid:
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_enumerator has invalid DW_AT_const_value");
}
/*
* GCC before 5.1 did not include DW_AT_type for DW_TAG_enumeration_type DIEs,
* so we have to fabricate the compatible type.
*/
static struct drgn_error *
enum_compatible_type_fallback(struct drgn_debug_info *dbinfo,
Dwarf_Die *die, bool is_signed,
const struct drgn_language *lang,
struct drgn_type **ret)
{
int size = dwarf_bytesize(die);
if (size == -1) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_enumeration_type has missing or invalid DW_AT_byte_size");
}
return drgn_int_type_create(dbinfo->prog, "<unknown>", size, is_signed,
lang, ret);
}
static struct drgn_error *
drgn_enum_type_from_dwarf(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
const struct drgn_language *lang,
struct drgn_type **ret)
{
struct drgn_error *err;
Dwarf_Attribute attr_mem;
Dwarf_Attribute *attr = dwarf_attr_integrate(die, DW_AT_name,
&attr_mem);
const char *tag;
if (attr) {
tag = dwarf_formstring(attr);
if (!tag)
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_enumeration_type has invalid DW_AT_name");
} else {
tag = NULL;
}
bool declaration;
if (dwarf_flag(die, DW_AT_declaration, &declaration)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_enumeration_type has invalid DW_AT_declaration");
}
if (declaration && tag) {
err = drgn_debug_info_find_complete(dbinfo,
DW_TAG_enumeration_type,
tag, ret);
if (!err || err->code != DRGN_ERROR_STOP)
return err;
}
if (declaration) {
return drgn_incomplete_enum_type_create(dbinfo->prog, tag, lang,
ret);
}
struct drgn_enum_type_builder builder;
drgn_enum_type_builder_init(&builder, dbinfo->prog);
bool is_signed = false;
Dwarf_Die child;
int r = dwarf_child(die, &child);
while (r == 0) {
if (dwarf_tag(&child) == DW_TAG_enumerator) {
err = parse_enumerator(&child, &builder, &is_signed);
if (err)
goto err;
}
r = dwarf_siblingof(&child, &child);
}
if (r == -1) {
err = drgn_error_create(DRGN_ERROR_OTHER,
"libdw could not parse DIE children");
goto err;
}
struct drgn_type *compatible_type;
r = dwarf_type(die, &child);
if (r == -1) {
err = drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_enumeration_type has invalid DW_AT_type");
goto err;
} else if (r) {
err = enum_compatible_type_fallback(dbinfo, die, is_signed,
lang, &compatible_type);
if (err)
goto err;
} else {
struct drgn_qualified_type qualified_compatible_type;
err = drgn_type_from_dwarf(dbinfo, &child,
&qualified_compatible_type);
if (err)
goto err;
compatible_type = qualified_compatible_type.type;
if (drgn_type_kind(compatible_type) != DRGN_TYPE_INT) {
err = drgn_error_create(DRGN_ERROR_OTHER,
"DW_AT_type of DW_TAG_enumeration_type is not an integer type");
goto err;
}
}
err = drgn_enum_type_create(&builder, tag, compatible_type, lang, ret);
if (err)
goto err;
return NULL;
err:
drgn_enum_type_builder_deinit(&builder);
return err;
}
static struct drgn_error *
drgn_typedef_type_from_dwarf(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
const struct drgn_language *lang,
bool can_be_incomplete_array,
bool *is_incomplete_array_ret,
struct drgn_type **ret)
{
const char *name = dwarf_diename(die);
if (!name) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_typedef has missing or invalid DW_AT_name");
}
struct drgn_qualified_type aliased_type;
struct drgn_error *err = drgn_type_from_dwarf_child(dbinfo, die,
drgn_language_or_default(lang),
true,
can_be_incomplete_array,
is_incomplete_array_ret,
&aliased_type);
if (err)
return err;
return drgn_typedef_type_create(dbinfo->prog, name, aliased_type, lang,
ret);
}
static struct drgn_error *
drgn_pointer_type_from_dwarf(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
const struct drgn_language *lang,
struct drgn_type **ret)
{
struct drgn_qualified_type referenced_type;
struct drgn_error *err = drgn_type_from_dwarf_child(dbinfo, die,
drgn_language_or_default(lang),
true, true, NULL,
&referenced_type);
if (err)
return err;
Dwarf_Attribute attr_mem, *attr;
uint64_t size;
if ((attr = dwarf_attr_integrate(die, DW_AT_byte_size, &attr_mem))) {
Dwarf_Word word;
if (dwarf_formudata(attr, &word)) {
return drgn_error_format(DRGN_ERROR_OTHER,
"DW_TAG_pointer_type has invalid DW_AT_byte_size");
}
size = word;
} else {
uint8_t word_size;
err = drgn_program_word_size(dbinfo->prog, &word_size);
if (err)
return err;
size = word_size;
}
return drgn_pointer_type_create(dbinfo->prog, referenced_type, size,
lang, ret);
}
struct array_dimension {
uint64_t length;
bool is_complete;
};
DEFINE_VECTOR(array_dimension_vector, struct array_dimension)
static struct drgn_error *subrange_length(Dwarf_Die *die,
struct array_dimension *dimension)
{
Dwarf_Attribute attr_mem;
Dwarf_Attribute *attr;
Dwarf_Word word;
if (!(attr = dwarf_attr_integrate(die, DW_AT_upper_bound, &attr_mem)) &&
!(attr = dwarf_attr_integrate(die, DW_AT_count, &attr_mem))) {
dimension->is_complete = false;
return NULL;
}
if (dwarf_formudata(attr, &word)) {
return drgn_error_format(DRGN_ERROR_OTHER,
"DW_TAG_subrange_type has invalid %s",
attr->code == DW_AT_upper_bound ?
"DW_AT_upper_bound" :
"DW_AT_count");
}
dimension->is_complete = true;
/*
* GCC emits a DW_FORM_sdata DW_AT_upper_bound of -1 for empty array
* variables without an explicit size (e.g., `int arr[] = {};`).
*/
if (attr->code == DW_AT_upper_bound && attr->form == DW_FORM_sdata &&
word == (Dwarf_Word)-1) {
dimension->length = 0;
} else if (attr->code == DW_AT_upper_bound) {
if (word >= UINT64_MAX) {
return drgn_error_create(DRGN_ERROR_OVERFLOW,
"DW_AT_upper_bound is too large");
}
dimension->length = (uint64_t)word + 1;
} else {
if (word > UINT64_MAX) {
return drgn_error_create(DRGN_ERROR_OVERFLOW,
"DW_AT_count is too large");
}
dimension->length = word;
}
return NULL;
}
static struct drgn_error *
drgn_array_type_from_dwarf(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
const struct drgn_language *lang,
bool can_be_incomplete_array,
bool *is_incomplete_array_ret,
struct drgn_type **ret)
{
struct drgn_error *err;
struct array_dimension_vector dimensions = VECTOR_INIT;
struct array_dimension *dimension;
Dwarf_Die child;
int r = dwarf_child(die, &child);
while (r == 0) {
if (dwarf_tag(&child) == DW_TAG_subrange_type) {
dimension = array_dimension_vector_append_entry(&dimensions);
if (!dimension)
goto out;
err = subrange_length(&child, dimension);
if (err)
goto out;
}
r = dwarf_siblingof(&child, &child);
}
if (r == -1) {
err = drgn_error_create(DRGN_ERROR_OTHER,
"libdw could not parse DIE children");
goto out;
}
if (!dimensions.size) {
dimension = array_dimension_vector_append_entry(&dimensions);
if (!dimension)
goto out;
dimension->is_complete = false;
}
struct drgn_qualified_type element_type;
err = drgn_type_from_dwarf_child(dbinfo, die,
drgn_language_or_default(lang), false,
false, NULL, &element_type);
if (err)
goto out;
*is_incomplete_array_ret = !dimensions.data[0].is_complete;
struct drgn_type *type;
do {
dimension = array_dimension_vector_pop(&dimensions);
if (dimension->is_complete) {
err = drgn_array_type_create(dbinfo->prog, element_type,
dimension->length, lang,
&type);
} else if (dimensions.size || !can_be_incomplete_array) {
err = drgn_array_type_create(dbinfo->prog, element_type,
0, lang, &type);
} else {
err = drgn_incomplete_array_type_create(dbinfo->prog,
element_type,
lang, &type);
}
if (err)
goto out;
element_type.type = type;
element_type.qualifiers = 0;
} while (dimensions.size);
*ret = type;
err = NULL;
out:
array_dimension_vector_deinit(&dimensions);
return err;
}
static struct drgn_error *
parse_formal_parameter(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
struct drgn_function_type_builder *builder)
{
Dwarf_Attribute attr_mem, *attr;
const char *name;
if ((attr = dwarf_attr_integrate(die, DW_AT_name, &attr_mem))) {
name = dwarf_formstring(attr);
if (!name) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_formal_parameter has invalid DW_AT_name");
}
} else {
name = NULL;
}
struct drgn_lazy_type parameter_type;
struct drgn_error *err = drgn_lazy_type_from_dwarf(dbinfo, die, true,
&parameter_type);
if (err)
return err;
err = drgn_function_type_builder_add_parameter(builder, parameter_type,
name);
if (err)
drgn_lazy_type_deinit(&parameter_type);
return err;
}
static struct drgn_error *
drgn_function_type_from_dwarf(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
const struct drgn_language *lang,
struct drgn_type **ret)
{
struct drgn_error *err;
char tag_buf[DW_TAG_BUF_LEN];
struct drgn_function_type_builder builder;
drgn_function_type_builder_init(&builder, dbinfo->prog);
bool is_variadic = false;
Dwarf_Die child;
int r = dwarf_child(die, &child);
while (r == 0) {
switch (dwarf_tag(&child)) {
case DW_TAG_formal_parameter:
if (is_variadic) {
err = drgn_error_format(DRGN_ERROR_OTHER,
"%s has DW_TAG_formal_parameter child after DW_TAG_unspecified_parameters child",
dwarf_tag_str(die,
tag_buf));
goto err;
}
err = parse_formal_parameter(dbinfo, &child, &builder);
if (err)
goto err;
break;
case DW_TAG_unspecified_parameters:
if (is_variadic) {
err = drgn_error_format(DRGN_ERROR_OTHER,
"%s has multiple DW_TAG_unspecified_parameters children",
dwarf_tag_str(die,
tag_buf));
goto err;
}
is_variadic = true;
break;
default:
break;
}
r = dwarf_siblingof(&child, &child);
}
if (r == -1) {
err = drgn_error_create(DRGN_ERROR_OTHER,
"libdw could not parse DIE children");
goto err;
}
struct drgn_qualified_type return_type;
err = drgn_type_from_dwarf_child(dbinfo, die,
drgn_language_or_default(lang), true,
true, NULL, &return_type);
if (err)
goto err;
err = drgn_function_type_create(&builder, return_type, is_variadic,
lang, ret);
if (err)
goto err;
return NULL;
err:
drgn_function_type_builder_deinit(&builder);
return err;
}
static struct drgn_error *
drgn_type_from_dwarf_internal(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
bool can_be_incomplete_array,
bool *is_incomplete_array_ret,
struct drgn_qualified_type *ret)
{
if (dbinfo->depth >= 1000) {
return drgn_error_create(DRGN_ERROR_RECURSION,
"maximum DWARF type parsing depth exceeded");
}
struct drgn_dwarf_type_map_entry entry = {
.key = die->addr,
};
struct hash_pair hp = drgn_dwarf_type_map_hash(&entry.key);
struct drgn_dwarf_type_map_iterator it =
drgn_dwarf_type_map_search_hashed(&dbinfo->types, &entry.key,
hp);
if (it.entry) {
if (!can_be_incomplete_array &&
it.entry->value.is_incomplete_array) {
it = drgn_dwarf_type_map_search_hashed(&dbinfo->cant_be_incomplete_array_types,
&entry.key, hp);
}
if (it.entry) {
ret->type = it.entry->value.type;
ret->qualifiers = it.entry->value.qualifiers;
return NULL;
}
}
const struct drgn_language *lang;
struct drgn_error *err = drgn_language_from_die(die, &lang);
if (err)
return err;
ret->qualifiers = 0;
dbinfo->depth++;
entry.value.is_incomplete_array = false;
switch (dwarf_tag(die)) {
case DW_TAG_const_type:
err = drgn_type_from_dwarf_child(dbinfo, die,
drgn_language_or_default(lang),
true, true, NULL, ret);
ret->qualifiers |= DRGN_QUALIFIER_CONST;
break;
case DW_TAG_restrict_type:
err = drgn_type_from_dwarf_child(dbinfo, die,
drgn_language_or_default(lang),
true, true, NULL, ret);
ret->qualifiers |= DRGN_QUALIFIER_RESTRICT;
break;
case DW_TAG_volatile_type:
err = drgn_type_from_dwarf_child(dbinfo, die,
drgn_language_or_default(lang),
true, true, NULL, ret);
ret->qualifiers |= DRGN_QUALIFIER_VOLATILE;
break;
case DW_TAG_atomic_type:
err = drgn_type_from_dwarf_child(dbinfo, die,
drgn_language_or_default(lang),
true, true, NULL, ret);
ret->qualifiers |= DRGN_QUALIFIER_ATOMIC;
break;
case DW_TAG_base_type:
err = drgn_base_type_from_dwarf(dbinfo, die, lang, &ret->type);
break;
case DW_TAG_structure_type:
err = drgn_compound_type_from_dwarf(dbinfo, die, lang,
DRGN_TYPE_STRUCT,
&ret->type);
break;
case DW_TAG_union_type:
err = drgn_compound_type_from_dwarf(dbinfo, die, lang,
DRGN_TYPE_UNION,
&ret->type);
break;
case DW_TAG_class_type:
err = drgn_compound_type_from_dwarf(dbinfo, die, lang,
DRGN_TYPE_CLASS,
&ret->type);
break;
case DW_TAG_enumeration_type:
err = drgn_enum_type_from_dwarf(dbinfo, die, lang, &ret->type);
break;
case DW_TAG_typedef:
err = drgn_typedef_type_from_dwarf(dbinfo, die, lang,
can_be_incomplete_array,
&entry.value.is_incomplete_array,
&ret->type);
break;
case DW_TAG_pointer_type:
err = drgn_pointer_type_from_dwarf(dbinfo, die, lang,
&ret->type);
break;
case DW_TAG_array_type:
err = drgn_array_type_from_dwarf(dbinfo, die, lang,
can_be_incomplete_array,
&entry.value.is_incomplete_array,
&ret->type);
break;
case DW_TAG_subroutine_type:
case DW_TAG_subprogram:
err = drgn_function_type_from_dwarf(dbinfo, die, lang,
&ret->type);
break;
default:
err = drgn_error_format(DRGN_ERROR_OTHER,
"unknown DWARF type tag 0x%x",
dwarf_tag(die));
break;
}
dbinfo->depth--;
if (err)
return err;
entry.value.type = ret->type;
entry.value.qualifiers = ret->qualifiers;
struct drgn_dwarf_type_map *map;
if (!can_be_incomplete_array && entry.value.is_incomplete_array)
map = &dbinfo->cant_be_incomplete_array_types;
else
map = &dbinfo->types;
if (drgn_dwarf_type_map_insert_searched(map, &entry, hp, NULL) == -1) {
/*
* This will "leak" the type we created, but it'll still be
* cleaned up when the program is freed.
*/
return &drgn_enomem;
}
if (is_incomplete_array_ret)
*is_incomplete_array_ret = entry.value.is_incomplete_array;
return NULL;
}
struct drgn_error *drgn_debug_info_find_type(enum drgn_type_kind kind,
const char *name, size_t name_len,
const char *filename, void *arg,
struct drgn_qualified_type *ret)
{
struct drgn_error *err;
struct drgn_debug_info *dbinfo = arg;
uint64_t tag;
switch (kind) {
case DRGN_TYPE_INT:
case DRGN_TYPE_BOOL:
case DRGN_TYPE_FLOAT:
tag = DW_TAG_base_type;
break;
case DRGN_TYPE_STRUCT:
tag = DW_TAG_structure_type;
break;
case DRGN_TYPE_UNION:
tag = DW_TAG_union_type;
break;
case DRGN_TYPE_CLASS:
tag = DW_TAG_class_type;
break;
case DRGN_TYPE_ENUM:
tag = DW_TAG_enumeration_type;
break;
case DRGN_TYPE_TYPEDEF:
tag = DW_TAG_typedef;
break;
default:
UNREACHABLE();
}
struct drgn_dwarf_index_iterator it;
err = drgn_dwarf_index_iterator_init(&it, &dbinfo->dindex.global, name,
name_len, &tag, 1);
if (err)
return err;
struct drgn_dwarf_index_die *index_die;
while ((index_die = drgn_dwarf_index_iterator_next(&it))) {
Dwarf_Die die;
err = drgn_dwarf_index_get_die(index_die, &die, NULL);
if (err)
return err;
if (die_matches_filename(&die, filename)) {
err = drgn_type_from_dwarf(dbinfo, &die, ret);
if (err)
return err;
/*
* For DW_TAG_base_type, we need to check that the type
* we found was the right kind.
*/
if (drgn_type_kind(ret->type) == kind)
return NULL;
}
}
return &drgn_not_found;
}
static struct drgn_error *
drgn_object_from_dwarf_enumerator(struct drgn_debug_info *dbinfo,
Dwarf_Die *die, const char *name,
struct drgn_object *ret)
{
struct drgn_error *err;
struct drgn_qualified_type qualified_type;
const struct drgn_type_enumerator *enumerators;
size_t num_enumerators, i;
err = drgn_type_from_dwarf(dbinfo, die, &qualified_type);
if (err)
return err;
enumerators = drgn_type_enumerators(qualified_type.type);
num_enumerators = drgn_type_num_enumerators(qualified_type.type);
for (i = 0; i < num_enumerators; i++) {
if (strcmp(enumerators[i].name, name) != 0)
continue;
if (drgn_enum_type_is_signed(qualified_type.type)) {
return drgn_object_set_signed(ret, qualified_type,
enumerators[i].svalue, 0);
} else {
return drgn_object_set_unsigned(ret, qualified_type,
enumerators[i].uvalue,
0);
}
}
UNREACHABLE();
}
static struct drgn_error *
drgn_object_from_dwarf_subprogram(struct drgn_debug_info *dbinfo,
Dwarf_Die *die, uint64_t bias,
const char *name, struct drgn_object *ret)
{
struct drgn_qualified_type qualified_type;
struct drgn_error *err = drgn_type_from_dwarf(dbinfo, die,
&qualified_type);
if (err)
return err;
Dwarf_Addr low_pc;
if (dwarf_lowpc(die, &low_pc) == -1)
return drgn_object_set_unavailable(ret, qualified_type, 0);
enum drgn_byte_order byte_order;
dwarf_die_byte_order(die, false, &byte_order);
return drgn_object_set_reference(ret, qualified_type, low_pc + bias, 0,
0, byte_order);
}
static struct drgn_error *
drgn_object_from_dwarf_constant(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
struct drgn_qualified_type qualified_type,
Dwarf_Attribute *attr, struct drgn_object *ret)
{
struct drgn_object_type type;
enum drgn_object_encoding encoding;
uint64_t bit_size;
struct drgn_error *err = drgn_object_set_common(qualified_type, 0,
&type, &encoding,
&bit_size);
if (err)
return err;
Dwarf_Block block;
if (dwarf_formblock(attr, &block) == 0) {
bool little_endian;
err = dwarf_die_is_little_endian(die, true, &little_endian);
if (err)
return err;
if (block.length < drgn_value_size(bit_size)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_AT_const_value block is too small");
}
return drgn_object_set_from_buffer_internal(ret, &type,
encoding, bit_size,
block.data, 0,
little_endian);
} else if (encoding == DRGN_OBJECT_ENCODING_SIGNED) {
Dwarf_Sword svalue;
if (dwarf_formsdata(attr, &svalue)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"invalid DW_AT_const_value");
}
return drgn_object_set_signed_internal(ret, &type, bit_size,
svalue);
} else if (encoding == DRGN_OBJECT_ENCODING_UNSIGNED) {
Dwarf_Word uvalue;
if (dwarf_formudata(attr, &uvalue)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"invalid DW_AT_const_value");
}
return drgn_object_set_unsigned_internal(ret, &type, bit_size,
uvalue);
} else {
return drgn_error_create(DRGN_ERROR_OTHER,
"unknown DW_AT_const_value form");
}
}
static struct drgn_error *
drgn_object_from_dwarf_variable(struct drgn_debug_info *dbinfo, Dwarf_Die *die,
uint64_t bias, const char *name,
struct drgn_object *ret)
{
struct drgn_qualified_type qualified_type;
struct drgn_error *err = drgn_type_from_dwarf_child(dbinfo, die, NULL,
true, true, NULL,
&qualified_type);
if (err)
return err;
Dwarf_Attribute attr_mem, *attr;
if ((attr = dwarf_attr_integrate(die, DW_AT_location, &attr_mem))) {
Dwarf_Op *loc;
size_t nloc;
if (dwarf_getlocation(attr, &loc, &nloc))
return drgn_error_libdw();
if (nloc != 1 || loc[0].atom != DW_OP_addr) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_AT_location has unimplemented operation");
}
enum drgn_byte_order byte_order;
err = dwarf_die_byte_order(die, true, &byte_order);
if (err)
return err;
return drgn_object_set_reference(ret, qualified_type,
loc[0].number + bias, 0, 0,
byte_order);
} else if ((attr = dwarf_attr_integrate(die, DW_AT_const_value,
&attr_mem))) {
return drgn_object_from_dwarf_constant(dbinfo, die,
qualified_type, attr,
ret);
} else {
return drgn_object_set_unavailable(ret, qualified_type, 0);
}
}
struct drgn_error *
drgn_debug_info_find_object(const char *name, size_t name_len,
const char *filename,
enum drgn_find_object_flags flags, void *arg,
struct drgn_object *ret)
{
struct drgn_error *err;
struct drgn_debug_info *dbinfo = arg;
struct drgn_dwarf_index_namespace *ns = &dbinfo->dindex.global;
if (name_len >= 2 && memcmp(name, "::", 2) == 0) {
/* Explicit global namespace. */
name_len -= 2;
name += 2;
}
const char *colons;
while ((colons = memmem(name, name_len, "::", 2))) {
struct drgn_dwarf_index_iterator it;
uint64_t ns_tag = DW_TAG_namespace;
err = drgn_dwarf_index_iterator_init(&it, ns, name,
colons - name, &ns_tag, 1);
if (err)
return err;
struct drgn_dwarf_index_die *index_die =
drgn_dwarf_index_iterator_next(&it);
if (!index_die)
return &drgn_not_found;
ns = index_die->namespace;
name_len -= colons + 2 - name;
name = colons + 2;
}
uint64_t tags[3];
size_t num_tags = 0;
if (flags & DRGN_FIND_OBJECT_CONSTANT)
tags[num_tags++] = DW_TAG_enumerator;
if (flags & DRGN_FIND_OBJECT_FUNCTION)
tags[num_tags++] = DW_TAG_subprogram;
if (flags & DRGN_FIND_OBJECT_VARIABLE)
tags[num_tags++] = DW_TAG_variable;
struct drgn_dwarf_index_iterator it;
err = drgn_dwarf_index_iterator_init(&it, ns, name, strlen(name), tags,
num_tags);
if (err)
return err;
struct drgn_dwarf_index_die *index_die;
while ((index_die = drgn_dwarf_index_iterator_next(&it))) {
Dwarf_Die die;
uint64_t bias;
err = drgn_dwarf_index_get_die(index_die, &die, &bias);
if (err)
return err;
if (!die_matches_filename(&die, filename))
continue;
switch (dwarf_tag(&die)) {
case DW_TAG_enumeration_type:
return drgn_object_from_dwarf_enumerator(dbinfo, &die,
name, ret);
case DW_TAG_subprogram:
return drgn_object_from_dwarf_subprogram(dbinfo, &die,
bias, name,
ret);
case DW_TAG_variable:
return drgn_object_from_dwarf_variable(dbinfo, &die,
bias, name, ret);
default:
UNREACHABLE();
}
}
return &drgn_not_found;
}
struct drgn_error *drgn_debug_info_create(struct drgn_program *prog,
struct drgn_debug_info **ret)
{
struct drgn_debug_info *dbinfo = malloc(sizeof(*dbinfo));
if (!dbinfo)
return &drgn_enomem;
dbinfo->prog = prog;
const Dwfl_Callbacks *dwfl_callbacks;
if (prog->flags & DRGN_PROGRAM_IS_LINUX_KERNEL)
dwfl_callbacks = &drgn_dwfl_callbacks;
else if (prog->flags & DRGN_PROGRAM_IS_LIVE)
dwfl_callbacks = &drgn_linux_proc_dwfl_callbacks;
else
dwfl_callbacks = &drgn_userspace_core_dump_dwfl_callbacks;
dbinfo->dwfl = dwfl_begin(dwfl_callbacks);
if (!dbinfo->dwfl) {
free(dbinfo);
return drgn_error_libdwfl();
}
drgn_debug_info_module_table_init(&dbinfo->modules);
c_string_set_init(&dbinfo->module_names);
drgn_dwarf_index_init(&dbinfo->dindex);
drgn_dwarf_type_map_init(&dbinfo->types);
drgn_dwarf_type_map_init(&dbinfo->cant_be_incomplete_array_types);
dbinfo->depth = 0;
*ret = dbinfo;
return NULL;
}
void drgn_debug_info_destroy(struct drgn_debug_info *dbinfo)
{
if (!dbinfo)
return;
drgn_dwarf_type_map_deinit(&dbinfo->cant_be_incomplete_array_types);
drgn_dwarf_type_map_deinit(&dbinfo->types);
drgn_dwarf_index_deinit(&dbinfo->dindex);
c_string_set_deinit(&dbinfo->module_names);
drgn_debug_info_free_modules(dbinfo, false, true);
assert(drgn_debug_info_module_table_empty(&dbinfo->modules));
drgn_debug_info_module_table_deinit(&dbinfo->modules);
dwfl_end(dbinfo->dwfl);
free(dbinfo);
}
struct drgn_error *open_elf_file(const char *path, int *fd_ret, Elf **elf_ret)
{
struct drgn_error *err;
*fd_ret = open(path, O_RDONLY);
if (*fd_ret == -1)
return drgn_error_create_os("open", errno, path);
*elf_ret = dwelf_elf_begin(*fd_ret);
if (!*elf_ret) {
err = drgn_error_libelf();
goto err_fd;
}
if (elf_kind(*elf_ret) != ELF_K_ELF) {
err = drgn_error_create(DRGN_ERROR_OTHER, "not an ELF file");
goto err_elf;
}
return NULL;
err_elf:
elf_end(*elf_ret);
err_fd:
close(*fd_ret);
return err;
}
struct drgn_error *find_elf_file(char **path_ret, int *fd_ret, Elf **elf_ret,
const char * const *path_formats, ...)
{
struct drgn_error *err;
size_t i;
for (i = 0; path_formats[i]; i++) {
va_list ap;
int ret;
char *path;
int fd;
Elf *elf;
va_start(ap, path_formats);
ret = vasprintf(&path, path_formats[i], ap);
va_end(ap);
if (ret == -1)
return &drgn_enomem;
fd = open(path, O_RDONLY);
if (fd == -1) {
free(path);
continue;
}
elf = dwelf_elf_begin(fd);
if (!elf) {
close(fd);
free(path);
continue;
}
if (elf_kind(elf) != ELF_K_ELF) {
err = drgn_error_format(DRGN_ERROR_OTHER,
"%s: not an ELF file", path);
elf_end(elf);
close(fd);
free(path);
return err;
}
*path_ret = path;
*fd_ret = fd;
*elf_ret = elf;
return NULL;
}
*path_ret = NULL;
*fd_ret = -1;
*elf_ret = NULL;
return NULL;
}
struct drgn_error *read_elf_section(Elf_Scn *scn, Elf_Data **ret)
{
GElf_Shdr shdr_mem, *shdr;
Elf_Data *data;
shdr = gelf_getshdr(scn, &shdr_mem);
if (!shdr)
return drgn_error_libelf();
if ((shdr->sh_flags & SHF_COMPRESSED) && elf_compress(scn, 0, 0) < 0)
return drgn_error_libelf();
data = elf_getdata(scn, NULL);
if (!data)
return drgn_error_libelf();
*ret = data;
return NULL;
}
struct drgn_error *elf_address_range(Elf *elf, uint64_t bias,
uint64_t *start_ret, uint64_t *end_ret)
{
uint64_t start = UINT64_MAX, end = 0;
size_t phnum, i;
/*
* Get the minimum and maximum addresses from the PT_LOAD segments. We
* ignore memory ranges that start beyond UINT64_MAX, and we truncate
* ranges that end beyond UINT64_MAX.
*/
if (elf_getphdrnum(elf, &phnum) != 0)
return drgn_error_libelf();
for (i = 0; i < phnum; i++) {
GElf_Phdr phdr_mem, *phdr;
uint64_t segment_start, segment_end;
phdr = gelf_getphdr(elf, i, &phdr_mem);
if (!phdr)
return drgn_error_libelf();
if (phdr->p_type != PT_LOAD || !phdr->p_vaddr)
continue;
if (__builtin_add_overflow(phdr->p_vaddr, bias,
&segment_start))
continue;
if (__builtin_add_overflow(segment_start, phdr->p_memsz,
&segment_end))
segment_end = UINT64_MAX;
if (segment_start < segment_end) {
if (segment_start < start)
start = segment_start;
if (segment_end > end)
end = segment_end;
}
}
if (start >= end) {
return drgn_error_create(DRGN_ERROR_OTHER,
"ELF file has no loadable segments");
}
*start_ret = start;
*end_ret = end;
return NULL;
}
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