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drgn/libdrgn/linux_kernel.h

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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
// Copyright 2018-2019 - Omar Sandoval
// SPDX-License-Identifier: GPL-3.0+
#ifndef DRGN_LINUX_KERNEL_H
#define DRGN_LINUX_KERNEL_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 <elfutils/libdwfl.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 "drgn.h"
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 drgn_dwarf_index;
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_memory_reader;
struct vmcoreinfo;
struct drgn_error *parse_vmcoreinfo(const char *desc, size_t descsz,
struct vmcoreinfo *ret);
struct drgn_error *read_vmcoreinfo_fallback(struct drgn_memory_reader *reader,
bool have_non_zero_phys_addr,
struct vmcoreinfo *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 *
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
linux_kernel_report_debug_info(struct drgn_program *prog,
struct drgn_dwarf_index *dindex,
const char **paths, size_t n,
libdrgn: support loading only load main debug info If we only want debugging information for vmlinux and not kernel modules, it'd be nice to only load the former. This adds a load_main parameter to drgn_program_load_debug_info() which specifies just that. For now, it's only implemented for the Linux kernel. While we're here, let's make the paths parameter optional for the Python bindings.
2019-11-23 00:21:36 +00:00
bool report_default, bool report_main);
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
Add support for kdump-compressed core dumps with libkdumpfile
2019-08-02 08:00:59 +01:00
#define KDUMP_SIGNATURE "KDUMP "
#define KDUMP_SIG_LEN (sizeof(KDUMP_SIGNATURE) - 1)
#ifdef WITH_LIBKDUMPFILE
struct drgn_error *drgn_program_set_kdump(struct drgn_program *prog);
#else
static inline struct drgn_error *
drgn_program_set_kdump(struct drgn_program *prog)
{
return drgn_error_create(DRGN_ERROR_INVALID_ARGUMENT,
"drgn was built without libkdumpfile support");
}
#endif
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
#endif /* DRGN_LINUX_KERNEL_H */
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