drgn/libdrgn/linux_kernel.h
Omar Sandoval e5874ad18a 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 12:27:48 -07:00

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C

// Copyright 2018-2019 - Omar Sandoval
// SPDX-License-Identifier: GPL-3.0+
#ifndef DRGN_LINUX_KERNEL_H
#define DRGN_LINUX_KERNEL_H
#include <elfutils/libdwfl.h>
#include "drgn.h"
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);
struct drgn_error *
linux_kernel_load_debug_info(struct drgn_program *prog, const char **paths,
size_t n);
struct drgn_error *
linux_kernel_load_default_debug_info(struct drgn_program *prog);
#endif /* DRGN_LINUX_KERNEL_H */