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e5874ad18a
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.
105 lines
2.7 KiB
C
105 lines
2.7 KiB
C
// Copyright 2018-2019 - Omar Sandoval
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// SPDX-License-Identifier: GPL-3.0+
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/**
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* @file
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*
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* Debugging information cache.
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*
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* See @ref DWARFInfoCache.
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*/
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#ifndef DRGN_DWARF_INFO_CACHE_H
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#define DRGN_DWARF_INFO_CACHE_H
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#include "drgn.h"
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#include "hash_table.h"
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/**
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* @ingroup Internals
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*
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* @defgroup DWARFInfoCache Debugging information cache
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*
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* Caching of DWARF debugging information.
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*
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* @ref drgn_dwarf_info_cache bridges the raw DWARF information indexed by @ref
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* drgn_dwarf_index to the higher-level @ref drgn_type_index and @ref
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* drgn_symbol_index.
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*
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* @{
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*/
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/** Cached type in a @ref drgn_dwarf_info_cache. */
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struct drgn_dwarf_type {
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struct drgn_type *type;
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enum drgn_qualifiers qualifiers;
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/**
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* Whether this is an incomplete array type or a typedef of one.
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*
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* This is used to work around a GCC bug; see @ref
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* drgn_type_from_dwarf_internal().
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*/
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bool is_incomplete_array;
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/** Whether we need to free @c type. */
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bool should_free;
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};
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DEFINE_HASH_MAP_TYPE(dwarf_type_map, const void *, struct drgn_dwarf_type);
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struct drgn_dwarf_index;
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struct drgn_program;
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struct drgn_symbol;
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/**
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* Cache of types and symbols from DWARF debugging information.
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*
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* This is the argument for @ref drgn_dwarf_type_find() and @ref
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* drgn_dwarf_symbol_find().
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*/
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struct drgn_dwarf_info_cache {
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/** Index of DWARF debugging information. */
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struct drgn_dwarf_index dindex;
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/**
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* Cache of parsed types.
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*
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* The key is the address of the DIE (@c Dwarf_Die::addr). The value is
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* a @ref drgn_dwarf_type.
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*/
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struct dwarf_type_map map;
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/**
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* Cache of parsed types which appear to be incomplete array types but
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* can't be.
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*
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* See @ref drgn_type_from_dwarf_internal().
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*/
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struct dwarf_type_map cant_be_incomplete_array_map;
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/** Current parsing recursion depth. */
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int depth;
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/** Type index. */
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struct drgn_type_index *tindex;
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};
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/** Create a @ref drgn_dwarf_info_cache. */
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struct drgn_error *
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drgn_dwarf_info_cache_create(struct drgn_type_index *tindex,
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struct drgn_dwarf_info_cache **ret);
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/** Destroy a @ref drgn_dwarf_info_cache. */
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void drgn_dwarf_info_cache_destroy(struct drgn_dwarf_info_cache *dicache);
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/** @ref drgn_type_find_fn() that uses DWARF debugging information. */
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struct drgn_error *drgn_dwarf_type_find(enum drgn_type_kind kind,
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const char *name, size_t name_len,
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const char *filename, void *arg,
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struct drgn_qualified_type *ret);
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/** @ref drgn_symbol_find_fn() that uses DWARF debugging information. */
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struct drgn_error *
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drgn_dwarf_symbol_find(const char *name, size_t name_len, const char *filename,
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enum drgn_find_object_flags flags, void *arg,
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struct drgn_symbol *ret);
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/** @} */
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#endif /* DRGN_DWARF_INFO_CACHE_H */
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