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e105be6c18
drgn/libdrgn/debug_info.c
Omar Sandoval e105be6c18 libdrgn: debug_info: add helper to cache module section 
Signed-off-by: Omar Sandoval <osandov@osandov.com>
2021-06-05 16:18:51 -07:00

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132 KiB
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// Copyright (c) Facebook, Inc. and its affiliates.
// SPDX-License-Identifier: GPL-3.0-or-later
#include <assert.h>
#include <byteswap.h>
#include <dwarf.h>
#include <elf.h>
#include <elfutils/known-dwarf.h>
#include <elfutils/libdw.h>
#include <elfutils/libdwelf.h>
#include <elfutils/version.h>
#include <errno.h>
#include <fcntl.h>
#include <gelf.h>
#include <inttypes.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "debug_info.h"
#include "error.h"
#include "language.h"
#include "lazy_object.h"
#include "linux_kernel.h"
#include "object.h"
#include "orc.h"
#include "path.h"
#include "program.h"
#include "register_state.h"
#include "serialize.h"
#include "type.h"
#include "util.h"
struct drgn_dwarf_cie {
/* Whether this CIE is from .eh_frame. */
bool is_eh;
/* Size of an address in this CIE in bytes. */
uint8_t address_size;
/* DW_EH_PE_* encoding of addresses in this CIE. */
uint8_t address_encoding;
/* Whether this CIE has a 'z' augmentation. */
bool have_augmentation_length;
/* Whether this CIE is for a signal handler ('S' augmentation). */
bool signal_frame;
drgn_register_number return_address_register;
uint64_t code_alignment_factor;
int64_t data_alignment_factor;
const char *initial_instructions;
size_t initial_instructions_size;
};
struct drgn_dwarf_fde {
uint64_t initial_location;
uint64_t address_range;
/* CIE for this FDE as an index into drgn_debug_info_module::cies. */
size_t cie;
const char *instructions;
size_t instructions_size;
};
DEFINE_VECTOR(drgn_dwarf_fde_vector, struct drgn_dwarf_fde)
DEFINE_VECTOR(drgn_dwarf_cie_vector, struct drgn_dwarf_cie)
DEFINE_HASH_MAP(drgn_dwarf_cie_map, size_t, size_t, int_key_hash_pair,
scalar_key_eq)
DEFINE_VECTOR(drgn_cfi_row_vector, struct drgn_cfi_row *)
DEFINE_VECTOR(uint64_vector, uint64_t)
#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_TYPES] = ".debug_types",
[DRGN_SCN_DEBUG_ABBREV] = ".debug_abbrev",
[DRGN_SCN_DEBUG_STR] = ".debug_str",
[DRGN_SCN_DEBUG_LINE] = ".debug_line",
[DRGN_SCN_DEBUG_FRAME] = ".debug_frame",
[DRGN_SCN_EH_FRAME] = ".eh_frame",
[DRGN_SCN_ORC_UNWIND_IP] = ".orc_unwind_ip",
[DRGN_SCN_ORC_UNWIND] = ".orc_unwind",
[DRGN_SCN_TEXT] = ".text",
[DRGN_SCN_GOT] = ".got",
};
struct drgn_error *
drgn_error_debug_info_scn(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->scn_data[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_scn(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);
free(module->orc_entries);
free(module->orc_pc_offsets);
free(module->fdes);
free(module->cies);
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 = calloc(1, 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;
}
}
module->dwfl_module = dwfl_module;
module->path = path_key;
module->fd = fd;
module->elf = elf;
/* 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 *relocate_elf_section(Elf_Scn *scn, Elf_Scn *reloc_scn,
Elf_Scn *symtab_scn,
const uint64_t *sh_addrs,
size_t shdrnum,
const struct drgn_platform *platform)
{
struct drgn_error *err;
bool is_64_bit = drgn_platform_is_64_bit(platform);
bool bswap = drgn_platform_bswap(platform);
apply_elf_rela_fn *apply_elf_rela = platform->arch->apply_elf_rela;
Elf_Data *data, *reloc_data, *symtab_data;
err = read_elf_section(scn, &data);
if (err)
return err;
struct drgn_relocating_section relocating = {
.buf = data->d_buf,
.buf_size = data->d_size,
.addr = sh_addrs[elf_ndxscn(scn)],
.bswap = bswap,
};
err = read_elf_section(reloc_scn, &reloc_data);
if (err)
return err;
const void *relocs = reloc_data->d_buf;
size_t reloc_size = is_64_bit ? sizeof(Elf64_Rela) : sizeof(Elf32_Rela);
size_t num_relocs = reloc_data->d_size / reloc_size;
err = read_elf_section(symtab_scn, &symtab_data);
if (err)
return err;
const void *syms = symtab_data->d_buf;
size_t sym_size = is_64_bit ? sizeof(Elf64_Sym) : sizeof(Elf32_Sym);
size_t num_syms = symtab_data->d_size / sym_size;
for (size_t i = 0; i < num_relocs; i++) {
uint64_t r_offset;
uint32_t r_sym;
uint32_t r_type;
int64_t r_addend;
if (is_64_bit) {
Elf64_Rela *rela = (Elf64_Rela *)relocs + i;
uint64_t r_info;
memcpy(&r_offset, &rela->r_offset, sizeof(r_offset));
memcpy(&r_info, &rela->r_info, sizeof(r_info));
memcpy(&r_addend, &rela->r_addend, sizeof(r_addend));
if (bswap) {
r_offset = bswap_64(r_offset);
r_info = bswap_64(r_info);
r_addend = bswap_64(r_addend);
}
r_sym = ELF64_R_SYM(r_info);
r_type = ELF64_R_TYPE(r_info);
} else {
Elf32_Rela *rela32 = (Elf32_Rela *)relocs + i;
uint32_t r_offset32;
uint32_t r_info32;
int32_t r_addend32;
memcpy(&r_offset32, &rela32->r_offset, sizeof(r_offset32));
memcpy(&r_info32, &rela32->r_info, sizeof(r_info32));
memcpy(&r_addend32, &rela32->r_addend, sizeof(r_addend32));
if (bswap) {
r_offset32 = bswap_32(r_offset32);
r_info32 = bswap_32(r_info32);
r_addend32 = bswap_32(r_addend32);
}
r_offset = r_offset32;
r_sym = ELF32_R_SYM(r_info32);
r_type = ELF32_R_TYPE(r_info32);
r_addend = r_addend32;
}
if (r_sym >= num_syms) {
return drgn_error_create(DRGN_ERROR_OTHER,
"invalid ELF relocation symbol");
}
uint16_t st_shndx;
uint64_t st_value;
if (is_64_bit) {
const Elf64_Sym *sym = (Elf64_Sym *)syms + r_sym;
memcpy(&st_shndx, &sym->st_shndx, sizeof(st_shndx));
memcpy(&st_value, &sym->st_value, sizeof(st_value));
if (bswap) {
st_shndx = bswap_16(st_shndx);
st_value = bswap_64(st_value);
}
} else {
const Elf32_Sym *sym = (Elf32_Sym *)syms + r_sym;
memcpy(&st_shndx, &sym->st_shndx, sizeof(st_shndx));
uint32_t st_value32;
memcpy(&st_value32, &sym->st_value, sizeof(st_value32));
if (bswap) {
st_shndx = bswap_16(st_shndx);
st_value32 = bswap_32(st_value32);
}
st_value = st_value32;
}
if (st_shndx >= shdrnum) {
return drgn_error_create(DRGN_ERROR_OTHER,
"invalid ELF symbol section index");
}
err = apply_elf_rela(&relocating, r_offset, r_type, r_addend,
sh_addrs[st_shndx] + st_value);
if (err)
return err;
}
/*
* Mark the relocation section as empty so that libdwfl doesn't try to
* apply it again.
*/
GElf_Shdr *shdr, shdr_mem;
shdr = gelf_getshdr(reloc_scn, &shdr_mem);
if (!shdr)
return drgn_error_libelf();
shdr->sh_size = 0;
if (!gelf_update_shdr(reloc_scn, shdr))
return drgn_error_libelf();
reloc_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.
*/
static struct drgn_error *relocate_elf_file(Elf *elf)
{
struct drgn_error *err;
GElf_Ehdr ehdr_mem, *ehdr;
ehdr = gelf_getehdr(elf, &ehdr_mem);
if (!ehdr)
return drgn_error_libelf();
if (ehdr->e_type != ET_REL) {
/* Not a relocatable file. */
return NULL;
}
struct drgn_platform platform;
drgn_platform_from_elf(ehdr, &platform);
if (!platform.arch->apply_elf_rela) {
/* Unsupported; fall back to libdwfl. */
return NULL;
}
size_t shdrnum;
if (elf_getshdrnum(elf, &shdrnum))
return drgn_error_libelf();
uint64_t *sh_addrs = calloc(shdrnum, sizeof(sh_addrs[0]));
if (!sh_addrs && shdrnum > 0)
return &drgn_enomem;
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn(elf, scn))) {
GElf_Shdr *shdr, shdr_mem;
shdr = gelf_getshdr(scn, &shdr_mem);
if (!shdr) {
err = drgn_error_libelf();
goto out;
}
sh_addrs[elf_ndxscn(scn)] = shdr->sh_addr;
}
size_t shstrndx;
if (elf_getshdrstrndx(elf, &shstrndx)) {
err = drgn_error_libelf();
goto out;
}
Elf_Scn *reloc_scn = NULL;
while ((reloc_scn = elf_nextscn(elf, reloc_scn))) {
GElf_Shdr *shdr, shdr_mem;
shdr = gelf_getshdr(reloc_scn, &shdr_mem);
if (!shdr) {
err = drgn_error_libelf();
goto out;
}
/* We don't support any architectures that use SHT_REL yet. */
if (shdr->sh_type != SHT_RELA)
continue;
const char *scnname = elf_strptr(elf, shstrndx, shdr->sh_name);
if (!scnname) {
err = drgn_error_libelf();
goto out;
}
if (strstartswith(scnname, ".rela.debug_") ||
strstartswith(scnname, ".rela.orc_")) {
Elf_Scn *scn = elf_getscn(elf, shdr->sh_info);
if (!scn) {
err = drgn_error_libelf();
goto out;
}
Elf_Scn *symtab_scn = elf_getscn(elf, shdr->sh_link);
if (!symtab_scn) {
err = drgn_error_libelf();
goto out;
}
err = relocate_elf_section(scn, reloc_scn, symtab_scn,
sh_addrs, shdrnum,
&platform);
if (err)
goto out;
}
}
out:
free(sh_addrs);
return NULL;
}
static struct drgn_error *
drgn_debug_info_find_sections(struct drgn_debug_info_module *module)
{
struct drgn_error *err;
if (module->elf) {
err = relocate_elf_file(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();
GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr(elf, &ehdr_mem);
if (!ehdr)
return drgn_error_libelf();
drgn_platform_from_elf(ehdr, &module->platform);
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_PROGBITS)
continue;
const char *scnname = elf_strptr(elf, shstrndx, shdr->sh_name);
if (!scnname)
return drgn_error_libelf();
for (size_t i = 0; i < DRGN_NUM_DEBUG_SCNS; i++) {
if (!module->scns[i] &&
strcmp(scnname, drgn_debug_scn_names[i]) == 0) {
module->scns[i] = scn;
break;
}
}
}
return NULL;
}
static struct drgn_error *
drgn_debug_info_precache_sections(struct drgn_debug_info_module *module)
{
struct drgn_error *err;
for (size_t i = 0; i < DRGN_NUM_DEBUG_SCN_DATA_PRECACHE; i++) {
if (module->scns[i]) {
err = read_elf_section(module->scns[i],
&module->scn_data[i]);
if (err)
return err;
}
}
/*
* Truncate any extraneous bytes so that we can assume that a pointer
* within .debug_str is always null-terminated.
*/
Elf_Data *debug_str = module->scn_data[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_module_cache_section(struct drgn_debug_info_module *module,
enum drgn_debug_info_scn scn)
{
if (module->scn_data[scn])
return NULL;
return read_elf_section(module->scns[scn], &module->scn_data[scn]);
}
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_debug_info_find_sections(module);
if (err) {
module->err = err;
continue;
}
if (module->scns[DRGN_SCN_DEBUG_INFO] &&
module->scns[DRGN_SCN_DEBUG_ABBREV]) {
err = drgn_debug_info_precache_sections(module);
if (err) {
module->err = err;
continue;
}
module->state = DRGN_DEBUG_INFO_MODULE_INDEXING;
return drgn_dwarf_index_read_module(dindex_state,
module);
}
}
/*
* 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;
if (!drgn_dwarf_index_update_state_init(&dindex_state, &dbinfo->dindex))
return &drgn_enomem;
struct drgn_error *err = NULL;
#pragma omp parallel for schedule(dynamic)
for (size_t i = 0; i < load->new_modules.size; i++) {
if (err)
continue;
struct drgn_error *module_err =
drgn_debug_info_read_module(load, &dindex_state,
load->new_modules.data[i]);
if (module_err) {
#pragma omp critical(drgn_debug_info_update_index_error)
if (err)
drgn_error_destroy(module_err);
else
err = module_err;
}
}
if (!err)
err = drgn_dwarf_index_update(&dindex_state);
drgn_dwarf_index_update_state_deinit(&dindex_state);
if (!err)
drgn_debug_info_free_modules(dbinfo, true, false);
return err;
}
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;
}
struct drgn_dwarf_expression_buffer {
struct binary_buffer bb;
const char *start;
struct drgn_debug_info_module *module;
};
static struct drgn_error *
drgn_error_debug_info(struct drgn_debug_info_module *module, const char *ptr,
const char *message)
{
uintptr_t p = (uintptr_t)ptr;
int end_match = -1;
for (int i = 0; i < ARRAY_SIZE(module->scn_data); i++) {
if (!module->scn_data[i])
continue;
uintptr_t start = (uintptr_t)module->scn_data[i]->d_buf;
uintptr_t end = start + module->scn_data[i]->d_size;
if (start <= p) {
if (p < end) {
return drgn_error_debug_info_scn(module, i, ptr,
message);
} else if (p == end) {
end_match = i;
}
}
}
if (end_match != -1) {
/*
* The pointer doesn't lie within a section, but it does point
* to the end of a section.
*/
return drgn_error_debug_info_scn(module, end_match, ptr,
message);
}
/* We couldn't find the section containing the pointer. */
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", name, message);
}
static struct drgn_error *
drgn_dwarf_expression_buffer_error(struct binary_buffer *bb, const char *pos,
const char *message)
{
struct drgn_dwarf_expression_buffer *buffer =
container_of(bb, struct drgn_dwarf_expression_buffer, bb);
return drgn_error_debug_info(buffer->module, pos, message);
}
static void
drgn_dwarf_expression_buffer_init(struct drgn_dwarf_expression_buffer *buffer,
struct drgn_debug_info_module *module,
const char *expr, size_t expr_size)
{
binary_buffer_init(&buffer->bb, expr, expr_size,
drgn_platform_is_little_endian(&module->platform),
drgn_dwarf_expression_buffer_error);
buffer->start = expr;
buffer->module = module;
}
/* Returns &drgn_not_found if it tried to use an unknown register value. */
static struct drgn_error *
drgn_eval_dwarf_expression(struct drgn_program *prog,
struct drgn_dwarf_expression_buffer *expr,
struct uint64_vector *stack,
const struct drgn_register_state *regs)
{
struct drgn_error *err;
const struct drgn_platform *platform = &expr->module->platform;
bool little_endian = drgn_platform_is_little_endian(platform);
uint8_t address_size = drgn_platform_address_size(platform);
uint8_t address_bits = address_size * CHAR_BIT;
uint64_t address_mask = uint_max(address_size);
drgn_register_number (*dwarf_regno_to_internal)(uint64_t) =
platform->arch->dwarf_regno_to_internal;
#define CHECK(n) do { \
size_t _n = (n); \
if (stack->size < _n) { \
return binary_buffer_error(&expr->bb, \
"DWARF expression stack underflow"); \
} \
} while (0)
#define ELEM(i) stack->data[stack->size - 1 - (i)]
#define PUSH(x) do { \
uint64_t push = (x); \
if (!uint64_vector_append(stack, &push)) \
return &drgn_enomem; \
} while (0)
#define PUSH_MASK(x) PUSH((x) & address_mask)
/* Arbitrary limit so we don't go into an infinite loop. */
int remaining_ops = 10000;
while (binary_buffer_has_next(&expr->bb)) {
if (remaining_ops <= 0) {
return binary_buffer_error(&expr->bb,
"DWARF expression executed too many operations");
}
remaining_ops--;
uint8_t opcode;
if ((err = binary_buffer_next_u8(&expr->bb, &opcode)))
return err;
uint64_t uvalue;
uint64_t dwarf_regno;
uint8_t deref_size;
switch (opcode) {
/* Literal encodings. */
case DW_OP_lit0 ... DW_OP_lit31:
PUSH(opcode - DW_OP_lit0);
break;
case DW_OP_addr:
if ((err = binary_buffer_next_uint(&expr->bb,
address_size,
&uvalue)))
return err;
PUSH(uvalue);
break;
case DW_OP_const1u:
if ((err = binary_buffer_next_u8_into_u64(&expr->bb,
&uvalue)))
return err;
PUSH(uvalue);
break;
case DW_OP_const2u:
if ((err = binary_buffer_next_u16_into_u64(&expr->bb,
&uvalue)))
return err;
PUSH_MASK(uvalue);
break;
case DW_OP_const4u:
if ((err = binary_buffer_next_u32_into_u64(&expr->bb,
&uvalue)))
return err;
PUSH_MASK(uvalue);
break;
case DW_OP_const8u:
if ((err = binary_buffer_next_u64(&expr->bb, &uvalue)))
return err;
PUSH_MASK(uvalue);
break;
case DW_OP_const1s:
if ((err = binary_buffer_next_s8_into_u64(&expr->bb,
&uvalue)))
return err;
PUSH_MASK(uvalue);
break;
case DW_OP_const2s:
if ((err = binary_buffer_next_s16_into_u64(&expr->bb,
&uvalue)))
return err;
PUSH_MASK(uvalue);
break;
case DW_OP_const4s:
if ((err = binary_buffer_next_s32_into_u64(&expr->bb,
&uvalue)))
return err;
PUSH_MASK(uvalue);
break;
case DW_OP_const8s:
if ((err = binary_buffer_next_s64_into_u64(&expr->bb,
&uvalue)))
return err;
PUSH_MASK(uvalue);
break;
case DW_OP_constu:
if ((err = binary_buffer_next_uleb128(&expr->bb,
&uvalue)))
return err;
PUSH_MASK(uvalue);
break;
case DW_OP_consts:
if ((err = binary_buffer_next_sleb128_into_u64(&expr->bb,
&uvalue)))
return err;
PUSH_MASK(uvalue);
break;
/* Register values. */
case DW_OP_breg0 ... DW_OP_breg31:
dwarf_regno = opcode - DW_OP_breg0;
goto breg;
case DW_OP_bregx:
if ((err = binary_buffer_next_uleb128(&expr->bb,
&dwarf_regno)))
return err;
breg:
{
if (!regs)
return &drgn_not_found;
drgn_register_number regno =
dwarf_regno_to_internal(dwarf_regno);
if (!drgn_register_state_has_register(regs, regno))
return &drgn_not_found;
const struct drgn_register_layout *layout =
&platform->arch->register_layout[regno];
copy_lsbytes(&uvalue, sizeof(uvalue),
HOST_LITTLE_ENDIAN,
&regs->buf[layout->offset], layout->size,
little_endian);
int64_t svalue;
if ((err = binary_buffer_next_sleb128(&expr->bb,
&svalue)))
return err;
PUSH_MASK(uvalue + svalue);
break;
}
/* Stack operations. */
case DW_OP_dup:
CHECK(1);
PUSH(ELEM(0));
break;
case DW_OP_drop:
CHECK(1);
stack->size--;
break;
case DW_OP_pick: {
uint8_t index;
if ((err = binary_buffer_next_u8(&expr->bb, &index)))
return err;
CHECK(index + 1);
PUSH(ELEM(index));
break;
}
case DW_OP_over:
CHECK(2);
PUSH(ELEM(1));
break;
case DW_OP_swap:
CHECK(2);
uvalue = ELEM(0);
ELEM(0) = ELEM(1);
ELEM(1) = uvalue;
break;
case DW_OP_rot:
CHECK(3);
uvalue = ELEM(0);
ELEM(0) = ELEM(1);
ELEM(1) = ELEM(2);
ELEM(2) = uvalue;
break;
case DW_OP_deref:
deref_size = address_size;
goto deref;
case DW_OP_deref_size:
if ((err = binary_buffer_next_u8(&expr->bb,
&deref_size)))
return err;
if (deref_size > address_size) {
return binary_buffer_error(&expr->bb,
"DW_OP_deref_size has invalid size");
}
deref:
{
CHECK(1);
char deref_buf[8];
err = drgn_program_read_memory(prog, deref_buf, ELEM(0),
deref_size, false);
if (err)
return err;
copy_lsbytes(&ELEM(0), sizeof(ELEM(0)),
HOST_LITTLE_ENDIAN, deref_buf, deref_size,
little_endian);
break;
}
case DW_OP_call_frame_cfa: {
if (!regs)
return &drgn_not_found;
/*
* The DWARF 5 specification says that
* DW_OP_call_frame_cfa cannot be used for CFI. For
* DW_CFA_def_cfa_expression, it is clearly invalid to
* define the CFA in terms of the CFA, and it will fail
* naturally below. This restriction doesn't make sense
* for DW_CFA_expression and DW_CFA_val_expression, as
* they push the CFA and thus depend on it anyways, so
* we don't bother enforcing it.
*/
struct optional_uint64 cfa =
drgn_register_state_get_cfa(regs);
if (!cfa.has_value)
return &drgn_not_found;
PUSH(cfa.value);
break;
}
/* Arithmetic and logical operations. */
#define UNOP_MASK(op) do { \
CHECK(1); \
ELEM(0) = (op ELEM(0)) & address_mask; \
} while (0)
#define BINOP(op) do { \
CHECK(2); \
ELEM(1) = ELEM(1) op ELEM(0); \
stack->size--; \
} while (0)
#define BINOP_MASK(op) do { \
CHECK(2); \
ELEM(1) = (ELEM(1) op ELEM(0)) & address_mask; \
stack->size--; \
} while (0)
case DW_OP_abs:
CHECK(1);
if (ELEM(0) & (UINT64_C(1) << (address_bits - 1)))
ELEM(0) = -ELEM(0) & address_mask;
break;
case DW_OP_and:
BINOP(&);
break;
case DW_OP_div:
CHECK(2);
if (ELEM(0) == 0) {
return binary_buffer_error(&expr->bb,
"division by zero in DWARF expression");
}
ELEM(1) = ((truncate_signed(ELEM(1), address_bits)
/ truncate_signed(ELEM(0), address_bits))
& address_mask);
stack->size--;
break;
case DW_OP_minus:
BINOP_MASK(-);
break;
case DW_OP_mod:
CHECK(2);
if (ELEM(0) == 0) {
return binary_buffer_error(&expr->bb,
"modulo by zero in DWARF expression");
}
ELEM(1) = ELEM(1) % ELEM(0);
stack->size--;
break;
case DW_OP_mul:
BINOP_MASK(*);
break;
case DW_OP_neg:
UNOP_MASK(-);
break;
case DW_OP_not:
UNOP_MASK(~);
break;
case DW_OP_or:
BINOP(|);
break;
case DW_OP_plus:
BINOP_MASK(+);
break;
case DW_OP_plus_uconst:
CHECK(1);
if ((err = binary_buffer_next_uleb128(&expr->bb,
&uvalue)))
return err;
ELEM(0) = (ELEM(0) + uvalue) & address_mask;
break;
case DW_OP_shl:
CHECK(2);
if (ELEM(0) < address_bits)
ELEM(1) = (ELEM(1) << ELEM(0)) & address_mask;
else
ELEM(1) = 0;
stack->size--;
break;
case DW_OP_shr:
CHECK(2);
if (ELEM(0) < address_bits)
ELEM(1) >>= ELEM(0);
else
ELEM(1) = 0;
stack->size--;
break;
case DW_OP_shra:
CHECK(2);
if (ELEM(0) < address_bits) {
ELEM(1) = ((truncate_signed(ELEM(1), address_bits)
>> ELEM(0))
& address_mask);
} else if (ELEM(1) & (UINT64_C(1) << (address_bits - 1))) {
ELEM(1) = -INT64_C(1) & address_mask;
} else {
ELEM(1) = 0;
}
stack->size--;
break;
case DW_OP_xor:
BINOP(^);
break;
#undef BINOP_MASK
#undef BINOP
#undef UNOP_MASK
/* Control flow operations. */
#define RELOP(op) do { \
CHECK(2); \
ELEM(1) = (truncate_signed(ELEM(1), address_bits) op \
truncate_signed(ELEM(0), address_bits)); \
stack->size--; \
} while (0)
case DW_OP_le:
RELOP(<=);
break;
case DW_OP_ge:
RELOP(>=);
break;
case DW_OP_eq:
RELOP(==);
break;
case DW_OP_lt:
RELOP(<);
break;
case DW_OP_gt:
RELOP(>);
break;
case DW_OP_ne:
RELOP(!=);
break;
#undef RELOP
case DW_OP_skip:
branch:
{
int16_t skip;
if ((err = binary_buffer_next_s16(&expr->bb, &skip)))
return err;
if ((skip >= 0 && skip > expr->bb.end - expr->bb.pos) ||
(skip < 0 && -skip > expr->bb.pos - expr->start)) {
return binary_buffer_error(&expr->bb,
"DWARF expression branch is out of bounds");
}
expr->bb.pos += skip;
break;
}
case DW_OP_bra:
CHECK(1);
if (ELEM(0)) {
stack->size--;
goto branch;
} else {
stack->size--;
if ((err = binary_buffer_skip(&expr->bb, 2)))
return err;
}
break;
/* Special operations. */
case DW_OP_nop:
break;
/*
* We don't yet support:
*
* - DW_OP_fbreg
* - DW_OP_push_object_address
* - DW_OP_form_tls_address
* - DW_OP_entry_value
* - Procedure calls: DW_OP_call2, DW_OP_call4, DW_OP_call_ref.
* - Location description operations: DW_OP_reg0-DW_OP_reg31,
* DW_OP_regx, DW_OP_implicit_value, DW_OP_stack_value,
* DW_OP_implicit_pointer, DW_OP_piece, DW_OP_bit_piece.
* - Operations that use .debug_addr: DW_OP_addrx,
* DW_OP_constx.
* - Typed operations: DW_OP_const_type, DW_OP_regval_type,
* DW_OP_deref_type, DW_OP_convert, DW_OP_reinterpret.
* - Operations for multiple address spaces: DW_OP_xderef,
* DW_OP_xderef_size, DW_OP_xderef_type.
*/
default:
return binary_buffer_error(&expr->bb,
"unknown DWARF expression opcode %#" PRIx8,
opcode);
}
}
#undef PUSH_MASK
#undef PUSH
#undef ELEM
#undef CHECK
return NULL;
}
DEFINE_HASH_TABLE_FUNCTIONS(drgn_dwarf_type_map, ptr_key_hash_pair,
scalar_key_eq)
/**
* 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 = drgn_byte_order_from_little_endian(little_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(die, name, &attr_mem))) {
*ret = false;
return 0;
}
return dwarf_formflag(attr, ret);
}
static int dwarf_flag_integrate(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] module Module containing @p die.
* @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,
struct drgn_debug_info_module *module,
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] module Module containing @p die.
* @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,
struct drgn_debug_info_module *module, Dwarf_Die *die,
struct drgn_qualified_type *ret)
{
return drgn_type_from_dwarf_internal(dbinfo, module, die, true, NULL,
ret);
}
/**
* Parse a type from the @c DW_AT_type attribute of a DWARF debugging
* information entry.
*
* @param[in] dbinfo Debugging information.
* @param[in] module Module containing @p die.
* @param[in] die DIE with @c DW_AT_type attribute.
* @param[in] lang Language of @p die if it is already known, @c NULL if it
* should be determined from @p 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_attr(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module, Dwarf_Die *die,
const struct drgn_language *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(die, DW_AT_type, &attr_mem))) {
if (can_be_void) {
if (!lang) {
err = drgn_language_from_die(die, true, &lang);
if (err)
return err;
}
ret->type = drgn_void_type(dbinfo->prog, lang);
ret->qualifiers = 0;
return NULL;
} else {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s is missing DW_AT_type",
dwarf_tag_str(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(die, tag_buf));
}
return drgn_type_from_dwarf_internal(dbinfo, module, &type_die,
can_be_incomplete_array,
is_incomplete_array_ret, ret);
}
static struct drgn_error *
drgn_object_from_dwarf_enumerator(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module,
Dwarf_Die *die, const char *name,
struct drgn_object *ret)
{
struct drgn_error *err;
struct drgn_qualified_type qualified_type;
err = drgn_type_from_dwarf(dbinfo, module, die, &qualified_type);
if (err)
return err;
const struct drgn_type_enumerator *enumerators =
drgn_type_enumerators(qualified_type.type);
size_t num_enumerators = drgn_type_num_enumerators(qualified_type.type);
for (size_t 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,
struct drgn_debug_info_module *module,
Dwarf_Die *die, struct drgn_object *ret)
{
struct drgn_qualified_type qualified_type;
struct drgn_error *err = drgn_type_from_dwarf(dbinfo, module, die,
&qualified_type);
if (err)
return err;
Dwarf_Addr low_pc;
if (dwarf_lowpc(die, &low_pc) == -1)
return drgn_object_set_absent(ret, qualified_type, 0);
Dwarf_Addr bias;
dwfl_module_info(module->dwfl_module, NULL, NULL, NULL, &bias, NULL,
NULL, NULL);
return drgn_object_set_reference(ret, qualified_type, low_pc + bias, 0,
0);
}
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;
struct drgn_error *err = drgn_object_type(qualified_type, 0, &type);
if (err)
return err;
Dwarf_Block block;
if (dwarf_formblock(attr, &block) == 0) {
if (block.length < drgn_value_size(type.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,
block.data, 0);
} else if (type.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");
}
drgn_object_set_signed_internal(ret, &type, svalue);
return NULL;
} else if (type.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");
}
drgn_object_set_unsigned_internal(ret, &type, uvalue);
return NULL;
} 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,
struct drgn_debug_info_module *module,
Dwarf_Die *die, struct drgn_object *ret)
{
/*
* The DWARF 5 specifications mentions that data object entries can have
* DW_AT_endianity, but that doesn't seem to be used in practice. It
* would be inconvenient to support, so ignore it for now.
*/
struct drgn_qualified_type qualified_type;
struct drgn_error *err = drgn_type_from_dwarf_attr(dbinfo, module,
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");
}
uint64_t address = loc[0].number;
Dwarf_Addr start, end, bias;
dwfl_module_info(module->dwfl_module, NULL, &start, &end, &bias,
NULL, NULL, NULL);
/*
* If the address is not in the module's address range, then
* it's probably something special like a Linux per-CPU variable
* (which isn't actually a variable address but an offset).
* Don't apply the bias in that case.
*/
if (start <= address + bias && address + bias < end)
address += bias;
return drgn_object_set_reference(ret, qualified_type, address,
0, 0);
} 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 {
if (dwarf_tag(die) == DW_TAG_template_value_parameter) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_AT_template_value_parameter is missing value");
}
return drgn_object_set_absent(ret, qualified_type, 0);
}
}
static struct drgn_error *
drgn_base_type_from_dwarf(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module, Dwarf_Die *die,
const struct drgn_language *lang,
struct drgn_type **ret)
{
struct drgn_error *err;
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");
}
enum drgn_byte_order byte_order;
err = dwarf_die_byte_order(die, true, &byte_order);
if (err)
return err;
switch (encoding) {
case DW_ATE_boolean:
return drgn_bool_type_create(dbinfo->prog, name, size,
byte_order, lang, ret);
case DW_ATE_float:
return drgn_float_type_create(dbinfo->prog, name, size,
byte_order, lang, ret);
case DW_ATE_signed:
case DW_ATE_signed_char:
return drgn_int_type_create(dbinfo->prog, name, size, true,
byte_order, lang, ret);
case DW_ATE_unsigned:
case DW_ATE_unsigned_char:
return drgn_int_type_create(dbinfo->prog, name, size, false,
byte_order, lang, ret);
/* We don't support complex types yet. */
case DW_ATE_complex_float:
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 &drgn_not_found. 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_not_found;
/*
* 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_not_found;
Dwarf_Die die;
err = drgn_dwarf_index_get_die(index_die, &die);
if (err)
return err;
struct drgn_qualified_type qualified_type;
err = drgn_type_from_dwarf(dbinfo, index_die->module, &die,
&qualified_type);
if (err)
return err;
*ret = qualified_type.type;
return NULL;
}
struct drgn_dwarf_member_thunk_arg {
struct drgn_debug_info_module *module;
Dwarf_Die die;
bool can_be_incomplete_array;
};
static struct drgn_error *
drgn_dwarf_member_thunk_fn(struct drgn_object *res, void *arg_)
{
struct drgn_error *err;
struct drgn_dwarf_member_thunk_arg *arg = arg_;
if (res) {
struct drgn_qualified_type qualified_type;
err = drgn_type_from_dwarf_attr(drgn_object_program(res)->_dbinfo,
arg->module, &arg->die, NULL,
false,
arg->can_be_incomplete_array,
NULL, &qualified_type);
if (err)
return err;
Dwarf_Attribute attr_mem, *attr;
uint64_t bit_field_size;
if ((attr = dwarf_attr_integrate(&arg->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;
}
err = drgn_object_set_absent(res, qualified_type,
bit_field_size);
if (err)
return err;
}
free(arg);
return NULL;
}
static struct drgn_error *
parse_member_offset(Dwarf_Die *die, union drgn_lazy_object *member_object,
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) {
err = drgn_lazy_object_evaluate(member_object);
if (err)
return err;
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.
*/
uint64_t byte_size;
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 {
if (!drgn_type_has_size(member_object->obj.type)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"DW_TAG_member bit field type does not have size");
}
err = drgn_type_sizeof(member_object->obj.type,
&byte_size);
if (err)
return err;
}
*ret += 8 * byte_size - bit_offset - member_object->obj.bit_size;
} else {
*ret += bit_offset;
}
}
return NULL;
}
static struct drgn_error *
parse_member(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module, Dwarf_Die *die,
bool little_endian, bool can_be_incomplete_array,
struct drgn_compound_type_builder *builder)
{
struct drgn_error *err;
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;
}
struct drgn_dwarf_member_thunk_arg *thunk_arg =
malloc(sizeof(*thunk_arg));
if (!thunk_arg)
return &drgn_enomem;
thunk_arg->module = module;
thunk_arg->die = *die;
thunk_arg->can_be_incomplete_array = can_be_incomplete_array;
union drgn_lazy_object member_object;
drgn_lazy_object_init_thunk(&member_object, dbinfo->prog,
drgn_dwarf_member_thunk_fn, thunk_arg);
uint64_t bit_offset;
err = parse_member_offset(die, &member_object, little_endian,
&bit_offset);
if (err)
goto err;
err = drgn_compound_type_builder_add_member(builder, &member_object,
name, bit_offset);
if (err)
goto err;
return NULL;
err:
drgn_lazy_object_deinit(&member_object);
return err;
}
struct drgn_dwarf_die_thunk_arg {
struct drgn_debug_info_module *module;
Dwarf_Die die;
};
static struct drgn_error *
drgn_dwarf_template_type_parameter_thunk_fn(struct drgn_object *res, void *arg_)
{
struct drgn_error *err;
struct drgn_dwarf_die_thunk_arg *arg = arg_;
if (res) {
struct drgn_qualified_type qualified_type;
err = drgn_type_from_dwarf_attr(drgn_object_program(res)->_dbinfo,
arg->module, &arg->die, NULL,
true, true, NULL,
&qualified_type);
if (err)
return err;
err = drgn_object_set_absent(res, qualified_type, 0);
if (err)
return err;
}
free(arg);
return NULL;
}
static struct drgn_error *
drgn_dwarf_template_value_parameter_thunk_fn(struct drgn_object *res,
void *arg_)
{
struct drgn_error *err;
struct drgn_dwarf_die_thunk_arg *arg = arg_;
if (res) {
err = drgn_object_from_dwarf_variable(drgn_object_program(res)->_dbinfo,
arg->module, &arg->die,
res);
if (err)
return err;
}
free(arg);
return NULL;
}
static struct drgn_error *
parse_template_parameter(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module, Dwarf_Die *die,
drgn_object_thunk_fn *thunk_fn,
struct drgn_template_parameters_builder *builder)
{
char tag_buf[DW_TAG_BUF_LEN];
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_format(DRGN_ERROR_OTHER,
"%s has invalid DW_AT_name",
dwarf_tag_str(die, tag_buf));
}
} else {
name = NULL;
}
bool defaulted;
if (dwarf_flag_integrate(die, DW_AT_default_value, &defaulted)) {
return drgn_error_format(DRGN_ERROR_OTHER,
"%s has invalid DW_AT_default_value",
dwarf_tag_str(die, tag_buf));
}
struct drgn_dwarf_die_thunk_arg *thunk_arg =
malloc(sizeof(*thunk_arg));
if (!thunk_arg)
return &drgn_enomem;
thunk_arg->module = module;
thunk_arg->die = *die;
union drgn_lazy_object argument;
drgn_lazy_object_init_thunk(&argument, dbinfo->prog, thunk_fn,
thunk_arg);
struct drgn_error *err =
drgn_template_parameters_builder_add(builder, &argument, name,
defaulted);
if (err)
drgn_lazy_object_deinit(&argument);
return err;
}
static struct drgn_error *
drgn_compound_type_from_dwarf(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module,
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 != &drgn_not_found)
return err;
}
struct drgn_compound_type_builder builder;
drgn_compound_type_builder_init(&builder, dbinfo->prog, kind);
int size;
bool little_endian;
if (declaration) {
size = 0;
} else {
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));
}
dwarf_die_is_little_endian(die, false, &little_endian);
}
Dwarf_Die member = {}, child;
int r = dwarf_child(die, &child);
while (r == 0) {
switch (dwarf_tag(&child)) {
case DW_TAG_member:
if (!declaration) {
if (member.addr) {
err = parse_member(dbinfo, module,
&member,
little_endian, false,
&builder);
if (err)
goto err;
}
member = child;
}
break;
case DW_TAG_template_type_parameter:
err = parse_template_parameter(dbinfo, module, &child,
drgn_dwarf_template_type_parameter_thunk_fn,
&builder.template_builder);
if (err)
goto err;
break;
case DW_TAG_template_value_parameter:
err = parse_template_parameter(dbinfo, module, &child,
drgn_dwarf_template_value_parameter_thunk_fn,
&builder.template_builder);
if (err)
goto err;
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;
}
/*
* 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, module, &member, little_endian,
kind != DRGN_TYPE_UNION &&
builder.members.size > 0,
&builder);
if (err)
goto err;
}
err = drgn_compound_type_create(&builder, tag, size, !declaration, lang,
ret);
if (err)
goto err;
return NULL;
err:
drgn_compound_type_builder_deinit(&builder);
return err;
}
#if !_ELFUTILS_PREREQ(0, 175)
static Elf *dwelf_elf_begin(int fd)
{
return elf_begin(fd, ELF_C_READ_MMAP_PRIVATE, NULL);
}
#endif
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");
}
enum drgn_byte_order byte_order;
dwarf_die_byte_order(die, false, &byte_order);
return drgn_int_type_create(dbinfo->prog, "<unknown>", size, is_signed,
byte_order, lang, ret);
}
static struct drgn_error *
drgn_enum_type_from_dwarf(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module, 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 != &drgn_not_found)
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, module, &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,
struct drgn_debug_info_module *module,
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_attr(dbinfo, module, die,
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,
struct drgn_debug_info_module *module,
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_attr(dbinfo, module, die,
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 address_size;
err = drgn_program_address_size(dbinfo->prog, &address_size);
if (err)
return err;
size = address_size;
}
/*
* The DWARF 5 specification doesn't mention DW_AT_endianity for
* DW_TAG_pointer_type DIEs, and GCC as of version 10.2 doesn't emit it
* even for pointers stored in the opposite byte order (e.g., when using
* scalar_storage_order), but it probably should.
*/
enum drgn_byte_order byte_order;
dwarf_die_byte_order(die, false, &byte_order);
return drgn_pointer_type_create(dbinfo->prog, referenced_type, size,
byte_order, 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,
struct drgn_debug_info_module *module,
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_attr(dbinfo, module, die, 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 *
drgn_dwarf_formal_parameter_thunk_fn(struct drgn_object *res, void *arg_)
{
struct drgn_error *err;
struct drgn_dwarf_die_thunk_arg *arg = arg_;
if (res) {
struct drgn_qualified_type qualified_type;
err = drgn_type_from_dwarf_attr(drgn_object_program(res)->_dbinfo,
arg->module, &arg->die, NULL,
false, true, NULL,
&qualified_type);
if (err)
return err;
err = drgn_object_set_absent(res, qualified_type, 0);
if (err)
return err;
}
free(arg);
return NULL;
}
static struct drgn_error *
parse_formal_parameter(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module, 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_dwarf_die_thunk_arg *thunk_arg =
malloc(sizeof(*thunk_arg));
if (!thunk_arg)
return &drgn_enomem;
thunk_arg->module = module;
thunk_arg->die = *die;
union drgn_lazy_object default_argument;
drgn_lazy_object_init_thunk(&default_argument, dbinfo->prog,
drgn_dwarf_formal_parameter_thunk_fn,
thunk_arg);
struct drgn_error *err =
drgn_function_type_builder_add_parameter(builder,
&default_argument,
name);
if (err)
drgn_lazy_object_deinit(&default_argument);
return err;
}
static struct drgn_error *
drgn_function_type_from_dwarf(struct drgn_debug_info *dbinfo,
struct drgn_debug_info_module *module,
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, module, &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;
case DW_TAG_template_type_parameter:
err = parse_template_parameter(dbinfo, module, &child,
drgn_dwarf_template_type_parameter_thunk_fn,
&builder.template_builder);
if (err)
goto err;
break;
case DW_TAG_template_value_parameter:
err = parse_template_parameter(dbinfo, module, &child,
drgn_dwarf_template_value_parameter_thunk_fn,
&builder.template_builder);
if (err)
goto err;
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_attr(dbinfo, module, die, 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,
struct drgn_debug_info_module *module,
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");
}
/* If the DIE has a type unit signature, follow it. */
Dwarf_Die definition_die;
{
Dwarf_Attribute attr_mem, *attr;
if ((attr = dwarf_attr_integrate(die, DW_AT_signature,
&attr_mem))) {
if (!dwarf_formref_die(attr, &definition_die))
return drgn_error_libdw();
die = &definition_die;
}
}
/* If we got a declaration, try to find the definition. */
bool declaration;
if (dwarf_flag(die, DW_AT_declaration, &declaration))
return drgn_error_libdw();
if (declaration) {
uintptr_t die_addr;
if (drgn_dwarf_index_find_definition(&dbinfo->dindex,
(uintptr_t)die->addr,
&module, &die_addr)) {
Dwarf_Addr bias;
Dwarf *dwarf = dwfl_module_getdwarf(module->dwfl_module,
&bias);
if (!dwarf)
return drgn_error_libdwfl();
uintptr_t start =
(uintptr_t)module->scn_data[DRGN_SCN_DEBUG_INFO]->d_buf;
size_t size =
module->scn_data[DRGN_SCN_DEBUG_INFO]->d_size;
if (die_addr >= start && die_addr < start + size) {
if (!dwarf_offdie(dwarf, die_addr - start,
&definition_die))
return drgn_error_libdw();
} else {
start = (uintptr_t)module->scn_data[DRGN_SCN_DEBUG_TYPES]->d_buf;
/* Assume .debug_types */
if (!dwarf_offdie_types(dwarf, die_addr - start,
&definition_die))
return drgn_error_libdw();
}
die = &definition_die;
}
}
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, true, &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_attr(dbinfo, module, die, lang, true,
can_be_incomplete_array,
&entry.value.is_incomplete_array,
ret);
ret->qualifiers |= DRGN_QUALIFIER_CONST;
break;
case DW_TAG_restrict_type:
err = drgn_type_from_dwarf_attr(dbinfo, module, die, lang, true,
can_be_incomplete_array,
&entry.value.is_incomplete_array,
ret);
ret->qualifiers |= DRGN_QUALIFIER_RESTRICT;
break;
case DW_TAG_volatile_type:
err = drgn_type_from_dwarf_attr(dbinfo, module, die, lang, true,
can_be_incomplete_array,
&entry.value.is_incomplete_array,
ret);
ret->qualifiers |= DRGN_QUALIFIER_VOLATILE;
break;
case DW_TAG_atomic_type:
err = drgn_type_from_dwarf_attr(dbinfo, module, die, lang, true,
can_be_incomplete_array,
&entry.value.is_incomplete_array,
ret);
ret->qualifiers |= DRGN_QUALIFIER_ATOMIC;
break;
case DW_TAG_base_type:
err = drgn_base_type_from_dwarf(dbinfo, module, die, lang,
&ret->type);
break;
case DW_TAG_structure_type:
err = drgn_compound_type_from_dwarf(dbinfo, module, die, lang,
DRGN_TYPE_STRUCT,
&ret->type);
break;
case DW_TAG_union_type:
err = drgn_compound_type_from_dwarf(dbinfo, module, die, lang,
DRGN_TYPE_UNION,
&ret->type);
break;
case DW_TAG_class_type:
err = drgn_compound_type_from_dwarf(dbinfo, module, die, lang,
DRGN_TYPE_CLASS,
&ret->type);
break;
case DW_TAG_enumeration_type:
err = drgn_enum_type_from_dwarf(dbinfo, module, die, lang,
&ret->type);
break;
case DW_TAG_typedef:
err = drgn_typedef_type_from_dwarf(dbinfo, module, 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, module, die, lang,
&ret->type);
break;
case DW_TAG_array_type:
err = drgn_array_type_from_dwarf(dbinfo, module, 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, module, 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);
if (err)
return err;
if (die_matches_filename(&die, filename)) {
err = drgn_type_from_dwarf(dbinfo, index_die->module,
&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;
}
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;
err = drgn_dwarf_index_get_die(index_die, &die);
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,
index_die->module,
&die, name,
ret);
case DW_TAG_subprogram:
return drgn_object_from_dwarf_subprogram(dbinfo,
index_die->module,
&die, ret);
case DW_TAG_variable:
return drgn_object_from_dwarf_variable(dbinfo,
index_die->module,
&die, 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);
}
static struct drgn_error *
drgn_dwarf_cfi_next_encoded(struct drgn_debug_info_buffer *buffer,
uint8_t address_size, uint8_t encoding,
uint64_t func_addr, uint64_t *ret)
{
struct drgn_error *err;
/* Not currently used for CFI. */
if (encoding & DW_EH_PE_indirect) {
unknown_fde_encoding:
return binary_buffer_error(&buffer->bb,
"unknown EH encoding %#" PRIx8,
encoding);
}
size_t pos = (buffer->bb.pos -
(char *)buffer->module->scn_data[buffer->scn]->d_buf);
uint64_t base;
switch (encoding & 0x70) {
case DW_EH_PE_absptr:
base = 0;
break;
case DW_EH_PE_pcrel:
base = buffer->module->pcrel_base + pos;
break;
case DW_EH_PE_textrel:
base = buffer->module->textrel_base;
break;
case DW_EH_PE_datarel:
base = buffer->module->datarel_base;
break;
case DW_EH_PE_funcrel:
/* Relative to the FDE's initial location. */
base = func_addr;
break;
case DW_EH_PE_aligned:
base = 0;
if (pos % address_size != 0 &&
(err = binary_buffer_skip(&buffer->bb,
address_size - pos % address_size)))
return err;
break;
default:
goto unknown_fde_encoding;
}
uint64_t offset;
switch (encoding & 0xf) {
case DW_EH_PE_absptr:
if ((err = binary_buffer_next_uint(&buffer->bb, address_size,
&offset)))
return err;
break;
case DW_EH_PE_uleb128:
if ((err = binary_buffer_next_uleb128(&buffer->bb, &offset)))
return err;
break;
case DW_EH_PE_udata2:
if ((err = binary_buffer_next_u16_into_u64(&buffer->bb,
&offset)))
return err;
break;
case DW_EH_PE_udata4:
if ((err = binary_buffer_next_u32_into_u64(&buffer->bb,
&offset)))
return err;
break;
case DW_EH_PE_udata8:
if ((err = binary_buffer_next_u64(&buffer->bb, &offset)))
return err;
break;
case DW_EH_PE_sleb128:
if ((err = binary_buffer_next_sleb128_into_u64(&buffer->bb,
&offset)))
return err;
break;
case DW_EH_PE_sdata2:
if ((err = binary_buffer_next_s16_into_u64(&buffer->bb,
&offset)))
return err;
break;
case DW_EH_PE_sdata4:
if ((err = binary_buffer_next_s32_into_u64(&buffer->bb,
&offset)))
return err;
break;
case DW_EH_PE_sdata8:
if ((err = binary_buffer_next_s64_into_u64(&buffer->bb,
&offset)))
return err;
break;
default:
goto unknown_fde_encoding;
}
*ret = (base + offset) & uint_max(address_size);
return NULL;
}
static struct drgn_error *
drgn_parse_dwarf_cie(struct drgn_debug_info_module *module,
enum drgn_debug_info_scn scn, size_t cie_pointer,
struct drgn_dwarf_cie *cie)
{
bool is_eh = scn == DRGN_SCN_EH_FRAME;
struct drgn_error *err;
cie->is_eh = is_eh;
struct drgn_debug_info_buffer buffer;
drgn_debug_info_buffer_init(&buffer, module, scn);
buffer.bb.pos += cie_pointer;
uint32_t tmp;
if ((err = binary_buffer_next_u32(&buffer.bb, &tmp)))
return err;
bool is_64_bit = tmp == UINT32_C(0xffffffff);
uint64_t length;
if (is_64_bit) {
if ((err = binary_buffer_next_u64(&buffer.bb, &length)))
return err;
} else {
length = tmp;
}
if (length > buffer.bb.end - buffer.bb.pos) {
return binary_buffer_error(&buffer.bb,
"entry length is out of bounds");
}
buffer.bb.end = buffer.bb.pos + length;
uint64_t cie_id, expected_cie_id;
if (is_64_bit) {
if ((err = binary_buffer_next_u64(&buffer.bb, &cie_id)))
return err;
expected_cie_id = is_eh ? 0 : UINT64_C(0xffffffffffffffff);
} else {
if ((err = binary_buffer_next_u32_into_u64(&buffer.bb,
&cie_id)))
return err;
expected_cie_id = is_eh ? 0 : UINT64_C(0xffffffff);
}
if (cie_id != expected_cie_id)
return binary_buffer_error(&buffer.bb, "invalid CIE ID");
uint8_t version;
if ((err = binary_buffer_next_u8(&buffer.bb, &version)))
return err;
if (version < 1 || version == 2 || version > 4) {
return binary_buffer_error(&buffer.bb,
"unknown CIE version %" PRIu8,
version);
}
const char *augmentation;
size_t augmentation_len;
if ((err = binary_buffer_next_string(&buffer.bb, &augmentation,
&augmentation_len)))
return err;
cie->have_augmentation_length = augmentation[0] == 'z';
cie->signal_frame = false;
for (size_t i = 0; i < augmentation_len; i++) {
switch (augmentation[i]) {
case 'z':
if (i != 0)
goto unknown_augmentation;
break;
case 'L':
case 'P':
case 'R':
if (augmentation[0] != 'z')
goto unknown_augmentation;
break;
case 'S':
cie->signal_frame = true;
break;
default:
unknown_augmentation:
/*
* We could ignore this CIE and all FDEs that reference
* it or skip the augmentation if we have its length,
* but let's fail loudly so that we find out about
* missing support.
*/
return binary_buffer_error_at(&buffer.bb,
&augmentation[i],
"unknown CFI augmentation %s",
augmentation);
}
}
if (version >= 4) {
if ((err = binary_buffer_next_u8(&buffer.bb,
&cie->address_size)))
return err;
if (cie->address_size < 1 || cie->address_size > 8) {
return binary_buffer_error(&buffer.bb,
"unsupported address size %" PRIu8,
cie->address_size);
}
uint8_t segment_selector_size;
if ((err = binary_buffer_next_u8(&buffer.bb,
&segment_selector_size)))
return err;
if (segment_selector_size) {
return binary_buffer_error(&buffer.bb,
"unsupported segment selector size %" PRIu8,
segment_selector_size);
}
} else {
if (module->platform.flags & DRGN_PLATFORM_IS_64_BIT)
cie->address_size = 8;
else
cie->address_size = 4;
}
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&cie->code_alignment_factor)) ||
(err = binary_buffer_next_sleb128(&buffer.bb,
&cie->data_alignment_factor)))
return err;
uint64_t return_address_register;
if (version >= 3) {
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&return_address_register)))
return err;
} else {
if ((err = binary_buffer_next_u8_into_u64(&buffer.bb,
&return_address_register)))
return err;
}
cie->return_address_register =
module->platform.arch->dwarf_regno_to_internal(return_address_register);
if (cie->return_address_register == DRGN_REGISTER_NUMBER_UNKNOWN) {
return binary_buffer_error(&buffer.bb,
"unknown return address register");
}
cie->address_encoding = DW_EH_PE_absptr;
if (augmentation[0] == 'z') {
for (size_t i = 0; i < augmentation_len; i++) {
switch (augmentation[i]) {
case 'z':
if ((err = binary_buffer_skip_leb128(&buffer.bb)))
return err;
break;
case 'L':
if ((err = binary_buffer_skip(&buffer.bb, 1)))
return err;
break;
case 'P': {
uint8_t encoding;
if ((err = binary_buffer_next_u8(&buffer.bb, &encoding)))
return err;
/*
* We don't need the result, so don't bother
* dereferencing.
*/
encoding &= ~DW_EH_PE_indirect;
uint64_t unused;
if ((err = drgn_dwarf_cfi_next_encoded(&buffer,
cie->address_size,
encoding,
0,
&unused)))
return err;
break;
}
case 'R':
if ((err = binary_buffer_next_u8(&buffer.bb,
&cie->address_encoding)))
return err;
break;
}
}
}
cie->initial_instructions = buffer.bb.pos;
cie->initial_instructions_size = buffer.bb.end - buffer.bb.pos;
return NULL;
}
static struct drgn_error *
drgn_parse_dwarf_frames(struct drgn_debug_info_module *module,
enum drgn_debug_info_scn scn,
struct drgn_dwarf_cie_vector *cies,
struct drgn_dwarf_fde_vector *fdes)
{
bool is_eh = scn == DRGN_SCN_EH_FRAME;
struct drgn_error *err;
if (!module->scns[scn])
return NULL;
err = drgn_debug_info_module_cache_section(module, scn);
if (err)
return err;
Elf_Data *data = module->scn_data[scn];
struct drgn_debug_info_buffer buffer;
drgn_debug_info_buffer_init(&buffer, module, scn);
struct drgn_dwarf_cie_map cie_map = HASH_TABLE_INIT;
while (binary_buffer_has_next(&buffer.bb)) {
uint32_t tmp;
if ((err = binary_buffer_next_u32(&buffer.bb, &tmp)))
goto out;
bool is_64_bit = tmp == UINT32_C(0xffffffff);
uint64_t length;
if (is_64_bit) {
if ((err = binary_buffer_next_u64(&buffer.bb, &length)))
goto out;
} else {
length = tmp;
}
/*
* Technically, a length of zero is only a terminator in
* .eh_frame, but other consumers (binutils, elfutils, GDB)
* handle it the same way in .debug_frame.
*/
if (length == 0)
break;
if (length > buffer.bb.end - buffer.bb.pos) {
err = binary_buffer_error(&buffer.bb,
"entry length is out of bounds");
goto out;
}
buffer.bb.end = buffer.bb.pos + length;
/*
* The Linux Standard Base Core Specification [1] states that
* the CIE ID in .eh_frame is always 4 bytes. However, other
* consumers handle it the same as in .debug_frame (8 bytes for
* the 64-bit format).
*
* 1: https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
*/
uint64_t cie_pointer, cie_id;
if (is_64_bit) {
if ((err = binary_buffer_next_u64(&buffer.bb,
&cie_pointer)))
goto out;
cie_id = is_eh ? 0 : UINT64_C(0xffffffffffffffff);
} else {
if ((err = binary_buffer_next_u32_into_u64(&buffer.bb,
&cie_pointer)))
goto out;
cie_id = is_eh ? 0 : UINT64_C(0xffffffff);
}
if (cie_pointer != cie_id) {
if (is_eh) {
size_t pointer_offset =
(buffer.bb.pos
- (is_64_bit ? 8 : 4)
- (char *)data->d_buf);
if (cie_pointer > pointer_offset) {
err = binary_buffer_error(&buffer.bb,
"CIE pointer is out of bounds");
goto out;
}
cie_pointer = pointer_offset - cie_pointer;
} else if (cie_pointer > data->d_size) {
err = binary_buffer_error(&buffer.bb,
"CIE pointer is out of bounds");
goto out;
}
struct drgn_dwarf_fde *fde =
drgn_dwarf_fde_vector_append_entry(fdes);
if (!fde) {
err = &drgn_enomem;
goto out;
}
struct drgn_dwarf_cie_map_entry entry = {
.key = cie_pointer,
.value = cies->size,
};
struct drgn_dwarf_cie_map_iterator it;
int r = drgn_dwarf_cie_map_insert(&cie_map, &entry,
&it);
struct drgn_dwarf_cie *cie;
if (r > 0) {
cie = drgn_dwarf_cie_vector_append_entry(cies);
if (!cie) {
err = &drgn_enomem;
goto out;
}
err = drgn_parse_dwarf_cie(module, scn,
cie_pointer, cie);
if (err)
goto out;
} else if (r == 0) {
cie = &cies->data[it.entry->value];
} else {
err = &drgn_enomem;
goto out;
}
if ((err = drgn_dwarf_cfi_next_encoded(&buffer,
cie->address_size,
cie->address_encoding,
0,
&fde->initial_location)) ||
(err = drgn_dwarf_cfi_next_encoded(&buffer,
cie->address_size,
cie->address_encoding & 0xf,
0,
&fde->address_range)))
goto out;
if (cie->have_augmentation_length) {
uint64_t augmentation_length;
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&augmentation_length)))
goto out;
if (augmentation_length >
buffer.bb.end - buffer.bb.pos) {
err = binary_buffer_error(&buffer.bb,
"augmentation length is out of bounds");
goto out;
}
buffer.bb.pos += augmentation_length;
}
fde->cie = it.entry->value;
fde->instructions = buffer.bb.pos;
fde->instructions_size = buffer.bb.end - buffer.bb.pos;
}
buffer.bb.pos = buffer.bb.end;
buffer.bb.end = (const char *)data->d_buf + data->d_size;
}
err = NULL;
out:
drgn_dwarf_cie_map_deinit(&cie_map);
return err;
}
static void drgn_debug_info_cache_sh_addr(struct drgn_debug_info_module *module,
enum drgn_debug_info_scn scn,
uint64_t *addr)
{
if (module->scns[scn]) {
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr(module->scns[scn], &shdr_mem);
if (shdr)
*addr = shdr->sh_addr;
}
}
static int drgn_dwarf_fde_compar(const void *_a, const void *_b, void *arg)
{
const struct drgn_dwarf_fde *a = _a;
const struct drgn_dwarf_fde *b = _b;
const struct drgn_dwarf_cie *cies = arg;
if (a->initial_location < b->initial_location)
return -1;
else if (a->initial_location > b->initial_location)
return 1;
else
return cies[a->cie].is_eh - cies[b->cie].is_eh;
}
static struct drgn_error *
drgn_debug_info_parse_frames(struct drgn_debug_info_module *module)
{
struct drgn_error *err;
drgn_debug_info_cache_sh_addr(module, DRGN_SCN_EH_FRAME,
&module->pcrel_base);
drgn_debug_info_cache_sh_addr(module, DRGN_SCN_TEXT,
&module->textrel_base);
drgn_debug_info_cache_sh_addr(module, DRGN_SCN_GOT,
&module->datarel_base);
struct drgn_dwarf_cie_vector cies = VECTOR_INIT;
struct drgn_dwarf_fde_vector fdes = VECTOR_INIT;
err = drgn_parse_dwarf_frames(module, DRGN_SCN_DEBUG_FRAME, &cies,
&fdes);
if (err)
goto err;
err = drgn_parse_dwarf_frames(module, DRGN_SCN_EH_FRAME, &cies, &fdes);
if (err)
goto err;
drgn_dwarf_cie_vector_shrink_to_fit(&cies);
/*
* Sort FDEs and remove duplicates, preferring .debug_frame over
* .eh_frame.
*/
qsort_r(fdes.data, fdes.size, sizeof(fdes.data[0]),
drgn_dwarf_fde_compar, cies.data);
if (fdes.size > 0) {
size_t src = 1, dst = 1;
for (; src < fdes.size; src++) {
if (fdes.data[src].initial_location !=
fdes.data[dst - 1].initial_location) {
if (src != dst)
fdes.data[dst] = fdes.data[src];
dst++;
}
}
fdes.size = dst;
}
drgn_dwarf_fde_vector_shrink_to_fit(&fdes);
module->cies = cies.data;
module->fdes = fdes.data;
module->num_fdes = fdes.size;
return NULL;
err:
drgn_dwarf_fde_vector_deinit(&fdes);
drgn_dwarf_cie_vector_deinit(&cies);
return err;
}
static struct drgn_error *
drgn_debug_info_find_fde(struct drgn_debug_info_module *module,
uint64_t unbiased_pc, struct drgn_dwarf_fde **ret)
{
struct drgn_error *err;
if (!module->parsed_frames) {
err = drgn_debug_info_parse_frames(module);
if (err)
return err;
module->parsed_frames = true;
}
/* Binary search for the containing FDE. */
size_t lo = 0, hi = module->num_fdes;
while (lo < hi) {
size_t mid = lo + (hi - lo) / 2;
struct drgn_dwarf_fde *fde = &module->fdes[mid];
if (unbiased_pc < fde->initial_location) {
hi = mid;
} else if (unbiased_pc - fde->initial_location >=
fde->address_range) {
lo = mid + 1;
} else {
*ret = fde;
return NULL;
}
}
*ret = NULL;
return NULL;
}
static struct drgn_error *
drgn_dwarf_cfi_next_offset(struct drgn_debug_info_buffer *buffer, int64_t *ret)
{
struct drgn_error *err;
uint64_t offset;
if ((err = binary_buffer_next_uleb128(&buffer->bb, &offset)))
return err;
if (offset > INT64_MAX)
return binary_buffer_error(&buffer->bb, "offset is too large");
*ret = offset;
return NULL;
}
static struct drgn_error *
drgn_dwarf_cfi_next_offset_sf(struct drgn_debug_info_buffer *buffer,
struct drgn_dwarf_cie *cie, int64_t *ret)
{
struct drgn_error *err;
int64_t factored;
if ((err = binary_buffer_next_sleb128(&buffer->bb, &factored)))
return err;
if (__builtin_mul_overflow(factored, cie->data_alignment_factor, ret))
return binary_buffer_error(&buffer->bb, "offset is too large");
return NULL;
}
static struct drgn_error *
drgn_dwarf_cfi_next_offset_f(struct drgn_debug_info_buffer *buffer,
struct drgn_dwarf_cie *cie, int64_t *ret)
{
struct drgn_error *err;
uint64_t factored;
if ((err = binary_buffer_next_uleb128(&buffer->bb, &factored)))
return err;
if (__builtin_mul_overflow(factored, cie->data_alignment_factor, ret))
return binary_buffer_error(&buffer->bb, "offset is too large");
return NULL;
}
static struct drgn_error *
drgn_dwarf_cfi_next_block(struct drgn_debug_info_buffer *buffer,
const char **buf_ret, size_t *size_ret)
{
struct drgn_error *err;
uint64_t size;
if ((err = binary_buffer_next_uleb128(&buffer->bb, &size)))
return err;
if (size > buffer->bb.end - buffer->bb.pos) {
return binary_buffer_error(&buffer->bb,
"block is out of bounds");
}
*buf_ret = buffer->bb.pos;
buffer->bb.pos += size;
*size_ret = size;
return NULL;
}
static struct drgn_error *
drgn_eval_dwarf_cfi(struct drgn_debug_info_module *module,
struct drgn_dwarf_fde *fde,
const struct drgn_cfi_row *initial_row, uint64_t target,
const char *instructions, size_t instructions_size,
struct drgn_cfi_row **row)
{
struct drgn_error *err;
drgn_register_number (*dwarf_regno_to_internal)(uint64_t) =
module->platform.arch->dwarf_regno_to_internal;
struct drgn_dwarf_cie *cie = &module->cies[fde->cie];
uint64_t pc = fde->initial_location;
struct drgn_cfi_row_vector state_stack = VECTOR_INIT;
struct drgn_debug_info_buffer buffer;
drgn_debug_info_buffer_init(&buffer, module,
cie->is_eh ?
DRGN_SCN_EH_FRAME : DRGN_SCN_DEBUG_FRAME);
buffer.bb.pos = instructions;
buffer.bb.end = instructions + instructions_size;
while (binary_buffer_has_next(&buffer.bb)) {
uint8_t opcode;
if ((err = binary_buffer_next_u8(&buffer.bb, &opcode)))
goto out;
uint64_t dwarf_regno;
drgn_register_number regno;
struct drgn_cfi_rule rule;
uint64_t tmp;
switch ((opcode & 0xc0) ? (opcode & 0xc0) : opcode) {
case DW_CFA_set_loc:
if (!initial_row)
goto invalid_for_initial;
if ((err = drgn_dwarf_cfi_next_encoded(&buffer,
cie->address_size,
cie->address_encoding,
fde->initial_location,
&tmp)))
goto out;
if (tmp <= pc) {
err = binary_buffer_error(&buffer.bb,
"DW_CFA_set_loc location is not greater than current location");
goto out;
}
pc = tmp;
if (pc > target)
goto found;
break;
case DW_CFA_advance_loc:
if (!initial_row)
goto invalid_for_initial;
tmp = opcode & 0x3f;
goto advance_loc;
case DW_CFA_advance_loc1:
if (!initial_row)
goto invalid_for_initial;
if ((err = binary_buffer_next_u8_into_u64(&buffer.bb,
&tmp)))
goto out;
goto advance_loc;
case DW_CFA_advance_loc2:
if (!initial_row)
goto invalid_for_initial;
if ((err = binary_buffer_next_u16_into_u64(&buffer.bb,
&tmp)))
goto out;
goto advance_loc;
case DW_CFA_advance_loc4:
if (!initial_row)
goto invalid_for_initial;
if ((err = binary_buffer_next_u32_into_u64(&buffer.bb,
&tmp)))
goto out;
advance_loc:
if (__builtin_mul_overflow(tmp,
cie->code_alignment_factor,
&tmp) ||
__builtin_add_overflow(pc, tmp, &pc) ||
pc > uint_max(cie->address_size)) {
err = drgn_error_create(DRGN_ERROR_OTHER,
"DW_CFA_advance_loc* overflows location");
goto out;
}
if (pc > target)
goto found;
break;
case DW_CFA_def_cfa:
rule.kind = DRGN_CFI_RULE_REGISTER_PLUS_OFFSET;
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)) ||
(err = drgn_dwarf_cfi_next_offset(&buffer, &rule.offset)))
goto out;
if ((rule.regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
rule.kind = DRGN_CFI_RULE_UNDEFINED;
goto set_cfa;
case DW_CFA_def_cfa_sf:
rule.kind = DRGN_CFI_RULE_REGISTER_PLUS_OFFSET;
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)) ||
(err = drgn_dwarf_cfi_next_offset_sf(&buffer, cie,
&rule.offset)))
goto out;
if ((rule.regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
rule.kind = DRGN_CFI_RULE_UNDEFINED;
goto set_cfa;
case DW_CFA_def_cfa_register:
drgn_cfi_row_get_cfa(*row, &rule);
if (rule.kind != DRGN_CFI_RULE_REGISTER_PLUS_OFFSET) {
err = binary_buffer_error(&buffer.bb,
"DW_CFA_def_cfa_register with incompatible CFA rule");
goto out;
}
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)))
goto out;
if ((rule.regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
rule.kind = DRGN_CFI_RULE_UNDEFINED;
goto set_cfa;
case DW_CFA_def_cfa_offset:
drgn_cfi_row_get_cfa(*row, &rule);
if (rule.kind != DRGN_CFI_RULE_REGISTER_PLUS_OFFSET) {
err = binary_buffer_error(&buffer.bb,
"DW_CFA_def_cfa_offset with incompatible CFA rule");
goto out;
}
if ((err = drgn_dwarf_cfi_next_offset(&buffer,
&rule.offset)))
goto out;
goto set_cfa;
case DW_CFA_def_cfa_offset_sf:
drgn_cfi_row_get_cfa(*row, &rule);
if (rule.kind != DRGN_CFI_RULE_REGISTER_PLUS_OFFSET) {
err = binary_buffer_error(&buffer.bb,
"DW_CFA_def_cfa_offset_sf with incompatible CFA rule");
goto out;
}
if ((err = drgn_dwarf_cfi_next_offset_sf(&buffer, cie,
&rule.offset)))
goto out;
goto set_cfa;
case DW_CFA_def_cfa_expression:
rule.kind = DRGN_CFI_RULE_DWARF_EXPRESSION;
rule.push_cfa = false;
if ((err = drgn_dwarf_cfi_next_block(&buffer,
&rule.expr,
&rule.expr_size)))
goto out;
set_cfa:
if (!drgn_cfi_row_set_cfa(row, &rule)) {
err = &drgn_enomem;
goto out;
}
break;
case DW_CFA_undefined:
rule.kind = DRGN_CFI_RULE_UNDEFINED;
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)))
goto out;
if ((regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
break;
goto set_reg;
case DW_CFA_same_value:
rule.kind = DRGN_CFI_RULE_REGISTER_PLUS_OFFSET;
rule.offset = 0;
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)))
goto out;
if ((regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
break;
rule.regno = regno;
goto set_reg;
case DW_CFA_offset:
rule.kind = DRGN_CFI_RULE_AT_CFA_PLUS_OFFSET;
if ((err = drgn_dwarf_cfi_next_offset_f(&buffer, cie,
&rule.offset)))
goto out;
if ((regno = dwarf_regno_to_internal(opcode & 0x3f)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
break;
goto set_reg;
case DW_CFA_offset_extended:
rule.kind = DRGN_CFI_RULE_AT_CFA_PLUS_OFFSET;
goto reg_offset_f;
case DW_CFA_offset_extended_sf:
rule.kind = DRGN_CFI_RULE_AT_CFA_PLUS_OFFSET;
goto reg_offset_sf;
case DW_CFA_val_offset:
rule.kind = DRGN_CFI_RULE_CFA_PLUS_OFFSET;
reg_offset_f:
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)) ||
(err = drgn_dwarf_cfi_next_offset_f(&buffer, cie,
&rule.offset)))
goto out;
if ((regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
break;
goto set_reg;
case DW_CFA_val_offset_sf:
rule.kind = DRGN_CFI_RULE_CFA_PLUS_OFFSET;
reg_offset_sf:
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)) ||
(err = drgn_dwarf_cfi_next_offset_sf(&buffer, cie,
&rule.offset)))
goto out;
if ((regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
break;
goto set_reg;
case DW_CFA_register: {
rule.kind = DRGN_CFI_RULE_REGISTER_PLUS_OFFSET;
rule.offset = 0;
uint64_t dwarf_regno2;
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)) ||
(err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno2)))
goto out;
if ((regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
break;
if ((rule.regno = dwarf_regno_to_internal(dwarf_regno2)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
rule.kind = DRGN_CFI_RULE_UNDEFINED;
goto set_reg;
}
case DW_CFA_expression:
rule.kind = DRGN_CFI_RULE_AT_DWARF_EXPRESSION;
goto reg_expression;
case DW_CFA_val_expression:
rule.kind = DRGN_CFI_RULE_DWARF_EXPRESSION;
reg_expression:
rule.push_cfa = true;
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)) ||
(err = drgn_dwarf_cfi_next_block(&buffer,
&rule.expr,
&rule.expr_size)))
goto out;
if ((regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
break;
goto set_reg;
case DW_CFA_restore:
if (!initial_row)
goto invalid_for_initial;
dwarf_regno = opcode & 0x3f;
goto restore;
case DW_CFA_restore_extended:
if (!initial_row) {
invalid_for_initial:
err = binary_buffer_error(&buffer.bb,
"invalid initial DWARF CFI opcode %#" PRIx8,
opcode);
goto out;
}
if ((err = binary_buffer_next_uleb128(&buffer.bb,
&dwarf_regno)))
goto out;
restore:
if ((regno = dwarf_regno_to_internal(dwarf_regno)) ==
DRGN_REGISTER_NUMBER_UNKNOWN)
break;
drgn_cfi_row_get_register(initial_row, regno, &rule);
set_reg:
if (!drgn_cfi_row_set_register(row, regno, &rule)) {
err = &drgn_enomem;
goto out;
}
break;
case DW_CFA_remember_state: {
struct drgn_cfi_row **state =
drgn_cfi_row_vector_append_entry(&state_stack);
if (!state) {
err = &drgn_enomem;
goto out;
}
*state = drgn_empty_cfi_row;
if (!drgn_cfi_row_copy(state, *row)) {
err = &drgn_enomem;
goto out;
}
break;
}
case DW_CFA_restore_state:
if (state_stack.size == 0) {
err = binary_buffer_error(&buffer.bb,
"DW_CFA_restore_state with empty state stack");
goto out;
}
drgn_cfi_row_destroy(*row);
*row = state_stack.data[--state_stack.size];
break;
case DW_CFA_nop:
break;
default:
err = binary_buffer_error(&buffer.bb,
"unknown DWARF CFI opcode %#" PRIx8,
opcode);
goto out;
}
}
found:
err = NULL;
out:
for (size_t i = 0; i < state_stack.size; i++)
drgn_cfi_row_destroy(state_stack.data[i]);
drgn_cfi_row_vector_deinit(&state_stack);
return err;
}
static struct drgn_error *
drgn_debug_info_find_cfi_in_fde(struct drgn_debug_info_module *module,
struct drgn_dwarf_fde *fde,
uint64_t unbiased_pc, struct drgn_cfi_row **ret)
{
struct drgn_error *err;
struct drgn_dwarf_cie *cie = &module->cies[fde->cie];
struct drgn_cfi_row *initial_row =
(struct drgn_cfi_row *)module->platform.arch->default_dwarf_cfi_row;
err = drgn_eval_dwarf_cfi(module, fde, NULL, unbiased_pc,
cie->initial_instructions,
cie->initial_instructions_size, &initial_row);
if (err)
goto out;
if (!drgn_cfi_row_copy(ret, initial_row)) {
err = &drgn_enomem;
goto out;
}
err = drgn_eval_dwarf_cfi(module, fde, initial_row, unbiased_pc,
fde->instructions, fde->instructions_size,
ret);
out:
drgn_cfi_row_destroy(initial_row);
return err;
}
static struct drgn_error *
drgn_debug_info_find_dwarf_cfi(struct drgn_debug_info_module *module,
uint64_t unbiased_pc,
struct drgn_cfi_row **row_ret,
bool *interrupted_ret,
drgn_register_number *ret_addr_regno_ret)
{
struct drgn_error *err;
struct drgn_dwarf_fde *fde;
err = drgn_debug_info_find_fde(module, unbiased_pc, &fde);
if (err)
return err;
if (!fde)
return &drgn_not_found;
err = drgn_debug_info_find_cfi_in_fde(module, fde, unbiased_pc,
row_ret);
if (err)
return err;
*interrupted_ret = module->cies[fde->cie].signal_frame;
*ret_addr_regno_ret = module->cies[fde->cie].return_address_register;
return NULL;
}
/*
* Get the program counter of an ORC entry directly from the .orc_unwind_ip
* section.
*/
static inline uint64_t drgn_raw_orc_pc(struct drgn_debug_info_module *module,
size_t i)
{
int32_t offset;
memcpy(&offset,
(int32_t *)module->scn_data[DRGN_SCN_ORC_UNWIND_IP]->d_buf + i,
sizeof(offset));
if (drgn_platform_bswap(&module->platform))
offset = bswap_32(offset);
return module->orc_pc_base + UINT64_C(4) * i + offset;
}
static int compare_orc_entries(const void *a, const void *b, void *arg)
{
struct drgn_debug_info_module *module = arg;
size_t index_a = *(size_t *)a;
size_t index_b = *(size_t *)b;
uint64_t pc_a = drgn_raw_orc_pc(module, index_a);
uint64_t pc_b = drgn_raw_orc_pc(module, index_b);
if (pc_a < pc_b)
return -1;
else if (pc_a > pc_b)
return 1;
/*
* If two entries have the same PC, then one is probably a "terminator"
* at the end of a compilation unit. Prefer the real entry.
*/
const struct drgn_orc_entry *entries =
module->scn_data[DRGN_SCN_ORC_UNWIND]->d_buf;
uint16_t flags_a, flags_b;
memcpy(&flags_a, &entries[index_a].flags, sizeof(flags_a));
memcpy(&flags_b, &entries[index_b].flags, sizeof(flags_b));
if (drgn_platform_bswap(&module->platform)) {
flags_a = bswap_16(flags_a);
flags_b = bswap_16(flags_b);
}
return (drgn_orc_flags_is_terminator(flags_b)
- drgn_orc_flags_is_terminator(flags_a));
}
static size_t keep_orc_entry(struct drgn_debug_info_module *module,
size_t *indices, size_t num_entries, size_t i)
{
const struct drgn_orc_entry *entries =
module->scn_data[DRGN_SCN_ORC_UNWIND]->d_buf;
if (num_entries > 0 &&
memcmp(&entries[indices[num_entries - 1]], &entries[indices[i]],
sizeof(entries[0])) == 0) {
/*
* The previous entry is identical to this one, so we can skip
* this entry (which effectively merges it into the previous
* one). This usually happens for "terminator" entries.
*/
return num_entries;
}
indices[num_entries] = indices[i];
return num_entries + 1;
}
/*
* The vast majority of ORC entries are redundant with DWARF CFI, and it's a
* waste to store and binary search those entries. This removes ORC entries that
* are entirely shadowed by DWARF FDEs.
*/
static size_t remove_fdes_from_orc(struct drgn_debug_info_module *module,
size_t *indices, size_t num_entries)
{
if (module->num_fdes == 0)
return num_entries;
struct drgn_dwarf_fde *fde = module->fdes;
struct drgn_dwarf_fde *last_fde = &module->fdes[module->num_fdes - 1];
size_t new_num_entries = 0;
/* Keep any entries that start before the first DWARF FDE. */
uint64_t start_pc;
for (;;) {
start_pc = drgn_raw_orc_pc(module, new_num_entries);
if (fde->initial_location <= start_pc)
break;
new_num_entries++;
if (new_num_entries == num_entries)
return num_entries;
}
for (size_t i = new_num_entries; i < num_entries - 1; i++) {
uint64_t end_pc = drgn_raw_orc_pc(module, i + 1);
/*
* Find the last FDE that starts at or before the current ORC
* entry.
*/
while (fde != last_fde && fde[1].initial_location <= start_pc)
fde++;
/*
* Check whether the current ORC entry is completely covered by
* one or more FDEs.
*/
while (end_pc - fde->initial_location > fde->address_range) {
/*
* The current FDE doesn't cover the current ORC entry.
*/
if (fde == last_fde) {
/*
* There are no more FDEs. Keep the remaining
* ORC entries.
*/
if (i != new_num_entries) {
memmove(&indices[new_num_entries],
&indices[i],
(num_entries - i) *
sizeof(indices[0]));
}
return new_num_entries + (num_entries - i);
}
if (fde[1].initial_location - fde->initial_location
> fde->address_range) {
/*
* There is a gap between the current FDE and
* the next FDE that exposes the current ORC
* entry. Keep it.
*/
new_num_entries = keep_orc_entry(module,
indices,
new_num_entries,
i);
break;
}
fde++;
}
start_pc = end_pc;
}
/* We don't know where the last ORC entry ends, so always keep it. */
return keep_orc_entry(module, indices, new_num_entries,
num_entries - 1);
}
static struct drgn_error *
drgn_debug_info_parse_orc(struct drgn_debug_info_module *module)
{
struct drgn_error *err;
if (!module->platform.arch->orc_to_cfi ||
!module->scns[DRGN_SCN_ORC_UNWIND_IP] ||
!module->scns[DRGN_SCN_ORC_UNWIND])
return NULL;
GElf_Shdr shdr_mem, *shdr;
shdr = gelf_getshdr(module->scns[DRGN_SCN_ORC_UNWIND_IP], &shdr_mem);
if (!shdr)
return drgn_error_libelf();
module->orc_pc_base = shdr->sh_addr;
err = drgn_debug_info_module_cache_section(module,
DRGN_SCN_ORC_UNWIND_IP);
if (err)
return err;
err = drgn_debug_info_module_cache_section(module, DRGN_SCN_ORC_UNWIND);
if (err)
return err;
Elf_Data *orc_unwind_ip = module->scn_data[DRGN_SCN_ORC_UNWIND_IP];
Elf_Data *orc_unwind = module->scn_data[DRGN_SCN_ORC_UNWIND];
size_t num_entries = orc_unwind_ip->d_size / sizeof(int32_t);
if (orc_unwind_ip->d_size % sizeof(int32_t) != 0 ||
orc_unwind->d_size % sizeof(struct drgn_orc_entry) != 0 ||
orc_unwind->d_size / sizeof(struct drgn_orc_entry) != num_entries) {
return drgn_error_create(DRGN_ERROR_OTHER,
".orc_unwind_ip and/or .orc_unwind has invalid size");
}
if (!num_entries)
return NULL;
size_t *indices = malloc_array(num_entries, sizeof(indices[0]));
if (!indices)
return &drgn_enomem;
for (size_t i = 0; i < num_entries; i++)
indices[i] = i;
/*
* Sort the ORC entries for binary search. Since Linux kernel commit
* f14bf6a350df ("x86/unwind/orc: Remove boot-time ORC unwind tables
* sorting") (in v5.6), this is already sorted for vmlinux, so only sort
* it if necessary.
*/
for (size_t i = 1; i < num_entries; i++) {
if (compare_orc_entries(&indices[i - 1], &indices[i],
module) > 0) {
qsort_r(indices, num_entries, sizeof(indices[0]),
compare_orc_entries, module);
break;
}
}
num_entries = remove_fdes_from_orc(module, indices, num_entries);
int32_t *pc_offsets = malloc_array(num_entries, sizeof(pc_offsets[0]));
if (!pc_offsets) {
err = &drgn_enomem;
goto out;
}
struct drgn_orc_entry *entries = malloc_array(num_entries,
sizeof(entries[0]));
if (!entries) {
free(pc_offsets);
err = &drgn_enomem;
goto out;
}
const int32_t *orig_offsets = orc_unwind_ip->d_buf;
const struct drgn_orc_entry *orig_entries = orc_unwind->d_buf;
bool bswap = drgn_platform_bswap(&module->platform);
for (size_t i = 0; i < num_entries; i++) {
size_t index = indices[i];
int32_t offset;
memcpy(&offset, &orig_offsets[index], sizeof(offset));
struct drgn_orc_entry entry;
memcpy(&entry, &orig_entries[index], sizeof(entry));
if (bswap) {
offset = bswap_32(offset);
entry.sp_offset = bswap_16(entry.sp_offset);
entry.bp_offset = bswap_16(entry.bp_offset);
entry.flags = bswap_16(entry.flags);
}
pc_offsets[i] = UINT64_C(4) * index + offset - UINT64_C(4) * i;
entries[i] = entry;
}
module->orc_pc_offsets = pc_offsets;
module->orc_entries = entries;
module->num_orc_entries = num_entries;
err = NULL;
out:
free(indices);
return err;
}
static inline uint64_t drgn_orc_pc(struct drgn_debug_info_module *module,
size_t i)
{
return module->orc_pc_base + UINT64_C(4) * i + module->orc_pc_offsets[i];
}
static struct drgn_error *
drgn_debug_info_find_orc_cfi(struct drgn_debug_info_module *module,
uint64_t unbiased_pc,
struct drgn_cfi_row **row_ret,
bool *interrupted_ret,
drgn_register_number *ret_addr_regno_ret)
{
struct drgn_error *err;
if (!module->parsed_orc) {
err = drgn_debug_info_parse_orc(module);
if (err)
return err;
module->parsed_orc = true;
}
/*
* We don't know the maximum program counter covered by the ORC data,
* but the last entry seems to always be a terminator, so it doesn't
* matter. All addresses beyond the max will fall into the last entry.
*/
if (!module->num_orc_entries || unbiased_pc < drgn_orc_pc(module, 0))
return &drgn_not_found;
size_t lo = 0, hi = module->num_orc_entries, found = 0;
while (lo < hi) {
size_t mid = lo + (hi - lo) / 2;
if (drgn_orc_pc(module, mid) <= unbiased_pc) {
found = mid;
lo = mid + 1;
} else {
hi = mid;
}
}
return module->platform.arch->orc_to_cfi(&module->orc_entries[found],
row_ret, interrupted_ret,
ret_addr_regno_ret);
}
struct drgn_error *
drgn_debug_info_module_find_cfi(struct drgn_program *prog,
struct drgn_debug_info_module *module,
uint64_t pc, struct drgn_cfi_row **row_ret,
bool *interrupted_ret,
drgn_register_number *ret_addr_regno_ret)
{
struct drgn_error *err;
Dwarf_Addr bias;
dwfl_module_info(module->dwfl_module, NULL, NULL, NULL, &bias, NULL,
NULL, NULL);
uint64_t unbiased_pc = pc - bias;
if (prog->prefer_orc_unwinder) {
err = drgn_debug_info_find_orc_cfi(module, unbiased_pc, row_ret,
interrupted_ret,
ret_addr_regno_ret);
if (err != &drgn_not_found)
return err;
return drgn_debug_info_find_dwarf_cfi(module, unbiased_pc,
row_ret, interrupted_ret,
ret_addr_regno_ret);
} else {
err = drgn_debug_info_find_dwarf_cfi(module, unbiased_pc,
row_ret, interrupted_ret,
ret_addr_regno_ret);
if (err != &drgn_not_found)
return err;
return drgn_debug_info_find_orc_cfi(module, unbiased_pc,
row_ret, interrupted_ret,
ret_addr_regno_ret);
}
}
struct drgn_error *
drgn_eval_cfi_dwarf_expression(struct drgn_program *prog,
const struct drgn_cfi_rule *rule,
const struct drgn_register_state *regs,
void *buf, size_t size)
{
struct drgn_error *err;
struct uint64_vector stack = VECTOR_INIT;
if (rule->push_cfa) {
struct optional_uint64 cfa = drgn_register_state_get_cfa(regs);
if (!cfa.has_value) {
err = &drgn_not_found;
goto out;
}
if (!uint64_vector_append(&stack, &cfa.value)) {
err = &drgn_enomem;
goto out;
}
}
struct drgn_dwarf_expression_buffer buffer;
drgn_dwarf_expression_buffer_init(&buffer, regs->module, rule->expr,
rule->expr_size);
err = drgn_eval_dwarf_expression(prog, &buffer, &stack, regs);
if (err)
goto out;
if (stack.size == 0) {
err = &drgn_not_found;
} else if (rule->kind == DRGN_CFI_RULE_AT_DWARF_EXPRESSION) {
err = drgn_program_read_memory(prog, buf,
stack.data[stack.size - 1], size,
false);
} else {
copy_lsbytes(buf, size,
drgn_platform_is_little_endian(&prog->platform),
&stack.data[stack.size - 1], sizeof(uint64_t),
HOST_LITTLE_ENDIAN);
err = NULL;
}
out:
uint64_vector_deinit(&stack);
return err;
}
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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