![Josh Poimboeuf](/assets/img/avatar_default.png)
If a nonexistent file is supplied to objtool, it complains with a non-helpful error: open: No such file or directory Improve it to: objtool: Can't open 'foo': No such file or directory Reported-by: Markus <M4rkusXXL@web.de> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/406a3d00a21225eee2819844048e17f68523ccf6.1516025651.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
624 lines
12 KiB
C
624 lines
12 KiB
C
/*
|
|
* elf.c - ELF access library
|
|
*
|
|
* Adapted from kpatch (https://github.com/dynup/kpatch):
|
|
* Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
|
|
* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version 2
|
|
* of the License, or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <fcntl.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <errno.h>
|
|
|
|
#include "elf.h"
|
|
#include "warn.h"
|
|
|
|
struct section *find_section_by_name(struct elf *elf, const char *name)
|
|
{
|
|
struct section *sec;
|
|
|
|
list_for_each_entry(sec, &elf->sections, list)
|
|
if (!strcmp(sec->name, name))
|
|
return sec;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct section *find_section_by_index(struct elf *elf,
|
|
unsigned int idx)
|
|
{
|
|
struct section *sec;
|
|
|
|
list_for_each_entry(sec, &elf->sections, list)
|
|
if (sec->idx == idx)
|
|
return sec;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
|
|
{
|
|
struct section *sec;
|
|
struct symbol *sym;
|
|
|
|
list_for_each_entry(sec, &elf->sections, list)
|
|
hash_for_each_possible(sec->symbol_hash, sym, hash, idx)
|
|
if (sym->idx == idx)
|
|
return sym;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
|
|
{
|
|
struct symbol *sym;
|
|
|
|
list_for_each_entry(sym, &sec->symbol_list, list)
|
|
if (sym->type != STT_SECTION &&
|
|
sym->offset == offset)
|
|
return sym;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
struct symbol *find_symbol_containing(struct section *sec, unsigned long offset)
|
|
{
|
|
struct symbol *sym;
|
|
|
|
list_for_each_entry(sym, &sec->symbol_list, list)
|
|
if (sym->type != STT_SECTION &&
|
|
offset >= sym->offset && offset < sym->offset + sym->len)
|
|
return sym;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset,
|
|
unsigned int len)
|
|
{
|
|
struct rela *rela;
|
|
unsigned long o;
|
|
|
|
if (!sec->rela)
|
|
return NULL;
|
|
|
|
for (o = offset; o < offset + len; o++)
|
|
hash_for_each_possible(sec->rela->rela_hash, rela, hash, o)
|
|
if (rela->offset == o)
|
|
return rela;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
struct rela *find_rela_by_dest(struct section *sec, unsigned long offset)
|
|
{
|
|
return find_rela_by_dest_range(sec, offset, 1);
|
|
}
|
|
|
|
struct symbol *find_containing_func(struct section *sec, unsigned long offset)
|
|
{
|
|
struct symbol *func;
|
|
|
|
list_for_each_entry(func, &sec->symbol_list, list)
|
|
if (func->type == STT_FUNC && offset >= func->offset &&
|
|
offset < func->offset + func->len)
|
|
return func;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static int read_sections(struct elf *elf)
|
|
{
|
|
Elf_Scn *s = NULL;
|
|
struct section *sec;
|
|
size_t shstrndx, sections_nr;
|
|
int i;
|
|
|
|
if (elf_getshdrnum(elf->elf, §ions_nr)) {
|
|
WARN_ELF("elf_getshdrnum");
|
|
return -1;
|
|
}
|
|
|
|
if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
|
|
WARN_ELF("elf_getshdrstrndx");
|
|
return -1;
|
|
}
|
|
|
|
for (i = 0; i < sections_nr; i++) {
|
|
sec = malloc(sizeof(*sec));
|
|
if (!sec) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
memset(sec, 0, sizeof(*sec));
|
|
|
|
INIT_LIST_HEAD(&sec->symbol_list);
|
|
INIT_LIST_HEAD(&sec->rela_list);
|
|
hash_init(sec->rela_hash);
|
|
hash_init(sec->symbol_hash);
|
|
|
|
list_add_tail(&sec->list, &elf->sections);
|
|
|
|
s = elf_getscn(elf->elf, i);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return -1;
|
|
}
|
|
|
|
sec->idx = elf_ndxscn(s);
|
|
|
|
if (!gelf_getshdr(s, &sec->sh)) {
|
|
WARN_ELF("gelf_getshdr");
|
|
return -1;
|
|
}
|
|
|
|
sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
|
|
if (!sec->name) {
|
|
WARN_ELF("elf_strptr");
|
|
return -1;
|
|
}
|
|
|
|
if (sec->sh.sh_size != 0) {
|
|
sec->data = elf_getdata(s, NULL);
|
|
if (!sec->data) {
|
|
WARN_ELF("elf_getdata");
|
|
return -1;
|
|
}
|
|
if (sec->data->d_off != 0 ||
|
|
sec->data->d_size != sec->sh.sh_size) {
|
|
WARN("unexpected data attributes for %s",
|
|
sec->name);
|
|
return -1;
|
|
}
|
|
}
|
|
sec->len = sec->sh.sh_size;
|
|
}
|
|
|
|
/* sanity check, one more call to elf_nextscn() should return NULL */
|
|
if (elf_nextscn(elf->elf, s)) {
|
|
WARN("section entry mismatch");
|
|
return -1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int read_symbols(struct elf *elf)
|
|
{
|
|
struct section *symtab;
|
|
struct symbol *sym;
|
|
struct list_head *entry, *tmp;
|
|
int symbols_nr, i;
|
|
|
|
symtab = find_section_by_name(elf, ".symtab");
|
|
if (!symtab) {
|
|
WARN("missing symbol table");
|
|
return -1;
|
|
}
|
|
|
|
symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
|
|
|
|
for (i = 0; i < symbols_nr; i++) {
|
|
sym = malloc(sizeof(*sym));
|
|
if (!sym) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
memset(sym, 0, sizeof(*sym));
|
|
|
|
sym->idx = i;
|
|
|
|
if (!gelf_getsym(symtab->data, i, &sym->sym)) {
|
|
WARN_ELF("gelf_getsym");
|
|
goto err;
|
|
}
|
|
|
|
sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
|
|
sym->sym.st_name);
|
|
if (!sym->name) {
|
|
WARN_ELF("elf_strptr");
|
|
goto err;
|
|
}
|
|
|
|
sym->type = GELF_ST_TYPE(sym->sym.st_info);
|
|
sym->bind = GELF_ST_BIND(sym->sym.st_info);
|
|
|
|
if (sym->sym.st_shndx > SHN_UNDEF &&
|
|
sym->sym.st_shndx < SHN_LORESERVE) {
|
|
sym->sec = find_section_by_index(elf,
|
|
sym->sym.st_shndx);
|
|
if (!sym->sec) {
|
|
WARN("couldn't find section for symbol %s",
|
|
sym->name);
|
|
goto err;
|
|
}
|
|
if (sym->type == STT_SECTION) {
|
|
sym->name = sym->sec->name;
|
|
sym->sec->sym = sym;
|
|
}
|
|
} else
|
|
sym->sec = find_section_by_index(elf, 0);
|
|
|
|
sym->offset = sym->sym.st_value;
|
|
sym->len = sym->sym.st_size;
|
|
|
|
/* sorted insert into a per-section list */
|
|
entry = &sym->sec->symbol_list;
|
|
list_for_each_prev(tmp, &sym->sec->symbol_list) {
|
|
struct symbol *s;
|
|
|
|
s = list_entry(tmp, struct symbol, list);
|
|
|
|
if (sym->offset > s->offset) {
|
|
entry = tmp;
|
|
break;
|
|
}
|
|
|
|
if (sym->offset == s->offset && sym->len >= s->len) {
|
|
entry = tmp;
|
|
break;
|
|
}
|
|
}
|
|
list_add(&sym->list, entry);
|
|
hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx);
|
|
}
|
|
|
|
return 0;
|
|
|
|
err:
|
|
free(sym);
|
|
return -1;
|
|
}
|
|
|
|
static int read_relas(struct elf *elf)
|
|
{
|
|
struct section *sec;
|
|
struct rela *rela;
|
|
int i;
|
|
unsigned int symndx;
|
|
|
|
list_for_each_entry(sec, &elf->sections, list) {
|
|
if (sec->sh.sh_type != SHT_RELA)
|
|
continue;
|
|
|
|
sec->base = find_section_by_name(elf, sec->name + 5);
|
|
if (!sec->base) {
|
|
WARN("can't find base section for rela section %s",
|
|
sec->name);
|
|
return -1;
|
|
}
|
|
|
|
sec->base->rela = sec;
|
|
|
|
for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
|
|
rela = malloc(sizeof(*rela));
|
|
if (!rela) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
memset(rela, 0, sizeof(*rela));
|
|
|
|
if (!gelf_getrela(sec->data, i, &rela->rela)) {
|
|
WARN_ELF("gelf_getrela");
|
|
return -1;
|
|
}
|
|
|
|
rela->type = GELF_R_TYPE(rela->rela.r_info);
|
|
rela->addend = rela->rela.r_addend;
|
|
rela->offset = rela->rela.r_offset;
|
|
symndx = GELF_R_SYM(rela->rela.r_info);
|
|
rela->sym = find_symbol_by_index(elf, symndx);
|
|
if (!rela->sym) {
|
|
WARN("can't find rela entry symbol %d for %s",
|
|
symndx, sec->name);
|
|
return -1;
|
|
}
|
|
|
|
list_add_tail(&rela->list, &sec->rela_list);
|
|
hash_add(sec->rela_hash, &rela->hash, rela->offset);
|
|
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
struct elf *elf_open(const char *name, int flags)
|
|
{
|
|
struct elf *elf;
|
|
Elf_Cmd cmd;
|
|
|
|
elf_version(EV_CURRENT);
|
|
|
|
elf = malloc(sizeof(*elf));
|
|
if (!elf) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
memset(elf, 0, sizeof(*elf));
|
|
|
|
INIT_LIST_HEAD(&elf->sections);
|
|
|
|
elf->fd = open(name, flags);
|
|
if (elf->fd == -1) {
|
|
fprintf(stderr, "objtool: Can't open '%s': %s\n",
|
|
name, strerror(errno));
|
|
goto err;
|
|
}
|
|
|
|
if ((flags & O_ACCMODE) == O_RDONLY)
|
|
cmd = ELF_C_READ_MMAP;
|
|
else if ((flags & O_ACCMODE) == O_RDWR)
|
|
cmd = ELF_C_RDWR;
|
|
else /* O_WRONLY */
|
|
cmd = ELF_C_WRITE;
|
|
|
|
elf->elf = elf_begin(elf->fd, cmd, NULL);
|
|
if (!elf->elf) {
|
|
WARN_ELF("elf_begin");
|
|
goto err;
|
|
}
|
|
|
|
if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
|
|
WARN_ELF("gelf_getehdr");
|
|
goto err;
|
|
}
|
|
|
|
if (read_sections(elf))
|
|
goto err;
|
|
|
|
if (read_symbols(elf))
|
|
goto err;
|
|
|
|
if (read_relas(elf))
|
|
goto err;
|
|
|
|
return elf;
|
|
|
|
err:
|
|
elf_close(elf);
|
|
return NULL;
|
|
}
|
|
|
|
struct section *elf_create_section(struct elf *elf, const char *name,
|
|
size_t entsize, int nr)
|
|
{
|
|
struct section *sec, *shstrtab;
|
|
size_t size = entsize * nr;
|
|
struct Elf_Scn *s;
|
|
Elf_Data *data;
|
|
|
|
sec = malloc(sizeof(*sec));
|
|
if (!sec) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
memset(sec, 0, sizeof(*sec));
|
|
|
|
INIT_LIST_HEAD(&sec->symbol_list);
|
|
INIT_LIST_HEAD(&sec->rela_list);
|
|
hash_init(sec->rela_hash);
|
|
hash_init(sec->symbol_hash);
|
|
|
|
list_add_tail(&sec->list, &elf->sections);
|
|
|
|
s = elf_newscn(elf->elf);
|
|
if (!s) {
|
|
WARN_ELF("elf_newscn");
|
|
return NULL;
|
|
}
|
|
|
|
sec->name = strdup(name);
|
|
if (!sec->name) {
|
|
perror("strdup");
|
|
return NULL;
|
|
}
|
|
|
|
sec->idx = elf_ndxscn(s);
|
|
sec->len = size;
|
|
sec->changed = true;
|
|
|
|
sec->data = elf_newdata(s);
|
|
if (!sec->data) {
|
|
WARN_ELF("elf_newdata");
|
|
return NULL;
|
|
}
|
|
|
|
sec->data->d_size = size;
|
|
sec->data->d_align = 1;
|
|
|
|
if (size) {
|
|
sec->data->d_buf = malloc(size);
|
|
if (!sec->data->d_buf) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
memset(sec->data->d_buf, 0, size);
|
|
}
|
|
|
|
if (!gelf_getshdr(s, &sec->sh)) {
|
|
WARN_ELF("gelf_getshdr");
|
|
return NULL;
|
|
}
|
|
|
|
sec->sh.sh_size = size;
|
|
sec->sh.sh_entsize = entsize;
|
|
sec->sh.sh_type = SHT_PROGBITS;
|
|
sec->sh.sh_addralign = 1;
|
|
sec->sh.sh_flags = SHF_ALLOC;
|
|
|
|
|
|
/* Add section name to .shstrtab */
|
|
shstrtab = find_section_by_name(elf, ".shstrtab");
|
|
if (!shstrtab) {
|
|
WARN("can't find .shstrtab section");
|
|
return NULL;
|
|
}
|
|
|
|
s = elf_getscn(elf->elf, shstrtab->idx);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return NULL;
|
|
}
|
|
|
|
data = elf_newdata(s);
|
|
if (!data) {
|
|
WARN_ELF("elf_newdata");
|
|
return NULL;
|
|
}
|
|
|
|
data->d_buf = sec->name;
|
|
data->d_size = strlen(name) + 1;
|
|
data->d_align = 1;
|
|
|
|
sec->sh.sh_name = shstrtab->len;
|
|
|
|
shstrtab->len += strlen(name) + 1;
|
|
shstrtab->changed = true;
|
|
|
|
return sec;
|
|
}
|
|
|
|
struct section *elf_create_rela_section(struct elf *elf, struct section *base)
|
|
{
|
|
char *relaname;
|
|
struct section *sec;
|
|
|
|
relaname = malloc(strlen(base->name) + strlen(".rela") + 1);
|
|
if (!relaname) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
strcpy(relaname, ".rela");
|
|
strcat(relaname, base->name);
|
|
|
|
sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0);
|
|
free(relaname);
|
|
if (!sec)
|
|
return NULL;
|
|
|
|
base->rela = sec;
|
|
sec->base = base;
|
|
|
|
sec->sh.sh_type = SHT_RELA;
|
|
sec->sh.sh_addralign = 8;
|
|
sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
|
|
sec->sh.sh_info = base->idx;
|
|
sec->sh.sh_flags = SHF_INFO_LINK;
|
|
|
|
return sec;
|
|
}
|
|
|
|
int elf_rebuild_rela_section(struct section *sec)
|
|
{
|
|
struct rela *rela;
|
|
int nr, idx = 0, size;
|
|
GElf_Rela *relas;
|
|
|
|
nr = 0;
|
|
list_for_each_entry(rela, &sec->rela_list, list)
|
|
nr++;
|
|
|
|
size = nr * sizeof(*relas);
|
|
relas = malloc(size);
|
|
if (!relas) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
|
|
sec->data->d_buf = relas;
|
|
sec->data->d_size = size;
|
|
|
|
sec->sh.sh_size = size;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(rela, &sec->rela_list, list) {
|
|
relas[idx].r_offset = rela->offset;
|
|
relas[idx].r_addend = rela->addend;
|
|
relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type);
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int elf_write(struct elf *elf)
|
|
{
|
|
struct section *sec;
|
|
Elf_Scn *s;
|
|
|
|
/* Update section headers for changed sections: */
|
|
list_for_each_entry(sec, &elf->sections, list) {
|
|
if (sec->changed) {
|
|
s = elf_getscn(elf->elf, sec->idx);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return -1;
|
|
}
|
|
if (!gelf_update_shdr(s, &sec->sh)) {
|
|
WARN_ELF("gelf_update_shdr");
|
|
return -1;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Make sure the new section header entries get updated properly. */
|
|
elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
|
|
|
|
/* Write all changes to the file. */
|
|
if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
|
|
WARN_ELF("elf_update");
|
|
return -1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void elf_close(struct elf *elf)
|
|
{
|
|
struct section *sec, *tmpsec;
|
|
struct symbol *sym, *tmpsym;
|
|
struct rela *rela, *tmprela;
|
|
|
|
if (elf->elf)
|
|
elf_end(elf->elf);
|
|
|
|
if (elf->fd > 0)
|
|
close(elf->fd);
|
|
|
|
list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
|
|
list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
|
|
list_del(&sym->list);
|
|
hash_del(&sym->hash);
|
|
free(sym);
|
|
}
|
|
list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) {
|
|
list_del(&rela->list);
|
|
hash_del(&rela->hash);
|
|
free(rela);
|
|
}
|
|
list_del(&sec->list);
|
|
free(sec);
|
|
}
|
|
|
|
free(elf);
|
|
}
|