]>
git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - tools/objtool/elf.c
2 * elf.c - ELF access library
4 * Adapted from kpatch (https://github.com/dynup/kpatch):
5 * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
6 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version 2
11 * of the License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, see <http://www.gnu.org/licenses/>.
22 #include <sys/types.h>
33 struct section
*find_section_by_name(struct elf
*elf
, const char *name
)
37 list_for_each_entry(sec
, &elf
->sections
, list
)
38 if (!strcmp(sec
->name
, name
))
44 static struct section
*find_section_by_index(struct elf
*elf
,
49 list_for_each_entry(sec
, &elf
->sections
, list
)
56 static struct symbol
*find_symbol_by_index(struct elf
*elf
, unsigned int idx
)
61 list_for_each_entry(sec
, &elf
->sections
, list
)
62 hash_for_each_possible(sec
->symbol_hash
, sym
, hash
, idx
)
69 struct symbol
*find_symbol_by_offset(struct section
*sec
, unsigned long offset
)
73 list_for_each_entry(sym
, &sec
->symbol_list
, list
)
74 if (sym
->type
!= STT_SECTION
&&
75 sym
->offset
== offset
)
81 struct symbol
*find_symbol_containing(struct section
*sec
, unsigned long offset
)
85 list_for_each_entry(sym
, &sec
->symbol_list
, list
)
86 if (sym
->type
!= STT_SECTION
&&
87 offset
>= sym
->offset
&& offset
< sym
->offset
+ sym
->len
)
93 struct rela
*find_rela_by_dest_range(struct section
*sec
, unsigned long offset
,
102 for (o
= offset
; o
< offset
+ len
; o
++)
103 hash_for_each_possible(sec
->rela
->rela_hash
, rela
, hash
, o
)
104 if (rela
->offset
== o
)
110 struct rela
*find_rela_by_dest(struct section
*sec
, unsigned long offset
)
112 return find_rela_by_dest_range(sec
, offset
, 1);
115 struct symbol
*find_containing_func(struct section
*sec
, unsigned long offset
)
119 list_for_each_entry(func
, &sec
->symbol_list
, list
)
120 if (func
->type
== STT_FUNC
&& offset
>= func
->offset
&&
121 offset
< func
->offset
+ func
->len
)
127 static int read_sections(struct elf
*elf
)
131 size_t shstrndx
, sections_nr
;
134 if (elf_getshdrnum(elf
->elf
, §ions_nr
)) {
135 WARN_ELF("elf_getshdrnum");
139 if (elf_getshdrstrndx(elf
->elf
, &shstrndx
)) {
140 WARN_ELF("elf_getshdrstrndx");
144 for (i
= 0; i
< sections_nr
; i
++) {
145 sec
= malloc(sizeof(*sec
));
150 memset(sec
, 0, sizeof(*sec
));
152 INIT_LIST_HEAD(&sec
->symbol_list
);
153 INIT_LIST_HEAD(&sec
->rela_list
);
154 hash_init(sec
->rela_hash
);
155 hash_init(sec
->symbol_hash
);
157 list_add_tail(&sec
->list
, &elf
->sections
);
159 s
= elf_getscn(elf
->elf
, i
);
161 WARN_ELF("elf_getscn");
165 sec
->idx
= elf_ndxscn(s
);
167 if (!gelf_getshdr(s
, &sec
->sh
)) {
168 WARN_ELF("gelf_getshdr");
172 sec
->name
= elf_strptr(elf
->elf
, shstrndx
, sec
->sh
.sh_name
);
174 WARN_ELF("elf_strptr");
178 if (sec
->sh
.sh_size
!= 0) {
179 sec
->data
= elf_getdata(s
, NULL
);
181 WARN_ELF("elf_getdata");
184 if (sec
->data
->d_off
!= 0 ||
185 sec
->data
->d_size
!= sec
->sh
.sh_size
) {
186 WARN("unexpected data attributes for %s",
191 sec
->len
= sec
->sh
.sh_size
;
194 /* sanity check, one more call to elf_nextscn() should return NULL */
195 if (elf_nextscn(elf
->elf
, s
)) {
196 WARN("section entry mismatch");
203 static int read_symbols(struct elf
*elf
)
205 struct section
*symtab
;
207 struct list_head
*entry
, *tmp
;
210 symtab
= find_section_by_name(elf
, ".symtab");
212 WARN("missing symbol table");
216 symbols_nr
= symtab
->sh
.sh_size
/ symtab
->sh
.sh_entsize
;
218 for (i
= 0; i
< symbols_nr
; i
++) {
219 sym
= malloc(sizeof(*sym
));
224 memset(sym
, 0, sizeof(*sym
));
228 if (!gelf_getsym(symtab
->data
, i
, &sym
->sym
)) {
229 WARN_ELF("gelf_getsym");
233 sym
->name
= elf_strptr(elf
->elf
, symtab
->sh
.sh_link
,
236 WARN_ELF("elf_strptr");
240 sym
->type
= GELF_ST_TYPE(sym
->sym
.st_info
);
241 sym
->bind
= GELF_ST_BIND(sym
->sym
.st_info
);
243 if (sym
->sym
.st_shndx
> SHN_UNDEF
&&
244 sym
->sym
.st_shndx
< SHN_LORESERVE
) {
245 sym
->sec
= find_section_by_index(elf
,
248 WARN("couldn't find section for symbol %s",
252 if (sym
->type
== STT_SECTION
) {
253 sym
->name
= sym
->sec
->name
;
257 sym
->sec
= find_section_by_index(elf
, 0);
259 sym
->offset
= sym
->sym
.st_value
;
260 sym
->len
= sym
->sym
.st_size
;
262 /* sorted insert into a per-section list */
263 entry
= &sym
->sec
->symbol_list
;
264 list_for_each_prev(tmp
, &sym
->sec
->symbol_list
) {
267 s
= list_entry(tmp
, struct symbol
, list
);
269 if (sym
->offset
> s
->offset
) {
274 if (sym
->offset
== s
->offset
&& sym
->len
>= s
->len
) {
279 list_add(&sym
->list
, entry
);
280 hash_add(sym
->sec
->symbol_hash
, &sym
->hash
, sym
->idx
);
290 static int read_relas(struct elf
*elf
)
297 list_for_each_entry(sec
, &elf
->sections
, list
) {
298 if (sec
->sh
.sh_type
!= SHT_RELA
)
301 sec
->base
= find_section_by_name(elf
, sec
->name
+ 5);
303 WARN("can't find base section for rela section %s",
308 sec
->base
->rela
= sec
;
310 for (i
= 0; i
< sec
->sh
.sh_size
/ sec
->sh
.sh_entsize
; i
++) {
311 rela
= malloc(sizeof(*rela
));
316 memset(rela
, 0, sizeof(*rela
));
318 if (!gelf_getrela(sec
->data
, i
, &rela
->rela
)) {
319 WARN_ELF("gelf_getrela");
323 rela
->type
= GELF_R_TYPE(rela
->rela
.r_info
);
324 rela
->addend
= rela
->rela
.r_addend
;
325 rela
->offset
= rela
->rela
.r_offset
;
326 symndx
= GELF_R_SYM(rela
->rela
.r_info
);
327 rela
->sym
= find_symbol_by_index(elf
, symndx
);
329 WARN("can't find rela entry symbol %d for %s",
334 list_add_tail(&rela
->list
, &sec
->rela_list
);
335 hash_add(sec
->rela_hash
, &rela
->hash
, rela
->offset
);
343 struct elf
*elf_open(const char *name
, int flags
)
348 elf_version(EV_CURRENT
);
350 elf
= malloc(sizeof(*elf
));
355 memset(elf
, 0, sizeof(*elf
));
357 INIT_LIST_HEAD(&elf
->sections
);
359 elf
->fd
= open(name
, flags
);
365 if ((flags
& O_ACCMODE
) == O_RDONLY
)
366 cmd
= ELF_C_READ_MMAP
;
367 else if ((flags
& O_ACCMODE
) == O_RDWR
)
372 elf
->elf
= elf_begin(elf
->fd
, cmd
, NULL
);
374 WARN_ELF("elf_begin");
378 if (!gelf_getehdr(elf
->elf
, &elf
->ehdr
)) {
379 WARN_ELF("gelf_getehdr");
383 if (read_sections(elf
))
386 if (read_symbols(elf
))
399 struct section
*elf_create_section(struct elf
*elf
, const char *name
,
400 size_t entsize
, int nr
)
402 struct section
*sec
, *shstrtab
;
403 size_t size
= entsize
* nr
;
407 sec
= malloc(sizeof(*sec
));
412 memset(sec
, 0, sizeof(*sec
));
414 INIT_LIST_HEAD(&sec
->symbol_list
);
415 INIT_LIST_HEAD(&sec
->rela_list
);
416 hash_init(sec
->rela_hash
);
417 hash_init(sec
->symbol_hash
);
419 list_add_tail(&sec
->list
, &elf
->sections
);
421 s
= elf_newscn(elf
->elf
);
423 WARN_ELF("elf_newscn");
427 sec
->name
= strdup(name
);
433 sec
->idx
= elf_ndxscn(s
);
437 sec
->data
= elf_newdata(s
);
439 WARN_ELF("elf_newdata");
443 sec
->data
->d_size
= size
;
444 sec
->data
->d_align
= 1;
447 sec
->data
->d_buf
= malloc(size
);
448 if (!sec
->data
->d_buf
) {
452 memset(sec
->data
->d_buf
, 0, size
);
455 if (!gelf_getshdr(s
, &sec
->sh
)) {
456 WARN_ELF("gelf_getshdr");
460 sec
->sh
.sh_size
= size
;
461 sec
->sh
.sh_entsize
= entsize
;
462 sec
->sh
.sh_type
= SHT_PROGBITS
;
463 sec
->sh
.sh_addralign
= 1;
464 sec
->sh
.sh_flags
= SHF_ALLOC
;
467 /* Add section name to .shstrtab */
468 shstrtab
= find_section_by_name(elf
, ".shstrtab");
470 WARN("can't find .shstrtab section");
474 s
= elf_getscn(elf
->elf
, shstrtab
->idx
);
476 WARN_ELF("elf_getscn");
480 data
= elf_newdata(s
);
482 WARN_ELF("elf_newdata");
486 data
->d_buf
= sec
->name
;
487 data
->d_size
= strlen(name
) + 1;
490 sec
->sh
.sh_name
= shstrtab
->len
;
492 shstrtab
->len
+= strlen(name
) + 1;
493 shstrtab
->changed
= true;
498 struct section
*elf_create_rela_section(struct elf
*elf
, struct section
*base
)
503 relaname
= malloc(strlen(base
->name
) + strlen(".rela") + 1);
508 strcpy(relaname
, ".rela");
509 strcat(relaname
, base
->name
);
511 sec
= elf_create_section(elf
, relaname
, sizeof(GElf_Rela
), 0);
519 sec
->sh
.sh_type
= SHT_RELA
;
520 sec
->sh
.sh_addralign
= 8;
521 sec
->sh
.sh_link
= find_section_by_name(elf
, ".symtab")->idx
;
522 sec
->sh
.sh_info
= base
->idx
;
523 sec
->sh
.sh_flags
= SHF_INFO_LINK
;
528 int elf_rebuild_rela_section(struct section
*sec
)
531 int nr
, idx
= 0, size
;
535 list_for_each_entry(rela
, &sec
->rela_list
, list
)
538 size
= nr
* sizeof(*relas
);
539 relas
= malloc(size
);
545 sec
->data
->d_buf
= relas
;
546 sec
->data
->d_size
= size
;
548 sec
->sh
.sh_size
= size
;
551 list_for_each_entry(rela
, &sec
->rela_list
, list
) {
552 relas
[idx
].r_offset
= rela
->offset
;
553 relas
[idx
].r_addend
= rela
->addend
;
554 relas
[idx
].r_info
= GELF_R_INFO(rela
->sym
->idx
, rela
->type
);
561 int elf_write(struct elf
*elf
)
566 /* Update section headers for changed sections: */
567 list_for_each_entry(sec
, &elf
->sections
, list
) {
569 s
= elf_getscn(elf
->elf
, sec
->idx
);
571 WARN_ELF("elf_getscn");
574 if (!gelf_update_shdr(s
, &sec
->sh
)) {
575 WARN_ELF("gelf_update_shdr");
581 /* Make sure the new section header entries get updated properly. */
582 elf_flagelf(elf
->elf
, ELF_C_SET
, ELF_F_DIRTY
);
584 /* Write all changes to the file. */
585 if (elf_update(elf
->elf
, ELF_C_WRITE
) < 0) {
586 WARN_ELF("elf_update");
593 void elf_close(struct elf
*elf
)
595 struct section
*sec
, *tmpsec
;
596 struct symbol
*sym
, *tmpsym
;
597 struct rela
*rela
, *tmprela
;
605 list_for_each_entry_safe(sec
, tmpsec
, &elf
->sections
, list
) {
606 list_for_each_entry_safe(sym
, tmpsym
, &sec
->symbol_list
, list
) {
607 list_del(&sym
->list
);
608 hash_del(&sym
->hash
);
611 list_for_each_entry_safe(rela
, tmprela
, &sec
->rela_list
, list
) {
612 list_del(&rela
->list
);
613 hash_del(&rela
->hash
);
616 list_del(&sec
->list
);