1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * elf.c - ELF access library
5 * Adapted from kpatch (https://github.com/dynup/kpatch):
6 * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
7 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
10 #include <sys/types.h>
19 #include <objtool/builtin.h>
21 #include <objtool/elf.h>
22 #include <objtool/warn.h>
24 #define MAX_NAME_LEN 128
26 static inline u32 str_hash(const char *str)
28 return jhash(str, strlen(str), 0);
31 #define __elf_table(name) (elf->name##_hash)
32 #define __elf_bits(name) (elf->name##_bits)
34 #define elf_hash_add(name, node, key) \
35 hlist_add_head(node, &__elf_table(name)[hash_min(key, __elf_bits(name))])
37 #define elf_hash_for_each_possible(name, obj, member, key) \
38 hlist_for_each_entry(obj, &__elf_table(name)[hash_min(key, __elf_bits(name))], member)
40 #define elf_alloc_hash(name, size) \
42 __elf_bits(name) = max(10, ilog2(size)); \
43 __elf_table(name) = mmap(NULL, sizeof(struct hlist_head) << __elf_bits(name), \
44 PROT_READ|PROT_WRITE, \
45 MAP_PRIVATE|MAP_ANON, -1, 0); \
46 if (__elf_table(name) == (void *)-1L) { \
47 WARN("mmap fail " #name); \
48 __elf_table(name) = NULL; \
53 static bool symbol_to_offset(struct rb_node *a, const struct rb_node *b)
55 struct symbol *sa = rb_entry(a, struct symbol, node);
56 struct symbol *sb = rb_entry(b, struct symbol, node);
58 if (sa->offset < sb->offset)
60 if (sa->offset > sb->offset)
63 if (sa->len < sb->len)
65 if (sa->len > sb->len)
73 static int symbol_by_offset(const void *key, const struct rb_node *node)
75 const struct symbol *s = rb_entry(node, struct symbol, node);
76 const unsigned long *o = key;
80 if (*o >= s->offset + s->len)
88 const struct symbol *sym;
92 * Find !section symbol where @offset is after it.
94 static int symbol_hole_by_offset(const void *key, const struct rb_node *node)
96 const struct symbol *s = rb_entry(node, struct symbol, node);
97 struct symbol_hole *sh = (void *)key;
99 if (sh->key < s->offset)
102 if (sh->key >= s->offset + s->len) {
103 if (s->type != STT_SECTION)
111 struct section *find_section_by_name(const struct elf *elf, const char *name)
115 elf_hash_for_each_possible(section_name, sec, name_hash, str_hash(name)) {
116 if (!strcmp(sec->name, name))
123 static struct section *find_section_by_index(struct elf *elf,
128 elf_hash_for_each_possible(section, sec, hash, idx) {
136 static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
140 elf_hash_for_each_possible(symbol, sym, hash, idx) {
148 struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
150 struct rb_node *node;
152 rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
153 struct symbol *s = rb_entry(node, struct symbol, node);
155 if (s->offset == offset && s->type != STT_SECTION)
162 struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
164 struct rb_node *node;
166 rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
167 struct symbol *s = rb_entry(node, struct symbol, node);
169 if (s->offset == offset && s->type == STT_FUNC)
176 struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
178 struct rb_node *node;
180 rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
181 struct symbol *s = rb_entry(node, struct symbol, node);
183 if (s->type != STT_SECTION)
191 * Returns size of hole starting at @offset.
193 int find_symbol_hole_containing(const struct section *sec, unsigned long offset)
195 struct symbol_hole hole = {
203 * Find the rightmost symbol for which @offset is after it.
205 n = rb_find(&hole, &sec->symbol_tree, symbol_hole_by_offset);
207 /* found a symbol that contains @offset */
209 return 0; /* not a hole */
211 /* didn't find a symbol for which @offset is after it */
213 return 0; /* not a hole */
215 /* @offset >= sym->offset + sym->len, find symbol after it */
216 n = rb_next(&hole.sym->node);
218 return -1; /* until end of address space */
220 /* hole until start of next symbol */
221 s = rb_entry(n, struct symbol, node);
222 return s->offset - offset;
225 struct symbol *find_func_containing(struct section *sec, unsigned long offset)
227 struct rb_node *node;
229 rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
230 struct symbol *s = rb_entry(node, struct symbol, node);
232 if (s->type == STT_FUNC)
239 struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)
243 elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
244 if (!strcmp(sym->name, name))
251 struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
252 unsigned long offset, unsigned int len)
254 struct reloc *reloc, *r = NULL;
262 for_offset_range(o, offset, offset + len) {
263 elf_hash_for_each_possible(reloc, reloc, hash,
264 sec_offset_hash(sec, o)) {
265 if (reloc->sec != sec)
268 if (reloc->offset >= offset && reloc->offset < offset + len) {
269 if (!r || reloc->offset < r->offset)
280 struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset)
282 return find_reloc_by_dest_range(elf, sec, offset, 1);
285 static int read_sections(struct elf *elf)
289 size_t shstrndx, sections_nr;
292 if (elf_getshdrnum(elf->elf, §ions_nr)) {
293 WARN_ELF("elf_getshdrnum");
297 if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
298 WARN_ELF("elf_getshdrstrndx");
302 if (!elf_alloc_hash(section, sections_nr) ||
303 !elf_alloc_hash(section_name, sections_nr))
306 for (i = 0; i < sections_nr; i++) {
307 sec = malloc(sizeof(*sec));
312 memset(sec, 0, sizeof(*sec));
314 INIT_LIST_HEAD(&sec->symbol_list);
315 INIT_LIST_HEAD(&sec->reloc_list);
317 s = elf_getscn(elf->elf, i);
319 WARN_ELF("elf_getscn");
323 sec->idx = elf_ndxscn(s);
325 if (!gelf_getshdr(s, &sec->sh)) {
326 WARN_ELF("gelf_getshdr");
330 sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
332 WARN_ELF("elf_strptr");
336 if (sec->sh.sh_size != 0) {
337 sec->data = elf_getdata(s, NULL);
339 WARN_ELF("elf_getdata");
342 if (sec->data->d_off != 0 ||
343 sec->data->d_size != sec->sh.sh_size) {
344 WARN("unexpected data attributes for %s",
350 if (sec->sh.sh_flags & SHF_EXECINSTR)
351 elf->text_size += sec->sh.sh_size;
353 list_add_tail(&sec->list, &elf->sections);
354 elf_hash_add(section, &sec->hash, sec->idx);
355 elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
359 printf("nr_sections: %lu\n", (unsigned long)sections_nr);
360 printf("section_bits: %d\n", elf->section_bits);
363 /* sanity check, one more call to elf_nextscn() should return NULL */
364 if (elf_nextscn(elf->elf, s)) {
365 WARN("section entry mismatch");
372 static void elf_add_symbol(struct elf *elf, struct symbol *sym)
374 struct list_head *entry;
375 struct rb_node *pnode;
377 INIT_LIST_HEAD(&sym->pv_target);
380 sym->type = GELF_ST_TYPE(sym->sym.st_info);
381 sym->bind = GELF_ST_BIND(sym->sym.st_info);
383 if (sym->type == STT_FILE)
386 sym->offset = sym->sym.st_value;
387 sym->len = sym->sym.st_size;
389 rb_add(&sym->node, &sym->sec->symbol_tree, symbol_to_offset);
390 pnode = rb_prev(&sym->node);
392 entry = &rb_entry(pnode, struct symbol, node)->list;
394 entry = &sym->sec->symbol_list;
395 list_add(&sym->list, entry);
396 elf_hash_add(symbol, &sym->hash, sym->idx);
397 elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
400 * Don't store empty STT_NOTYPE symbols in the rbtree. They
401 * can exist within a function, confusing the sorting.
404 rb_erase(&sym->node, &sym->sec->symbol_tree);
407 static int read_symbols(struct elf *elf)
409 struct section *symtab, *symtab_shndx, *sec;
410 struct symbol *sym, *pfunc;
413 Elf_Data *shndx_data = NULL;
416 symtab = find_section_by_name(elf, ".symtab");
418 symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
420 shndx_data = symtab_shndx->data;
422 symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
425 * A missing symbol table is actually possible if it's an empty
426 * .o file. This can happen for thunk_64.o. Make sure to at
427 * least allocate the symbol hash tables so we can do symbol
428 * lookups without crashing.
433 if (!elf_alloc_hash(symbol, symbols_nr) ||
434 !elf_alloc_hash(symbol_name, symbols_nr))
437 for (i = 0; i < symbols_nr; i++) {
438 sym = malloc(sizeof(*sym));
443 memset(sym, 0, sizeof(*sym));
447 if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
449 WARN_ELF("gelf_getsymshndx");
453 sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
456 WARN_ELF("elf_strptr");
460 if ((sym->sym.st_shndx > SHN_UNDEF &&
461 sym->sym.st_shndx < SHN_LORESERVE) ||
462 (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) {
463 if (sym->sym.st_shndx != SHN_XINDEX)
464 shndx = sym->sym.st_shndx;
466 sym->sec = find_section_by_index(elf, shndx);
468 WARN("couldn't find section for symbol %s",
472 if (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) {
473 sym->name = sym->sec->name;
477 sym->sec = find_section_by_index(elf, 0);
479 elf_add_symbol(elf, sym);
483 printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
484 printf("symbol_bits: %d\n", elf->symbol_bits);
487 /* Create parent/child links for any cold subfunctions */
488 list_for_each_entry(sec, &elf->sections, list) {
489 list_for_each_entry(sym, &sec->symbol_list, list) {
490 char pname[MAX_NAME_LEN + 1];
492 if (sym->type != STT_FUNC)
495 if (sym->pfunc == NULL)
498 if (sym->cfunc == NULL)
501 coldstr = strstr(sym->name, ".cold");
505 pnamelen = coldstr - sym->name;
506 if (pnamelen > MAX_NAME_LEN) {
507 WARN("%s(): parent function name exceeds maximum length of %d characters",
508 sym->name, MAX_NAME_LEN);
512 strncpy(pname, sym->name, pnamelen);
513 pname[pnamelen] = '\0';
514 pfunc = find_symbol_by_name(elf, pname);
517 WARN("%s(): can't find parent function",
526 * Unfortunately, -fnoreorder-functions puts the child
527 * inside the parent. Remove the overlap so we can
528 * have sane assumptions.
530 * Note that pfunc->len now no longer matches
531 * pfunc->sym.st_size.
533 if (sym->sec == pfunc->sec &&
534 sym->offset >= pfunc->offset &&
535 sym->offset + sym->len == pfunc->offset + pfunc->len) {
536 pfunc->len -= sym->len;
548 static struct section *elf_create_reloc_section(struct elf *elf,
549 struct section *base,
552 int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
553 unsigned int type, struct symbol *sym, s64 addend)
557 if (!sec->reloc && !elf_create_reloc_section(elf, sec, SHT_RELA))
560 reloc = malloc(sizeof(*reloc));
565 memset(reloc, 0, sizeof(*reloc));
567 reloc->sec = sec->reloc;
568 reloc->offset = offset;
571 reloc->addend = addend;
573 list_add_tail(&reloc->list, &sec->reloc->reloc_list);
574 elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
576 sec->reloc->sh.sh_size += sec->reloc->sh.sh_entsize;
577 sec->reloc->changed = true;
583 * Ensure that any reloc section containing references to @sym is marked
584 * changed such that it will get re-generated in elf_rebuild_reloc_sections()
585 * with the new symbol index.
587 static void elf_dirty_reloc_sym(struct elf *elf, struct symbol *sym)
591 list_for_each_entry(sec, &elf->sections, list) {
597 list_for_each_entry(reloc, &sec->reloc_list, list) {
598 if (reloc->sym == sym) {
607 * The libelf API is terrible; gelf_update_sym*() takes a data block relative
608 * index value, *NOT* the symbol index. As such, iterate the data blocks and
609 * adjust index until it fits.
611 * If no data block is found, allow adding a new data block provided the index
612 * is only one past the end.
614 static int elf_update_symbol(struct elf *elf, struct section *symtab,
615 struct section *symtab_shndx, struct symbol *sym)
617 Elf32_Word shndx = sym->sec ? sym->sec->idx : SHN_UNDEF;
618 Elf_Data *symtab_data = NULL, *shndx_data = NULL;
619 Elf64_Xword entsize = symtab->sh.sh_entsize;
620 int max_idx, idx = sym->idx;
621 Elf_Scn *s, *t = NULL;
622 bool is_special_shndx = sym->sym.st_shndx >= SHN_LORESERVE &&
623 sym->sym.st_shndx != SHN_XINDEX;
625 if (is_special_shndx)
626 shndx = sym->sym.st_shndx;
628 s = elf_getscn(elf->elf, symtab->idx);
630 WARN_ELF("elf_getscn");
635 t = elf_getscn(elf->elf, symtab_shndx->idx);
637 WARN_ELF("elf_getscn");
643 /* get next data descriptor for the relevant sections */
644 symtab_data = elf_getdata(s, symtab_data);
646 shndx_data = elf_getdata(t, shndx_data);
653 /* we don't do holes in symbol tables */
654 WARN("index out of range");
658 /* if @idx == 0, it's the next contiguous entry, create it */
659 symtab_data = elf_newdata(s);
661 shndx_data = elf_newdata(t);
663 buf = calloc(1, entsize);
669 symtab_data->d_buf = buf;
670 symtab_data->d_size = entsize;
671 symtab_data->d_align = 1;
672 symtab_data->d_type = ELF_T_SYM;
674 symtab->sh.sh_size += entsize;
675 symtab->changed = true;
678 shndx_data->d_buf = &sym->sec->idx;
679 shndx_data->d_size = sizeof(Elf32_Word);
680 shndx_data->d_align = sizeof(Elf32_Word);
681 shndx_data->d_type = ELF_T_WORD;
683 symtab_shndx->sh.sh_size += sizeof(Elf32_Word);
684 symtab_shndx->changed = true;
690 /* empty blocks should not happen */
691 if (!symtab_data->d_size) {
692 WARN("zero size data");
696 /* is this the right block? */
697 max_idx = symtab_data->d_size / entsize;
701 /* adjust index and try again */
705 /* something went side-ways */
707 WARN("negative index");
711 /* setup extended section index magic and write the symbol */
712 if ((shndx >= SHN_UNDEF && shndx < SHN_LORESERVE) || is_special_shndx) {
713 sym->sym.st_shndx = shndx;
717 sym->sym.st_shndx = SHN_XINDEX;
719 WARN("no .symtab_shndx");
724 if (!gelf_update_symshndx(symtab_data, shndx_data, idx, &sym->sym, shndx)) {
725 WARN_ELF("gelf_update_symshndx");
732 static struct symbol *
733 elf_create_section_symbol(struct elf *elf, struct section *sec)
735 struct section *symtab, *symtab_shndx;
736 Elf32_Word first_non_local, new_idx;
737 struct symbol *sym, *old;
739 symtab = find_section_by_name(elf, ".symtab");
741 symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
747 sym = calloc(1, sizeof(*sym));
753 sym->name = sec->name;
757 sym->sym.st_info = GELF_ST_INFO(STB_LOCAL, STT_SECTION);
763 * Move the first global symbol, as per sh_info, into a new, higher
764 * symbol index. This fees up a spot for a new local symbol.
766 first_non_local = symtab->sh.sh_info;
767 new_idx = symtab->sh.sh_size / symtab->sh.sh_entsize;
768 old = find_symbol_by_index(elf, first_non_local);
772 hlist_del(&old->hash);
773 elf_hash_add(symbol, &old->hash, old->idx);
775 elf_dirty_reloc_sym(elf, old);
777 if (elf_update_symbol(elf, symtab, symtab_shndx, old)) {
778 WARN("elf_update_symbol move");
782 new_idx = first_non_local;
786 if (elf_update_symbol(elf, symtab, symtab_shndx, sym)) {
787 WARN("elf_update_symbol");
792 * Either way, we added a LOCAL symbol.
794 symtab->sh.sh_info += 1;
796 elf_add_symbol(elf, sym);
801 int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
802 unsigned long offset, unsigned int type,
803 struct section *insn_sec, unsigned long insn_off)
805 struct symbol *sym = insn_sec->sym;
806 int addend = insn_off;
810 * Due to how weak functions work, we must use section based
811 * relocations. Symbol based relocations would result in the
812 * weak and non-weak function annotations being overlaid on the
813 * non-weak function after linking.
815 sym = elf_create_section_symbol(elf, insn_sec);
822 return elf_add_reloc(elf, sec, offset, type, sym, addend);
825 static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
827 if (!gelf_getrel(sec->data, i, &reloc->rel)) {
828 WARN_ELF("gelf_getrel");
831 reloc->type = GELF_R_TYPE(reloc->rel.r_info);
833 reloc->offset = reloc->rel.r_offset;
834 *symndx = GELF_R_SYM(reloc->rel.r_info);
838 static int read_rela_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
840 if (!gelf_getrela(sec->data, i, &reloc->rela)) {
841 WARN_ELF("gelf_getrela");
844 reloc->type = GELF_R_TYPE(reloc->rela.r_info);
845 reloc->addend = reloc->rela.r_addend;
846 reloc->offset = reloc->rela.r_offset;
847 *symndx = GELF_R_SYM(reloc->rela.r_info);
851 static int read_relocs(struct elf *elf)
857 unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0;
859 if (!elf_alloc_hash(reloc, elf->text_size / 16))
862 list_for_each_entry(sec, &elf->sections, list) {
863 if ((sec->sh.sh_type != SHT_RELA) &&
864 (sec->sh.sh_type != SHT_REL))
867 sec->base = find_section_by_index(elf, sec->sh.sh_info);
869 WARN("can't find base section for reloc section %s",
874 sec->base->reloc = sec;
877 for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
878 reloc = malloc(sizeof(*reloc));
883 memset(reloc, 0, sizeof(*reloc));
884 switch (sec->sh.sh_type) {
886 if (read_rel_reloc(sec, i, reloc, &symndx))
890 if (read_rela_reloc(sec, i, reloc, &symndx))
898 reloc->sym = find_symbol_by_index(elf, symndx);
900 WARN("can't find reloc entry symbol %d for %s",
905 list_add_tail(&reloc->list, &sec->reloc_list);
906 elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
910 max_reloc = max(max_reloc, nr_reloc);
911 tot_reloc += nr_reloc;
915 printf("max_reloc: %lu\n", max_reloc);
916 printf("tot_reloc: %lu\n", tot_reloc);
917 printf("reloc_bits: %d\n", elf->reloc_bits);
923 struct elf *elf_open_read(const char *name, int flags)
928 elf_version(EV_CURRENT);
930 elf = malloc(sizeof(*elf));
935 memset(elf, 0, offsetof(struct elf, sections));
937 INIT_LIST_HEAD(&elf->sections);
939 elf->fd = open(name, flags);
941 fprintf(stderr, "objtool: Can't open '%s': %s\n",
942 name, strerror(errno));
946 if ((flags & O_ACCMODE) == O_RDONLY)
947 cmd = ELF_C_READ_MMAP;
948 else if ((flags & O_ACCMODE) == O_RDWR)
953 elf->elf = elf_begin(elf->fd, cmd, NULL);
955 WARN_ELF("elf_begin");
959 if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
960 WARN_ELF("gelf_getehdr");
964 if (read_sections(elf))
967 if (read_symbols(elf))
970 if (read_relocs(elf))
980 static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
987 strtab = find_section_by_name(elf, ".strtab");
989 WARN("can't find .strtab section");
993 s = elf_getscn(elf->elf, strtab->idx);
995 WARN_ELF("elf_getscn");
999 data = elf_newdata(s);
1001 WARN_ELF("elf_newdata");
1006 data->d_size = strlen(str) + 1;
1009 len = strtab->sh.sh_size;
1010 strtab->sh.sh_size += data->d_size;
1011 strtab->changed = true;
1016 struct section *elf_create_section(struct elf *elf, const char *name,
1017 unsigned int sh_flags, size_t entsize, int nr)
1019 struct section *sec, *shstrtab;
1020 size_t size = entsize * nr;
1023 sec = malloc(sizeof(*sec));
1028 memset(sec, 0, sizeof(*sec));
1030 INIT_LIST_HEAD(&sec->symbol_list);
1031 INIT_LIST_HEAD(&sec->reloc_list);
1033 s = elf_newscn(elf->elf);
1035 WARN_ELF("elf_newscn");
1039 sec->name = strdup(name);
1045 sec->idx = elf_ndxscn(s);
1046 sec->changed = true;
1048 sec->data = elf_newdata(s);
1050 WARN_ELF("elf_newdata");
1054 sec->data->d_size = size;
1055 sec->data->d_align = 1;
1058 sec->data->d_buf = malloc(size);
1059 if (!sec->data->d_buf) {
1063 memset(sec->data->d_buf, 0, size);
1066 if (!gelf_getshdr(s, &sec->sh)) {
1067 WARN_ELF("gelf_getshdr");
1071 sec->sh.sh_size = size;
1072 sec->sh.sh_entsize = entsize;
1073 sec->sh.sh_type = SHT_PROGBITS;
1074 sec->sh.sh_addralign = 1;
1075 sec->sh.sh_flags = SHF_ALLOC | sh_flags;
1077 /* Add section name to .shstrtab (or .strtab for Clang) */
1078 shstrtab = find_section_by_name(elf, ".shstrtab");
1080 shstrtab = find_section_by_name(elf, ".strtab");
1082 WARN("can't find .shstrtab or .strtab section");
1085 sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
1086 if (sec->sh.sh_name == -1)
1089 list_add_tail(&sec->list, &elf->sections);
1090 elf_hash_add(section, &sec->hash, sec->idx);
1091 elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
1093 elf->changed = true;
1098 static struct section *elf_create_rel_reloc_section(struct elf *elf, struct section *base)
1101 struct section *sec;
1103 relocname = malloc(strlen(base->name) + strlen(".rel") + 1);
1108 strcpy(relocname, ".rel");
1109 strcat(relocname, base->name);
1111 sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rel), 0);
1119 sec->sh.sh_type = SHT_REL;
1120 sec->sh.sh_addralign = 8;
1121 sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
1122 sec->sh.sh_info = base->idx;
1123 sec->sh.sh_flags = SHF_INFO_LINK;
1128 static struct section *elf_create_rela_reloc_section(struct elf *elf, struct section *base)
1131 struct section *sec;
1133 relocname = malloc(strlen(base->name) + strlen(".rela") + 1);
1138 strcpy(relocname, ".rela");
1139 strcat(relocname, base->name);
1141 sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rela), 0);
1149 sec->sh.sh_type = SHT_RELA;
1150 sec->sh.sh_addralign = 8;
1151 sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
1152 sec->sh.sh_info = base->idx;
1153 sec->sh.sh_flags = SHF_INFO_LINK;
1158 static struct section *elf_create_reloc_section(struct elf *elf,
1159 struct section *base,
1163 case SHT_REL: return elf_create_rel_reloc_section(elf, base);
1164 case SHT_RELA: return elf_create_rela_reloc_section(elf, base);
1165 default: return NULL;
1169 static int elf_rebuild_rel_reloc_section(struct section *sec)
1171 struct reloc *reloc;
1175 /* Allocate a buffer for relocations */
1176 buf = malloc(sec->sh.sh_size);
1182 sec->data->d_buf = buf;
1183 sec->data->d_size = sec->sh.sh_size;
1184 sec->data->d_type = ELF_T_REL;
1187 list_for_each_entry(reloc, &sec->reloc_list, list) {
1188 reloc->rel.r_offset = reloc->offset;
1189 reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
1190 if (!gelf_update_rel(sec->data, idx, &reloc->rel)) {
1191 WARN_ELF("gelf_update_rel");
1200 static int elf_rebuild_rela_reloc_section(struct section *sec)
1202 struct reloc *reloc;
1206 /* Allocate a buffer for relocations with addends */
1207 buf = malloc(sec->sh.sh_size);
1213 sec->data->d_buf = buf;
1214 sec->data->d_size = sec->sh.sh_size;
1215 sec->data->d_type = ELF_T_RELA;
1218 list_for_each_entry(reloc, &sec->reloc_list, list) {
1219 reloc->rela.r_offset = reloc->offset;
1220 reloc->rela.r_addend = reloc->addend;
1221 reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
1222 if (!gelf_update_rela(sec->data, idx, &reloc->rela)) {
1223 WARN_ELF("gelf_update_rela");
1232 static int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
1234 switch (sec->sh.sh_type) {
1235 case SHT_REL: return elf_rebuild_rel_reloc_section(sec);
1236 case SHT_RELA: return elf_rebuild_rela_reloc_section(sec);
1241 int elf_write_insn(struct elf *elf, struct section *sec,
1242 unsigned long offset, unsigned int len,
1245 Elf_Data *data = sec->data;
1247 if (data->d_type != ELF_T_BYTE || data->d_off) {
1248 WARN("write to unexpected data for section: %s", sec->name);
1252 memcpy(data->d_buf + offset, insn, len);
1253 elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
1255 elf->changed = true;
1260 int elf_write_reloc(struct elf *elf, struct reloc *reloc)
1262 struct section *sec = reloc->sec;
1264 if (sec->sh.sh_type == SHT_REL) {
1265 reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
1266 reloc->rel.r_offset = reloc->offset;
1268 if (!gelf_update_rel(sec->data, reloc->idx, &reloc->rel)) {
1269 WARN_ELF("gelf_update_rel");
1273 reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
1274 reloc->rela.r_addend = reloc->addend;
1275 reloc->rela.r_offset = reloc->offset;
1277 if (!gelf_update_rela(sec->data, reloc->idx, &reloc->rela)) {
1278 WARN_ELF("gelf_update_rela");
1283 elf->changed = true;
1288 int elf_write(struct elf *elf)
1290 struct section *sec;
1296 /* Update changed relocation sections and section headers: */
1297 list_for_each_entry(sec, &elf->sections, list) {
1299 s = elf_getscn(elf->elf, sec->idx);
1301 WARN_ELF("elf_getscn");
1304 if (!gelf_update_shdr(s, &sec->sh)) {
1305 WARN_ELF("gelf_update_shdr");
1310 elf_rebuild_reloc_section(elf, sec)) {
1311 WARN("elf_rebuild_reloc_section");
1315 sec->changed = false;
1316 elf->changed = true;
1320 /* Make sure the new section header entries get updated properly. */
1321 elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
1323 /* Write all changes to the file. */
1324 if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
1325 WARN_ELF("elf_update");
1329 elf->changed = false;
1334 void elf_close(struct elf *elf)
1336 struct section *sec, *tmpsec;
1337 struct symbol *sym, *tmpsym;
1338 struct reloc *reloc, *tmpreloc;
1346 list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
1347 list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
1348 list_del(&sym->list);
1349 hash_del(&sym->hash);
1352 list_for_each_entry_safe(reloc, tmpreloc, &sec->reloc_list, list) {
1353 list_del(&reloc->list);
1354 hash_del(&reloc->hash);
1357 list_del(&sec->list);