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)
86 struct section *find_section_by_name(const struct elf *elf, const char *name)
90 elf_hash_for_each_possible(section_name, sec, name_hash, str_hash(name)) {
91 if (!strcmp(sec->name, name))
98 static struct section *find_section_by_index(struct elf *elf,
103 elf_hash_for_each_possible(section, sec, hash, idx) {
111 static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
115 elf_hash_for_each_possible(symbol, sym, hash, idx) {
123 struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
125 struct rb_node *node;
127 rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
128 struct symbol *s = rb_entry(node, struct symbol, node);
130 if (s->offset == offset && s->type != STT_SECTION)
137 struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
139 struct rb_node *node;
141 rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
142 struct symbol *s = rb_entry(node, struct symbol, node);
144 if (s->offset == offset && s->type == STT_FUNC)
151 struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
153 struct rb_node *node;
155 rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
156 struct symbol *s = rb_entry(node, struct symbol, node);
158 if (s->type != STT_SECTION)
165 struct symbol *find_func_containing(struct section *sec, unsigned long offset)
167 struct rb_node *node;
169 rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
170 struct symbol *s = rb_entry(node, struct symbol, node);
172 if (s->type == STT_FUNC)
179 struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)
183 elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
184 if (!strcmp(sym->name, name))
191 struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
192 unsigned long offset, unsigned int len)
194 struct reloc *reloc, *r = NULL;
202 for_offset_range(o, offset, offset + len) {
203 elf_hash_for_each_possible(reloc, reloc, hash,
204 sec_offset_hash(sec, o)) {
205 if (reloc->sec != sec)
208 if (reloc->offset >= offset && reloc->offset < offset + len) {
209 if (!r || reloc->offset < r->offset)
220 struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset)
222 return find_reloc_by_dest_range(elf, sec, offset, 1);
225 static int read_sections(struct elf *elf)
229 size_t shstrndx, sections_nr;
232 if (elf_getshdrnum(elf->elf, §ions_nr)) {
233 WARN_ELF("elf_getshdrnum");
237 if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
238 WARN_ELF("elf_getshdrstrndx");
242 if (!elf_alloc_hash(section, sections_nr) ||
243 !elf_alloc_hash(section_name, sections_nr))
246 for (i = 0; i < sections_nr; i++) {
247 sec = malloc(sizeof(*sec));
252 memset(sec, 0, sizeof(*sec));
254 INIT_LIST_HEAD(&sec->symbol_list);
255 INIT_LIST_HEAD(&sec->reloc_list);
257 s = elf_getscn(elf->elf, i);
259 WARN_ELF("elf_getscn");
263 sec->idx = elf_ndxscn(s);
265 if (!gelf_getshdr(s, &sec->sh)) {
266 WARN_ELF("gelf_getshdr");
270 sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
272 WARN_ELF("elf_strptr");
276 if (sec->sh.sh_size != 0) {
277 sec->data = elf_getdata(s, NULL);
279 WARN_ELF("elf_getdata");
282 if (sec->data->d_off != 0 ||
283 sec->data->d_size != sec->sh.sh_size) {
284 WARN("unexpected data attributes for %s",
290 if (sec->sh.sh_flags & SHF_EXECINSTR)
291 elf->text_size += sec->sh.sh_size;
293 list_add_tail(&sec->list, &elf->sections);
294 elf_hash_add(section, &sec->hash, sec->idx);
295 elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
299 printf("nr_sections: %lu\n", (unsigned long)sections_nr);
300 printf("section_bits: %d\n", elf->section_bits);
303 /* sanity check, one more call to elf_nextscn() should return NULL */
304 if (elf_nextscn(elf->elf, s)) {
305 WARN("section entry mismatch");
312 static void elf_add_symbol(struct elf *elf, struct symbol *sym)
314 struct list_head *entry;
315 struct rb_node *pnode;
319 sym->type = GELF_ST_TYPE(sym->sym.st_info);
320 sym->bind = GELF_ST_BIND(sym->sym.st_info);
322 sym->offset = sym->sym.st_value;
323 sym->len = sym->sym.st_size;
325 rb_add(&sym->node, &sym->sec->symbol_tree, symbol_to_offset);
326 pnode = rb_prev(&sym->node);
328 entry = &rb_entry(pnode, struct symbol, node)->list;
330 entry = &sym->sec->symbol_list;
331 list_add(&sym->list, entry);
332 elf_hash_add(symbol, &sym->hash, sym->idx);
333 elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
336 * Don't store empty STT_NOTYPE symbols in the rbtree. They
337 * can exist within a function, confusing the sorting.
340 rb_erase(&sym->node, &sym->sec->symbol_tree);
343 static int read_symbols(struct elf *elf)
345 struct section *symtab, *symtab_shndx, *sec;
346 struct symbol *sym, *pfunc;
349 Elf_Data *shndx_data = NULL;
352 symtab = find_section_by_name(elf, ".symtab");
354 symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
356 shndx_data = symtab_shndx->data;
358 symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
361 * A missing symbol table is actually possible if it's an empty
362 * .o file. This can happen for thunk_64.o. Make sure to at
363 * least allocate the symbol hash tables so we can do symbol
364 * lookups without crashing.
369 if (!elf_alloc_hash(symbol, symbols_nr) ||
370 !elf_alloc_hash(symbol_name, symbols_nr))
373 for (i = 0; i < symbols_nr; i++) {
374 sym = malloc(sizeof(*sym));
379 memset(sym, 0, sizeof(*sym));
383 if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
385 WARN_ELF("gelf_getsymshndx");
389 sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
392 WARN_ELF("elf_strptr");
396 if ((sym->sym.st_shndx > SHN_UNDEF &&
397 sym->sym.st_shndx < SHN_LORESERVE) ||
398 (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) {
399 if (sym->sym.st_shndx != SHN_XINDEX)
400 shndx = sym->sym.st_shndx;
402 sym->sec = find_section_by_index(elf, shndx);
404 WARN("couldn't find section for symbol %s",
408 if (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) {
409 sym->name = sym->sec->name;
413 sym->sec = find_section_by_index(elf, 0);
415 elf_add_symbol(elf, sym);
419 printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
420 printf("symbol_bits: %d\n", elf->symbol_bits);
423 /* Create parent/child links for any cold subfunctions */
424 list_for_each_entry(sec, &elf->sections, list) {
425 list_for_each_entry(sym, &sec->symbol_list, list) {
426 char pname[MAX_NAME_LEN + 1];
428 if (sym->type != STT_FUNC)
431 if (sym->pfunc == NULL)
434 if (sym->cfunc == NULL)
437 coldstr = strstr(sym->name, ".cold");
441 pnamelen = coldstr - sym->name;
442 if (pnamelen > MAX_NAME_LEN) {
443 WARN("%s(): parent function name exceeds maximum length of %d characters",
444 sym->name, MAX_NAME_LEN);
448 strncpy(pname, sym->name, pnamelen);
449 pname[pnamelen] = '\0';
450 pfunc = find_symbol_by_name(elf, pname);
453 WARN("%s(): can't find parent function",
462 * Unfortunately, -fnoreorder-functions puts the child
463 * inside the parent. Remove the overlap so we can
464 * have sane assumptions.
466 * Note that pfunc->len now no longer matches
467 * pfunc->sym.st_size.
469 if (sym->sec == pfunc->sec &&
470 sym->offset >= pfunc->offset &&
471 sym->offset + sym->len == pfunc->offset + pfunc->len) {
472 pfunc->len -= sym->len;
484 static struct section *elf_create_reloc_section(struct elf *elf,
485 struct section *base,
488 int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset,
489 unsigned int type, struct symbol *sym, s64 addend)
493 if (!sec->reloc && !elf_create_reloc_section(elf, sec, SHT_RELA))
496 reloc = malloc(sizeof(*reloc));
501 memset(reloc, 0, sizeof(*reloc));
503 reloc->sec = sec->reloc;
504 reloc->offset = offset;
507 reloc->addend = addend;
509 list_add_tail(&reloc->list, &sec->reloc->reloc_list);
510 elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
512 sec->reloc->sh.sh_size += sec->reloc->sh.sh_entsize;
513 sec->reloc->changed = true;
519 * Ensure that any reloc section containing references to @sym is marked
520 * changed such that it will get re-generated in elf_rebuild_reloc_sections()
521 * with the new symbol index.
523 static void elf_dirty_reloc_sym(struct elf *elf, struct symbol *sym)
527 list_for_each_entry(sec, &elf->sections, list) {
533 list_for_each_entry(reloc, &sec->reloc_list, list) {
534 if (reloc->sym == sym) {
543 * The libelf API is terrible; gelf_update_sym*() takes a data block relative
544 * index value, *NOT* the symbol index. As such, iterate the data blocks and
545 * adjust index until it fits.
547 * If no data block is found, allow adding a new data block provided the index
548 * is only one past the end.
550 static int elf_update_symbol(struct elf *elf, struct section *symtab,
551 struct section *symtab_shndx, struct symbol *sym)
553 Elf32_Word shndx = sym->sec ? sym->sec->idx : SHN_UNDEF;
554 Elf_Data *symtab_data = NULL, *shndx_data = NULL;
555 Elf64_Xword entsize = symtab->sh.sh_entsize;
556 int max_idx, idx = sym->idx;
557 Elf_Scn *s, *t = NULL;
559 s = elf_getscn(elf->elf, symtab->idx);
561 WARN_ELF("elf_getscn");
566 t = elf_getscn(elf->elf, symtab_shndx->idx);
568 WARN_ELF("elf_getscn");
574 /* get next data descriptor for the relevant sections */
575 symtab_data = elf_getdata(s, symtab_data);
577 shndx_data = elf_getdata(t, shndx_data);
584 /* we don't do holes in symbol tables */
585 WARN("index out of range");
589 /* if @idx == 0, it's the next contiguous entry, create it */
590 symtab_data = elf_newdata(s);
592 shndx_data = elf_newdata(t);
594 buf = calloc(1, entsize);
600 symtab_data->d_buf = buf;
601 symtab_data->d_size = entsize;
602 symtab_data->d_align = 1;
603 symtab_data->d_type = ELF_T_SYM;
605 symtab->sh.sh_size += entsize;
606 symtab->changed = true;
609 shndx_data->d_buf = &sym->sec->idx;
610 shndx_data->d_size = sizeof(Elf32_Word);
611 shndx_data->d_align = sizeof(Elf32_Word);
612 shndx_data->d_type = ELF_T_WORD;
614 symtab_shndx->sh.sh_size += sizeof(Elf32_Word);
615 symtab_shndx->changed = true;
621 /* empty blocks should not happen */
622 if (!symtab_data->d_size) {
623 WARN("zero size data");
627 /* is this the right block? */
628 max_idx = symtab_data->d_size / entsize;
632 /* adjust index and try again */
636 /* something went side-ways */
638 WARN("negative index");
642 /* setup extended section index magic and write the symbol */
643 if (shndx >= SHN_UNDEF && shndx < SHN_LORESERVE) {
644 sym->sym.st_shndx = shndx;
648 sym->sym.st_shndx = SHN_XINDEX;
650 WARN("no .symtab_shndx");
655 if (!gelf_update_symshndx(symtab_data, shndx_data, idx, &sym->sym, shndx)) {
656 WARN_ELF("gelf_update_symshndx");
663 static struct symbol *
664 elf_create_section_symbol(struct elf *elf, struct section *sec)
666 struct section *symtab, *symtab_shndx;
667 Elf32_Word first_non_local, new_idx;
668 struct symbol *sym, *old;
670 symtab = find_section_by_name(elf, ".symtab");
672 symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
678 sym = calloc(1, sizeof(*sym));
684 sym->name = sec->name;
688 sym->sym.st_info = GELF_ST_INFO(STB_LOCAL, STT_SECTION);
694 * Move the first global symbol, as per sh_info, into a new, higher
695 * symbol index. This fees up a spot for a new local symbol.
697 first_non_local = symtab->sh.sh_info;
698 new_idx = symtab->sh.sh_size / symtab->sh.sh_entsize;
699 old = find_symbol_by_index(elf, first_non_local);
703 hlist_del(&old->hash);
704 elf_hash_add(symbol, &old->hash, old->idx);
706 elf_dirty_reloc_sym(elf, old);
708 if (elf_update_symbol(elf, symtab, symtab_shndx, old)) {
709 WARN("elf_update_symbol move");
713 new_idx = first_non_local;
717 if (elf_update_symbol(elf, symtab, symtab_shndx, sym)) {
718 WARN("elf_update_symbol");
723 * Either way, we added a LOCAL symbol.
725 symtab->sh.sh_info += 1;
727 elf_add_symbol(elf, sym);
732 int elf_add_reloc_to_insn(struct elf *elf, struct section *sec,
733 unsigned long offset, unsigned int type,
734 struct section *insn_sec, unsigned long insn_off)
736 struct symbol *sym = insn_sec->sym;
737 int addend = insn_off;
741 * Due to how weak functions work, we must use section based
742 * relocations. Symbol based relocations would result in the
743 * weak and non-weak function annotations being overlaid on the
744 * non-weak function after linking.
746 sym = elf_create_section_symbol(elf, insn_sec);
753 return elf_add_reloc(elf, sec, offset, type, sym, addend);
756 static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
758 if (!gelf_getrel(sec->data, i, &reloc->rel)) {
759 WARN_ELF("gelf_getrel");
762 reloc->type = GELF_R_TYPE(reloc->rel.r_info);
764 reloc->offset = reloc->rel.r_offset;
765 *symndx = GELF_R_SYM(reloc->rel.r_info);
769 static int read_rela_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
771 if (!gelf_getrela(sec->data, i, &reloc->rela)) {
772 WARN_ELF("gelf_getrela");
775 reloc->type = GELF_R_TYPE(reloc->rela.r_info);
776 reloc->addend = reloc->rela.r_addend;
777 reloc->offset = reloc->rela.r_offset;
778 *symndx = GELF_R_SYM(reloc->rela.r_info);
782 static int read_relocs(struct elf *elf)
788 unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0;
790 if (!elf_alloc_hash(reloc, elf->text_size / 16))
793 list_for_each_entry(sec, &elf->sections, list) {
794 if ((sec->sh.sh_type != SHT_RELA) &&
795 (sec->sh.sh_type != SHT_REL))
798 sec->base = find_section_by_index(elf, sec->sh.sh_info);
800 WARN("can't find base section for reloc section %s",
805 sec->base->reloc = sec;
808 for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
809 reloc = malloc(sizeof(*reloc));
814 memset(reloc, 0, sizeof(*reloc));
815 switch (sec->sh.sh_type) {
817 if (read_rel_reloc(sec, i, reloc, &symndx))
821 if (read_rela_reloc(sec, i, reloc, &symndx))
829 reloc->sym = find_symbol_by_index(elf, symndx);
831 WARN("can't find reloc entry symbol %d for %s",
836 list_add_tail(&reloc->list, &sec->reloc_list);
837 elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
841 max_reloc = max(max_reloc, nr_reloc);
842 tot_reloc += nr_reloc;
846 printf("max_reloc: %lu\n", max_reloc);
847 printf("tot_reloc: %lu\n", tot_reloc);
848 printf("reloc_bits: %d\n", elf->reloc_bits);
854 struct elf *elf_open_read(const char *name, int flags)
859 elf_version(EV_CURRENT);
861 elf = malloc(sizeof(*elf));
866 memset(elf, 0, offsetof(struct elf, sections));
868 INIT_LIST_HEAD(&elf->sections);
870 elf->fd = open(name, flags);
872 fprintf(stderr, "objtool: Can't open '%s': %s\n",
873 name, strerror(errno));
877 if ((flags & O_ACCMODE) == O_RDONLY)
878 cmd = ELF_C_READ_MMAP;
879 else if ((flags & O_ACCMODE) == O_RDWR)
884 elf->elf = elf_begin(elf->fd, cmd, NULL);
886 WARN_ELF("elf_begin");
890 if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
891 WARN_ELF("gelf_getehdr");
895 if (read_sections(elf))
898 if (read_symbols(elf))
901 if (read_relocs(elf))
911 static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
918 strtab = find_section_by_name(elf, ".strtab");
920 WARN("can't find .strtab section");
924 s = elf_getscn(elf->elf, strtab->idx);
926 WARN_ELF("elf_getscn");
930 data = elf_newdata(s);
932 WARN_ELF("elf_newdata");
937 data->d_size = strlen(str) + 1;
940 len = strtab->sh.sh_size;
941 strtab->sh.sh_size += data->d_size;
942 strtab->changed = true;
947 struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name)
949 struct section *symtab, *symtab_shndx;
954 sym = malloc(sizeof(*sym));
959 memset(sym, 0, sizeof(*sym));
961 sym->name = strdup(name);
963 sym->sym.st_name = elf_add_string(elf, NULL, sym->name);
964 if (sym->sym.st_name == -1)
967 sym->sym.st_info = GELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
973 symtab = find_section_by_name(elf, ".symtab");
975 WARN("can't find .symtab");
979 s = elf_getscn(elf->elf, symtab->idx);
981 WARN_ELF("elf_getscn");
985 data = elf_newdata(s);
987 WARN_ELF("elf_newdata");
991 data->d_buf = &sym->sym;
992 data->d_size = sizeof(sym->sym);
994 data->d_type = ELF_T_SYM;
996 sym->idx = symtab->sh.sh_size / sizeof(sym->sym);
998 symtab->sh.sh_size += data->d_size;
999 symtab->changed = true;
1001 symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
1003 s = elf_getscn(elf->elf, symtab_shndx->idx);
1005 WARN_ELF("elf_getscn");
1009 data = elf_newdata(s);
1011 WARN_ELF("elf_newdata");
1015 data->d_buf = &sym->sym.st_size; /* conveniently 0 */
1016 data->d_size = sizeof(Elf32_Word);
1018 data->d_type = ELF_T_WORD;
1020 symtab_shndx->sh.sh_size += 4;
1021 symtab_shndx->changed = true;
1024 sym->sec = find_section_by_index(elf, 0);
1026 elf_add_symbol(elf, sym);
1031 struct section *elf_create_section(struct elf *elf, const char *name,
1032 unsigned int sh_flags, size_t entsize, int nr)
1034 struct section *sec, *shstrtab;
1035 size_t size = entsize * nr;
1038 sec = malloc(sizeof(*sec));
1043 memset(sec, 0, sizeof(*sec));
1045 INIT_LIST_HEAD(&sec->symbol_list);
1046 INIT_LIST_HEAD(&sec->reloc_list);
1048 s = elf_newscn(elf->elf);
1050 WARN_ELF("elf_newscn");
1054 sec->name = strdup(name);
1060 sec->idx = elf_ndxscn(s);
1061 sec->changed = true;
1063 sec->data = elf_newdata(s);
1065 WARN_ELF("elf_newdata");
1069 sec->data->d_size = size;
1070 sec->data->d_align = 1;
1073 sec->data->d_buf = malloc(size);
1074 if (!sec->data->d_buf) {
1078 memset(sec->data->d_buf, 0, size);
1081 if (!gelf_getshdr(s, &sec->sh)) {
1082 WARN_ELF("gelf_getshdr");
1086 sec->sh.sh_size = size;
1087 sec->sh.sh_entsize = entsize;
1088 sec->sh.sh_type = SHT_PROGBITS;
1089 sec->sh.sh_addralign = 1;
1090 sec->sh.sh_flags = SHF_ALLOC | sh_flags;
1092 /* Add section name to .shstrtab (or .strtab for Clang) */
1093 shstrtab = find_section_by_name(elf, ".shstrtab");
1095 shstrtab = find_section_by_name(elf, ".strtab");
1097 WARN("can't find .shstrtab or .strtab section");
1100 sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
1101 if (sec->sh.sh_name == -1)
1104 list_add_tail(&sec->list, &elf->sections);
1105 elf_hash_add(section, &sec->hash, sec->idx);
1106 elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
1108 elf->changed = true;
1113 static struct section *elf_create_rel_reloc_section(struct elf *elf, struct section *base)
1116 struct section *sec;
1118 relocname = malloc(strlen(base->name) + strlen(".rel") + 1);
1123 strcpy(relocname, ".rel");
1124 strcat(relocname, base->name);
1126 sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rel), 0);
1134 sec->sh.sh_type = SHT_REL;
1135 sec->sh.sh_addralign = 8;
1136 sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
1137 sec->sh.sh_info = base->idx;
1138 sec->sh.sh_flags = SHF_INFO_LINK;
1143 static struct section *elf_create_rela_reloc_section(struct elf *elf, struct section *base)
1146 struct section *sec;
1148 relocname = malloc(strlen(base->name) + strlen(".rela") + 1);
1153 strcpy(relocname, ".rela");
1154 strcat(relocname, base->name);
1156 sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rela), 0);
1164 sec->sh.sh_type = SHT_RELA;
1165 sec->sh.sh_addralign = 8;
1166 sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
1167 sec->sh.sh_info = base->idx;
1168 sec->sh.sh_flags = SHF_INFO_LINK;
1173 static struct section *elf_create_reloc_section(struct elf *elf,
1174 struct section *base,
1178 case SHT_REL: return elf_create_rel_reloc_section(elf, base);
1179 case SHT_RELA: return elf_create_rela_reloc_section(elf, base);
1180 default: return NULL;
1184 static int elf_rebuild_rel_reloc_section(struct section *sec)
1186 struct reloc *reloc;
1190 /* Allocate a buffer for relocations */
1191 buf = malloc(sec->sh.sh_size);
1197 sec->data->d_buf = buf;
1198 sec->data->d_size = sec->sh.sh_size;
1199 sec->data->d_type = ELF_T_REL;
1202 list_for_each_entry(reloc, &sec->reloc_list, list) {
1203 reloc->rel.r_offset = reloc->offset;
1204 reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
1205 if (!gelf_update_rel(sec->data, idx, &reloc->rel)) {
1206 WARN_ELF("gelf_update_rel");
1215 static int elf_rebuild_rela_reloc_section(struct section *sec)
1217 struct reloc *reloc;
1221 /* Allocate a buffer for relocations with addends */
1222 buf = malloc(sec->sh.sh_size);
1228 sec->data->d_buf = buf;
1229 sec->data->d_size = sec->sh.sh_size;
1230 sec->data->d_type = ELF_T_RELA;
1233 list_for_each_entry(reloc, &sec->reloc_list, list) {
1234 reloc->rela.r_offset = reloc->offset;
1235 reloc->rela.r_addend = reloc->addend;
1236 reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
1237 if (!gelf_update_rela(sec->data, idx, &reloc->rela)) {
1238 WARN_ELF("gelf_update_rela");
1247 static int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
1249 switch (sec->sh.sh_type) {
1250 case SHT_REL: return elf_rebuild_rel_reloc_section(sec);
1251 case SHT_RELA: return elf_rebuild_rela_reloc_section(sec);
1256 int elf_write_insn(struct elf *elf, struct section *sec,
1257 unsigned long offset, unsigned int len,
1260 Elf_Data *data = sec->data;
1262 if (data->d_type != ELF_T_BYTE || data->d_off) {
1263 WARN("write to unexpected data for section: %s", sec->name);
1267 memcpy(data->d_buf + offset, insn, len);
1268 elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
1270 elf->changed = true;
1275 int elf_write_reloc(struct elf *elf, struct reloc *reloc)
1277 struct section *sec = reloc->sec;
1279 if (sec->sh.sh_type == SHT_REL) {
1280 reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
1281 reloc->rel.r_offset = reloc->offset;
1283 if (!gelf_update_rel(sec->data, reloc->idx, &reloc->rel)) {
1284 WARN_ELF("gelf_update_rel");
1288 reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
1289 reloc->rela.r_addend = reloc->addend;
1290 reloc->rela.r_offset = reloc->offset;
1292 if (!gelf_update_rela(sec->data, reloc->idx, &reloc->rela)) {
1293 WARN_ELF("gelf_update_rela");
1298 elf->changed = true;
1303 int elf_write(struct elf *elf)
1305 struct section *sec;
1308 /* Update changed relocation sections and section headers: */
1309 list_for_each_entry(sec, &elf->sections, list) {
1311 s = elf_getscn(elf->elf, sec->idx);
1313 WARN_ELF("elf_getscn");
1316 if (!gelf_update_shdr(s, &sec->sh)) {
1317 WARN_ELF("gelf_update_shdr");
1322 elf_rebuild_reloc_section(elf, sec)) {
1323 WARN("elf_rebuild_reloc_section");
1327 sec->changed = false;
1328 elf->changed = true;
1332 /* Make sure the new section header entries get updated properly. */
1333 elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
1335 /* Write all changes to the file. */
1336 if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
1337 WARN_ELF("elf_update");
1341 elf->changed = false;
1346 void elf_close(struct elf *elf)
1348 struct section *sec, *tmpsec;
1349 struct symbol *sym, *tmpsym;
1350 struct reloc *reloc, *tmpreloc;
1358 list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
1359 list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
1360 list_del(&sym->list);
1361 hash_del(&sym->hash);
1364 list_for_each_entry_safe(reloc, tmpreloc, &sec->reloc_list, list) {
1365 list_del(&reloc->list);
1366 hash_del(&reloc->hash);
1369 list_del(&sec->list);