3  * elf.c - ELF access library
26 #include <objtool/elf.h>
34 #define __elf_table(name)	(elf->name##_hash)
35 #define __elf_bits(name)	(elf->name##_bits)
134 struct section *find_section_by_name(const struct elf *elf, const char *name)  in find_section_by_name()  argument
146 static struct section *find_section_by_index(struct elf *elf,  in find_section_by_index()  argument
159 static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)  in find_symbol_by_index()  argument
278 struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)  in find_symbol_by_name()  argument
291 static struct symbol *find_local_symbol_by_file_and_name(const struct elf *elf,  in find_local_symbol_by_file_and_name()  argument
307 struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *name)  in find_global_symbol_by_name()  argument
319 struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,  in find_reloc_by_dest_range()  argument
349 struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset)  in find_reloc_by_dest()  argument
351 	return find_reloc_by_dest_range(elf, sec, offset, 1);  in find_reloc_by_dest()
359 static int read_sections(struct elf *elf)  in read_sections()  argument
366 	if (elf_getshdrnum(elf->elf, &sections_nr)) {  in read_sections()
371 	if (elf_getshdrstrndx(elf->elf, &shstrndx)) {  in read_sections()
380 	elf->section_data = calloc(sections_nr, sizeof(*sec));  in read_sections()
381 	if (!elf->section_data) {  in read_sections()
386 		sec = &elf->section_data[i];  in read_sections()
390 		s = elf_getscn(elf->elf, i);  in read_sections()
403 		sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);  in read_sections()
422 		list_add_tail(&sec->list, &elf->sections);  in read_sections()
427 			elf->num_relocs += sec_num_entries(sec);  in read_sections()
432 		printf("section_bits: %d\n", elf->section_bits);  in read_sections()
436 	if (elf_nextscn(elf->elf, s)) {  in read_sections()
475 static int elf_add_symbol(struct elf *elf, struct symbol *sym)  in elf_add_symbol()  argument
488 		elf->num_files++;  in elf_add_symbol()
507 	list_add_tail(&sym->global_list, &elf->symbols);  in elf_add_symbol()
540 static int read_symbols(struct elf *elf)  in read_symbols()  argument
549 	symtab = find_section_by_name(elf, ".symtab");  in read_symbols()
551 		symtab_shndx = find_section_by_name(elf, ".symtab_shndx");  in read_symbols()
570 	elf->symbol_data = calloc(symbols_nr, sizeof(*sym));  in read_symbols()
571 	if (!elf->symbol_data) {  in read_symbols()
576 	INIT_LIST_HEAD(&elf->symbols);  in read_symbols()
579 		sym = &elf->symbol_data[i];  in read_symbols()
589 		sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,  in read_symbols()
602 			sym->sec = find_section_by_index(elf, shndx);  in read_symbols()
612 			sym->sec = find_section_by_index(elf, 0);  in read_symbols()
614 		if (elf_add_symbol(elf, sym))  in read_symbols()
625 		printf("symbol_bits: %d\n", elf->symbol_bits);  in read_symbols()
629 	list_for_each_entry(sec, &elf->sections, list) {  in read_symbols()
650 			pfunc = find_local_symbol_by_file_and_name(elf, sym->file, pname);  in read_symbols()
652 				pfunc = find_global_symbol_by_name(elf, pname);  in read_symbols()
683 static int mark_group_syms(struct elf *elf)  in mark_group_syms()  argument
688 	symtab = find_section_by_name(elf, ".symtab");  in mark_group_syms()
694 	for_each_sec(elf, sec) {  in mark_group_syms()
697 			sym = find_symbol_by_index(elf, sec->sh.sh_info);  in mark_group_syms()
714 static int elf_update_sym_relocs(struct elf *elf, struct symbol *sym)  in elf_update_sym_relocs()  argument
719 		set_reloc_sym(elf, reloc, reloc->sym->idx);  in elf_update_sym_relocs()
732 static int elf_update_symbol(struct elf *elf, struct section *symtab,  in elf_update_symbol()  argument
745 	s = elf_getscn(elf->elf, symtab->idx);  in elf_update_symbol()
752 		t = elf_getscn(elf->elf, symtab_shndx->idx);  in elf_update_symbol()
797 			mark_sec_changed(elf, symtab, true);  in elf_update_symbol()
812 				mark_sec_changed(elf, symtab_shndx, true);  in elf_update_symbol()
861 struct symbol *elf_create_symbol(struct elf *elf, const char *name,  in elf_create_symbol()  argument
883 		sym->sym.st_name = elf_add_string(elf, NULL, sym->name);  in elf_create_symbol()
891 		sym->sec = find_section_by_index(elf, 0);  in elf_create_symbol()
902 	symtab = find_section_by_name(elf, ".symtab");  in elf_create_symbol()
908 	symtab_shndx = find_section_by_name(elf, ".symtab_shndx");  in elf_create_symbol()
920 	old = find_symbol_by_index(elf, first_non_local);  in elf_create_symbol()
927 		if (elf_update_symbol(elf, symtab, symtab_shndx, old)) {  in elf_create_symbol()
932 		if (elf_update_sym_relocs(elf, old))  in elf_create_symbol()
937 			mark_sec_changed(elf, old->group_sec, true);  in elf_create_symbol()
950 	if (sym->idx && elf_update_symbol(elf, symtab, symtab_shndx, sym))  in elf_create_symbol()
954 	mark_sec_changed(elf, symtab, true);  in elf_create_symbol()
958 		mark_sec_changed(elf, symtab_shndx, true);  in elf_create_symbol()
961 	if (elf_add_symbol(elf, sym))  in elf_create_symbol()
967 struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec)  in elf_create_section_symbol()  argument
971 	sym = elf_create_symbol(elf, sec->name, sec, STB_LOCAL, STT_SECTION, 0, 0);  in elf_create_section_symbol()
980 struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,  in elf_init_reloc()  argument
1003 	set_reloc_offset(elf, reloc, offset);  in elf_init_reloc()
1004 	set_reloc_sym(elf, reloc, sym->idx);  in elf_init_reloc()
1005 	set_reloc_type(elf, reloc, type);  in elf_init_reloc()
1006 	set_reloc_addend(elf, reloc, addend);  in elf_init_reloc()
1015 struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,  in elf_init_reloc_text_sym()  argument
1036 		sym = elf_create_section_symbol(elf, insn_sec);  in elf_init_reloc_text_sym()
1041 	return elf_init_reloc(elf, sec->rsec, reloc_idx, offset, sym, addend,  in elf_init_reloc_text_sym()
1042 			      elf_text_rela_type(elf));  in elf_init_reloc_text_sym()
1045 struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,  in elf_init_reloc_data_sym()  argument
1056 	return elf_init_reloc(elf, sec->rsec, reloc_idx, offset, sym, addend,  in elf_init_reloc_data_sym()
1057 			      elf_data_rela_type(elf));  in elf_init_reloc_data_sym()
1060 static int read_relocs(struct elf *elf)  in read_relocs()  argument
1069 	if (!elf_alloc_hash(reloc, elf->num_relocs))  in read_relocs()
1072 	list_for_each_entry(rsec, &elf->sections, list) {  in read_relocs()
1076 		rsec->base = find_section_by_index(elf, rsec->sh.sh_info);  in read_relocs()
1099 			reloc->sym = sym = find_symbol_by_index(elf, symndx);  in read_relocs()
1116 		printf("num_relocs: %lu\n", elf->num_relocs);  in read_relocs()
1117 		printf("reloc_bits: %d\n", elf->reloc_bits);  in read_relocs()
1123 struct elf *elf_open_read(const char *name, int flags)  in elf_open_read()
1125 	struct elf *elf;  in elf_open_read()  local
1130 	elf = malloc(sizeof(*elf));  in elf_open_read()
1131 	if (!elf) {  in elf_open_read()
1135 	memset(elf, 0, sizeof(*elf));  in elf_open_read()
1137 	INIT_LIST_HEAD(&elf->sections);  in elf_open_read()
1139 	elf->fd = open(name, flags);  in elf_open_read()
1140 	if (elf->fd == -1) {  in elf_open_read()
1146 	elf->name = strdup(name);  in elf_open_read()
1147 	if (!elf->name) {  in elf_open_read()
1159 	elf->elf = elf_begin(elf->fd, cmd, NULL);  in elf_open_read()
1160 	if (!elf->elf) {  in elf_open_read()
1165 	if (!gelf_getehdr(elf->elf, &elf->ehdr)) {  in elf_open_read()
1170 	if (read_sections(elf))  in elf_open_read()
1173 	if (read_symbols(elf))  in elf_open_read()
1176 	if (mark_group_syms(elf))  in elf_open_read()
1179 	if (read_relocs(elf))  in elf_open_read()
1182 	return elf;  in elf_open_read()
1185 	elf_close(elf);  in elf_open_read()
1189 struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name)  in elf_create_file()
1194 	struct elf *elf;  in elf_create_file()  local
1198 	elf = calloc(1, sizeof(*elf));  in elf_create_file()
1199 	if (!elf) {  in elf_create_file()
1204 	INIT_LIST_HEAD(&elf->sections);  in elf_create_file()
1230 	elf->fd = mkstemp(tmp_name);  in elf_create_file()
1231 	if (elf->fd == -1) {  in elf_create_file()
1236 	elf->tmp_name = tmp_name;  in elf_create_file()
1238 	elf->name = strdup(name);  in elf_create_file()
1239 	if (!elf->name) {  in elf_create_file()
1244 	elf->elf = elf_begin(elf->fd, ELF_C_WRITE, NULL);  in elf_create_file()
1245 	if (!elf->elf) {  in elf_create_file()
1250 	if (!gelf_newehdr(elf->elf, ELFCLASS64)) {  in elf_create_file()
1255 	memcpy(&elf->ehdr, ehdr, sizeof(elf->ehdr));  in elf_create_file()
1257 	if (!gelf_update_ehdr(elf->elf, &elf->ehdr)) {  in elf_create_file()
1262 	INIT_LIST_HEAD(&elf->symbols);  in elf_create_file()
1271 	null		= elf_create_section(elf, NULL, 0, 0, SHT_NULL, 0, 0);  in elf_create_file()
1272 	shstrtab	= elf_create_section(elf, NULL, 0, 0, SHT_STRTAB, 1, 0);  in elf_create_file()
1273 	strtab		= elf_create_section(elf, NULL, 0, 0, SHT_STRTAB, 1, 0);  in elf_create_file()
1282 	null->sh.sh_name	= elf_add_string(elf, shstrtab, null->name);  in elf_create_file()
1283 	shstrtab->sh.sh_name	= elf_add_string(elf, shstrtab, shstrtab->name);  in elf_create_file()
1284 	strtab->sh.sh_name	= elf_add_string(elf, shstrtab, strtab->name);  in elf_create_file()
1293 	if (elf_add_string(elf, strtab, "") == -1)  in elf_create_file()
1296 	symtab = elf_create_section(elf, ".symtab", 0x18, 0x18, SHT_SYMTAB, 0x8, 0);  in elf_create_file()
1303 	elf->ehdr.e_shstrndx = shstrtab->idx;  in elf_create_file()
1304 	if (!gelf_update_ehdr(elf->elf, &elf->ehdr)) {  in elf_create_file()
1317 	elf_add_symbol(elf, sym);  in elf_create_file()
1319 	return elf;  in elf_create_file()
1322 unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str)  in elf_add_string()  argument
1327 		strtab = find_section_by_name(elf, ".strtab");  in elf_add_string()
1340 	if (!elf_add_data(elf, strtab, str, strlen(str) + 1))  in elf_add_string()
1346 void *elf_add_data(struct elf *elf, struct section *sec, const void *data, size_t size)  in elf_add_data()  argument
1356 	s = elf_getscn(elf->elf, sec->idx);  in elf_add_data()
1383 	mark_sec_changed(elf, sec, true);  in elf_add_data()
1388 struct section *elf_create_section(struct elf *elf, const char *name,  in elf_create_section()  argument
1396 	if (name && find_section_by_name(elf, name)) {  in elf_create_section()
1413 	s = elf_newscn(elf->elf);  in elf_create_section()
1457 		shstrtab = find_section_by_name(elf, ".shstrtab");  in elf_create_section()
1459 			shstrtab = find_section_by_name(elf, ".strtab");  in elf_create_section()
1465 		sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);  in elf_create_section()
1473 	list_add_tail(&sec->list, &elf->sections);  in elf_create_section()
1476 	mark_sec_changed(elf, sec, true);  in elf_create_section()
1481 static int elf_alloc_reloc(struct elf *elf, struct section *rsec)  in elf_alloc_reloc()  argument
1490 		rsec->data = elf_newdata(elf_getscn(elf->elf, rsec->idx));  in elf_alloc_reloc()
1501 	rsec->data->d_size = nr_relocs_new * elf_rela_size(elf);  in elf_alloc_reloc()
1515 		rsec->data->d_buf = malloc(nr_alloc * elf_rela_size(elf));  in elf_alloc_reloc()
1521 		       nr_relocs_old * elf_rela_size(elf));  in elf_alloc_reloc()
1524 					    nr_alloc * elf_rela_size(elf));  in elf_alloc_reloc()
1549 	for_each_sym(elf, sym) {  in elf_alloc_reloc()
1589 struct section *elf_create_rela_section(struct elf *elf, struct section *sec,  in elf_create_rela_section()  argument
1603 	rsec = elf_create_section(elf, rsec_name, nr_relocs * elf_rela_size(elf),  in elf_create_rela_section()
1604 				  elf_rela_size(elf), SHT_RELA, elf_addr_size(elf),  in elf_create_rela_section()
1621 	rsec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;  in elf_create_rela_section()
1630 struct reloc *elf_create_reloc(struct elf *elf, struct section *sec,  in elf_create_reloc()  argument
1638 		rsec = elf_create_rela_section(elf, sec, 0);  in elf_create_reloc()
1643 	if (find_reloc_by_dest(elf, sec, offset)) {  in elf_create_reloc()
1648 	if (elf_alloc_reloc(elf, rsec))  in elf_create_reloc()
1651 	mark_sec_changed(elf, rsec, true);  in elf_create_reloc()
1653 	return elf_init_reloc(elf, rsec, sec_num_entries(rsec) - 1, offset, sym,  in elf_create_reloc()
1657 struct section *elf_create_section_pair(struct elf *elf, const char *name,  in elf_create_section_pair()  argument
1663 	sec = elf_create_section(elf, name, nr * entsize, entsize,  in elf_create_section_pair()
1668 	if (!elf_create_rela_section(elf, sec, nr_relocs))  in elf_create_section_pair()
1674 int elf_write_insn(struct elf *elf, struct section *sec,  in elf_write_insn()  argument
1687 	mark_sec_changed(elf, sec, true);  in elf_write_insn()
1701 static int elf_truncate_section(struct elf *elf, struct section *sec)  in elf_truncate_section()  argument
1708 	s = elf_getscn(elf->elf, sec->idx);  in elf_truncate_section()
1745 int elf_write(struct elf *elf)  in elf_write()  argument
1751 	list_for_each_entry(sec, &elf->sections, list) {  in elf_write()
1752 		if (sec->truncate && elf_truncate_section(elf, sec))  in elf_write()
1756 			s = elf_getscn(elf->elf, sec->idx);  in elf_write()
1768 			mark_sec_changed(elf, sec, false);  in elf_write()
1773 	elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);  in elf_write()
1776 	if (elf_update(elf->elf, ELF_C_WRITE) < 0) {  in elf_write()
1781 	elf->changed = false;  in elf_write()
1786 int elf_close(struct elf *elf)  in elf_close()  argument
1788 	if (elf->elf)  in elf_close()
1789 		elf_end(elf->elf);  in elf_close()
1791 	if (elf->fd > 0)  in elf_close()
1792 		close(elf->fd);  in elf_close()
1794 	if (elf->tmp_name && rename(elf->tmp_name, elf->name))  in elf_close()