1442f04c3SJosh Poimboeuf /* 2442f04c3SJosh Poimboeuf * elf.c - ELF access library 3442f04c3SJosh Poimboeuf * 4442f04c3SJosh Poimboeuf * Adapted from kpatch (https://github.com/dynup/kpatch): 5442f04c3SJosh Poimboeuf * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com> 6442f04c3SJosh Poimboeuf * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> 7442f04c3SJosh Poimboeuf * 8442f04c3SJosh Poimboeuf * This program is free software; you can redistribute it and/or 9442f04c3SJosh Poimboeuf * modify it under the terms of the GNU General Public License 10442f04c3SJosh Poimboeuf * as published by the Free Software Foundation; either version 2 11442f04c3SJosh Poimboeuf * of the License, or (at your option) any later version. 12442f04c3SJosh Poimboeuf * 13442f04c3SJosh Poimboeuf * This program is distributed in the hope that it will be useful, 14442f04c3SJosh Poimboeuf * but WITHOUT ANY WARRANTY; without even the implied warranty of 15442f04c3SJosh Poimboeuf * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16442f04c3SJosh Poimboeuf * GNU General Public License for more details. 17442f04c3SJosh Poimboeuf * 18442f04c3SJosh Poimboeuf * You should have received a copy of the GNU General Public License 19442f04c3SJosh Poimboeuf * along with this program; if not, see <http://www.gnu.org/licenses/>. 20442f04c3SJosh Poimboeuf */ 21442f04c3SJosh Poimboeuf 22442f04c3SJosh Poimboeuf #include <sys/types.h> 23442f04c3SJosh Poimboeuf #include <sys/stat.h> 24442f04c3SJosh Poimboeuf #include <fcntl.h> 25442f04c3SJosh Poimboeuf #include <stdio.h> 26442f04c3SJosh Poimboeuf #include <stdlib.h> 27442f04c3SJosh Poimboeuf #include <string.h> 28442f04c3SJosh Poimboeuf #include <unistd.h> 29385d11b1SJosh Poimboeuf #include <errno.h> 30442f04c3SJosh Poimboeuf 31442f04c3SJosh Poimboeuf #include "elf.h" 32442f04c3SJosh Poimboeuf #include "warn.h" 33442f04c3SJosh Poimboeuf 34442f04c3SJosh Poimboeuf struct section *find_section_by_name(struct elf *elf, const char *name) 35442f04c3SJosh Poimboeuf { 36442f04c3SJosh Poimboeuf struct section *sec; 37442f04c3SJosh Poimboeuf 38442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 39442f04c3SJosh Poimboeuf if (!strcmp(sec->name, name)) 40442f04c3SJosh Poimboeuf return sec; 41442f04c3SJosh Poimboeuf 42442f04c3SJosh Poimboeuf return NULL; 43442f04c3SJosh Poimboeuf } 44442f04c3SJosh Poimboeuf 45442f04c3SJosh Poimboeuf static struct section *find_section_by_index(struct elf *elf, 46442f04c3SJosh Poimboeuf unsigned int idx) 47442f04c3SJosh Poimboeuf { 48442f04c3SJosh Poimboeuf struct section *sec; 49442f04c3SJosh Poimboeuf 50442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 51442f04c3SJosh Poimboeuf if (sec->idx == idx) 52442f04c3SJosh Poimboeuf return sec; 53442f04c3SJosh Poimboeuf 54442f04c3SJosh Poimboeuf return NULL; 55442f04c3SJosh Poimboeuf } 56442f04c3SJosh Poimboeuf 57442f04c3SJosh Poimboeuf static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx) 58442f04c3SJosh Poimboeuf { 59442f04c3SJosh Poimboeuf struct section *sec; 60442f04c3SJosh Poimboeuf struct symbol *sym; 61442f04c3SJosh Poimboeuf 62442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 63042ba73fSJosh Poimboeuf hash_for_each_possible(sec->symbol_hash, sym, hash, idx) 64442f04c3SJosh Poimboeuf if (sym->idx == idx) 65442f04c3SJosh Poimboeuf return sym; 66442f04c3SJosh Poimboeuf 67442f04c3SJosh Poimboeuf return NULL; 68442f04c3SJosh Poimboeuf } 69442f04c3SJosh Poimboeuf 70442f04c3SJosh Poimboeuf struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset) 71442f04c3SJosh Poimboeuf { 72442f04c3SJosh Poimboeuf struct symbol *sym; 73442f04c3SJosh Poimboeuf 74a196e171SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 75442f04c3SJosh Poimboeuf if (sym->type != STT_SECTION && 76442f04c3SJosh Poimboeuf sym->offset == offset) 77442f04c3SJosh Poimboeuf return sym; 78442f04c3SJosh Poimboeuf 79442f04c3SJosh Poimboeuf return NULL; 80442f04c3SJosh Poimboeuf } 81442f04c3SJosh Poimboeuf 8213810435SJosh Poimboeuf struct symbol *find_symbol_by_name(struct elf *elf, const char *name) 8313810435SJosh Poimboeuf { 8413810435SJosh Poimboeuf struct section *sec; 8513810435SJosh Poimboeuf struct symbol *sym; 8613810435SJosh Poimboeuf 8713810435SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 8813810435SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 8913810435SJosh Poimboeuf if (!strcmp(sym->name, name)) 9013810435SJosh Poimboeuf return sym; 9113810435SJosh Poimboeuf 9213810435SJosh Poimboeuf return NULL; 9313810435SJosh Poimboeuf } 9413810435SJosh Poimboeuf 955c51f4aeSJosh Poimboeuf struct symbol *find_symbol_containing(struct section *sec, unsigned long offset) 965c51f4aeSJosh Poimboeuf { 975c51f4aeSJosh Poimboeuf struct symbol *sym; 985c51f4aeSJosh Poimboeuf 995c51f4aeSJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 1005c51f4aeSJosh Poimboeuf if (sym->type != STT_SECTION && 1015c51f4aeSJosh Poimboeuf offset >= sym->offset && offset < sym->offset + sym->len) 1025c51f4aeSJosh Poimboeuf return sym; 1035c51f4aeSJosh Poimboeuf 1045c51f4aeSJosh Poimboeuf return NULL; 1055c51f4aeSJosh Poimboeuf } 1065c51f4aeSJosh Poimboeuf 107442f04c3SJosh Poimboeuf struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, 108442f04c3SJosh Poimboeuf unsigned int len) 109442f04c3SJosh Poimboeuf { 110442f04c3SJosh Poimboeuf struct rela *rela; 111042ba73fSJosh Poimboeuf unsigned long o; 112442f04c3SJosh Poimboeuf 113442f04c3SJosh Poimboeuf if (!sec->rela) 114442f04c3SJosh Poimboeuf return NULL; 115442f04c3SJosh Poimboeuf 116042ba73fSJosh Poimboeuf for (o = offset; o < offset + len; o++) 117042ba73fSJosh Poimboeuf hash_for_each_possible(sec->rela->rela_hash, rela, hash, o) 118042ba73fSJosh Poimboeuf if (rela->offset == o) 119442f04c3SJosh Poimboeuf return rela; 120442f04c3SJosh Poimboeuf 121442f04c3SJosh Poimboeuf return NULL; 122442f04c3SJosh Poimboeuf } 123442f04c3SJosh Poimboeuf 124442f04c3SJosh Poimboeuf struct rela *find_rela_by_dest(struct section *sec, unsigned long offset) 125442f04c3SJosh Poimboeuf { 126442f04c3SJosh Poimboeuf return find_rela_by_dest_range(sec, offset, 1); 127442f04c3SJosh Poimboeuf } 128442f04c3SJosh Poimboeuf 129442f04c3SJosh Poimboeuf struct symbol *find_containing_func(struct section *sec, unsigned long offset) 130442f04c3SJosh Poimboeuf { 131442f04c3SJosh Poimboeuf struct symbol *func; 132442f04c3SJosh Poimboeuf 133a196e171SJosh Poimboeuf list_for_each_entry(func, &sec->symbol_list, list) 134442f04c3SJosh Poimboeuf if (func->type == STT_FUNC && offset >= func->offset && 135442f04c3SJosh Poimboeuf offset < func->offset + func->len) 136442f04c3SJosh Poimboeuf return func; 137442f04c3SJosh Poimboeuf 138442f04c3SJosh Poimboeuf return NULL; 139442f04c3SJosh Poimboeuf } 140442f04c3SJosh Poimboeuf 141442f04c3SJosh Poimboeuf static int read_sections(struct elf *elf) 142442f04c3SJosh Poimboeuf { 143442f04c3SJosh Poimboeuf Elf_Scn *s = NULL; 144442f04c3SJosh Poimboeuf struct section *sec; 145442f04c3SJosh Poimboeuf size_t shstrndx, sections_nr; 146442f04c3SJosh Poimboeuf int i; 147442f04c3SJosh Poimboeuf 148442f04c3SJosh Poimboeuf if (elf_getshdrnum(elf->elf, §ions_nr)) { 149baa41469SJosh Poimboeuf WARN_ELF("elf_getshdrnum"); 150442f04c3SJosh Poimboeuf return -1; 151442f04c3SJosh Poimboeuf } 152442f04c3SJosh Poimboeuf 153442f04c3SJosh Poimboeuf if (elf_getshdrstrndx(elf->elf, &shstrndx)) { 154baa41469SJosh Poimboeuf WARN_ELF("elf_getshdrstrndx"); 155442f04c3SJosh Poimboeuf return -1; 156442f04c3SJosh Poimboeuf } 157442f04c3SJosh Poimboeuf 158442f04c3SJosh Poimboeuf for (i = 0; i < sections_nr; i++) { 159442f04c3SJosh Poimboeuf sec = malloc(sizeof(*sec)); 160442f04c3SJosh Poimboeuf if (!sec) { 161442f04c3SJosh Poimboeuf perror("malloc"); 162442f04c3SJosh Poimboeuf return -1; 163442f04c3SJosh Poimboeuf } 164442f04c3SJosh Poimboeuf memset(sec, 0, sizeof(*sec)); 165442f04c3SJosh Poimboeuf 166a196e171SJosh Poimboeuf INIT_LIST_HEAD(&sec->symbol_list); 167a196e171SJosh Poimboeuf INIT_LIST_HEAD(&sec->rela_list); 168042ba73fSJosh Poimboeuf hash_init(sec->rela_hash); 169042ba73fSJosh Poimboeuf hash_init(sec->symbol_hash); 170442f04c3SJosh Poimboeuf 171442f04c3SJosh Poimboeuf list_add_tail(&sec->list, &elf->sections); 172442f04c3SJosh Poimboeuf 173442f04c3SJosh Poimboeuf s = elf_getscn(elf->elf, i); 174442f04c3SJosh Poimboeuf if (!s) { 175baa41469SJosh Poimboeuf WARN_ELF("elf_getscn"); 176442f04c3SJosh Poimboeuf return -1; 177442f04c3SJosh Poimboeuf } 178442f04c3SJosh Poimboeuf 179442f04c3SJosh Poimboeuf sec->idx = elf_ndxscn(s); 180442f04c3SJosh Poimboeuf 181442f04c3SJosh Poimboeuf if (!gelf_getshdr(s, &sec->sh)) { 182baa41469SJosh Poimboeuf WARN_ELF("gelf_getshdr"); 183442f04c3SJosh Poimboeuf return -1; 184442f04c3SJosh Poimboeuf } 185442f04c3SJosh Poimboeuf 186442f04c3SJosh Poimboeuf sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name); 187442f04c3SJosh Poimboeuf if (!sec->name) { 188baa41469SJosh Poimboeuf WARN_ELF("elf_strptr"); 189442f04c3SJosh Poimboeuf return -1; 190442f04c3SJosh Poimboeuf } 191442f04c3SJosh Poimboeuf 192df968c93SPetr Vandrovec if (sec->sh.sh_size != 0) { 193baa41469SJosh Poimboeuf sec->data = elf_getdata(s, NULL); 194baa41469SJosh Poimboeuf if (!sec->data) { 195baa41469SJosh Poimboeuf WARN_ELF("elf_getdata"); 196442f04c3SJosh Poimboeuf return -1; 197442f04c3SJosh Poimboeuf } 198baa41469SJosh Poimboeuf if (sec->data->d_off != 0 || 199baa41469SJosh Poimboeuf sec->data->d_size != sec->sh.sh_size) { 200df968c93SPetr Vandrovec WARN("unexpected data attributes for %s", 201df968c93SPetr Vandrovec sec->name); 202442f04c3SJosh Poimboeuf return -1; 203442f04c3SJosh Poimboeuf } 204df968c93SPetr Vandrovec } 205df968c93SPetr Vandrovec sec->len = sec->sh.sh_size; 206442f04c3SJosh Poimboeuf } 207442f04c3SJosh Poimboeuf 208442f04c3SJosh Poimboeuf /* sanity check, one more call to elf_nextscn() should return NULL */ 209442f04c3SJosh Poimboeuf if (elf_nextscn(elf->elf, s)) { 210442f04c3SJosh Poimboeuf WARN("section entry mismatch"); 211442f04c3SJosh Poimboeuf return -1; 212442f04c3SJosh Poimboeuf } 213442f04c3SJosh Poimboeuf 214442f04c3SJosh Poimboeuf return 0; 215442f04c3SJosh Poimboeuf } 216442f04c3SJosh Poimboeuf 217442f04c3SJosh Poimboeuf static int read_symbols(struct elf *elf) 218442f04c3SJosh Poimboeuf { 21913810435SJosh Poimboeuf struct section *symtab, *sec; 22013810435SJosh Poimboeuf struct symbol *sym, *pfunc; 221442f04c3SJosh Poimboeuf struct list_head *entry, *tmp; 222442f04c3SJosh Poimboeuf int symbols_nr, i; 22313810435SJosh Poimboeuf char *coldstr; 224442f04c3SJosh Poimboeuf 225442f04c3SJosh Poimboeuf symtab = find_section_by_name(elf, ".symtab"); 226442f04c3SJosh Poimboeuf if (!symtab) { 227442f04c3SJosh Poimboeuf WARN("missing symbol table"); 228442f04c3SJosh Poimboeuf return -1; 229442f04c3SJosh Poimboeuf } 230442f04c3SJosh Poimboeuf 231442f04c3SJosh Poimboeuf symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize; 232442f04c3SJosh Poimboeuf 233442f04c3SJosh Poimboeuf for (i = 0; i < symbols_nr; i++) { 234442f04c3SJosh Poimboeuf sym = malloc(sizeof(*sym)); 235442f04c3SJosh Poimboeuf if (!sym) { 236442f04c3SJosh Poimboeuf perror("malloc"); 237442f04c3SJosh Poimboeuf return -1; 238442f04c3SJosh Poimboeuf } 239442f04c3SJosh Poimboeuf memset(sym, 0, sizeof(*sym)); 240442f04c3SJosh Poimboeuf 241442f04c3SJosh Poimboeuf sym->idx = i; 242442f04c3SJosh Poimboeuf 243baa41469SJosh Poimboeuf if (!gelf_getsym(symtab->data, i, &sym->sym)) { 244baa41469SJosh Poimboeuf WARN_ELF("gelf_getsym"); 245442f04c3SJosh Poimboeuf goto err; 246442f04c3SJosh Poimboeuf } 247442f04c3SJosh Poimboeuf 248442f04c3SJosh Poimboeuf sym->name = elf_strptr(elf->elf, symtab->sh.sh_link, 249442f04c3SJosh Poimboeuf sym->sym.st_name); 250442f04c3SJosh Poimboeuf if (!sym->name) { 251baa41469SJosh Poimboeuf WARN_ELF("elf_strptr"); 252442f04c3SJosh Poimboeuf goto err; 253442f04c3SJosh Poimboeuf } 254442f04c3SJosh Poimboeuf 255442f04c3SJosh Poimboeuf sym->type = GELF_ST_TYPE(sym->sym.st_info); 256442f04c3SJosh Poimboeuf sym->bind = GELF_ST_BIND(sym->sym.st_info); 257442f04c3SJosh Poimboeuf 258442f04c3SJosh Poimboeuf if (sym->sym.st_shndx > SHN_UNDEF && 259442f04c3SJosh Poimboeuf sym->sym.st_shndx < SHN_LORESERVE) { 260442f04c3SJosh Poimboeuf sym->sec = find_section_by_index(elf, 261442f04c3SJosh Poimboeuf sym->sym.st_shndx); 262442f04c3SJosh Poimboeuf if (!sym->sec) { 263442f04c3SJosh Poimboeuf WARN("couldn't find section for symbol %s", 264442f04c3SJosh Poimboeuf sym->name); 265442f04c3SJosh Poimboeuf goto err; 266442f04c3SJosh Poimboeuf } 267442f04c3SJosh Poimboeuf if (sym->type == STT_SECTION) { 268442f04c3SJosh Poimboeuf sym->name = sym->sec->name; 269442f04c3SJosh Poimboeuf sym->sec->sym = sym; 270442f04c3SJosh Poimboeuf } 271442f04c3SJosh Poimboeuf } else 272442f04c3SJosh Poimboeuf sym->sec = find_section_by_index(elf, 0); 273442f04c3SJosh Poimboeuf 274442f04c3SJosh Poimboeuf sym->offset = sym->sym.st_value; 275442f04c3SJosh Poimboeuf sym->len = sym->sym.st_size; 276442f04c3SJosh Poimboeuf 277442f04c3SJosh Poimboeuf /* sorted insert into a per-section list */ 278a196e171SJosh Poimboeuf entry = &sym->sec->symbol_list; 279a196e171SJosh Poimboeuf list_for_each_prev(tmp, &sym->sec->symbol_list) { 280442f04c3SJosh Poimboeuf struct symbol *s; 281442f04c3SJosh Poimboeuf 282442f04c3SJosh Poimboeuf s = list_entry(tmp, struct symbol, list); 283442f04c3SJosh Poimboeuf 284442f04c3SJosh Poimboeuf if (sym->offset > s->offset) { 285442f04c3SJosh Poimboeuf entry = tmp; 286442f04c3SJosh Poimboeuf break; 287442f04c3SJosh Poimboeuf } 288442f04c3SJosh Poimboeuf 289442f04c3SJosh Poimboeuf if (sym->offset == s->offset && sym->len >= s->len) { 290442f04c3SJosh Poimboeuf entry = tmp; 291442f04c3SJosh Poimboeuf break; 292442f04c3SJosh Poimboeuf } 293442f04c3SJosh Poimboeuf } 294442f04c3SJosh Poimboeuf list_add(&sym->list, entry); 295042ba73fSJosh Poimboeuf hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx); 296442f04c3SJosh Poimboeuf } 297442f04c3SJosh Poimboeuf 29813810435SJosh Poimboeuf /* Create parent/child links for any cold subfunctions */ 29913810435SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 30013810435SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) { 30113810435SJosh Poimboeuf if (sym->type != STT_FUNC) 30213810435SJosh Poimboeuf continue; 30313810435SJosh Poimboeuf sym->pfunc = sym->cfunc = sym; 30413810435SJosh Poimboeuf coldstr = strstr(sym->name, ".cold."); 30508b393d0SJosh Poimboeuf if (!coldstr) 30608b393d0SJosh Poimboeuf continue; 30708b393d0SJosh Poimboeuf 30813810435SJosh Poimboeuf coldstr[0] = '\0'; 30913810435SJosh Poimboeuf pfunc = find_symbol_by_name(elf, sym->name); 31013810435SJosh Poimboeuf coldstr[0] = '.'; 31113810435SJosh Poimboeuf 31213810435SJosh Poimboeuf if (!pfunc) { 31313810435SJosh Poimboeuf WARN("%s(): can't find parent function", 31413810435SJosh Poimboeuf sym->name); 31513810435SJosh Poimboeuf goto err; 31613810435SJosh Poimboeuf } 31713810435SJosh Poimboeuf 31813810435SJosh Poimboeuf sym->pfunc = pfunc; 31913810435SJosh Poimboeuf pfunc->cfunc = sym; 32008b393d0SJosh Poimboeuf 32108b393d0SJosh Poimboeuf /* 32208b393d0SJosh Poimboeuf * Unfortunately, -fnoreorder-functions puts the child 32308b393d0SJosh Poimboeuf * inside the parent. Remove the overlap so we can 32408b393d0SJosh Poimboeuf * have sane assumptions. 32508b393d0SJosh Poimboeuf * 32608b393d0SJosh Poimboeuf * Note that pfunc->len now no longer matches 32708b393d0SJosh Poimboeuf * pfunc->sym.st_size. 32808b393d0SJosh Poimboeuf */ 32908b393d0SJosh Poimboeuf if (sym->sec == pfunc->sec && 33008b393d0SJosh Poimboeuf sym->offset >= pfunc->offset && 33108b393d0SJosh Poimboeuf sym->offset + sym->len == pfunc->offset + pfunc->len) { 33208b393d0SJosh Poimboeuf pfunc->len -= sym->len; 33313810435SJosh Poimboeuf } 33413810435SJosh Poimboeuf } 33513810435SJosh Poimboeuf } 33613810435SJosh Poimboeuf 337442f04c3SJosh Poimboeuf return 0; 338442f04c3SJosh Poimboeuf 339442f04c3SJosh Poimboeuf err: 340442f04c3SJosh Poimboeuf free(sym); 341442f04c3SJosh Poimboeuf return -1; 342442f04c3SJosh Poimboeuf } 343442f04c3SJosh Poimboeuf 344442f04c3SJosh Poimboeuf static int read_relas(struct elf *elf) 345442f04c3SJosh Poimboeuf { 346442f04c3SJosh Poimboeuf struct section *sec; 347442f04c3SJosh Poimboeuf struct rela *rela; 348442f04c3SJosh Poimboeuf int i; 349442f04c3SJosh Poimboeuf unsigned int symndx; 350442f04c3SJosh Poimboeuf 351442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 352442f04c3SJosh Poimboeuf if (sec->sh.sh_type != SHT_RELA) 353442f04c3SJosh Poimboeuf continue; 354442f04c3SJosh Poimboeuf 355442f04c3SJosh Poimboeuf sec->base = find_section_by_name(elf, sec->name + 5); 356442f04c3SJosh Poimboeuf if (!sec->base) { 357442f04c3SJosh Poimboeuf WARN("can't find base section for rela section %s", 358442f04c3SJosh Poimboeuf sec->name); 359442f04c3SJosh Poimboeuf return -1; 360442f04c3SJosh Poimboeuf } 361442f04c3SJosh Poimboeuf 362442f04c3SJosh Poimboeuf sec->base->rela = sec; 363442f04c3SJosh Poimboeuf 364442f04c3SJosh Poimboeuf for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) { 365442f04c3SJosh Poimboeuf rela = malloc(sizeof(*rela)); 366442f04c3SJosh Poimboeuf if (!rela) { 367442f04c3SJosh Poimboeuf perror("malloc"); 368442f04c3SJosh Poimboeuf return -1; 369442f04c3SJosh Poimboeuf } 370442f04c3SJosh Poimboeuf memset(rela, 0, sizeof(*rela)); 371442f04c3SJosh Poimboeuf 372baa41469SJosh Poimboeuf if (!gelf_getrela(sec->data, i, &rela->rela)) { 373baa41469SJosh Poimboeuf WARN_ELF("gelf_getrela"); 374442f04c3SJosh Poimboeuf return -1; 375442f04c3SJosh Poimboeuf } 376442f04c3SJosh Poimboeuf 377442f04c3SJosh Poimboeuf rela->type = GELF_R_TYPE(rela->rela.r_info); 378442f04c3SJosh Poimboeuf rela->addend = rela->rela.r_addend; 379442f04c3SJosh Poimboeuf rela->offset = rela->rela.r_offset; 380442f04c3SJosh Poimboeuf symndx = GELF_R_SYM(rela->rela.r_info); 381442f04c3SJosh Poimboeuf rela->sym = find_symbol_by_index(elf, symndx); 3824a60aa05SAllan Xavier rela->rela_sec = sec; 383442f04c3SJosh Poimboeuf if (!rela->sym) { 384442f04c3SJosh Poimboeuf WARN("can't find rela entry symbol %d for %s", 385442f04c3SJosh Poimboeuf symndx, sec->name); 386442f04c3SJosh Poimboeuf return -1; 387442f04c3SJosh Poimboeuf } 388042ba73fSJosh Poimboeuf 389042ba73fSJosh Poimboeuf list_add_tail(&rela->list, &sec->rela_list); 390042ba73fSJosh Poimboeuf hash_add(sec->rela_hash, &rela->hash, rela->offset); 391042ba73fSJosh Poimboeuf 392442f04c3SJosh Poimboeuf } 393442f04c3SJosh Poimboeuf } 394442f04c3SJosh Poimboeuf 395442f04c3SJosh Poimboeuf return 0; 396442f04c3SJosh Poimboeuf } 397442f04c3SJosh Poimboeuf 398627fce14SJosh Poimboeuf struct elf *elf_open(const char *name, int flags) 399442f04c3SJosh Poimboeuf { 400442f04c3SJosh Poimboeuf struct elf *elf; 401627fce14SJosh Poimboeuf Elf_Cmd cmd; 402442f04c3SJosh Poimboeuf 403442f04c3SJosh Poimboeuf elf_version(EV_CURRENT); 404442f04c3SJosh Poimboeuf 405442f04c3SJosh Poimboeuf elf = malloc(sizeof(*elf)); 406442f04c3SJosh Poimboeuf if (!elf) { 407442f04c3SJosh Poimboeuf perror("malloc"); 408442f04c3SJosh Poimboeuf return NULL; 409442f04c3SJosh Poimboeuf } 410442f04c3SJosh Poimboeuf memset(elf, 0, sizeof(*elf)); 411442f04c3SJosh Poimboeuf 412442f04c3SJosh Poimboeuf INIT_LIST_HEAD(&elf->sections); 413442f04c3SJosh Poimboeuf 414627fce14SJosh Poimboeuf elf->fd = open(name, flags); 415442f04c3SJosh Poimboeuf if (elf->fd == -1) { 416385d11b1SJosh Poimboeuf fprintf(stderr, "objtool: Can't open '%s': %s\n", 417385d11b1SJosh Poimboeuf name, strerror(errno)); 418442f04c3SJosh Poimboeuf goto err; 419442f04c3SJosh Poimboeuf } 420442f04c3SJosh Poimboeuf 421627fce14SJosh Poimboeuf if ((flags & O_ACCMODE) == O_RDONLY) 422627fce14SJosh Poimboeuf cmd = ELF_C_READ_MMAP; 423627fce14SJosh Poimboeuf else if ((flags & O_ACCMODE) == O_RDWR) 424627fce14SJosh Poimboeuf cmd = ELF_C_RDWR; 425627fce14SJosh Poimboeuf else /* O_WRONLY */ 426627fce14SJosh Poimboeuf cmd = ELF_C_WRITE; 427627fce14SJosh Poimboeuf 428627fce14SJosh Poimboeuf elf->elf = elf_begin(elf->fd, cmd, NULL); 429442f04c3SJosh Poimboeuf if (!elf->elf) { 430baa41469SJosh Poimboeuf WARN_ELF("elf_begin"); 431442f04c3SJosh Poimboeuf goto err; 432442f04c3SJosh Poimboeuf } 433442f04c3SJosh Poimboeuf 434442f04c3SJosh Poimboeuf if (!gelf_getehdr(elf->elf, &elf->ehdr)) { 435baa41469SJosh Poimboeuf WARN_ELF("gelf_getehdr"); 436442f04c3SJosh Poimboeuf goto err; 437442f04c3SJosh Poimboeuf } 438442f04c3SJosh Poimboeuf 439442f04c3SJosh Poimboeuf if (read_sections(elf)) 440442f04c3SJosh Poimboeuf goto err; 441442f04c3SJosh Poimboeuf 442442f04c3SJosh Poimboeuf if (read_symbols(elf)) 443442f04c3SJosh Poimboeuf goto err; 444442f04c3SJosh Poimboeuf 445442f04c3SJosh Poimboeuf if (read_relas(elf)) 446442f04c3SJosh Poimboeuf goto err; 447442f04c3SJosh Poimboeuf 448442f04c3SJosh Poimboeuf return elf; 449442f04c3SJosh Poimboeuf 450442f04c3SJosh Poimboeuf err: 451442f04c3SJosh Poimboeuf elf_close(elf); 452442f04c3SJosh Poimboeuf return NULL; 453442f04c3SJosh Poimboeuf } 454442f04c3SJosh Poimboeuf 455627fce14SJosh Poimboeuf struct section *elf_create_section(struct elf *elf, const char *name, 456627fce14SJosh Poimboeuf size_t entsize, int nr) 457627fce14SJosh Poimboeuf { 458627fce14SJosh Poimboeuf struct section *sec, *shstrtab; 459627fce14SJosh Poimboeuf size_t size = entsize * nr; 460627fce14SJosh Poimboeuf struct Elf_Scn *s; 461627fce14SJosh Poimboeuf Elf_Data *data; 462627fce14SJosh Poimboeuf 463627fce14SJosh Poimboeuf sec = malloc(sizeof(*sec)); 464627fce14SJosh Poimboeuf if (!sec) { 465627fce14SJosh Poimboeuf perror("malloc"); 466627fce14SJosh Poimboeuf return NULL; 467627fce14SJosh Poimboeuf } 468627fce14SJosh Poimboeuf memset(sec, 0, sizeof(*sec)); 469627fce14SJosh Poimboeuf 470627fce14SJosh Poimboeuf INIT_LIST_HEAD(&sec->symbol_list); 471627fce14SJosh Poimboeuf INIT_LIST_HEAD(&sec->rela_list); 472627fce14SJosh Poimboeuf hash_init(sec->rela_hash); 473627fce14SJosh Poimboeuf hash_init(sec->symbol_hash); 474627fce14SJosh Poimboeuf 475627fce14SJosh Poimboeuf list_add_tail(&sec->list, &elf->sections); 476627fce14SJosh Poimboeuf 477627fce14SJosh Poimboeuf s = elf_newscn(elf->elf); 478627fce14SJosh Poimboeuf if (!s) { 479627fce14SJosh Poimboeuf WARN_ELF("elf_newscn"); 480627fce14SJosh Poimboeuf return NULL; 481627fce14SJosh Poimboeuf } 482627fce14SJosh Poimboeuf 483627fce14SJosh Poimboeuf sec->name = strdup(name); 484627fce14SJosh Poimboeuf if (!sec->name) { 485627fce14SJosh Poimboeuf perror("strdup"); 486627fce14SJosh Poimboeuf return NULL; 487627fce14SJosh Poimboeuf } 488627fce14SJosh Poimboeuf 489627fce14SJosh Poimboeuf sec->idx = elf_ndxscn(s); 490627fce14SJosh Poimboeuf sec->len = size; 491627fce14SJosh Poimboeuf sec->changed = true; 492627fce14SJosh Poimboeuf 493627fce14SJosh Poimboeuf sec->data = elf_newdata(s); 494627fce14SJosh Poimboeuf if (!sec->data) { 495627fce14SJosh Poimboeuf WARN_ELF("elf_newdata"); 496627fce14SJosh Poimboeuf return NULL; 497627fce14SJosh Poimboeuf } 498627fce14SJosh Poimboeuf 499627fce14SJosh Poimboeuf sec->data->d_size = size; 500627fce14SJosh Poimboeuf sec->data->d_align = 1; 501627fce14SJosh Poimboeuf 502627fce14SJosh Poimboeuf if (size) { 503627fce14SJosh Poimboeuf sec->data->d_buf = malloc(size); 504627fce14SJosh Poimboeuf if (!sec->data->d_buf) { 505627fce14SJosh Poimboeuf perror("malloc"); 506627fce14SJosh Poimboeuf return NULL; 507627fce14SJosh Poimboeuf } 508627fce14SJosh Poimboeuf memset(sec->data->d_buf, 0, size); 509627fce14SJosh Poimboeuf } 510627fce14SJosh Poimboeuf 511627fce14SJosh Poimboeuf if (!gelf_getshdr(s, &sec->sh)) { 512627fce14SJosh Poimboeuf WARN_ELF("gelf_getshdr"); 513627fce14SJosh Poimboeuf return NULL; 514627fce14SJosh Poimboeuf } 515627fce14SJosh Poimboeuf 516627fce14SJosh Poimboeuf sec->sh.sh_size = size; 517627fce14SJosh Poimboeuf sec->sh.sh_entsize = entsize; 518627fce14SJosh Poimboeuf sec->sh.sh_type = SHT_PROGBITS; 519627fce14SJosh Poimboeuf sec->sh.sh_addralign = 1; 520627fce14SJosh Poimboeuf sec->sh.sh_flags = SHF_ALLOC; 521627fce14SJosh Poimboeuf 522627fce14SJosh Poimboeuf 5236d77d3b4SSimon Ser /* Add section name to .shstrtab (or .strtab for Clang) */ 524627fce14SJosh Poimboeuf shstrtab = find_section_by_name(elf, ".shstrtab"); 5256d77d3b4SSimon Ser if (!shstrtab) 5266d77d3b4SSimon Ser shstrtab = find_section_by_name(elf, ".strtab"); 527627fce14SJosh Poimboeuf if (!shstrtab) { 5286d77d3b4SSimon Ser WARN("can't find .shstrtab or .strtab section"); 529627fce14SJosh Poimboeuf return NULL; 530627fce14SJosh Poimboeuf } 531627fce14SJosh Poimboeuf 532627fce14SJosh Poimboeuf s = elf_getscn(elf->elf, shstrtab->idx); 533627fce14SJosh Poimboeuf if (!s) { 534627fce14SJosh Poimboeuf WARN_ELF("elf_getscn"); 535627fce14SJosh Poimboeuf return NULL; 536627fce14SJosh Poimboeuf } 537627fce14SJosh Poimboeuf 538627fce14SJosh Poimboeuf data = elf_newdata(s); 539627fce14SJosh Poimboeuf if (!data) { 540627fce14SJosh Poimboeuf WARN_ELF("elf_newdata"); 541627fce14SJosh Poimboeuf return NULL; 542627fce14SJosh Poimboeuf } 543627fce14SJosh Poimboeuf 544627fce14SJosh Poimboeuf data->d_buf = sec->name; 545627fce14SJosh Poimboeuf data->d_size = strlen(name) + 1; 546627fce14SJosh Poimboeuf data->d_align = 1; 547627fce14SJosh Poimboeuf 548627fce14SJosh Poimboeuf sec->sh.sh_name = shstrtab->len; 549627fce14SJosh Poimboeuf 550627fce14SJosh Poimboeuf shstrtab->len += strlen(name) + 1; 551627fce14SJosh Poimboeuf shstrtab->changed = true; 552627fce14SJosh Poimboeuf 553627fce14SJosh Poimboeuf return sec; 554627fce14SJosh Poimboeuf } 555627fce14SJosh Poimboeuf 556627fce14SJosh Poimboeuf struct section *elf_create_rela_section(struct elf *elf, struct section *base) 557627fce14SJosh Poimboeuf { 558627fce14SJosh Poimboeuf char *relaname; 559627fce14SJosh Poimboeuf struct section *sec; 560627fce14SJosh Poimboeuf 561627fce14SJosh Poimboeuf relaname = malloc(strlen(base->name) + strlen(".rela") + 1); 562627fce14SJosh Poimboeuf if (!relaname) { 563627fce14SJosh Poimboeuf perror("malloc"); 564627fce14SJosh Poimboeuf return NULL; 565627fce14SJosh Poimboeuf } 566627fce14SJosh Poimboeuf strcpy(relaname, ".rela"); 567627fce14SJosh Poimboeuf strcat(relaname, base->name); 568627fce14SJosh Poimboeuf 569627fce14SJosh Poimboeuf sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0); 5700998b7a0SMartin Kepplinger free(relaname); 571627fce14SJosh Poimboeuf if (!sec) 572627fce14SJosh Poimboeuf return NULL; 573627fce14SJosh Poimboeuf 574627fce14SJosh Poimboeuf base->rela = sec; 575627fce14SJosh Poimboeuf sec->base = base; 576627fce14SJosh Poimboeuf 577627fce14SJosh Poimboeuf sec->sh.sh_type = SHT_RELA; 578627fce14SJosh Poimboeuf sec->sh.sh_addralign = 8; 579627fce14SJosh Poimboeuf sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx; 580627fce14SJosh Poimboeuf sec->sh.sh_info = base->idx; 581627fce14SJosh Poimboeuf sec->sh.sh_flags = SHF_INFO_LINK; 582627fce14SJosh Poimboeuf 583627fce14SJosh Poimboeuf return sec; 584627fce14SJosh Poimboeuf } 585627fce14SJosh Poimboeuf 586627fce14SJosh Poimboeuf int elf_rebuild_rela_section(struct section *sec) 587627fce14SJosh Poimboeuf { 588627fce14SJosh Poimboeuf struct rela *rela; 589627fce14SJosh Poimboeuf int nr, idx = 0, size; 590627fce14SJosh Poimboeuf GElf_Rela *relas; 591627fce14SJosh Poimboeuf 592627fce14SJosh Poimboeuf nr = 0; 593627fce14SJosh Poimboeuf list_for_each_entry(rela, &sec->rela_list, list) 594627fce14SJosh Poimboeuf nr++; 595627fce14SJosh Poimboeuf 596627fce14SJosh Poimboeuf size = nr * sizeof(*relas); 597627fce14SJosh Poimboeuf relas = malloc(size); 598627fce14SJosh Poimboeuf if (!relas) { 599627fce14SJosh Poimboeuf perror("malloc"); 600627fce14SJosh Poimboeuf return -1; 601627fce14SJosh Poimboeuf } 602627fce14SJosh Poimboeuf 603627fce14SJosh Poimboeuf sec->data->d_buf = relas; 604627fce14SJosh Poimboeuf sec->data->d_size = size; 605627fce14SJosh Poimboeuf 606627fce14SJosh Poimboeuf sec->sh.sh_size = size; 607627fce14SJosh Poimboeuf 608627fce14SJosh Poimboeuf idx = 0; 609627fce14SJosh Poimboeuf list_for_each_entry(rela, &sec->rela_list, list) { 610627fce14SJosh Poimboeuf relas[idx].r_offset = rela->offset; 611627fce14SJosh Poimboeuf relas[idx].r_addend = rela->addend; 612627fce14SJosh Poimboeuf relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type); 613627fce14SJosh Poimboeuf idx++; 614627fce14SJosh Poimboeuf } 615627fce14SJosh Poimboeuf 616627fce14SJosh Poimboeuf return 0; 617627fce14SJosh Poimboeuf } 618627fce14SJosh Poimboeuf 619627fce14SJosh Poimboeuf int elf_write(struct elf *elf) 620627fce14SJosh Poimboeuf { 621627fce14SJosh Poimboeuf struct section *sec; 622627fce14SJosh Poimboeuf Elf_Scn *s; 623627fce14SJosh Poimboeuf 62497dab2aeSJosh Poimboeuf /* Update section headers for changed sections: */ 625627fce14SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 626627fce14SJosh Poimboeuf if (sec->changed) { 627627fce14SJosh Poimboeuf s = elf_getscn(elf->elf, sec->idx); 628627fce14SJosh Poimboeuf if (!s) { 629627fce14SJosh Poimboeuf WARN_ELF("elf_getscn"); 630627fce14SJosh Poimboeuf return -1; 631627fce14SJosh Poimboeuf } 632627fce14SJosh Poimboeuf if (!gelf_update_shdr(s, &sec->sh)) { 633627fce14SJosh Poimboeuf WARN_ELF("gelf_update_shdr"); 634627fce14SJosh Poimboeuf return -1; 635627fce14SJosh Poimboeuf } 636627fce14SJosh Poimboeuf } 637627fce14SJosh Poimboeuf } 638627fce14SJosh Poimboeuf 63997dab2aeSJosh Poimboeuf /* Make sure the new section header entries get updated properly. */ 64097dab2aeSJosh Poimboeuf elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY); 64197dab2aeSJosh Poimboeuf 64297dab2aeSJosh Poimboeuf /* Write all changes to the file. */ 643627fce14SJosh Poimboeuf if (elf_update(elf->elf, ELF_C_WRITE) < 0) { 644627fce14SJosh Poimboeuf WARN_ELF("elf_update"); 645627fce14SJosh Poimboeuf return -1; 646627fce14SJosh Poimboeuf } 647627fce14SJosh Poimboeuf 648627fce14SJosh Poimboeuf return 0; 649627fce14SJosh Poimboeuf } 650627fce14SJosh Poimboeuf 651442f04c3SJosh Poimboeuf void elf_close(struct elf *elf) 652442f04c3SJosh Poimboeuf { 653442f04c3SJosh Poimboeuf struct section *sec, *tmpsec; 654442f04c3SJosh Poimboeuf struct symbol *sym, *tmpsym; 655442f04c3SJosh Poimboeuf struct rela *rela, *tmprela; 656442f04c3SJosh Poimboeuf 657baa41469SJosh Poimboeuf if (elf->elf) 658baa41469SJosh Poimboeuf elf_end(elf->elf); 659baa41469SJosh Poimboeuf 660baa41469SJosh Poimboeuf if (elf->fd > 0) 661baa41469SJosh Poimboeuf close(elf->fd); 662baa41469SJosh Poimboeuf 663442f04c3SJosh Poimboeuf list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) { 664a196e171SJosh Poimboeuf list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) { 665442f04c3SJosh Poimboeuf list_del(&sym->list); 666042ba73fSJosh Poimboeuf hash_del(&sym->hash); 667442f04c3SJosh Poimboeuf free(sym); 668442f04c3SJosh Poimboeuf } 669a196e171SJosh Poimboeuf list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) { 670442f04c3SJosh Poimboeuf list_del(&rela->list); 671042ba73fSJosh Poimboeuf hash_del(&rela->hash); 672442f04c3SJosh Poimboeuf free(rela); 673442f04c3SJosh Poimboeuf } 674442f04c3SJosh Poimboeuf list_del(&sec->list); 675442f04c3SJosh Poimboeuf free(sec); 676442f04c3SJosh Poimboeuf } 677baa41469SJosh Poimboeuf 678442f04c3SJosh Poimboeuf free(elf); 679442f04c3SJosh Poimboeuf } 680