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 3422566c16SArtem Savkov #define MAX_NAME_LEN 128 3522566c16SArtem Savkov 36442f04c3SJosh Poimboeuf struct section *find_section_by_name(struct elf *elf, const char *name) 37442f04c3SJosh Poimboeuf { 38442f04c3SJosh Poimboeuf struct section *sec; 39442f04c3SJosh Poimboeuf 40442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 41442f04c3SJosh Poimboeuf if (!strcmp(sec->name, name)) 42442f04c3SJosh Poimboeuf return sec; 43442f04c3SJosh Poimboeuf 44442f04c3SJosh Poimboeuf return NULL; 45442f04c3SJosh Poimboeuf } 46442f04c3SJosh Poimboeuf 47442f04c3SJosh Poimboeuf static struct section *find_section_by_index(struct elf *elf, 48442f04c3SJosh Poimboeuf unsigned int idx) 49442f04c3SJosh Poimboeuf { 50442f04c3SJosh Poimboeuf struct section *sec; 51442f04c3SJosh Poimboeuf 52442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 53442f04c3SJosh Poimboeuf if (sec->idx == idx) 54442f04c3SJosh Poimboeuf return sec; 55442f04c3SJosh Poimboeuf 56442f04c3SJosh Poimboeuf return NULL; 57442f04c3SJosh Poimboeuf } 58442f04c3SJosh Poimboeuf 59442f04c3SJosh Poimboeuf static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx) 60442f04c3SJosh Poimboeuf { 61442f04c3SJosh Poimboeuf struct section *sec; 62442f04c3SJosh Poimboeuf struct symbol *sym; 63442f04c3SJosh Poimboeuf 64442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 65042ba73fSJosh Poimboeuf hash_for_each_possible(sec->symbol_hash, sym, hash, idx) 66442f04c3SJosh Poimboeuf if (sym->idx == idx) 67442f04c3SJosh Poimboeuf return sym; 68442f04c3SJosh Poimboeuf 69442f04c3SJosh Poimboeuf return NULL; 70442f04c3SJosh Poimboeuf } 71442f04c3SJosh Poimboeuf 72442f04c3SJosh Poimboeuf struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset) 73442f04c3SJosh Poimboeuf { 74442f04c3SJosh Poimboeuf struct symbol *sym; 75442f04c3SJosh Poimboeuf 76a196e171SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 77442f04c3SJosh Poimboeuf if (sym->type != STT_SECTION && 78442f04c3SJosh Poimboeuf sym->offset == offset) 79442f04c3SJosh Poimboeuf return sym; 80442f04c3SJosh Poimboeuf 81442f04c3SJosh Poimboeuf return NULL; 82442f04c3SJosh Poimboeuf } 83442f04c3SJosh Poimboeuf 8413810435SJosh Poimboeuf struct symbol *find_symbol_by_name(struct elf *elf, const char *name) 8513810435SJosh Poimboeuf { 8613810435SJosh Poimboeuf struct section *sec; 8713810435SJosh Poimboeuf struct symbol *sym; 8813810435SJosh Poimboeuf 8913810435SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 9013810435SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 9113810435SJosh Poimboeuf if (!strcmp(sym->name, name)) 9213810435SJosh Poimboeuf return sym; 9313810435SJosh Poimboeuf 9413810435SJosh Poimboeuf return NULL; 9513810435SJosh Poimboeuf } 9613810435SJosh Poimboeuf 975c51f4aeSJosh Poimboeuf struct symbol *find_symbol_containing(struct section *sec, unsigned long offset) 985c51f4aeSJosh Poimboeuf { 995c51f4aeSJosh Poimboeuf struct symbol *sym; 1005c51f4aeSJosh Poimboeuf 1015c51f4aeSJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 1025c51f4aeSJosh Poimboeuf if (sym->type != STT_SECTION && 1035c51f4aeSJosh Poimboeuf offset >= sym->offset && offset < sym->offset + sym->len) 1045c51f4aeSJosh Poimboeuf return sym; 1055c51f4aeSJosh Poimboeuf 1065c51f4aeSJosh Poimboeuf return NULL; 1075c51f4aeSJosh Poimboeuf } 1085c51f4aeSJosh Poimboeuf 109442f04c3SJosh Poimboeuf struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, 110442f04c3SJosh Poimboeuf unsigned int len) 111442f04c3SJosh Poimboeuf { 112442f04c3SJosh Poimboeuf struct rela *rela; 113042ba73fSJosh Poimboeuf unsigned long o; 114442f04c3SJosh Poimboeuf 115442f04c3SJosh Poimboeuf if (!sec->rela) 116442f04c3SJosh Poimboeuf return NULL; 117442f04c3SJosh Poimboeuf 118042ba73fSJosh Poimboeuf for (o = offset; o < offset + len; o++) 119042ba73fSJosh Poimboeuf hash_for_each_possible(sec->rela->rela_hash, rela, hash, o) 120042ba73fSJosh Poimboeuf if (rela->offset == o) 121442f04c3SJosh Poimboeuf return rela; 122442f04c3SJosh Poimboeuf 123442f04c3SJosh Poimboeuf return NULL; 124442f04c3SJosh Poimboeuf } 125442f04c3SJosh Poimboeuf 126442f04c3SJosh Poimboeuf struct rela *find_rela_by_dest(struct section *sec, unsigned long offset) 127442f04c3SJosh Poimboeuf { 128442f04c3SJosh Poimboeuf return find_rela_by_dest_range(sec, offset, 1); 129442f04c3SJosh Poimboeuf } 130442f04c3SJosh Poimboeuf 131442f04c3SJosh Poimboeuf struct symbol *find_containing_func(struct section *sec, unsigned long offset) 132442f04c3SJosh Poimboeuf { 133442f04c3SJosh Poimboeuf struct symbol *func; 134442f04c3SJosh Poimboeuf 135a196e171SJosh Poimboeuf list_for_each_entry(func, &sec->symbol_list, list) 136442f04c3SJosh Poimboeuf if (func->type == STT_FUNC && offset >= func->offset && 137442f04c3SJosh Poimboeuf offset < func->offset + func->len) 138442f04c3SJosh Poimboeuf return func; 139442f04c3SJosh Poimboeuf 140442f04c3SJosh Poimboeuf return NULL; 141442f04c3SJosh Poimboeuf } 142442f04c3SJosh Poimboeuf 143442f04c3SJosh Poimboeuf static int read_sections(struct elf *elf) 144442f04c3SJosh Poimboeuf { 145442f04c3SJosh Poimboeuf Elf_Scn *s = NULL; 146442f04c3SJosh Poimboeuf struct section *sec; 147442f04c3SJosh Poimboeuf size_t shstrndx, sections_nr; 148442f04c3SJosh Poimboeuf int i; 149442f04c3SJosh Poimboeuf 150442f04c3SJosh Poimboeuf if (elf_getshdrnum(elf->elf, §ions_nr)) { 151baa41469SJosh Poimboeuf WARN_ELF("elf_getshdrnum"); 152442f04c3SJosh Poimboeuf return -1; 153442f04c3SJosh Poimboeuf } 154442f04c3SJosh Poimboeuf 155442f04c3SJosh Poimboeuf if (elf_getshdrstrndx(elf->elf, &shstrndx)) { 156baa41469SJosh Poimboeuf WARN_ELF("elf_getshdrstrndx"); 157442f04c3SJosh Poimboeuf return -1; 158442f04c3SJosh Poimboeuf } 159442f04c3SJosh Poimboeuf 160442f04c3SJosh Poimboeuf for (i = 0; i < sections_nr; i++) { 161442f04c3SJosh Poimboeuf sec = malloc(sizeof(*sec)); 162442f04c3SJosh Poimboeuf if (!sec) { 163442f04c3SJosh Poimboeuf perror("malloc"); 164442f04c3SJosh Poimboeuf return -1; 165442f04c3SJosh Poimboeuf } 166442f04c3SJosh Poimboeuf memset(sec, 0, sizeof(*sec)); 167442f04c3SJosh Poimboeuf 168a196e171SJosh Poimboeuf INIT_LIST_HEAD(&sec->symbol_list); 169a196e171SJosh Poimboeuf INIT_LIST_HEAD(&sec->rela_list); 170042ba73fSJosh Poimboeuf hash_init(sec->rela_hash); 171042ba73fSJosh Poimboeuf hash_init(sec->symbol_hash); 172442f04c3SJosh Poimboeuf 173442f04c3SJosh Poimboeuf list_add_tail(&sec->list, &elf->sections); 174442f04c3SJosh Poimboeuf 175442f04c3SJosh Poimboeuf s = elf_getscn(elf->elf, i); 176442f04c3SJosh Poimboeuf if (!s) { 177baa41469SJosh Poimboeuf WARN_ELF("elf_getscn"); 178442f04c3SJosh Poimboeuf return -1; 179442f04c3SJosh Poimboeuf } 180442f04c3SJosh Poimboeuf 181442f04c3SJosh Poimboeuf sec->idx = elf_ndxscn(s); 182442f04c3SJosh Poimboeuf 183442f04c3SJosh Poimboeuf if (!gelf_getshdr(s, &sec->sh)) { 184baa41469SJosh Poimboeuf WARN_ELF("gelf_getshdr"); 185442f04c3SJosh Poimboeuf return -1; 186442f04c3SJosh Poimboeuf } 187442f04c3SJosh Poimboeuf 188442f04c3SJosh Poimboeuf sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name); 189442f04c3SJosh Poimboeuf if (!sec->name) { 190baa41469SJosh Poimboeuf WARN_ELF("elf_strptr"); 191442f04c3SJosh Poimboeuf return -1; 192442f04c3SJosh Poimboeuf } 193442f04c3SJosh Poimboeuf 194df968c93SPetr Vandrovec if (sec->sh.sh_size != 0) { 195baa41469SJosh Poimboeuf sec->data = elf_getdata(s, NULL); 196baa41469SJosh Poimboeuf if (!sec->data) { 197baa41469SJosh Poimboeuf WARN_ELF("elf_getdata"); 198442f04c3SJosh Poimboeuf return -1; 199442f04c3SJosh Poimboeuf } 200baa41469SJosh Poimboeuf if (sec->data->d_off != 0 || 201baa41469SJosh Poimboeuf sec->data->d_size != sec->sh.sh_size) { 202df968c93SPetr Vandrovec WARN("unexpected data attributes for %s", 203df968c93SPetr Vandrovec sec->name); 204442f04c3SJosh Poimboeuf return -1; 205442f04c3SJosh Poimboeuf } 206df968c93SPetr Vandrovec } 207df968c93SPetr Vandrovec sec->len = sec->sh.sh_size; 208442f04c3SJosh Poimboeuf } 209442f04c3SJosh Poimboeuf 210442f04c3SJosh Poimboeuf /* sanity check, one more call to elf_nextscn() should return NULL */ 211442f04c3SJosh Poimboeuf if (elf_nextscn(elf->elf, s)) { 212442f04c3SJosh Poimboeuf WARN("section entry mismatch"); 213442f04c3SJosh Poimboeuf return -1; 214442f04c3SJosh Poimboeuf } 215442f04c3SJosh Poimboeuf 216442f04c3SJosh Poimboeuf return 0; 217442f04c3SJosh Poimboeuf } 218442f04c3SJosh Poimboeuf 219442f04c3SJosh Poimboeuf static int read_symbols(struct elf *elf) 220442f04c3SJosh Poimboeuf { 22113810435SJosh Poimboeuf struct section *symtab, *sec; 22209f30d83SPeter Zijlstra struct symbol *sym, *pfunc, *alias; 223442f04c3SJosh Poimboeuf struct list_head *entry, *tmp; 224442f04c3SJosh Poimboeuf int symbols_nr, i; 22513810435SJosh Poimboeuf char *coldstr; 226442f04c3SJosh Poimboeuf 227442f04c3SJosh Poimboeuf symtab = find_section_by_name(elf, ".symtab"); 228442f04c3SJosh Poimboeuf if (!symtab) { 229442f04c3SJosh Poimboeuf WARN("missing symbol table"); 230442f04c3SJosh Poimboeuf return -1; 231442f04c3SJosh Poimboeuf } 232442f04c3SJosh Poimboeuf 233442f04c3SJosh Poimboeuf symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize; 234442f04c3SJosh Poimboeuf 235442f04c3SJosh Poimboeuf for (i = 0; i < symbols_nr; i++) { 236442f04c3SJosh Poimboeuf sym = malloc(sizeof(*sym)); 237442f04c3SJosh Poimboeuf if (!sym) { 238442f04c3SJosh Poimboeuf perror("malloc"); 239442f04c3SJosh Poimboeuf return -1; 240442f04c3SJosh Poimboeuf } 241442f04c3SJosh Poimboeuf memset(sym, 0, sizeof(*sym)); 24209f30d83SPeter Zijlstra alias = sym; 243442f04c3SJosh Poimboeuf 244442f04c3SJosh Poimboeuf sym->idx = i; 245442f04c3SJosh Poimboeuf 246baa41469SJosh Poimboeuf if (!gelf_getsym(symtab->data, i, &sym->sym)) { 247baa41469SJosh Poimboeuf WARN_ELF("gelf_getsym"); 248442f04c3SJosh Poimboeuf goto err; 249442f04c3SJosh Poimboeuf } 250442f04c3SJosh Poimboeuf 251442f04c3SJosh Poimboeuf sym->name = elf_strptr(elf->elf, symtab->sh.sh_link, 252442f04c3SJosh Poimboeuf sym->sym.st_name); 253442f04c3SJosh Poimboeuf if (!sym->name) { 254baa41469SJosh Poimboeuf WARN_ELF("elf_strptr"); 255442f04c3SJosh Poimboeuf goto err; 256442f04c3SJosh Poimboeuf } 257442f04c3SJosh Poimboeuf 258442f04c3SJosh Poimboeuf sym->type = GELF_ST_TYPE(sym->sym.st_info); 259442f04c3SJosh Poimboeuf sym->bind = GELF_ST_BIND(sym->sym.st_info); 260442f04c3SJosh Poimboeuf 261442f04c3SJosh Poimboeuf if (sym->sym.st_shndx > SHN_UNDEF && 262442f04c3SJosh Poimboeuf sym->sym.st_shndx < SHN_LORESERVE) { 263442f04c3SJosh Poimboeuf sym->sec = find_section_by_index(elf, 264442f04c3SJosh Poimboeuf sym->sym.st_shndx); 265442f04c3SJosh Poimboeuf if (!sym->sec) { 266442f04c3SJosh Poimboeuf WARN("couldn't find section for symbol %s", 267442f04c3SJosh Poimboeuf sym->name); 268442f04c3SJosh Poimboeuf goto err; 269442f04c3SJosh Poimboeuf } 270442f04c3SJosh Poimboeuf if (sym->type == STT_SECTION) { 271442f04c3SJosh Poimboeuf sym->name = sym->sec->name; 272442f04c3SJosh Poimboeuf sym->sec->sym = sym; 273442f04c3SJosh Poimboeuf } 274442f04c3SJosh Poimboeuf } else 275442f04c3SJosh Poimboeuf sym->sec = find_section_by_index(elf, 0); 276442f04c3SJosh Poimboeuf 277442f04c3SJosh Poimboeuf sym->offset = sym->sym.st_value; 278442f04c3SJosh Poimboeuf sym->len = sym->sym.st_size; 279442f04c3SJosh Poimboeuf 280442f04c3SJosh Poimboeuf /* sorted insert into a per-section list */ 281a196e171SJosh Poimboeuf entry = &sym->sec->symbol_list; 282a196e171SJosh Poimboeuf list_for_each_prev(tmp, &sym->sec->symbol_list) { 283442f04c3SJosh Poimboeuf struct symbol *s; 284442f04c3SJosh Poimboeuf 285442f04c3SJosh Poimboeuf s = list_entry(tmp, struct symbol, list); 286442f04c3SJosh Poimboeuf 287442f04c3SJosh Poimboeuf if (sym->offset > s->offset) { 288442f04c3SJosh Poimboeuf entry = tmp; 289442f04c3SJosh Poimboeuf break; 290442f04c3SJosh Poimboeuf } 291442f04c3SJosh Poimboeuf 29209f30d83SPeter Zijlstra if (sym->offset == s->offset) { 29309f30d83SPeter Zijlstra if (sym->len == s->len && alias == sym) 29409f30d83SPeter Zijlstra alias = s; 29509f30d83SPeter Zijlstra 29609f30d83SPeter Zijlstra if (sym->len >= s->len) { 297442f04c3SJosh Poimboeuf entry = tmp; 298442f04c3SJosh Poimboeuf break; 299442f04c3SJosh Poimboeuf } 300442f04c3SJosh Poimboeuf } 30109f30d83SPeter Zijlstra } 30209f30d83SPeter Zijlstra sym->alias = alias; 303442f04c3SJosh Poimboeuf list_add(&sym->list, entry); 304042ba73fSJosh Poimboeuf hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx); 305442f04c3SJosh Poimboeuf } 306442f04c3SJosh Poimboeuf 30713810435SJosh Poimboeuf /* Create parent/child links for any cold subfunctions */ 30813810435SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 30913810435SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) { 31022566c16SArtem Savkov char pname[MAX_NAME_LEN + 1]; 31122566c16SArtem Savkov size_t pnamelen; 31213810435SJosh Poimboeuf if (sym->type != STT_FUNC) 31313810435SJosh Poimboeuf continue; 31413810435SJosh Poimboeuf sym->pfunc = sym->cfunc = sym; 315bcb6fb5dSJosh Poimboeuf coldstr = strstr(sym->name, ".cold"); 31608b393d0SJosh Poimboeuf if (!coldstr) 31708b393d0SJosh Poimboeuf continue; 31808b393d0SJosh Poimboeuf 31922566c16SArtem Savkov pnamelen = coldstr - sym->name; 32022566c16SArtem Savkov if (pnamelen > MAX_NAME_LEN) { 32122566c16SArtem Savkov WARN("%s(): parent function name exceeds maximum length of %d characters", 32222566c16SArtem Savkov sym->name, MAX_NAME_LEN); 32322566c16SArtem Savkov return -1; 32422566c16SArtem Savkov } 32522566c16SArtem Savkov 32622566c16SArtem Savkov strncpy(pname, sym->name, pnamelen); 32722566c16SArtem Savkov pname[pnamelen] = '\0'; 32822566c16SArtem Savkov pfunc = find_symbol_by_name(elf, pname); 32913810435SJosh Poimboeuf 33013810435SJosh Poimboeuf if (!pfunc) { 33113810435SJosh Poimboeuf WARN("%s(): can't find parent function", 33213810435SJosh Poimboeuf sym->name); 3330b9301fbSArtem Savkov return -1; 33413810435SJosh Poimboeuf } 33513810435SJosh Poimboeuf 33613810435SJosh Poimboeuf sym->pfunc = pfunc; 33713810435SJosh Poimboeuf pfunc->cfunc = sym; 33808b393d0SJosh Poimboeuf 33908b393d0SJosh Poimboeuf /* 34008b393d0SJosh Poimboeuf * Unfortunately, -fnoreorder-functions puts the child 34108b393d0SJosh Poimboeuf * inside the parent. Remove the overlap so we can 34208b393d0SJosh Poimboeuf * have sane assumptions. 34308b393d0SJosh Poimboeuf * 34408b393d0SJosh Poimboeuf * Note that pfunc->len now no longer matches 34508b393d0SJosh Poimboeuf * pfunc->sym.st_size. 34608b393d0SJosh Poimboeuf */ 34708b393d0SJosh Poimboeuf if (sym->sec == pfunc->sec && 34808b393d0SJosh Poimboeuf sym->offset >= pfunc->offset && 34908b393d0SJosh Poimboeuf sym->offset + sym->len == pfunc->offset + pfunc->len) { 35008b393d0SJosh Poimboeuf pfunc->len -= sym->len; 35113810435SJosh Poimboeuf } 35213810435SJosh Poimboeuf } 35313810435SJosh Poimboeuf } 35413810435SJosh Poimboeuf 355442f04c3SJosh Poimboeuf return 0; 356442f04c3SJosh Poimboeuf 357442f04c3SJosh Poimboeuf err: 358442f04c3SJosh Poimboeuf free(sym); 359442f04c3SJosh Poimboeuf return -1; 360442f04c3SJosh Poimboeuf } 361442f04c3SJosh Poimboeuf 362442f04c3SJosh Poimboeuf static int read_relas(struct elf *elf) 363442f04c3SJosh Poimboeuf { 364442f04c3SJosh Poimboeuf struct section *sec; 365442f04c3SJosh Poimboeuf struct rela *rela; 366442f04c3SJosh Poimboeuf int i; 367442f04c3SJosh Poimboeuf unsigned int symndx; 368442f04c3SJosh Poimboeuf 369442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 370442f04c3SJosh Poimboeuf if (sec->sh.sh_type != SHT_RELA) 371442f04c3SJosh Poimboeuf continue; 372442f04c3SJosh Poimboeuf 373442f04c3SJosh Poimboeuf sec->base = find_section_by_name(elf, sec->name + 5); 374442f04c3SJosh Poimboeuf if (!sec->base) { 375442f04c3SJosh Poimboeuf WARN("can't find base section for rela section %s", 376442f04c3SJosh Poimboeuf sec->name); 377442f04c3SJosh Poimboeuf return -1; 378442f04c3SJosh Poimboeuf } 379442f04c3SJosh Poimboeuf 380442f04c3SJosh Poimboeuf sec->base->rela = sec; 381442f04c3SJosh Poimboeuf 382442f04c3SJosh Poimboeuf for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) { 383442f04c3SJosh Poimboeuf rela = malloc(sizeof(*rela)); 384442f04c3SJosh Poimboeuf if (!rela) { 385442f04c3SJosh Poimboeuf perror("malloc"); 386442f04c3SJosh Poimboeuf return -1; 387442f04c3SJosh Poimboeuf } 388442f04c3SJosh Poimboeuf memset(rela, 0, sizeof(*rela)); 389442f04c3SJosh Poimboeuf 390baa41469SJosh Poimboeuf if (!gelf_getrela(sec->data, i, &rela->rela)) { 391baa41469SJosh Poimboeuf WARN_ELF("gelf_getrela"); 392442f04c3SJosh Poimboeuf return -1; 393442f04c3SJosh Poimboeuf } 394442f04c3SJosh Poimboeuf 395442f04c3SJosh Poimboeuf rela->type = GELF_R_TYPE(rela->rela.r_info); 396442f04c3SJosh Poimboeuf rela->addend = rela->rela.r_addend; 397442f04c3SJosh Poimboeuf rela->offset = rela->rela.r_offset; 398442f04c3SJosh Poimboeuf symndx = GELF_R_SYM(rela->rela.r_info); 399442f04c3SJosh Poimboeuf rela->sym = find_symbol_by_index(elf, symndx); 4004a60aa05SAllan Xavier rela->rela_sec = sec; 401442f04c3SJosh Poimboeuf if (!rela->sym) { 402442f04c3SJosh Poimboeuf WARN("can't find rela entry symbol %d for %s", 403442f04c3SJosh Poimboeuf symndx, sec->name); 404442f04c3SJosh Poimboeuf return -1; 405442f04c3SJosh Poimboeuf } 406042ba73fSJosh Poimboeuf 407042ba73fSJosh Poimboeuf list_add_tail(&rela->list, &sec->rela_list); 408042ba73fSJosh Poimboeuf hash_add(sec->rela_hash, &rela->hash, rela->offset); 409042ba73fSJosh Poimboeuf 410442f04c3SJosh Poimboeuf } 411442f04c3SJosh Poimboeuf } 412442f04c3SJosh Poimboeuf 413442f04c3SJosh Poimboeuf return 0; 414442f04c3SJosh Poimboeuf } 415442f04c3SJosh Poimboeuf 416627fce14SJosh Poimboeuf struct elf *elf_open(const char *name, int flags) 417442f04c3SJosh Poimboeuf { 418442f04c3SJosh Poimboeuf struct elf *elf; 419627fce14SJosh Poimboeuf Elf_Cmd cmd; 420442f04c3SJosh Poimboeuf 421442f04c3SJosh Poimboeuf elf_version(EV_CURRENT); 422442f04c3SJosh Poimboeuf 423442f04c3SJosh Poimboeuf elf = malloc(sizeof(*elf)); 424442f04c3SJosh Poimboeuf if (!elf) { 425442f04c3SJosh Poimboeuf perror("malloc"); 426442f04c3SJosh Poimboeuf return NULL; 427442f04c3SJosh Poimboeuf } 428442f04c3SJosh Poimboeuf memset(elf, 0, sizeof(*elf)); 429442f04c3SJosh Poimboeuf 430442f04c3SJosh Poimboeuf INIT_LIST_HEAD(&elf->sections); 431442f04c3SJosh Poimboeuf 432627fce14SJosh Poimboeuf elf->fd = open(name, flags); 433442f04c3SJosh Poimboeuf if (elf->fd == -1) { 434385d11b1SJosh Poimboeuf fprintf(stderr, "objtool: Can't open '%s': %s\n", 435385d11b1SJosh Poimboeuf name, strerror(errno)); 436442f04c3SJosh Poimboeuf goto err; 437442f04c3SJosh Poimboeuf } 438442f04c3SJosh Poimboeuf 439627fce14SJosh Poimboeuf if ((flags & O_ACCMODE) == O_RDONLY) 440627fce14SJosh Poimboeuf cmd = ELF_C_READ_MMAP; 441627fce14SJosh Poimboeuf else if ((flags & O_ACCMODE) == O_RDWR) 442627fce14SJosh Poimboeuf cmd = ELF_C_RDWR; 443627fce14SJosh Poimboeuf else /* O_WRONLY */ 444627fce14SJosh Poimboeuf cmd = ELF_C_WRITE; 445627fce14SJosh Poimboeuf 446627fce14SJosh Poimboeuf elf->elf = elf_begin(elf->fd, cmd, NULL); 447442f04c3SJosh Poimboeuf if (!elf->elf) { 448baa41469SJosh Poimboeuf WARN_ELF("elf_begin"); 449442f04c3SJosh Poimboeuf goto err; 450442f04c3SJosh Poimboeuf } 451442f04c3SJosh Poimboeuf 452442f04c3SJosh Poimboeuf if (!gelf_getehdr(elf->elf, &elf->ehdr)) { 453baa41469SJosh Poimboeuf WARN_ELF("gelf_getehdr"); 454442f04c3SJosh Poimboeuf goto err; 455442f04c3SJosh Poimboeuf } 456442f04c3SJosh Poimboeuf 457442f04c3SJosh Poimboeuf if (read_sections(elf)) 458442f04c3SJosh Poimboeuf goto err; 459442f04c3SJosh Poimboeuf 460442f04c3SJosh Poimboeuf if (read_symbols(elf)) 461442f04c3SJosh Poimboeuf goto err; 462442f04c3SJosh Poimboeuf 463442f04c3SJosh Poimboeuf if (read_relas(elf)) 464442f04c3SJosh Poimboeuf goto err; 465442f04c3SJosh Poimboeuf 466442f04c3SJosh Poimboeuf return elf; 467442f04c3SJosh Poimboeuf 468442f04c3SJosh Poimboeuf err: 469442f04c3SJosh Poimboeuf elf_close(elf); 470442f04c3SJosh Poimboeuf return NULL; 471442f04c3SJosh Poimboeuf } 472442f04c3SJosh Poimboeuf 473627fce14SJosh Poimboeuf struct section *elf_create_section(struct elf *elf, const char *name, 474627fce14SJosh Poimboeuf size_t entsize, int nr) 475627fce14SJosh Poimboeuf { 476627fce14SJosh Poimboeuf struct section *sec, *shstrtab; 477627fce14SJosh Poimboeuf size_t size = entsize * nr; 478627fce14SJosh Poimboeuf struct Elf_Scn *s; 479627fce14SJosh Poimboeuf Elf_Data *data; 480627fce14SJosh Poimboeuf 481627fce14SJosh Poimboeuf sec = malloc(sizeof(*sec)); 482627fce14SJosh Poimboeuf if (!sec) { 483627fce14SJosh Poimboeuf perror("malloc"); 484627fce14SJosh Poimboeuf return NULL; 485627fce14SJosh Poimboeuf } 486627fce14SJosh Poimboeuf memset(sec, 0, sizeof(*sec)); 487627fce14SJosh Poimboeuf 488627fce14SJosh Poimboeuf INIT_LIST_HEAD(&sec->symbol_list); 489627fce14SJosh Poimboeuf INIT_LIST_HEAD(&sec->rela_list); 490627fce14SJosh Poimboeuf hash_init(sec->rela_hash); 491627fce14SJosh Poimboeuf hash_init(sec->symbol_hash); 492627fce14SJosh Poimboeuf 493627fce14SJosh Poimboeuf list_add_tail(&sec->list, &elf->sections); 494627fce14SJosh Poimboeuf 495627fce14SJosh Poimboeuf s = elf_newscn(elf->elf); 496627fce14SJosh Poimboeuf if (!s) { 497627fce14SJosh Poimboeuf WARN_ELF("elf_newscn"); 498627fce14SJosh Poimboeuf return NULL; 499627fce14SJosh Poimboeuf } 500627fce14SJosh Poimboeuf 501627fce14SJosh Poimboeuf sec->name = strdup(name); 502627fce14SJosh Poimboeuf if (!sec->name) { 503627fce14SJosh Poimboeuf perror("strdup"); 504627fce14SJosh Poimboeuf return NULL; 505627fce14SJosh Poimboeuf } 506627fce14SJosh Poimboeuf 507627fce14SJosh Poimboeuf sec->idx = elf_ndxscn(s); 508627fce14SJosh Poimboeuf sec->len = size; 509627fce14SJosh Poimboeuf sec->changed = true; 510627fce14SJosh Poimboeuf 511627fce14SJosh Poimboeuf sec->data = elf_newdata(s); 512627fce14SJosh Poimboeuf if (!sec->data) { 513627fce14SJosh Poimboeuf WARN_ELF("elf_newdata"); 514627fce14SJosh Poimboeuf return NULL; 515627fce14SJosh Poimboeuf } 516627fce14SJosh Poimboeuf 517627fce14SJosh Poimboeuf sec->data->d_size = size; 518627fce14SJosh Poimboeuf sec->data->d_align = 1; 519627fce14SJosh Poimboeuf 520627fce14SJosh Poimboeuf if (size) { 521627fce14SJosh Poimboeuf sec->data->d_buf = malloc(size); 522627fce14SJosh Poimboeuf if (!sec->data->d_buf) { 523627fce14SJosh Poimboeuf perror("malloc"); 524627fce14SJosh Poimboeuf return NULL; 525627fce14SJosh Poimboeuf } 526627fce14SJosh Poimboeuf memset(sec->data->d_buf, 0, size); 527627fce14SJosh Poimboeuf } 528627fce14SJosh Poimboeuf 529627fce14SJosh Poimboeuf if (!gelf_getshdr(s, &sec->sh)) { 530627fce14SJosh Poimboeuf WARN_ELF("gelf_getshdr"); 531627fce14SJosh Poimboeuf return NULL; 532627fce14SJosh Poimboeuf } 533627fce14SJosh Poimboeuf 534627fce14SJosh Poimboeuf sec->sh.sh_size = size; 535627fce14SJosh Poimboeuf sec->sh.sh_entsize = entsize; 536627fce14SJosh Poimboeuf sec->sh.sh_type = SHT_PROGBITS; 537627fce14SJosh Poimboeuf sec->sh.sh_addralign = 1; 538627fce14SJosh Poimboeuf sec->sh.sh_flags = SHF_ALLOC; 539627fce14SJosh Poimboeuf 540627fce14SJosh Poimboeuf 5416d77d3b4SSimon Ser /* Add section name to .shstrtab (or .strtab for Clang) */ 542627fce14SJosh Poimboeuf shstrtab = find_section_by_name(elf, ".shstrtab"); 5436d77d3b4SSimon Ser if (!shstrtab) 5446d77d3b4SSimon Ser shstrtab = find_section_by_name(elf, ".strtab"); 545627fce14SJosh Poimboeuf if (!shstrtab) { 5466d77d3b4SSimon Ser WARN("can't find .shstrtab or .strtab section"); 547627fce14SJosh Poimboeuf return NULL; 548627fce14SJosh Poimboeuf } 549627fce14SJosh Poimboeuf 550627fce14SJosh Poimboeuf s = elf_getscn(elf->elf, shstrtab->idx); 551627fce14SJosh Poimboeuf if (!s) { 552627fce14SJosh Poimboeuf WARN_ELF("elf_getscn"); 553627fce14SJosh Poimboeuf return NULL; 554627fce14SJosh Poimboeuf } 555627fce14SJosh Poimboeuf 556627fce14SJosh Poimboeuf data = elf_newdata(s); 557627fce14SJosh Poimboeuf if (!data) { 558627fce14SJosh Poimboeuf WARN_ELF("elf_newdata"); 559627fce14SJosh Poimboeuf return NULL; 560627fce14SJosh Poimboeuf } 561627fce14SJosh Poimboeuf 562627fce14SJosh Poimboeuf data->d_buf = sec->name; 563627fce14SJosh Poimboeuf data->d_size = strlen(name) + 1; 564627fce14SJosh Poimboeuf data->d_align = 1; 565627fce14SJosh Poimboeuf 566627fce14SJosh Poimboeuf sec->sh.sh_name = shstrtab->len; 567627fce14SJosh Poimboeuf 568627fce14SJosh Poimboeuf shstrtab->len += strlen(name) + 1; 569627fce14SJosh Poimboeuf shstrtab->changed = true; 570627fce14SJosh Poimboeuf 571627fce14SJosh Poimboeuf return sec; 572627fce14SJosh Poimboeuf } 573627fce14SJosh Poimboeuf 574627fce14SJosh Poimboeuf struct section *elf_create_rela_section(struct elf *elf, struct section *base) 575627fce14SJosh Poimboeuf { 576627fce14SJosh Poimboeuf char *relaname; 577627fce14SJosh Poimboeuf struct section *sec; 578627fce14SJosh Poimboeuf 579627fce14SJosh Poimboeuf relaname = malloc(strlen(base->name) + strlen(".rela") + 1); 580627fce14SJosh Poimboeuf if (!relaname) { 581627fce14SJosh Poimboeuf perror("malloc"); 582627fce14SJosh Poimboeuf return NULL; 583627fce14SJosh Poimboeuf } 584627fce14SJosh Poimboeuf strcpy(relaname, ".rela"); 585627fce14SJosh Poimboeuf strcat(relaname, base->name); 586627fce14SJosh Poimboeuf 587627fce14SJosh Poimboeuf sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0); 5880998b7a0SMartin Kepplinger free(relaname); 589627fce14SJosh Poimboeuf if (!sec) 590627fce14SJosh Poimboeuf return NULL; 591627fce14SJosh Poimboeuf 592627fce14SJosh Poimboeuf base->rela = sec; 593627fce14SJosh Poimboeuf sec->base = base; 594627fce14SJosh Poimboeuf 595627fce14SJosh Poimboeuf sec->sh.sh_type = SHT_RELA; 596627fce14SJosh Poimboeuf sec->sh.sh_addralign = 8; 597627fce14SJosh Poimboeuf sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx; 598627fce14SJosh Poimboeuf sec->sh.sh_info = base->idx; 599627fce14SJosh Poimboeuf sec->sh.sh_flags = SHF_INFO_LINK; 600627fce14SJosh Poimboeuf 601627fce14SJosh Poimboeuf return sec; 602627fce14SJosh Poimboeuf } 603627fce14SJosh Poimboeuf 604627fce14SJosh Poimboeuf int elf_rebuild_rela_section(struct section *sec) 605627fce14SJosh Poimboeuf { 606627fce14SJosh Poimboeuf struct rela *rela; 607627fce14SJosh Poimboeuf int nr, idx = 0, size; 608627fce14SJosh Poimboeuf GElf_Rela *relas; 609627fce14SJosh Poimboeuf 610627fce14SJosh Poimboeuf nr = 0; 611627fce14SJosh Poimboeuf list_for_each_entry(rela, &sec->rela_list, list) 612627fce14SJosh Poimboeuf nr++; 613627fce14SJosh Poimboeuf 614627fce14SJosh Poimboeuf size = nr * sizeof(*relas); 615627fce14SJosh Poimboeuf relas = malloc(size); 616627fce14SJosh Poimboeuf if (!relas) { 617627fce14SJosh Poimboeuf perror("malloc"); 618627fce14SJosh Poimboeuf return -1; 619627fce14SJosh Poimboeuf } 620627fce14SJosh Poimboeuf 621627fce14SJosh Poimboeuf sec->data->d_buf = relas; 622627fce14SJosh Poimboeuf sec->data->d_size = size; 623627fce14SJosh Poimboeuf 624627fce14SJosh Poimboeuf sec->sh.sh_size = size; 625627fce14SJosh Poimboeuf 626627fce14SJosh Poimboeuf idx = 0; 627627fce14SJosh Poimboeuf list_for_each_entry(rela, &sec->rela_list, list) { 628627fce14SJosh Poimboeuf relas[idx].r_offset = rela->offset; 629627fce14SJosh Poimboeuf relas[idx].r_addend = rela->addend; 630627fce14SJosh Poimboeuf relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type); 631627fce14SJosh Poimboeuf idx++; 632627fce14SJosh Poimboeuf } 633627fce14SJosh Poimboeuf 634627fce14SJosh Poimboeuf return 0; 635627fce14SJosh Poimboeuf } 636627fce14SJosh Poimboeuf 637627fce14SJosh Poimboeuf int elf_write(struct elf *elf) 638627fce14SJosh Poimboeuf { 639627fce14SJosh Poimboeuf struct section *sec; 640627fce14SJosh Poimboeuf Elf_Scn *s; 641627fce14SJosh Poimboeuf 64297dab2aeSJosh Poimboeuf /* Update section headers for changed sections: */ 643627fce14SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 644627fce14SJosh Poimboeuf if (sec->changed) { 645627fce14SJosh Poimboeuf s = elf_getscn(elf->elf, sec->idx); 646627fce14SJosh Poimboeuf if (!s) { 647627fce14SJosh Poimboeuf WARN_ELF("elf_getscn"); 648627fce14SJosh Poimboeuf return -1; 649627fce14SJosh Poimboeuf } 650627fce14SJosh Poimboeuf if (!gelf_update_shdr(s, &sec->sh)) { 651627fce14SJosh Poimboeuf WARN_ELF("gelf_update_shdr"); 652627fce14SJosh Poimboeuf return -1; 653627fce14SJosh Poimboeuf } 654627fce14SJosh Poimboeuf } 655627fce14SJosh Poimboeuf } 656627fce14SJosh Poimboeuf 65797dab2aeSJosh Poimboeuf /* Make sure the new section header entries get updated properly. */ 65897dab2aeSJosh Poimboeuf elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY); 65997dab2aeSJosh Poimboeuf 66097dab2aeSJosh Poimboeuf /* Write all changes to the file. */ 661627fce14SJosh Poimboeuf if (elf_update(elf->elf, ELF_C_WRITE) < 0) { 662627fce14SJosh Poimboeuf WARN_ELF("elf_update"); 663627fce14SJosh Poimboeuf return -1; 664627fce14SJosh Poimboeuf } 665627fce14SJosh Poimboeuf 666627fce14SJosh Poimboeuf return 0; 667627fce14SJosh Poimboeuf } 668627fce14SJosh Poimboeuf 669442f04c3SJosh Poimboeuf void elf_close(struct elf *elf) 670442f04c3SJosh Poimboeuf { 671442f04c3SJosh Poimboeuf struct section *sec, *tmpsec; 672442f04c3SJosh Poimboeuf struct symbol *sym, *tmpsym; 673442f04c3SJosh Poimboeuf struct rela *rela, *tmprela; 674442f04c3SJosh Poimboeuf 675baa41469SJosh Poimboeuf if (elf->elf) 676baa41469SJosh Poimboeuf elf_end(elf->elf); 677baa41469SJosh Poimboeuf 678baa41469SJosh Poimboeuf if (elf->fd > 0) 679baa41469SJosh Poimboeuf close(elf->fd); 680baa41469SJosh Poimboeuf 681442f04c3SJosh Poimboeuf list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) { 682a196e171SJosh Poimboeuf list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) { 683442f04c3SJosh Poimboeuf list_del(&sym->list); 684042ba73fSJosh Poimboeuf hash_del(&sym->hash); 685442f04c3SJosh Poimboeuf free(sym); 686442f04c3SJosh Poimboeuf } 687a196e171SJosh Poimboeuf list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) { 688442f04c3SJosh Poimboeuf list_del(&rela->list); 689042ba73fSJosh Poimboeuf hash_del(&rela->hash); 690442f04c3SJosh Poimboeuf free(rela); 691442f04c3SJosh Poimboeuf } 692442f04c3SJosh Poimboeuf list_del(&sec->list); 693442f04c3SJosh Poimboeuf free(sec); 694442f04c3SJosh Poimboeuf } 695baa41469SJosh Poimboeuf 696442f04c3SJosh Poimboeuf free(elf); 697442f04c3SJosh Poimboeuf } 698