11ccea77eSThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later 2442f04c3SJosh Poimboeuf /* 3442f04c3SJosh Poimboeuf * elf.c - ELF access library 4442f04c3SJosh Poimboeuf * 5442f04c3SJosh Poimboeuf * Adapted from kpatch (https://github.com/dynup/kpatch): 6442f04c3SJosh Poimboeuf * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com> 7442f04c3SJosh Poimboeuf * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> 8442f04c3SJosh Poimboeuf */ 9442f04c3SJosh Poimboeuf 10442f04c3SJosh Poimboeuf #include <sys/types.h> 11442f04c3SJosh Poimboeuf #include <sys/stat.h> 12442f04c3SJosh Poimboeuf #include <fcntl.h> 13442f04c3SJosh Poimboeuf #include <stdio.h> 14442f04c3SJosh Poimboeuf #include <stdlib.h> 15442f04c3SJosh Poimboeuf #include <string.h> 16442f04c3SJosh Poimboeuf #include <unistd.h> 17385d11b1SJosh Poimboeuf #include <errno.h> 18442f04c3SJosh Poimboeuf 19442f04c3SJosh Poimboeuf #include "elf.h" 20442f04c3SJosh Poimboeuf #include "warn.h" 21442f04c3SJosh Poimboeuf 2222566c16SArtem Savkov #define MAX_NAME_LEN 128 2322566c16SArtem Savkov 24442f04c3SJosh Poimboeuf struct section *find_section_by_name(struct elf *elf, const char *name) 25442f04c3SJosh Poimboeuf { 26442f04c3SJosh Poimboeuf struct section *sec; 27442f04c3SJosh Poimboeuf 28442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 29442f04c3SJosh Poimboeuf if (!strcmp(sec->name, name)) 30442f04c3SJosh Poimboeuf return sec; 31442f04c3SJosh Poimboeuf 32442f04c3SJosh Poimboeuf return NULL; 33442f04c3SJosh Poimboeuf } 34442f04c3SJosh Poimboeuf 35442f04c3SJosh Poimboeuf static struct section *find_section_by_index(struct elf *elf, 36442f04c3SJosh Poimboeuf unsigned int idx) 37442f04c3SJosh Poimboeuf { 38442f04c3SJosh Poimboeuf struct section *sec; 39442f04c3SJosh Poimboeuf 40442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 41442f04c3SJosh Poimboeuf if (sec->idx == idx) 42442f04c3SJosh Poimboeuf return sec; 43442f04c3SJosh Poimboeuf 44442f04c3SJosh Poimboeuf return NULL; 45442f04c3SJosh Poimboeuf } 46442f04c3SJosh Poimboeuf 47442f04c3SJosh Poimboeuf static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx) 48442f04c3SJosh Poimboeuf { 49442f04c3SJosh Poimboeuf struct section *sec; 50442f04c3SJosh Poimboeuf struct symbol *sym; 51442f04c3SJosh Poimboeuf 52442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 53042ba73fSJosh Poimboeuf hash_for_each_possible(sec->symbol_hash, sym, hash, idx) 54442f04c3SJosh Poimboeuf if (sym->idx == idx) 55442f04c3SJosh Poimboeuf return sym; 56442f04c3SJosh Poimboeuf 57442f04c3SJosh Poimboeuf return NULL; 58442f04c3SJosh Poimboeuf } 59442f04c3SJosh Poimboeuf 60442f04c3SJosh Poimboeuf struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset) 61442f04c3SJosh Poimboeuf { 62442f04c3SJosh Poimboeuf struct symbol *sym; 63442f04c3SJosh Poimboeuf 64a196e171SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 65442f04c3SJosh Poimboeuf if (sym->type != STT_SECTION && 66442f04c3SJosh Poimboeuf sym->offset == offset) 67442f04c3SJosh Poimboeuf return sym; 68442f04c3SJosh Poimboeuf 69442f04c3SJosh Poimboeuf return NULL; 70442f04c3SJosh Poimboeuf } 71442f04c3SJosh Poimboeuf 7213810435SJosh Poimboeuf struct symbol *find_symbol_by_name(struct elf *elf, const char *name) 7313810435SJosh Poimboeuf { 7413810435SJosh Poimboeuf struct section *sec; 7513810435SJosh Poimboeuf struct symbol *sym; 7613810435SJosh Poimboeuf 7713810435SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 7813810435SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 7913810435SJosh Poimboeuf if (!strcmp(sym->name, name)) 8013810435SJosh Poimboeuf return sym; 8113810435SJosh Poimboeuf 8213810435SJosh Poimboeuf return NULL; 8313810435SJosh Poimboeuf } 8413810435SJosh Poimboeuf 855c51f4aeSJosh Poimboeuf struct symbol *find_symbol_containing(struct section *sec, unsigned long offset) 865c51f4aeSJosh Poimboeuf { 875c51f4aeSJosh Poimboeuf struct symbol *sym; 885c51f4aeSJosh Poimboeuf 895c51f4aeSJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 905c51f4aeSJosh Poimboeuf if (sym->type != STT_SECTION && 915c51f4aeSJosh Poimboeuf offset >= sym->offset && offset < sym->offset + sym->len) 925c51f4aeSJosh Poimboeuf return sym; 935c51f4aeSJosh Poimboeuf 945c51f4aeSJosh Poimboeuf return NULL; 955c51f4aeSJosh Poimboeuf } 965c51f4aeSJosh Poimboeuf 97442f04c3SJosh Poimboeuf struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, 98442f04c3SJosh Poimboeuf unsigned int len) 99442f04c3SJosh Poimboeuf { 100442f04c3SJosh Poimboeuf struct rela *rela; 101042ba73fSJosh Poimboeuf unsigned long o; 102442f04c3SJosh Poimboeuf 103442f04c3SJosh Poimboeuf if (!sec->rela) 104442f04c3SJosh Poimboeuf return NULL; 105442f04c3SJosh Poimboeuf 106042ba73fSJosh Poimboeuf for (o = offset; o < offset + len; o++) 107042ba73fSJosh Poimboeuf hash_for_each_possible(sec->rela->rela_hash, rela, hash, o) 108042ba73fSJosh Poimboeuf if (rela->offset == o) 109442f04c3SJosh Poimboeuf return rela; 110442f04c3SJosh Poimboeuf 111442f04c3SJosh Poimboeuf return NULL; 112442f04c3SJosh Poimboeuf } 113442f04c3SJosh Poimboeuf 114442f04c3SJosh Poimboeuf struct rela *find_rela_by_dest(struct section *sec, unsigned long offset) 115442f04c3SJosh Poimboeuf { 116442f04c3SJosh Poimboeuf return find_rela_by_dest_range(sec, offset, 1); 117442f04c3SJosh Poimboeuf } 118442f04c3SJosh Poimboeuf 119442f04c3SJosh Poimboeuf struct symbol *find_containing_func(struct section *sec, unsigned long offset) 120442f04c3SJosh Poimboeuf { 121442f04c3SJosh Poimboeuf struct symbol *func; 122442f04c3SJosh Poimboeuf 123a196e171SJosh Poimboeuf list_for_each_entry(func, &sec->symbol_list, list) 124442f04c3SJosh Poimboeuf if (func->type == STT_FUNC && offset >= func->offset && 125442f04c3SJosh Poimboeuf offset < func->offset + func->len) 126442f04c3SJosh Poimboeuf return func; 127442f04c3SJosh Poimboeuf 128442f04c3SJosh Poimboeuf return NULL; 129442f04c3SJosh Poimboeuf } 130442f04c3SJosh Poimboeuf 131442f04c3SJosh Poimboeuf static int read_sections(struct elf *elf) 132442f04c3SJosh Poimboeuf { 133442f04c3SJosh Poimboeuf Elf_Scn *s = NULL; 134442f04c3SJosh Poimboeuf struct section *sec; 135442f04c3SJosh Poimboeuf size_t shstrndx, sections_nr; 136442f04c3SJosh Poimboeuf int i; 137442f04c3SJosh Poimboeuf 138442f04c3SJosh Poimboeuf if (elf_getshdrnum(elf->elf, §ions_nr)) { 139baa41469SJosh Poimboeuf WARN_ELF("elf_getshdrnum"); 140442f04c3SJosh Poimboeuf return -1; 141442f04c3SJosh Poimboeuf } 142442f04c3SJosh Poimboeuf 143442f04c3SJosh Poimboeuf if (elf_getshdrstrndx(elf->elf, &shstrndx)) { 144baa41469SJosh Poimboeuf WARN_ELF("elf_getshdrstrndx"); 145442f04c3SJosh Poimboeuf return -1; 146442f04c3SJosh Poimboeuf } 147442f04c3SJosh Poimboeuf 148442f04c3SJosh Poimboeuf for (i = 0; i < sections_nr; i++) { 149442f04c3SJosh Poimboeuf sec = malloc(sizeof(*sec)); 150442f04c3SJosh Poimboeuf if (!sec) { 151442f04c3SJosh Poimboeuf perror("malloc"); 152442f04c3SJosh Poimboeuf return -1; 153442f04c3SJosh Poimboeuf } 154442f04c3SJosh Poimboeuf memset(sec, 0, sizeof(*sec)); 155442f04c3SJosh Poimboeuf 156a196e171SJosh Poimboeuf INIT_LIST_HEAD(&sec->symbol_list); 157a196e171SJosh Poimboeuf INIT_LIST_HEAD(&sec->rela_list); 158042ba73fSJosh Poimboeuf hash_init(sec->rela_hash); 159042ba73fSJosh Poimboeuf hash_init(sec->symbol_hash); 160442f04c3SJosh Poimboeuf 161442f04c3SJosh Poimboeuf list_add_tail(&sec->list, &elf->sections); 162442f04c3SJosh Poimboeuf 163442f04c3SJosh Poimboeuf s = elf_getscn(elf->elf, i); 164442f04c3SJosh Poimboeuf if (!s) { 165baa41469SJosh Poimboeuf WARN_ELF("elf_getscn"); 166442f04c3SJosh Poimboeuf return -1; 167442f04c3SJosh Poimboeuf } 168442f04c3SJosh Poimboeuf 169442f04c3SJosh Poimboeuf sec->idx = elf_ndxscn(s); 170442f04c3SJosh Poimboeuf 171442f04c3SJosh Poimboeuf if (!gelf_getshdr(s, &sec->sh)) { 172baa41469SJosh Poimboeuf WARN_ELF("gelf_getshdr"); 173442f04c3SJosh Poimboeuf return -1; 174442f04c3SJosh Poimboeuf } 175442f04c3SJosh Poimboeuf 176442f04c3SJosh Poimboeuf sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name); 177442f04c3SJosh Poimboeuf if (!sec->name) { 178baa41469SJosh Poimboeuf WARN_ELF("elf_strptr"); 179442f04c3SJosh Poimboeuf return -1; 180442f04c3SJosh Poimboeuf } 181442f04c3SJosh Poimboeuf 182df968c93SPetr Vandrovec if (sec->sh.sh_size != 0) { 183baa41469SJosh Poimboeuf sec->data = elf_getdata(s, NULL); 184baa41469SJosh Poimboeuf if (!sec->data) { 185baa41469SJosh Poimboeuf WARN_ELF("elf_getdata"); 186442f04c3SJosh Poimboeuf return -1; 187442f04c3SJosh Poimboeuf } 188baa41469SJosh Poimboeuf if (sec->data->d_off != 0 || 189baa41469SJosh Poimboeuf sec->data->d_size != sec->sh.sh_size) { 190df968c93SPetr Vandrovec WARN("unexpected data attributes for %s", 191df968c93SPetr Vandrovec sec->name); 192442f04c3SJosh Poimboeuf return -1; 193442f04c3SJosh Poimboeuf } 194df968c93SPetr Vandrovec } 195df968c93SPetr Vandrovec sec->len = sec->sh.sh_size; 196442f04c3SJosh Poimboeuf } 197442f04c3SJosh Poimboeuf 198442f04c3SJosh Poimboeuf /* sanity check, one more call to elf_nextscn() should return NULL */ 199442f04c3SJosh Poimboeuf if (elf_nextscn(elf->elf, s)) { 200442f04c3SJosh Poimboeuf WARN("section entry mismatch"); 201442f04c3SJosh Poimboeuf return -1; 202442f04c3SJosh Poimboeuf } 203442f04c3SJosh Poimboeuf 204442f04c3SJosh Poimboeuf return 0; 205442f04c3SJosh Poimboeuf } 206442f04c3SJosh Poimboeuf 207442f04c3SJosh Poimboeuf static int read_symbols(struct elf *elf) 208442f04c3SJosh Poimboeuf { 20913810435SJosh Poimboeuf struct section *symtab, *sec; 21009f30d83SPeter Zijlstra struct symbol *sym, *pfunc, *alias; 211442f04c3SJosh Poimboeuf struct list_head *entry, *tmp; 212442f04c3SJosh Poimboeuf int symbols_nr, i; 21313810435SJosh Poimboeuf char *coldstr; 214442f04c3SJosh Poimboeuf 215442f04c3SJosh Poimboeuf symtab = find_section_by_name(elf, ".symtab"); 216442f04c3SJosh Poimboeuf if (!symtab) { 217442f04c3SJosh Poimboeuf WARN("missing symbol table"); 218442f04c3SJosh Poimboeuf return -1; 219442f04c3SJosh Poimboeuf } 220442f04c3SJosh Poimboeuf 221442f04c3SJosh Poimboeuf symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize; 222442f04c3SJosh Poimboeuf 223442f04c3SJosh Poimboeuf for (i = 0; i < symbols_nr; i++) { 224442f04c3SJosh Poimboeuf sym = malloc(sizeof(*sym)); 225442f04c3SJosh Poimboeuf if (!sym) { 226442f04c3SJosh Poimboeuf perror("malloc"); 227442f04c3SJosh Poimboeuf return -1; 228442f04c3SJosh Poimboeuf } 229442f04c3SJosh Poimboeuf memset(sym, 0, sizeof(*sym)); 23009f30d83SPeter Zijlstra alias = sym; 231442f04c3SJosh Poimboeuf 232442f04c3SJosh Poimboeuf sym->idx = i; 233442f04c3SJosh Poimboeuf 234baa41469SJosh Poimboeuf if (!gelf_getsym(symtab->data, i, &sym->sym)) { 235baa41469SJosh Poimboeuf WARN_ELF("gelf_getsym"); 236442f04c3SJosh Poimboeuf goto err; 237442f04c3SJosh Poimboeuf } 238442f04c3SJosh Poimboeuf 239442f04c3SJosh Poimboeuf sym->name = elf_strptr(elf->elf, symtab->sh.sh_link, 240442f04c3SJosh Poimboeuf sym->sym.st_name); 241442f04c3SJosh Poimboeuf if (!sym->name) { 242baa41469SJosh Poimboeuf WARN_ELF("elf_strptr"); 243442f04c3SJosh Poimboeuf goto err; 244442f04c3SJosh Poimboeuf } 245442f04c3SJosh Poimboeuf 246442f04c3SJosh Poimboeuf sym->type = GELF_ST_TYPE(sym->sym.st_info); 247442f04c3SJosh Poimboeuf sym->bind = GELF_ST_BIND(sym->sym.st_info); 248442f04c3SJosh Poimboeuf 249442f04c3SJosh Poimboeuf if (sym->sym.st_shndx > SHN_UNDEF && 250442f04c3SJosh Poimboeuf sym->sym.st_shndx < SHN_LORESERVE) { 251442f04c3SJosh Poimboeuf sym->sec = find_section_by_index(elf, 252442f04c3SJosh Poimboeuf sym->sym.st_shndx); 253442f04c3SJosh Poimboeuf if (!sym->sec) { 254442f04c3SJosh Poimboeuf WARN("couldn't find section for symbol %s", 255442f04c3SJosh Poimboeuf sym->name); 256442f04c3SJosh Poimboeuf goto err; 257442f04c3SJosh Poimboeuf } 258442f04c3SJosh Poimboeuf if (sym->type == STT_SECTION) { 259442f04c3SJosh Poimboeuf sym->name = sym->sec->name; 260442f04c3SJosh Poimboeuf sym->sec->sym = sym; 261442f04c3SJosh Poimboeuf } 262442f04c3SJosh Poimboeuf } else 263442f04c3SJosh Poimboeuf sym->sec = find_section_by_index(elf, 0); 264442f04c3SJosh Poimboeuf 265442f04c3SJosh Poimboeuf sym->offset = sym->sym.st_value; 266442f04c3SJosh Poimboeuf sym->len = sym->sym.st_size; 267442f04c3SJosh Poimboeuf 268442f04c3SJosh Poimboeuf /* sorted insert into a per-section list */ 269a196e171SJosh Poimboeuf entry = &sym->sec->symbol_list; 270a196e171SJosh Poimboeuf list_for_each_prev(tmp, &sym->sec->symbol_list) { 271442f04c3SJosh Poimboeuf struct symbol *s; 272442f04c3SJosh Poimboeuf 273442f04c3SJosh Poimboeuf s = list_entry(tmp, struct symbol, list); 274442f04c3SJosh Poimboeuf 275442f04c3SJosh Poimboeuf if (sym->offset > s->offset) { 276442f04c3SJosh Poimboeuf entry = tmp; 277442f04c3SJosh Poimboeuf break; 278442f04c3SJosh Poimboeuf } 279442f04c3SJosh Poimboeuf 28009f30d83SPeter Zijlstra if (sym->offset == s->offset) { 281e10cd8feSJosh Poimboeuf if (sym->len && sym->len == s->len && alias == sym) 28209f30d83SPeter Zijlstra alias = s; 28309f30d83SPeter Zijlstra 28409f30d83SPeter Zijlstra if (sym->len >= s->len) { 285442f04c3SJosh Poimboeuf entry = tmp; 286442f04c3SJosh Poimboeuf break; 287442f04c3SJosh Poimboeuf } 288442f04c3SJosh Poimboeuf } 28909f30d83SPeter Zijlstra } 29009f30d83SPeter Zijlstra sym->alias = alias; 291442f04c3SJosh Poimboeuf list_add(&sym->list, entry); 292042ba73fSJosh Poimboeuf hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx); 293442f04c3SJosh Poimboeuf } 294442f04c3SJosh Poimboeuf 29513810435SJosh Poimboeuf /* Create parent/child links for any cold subfunctions */ 29613810435SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 29713810435SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) { 29822566c16SArtem Savkov char pname[MAX_NAME_LEN + 1]; 29922566c16SArtem Savkov size_t pnamelen; 30013810435SJosh Poimboeuf if (sym->type != STT_FUNC) 30113810435SJosh Poimboeuf continue; 30213810435SJosh Poimboeuf sym->pfunc = sym->cfunc = sym; 303bcb6fb5dSJosh Poimboeuf coldstr = strstr(sym->name, ".cold"); 30408b393d0SJosh Poimboeuf if (!coldstr) 30508b393d0SJosh Poimboeuf continue; 30608b393d0SJosh Poimboeuf 30722566c16SArtem Savkov pnamelen = coldstr - sym->name; 30822566c16SArtem Savkov if (pnamelen > MAX_NAME_LEN) { 30922566c16SArtem Savkov WARN("%s(): parent function name exceeds maximum length of %d characters", 31022566c16SArtem Savkov sym->name, MAX_NAME_LEN); 31122566c16SArtem Savkov return -1; 31222566c16SArtem Savkov } 31322566c16SArtem Savkov 31422566c16SArtem Savkov strncpy(pname, sym->name, pnamelen); 31522566c16SArtem Savkov pname[pnamelen] = '\0'; 31622566c16SArtem Savkov pfunc = find_symbol_by_name(elf, pname); 31713810435SJosh Poimboeuf 31813810435SJosh Poimboeuf if (!pfunc) { 31913810435SJosh Poimboeuf WARN("%s(): can't find parent function", 32013810435SJosh Poimboeuf sym->name); 3210b9301fbSArtem Savkov return -1; 32213810435SJosh Poimboeuf } 32313810435SJosh Poimboeuf 32413810435SJosh Poimboeuf sym->pfunc = pfunc; 32513810435SJosh Poimboeuf pfunc->cfunc = sym; 32608b393d0SJosh Poimboeuf 32708b393d0SJosh Poimboeuf /* 32808b393d0SJosh Poimboeuf * Unfortunately, -fnoreorder-functions puts the child 32908b393d0SJosh Poimboeuf * inside the parent. Remove the overlap so we can 33008b393d0SJosh Poimboeuf * have sane assumptions. 33108b393d0SJosh Poimboeuf * 33208b393d0SJosh Poimboeuf * Note that pfunc->len now no longer matches 33308b393d0SJosh Poimboeuf * pfunc->sym.st_size. 33408b393d0SJosh Poimboeuf */ 33508b393d0SJosh Poimboeuf if (sym->sec == pfunc->sec && 33608b393d0SJosh Poimboeuf sym->offset >= pfunc->offset && 33708b393d0SJosh Poimboeuf sym->offset + sym->len == pfunc->offset + pfunc->len) { 33808b393d0SJosh Poimboeuf pfunc->len -= sym->len; 33913810435SJosh Poimboeuf } 34013810435SJosh Poimboeuf } 34113810435SJosh Poimboeuf } 34213810435SJosh Poimboeuf 343442f04c3SJosh Poimboeuf return 0; 344442f04c3SJosh Poimboeuf 345442f04c3SJosh Poimboeuf err: 346442f04c3SJosh Poimboeuf free(sym); 347442f04c3SJosh Poimboeuf return -1; 348442f04c3SJosh Poimboeuf } 349442f04c3SJosh Poimboeuf 350442f04c3SJosh Poimboeuf static int read_relas(struct elf *elf) 351442f04c3SJosh Poimboeuf { 352442f04c3SJosh Poimboeuf struct section *sec; 353442f04c3SJosh Poimboeuf struct rela *rela; 354442f04c3SJosh Poimboeuf int i; 355442f04c3SJosh Poimboeuf unsigned int symndx; 356442f04c3SJosh Poimboeuf 357442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 358442f04c3SJosh Poimboeuf if (sec->sh.sh_type != SHT_RELA) 359442f04c3SJosh Poimboeuf continue; 360442f04c3SJosh Poimboeuf 361442f04c3SJosh Poimboeuf sec->base = find_section_by_name(elf, sec->name + 5); 362442f04c3SJosh Poimboeuf if (!sec->base) { 363442f04c3SJosh Poimboeuf WARN("can't find base section for rela section %s", 364442f04c3SJosh Poimboeuf sec->name); 365442f04c3SJosh Poimboeuf return -1; 366442f04c3SJosh Poimboeuf } 367442f04c3SJosh Poimboeuf 368442f04c3SJosh Poimboeuf sec->base->rela = sec; 369442f04c3SJosh Poimboeuf 370442f04c3SJosh Poimboeuf for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) { 371442f04c3SJosh Poimboeuf rela = malloc(sizeof(*rela)); 372442f04c3SJosh Poimboeuf if (!rela) { 373442f04c3SJosh Poimboeuf perror("malloc"); 374442f04c3SJosh Poimboeuf return -1; 375442f04c3SJosh Poimboeuf } 376442f04c3SJosh Poimboeuf memset(rela, 0, sizeof(*rela)); 377442f04c3SJosh Poimboeuf 378baa41469SJosh Poimboeuf if (!gelf_getrela(sec->data, i, &rela->rela)) { 379baa41469SJosh Poimboeuf WARN_ELF("gelf_getrela"); 380442f04c3SJosh Poimboeuf return -1; 381442f04c3SJosh Poimboeuf } 382442f04c3SJosh Poimboeuf 383442f04c3SJosh Poimboeuf rela->type = GELF_R_TYPE(rela->rela.r_info); 384442f04c3SJosh Poimboeuf rela->addend = rela->rela.r_addend; 385442f04c3SJosh Poimboeuf rela->offset = rela->rela.r_offset; 386442f04c3SJosh Poimboeuf symndx = GELF_R_SYM(rela->rela.r_info); 387442f04c3SJosh Poimboeuf rela->sym = find_symbol_by_index(elf, symndx); 3884a60aa05SAllan Xavier rela->rela_sec = sec; 389442f04c3SJosh Poimboeuf if (!rela->sym) { 390442f04c3SJosh Poimboeuf WARN("can't find rela entry symbol %d for %s", 391442f04c3SJosh Poimboeuf symndx, sec->name); 392442f04c3SJosh Poimboeuf return -1; 393442f04c3SJosh Poimboeuf } 394042ba73fSJosh Poimboeuf 395042ba73fSJosh Poimboeuf list_add_tail(&rela->list, &sec->rela_list); 396042ba73fSJosh Poimboeuf hash_add(sec->rela_hash, &rela->hash, rela->offset); 397042ba73fSJosh Poimboeuf 398442f04c3SJosh Poimboeuf } 399442f04c3SJosh Poimboeuf } 400442f04c3SJosh Poimboeuf 401442f04c3SJosh Poimboeuf return 0; 402442f04c3SJosh Poimboeuf } 403442f04c3SJosh Poimboeuf 4048e144797SMichael Forney struct elf *elf_read(const char *name, int flags) 405442f04c3SJosh Poimboeuf { 406442f04c3SJosh Poimboeuf struct elf *elf; 407627fce14SJosh Poimboeuf Elf_Cmd cmd; 408442f04c3SJosh Poimboeuf 409442f04c3SJosh Poimboeuf elf_version(EV_CURRENT); 410442f04c3SJosh Poimboeuf 411442f04c3SJosh Poimboeuf elf = malloc(sizeof(*elf)); 412442f04c3SJosh Poimboeuf if (!elf) { 413442f04c3SJosh Poimboeuf perror("malloc"); 414442f04c3SJosh Poimboeuf return NULL; 415442f04c3SJosh Poimboeuf } 416442f04c3SJosh Poimboeuf memset(elf, 0, sizeof(*elf)); 417442f04c3SJosh Poimboeuf 418442f04c3SJosh Poimboeuf INIT_LIST_HEAD(&elf->sections); 419442f04c3SJosh Poimboeuf 420627fce14SJosh Poimboeuf elf->fd = open(name, flags); 421442f04c3SJosh Poimboeuf if (elf->fd == -1) { 422385d11b1SJosh Poimboeuf fprintf(stderr, "objtool: Can't open '%s': %s\n", 423385d11b1SJosh Poimboeuf name, strerror(errno)); 424442f04c3SJosh Poimboeuf goto err; 425442f04c3SJosh Poimboeuf } 426442f04c3SJosh Poimboeuf 427627fce14SJosh Poimboeuf if ((flags & O_ACCMODE) == O_RDONLY) 428627fce14SJosh Poimboeuf cmd = ELF_C_READ_MMAP; 429627fce14SJosh Poimboeuf else if ((flags & O_ACCMODE) == O_RDWR) 430627fce14SJosh Poimboeuf cmd = ELF_C_RDWR; 431627fce14SJosh Poimboeuf else /* O_WRONLY */ 432627fce14SJosh Poimboeuf cmd = ELF_C_WRITE; 433627fce14SJosh Poimboeuf 434627fce14SJosh Poimboeuf elf->elf = elf_begin(elf->fd, cmd, NULL); 435442f04c3SJosh Poimboeuf if (!elf->elf) { 436baa41469SJosh Poimboeuf WARN_ELF("elf_begin"); 437442f04c3SJosh Poimboeuf goto err; 438442f04c3SJosh Poimboeuf } 439442f04c3SJosh Poimboeuf 440442f04c3SJosh Poimboeuf if (!gelf_getehdr(elf->elf, &elf->ehdr)) { 441baa41469SJosh Poimboeuf WARN_ELF("gelf_getehdr"); 442442f04c3SJosh Poimboeuf goto err; 443442f04c3SJosh Poimboeuf } 444442f04c3SJosh Poimboeuf 445442f04c3SJosh Poimboeuf if (read_sections(elf)) 446442f04c3SJosh Poimboeuf goto err; 447442f04c3SJosh Poimboeuf 448442f04c3SJosh Poimboeuf if (read_symbols(elf)) 449442f04c3SJosh Poimboeuf goto err; 450442f04c3SJosh Poimboeuf 451442f04c3SJosh Poimboeuf if (read_relas(elf)) 452442f04c3SJosh Poimboeuf goto err; 453442f04c3SJosh Poimboeuf 454442f04c3SJosh Poimboeuf return elf; 455442f04c3SJosh Poimboeuf 456442f04c3SJosh Poimboeuf err: 457442f04c3SJosh Poimboeuf elf_close(elf); 458442f04c3SJosh Poimboeuf return NULL; 459442f04c3SJosh Poimboeuf } 460442f04c3SJosh Poimboeuf 461627fce14SJosh Poimboeuf struct section *elf_create_section(struct elf *elf, const char *name, 462627fce14SJosh Poimboeuf size_t entsize, int nr) 463627fce14SJosh Poimboeuf { 464627fce14SJosh Poimboeuf struct section *sec, *shstrtab; 465627fce14SJosh Poimboeuf size_t size = entsize * nr; 4663c3ea503SMichael Forney Elf_Scn *s; 467627fce14SJosh Poimboeuf Elf_Data *data; 468627fce14SJosh Poimboeuf 469627fce14SJosh Poimboeuf sec = malloc(sizeof(*sec)); 470627fce14SJosh Poimboeuf if (!sec) { 471627fce14SJosh Poimboeuf perror("malloc"); 472627fce14SJosh Poimboeuf return NULL; 473627fce14SJosh Poimboeuf } 474627fce14SJosh Poimboeuf memset(sec, 0, sizeof(*sec)); 475627fce14SJosh Poimboeuf 476627fce14SJosh Poimboeuf INIT_LIST_HEAD(&sec->symbol_list); 477627fce14SJosh Poimboeuf INIT_LIST_HEAD(&sec->rela_list); 478627fce14SJosh Poimboeuf hash_init(sec->rela_hash); 479627fce14SJosh Poimboeuf hash_init(sec->symbol_hash); 480627fce14SJosh Poimboeuf 481627fce14SJosh Poimboeuf list_add_tail(&sec->list, &elf->sections); 482627fce14SJosh Poimboeuf 483627fce14SJosh Poimboeuf s = elf_newscn(elf->elf); 484627fce14SJosh Poimboeuf if (!s) { 485627fce14SJosh Poimboeuf WARN_ELF("elf_newscn"); 486627fce14SJosh Poimboeuf return NULL; 487627fce14SJosh Poimboeuf } 488627fce14SJosh Poimboeuf 489627fce14SJosh Poimboeuf sec->name = strdup(name); 490627fce14SJosh Poimboeuf if (!sec->name) { 491627fce14SJosh Poimboeuf perror("strdup"); 492627fce14SJosh Poimboeuf return NULL; 493627fce14SJosh Poimboeuf } 494627fce14SJosh Poimboeuf 495627fce14SJosh Poimboeuf sec->idx = elf_ndxscn(s); 496627fce14SJosh Poimboeuf sec->len = size; 497627fce14SJosh Poimboeuf sec->changed = true; 498627fce14SJosh Poimboeuf 499627fce14SJosh Poimboeuf sec->data = elf_newdata(s); 500627fce14SJosh Poimboeuf if (!sec->data) { 501627fce14SJosh Poimboeuf WARN_ELF("elf_newdata"); 502627fce14SJosh Poimboeuf return NULL; 503627fce14SJosh Poimboeuf } 504627fce14SJosh Poimboeuf 505627fce14SJosh Poimboeuf sec->data->d_size = size; 506627fce14SJosh Poimboeuf sec->data->d_align = 1; 507627fce14SJosh Poimboeuf 508627fce14SJosh Poimboeuf if (size) { 509627fce14SJosh Poimboeuf sec->data->d_buf = malloc(size); 510627fce14SJosh Poimboeuf if (!sec->data->d_buf) { 511627fce14SJosh Poimboeuf perror("malloc"); 512627fce14SJosh Poimboeuf return NULL; 513627fce14SJosh Poimboeuf } 514627fce14SJosh Poimboeuf memset(sec->data->d_buf, 0, size); 515627fce14SJosh Poimboeuf } 516627fce14SJosh Poimboeuf 517627fce14SJosh Poimboeuf if (!gelf_getshdr(s, &sec->sh)) { 518627fce14SJosh Poimboeuf WARN_ELF("gelf_getshdr"); 519627fce14SJosh Poimboeuf return NULL; 520627fce14SJosh Poimboeuf } 521627fce14SJosh Poimboeuf 522627fce14SJosh Poimboeuf sec->sh.sh_size = size; 523627fce14SJosh Poimboeuf sec->sh.sh_entsize = entsize; 524627fce14SJosh Poimboeuf sec->sh.sh_type = SHT_PROGBITS; 525627fce14SJosh Poimboeuf sec->sh.sh_addralign = 1; 526627fce14SJosh Poimboeuf sec->sh.sh_flags = SHF_ALLOC; 527627fce14SJosh Poimboeuf 528627fce14SJosh Poimboeuf 5296d77d3b4SSimon Ser /* Add section name to .shstrtab (or .strtab for Clang) */ 530627fce14SJosh Poimboeuf shstrtab = find_section_by_name(elf, ".shstrtab"); 5316d77d3b4SSimon Ser if (!shstrtab) 5326d77d3b4SSimon Ser shstrtab = find_section_by_name(elf, ".strtab"); 533627fce14SJosh Poimboeuf if (!shstrtab) { 5346d77d3b4SSimon Ser WARN("can't find .shstrtab or .strtab section"); 535627fce14SJosh Poimboeuf return NULL; 536627fce14SJosh Poimboeuf } 537627fce14SJosh Poimboeuf 538627fce14SJosh Poimboeuf s = elf_getscn(elf->elf, shstrtab->idx); 539627fce14SJosh Poimboeuf if (!s) { 540627fce14SJosh Poimboeuf WARN_ELF("elf_getscn"); 541627fce14SJosh Poimboeuf return NULL; 542627fce14SJosh Poimboeuf } 543627fce14SJosh Poimboeuf 544627fce14SJosh Poimboeuf data = elf_newdata(s); 545627fce14SJosh Poimboeuf if (!data) { 546627fce14SJosh Poimboeuf WARN_ELF("elf_newdata"); 547627fce14SJosh Poimboeuf return NULL; 548627fce14SJosh Poimboeuf } 549627fce14SJosh Poimboeuf 550627fce14SJosh Poimboeuf data->d_buf = sec->name; 551627fce14SJosh Poimboeuf data->d_size = strlen(name) + 1; 552627fce14SJosh Poimboeuf data->d_align = 1; 553627fce14SJosh Poimboeuf 554627fce14SJosh Poimboeuf sec->sh.sh_name = shstrtab->len; 555627fce14SJosh Poimboeuf 556627fce14SJosh Poimboeuf shstrtab->len += strlen(name) + 1; 557627fce14SJosh Poimboeuf shstrtab->changed = true; 558627fce14SJosh Poimboeuf 559627fce14SJosh Poimboeuf return sec; 560627fce14SJosh Poimboeuf } 561627fce14SJosh Poimboeuf 562627fce14SJosh Poimboeuf struct section *elf_create_rela_section(struct elf *elf, struct section *base) 563627fce14SJosh Poimboeuf { 564627fce14SJosh Poimboeuf char *relaname; 565627fce14SJosh Poimboeuf struct section *sec; 566627fce14SJosh Poimboeuf 567627fce14SJosh Poimboeuf relaname = malloc(strlen(base->name) + strlen(".rela") + 1); 568627fce14SJosh Poimboeuf if (!relaname) { 569627fce14SJosh Poimboeuf perror("malloc"); 570627fce14SJosh Poimboeuf return NULL; 571627fce14SJosh Poimboeuf } 572627fce14SJosh Poimboeuf strcpy(relaname, ".rela"); 573627fce14SJosh Poimboeuf strcat(relaname, base->name); 574627fce14SJosh Poimboeuf 575627fce14SJosh Poimboeuf sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0); 5760998b7a0SMartin Kepplinger free(relaname); 577627fce14SJosh Poimboeuf if (!sec) 578627fce14SJosh Poimboeuf return NULL; 579627fce14SJosh Poimboeuf 580627fce14SJosh Poimboeuf base->rela = sec; 581627fce14SJosh Poimboeuf sec->base = base; 582627fce14SJosh Poimboeuf 583627fce14SJosh Poimboeuf sec->sh.sh_type = SHT_RELA; 584627fce14SJosh Poimboeuf sec->sh.sh_addralign = 8; 585627fce14SJosh Poimboeuf sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx; 586627fce14SJosh Poimboeuf sec->sh.sh_info = base->idx; 587627fce14SJosh Poimboeuf sec->sh.sh_flags = SHF_INFO_LINK; 588627fce14SJosh Poimboeuf 589627fce14SJosh Poimboeuf return sec; 590627fce14SJosh Poimboeuf } 591627fce14SJosh Poimboeuf 592627fce14SJosh Poimboeuf int elf_rebuild_rela_section(struct section *sec) 593627fce14SJosh Poimboeuf { 594627fce14SJosh Poimboeuf struct rela *rela; 595627fce14SJosh Poimboeuf int nr, idx = 0, size; 596627fce14SJosh Poimboeuf GElf_Rela *relas; 597627fce14SJosh Poimboeuf 598627fce14SJosh Poimboeuf nr = 0; 599627fce14SJosh Poimboeuf list_for_each_entry(rela, &sec->rela_list, list) 600627fce14SJosh Poimboeuf nr++; 601627fce14SJosh Poimboeuf 602627fce14SJosh Poimboeuf size = nr * sizeof(*relas); 603627fce14SJosh Poimboeuf relas = malloc(size); 604627fce14SJosh Poimboeuf if (!relas) { 605627fce14SJosh Poimboeuf perror("malloc"); 606627fce14SJosh Poimboeuf return -1; 607627fce14SJosh Poimboeuf } 608627fce14SJosh Poimboeuf 609627fce14SJosh Poimboeuf sec->data->d_buf = relas; 610627fce14SJosh Poimboeuf sec->data->d_size = size; 611627fce14SJosh Poimboeuf 612627fce14SJosh Poimboeuf sec->sh.sh_size = size; 613627fce14SJosh Poimboeuf 614627fce14SJosh Poimboeuf idx = 0; 615627fce14SJosh Poimboeuf list_for_each_entry(rela, &sec->rela_list, list) { 616627fce14SJosh Poimboeuf relas[idx].r_offset = rela->offset; 617627fce14SJosh Poimboeuf relas[idx].r_addend = rela->addend; 618627fce14SJosh Poimboeuf relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type); 619627fce14SJosh Poimboeuf idx++; 620627fce14SJosh Poimboeuf } 621627fce14SJosh Poimboeuf 622627fce14SJosh Poimboeuf return 0; 623627fce14SJosh Poimboeuf } 624627fce14SJosh Poimboeuf 625627fce14SJosh Poimboeuf int elf_write(struct elf *elf) 626627fce14SJosh Poimboeuf { 627627fce14SJosh Poimboeuf struct section *sec; 628627fce14SJosh Poimboeuf Elf_Scn *s; 629627fce14SJosh Poimboeuf 63097dab2aeSJosh Poimboeuf /* Update section headers for changed sections: */ 631627fce14SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 632627fce14SJosh Poimboeuf if (sec->changed) { 633627fce14SJosh Poimboeuf s = elf_getscn(elf->elf, sec->idx); 634627fce14SJosh Poimboeuf if (!s) { 635627fce14SJosh Poimboeuf WARN_ELF("elf_getscn"); 636627fce14SJosh Poimboeuf return -1; 637627fce14SJosh Poimboeuf } 638627fce14SJosh Poimboeuf if (!gelf_update_shdr(s, &sec->sh)) { 639627fce14SJosh Poimboeuf WARN_ELF("gelf_update_shdr"); 640627fce14SJosh Poimboeuf return -1; 641627fce14SJosh Poimboeuf } 642627fce14SJosh Poimboeuf } 643627fce14SJosh Poimboeuf } 644627fce14SJosh Poimboeuf 64597dab2aeSJosh Poimboeuf /* Make sure the new section header entries get updated properly. */ 64697dab2aeSJosh Poimboeuf elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY); 64797dab2aeSJosh Poimboeuf 64897dab2aeSJosh Poimboeuf /* Write all changes to the file. */ 649627fce14SJosh Poimboeuf if (elf_update(elf->elf, ELF_C_WRITE) < 0) { 650627fce14SJosh Poimboeuf WARN_ELF("elf_update"); 651627fce14SJosh Poimboeuf return -1; 652627fce14SJosh Poimboeuf } 653627fce14SJosh Poimboeuf 654627fce14SJosh Poimboeuf return 0; 655627fce14SJosh Poimboeuf } 656627fce14SJosh Poimboeuf 657442f04c3SJosh Poimboeuf void elf_close(struct elf *elf) 658442f04c3SJosh Poimboeuf { 659442f04c3SJosh Poimboeuf struct section *sec, *tmpsec; 660442f04c3SJosh Poimboeuf struct symbol *sym, *tmpsym; 661442f04c3SJosh Poimboeuf struct rela *rela, *tmprela; 662442f04c3SJosh Poimboeuf 663baa41469SJosh Poimboeuf if (elf->elf) 664baa41469SJosh Poimboeuf elf_end(elf->elf); 665baa41469SJosh Poimboeuf 666baa41469SJosh Poimboeuf if (elf->fd > 0) 667baa41469SJosh Poimboeuf close(elf->fd); 668baa41469SJosh Poimboeuf 669442f04c3SJosh Poimboeuf list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) { 670a196e171SJosh Poimboeuf list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) { 671442f04c3SJosh Poimboeuf list_del(&sym->list); 672042ba73fSJosh Poimboeuf hash_del(&sym->hash); 673442f04c3SJosh Poimboeuf free(sym); 674442f04c3SJosh Poimboeuf } 675a196e171SJosh Poimboeuf list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) { 676442f04c3SJosh Poimboeuf list_del(&rela->list); 677042ba73fSJosh Poimboeuf hash_del(&rela->hash); 678442f04c3SJosh Poimboeuf free(rela); 679442f04c3SJosh Poimboeuf } 680442f04c3SJosh Poimboeuf list_del(&sec->list); 681442f04c3SJosh Poimboeuf free(sec); 682442f04c3SJosh Poimboeuf } 683baa41469SJosh Poimboeuf 684442f04c3SJosh Poimboeuf free(elf); 685442f04c3SJosh Poimboeuf } 686