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 symbol *sym; 50442f04c3SJosh Poimboeuf 5165fb11a7SPeter Zijlstra hash_for_each_possible(elf->symbol_hash, sym, hash, idx) 52442f04c3SJosh Poimboeuf if (sym->idx == idx) 53442f04c3SJosh Poimboeuf return sym; 54442f04c3SJosh Poimboeuf 55442f04c3SJosh Poimboeuf return NULL; 56442f04c3SJosh Poimboeuf } 57442f04c3SJosh Poimboeuf 58442f04c3SJosh Poimboeuf struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset) 59442f04c3SJosh Poimboeuf { 60442f04c3SJosh Poimboeuf struct symbol *sym; 61442f04c3SJosh Poimboeuf 62a196e171SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 637acfe531SJosh Poimboeuf if (sym->type != STT_SECTION && sym->offset == offset) 647acfe531SJosh Poimboeuf return sym; 657acfe531SJosh Poimboeuf 667acfe531SJosh Poimboeuf return NULL; 677acfe531SJosh Poimboeuf } 687acfe531SJosh Poimboeuf 697acfe531SJosh Poimboeuf struct symbol *find_func_by_offset(struct section *sec, unsigned long offset) 707acfe531SJosh Poimboeuf { 717acfe531SJosh Poimboeuf struct symbol *sym; 727acfe531SJosh Poimboeuf 737acfe531SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 747acfe531SJosh Poimboeuf if (sym->type == STT_FUNC && sym->offset == offset) 75442f04c3SJosh Poimboeuf return sym; 76442f04c3SJosh Poimboeuf 77442f04c3SJosh Poimboeuf return NULL; 78442f04c3SJosh Poimboeuf } 79442f04c3SJosh Poimboeuf 8013810435SJosh Poimboeuf struct symbol *find_symbol_by_name(struct elf *elf, const char *name) 8113810435SJosh Poimboeuf { 8213810435SJosh Poimboeuf struct section *sec; 8313810435SJosh Poimboeuf struct symbol *sym; 8413810435SJosh Poimboeuf 8513810435SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) 8613810435SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 8713810435SJosh Poimboeuf if (!strcmp(sym->name, name)) 8813810435SJosh Poimboeuf return sym; 8913810435SJosh Poimboeuf 9013810435SJosh Poimboeuf return NULL; 9113810435SJosh Poimboeuf } 9213810435SJosh Poimboeuf 935c51f4aeSJosh Poimboeuf struct symbol *find_symbol_containing(struct section *sec, unsigned long offset) 945c51f4aeSJosh Poimboeuf { 955c51f4aeSJosh Poimboeuf struct symbol *sym; 965c51f4aeSJosh Poimboeuf 975c51f4aeSJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) 985c51f4aeSJosh Poimboeuf if (sym->type != STT_SECTION && 995c51f4aeSJosh Poimboeuf offset >= sym->offset && offset < sym->offset + sym->len) 1005c51f4aeSJosh Poimboeuf return sym; 1015c51f4aeSJosh Poimboeuf 1025c51f4aeSJosh Poimboeuf return NULL; 1035c51f4aeSJosh Poimboeuf } 1045c51f4aeSJosh Poimboeuf 105442f04c3SJosh Poimboeuf struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, 106442f04c3SJosh Poimboeuf unsigned int len) 107442f04c3SJosh Poimboeuf { 108442f04c3SJosh Poimboeuf struct rela *rela; 109042ba73fSJosh Poimboeuf unsigned long o; 110442f04c3SJosh Poimboeuf 111442f04c3SJosh Poimboeuf if (!sec->rela) 112442f04c3SJosh Poimboeuf return NULL; 113442f04c3SJosh Poimboeuf 114042ba73fSJosh Poimboeuf for (o = offset; o < offset + len; o++) 115042ba73fSJosh Poimboeuf hash_for_each_possible(sec->rela->rela_hash, rela, hash, o) 116042ba73fSJosh Poimboeuf if (rela->offset == o) 117442f04c3SJosh Poimboeuf return rela; 118442f04c3SJosh Poimboeuf 119442f04c3SJosh Poimboeuf return NULL; 120442f04c3SJosh Poimboeuf } 121442f04c3SJosh Poimboeuf 122442f04c3SJosh Poimboeuf struct rela *find_rela_by_dest(struct section *sec, unsigned long offset) 123442f04c3SJosh Poimboeuf { 124442f04c3SJosh Poimboeuf return find_rela_by_dest_range(sec, offset, 1); 125442f04c3SJosh Poimboeuf } 126442f04c3SJosh Poimboeuf 127442f04c3SJosh Poimboeuf struct symbol *find_containing_func(struct section *sec, unsigned long offset) 128442f04c3SJosh Poimboeuf { 129442f04c3SJosh Poimboeuf struct symbol *func; 130442f04c3SJosh Poimboeuf 131a196e171SJosh Poimboeuf list_for_each_entry(func, &sec->symbol_list, list) 132442f04c3SJosh Poimboeuf if (func->type == STT_FUNC && offset >= func->offset && 133442f04c3SJosh Poimboeuf offset < func->offset + func->len) 134442f04c3SJosh Poimboeuf return func; 135442f04c3SJosh Poimboeuf 136442f04c3SJosh Poimboeuf return NULL; 137442f04c3SJosh Poimboeuf } 138442f04c3SJosh Poimboeuf 139442f04c3SJosh Poimboeuf static int read_sections(struct elf *elf) 140442f04c3SJosh Poimboeuf { 141442f04c3SJosh Poimboeuf Elf_Scn *s = NULL; 142442f04c3SJosh Poimboeuf struct section *sec; 143442f04c3SJosh Poimboeuf size_t shstrndx, sections_nr; 144442f04c3SJosh Poimboeuf int i; 145442f04c3SJosh Poimboeuf 146442f04c3SJosh Poimboeuf if (elf_getshdrnum(elf->elf, §ions_nr)) { 147baa41469SJosh Poimboeuf WARN_ELF("elf_getshdrnum"); 148442f04c3SJosh Poimboeuf return -1; 149442f04c3SJosh Poimboeuf } 150442f04c3SJosh Poimboeuf 151442f04c3SJosh Poimboeuf if (elf_getshdrstrndx(elf->elf, &shstrndx)) { 152baa41469SJosh Poimboeuf WARN_ELF("elf_getshdrstrndx"); 153442f04c3SJosh Poimboeuf return -1; 154442f04c3SJosh Poimboeuf } 155442f04c3SJosh Poimboeuf 156442f04c3SJosh Poimboeuf for (i = 0; i < sections_nr; i++) { 157442f04c3SJosh Poimboeuf sec = malloc(sizeof(*sec)); 158442f04c3SJosh Poimboeuf if (!sec) { 159442f04c3SJosh Poimboeuf perror("malloc"); 160442f04c3SJosh Poimboeuf return -1; 161442f04c3SJosh Poimboeuf } 162442f04c3SJosh Poimboeuf memset(sec, 0, sizeof(*sec)); 163442f04c3SJosh Poimboeuf 164a196e171SJosh Poimboeuf INIT_LIST_HEAD(&sec->symbol_list); 165a196e171SJosh Poimboeuf INIT_LIST_HEAD(&sec->rela_list); 166042ba73fSJosh Poimboeuf hash_init(sec->rela_hash); 167442f04c3SJosh Poimboeuf 168442f04c3SJosh Poimboeuf list_add_tail(&sec->list, &elf->sections); 169442f04c3SJosh Poimboeuf 170442f04c3SJosh Poimboeuf s = elf_getscn(elf->elf, i); 171442f04c3SJosh Poimboeuf if (!s) { 172baa41469SJosh Poimboeuf WARN_ELF("elf_getscn"); 173442f04c3SJosh Poimboeuf return -1; 174442f04c3SJosh Poimboeuf } 175442f04c3SJosh Poimboeuf 176442f04c3SJosh Poimboeuf sec->idx = elf_ndxscn(s); 177442f04c3SJosh Poimboeuf 178442f04c3SJosh Poimboeuf if (!gelf_getshdr(s, &sec->sh)) { 179baa41469SJosh Poimboeuf WARN_ELF("gelf_getshdr"); 180442f04c3SJosh Poimboeuf return -1; 181442f04c3SJosh Poimboeuf } 182442f04c3SJosh Poimboeuf 183442f04c3SJosh Poimboeuf sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name); 184442f04c3SJosh Poimboeuf if (!sec->name) { 185baa41469SJosh Poimboeuf WARN_ELF("elf_strptr"); 186442f04c3SJosh Poimboeuf return -1; 187442f04c3SJosh Poimboeuf } 188442f04c3SJosh Poimboeuf 189df968c93SPetr Vandrovec if (sec->sh.sh_size != 0) { 190baa41469SJosh Poimboeuf sec->data = elf_getdata(s, NULL); 191baa41469SJosh Poimboeuf if (!sec->data) { 192baa41469SJosh Poimboeuf WARN_ELF("elf_getdata"); 193442f04c3SJosh Poimboeuf return -1; 194442f04c3SJosh Poimboeuf } 195baa41469SJosh Poimboeuf if (sec->data->d_off != 0 || 196baa41469SJosh Poimboeuf sec->data->d_size != sec->sh.sh_size) { 197df968c93SPetr Vandrovec WARN("unexpected data attributes for %s", 198df968c93SPetr Vandrovec sec->name); 199442f04c3SJosh Poimboeuf return -1; 200442f04c3SJosh Poimboeuf } 201df968c93SPetr Vandrovec } 202df968c93SPetr Vandrovec sec->len = sec->sh.sh_size; 203442f04c3SJosh Poimboeuf } 204442f04c3SJosh Poimboeuf 205442f04c3SJosh Poimboeuf /* sanity check, one more call to elf_nextscn() should return NULL */ 206442f04c3SJosh Poimboeuf if (elf_nextscn(elf->elf, s)) { 207442f04c3SJosh Poimboeuf WARN("section entry mismatch"); 208442f04c3SJosh Poimboeuf return -1; 209442f04c3SJosh Poimboeuf } 210442f04c3SJosh Poimboeuf 211442f04c3SJosh Poimboeuf return 0; 212442f04c3SJosh Poimboeuf } 213442f04c3SJosh Poimboeuf 214442f04c3SJosh Poimboeuf static int read_symbols(struct elf *elf) 215442f04c3SJosh Poimboeuf { 21613810435SJosh Poimboeuf struct section *symtab, *sec; 21709f30d83SPeter Zijlstra struct symbol *sym, *pfunc, *alias; 218442f04c3SJosh Poimboeuf struct list_head *entry, *tmp; 219442f04c3SJosh Poimboeuf int symbols_nr, i; 22013810435SJosh Poimboeuf char *coldstr; 221442f04c3SJosh Poimboeuf 222442f04c3SJosh Poimboeuf symtab = find_section_by_name(elf, ".symtab"); 223442f04c3SJosh Poimboeuf if (!symtab) { 224442f04c3SJosh Poimboeuf WARN("missing symbol table"); 225442f04c3SJosh Poimboeuf return -1; 226442f04c3SJosh Poimboeuf } 227442f04c3SJosh Poimboeuf 228442f04c3SJosh Poimboeuf symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize; 229442f04c3SJosh Poimboeuf 230442f04c3SJosh Poimboeuf for (i = 0; i < symbols_nr; i++) { 231442f04c3SJosh Poimboeuf sym = malloc(sizeof(*sym)); 232442f04c3SJosh Poimboeuf if (!sym) { 233442f04c3SJosh Poimboeuf perror("malloc"); 234442f04c3SJosh Poimboeuf return -1; 235442f04c3SJosh Poimboeuf } 236442f04c3SJosh Poimboeuf memset(sym, 0, sizeof(*sym)); 23709f30d83SPeter Zijlstra alias = sym; 238442f04c3SJosh Poimboeuf 239442f04c3SJosh Poimboeuf sym->idx = i; 240442f04c3SJosh Poimboeuf 241baa41469SJosh Poimboeuf if (!gelf_getsym(symtab->data, i, &sym->sym)) { 242baa41469SJosh Poimboeuf WARN_ELF("gelf_getsym"); 243442f04c3SJosh Poimboeuf goto err; 244442f04c3SJosh Poimboeuf } 245442f04c3SJosh Poimboeuf 246442f04c3SJosh Poimboeuf sym->name = elf_strptr(elf->elf, symtab->sh.sh_link, 247442f04c3SJosh Poimboeuf sym->sym.st_name); 248442f04c3SJosh Poimboeuf if (!sym->name) { 249baa41469SJosh Poimboeuf WARN_ELF("elf_strptr"); 250442f04c3SJosh Poimboeuf goto err; 251442f04c3SJosh Poimboeuf } 252442f04c3SJosh Poimboeuf 253442f04c3SJosh Poimboeuf sym->type = GELF_ST_TYPE(sym->sym.st_info); 254442f04c3SJosh Poimboeuf sym->bind = GELF_ST_BIND(sym->sym.st_info); 255442f04c3SJosh Poimboeuf 256442f04c3SJosh Poimboeuf if (sym->sym.st_shndx > SHN_UNDEF && 257442f04c3SJosh Poimboeuf sym->sym.st_shndx < SHN_LORESERVE) { 258442f04c3SJosh Poimboeuf sym->sec = find_section_by_index(elf, 259442f04c3SJosh Poimboeuf sym->sym.st_shndx); 260442f04c3SJosh Poimboeuf if (!sym->sec) { 261442f04c3SJosh Poimboeuf WARN("couldn't find section for symbol %s", 262442f04c3SJosh Poimboeuf sym->name); 263442f04c3SJosh Poimboeuf goto err; 264442f04c3SJosh Poimboeuf } 265442f04c3SJosh Poimboeuf if (sym->type == STT_SECTION) { 266442f04c3SJosh Poimboeuf sym->name = sym->sec->name; 267442f04c3SJosh Poimboeuf sym->sec->sym = sym; 268442f04c3SJosh Poimboeuf } 269442f04c3SJosh Poimboeuf } else 270442f04c3SJosh Poimboeuf sym->sec = find_section_by_index(elf, 0); 271442f04c3SJosh Poimboeuf 272442f04c3SJosh Poimboeuf sym->offset = sym->sym.st_value; 273442f04c3SJosh Poimboeuf sym->len = sym->sym.st_size; 274442f04c3SJosh Poimboeuf 275442f04c3SJosh Poimboeuf /* sorted insert into a per-section list */ 276a196e171SJosh Poimboeuf entry = &sym->sec->symbol_list; 277a196e171SJosh Poimboeuf list_for_each_prev(tmp, &sym->sec->symbol_list) { 278442f04c3SJosh Poimboeuf struct symbol *s; 279442f04c3SJosh Poimboeuf 280442f04c3SJosh Poimboeuf s = list_entry(tmp, struct symbol, list); 281442f04c3SJosh Poimboeuf 282442f04c3SJosh Poimboeuf if (sym->offset > s->offset) { 283442f04c3SJosh Poimboeuf entry = tmp; 284442f04c3SJosh Poimboeuf break; 285442f04c3SJosh Poimboeuf } 286442f04c3SJosh Poimboeuf 28709f30d83SPeter Zijlstra if (sym->offset == s->offset) { 288e10cd8feSJosh Poimboeuf if (sym->len && sym->len == s->len && alias == sym) 28909f30d83SPeter Zijlstra alias = s; 29009f30d83SPeter Zijlstra 29109f30d83SPeter Zijlstra if (sym->len >= s->len) { 292442f04c3SJosh Poimboeuf entry = tmp; 293442f04c3SJosh Poimboeuf break; 294442f04c3SJosh Poimboeuf } 295442f04c3SJosh Poimboeuf } 29609f30d83SPeter Zijlstra } 29709f30d83SPeter Zijlstra sym->alias = alias; 298442f04c3SJosh Poimboeuf list_add(&sym->list, entry); 29965fb11a7SPeter Zijlstra hash_add(elf->symbol_hash, &sym->hash, sym->idx); 300442f04c3SJosh Poimboeuf } 301442f04c3SJosh Poimboeuf 30213810435SJosh Poimboeuf /* Create parent/child links for any cold subfunctions */ 30313810435SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 30413810435SJosh Poimboeuf list_for_each_entry(sym, &sec->symbol_list, list) { 30522566c16SArtem Savkov char pname[MAX_NAME_LEN + 1]; 30622566c16SArtem Savkov size_t pnamelen; 30713810435SJosh Poimboeuf if (sym->type != STT_FUNC) 30813810435SJosh Poimboeuf continue; 30913810435SJosh Poimboeuf sym->pfunc = sym->cfunc = sym; 310bcb6fb5dSJosh Poimboeuf coldstr = strstr(sym->name, ".cold"); 31108b393d0SJosh Poimboeuf if (!coldstr) 31208b393d0SJosh Poimboeuf continue; 31308b393d0SJosh Poimboeuf 31422566c16SArtem Savkov pnamelen = coldstr - sym->name; 31522566c16SArtem Savkov if (pnamelen > MAX_NAME_LEN) { 31622566c16SArtem Savkov WARN("%s(): parent function name exceeds maximum length of %d characters", 31722566c16SArtem Savkov sym->name, MAX_NAME_LEN); 31822566c16SArtem Savkov return -1; 31922566c16SArtem Savkov } 32022566c16SArtem Savkov 32122566c16SArtem Savkov strncpy(pname, sym->name, pnamelen); 32222566c16SArtem Savkov pname[pnamelen] = '\0'; 32322566c16SArtem Savkov pfunc = find_symbol_by_name(elf, pname); 32413810435SJosh Poimboeuf 32513810435SJosh Poimboeuf if (!pfunc) { 32613810435SJosh Poimboeuf WARN("%s(): can't find parent function", 32713810435SJosh Poimboeuf sym->name); 3280b9301fbSArtem Savkov return -1; 32913810435SJosh Poimboeuf } 33013810435SJosh Poimboeuf 33113810435SJosh Poimboeuf sym->pfunc = pfunc; 33213810435SJosh Poimboeuf pfunc->cfunc = sym; 33308b393d0SJosh Poimboeuf 33408b393d0SJosh Poimboeuf /* 33508b393d0SJosh Poimboeuf * Unfortunately, -fnoreorder-functions puts the child 33608b393d0SJosh Poimboeuf * inside the parent. Remove the overlap so we can 33708b393d0SJosh Poimboeuf * have sane assumptions. 33808b393d0SJosh Poimboeuf * 33908b393d0SJosh Poimboeuf * Note that pfunc->len now no longer matches 34008b393d0SJosh Poimboeuf * pfunc->sym.st_size. 34108b393d0SJosh Poimboeuf */ 34208b393d0SJosh Poimboeuf if (sym->sec == pfunc->sec && 34308b393d0SJosh Poimboeuf sym->offset >= pfunc->offset && 34408b393d0SJosh Poimboeuf sym->offset + sym->len == pfunc->offset + pfunc->len) { 34508b393d0SJosh Poimboeuf pfunc->len -= sym->len; 34613810435SJosh Poimboeuf } 34713810435SJosh Poimboeuf } 34813810435SJosh Poimboeuf } 34913810435SJosh Poimboeuf 350442f04c3SJosh Poimboeuf return 0; 351442f04c3SJosh Poimboeuf 352442f04c3SJosh Poimboeuf err: 353442f04c3SJosh Poimboeuf free(sym); 354442f04c3SJosh Poimboeuf return -1; 355442f04c3SJosh Poimboeuf } 356442f04c3SJosh Poimboeuf 357442f04c3SJosh Poimboeuf static int read_relas(struct elf *elf) 358442f04c3SJosh Poimboeuf { 359442f04c3SJosh Poimboeuf struct section *sec; 360442f04c3SJosh Poimboeuf struct rela *rela; 361442f04c3SJosh Poimboeuf int i; 362442f04c3SJosh Poimboeuf unsigned int symndx; 363442f04c3SJosh Poimboeuf 364442f04c3SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 365442f04c3SJosh Poimboeuf if (sec->sh.sh_type != SHT_RELA) 366442f04c3SJosh Poimboeuf continue; 367442f04c3SJosh Poimboeuf 368442f04c3SJosh Poimboeuf sec->base = find_section_by_name(elf, sec->name + 5); 369442f04c3SJosh Poimboeuf if (!sec->base) { 370442f04c3SJosh Poimboeuf WARN("can't find base section for rela section %s", 371442f04c3SJosh Poimboeuf sec->name); 372442f04c3SJosh Poimboeuf return -1; 373442f04c3SJosh Poimboeuf } 374442f04c3SJosh Poimboeuf 375442f04c3SJosh Poimboeuf sec->base->rela = sec; 376442f04c3SJosh Poimboeuf 377442f04c3SJosh Poimboeuf for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) { 378442f04c3SJosh Poimboeuf rela = malloc(sizeof(*rela)); 379442f04c3SJosh Poimboeuf if (!rela) { 380442f04c3SJosh Poimboeuf perror("malloc"); 381442f04c3SJosh Poimboeuf return -1; 382442f04c3SJosh Poimboeuf } 383442f04c3SJosh Poimboeuf memset(rela, 0, sizeof(*rela)); 384442f04c3SJosh Poimboeuf 385baa41469SJosh Poimboeuf if (!gelf_getrela(sec->data, i, &rela->rela)) { 386baa41469SJosh Poimboeuf WARN_ELF("gelf_getrela"); 387442f04c3SJosh Poimboeuf return -1; 388442f04c3SJosh Poimboeuf } 389442f04c3SJosh Poimboeuf 390442f04c3SJosh Poimboeuf rela->type = GELF_R_TYPE(rela->rela.r_info); 391442f04c3SJosh Poimboeuf rela->addend = rela->rela.r_addend; 392442f04c3SJosh Poimboeuf rela->offset = rela->rela.r_offset; 393442f04c3SJosh Poimboeuf symndx = GELF_R_SYM(rela->rela.r_info); 394442f04c3SJosh Poimboeuf rela->sym = find_symbol_by_index(elf, symndx); 395e7c2bc37SJosh Poimboeuf rela->sec = sec; 396442f04c3SJosh Poimboeuf if (!rela->sym) { 397442f04c3SJosh Poimboeuf WARN("can't find rela entry symbol %d for %s", 398442f04c3SJosh Poimboeuf symndx, sec->name); 399442f04c3SJosh Poimboeuf return -1; 400442f04c3SJosh Poimboeuf } 401042ba73fSJosh Poimboeuf 402042ba73fSJosh Poimboeuf list_add_tail(&rela->list, &sec->rela_list); 403042ba73fSJosh Poimboeuf hash_add(sec->rela_hash, &rela->hash, rela->offset); 404042ba73fSJosh Poimboeuf 405442f04c3SJosh Poimboeuf } 406442f04c3SJosh Poimboeuf } 407442f04c3SJosh Poimboeuf 408442f04c3SJosh Poimboeuf return 0; 409442f04c3SJosh Poimboeuf } 410442f04c3SJosh Poimboeuf 4118e144797SMichael Forney struct elf *elf_read(const char *name, int flags) 412442f04c3SJosh Poimboeuf { 413442f04c3SJosh Poimboeuf struct elf *elf; 414627fce14SJosh Poimboeuf Elf_Cmd cmd; 415442f04c3SJosh Poimboeuf 416442f04c3SJosh Poimboeuf elf_version(EV_CURRENT); 417442f04c3SJosh Poimboeuf 418442f04c3SJosh Poimboeuf elf = malloc(sizeof(*elf)); 419442f04c3SJosh Poimboeuf if (!elf) { 420442f04c3SJosh Poimboeuf perror("malloc"); 421442f04c3SJosh Poimboeuf return NULL; 422442f04c3SJosh Poimboeuf } 423442f04c3SJosh Poimboeuf memset(elf, 0, sizeof(*elf)); 424442f04c3SJosh Poimboeuf 42565fb11a7SPeter Zijlstra hash_init(elf->symbol_hash); 426442f04c3SJosh Poimboeuf INIT_LIST_HEAD(&elf->sections); 427442f04c3SJosh Poimboeuf 428627fce14SJosh Poimboeuf elf->fd = open(name, flags); 429442f04c3SJosh Poimboeuf if (elf->fd == -1) { 430385d11b1SJosh Poimboeuf fprintf(stderr, "objtool: Can't open '%s': %s\n", 431385d11b1SJosh Poimboeuf name, strerror(errno)); 432442f04c3SJosh Poimboeuf goto err; 433442f04c3SJosh Poimboeuf } 434442f04c3SJosh Poimboeuf 435627fce14SJosh Poimboeuf if ((flags & O_ACCMODE) == O_RDONLY) 436627fce14SJosh Poimboeuf cmd = ELF_C_READ_MMAP; 437627fce14SJosh Poimboeuf else if ((flags & O_ACCMODE) == O_RDWR) 438627fce14SJosh Poimboeuf cmd = ELF_C_RDWR; 439627fce14SJosh Poimboeuf else /* O_WRONLY */ 440627fce14SJosh Poimboeuf cmd = ELF_C_WRITE; 441627fce14SJosh Poimboeuf 442627fce14SJosh Poimboeuf elf->elf = elf_begin(elf->fd, cmd, NULL); 443442f04c3SJosh Poimboeuf if (!elf->elf) { 444baa41469SJosh Poimboeuf WARN_ELF("elf_begin"); 445442f04c3SJosh Poimboeuf goto err; 446442f04c3SJosh Poimboeuf } 447442f04c3SJosh Poimboeuf 448442f04c3SJosh Poimboeuf if (!gelf_getehdr(elf->elf, &elf->ehdr)) { 449baa41469SJosh Poimboeuf WARN_ELF("gelf_getehdr"); 450442f04c3SJosh Poimboeuf goto err; 451442f04c3SJosh Poimboeuf } 452442f04c3SJosh Poimboeuf 453442f04c3SJosh Poimboeuf if (read_sections(elf)) 454442f04c3SJosh Poimboeuf goto err; 455442f04c3SJosh Poimboeuf 456442f04c3SJosh Poimboeuf if (read_symbols(elf)) 457442f04c3SJosh Poimboeuf goto err; 458442f04c3SJosh Poimboeuf 459442f04c3SJosh Poimboeuf if (read_relas(elf)) 460442f04c3SJosh Poimboeuf goto err; 461442f04c3SJosh Poimboeuf 462442f04c3SJosh Poimboeuf return elf; 463442f04c3SJosh Poimboeuf 464442f04c3SJosh Poimboeuf err: 465442f04c3SJosh Poimboeuf elf_close(elf); 466442f04c3SJosh Poimboeuf return NULL; 467442f04c3SJosh Poimboeuf } 468442f04c3SJosh Poimboeuf 469627fce14SJosh Poimboeuf struct section *elf_create_section(struct elf *elf, const char *name, 470627fce14SJosh Poimboeuf size_t entsize, int nr) 471627fce14SJosh Poimboeuf { 472627fce14SJosh Poimboeuf struct section *sec, *shstrtab; 473627fce14SJosh Poimboeuf size_t size = entsize * nr; 4743c3ea503SMichael Forney Elf_Scn *s; 475627fce14SJosh Poimboeuf Elf_Data *data; 476627fce14SJosh Poimboeuf 477627fce14SJosh Poimboeuf sec = malloc(sizeof(*sec)); 478627fce14SJosh Poimboeuf if (!sec) { 479627fce14SJosh Poimboeuf perror("malloc"); 480627fce14SJosh Poimboeuf return NULL; 481627fce14SJosh Poimboeuf } 482627fce14SJosh Poimboeuf memset(sec, 0, sizeof(*sec)); 483627fce14SJosh Poimboeuf 484627fce14SJosh Poimboeuf INIT_LIST_HEAD(&sec->symbol_list); 485627fce14SJosh Poimboeuf INIT_LIST_HEAD(&sec->rela_list); 486627fce14SJosh Poimboeuf hash_init(sec->rela_hash); 487627fce14SJosh Poimboeuf 488627fce14SJosh Poimboeuf list_add_tail(&sec->list, &elf->sections); 489627fce14SJosh Poimboeuf 490627fce14SJosh Poimboeuf s = elf_newscn(elf->elf); 491627fce14SJosh Poimboeuf if (!s) { 492627fce14SJosh Poimboeuf WARN_ELF("elf_newscn"); 493627fce14SJosh Poimboeuf return NULL; 494627fce14SJosh Poimboeuf } 495627fce14SJosh Poimboeuf 496627fce14SJosh Poimboeuf sec->name = strdup(name); 497627fce14SJosh Poimboeuf if (!sec->name) { 498627fce14SJosh Poimboeuf perror("strdup"); 499627fce14SJosh Poimboeuf return NULL; 500627fce14SJosh Poimboeuf } 501627fce14SJosh Poimboeuf 502627fce14SJosh Poimboeuf sec->idx = elf_ndxscn(s); 503627fce14SJosh Poimboeuf sec->len = size; 504627fce14SJosh Poimboeuf sec->changed = true; 505627fce14SJosh Poimboeuf 506627fce14SJosh Poimboeuf sec->data = elf_newdata(s); 507627fce14SJosh Poimboeuf if (!sec->data) { 508627fce14SJosh Poimboeuf WARN_ELF("elf_newdata"); 509627fce14SJosh Poimboeuf return NULL; 510627fce14SJosh Poimboeuf } 511627fce14SJosh Poimboeuf 512627fce14SJosh Poimboeuf sec->data->d_size = size; 513627fce14SJosh Poimboeuf sec->data->d_align = 1; 514627fce14SJosh Poimboeuf 515627fce14SJosh Poimboeuf if (size) { 516627fce14SJosh Poimboeuf sec->data->d_buf = malloc(size); 517627fce14SJosh Poimboeuf if (!sec->data->d_buf) { 518627fce14SJosh Poimboeuf perror("malloc"); 519627fce14SJosh Poimboeuf return NULL; 520627fce14SJosh Poimboeuf } 521627fce14SJosh Poimboeuf memset(sec->data->d_buf, 0, size); 522627fce14SJosh Poimboeuf } 523627fce14SJosh Poimboeuf 524627fce14SJosh Poimboeuf if (!gelf_getshdr(s, &sec->sh)) { 525627fce14SJosh Poimboeuf WARN_ELF("gelf_getshdr"); 526627fce14SJosh Poimboeuf return NULL; 527627fce14SJosh Poimboeuf } 528627fce14SJosh Poimboeuf 529627fce14SJosh Poimboeuf sec->sh.sh_size = size; 530627fce14SJosh Poimboeuf sec->sh.sh_entsize = entsize; 531627fce14SJosh Poimboeuf sec->sh.sh_type = SHT_PROGBITS; 532627fce14SJosh Poimboeuf sec->sh.sh_addralign = 1; 533627fce14SJosh Poimboeuf sec->sh.sh_flags = SHF_ALLOC; 534627fce14SJosh Poimboeuf 535627fce14SJosh Poimboeuf 5366d77d3b4SSimon Ser /* Add section name to .shstrtab (or .strtab for Clang) */ 537627fce14SJosh Poimboeuf shstrtab = find_section_by_name(elf, ".shstrtab"); 5386d77d3b4SSimon Ser if (!shstrtab) 5396d77d3b4SSimon Ser shstrtab = find_section_by_name(elf, ".strtab"); 540627fce14SJosh Poimboeuf if (!shstrtab) { 5416d77d3b4SSimon Ser WARN("can't find .shstrtab or .strtab section"); 542627fce14SJosh Poimboeuf return NULL; 543627fce14SJosh Poimboeuf } 544627fce14SJosh Poimboeuf 545627fce14SJosh Poimboeuf s = elf_getscn(elf->elf, shstrtab->idx); 546627fce14SJosh Poimboeuf if (!s) { 547627fce14SJosh Poimboeuf WARN_ELF("elf_getscn"); 548627fce14SJosh Poimboeuf return NULL; 549627fce14SJosh Poimboeuf } 550627fce14SJosh Poimboeuf 551627fce14SJosh Poimboeuf data = elf_newdata(s); 552627fce14SJosh Poimboeuf if (!data) { 553627fce14SJosh Poimboeuf WARN_ELF("elf_newdata"); 554627fce14SJosh Poimboeuf return NULL; 555627fce14SJosh Poimboeuf } 556627fce14SJosh Poimboeuf 557627fce14SJosh Poimboeuf data->d_buf = sec->name; 558627fce14SJosh Poimboeuf data->d_size = strlen(name) + 1; 559627fce14SJosh Poimboeuf data->d_align = 1; 560627fce14SJosh Poimboeuf 561627fce14SJosh Poimboeuf sec->sh.sh_name = shstrtab->len; 562627fce14SJosh Poimboeuf 563627fce14SJosh Poimboeuf shstrtab->len += strlen(name) + 1; 564627fce14SJosh Poimboeuf shstrtab->changed = true; 565627fce14SJosh Poimboeuf 566627fce14SJosh Poimboeuf return sec; 567627fce14SJosh Poimboeuf } 568627fce14SJosh Poimboeuf 569627fce14SJosh Poimboeuf struct section *elf_create_rela_section(struct elf *elf, struct section *base) 570627fce14SJosh Poimboeuf { 571627fce14SJosh Poimboeuf char *relaname; 572627fce14SJosh Poimboeuf struct section *sec; 573627fce14SJosh Poimboeuf 574627fce14SJosh Poimboeuf relaname = malloc(strlen(base->name) + strlen(".rela") + 1); 575627fce14SJosh Poimboeuf if (!relaname) { 576627fce14SJosh Poimboeuf perror("malloc"); 577627fce14SJosh Poimboeuf return NULL; 578627fce14SJosh Poimboeuf } 579627fce14SJosh Poimboeuf strcpy(relaname, ".rela"); 580627fce14SJosh Poimboeuf strcat(relaname, base->name); 581627fce14SJosh Poimboeuf 582627fce14SJosh Poimboeuf sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0); 5830998b7a0SMartin Kepplinger free(relaname); 584627fce14SJosh Poimboeuf if (!sec) 585627fce14SJosh Poimboeuf return NULL; 586627fce14SJosh Poimboeuf 587627fce14SJosh Poimboeuf base->rela = sec; 588627fce14SJosh Poimboeuf sec->base = base; 589627fce14SJosh Poimboeuf 590627fce14SJosh Poimboeuf sec->sh.sh_type = SHT_RELA; 591627fce14SJosh Poimboeuf sec->sh.sh_addralign = 8; 592627fce14SJosh Poimboeuf sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx; 593627fce14SJosh Poimboeuf sec->sh.sh_info = base->idx; 594627fce14SJosh Poimboeuf sec->sh.sh_flags = SHF_INFO_LINK; 595627fce14SJosh Poimboeuf 596627fce14SJosh Poimboeuf return sec; 597627fce14SJosh Poimboeuf } 598627fce14SJosh Poimboeuf 599627fce14SJosh Poimboeuf int elf_rebuild_rela_section(struct section *sec) 600627fce14SJosh Poimboeuf { 601627fce14SJosh Poimboeuf struct rela *rela; 602627fce14SJosh Poimboeuf int nr, idx = 0, size; 603627fce14SJosh Poimboeuf GElf_Rela *relas; 604627fce14SJosh Poimboeuf 605627fce14SJosh Poimboeuf nr = 0; 606627fce14SJosh Poimboeuf list_for_each_entry(rela, &sec->rela_list, list) 607627fce14SJosh Poimboeuf nr++; 608627fce14SJosh Poimboeuf 609627fce14SJosh Poimboeuf size = nr * sizeof(*relas); 610627fce14SJosh Poimboeuf relas = malloc(size); 611627fce14SJosh Poimboeuf if (!relas) { 612627fce14SJosh Poimboeuf perror("malloc"); 613627fce14SJosh Poimboeuf return -1; 614627fce14SJosh Poimboeuf } 615627fce14SJosh Poimboeuf 616627fce14SJosh Poimboeuf sec->data->d_buf = relas; 617627fce14SJosh Poimboeuf sec->data->d_size = size; 618627fce14SJosh Poimboeuf 619627fce14SJosh Poimboeuf sec->sh.sh_size = size; 620627fce14SJosh Poimboeuf 621627fce14SJosh Poimboeuf idx = 0; 622627fce14SJosh Poimboeuf list_for_each_entry(rela, &sec->rela_list, list) { 623627fce14SJosh Poimboeuf relas[idx].r_offset = rela->offset; 624627fce14SJosh Poimboeuf relas[idx].r_addend = rela->addend; 625627fce14SJosh Poimboeuf relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type); 626627fce14SJosh Poimboeuf idx++; 627627fce14SJosh Poimboeuf } 628627fce14SJosh Poimboeuf 629627fce14SJosh Poimboeuf return 0; 630627fce14SJosh Poimboeuf } 631627fce14SJosh Poimboeuf 632627fce14SJosh Poimboeuf int elf_write(struct elf *elf) 633627fce14SJosh Poimboeuf { 634627fce14SJosh Poimboeuf struct section *sec; 635627fce14SJosh Poimboeuf Elf_Scn *s; 636627fce14SJosh Poimboeuf 63797dab2aeSJosh Poimboeuf /* Update section headers for changed sections: */ 638627fce14SJosh Poimboeuf list_for_each_entry(sec, &elf->sections, list) { 639627fce14SJosh Poimboeuf if (sec->changed) { 640627fce14SJosh Poimboeuf s = elf_getscn(elf->elf, sec->idx); 641627fce14SJosh Poimboeuf if (!s) { 642627fce14SJosh Poimboeuf WARN_ELF("elf_getscn"); 643627fce14SJosh Poimboeuf return -1; 644627fce14SJosh Poimboeuf } 645627fce14SJosh Poimboeuf if (!gelf_update_shdr(s, &sec->sh)) { 646627fce14SJosh Poimboeuf WARN_ELF("gelf_update_shdr"); 647627fce14SJosh Poimboeuf return -1; 648627fce14SJosh Poimboeuf } 649627fce14SJosh Poimboeuf } 650627fce14SJosh Poimboeuf } 651627fce14SJosh Poimboeuf 65297dab2aeSJosh Poimboeuf /* Make sure the new section header entries get updated properly. */ 65397dab2aeSJosh Poimboeuf elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY); 65497dab2aeSJosh Poimboeuf 65597dab2aeSJosh Poimboeuf /* Write all changes to the file. */ 656627fce14SJosh Poimboeuf if (elf_update(elf->elf, ELF_C_WRITE) < 0) { 657627fce14SJosh Poimboeuf WARN_ELF("elf_update"); 658627fce14SJosh Poimboeuf return -1; 659627fce14SJosh Poimboeuf } 660627fce14SJosh Poimboeuf 661627fce14SJosh Poimboeuf return 0; 662627fce14SJosh Poimboeuf } 663627fce14SJosh Poimboeuf 664442f04c3SJosh Poimboeuf void elf_close(struct elf *elf) 665442f04c3SJosh Poimboeuf { 666442f04c3SJosh Poimboeuf struct section *sec, *tmpsec; 667442f04c3SJosh Poimboeuf struct symbol *sym, *tmpsym; 668442f04c3SJosh Poimboeuf struct rela *rela, *tmprela; 669442f04c3SJosh Poimboeuf 670baa41469SJosh Poimboeuf if (elf->elf) 671baa41469SJosh Poimboeuf elf_end(elf->elf); 672baa41469SJosh Poimboeuf 673baa41469SJosh Poimboeuf if (elf->fd > 0) 674baa41469SJosh Poimboeuf close(elf->fd); 675baa41469SJosh Poimboeuf 676442f04c3SJosh Poimboeuf list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) { 677a196e171SJosh Poimboeuf list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) { 678442f04c3SJosh Poimboeuf list_del(&sym->list); 679042ba73fSJosh Poimboeuf hash_del(&sym->hash); 680442f04c3SJosh Poimboeuf free(sym); 681442f04c3SJosh Poimboeuf } 682a196e171SJosh Poimboeuf list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) { 683442f04c3SJosh Poimboeuf list_del(&rela->list); 684042ba73fSJosh Poimboeuf hash_del(&rela->hash); 685442f04c3SJosh Poimboeuf free(rela); 686442f04c3SJosh Poimboeuf } 687442f04c3SJosh Poimboeuf list_del(&sec->list); 688442f04c3SJosh Poimboeuf free(sec); 689442f04c3SJosh Poimboeuf } 690baa41469SJosh Poimboeuf 691442f04c3SJosh Poimboeuf free(elf); 692442f04c3SJosh Poimboeuf } 693