/* * elf.c - ELF access library * * Adapted from kpatch (https://github.com/dynup/kpatch): * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com> * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see <http://www.gnu.org/licenses/>. */ #include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <errno.h> #include "elf.h"#include "warn.h" #define MAX_NAME_LEN 128 struct section *find_section_by_name(struct elf *elf, const char *name){ struct section *sec; list_for_each_entry(sec, &elf->sections, list) if (!strcmp(sec->name, name)) return sec; return NULL;} static struct section *find_section_by_index(struct elf *elf, unsigned int idx){ struct section *sec; list_for_each_entry(sec, &elf->sections, list) if (sec->idx == idx) return sec; return NULL;} static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx){ struct section *sec; struct symbol *sym; list_for_each_entry(sec, &elf->sections, list) hash_for_each_possible(sec->symbol_hash, sym, hash, idx) if (sym->idx == idx) return sym; return NULL;} struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset){ struct symbol *sym; list_for_each_entry(sym, &sec->symbol_list, list) if (sym->type != STT_SECTION && sym->offset == offset) return sym; return NULL;} struct symbol *find_symbol_by_name(struct elf *elf, const char *name){ struct section *sec; struct symbol *sym; list_for_each_entry(sec, &elf->sections, list) list_for_each_entry(sym, &sec->symbol_list, list) if (!strcmp(sym->name, name)) return sym; return NULL;} struct symbol *find_symbol_containing(struct section *sec, unsigned long offset){ struct symbol *sym; list_for_each_entry(sym, &sec->symbol_list, list) if (sym->type != STT_SECTION && offset >= sym->offset && offset < sym->offset + sym->len) return sym; return NULL;} struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, unsigned int len){ struct rela *rela; unsigned long o; if (!sec->rela) return NULL; for (o = offset; o < offset + len; o++) hash_for_each_possible(sec->rela->rela_hash, rela, hash, o) if (rela->offset == o) return rela; return NULL;} struct rela *find_rela_by_dest(struct section *sec, unsigned long offset){ return find_rela_by_dest_range(sec, offset, 1);} struct symbol *find_containing_func(struct section *sec, unsigned long offset){ struct symbol *func; list_for_each_entry(func, &sec->symbol_list, list) if (func->type == STT_FUNC && offset >= func->offset && offset < func->offset + func->len) return func; return NULL;} static int read_sections(struct elf *elf){ Elf_Scn *s = NULL; struct section *sec; size_t shstrndx, sections_nr; int i; if (elf_getshdrnum(elf->elf, §ions_nr)) { WARN_ELF("elf_getshdrnum"); return -1; } if (elf_getshdrstrndx(elf->elf, &shstrndx)) { WARN_ELF("elf_getshdrstrndx"); return -1; } for (i = 0; i < sections_nr; i++) { sec = malloc(sizeof(*sec)); if (!sec) { perror("malloc"); return -1; } memset(sec, 0, sizeof(*sec)); INIT_LIST_HEAD(&sec->symbol_list); INIT_LIST_HEAD(&sec->rela_list); hash_init(sec->rela_hash); hash_init(sec->symbol_hash); list_add_tail(&sec->list, &elf->sections); s = elf_getscn(elf->elf, i); if (!s) { WARN_ELF("elf_getscn"); return -1; } sec->idx = elf_ndxscn(s); if (!gelf_getshdr(s, &sec->sh)) { WARN_ELF("gelf_getshdr"); return -1; } sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name); if (!sec->name) { WARN_ELF("elf_strptr"); return -1; } if (sec->sh.sh_size != 0) { sec->data = elf_getdata(s, NULL); if (!sec->data) { WARN_ELF("elf_getdata"); return -1; } if (sec->data->d_off != 0 || sec->data->d_size != sec->sh.sh_size) { WARN("unexpected data attributes for %s", sec->name); return -1; } } sec->len = sec->sh.sh_size; } /* sanity check, one more call to elf_nextscn() should return NULL */ if (elf_nextscn(elf->elf, s)) { WARN("section entry mismatch"); return -1; } return 0;} static int read_symbols(struct elf *elf){ struct section *symtab, *sec; struct symbol *sym, *pfunc; struct list_head *entry, *tmp; int symbols_nr, i; char *coldstr; symtab = find_section_by_name(elf, ".symtab"); if (!symtab) { WARN("missing symbol table"); return -1; } symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize; for (i = 0; i < symbols_nr; i++) { sym = malloc(sizeof(*sym)); if (!sym) { perror("malloc"); return -1; } memset(sym, 0, sizeof(*sym)); sym->idx = i; if (!gelf_getsym(symtab->data, i, &sym->sym)) { WARN_ELF("gelf_getsym"); goto err; } sym->name = elf_strptr(elf->elf, symtab->sh.sh_link, sym->sym.st_name); if (!sym->name) { WARN_ELF("elf_strptr"); goto err; } sym->type = GELF_ST_TYPE(sym->sym.st_info); sym->bind = GELF_ST_BIND(sym->sym.st_info); if (sym->sym.st_shndx > SHN_UNDEF && sym->sym.st_shndx < SHN_LORESERVE) { sym->sec = find_section_by_index(elf, sym->sym.st_shndx); if (!sym->sec) { WARN("couldn't find section for symbol %s", sym->name); goto err; } if (sym->type == STT_SECTION) { sym->name = sym->sec->name; sym->sec->sym = sym; } } else sym->sec = find_section_by_index(elf, 0); sym->offset = sym->sym.st_value; sym->len = sym->sym.st_size; /* sorted insert into a per-section list */ entry = &sym->sec->symbol_list; list_for_each_prev(tmp, &sym->sec->symbol_list) { struct symbol *s; s = list_entry(tmp, struct symbol, list); if (sym->offset > s->offset) { entry = tmp; break; } if (sym->offset == s->offset && sym->len >= s->len) { entry = tmp; break; } } list_add(&sym->list, entry); hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx); } /* Create parent/child links for any cold subfunctions */ list_for_each_entry(sec, &elf->sections, list) { list_for_each_entry(sym, &sec->symbol_list, list) { char pname[MAX_NAME_LEN + 1]; size_t pnamelen; if (sym->type != STT_FUNC) continue; sym->pfunc = sym->cfunc = sym; coldstr = strstr(sym->name, ".cold"); if (!coldstr) continue; pnamelen = coldstr - sym->name; if (pnamelen > MAX_NAME_LEN) { WARN("%s(): parent function name exceeds maximum length of %d characters", sym->name, MAX_NAME_LEN); return -1; } strncpy(pname, sym->name, pnamelen); pname[pnamelen] = '\0'; pfunc = find_symbol_by_name(elf, pname); if (!pfunc) { WARN("%s(): can't find parent function", sym->name); return -1; } sym->pfunc = pfunc; pfunc->cfunc = sym; /* * Unfortunately, -fnoreorder-functions puts the child * inside the parent. Remove the overlap so we can * have sane assumptions. * * Note that pfunc->len now no longer matches * pfunc->sym.st_size. */ if (sym->sec == pfunc->sec && sym->offset >= pfunc->offset && sym->offset + sym->len == pfunc->offset + pfunc->len) { pfunc->len -= sym->len; } } } return 0; err: free(sym); return -1;} static int read_relas(struct elf *elf){ struct section *sec; struct rela *rela; int i; unsigned int symndx; list_for_each_entry(sec, &elf->sections, list) { if (sec->sh.sh_type != SHT_RELA) continue; sec->base = find_section_by_name(elf, sec->name + 5); if (!sec->base) { WARN("can't find base section for rela section %s", sec->name); return -1; } sec->base->rela = sec; for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) { rela = malloc(sizeof(*rela)); if (!rela) { perror("malloc"); return -1; } memset(rela, 0, sizeof(*rela)); if (!gelf_getrela(sec->data, i, &rela->rela)) { WARN_ELF("gelf_getrela"); return -1; } rela->type = GELF_R_TYPE(rela->rela.r_info); rela->addend = rela->rela.r_addend; rela->offset = rela->rela.r_offset; symndx = GELF_R_SYM(rela->rela.r_info); rela->sym = find_symbol_by_index(elf, symndx); rela->rela_sec = sec; if (!rela->sym) { WARN("can't find rela entry symbol %d for %s", symndx, sec->name); return -1; } list_add_tail(&rela->list, &sec->rela_list); hash_add(sec->rela_hash, &rela->hash, rela->offset); } } return 0;} struct elf *elf_open(const char *name, int flags){ struct elf *elf; Elf_Cmd cmd; elf_version(EV_CURRENT); elf = malloc(sizeof(*elf)); if (!elf) { perror("malloc"); return NULL; } memset(elf, 0, sizeof(*elf)); INIT_LIST_HEAD(&elf->sections); elf->fd = open(name, flags); if (elf->fd == -1) { fprintf(stderr, "objtool: Can't open '%s': %s\n", name, strerror(errno)); goto err; } if ((flags & O_ACCMODE) == O_RDONLY) cmd = ELF_C_READ_MMAP; else if ((flags & O_ACCMODE) == O_RDWR) cmd = ELF_C_RDWR; else /* O_WRONLY */ cmd = ELF_C_WRITE; elf->elf = elf_begin(elf->fd, cmd, NULL); if (!elf->elf) { WARN_ELF("elf_begin"); goto err; } if (!gelf_getehdr(elf->elf, &elf->ehdr)) { WARN_ELF("gelf_getehdr"); goto err; } if (read_sections(elf)) goto err; if (read_symbols(elf)) goto err; if (read_relas(elf)) goto err; return elf; err: elf_close(elf); return NULL;} struct section *elf_create_section(struct elf *elf, const char *name, size_t entsize, int nr){ struct section *sec, *shstrtab; size_t size = entsize * nr; struct Elf_Scn *s; Elf_Data *data; sec = malloc(sizeof(*sec)); if (!sec) { perror("malloc"); return NULL; } memset(sec, 0, sizeof(*sec)); INIT_LIST_HEAD(&sec->symbol_list); INIT_LIST_HEAD(&sec->rela_list); hash_init(sec->rela_hash); hash_init(sec->symbol_hash); list_add_tail(&sec->list, &elf->sections); s = elf_newscn(elf->elf); if (!s) { WARN_ELF("elf_newscn"); return NULL; } sec->name = strdup(name); if (!sec->name) { perror("strdup"); return NULL; } sec->idx = elf_ndxscn(s);Lines 1–500 of 690. 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/* * elf.c - ELF access library * * Adapted from kpatch (https://github.com/dynup/kpatch): * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com> * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see <http://www.gnu.org/licenses/>. */ #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <errno.h> #include "elf.h" #include "warn.h" #define MAX_NAME_LEN 128 struct section *find_section_by_name(struct elf *elf, const char *name) { struct section *sec; list_for_each_entry(sec, &elf->sections, list) if (!strcmp(sec->name, name)) return sec; return NULL; } static struct section *find_section_by_index(struct elf *elf, unsigned int idx) { struct section *sec; list_for_each_entry(sec, &elf->sections, list) if (sec->idx == idx) return sec; return NULL; } static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx) { struct section *sec; struct symbol *sym; list_for_each_entry(sec, &elf->sections, list) hash_for_each_possible(sec->symbol_hash, sym, hash, idx) if (sym->idx == idx) return sym; return NULL; } struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset) { struct symbol *sym; list_for_each_entry(sym, &sec->symbol_list, list) if (sym->type != STT_SECTION && sym->offset == offset) return sym; return NULL; } struct symbol *find_symbol_by_name(struct elf *elf, const char *name) { struct section *sec; struct symbol *sym; list_for_each_entry(sec, &elf->sections, list) list_for_each_entry(sym, &sec->symbol_list, list) if (!strcmp(sym->name, name)) return sym; return NULL; } struct symbol *find_symbol_containing(struct section *sec, unsigned long offset) { struct symbol *sym; list_for_each_entry(sym, &sec->symbol_list, list) if (sym->type != STT_SECTION && offset >= sym->offset && offset < sym->offset + sym->len) return sym; return NULL; } struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, unsigned int len) { struct rela *rela; unsigned long o; if (!sec->rela) return NULL; for (o = offset; o < offset + len; o++) hash_for_each_possible(sec->rela->rela_hash, rela, hash, o) if (rela->offset == o) return rela; return NULL; } struct rela *find_rela_by_dest(struct section *sec, unsigned long offset) { return find_rela_by_dest_range(sec, offset, 1); } struct symbol *find_containing_func(struct section *sec, unsigned long offset) { struct symbol *func; list_for_each_entry(func, &sec->symbol_list, list) if (func->type == STT_FUNC && offset >= func->offset && offset < func->offset + func->len) return func; return NULL; } static int read_sections(struct elf *elf) { Elf_Scn *s = NULL; struct section *sec; size_t shstrndx, sections_nr; int i; if (elf_getshdrnum(elf->elf, §ions_nr)) { WARN_ELF("elf_getshdrnum"); return -1; } if (elf_getshdrstrndx(elf->elf, &shstrndx)) { WARN_ELF("elf_getshdrstrndx"); return -1; } for (i = 0; i < sections_nr; i++) { sec = malloc(sizeof(*sec)); if (!sec) { perror("malloc"); return -1; } memset(sec, 0, sizeof(*sec)); INIT_LIST_HEAD(&sec->symbol_list); INIT_LIST_HEAD(&sec->rela_list); hash_init(sec->rela_hash); hash_init(sec->symbol_hash); list_add_tail(&sec->list, &elf->sections); s = elf_getscn(elf->elf, i); if (!s) { WARN_ELF("elf_getscn"); return -1; } sec->idx = elf_ndxscn(s); if (!gelf_getshdr(s, &sec->sh)) { WARN_ELF("gelf_getshdr"); return -1; } sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name); if (!sec->name) { WARN_ELF("elf_strptr"); return -1; } if (sec->sh.sh_size != 0) { sec->data = elf_getdata(s, NULL); if (!sec->data) { WARN_ELF("elf_getdata"); return -1; } if (sec->data->d_off != 0 || sec->data->d_size != sec->sh.sh_size) { WARN("unexpected data attributes for %s", sec->name); return -1; } } sec->len = sec->sh.sh_size; } /* sanity check, one more call to elf_nextscn() should return NULL */ if (elf_nextscn(elf->elf, s)) { WARN("section entry mismatch"); return -1; } return 0; } static int read_symbols(struct elf *elf) { struct section *symtab, *sec; struct symbol *sym, *pfunc; struct list_head *entry, *tmp; int symbols_nr, i; char *coldstr; symtab = find_section_by_name(elf, ".symtab"); if (!symtab) { WARN("missing symbol table"); return -1; } symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize; for (i = 0; i < symbols_nr; i++) { sym = malloc(sizeof(*sym)); if (!sym) { perror("malloc"); return -1; } memset(sym, 0, sizeof(*sym)); sym->idx = i; if (!gelf_getsym(symtab->data, i, &sym->sym)) { WARN_ELF("gelf_getsym"); goto err; } sym->name = elf_strptr(elf->elf, symtab->sh.sh_link, sym->sym.st_name); if (!sym->name) { WARN_ELF("elf_strptr"); goto err; } sym->type = GELF_ST_TYPE(sym->sym.st_info); sym->bind = GELF_ST_BIND(sym->sym.st_info); if (sym->sym.st_shndx > SHN_UNDEF && sym->sym.st_shndx < SHN_LORESERVE) { sym->sec = find_section_by_index(elf, sym->sym.st_shndx); if (!sym->sec) { WARN("couldn't find section for symbol %s", sym->name); goto err; } if (sym->type == STT_SECTION) { sym->name = sym->sec->name; sym->sec->sym = sym; } } else sym->sec = find_section_by_index(elf, 0); sym->offset = sym->sym.st_value; sym->len = sym->sym.st_size; /* sorted insert into a per-section list */ entry = &sym->sec->symbol_list; list_for_each_prev(tmp, &sym->sec->symbol_list) { struct symbol *s; s = list_entry(tmp, struct symbol, list); if (sym->offset > s->offset) { entry = tmp; break; } if (sym->offset == s->offset && sym->len >= s->len) { entry = tmp; break; } } list_add(&sym->list, entry); hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx); } /* Create parent/child links for any cold subfunctions */ list_for_each_entry(sec, &elf->sections, list) { list_for_each_entry(sym, &sec->symbol_list, list) { char pname[MAX_NAME_LEN + 1]; size_t pnamelen; if (sym->type != STT_FUNC) continue; sym->pfunc = sym->cfunc = sym; coldstr = strstr(sym->name, ".cold"); if (!coldstr) continue; pnamelen = coldstr - sym->name; if (pnamelen > MAX_NAME_LEN) { WARN("%s(): parent function name exceeds maximum length of %d characters", sym->name, MAX_NAME_LEN); return -1; } strncpy(pname, sym->name, pnamelen); pname[pnamelen] = '\0'; pfunc = find_symbol_by_name(elf, pname); if (!pfunc) { WARN("%s(): can't find parent function", sym->name); return -1; } sym->pfunc = pfunc; pfunc->cfunc = sym; /* * Unfortunately, -fnoreorder-functions puts the child * inside the parent. Remove the overlap so we can * have sane assumptions. * * Note that pfunc->len now no longer matches * pfunc->sym.st_size. */ if (sym->sec == pfunc->sec && sym->offset >= pfunc->offset && sym->offset + sym->len == pfunc->offset + pfunc->len) { pfunc->len -= sym->len; } } } return 0; err: free(sym); return -1; } static int read_relas(struct elf *elf) { struct section *sec; struct rela *rela; int i; unsigned int symndx; list_for_each_entry(sec, &elf->sections, list) { if (sec->sh.sh_type != SHT_RELA) continue; sec->base = find_section_by_name(elf, sec->name + 5); if (!sec->base) { WARN("can't find base section for rela section %s", sec->name); return -1; } sec->base->rela = sec; for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) { rela = malloc(sizeof(*rela)); if (!rela) { perror("malloc"); return -1; } memset(rela, 0, sizeof(*rela)); if (!gelf_getrela(sec->data, i, &rela->rela)) { WARN_ELF("gelf_getrela"); return -1; } rela->type = GELF_R_TYPE(rela->rela.r_info); rela->addend = rela->rela.r_addend; rela->offset = rela->rela.r_offset; symndx = GELF_R_SYM(rela->rela.r_info); rela->sym = find_symbol_by_index(elf, symndx); rela->rela_sec = sec; if (!rela->sym) { WARN("can't find rela entry symbol %d for %s", symndx, sec->name); return -1; } list_add_tail(&rela->list, &sec->rela_list); hash_add(sec->rela_hash, &rela->hash, rela->offset); } } return 0; } struct elf *elf_open(const char *name, int flags) { struct elf *elf; Elf_Cmd cmd; elf_version(EV_CURRENT); elf = malloc(sizeof(*elf)); if (!elf) { perror("malloc"); return NULL; } memset(elf, 0, sizeof(*elf)); INIT_LIST_HEAD(&elf->sections); elf->fd = open(name, flags); if (elf->fd == -1) { fprintf(stderr, "objtool: Can't open '%s': %s\n", name, strerror(errno)); goto err; } if ((flags & O_ACCMODE) == O_RDONLY) cmd = ELF_C_READ_MMAP; else if ((flags & O_ACCMODE) == O_RDWR) cmd = ELF_C_RDWR; else /* O_WRONLY */ cmd = ELF_C_WRITE; elf->elf = elf_begin(elf->fd, cmd, NULL); if (!elf->elf) { WARN_ELF("elf_begin"); goto err; } if (!gelf_getehdr(elf->elf, &elf->ehdr)) { WARN_ELF("gelf_getehdr"); goto err; } if (read_sections(elf)) goto err; if (read_symbols(elf)) goto err; if (read_relas(elf)) goto err; return elf; err: elf_close(elf); return NULL; } struct section *elf_create_section(struct elf *elf, const char *name, size_t entsize, int nr) { struct section *sec, *shstrtab; size_t size = entsize * nr; struct Elf_Scn *s; Elf_Data *data; sec = malloc(sizeof(*sec)); if (!sec) { perror("malloc"); return NULL; } memset(sec, 0, sizeof(*sec)); INIT_LIST_HEAD(&sec->symbol_list); INIT_LIST_HEAD(&sec->rela_list); hash_init(sec->rela_hash); hash_init(sec->symbol_hash); list_add_tail(&sec->list, &elf->sections); s = elf_newscn(elf->elf); if (!s) { WARN_ELF("elf_newscn"); return NULL; } sec->name = strdup(name); if (!sec->name) { perror("strdup"); return NULL; } sec->idx = elf_ndxscn(s);