![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 2 normalized pattern(s): 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 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 [based] [from] [clk] [highbank] [c] you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 355 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com> Reviewed-by: Steve Winslow <swinslow@gmail.com> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
686 lines
14 KiB
C
686 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* elf.c - ELF access library
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*
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* Adapted from kpatch (https://github.com/dynup/kpatch):
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* Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
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* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include "elf.h"
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#include "warn.h"
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#define MAX_NAME_LEN 128
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struct section *find_section_by_name(struct elf *elf, const char *name)
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{
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struct section *sec;
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list_for_each_entry(sec, &elf->sections, list)
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if (!strcmp(sec->name, name))
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return sec;
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return NULL;
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}
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static struct section *find_section_by_index(struct elf *elf,
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unsigned int idx)
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{
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struct section *sec;
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list_for_each_entry(sec, &elf->sections, list)
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if (sec->idx == idx)
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return sec;
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return NULL;
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}
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static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
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{
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struct section *sec;
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struct symbol *sym;
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list_for_each_entry(sec, &elf->sections, list)
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hash_for_each_possible(sec->symbol_hash, sym, hash, idx)
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if (sym->idx == idx)
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return sym;
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return NULL;
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}
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struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
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{
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struct symbol *sym;
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list_for_each_entry(sym, &sec->symbol_list, list)
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if (sym->type != STT_SECTION &&
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sym->offset == offset)
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return sym;
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return NULL;
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}
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struct symbol *find_symbol_by_name(struct elf *elf, const char *name)
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{
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struct section *sec;
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struct symbol *sym;
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list_for_each_entry(sec, &elf->sections, list)
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list_for_each_entry(sym, &sec->symbol_list, list)
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if (!strcmp(sym->name, name))
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return sym;
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return NULL;
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}
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struct symbol *find_symbol_containing(struct section *sec, unsigned long offset)
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{
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struct symbol *sym;
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list_for_each_entry(sym, &sec->symbol_list, list)
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if (sym->type != STT_SECTION &&
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offset >= sym->offset && offset < sym->offset + sym->len)
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return sym;
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return NULL;
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}
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struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset,
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unsigned int len)
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{
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struct rela *rela;
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unsigned long o;
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if (!sec->rela)
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return NULL;
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for (o = offset; o < offset + len; o++)
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hash_for_each_possible(sec->rela->rela_hash, rela, hash, o)
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if (rela->offset == o)
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return rela;
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return NULL;
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}
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struct rela *find_rela_by_dest(struct section *sec, unsigned long offset)
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{
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return find_rela_by_dest_range(sec, offset, 1);
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}
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struct symbol *find_containing_func(struct section *sec, unsigned long offset)
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{
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struct symbol *func;
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list_for_each_entry(func, &sec->symbol_list, list)
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if (func->type == STT_FUNC && offset >= func->offset &&
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offset < func->offset + func->len)
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return func;
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return NULL;
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}
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static int read_sections(struct elf *elf)
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{
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Elf_Scn *s = NULL;
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struct section *sec;
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size_t shstrndx, sections_nr;
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int i;
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if (elf_getshdrnum(elf->elf, §ions_nr)) {
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WARN_ELF("elf_getshdrnum");
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return -1;
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}
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if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
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WARN_ELF("elf_getshdrstrndx");
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return -1;
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}
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for (i = 0; i < sections_nr; i++) {
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sec = malloc(sizeof(*sec));
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if (!sec) {
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perror("malloc");
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return -1;
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}
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memset(sec, 0, sizeof(*sec));
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INIT_LIST_HEAD(&sec->symbol_list);
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INIT_LIST_HEAD(&sec->rela_list);
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hash_init(sec->rela_hash);
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hash_init(sec->symbol_hash);
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list_add_tail(&sec->list, &elf->sections);
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s = elf_getscn(elf->elf, i);
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if (!s) {
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WARN_ELF("elf_getscn");
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return -1;
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}
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sec->idx = elf_ndxscn(s);
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if (!gelf_getshdr(s, &sec->sh)) {
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WARN_ELF("gelf_getshdr");
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return -1;
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}
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sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
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if (!sec->name) {
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WARN_ELF("elf_strptr");
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return -1;
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}
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if (sec->sh.sh_size != 0) {
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sec->data = elf_getdata(s, NULL);
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if (!sec->data) {
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WARN_ELF("elf_getdata");
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return -1;
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}
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if (sec->data->d_off != 0 ||
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sec->data->d_size != sec->sh.sh_size) {
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WARN("unexpected data attributes for %s",
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sec->name);
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return -1;
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}
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}
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sec->len = sec->sh.sh_size;
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}
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/* sanity check, one more call to elf_nextscn() should return NULL */
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if (elf_nextscn(elf->elf, s)) {
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WARN("section entry mismatch");
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return -1;
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}
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return 0;
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}
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static int read_symbols(struct elf *elf)
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{
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struct section *symtab, *sec;
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struct symbol *sym, *pfunc, *alias;
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struct list_head *entry, *tmp;
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int symbols_nr, i;
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char *coldstr;
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symtab = find_section_by_name(elf, ".symtab");
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if (!symtab) {
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WARN("missing symbol table");
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return -1;
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}
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symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
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for (i = 0; i < symbols_nr; i++) {
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sym = malloc(sizeof(*sym));
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if (!sym) {
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perror("malloc");
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return -1;
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}
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memset(sym, 0, sizeof(*sym));
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alias = sym;
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sym->idx = i;
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if (!gelf_getsym(symtab->data, i, &sym->sym)) {
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WARN_ELF("gelf_getsym");
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goto err;
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}
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sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
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sym->sym.st_name);
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if (!sym->name) {
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WARN_ELF("elf_strptr");
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goto err;
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}
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sym->type = GELF_ST_TYPE(sym->sym.st_info);
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sym->bind = GELF_ST_BIND(sym->sym.st_info);
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if (sym->sym.st_shndx > SHN_UNDEF &&
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sym->sym.st_shndx < SHN_LORESERVE) {
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sym->sec = find_section_by_index(elf,
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sym->sym.st_shndx);
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if (!sym->sec) {
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WARN("couldn't find section for symbol %s",
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sym->name);
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goto err;
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}
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if (sym->type == STT_SECTION) {
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sym->name = sym->sec->name;
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sym->sec->sym = sym;
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}
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} else
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sym->sec = find_section_by_index(elf, 0);
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sym->offset = sym->sym.st_value;
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sym->len = sym->sym.st_size;
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/* sorted insert into a per-section list */
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entry = &sym->sec->symbol_list;
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list_for_each_prev(tmp, &sym->sec->symbol_list) {
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struct symbol *s;
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s = list_entry(tmp, struct symbol, list);
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if (sym->offset > s->offset) {
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entry = tmp;
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break;
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}
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if (sym->offset == s->offset) {
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if (sym->len == s->len && alias == sym)
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alias = s;
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if (sym->len >= s->len) {
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entry = tmp;
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break;
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}
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}
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}
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sym->alias = alias;
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list_add(&sym->list, entry);
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hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx);
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}
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/* Create parent/child links for any cold subfunctions */
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list_for_each_entry(sec, &elf->sections, list) {
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list_for_each_entry(sym, &sec->symbol_list, list) {
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char pname[MAX_NAME_LEN + 1];
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size_t pnamelen;
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if (sym->type != STT_FUNC)
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continue;
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sym->pfunc = sym->cfunc = sym;
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coldstr = strstr(sym->name, ".cold");
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if (!coldstr)
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continue;
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pnamelen = coldstr - sym->name;
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if (pnamelen > MAX_NAME_LEN) {
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WARN("%s(): parent function name exceeds maximum length of %d characters",
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sym->name, MAX_NAME_LEN);
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return -1;
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}
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strncpy(pname, sym->name, pnamelen);
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pname[pnamelen] = '\0';
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pfunc = find_symbol_by_name(elf, pname);
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if (!pfunc) {
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WARN("%s(): can't find parent function",
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sym->name);
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return -1;
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}
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sym->pfunc = pfunc;
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pfunc->cfunc = sym;
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/*
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* Unfortunately, -fnoreorder-functions puts the child
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* inside the parent. Remove the overlap so we can
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* have sane assumptions.
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*
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* Note that pfunc->len now no longer matches
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* pfunc->sym.st_size.
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*/
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if (sym->sec == pfunc->sec &&
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sym->offset >= pfunc->offset &&
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sym->offset + sym->len == pfunc->offset + pfunc->len) {
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pfunc->len -= sym->len;
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}
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}
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}
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return 0;
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err:
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free(sym);
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return -1;
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}
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static int read_relas(struct elf *elf)
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{
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struct section *sec;
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struct rela *rela;
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int i;
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unsigned int symndx;
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list_for_each_entry(sec, &elf->sections, list) {
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if (sec->sh.sh_type != SHT_RELA)
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continue;
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sec->base = find_section_by_name(elf, sec->name + 5);
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if (!sec->base) {
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WARN("can't find base section for rela section %s",
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sec->name);
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return -1;
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}
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sec->base->rela = sec;
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for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
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rela = malloc(sizeof(*rela));
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if (!rela) {
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perror("malloc");
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return -1;
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}
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memset(rela, 0, sizeof(*rela));
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if (!gelf_getrela(sec->data, i, &rela->rela)) {
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WARN_ELF("gelf_getrela");
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return -1;
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}
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rela->type = GELF_R_TYPE(rela->rela.r_info);
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rela->addend = rela->rela.r_addend;
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rela->offset = rela->rela.r_offset;
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symndx = GELF_R_SYM(rela->rela.r_info);
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rela->sym = find_symbol_by_index(elf, symndx);
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rela->rela_sec = sec;
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if (!rela->sym) {
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WARN("can't find rela entry symbol %d for %s",
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symndx, sec->name);
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return -1;
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}
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list_add_tail(&rela->list, &sec->rela_list);
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hash_add(sec->rela_hash, &rela->hash, rela->offset);
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}
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}
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return 0;
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}
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struct elf *elf_open(const char *name, int flags)
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{
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struct elf *elf;
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Elf_Cmd cmd;
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elf_version(EV_CURRENT);
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elf = malloc(sizeof(*elf));
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if (!elf) {
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perror("malloc");
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return NULL;
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}
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memset(elf, 0, sizeof(*elf));
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INIT_LIST_HEAD(&elf->sections);
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elf->fd = open(name, flags);
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if (elf->fd == -1) {
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fprintf(stderr, "objtool: Can't open '%s': %s\n",
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name, strerror(errno));
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goto err;
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}
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if ((flags & O_ACCMODE) == O_RDONLY)
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cmd = ELF_C_READ_MMAP;
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else if ((flags & O_ACCMODE) == O_RDWR)
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cmd = ELF_C_RDWR;
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else /* O_WRONLY */
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cmd = ELF_C_WRITE;
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elf->elf = elf_begin(elf->fd, cmd, NULL);
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if (!elf->elf) {
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WARN_ELF("elf_begin");
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goto err;
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}
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if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
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WARN_ELF("gelf_getehdr");
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goto err;
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}
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if (read_sections(elf))
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goto err;
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if (read_symbols(elf))
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goto err;
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if (read_relas(elf))
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goto err;
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return elf;
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err:
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elf_close(elf);
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return NULL;
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}
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struct section *elf_create_section(struct elf *elf, const char *name,
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size_t entsize, int nr)
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{
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struct section *sec, *shstrtab;
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size_t size = entsize * nr;
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struct Elf_Scn *s;
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Elf_Data *data;
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sec = malloc(sizeof(*sec));
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if (!sec) {
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perror("malloc");
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return NULL;
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}
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memset(sec, 0, sizeof(*sec));
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INIT_LIST_HEAD(&sec->symbol_list);
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INIT_LIST_HEAD(&sec->rela_list);
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hash_init(sec->rela_hash);
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hash_init(sec->symbol_hash);
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list_add_tail(&sec->list, &elf->sections);
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s = elf_newscn(elf->elf);
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if (!s) {
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WARN_ELF("elf_newscn");
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return NULL;
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}
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sec->name = strdup(name);
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if (!sec->name) {
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perror("strdup");
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return NULL;
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}
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sec->idx = elf_ndxscn(s);
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sec->len = size;
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sec->changed = true;
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sec->data = elf_newdata(s);
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if (!sec->data) {
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WARN_ELF("elf_newdata");
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return NULL;
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}
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sec->data->d_size = size;
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sec->data->d_align = 1;
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if (size) {
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sec->data->d_buf = malloc(size);
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if (!sec->data->d_buf) {
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perror("malloc");
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return NULL;
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}
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memset(sec->data->d_buf, 0, size);
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}
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if (!gelf_getshdr(s, &sec->sh)) {
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WARN_ELF("gelf_getshdr");
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return NULL;
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}
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sec->sh.sh_size = size;
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sec->sh.sh_entsize = entsize;
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sec->sh.sh_type = SHT_PROGBITS;
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sec->sh.sh_addralign = 1;
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sec->sh.sh_flags = SHF_ALLOC;
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/* Add section name to .shstrtab (or .strtab for Clang) */
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shstrtab = find_section_by_name(elf, ".shstrtab");
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if (!shstrtab)
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shstrtab = find_section_by_name(elf, ".strtab");
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if (!shstrtab) {
|
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WARN("can't find .shstrtab or .strtab section");
|
|
return NULL;
|
|
}
|
|
|
|
s = elf_getscn(elf->elf, shstrtab->idx);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return NULL;
|
|
}
|
|
|
|
data = elf_newdata(s);
|
|
if (!data) {
|
|
WARN_ELF("elf_newdata");
|
|
return NULL;
|
|
}
|
|
|
|
data->d_buf = sec->name;
|
|
data->d_size = strlen(name) + 1;
|
|
data->d_align = 1;
|
|
|
|
sec->sh.sh_name = shstrtab->len;
|
|
|
|
shstrtab->len += strlen(name) + 1;
|
|
shstrtab->changed = true;
|
|
|
|
return sec;
|
|
}
|
|
|
|
struct section *elf_create_rela_section(struct elf *elf, struct section *base)
|
|
{
|
|
char *relaname;
|
|
struct section *sec;
|
|
|
|
relaname = malloc(strlen(base->name) + strlen(".rela") + 1);
|
|
if (!relaname) {
|
|
perror("malloc");
|
|
return NULL;
|
|
}
|
|
strcpy(relaname, ".rela");
|
|
strcat(relaname, base->name);
|
|
|
|
sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0);
|
|
free(relaname);
|
|
if (!sec)
|
|
return NULL;
|
|
|
|
base->rela = sec;
|
|
sec->base = base;
|
|
|
|
sec->sh.sh_type = SHT_RELA;
|
|
sec->sh.sh_addralign = 8;
|
|
sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
|
|
sec->sh.sh_info = base->idx;
|
|
sec->sh.sh_flags = SHF_INFO_LINK;
|
|
|
|
return sec;
|
|
}
|
|
|
|
int elf_rebuild_rela_section(struct section *sec)
|
|
{
|
|
struct rela *rela;
|
|
int nr, idx = 0, size;
|
|
GElf_Rela *relas;
|
|
|
|
nr = 0;
|
|
list_for_each_entry(rela, &sec->rela_list, list)
|
|
nr++;
|
|
|
|
size = nr * sizeof(*relas);
|
|
relas = malloc(size);
|
|
if (!relas) {
|
|
perror("malloc");
|
|
return -1;
|
|
}
|
|
|
|
sec->data->d_buf = relas;
|
|
sec->data->d_size = size;
|
|
|
|
sec->sh.sh_size = size;
|
|
|
|
idx = 0;
|
|
list_for_each_entry(rela, &sec->rela_list, list) {
|
|
relas[idx].r_offset = rela->offset;
|
|
relas[idx].r_addend = rela->addend;
|
|
relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type);
|
|
idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int elf_write(struct elf *elf)
|
|
{
|
|
struct section *sec;
|
|
Elf_Scn *s;
|
|
|
|
/* Update section headers for changed sections: */
|
|
list_for_each_entry(sec, &elf->sections, list) {
|
|
if (sec->changed) {
|
|
s = elf_getscn(elf->elf, sec->idx);
|
|
if (!s) {
|
|
WARN_ELF("elf_getscn");
|
|
return -1;
|
|
}
|
|
if (!gelf_update_shdr(s, &sec->sh)) {
|
|
WARN_ELF("gelf_update_shdr");
|
|
return -1;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Make sure the new section header entries get updated properly. */
|
|
elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
|
|
|
|
/* Write all changes to the file. */
|
|
if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
|
|
WARN_ELF("elf_update");
|
|
return -1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void elf_close(struct elf *elf)
|
|
{
|
|
struct section *sec, *tmpsec;
|
|
struct symbol *sym, *tmpsym;
|
|
struct rela *rela, *tmprela;
|
|
|
|
if (elf->elf)
|
|
elf_end(elf->elf);
|
|
|
|
if (elf->fd > 0)
|
|
close(elf->fd);
|
|
|
|
list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
|
|
list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
|
|
list_del(&sym->list);
|
|
hash_del(&sym->hash);
|
|
free(sym);
|
|
}
|
|
list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) {
|
|
list_del(&rela->list);
|
|
hash_del(&rela->hash);
|
|
free(rela);
|
|
}
|
|
list_del(&sec->list);
|
|
free(sec);
|
|
}
|
|
|
|
free(elf);
|
|
}
|