mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-06 22:06:40 +07:00
5c51f4ae84
Arnd Bergmann reported a (false positive) objtool warning:
drivers/infiniband/sw/rxe/rxe_resp.o: warning: objtool: rxe_responder()+0xfe: sibling call from callable instruction with changed frame pointer
The issue is in find_switch_table(). It tries to find a switch
statement's jump table by walking backwards from an indirect jump
instruction, looking for a relocation to the .rodata section. In this
case it stopped walking prematurely: the first .rodata relocation it
encountered was for a variable (resp_state_name) instead of a jump
table, so it just assumed there wasn't a jump table.
The fix is to ignore any .rodata relocation which refers to an ELF
object symbol. This works because the jump tables are anonymous and
have no symbols associated with them.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 3732710ff6
("objtool: Improve rare switch jump table pattern detection")
Link: http://lkml.kernel.org/r/20170302225723.3ndbsnl4hkqbne7a@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
432 lines
8.9 KiB
C
432 lines
8.9 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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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 "elf.h"
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#include "warn.h"
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/*
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* Fallback for systems without this "read, mmaping if possible" cmd.
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*/
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#ifndef ELF_C_READ_MMAP
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#define ELF_C_READ_MMAP ELF_C_READ
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#endif
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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_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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perror("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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perror("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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perror("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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perror("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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perror("elf_strptr");
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return -1;
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}
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sec->elf_data = elf_getdata(s, NULL);
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if (!sec->elf_data) {
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perror("elf_getdata");
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return -1;
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}
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if (sec->elf_data->d_off != 0 ||
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sec->elf_data->d_size != sec->sh.sh_size) {
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WARN("unexpected data attributes for %s", sec->name);
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return -1;
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}
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sec->data = (unsigned long)sec->elf_data->d_buf;
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sec->len = sec->elf_data->d_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;
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struct symbol *sym;
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struct list_head *entry, *tmp;
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int symbols_nr, i;
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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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sym->idx = i;
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if (!gelf_getsym(symtab->elf_data, i, &sym->sym)) {
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perror("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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perror("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 && 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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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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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->elf_data, i, &rela->rela)) {
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perror("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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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)
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{
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struct elf *elf;
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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->name = strdup(name);
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if (!elf->name) {
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perror("strdup");
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goto err;
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}
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elf->fd = open(name, O_RDONLY);
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if (elf->fd == -1) {
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perror("open");
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goto err;
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}
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elf->elf = elf_begin(elf->fd, ELF_C_READ_MMAP, NULL);
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if (!elf->elf) {
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perror("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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perror("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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void elf_close(struct elf *elf)
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{
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struct section *sec, *tmpsec;
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struct symbol *sym, *tmpsym;
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struct rela *rela, *tmprela;
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list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
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list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
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list_del(&sym->list);
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hash_del(&sym->hash);
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free(sym);
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}
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list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) {
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list_del(&rela->list);
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hash_del(&rela->hash);
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free(rela);
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}
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list_del(&sec->list);
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free(sec);
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}
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if (elf->name)
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free(elf->name);
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if (elf->fd > 0)
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close(elf->fd);
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if (elf->elf)
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elf_end(elf->elf);
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free(elf);
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}
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