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Two objtool fixes:

Browse Source 
- fix a bug that corrupts the code by mistakenly rewriting
    conditional jumps,
  - and fix another bug generating an incorrect ELF symbol table
    during retpoline rewriting.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-urgent-2021-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fixes from Ingo Molnar:
 "Two objtool fixes:

   - fix a bug that corrupts the code by mistakenly rewriting
     conditional jumps

   - fix another bug generating an incorrect ELF symbol table
     during retpoline rewriting"

* tag 'objtool-urgent-2021-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Only rewrite unconditional retpoline thunk calls
  objtool: Fix .symtab_shndx handling for elf_create_undef_symbol()
This commit is contained in:
Linus Torvalds 2021-06-12 11:10:28 -07:00
commit 768895fb77
2 changed files with 28 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
tools/objtool/arch/x86/decode.c
View File

@ -747,6 +747,10 @@ int arch_rewrite_retpolines(struct objtool_file *file)
list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
if (insn->type != INSN_JUMP_DYNAMIC &&
insn->type != INSN_CALL_DYNAMIC)
continue;
if (!strcmp(insn->sec->name, ".text.__x86.indirect_thunk"))
continue;

25
tools/objtool/elf.c
View File

@ -717,7 +717,7 @@ static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name)
{
struct section *symtab;
struct section *symtab, *symtab_shndx;
struct symbol *sym;
Elf_Data *data;
Elf_Scn *s;
@ -769,6 +769,29 @@ struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name)
symtab->len += data->d_size;
symtab->changed = true;
symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
if (symtab_shndx) {
s = elf_getscn(elf->elf, symtab_shndx->idx);
if (!s) {
WARN_ELF("elf_getscn");
return NULL;
}
data = elf_newdata(s);
if (!data) {
WARN_ELF("elf_newdata");
return NULL;
}
data->d_buf = &sym->sym.st_size; /* conveniently 0 */
data->d_size = sizeof(Elf32_Word);
data->d_align = 4;
data->d_type = ELF_T_WORD;
symtab_shndx->len += 4;
symtab_shndx->changed = true;
}
sym->sec = find_section_by_index(elf, 0);
elf_add_symbol(elf, sym);