>From 60c982d4d04014adb3bde1ebee6ca95320ffb213 Mon Sep 17 00:00:00 2001 Message-Id: <60c982d4d04014adb3bde1ebee6ca95320ffb213.1476150736.git.jpoim...@redhat.com> From: Josh Poimboeuf <[email protected]> Date: Mon, 10 Oct 2016 15:24:01 -0500 Subject: [PATCH] objtool: support '-mtune=atom' stack frame setup instruction
Arnd reported that enabling CONFIG_MATOM results in a bunch of objtool false positive frame pointer warnings: arch/x86/events/intel/ds.o: warning: objtool: intel_pmu_pebs_del()+0x43: call without frame pointer save/setup security/keys/keyring.o: warning: objtool: keyring_read()+0x59: call without frame pointer save/setup kernel/signal.o: warning: objtool: __dequeue_signal()+0xd8: call without frame pointer save/setup ... objtool gets confused by the fact that the '-mtune=atom' gcc option sometimes uses 'lea (%rsp),%rbp' instead of 'mov %rsp,%rbp'. The instructions are effectively the same, but objtool doesn't know about the 'lea' variant. Fix the false warnings by adding support for 'lea (%rsp),%rbp' in the objtool decoder. Reported-by: Arnd Bergmann <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> --- tools/objtool/arch/x86/decode.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index c0c0b26..b63a31b 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -98,6 +98,15 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, *type = INSN_FP_SETUP; break; + case 0x8d: + if (insn.rex_prefix.bytes && + insn.rex_prefix.bytes[0] == 0x48 && + insn.modrm.nbytes && insn.modrm.bytes[0] == 0x2c && + insn.sib.nbytes && insn.sib.bytes[0] == 0x24) + /* lea %(rsp), %rbp */ + *type = INSN_FP_SETUP; + break; + case 0x90: *type = INSN_NOP; break; -- 2.7.4
