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authorJosh Poimboeuf <jpoimboe@redhat.com>2016-10-10 15:24:01 -0500
committerIngo Molnar <mingo@kernel.org>2016-10-11 10:35:45 +0200
commit2cc17fda94c5ee8c64c2fdc2ef981fc277e2e958 (patch)
tree8511b60eb9f6faa3e023e59b392dca690ae3ed1a
parent597f03f9d133e9837d00965016170271d4f87dcf (diff)
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 <arnd@arndb.de> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--tools/objtool/arch/x86/decode.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index c0c0b265e88e..b63a31be1218 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;