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authorJosh Poimboeuf <jpoimboe@redhat.com>2017-09-20 16:24:32 -0500
committerIngo Molnar <mingo@kernel.org>2017-09-23 15:06:19 +0200
commit0d0970eef3b03ef08b19da5bc3044410731cf38f (patch)
tree3cbc6c409fce79dddb54b110a557a78dc8720086 /tools/objtool/arch
parent4ba55e65f471d011d3ba2ac2022180ea0877d68e (diff)
objtool: Handle another GCC stack pointer adjustment bug
The kbuild bot reported the following warning with GCC 4.4 and a randconfig: net/socket.o: warning: objtool: compat_sock_ioctl()+0x1083: stack state mismatch: cfa1=7+160 cfa2=-1+0 This is caused by another GCC non-optimization, where it backs up and restores the stack pointer for no apparent reason: 2f91: 48 89 e0 mov %rsp,%rax 2f94: 4c 89 e7 mov %r12,%rdi 2f97: 4c 89 f6 mov %r14,%rsi 2f9a: ba 20 00 00 00 mov $0x20,%edx 2f9f: 48 89 c4 mov %rax,%rsp This issue would have been happily ignored before the following commit: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") But now that objtool is paying attention to such stack pointer writes to/from a register, it needs to understand them properly. In this case that means recognizing that the "mov %rsp, %rax" instruction is potentially a backup of the stack pointer. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dmitriy Vyukov <dvyukov@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") Link: http://lkml.kernel.org/r/8c7aa8e9a36fbbb6655d9d8e7cea58958c912da8.1505942196.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools/objtool/arch')
-rw-r--r--tools/objtool/arch/x86/decode.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 0e8c8ec4fd4e..0f22768c0d4d 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -208,14 +208,14 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
break;
case 0x89:
- if (rex == 0x48 && modrm == 0xe5) {
+ if (rex_w && !rex_r && modrm_mod == 3 && modrm_reg == 4) {
- /* mov %rsp, %rbp */
+ /* mov %rsp, reg */
*type = INSN_STACK;
op->src.type = OP_SRC_REG;
op->src.reg = CFI_SP;
op->dest.type = OP_DEST_REG;
- op->dest.reg = CFI_BP;
+ op->dest.reg = op_to_cfi_reg[modrm_rm][rex_b];
break;
}