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objtool: Fix '-mtune=atom' decoding support in objtool 2.0

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With '-mtune=atom', which is enabled with CONFIG_MATOM=y, GCC uses some
unusual instructions for setting up the stack.

Instead of:

  mov %rsp, %rbp

it does:

  lea (%rsp), %rbp

And instead of:

  add imm, %rsp

it does:

  lea disp(%rsp), %rsp

Add support for these instructions to the objtool decoder.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: baa41469a7 ("objtool: Implement stack validation 2.0")
Link: http://lkml.kernel.org/r/4ea1db896e821226efe1f8e09f270771bde47e65.1501188854.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2017-07-27 15:56:55 -05:00 committed by Ingo Molnar
parent 0e2bb2bc14
commit 5b8de48e82
1 changed files with 25 additions and 1 deletions
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26
tools/objtool/arch/x86/decode.c
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@ -271,7 +271,7 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
case 0x8d:
if (rex == 0x48 && modrm == 0x65) {
/* lea -disp(%rbp), %rsp */
/* lea disp(%rbp), %rsp */
*type = INSN_STACK;
op->src.type = OP_SRC_ADD;
op->src.reg = CFI_BP;
@ -281,6 +281,30 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
break;
}
if (rex == 0x48 && (modrm == 0xa4 || modrm == 0x64) &&
sib == 0x24) {
/* lea disp(%rsp), %rsp */
*type = INSN_STACK;
op->src.type = OP_SRC_ADD;
op->src.reg = CFI_SP;
op->src.offset = insn.displacement.value;
op->dest.type = OP_DEST_REG;
op->dest.reg = CFI_SP;
break;
}
if (rex == 0x48 && modrm == 0x2c && sib == 0x24) {
/* lea (%rsp), %rbp */
*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;
break;
}
if (rex == 0x4c && modrm == 0x54 && sib == 0x24 &&
insn.displacement.value == 8) {