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Commit 5b8de48e authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar
Browse files

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



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: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: baa41469 ("objtool: Implement stack validation 2.0")
Link: http://lkml.kernel.org/r/4ea1db896e821226efe1f8e09f270771bde47e65.1501188854.git.jpoimboe@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 0e2bb2bc

tools/objtool/arch/x86/decode.c

+25 −1
Original line number Original line Diff line number Diff line
@@ -271,7 +271,7 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, 
	case 0x8d:

	case 0x8d:

		if (rex == 0x48 && modrm == 0x65) {

		if (rex == 0x48 && modrm == 0x65) {





			/* lea -disp(%rbp), %rsp */

			/* lea disp(%rbp), %rsp */

			*type = INSN_STACK;

			*type = INSN_STACK;

			op->src.type = OP_SRC_ADD;

			op->src.type = OP_SRC_ADD;

			op->src.reg = CFI_BP;

			op->src.reg = CFI_BP;
@@ -281,6 +281,30 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, 
			break;

			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 &&

		if (rex == 0x4c && modrm == 0x54 && sib == 0x24 &&

		    insn.displacement.value == 8) {

		    insn.displacement.value == 8) {