Commit 961d83b9 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

objtool,x86: Rewrite ADD/SUB/AND 



Support sign extending and imm8 forms.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Tested-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173627.588366777@infradead.org
parent 78df6245

tools/objtool/arch/x86/decode.c

+51 −19
Original line number Diff line number Diff line
@@ -98,13 +98,14 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, 
			    struct list_head *ops_list)

{

	struct insn insn;

	int x86_64, sign;

	int x86_64;

	unsigned char op1, op2,

		      rex = 0, rex_b = 0, rex_r = 0, rex_w = 0, rex_x = 0,

		      modrm = 0, modrm_mod = 0, modrm_rm = 0, modrm_reg = 0,

		      sib = 0, /* sib_scale = 0, */ sib_index = 0, sib_base = 0;

	struct stack_op *op = NULL;

	struct symbol *sym;

	u64 imm;



	x86_64 = is_x86_64(elf);

	if (x86_64 == -1)
@@ -200,40 +201,71 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec, 
		*type = INSN_JUMP_CONDITIONAL;

		break;



	case 0x81:

	case 0x83:

		if (rex != 0x48)

	case 0x80 ... 0x83:

		/*

		 * 1000 00sw : mod OP r/m : immediate

		 *

		 * s - sign extend immediate

		 * w - imm8 / imm32

		 *

		 * OP: 000 ADD    100 AND

		 *     001 OR     101 SUB

		 *     010 ADC    110 XOR

		 *     011 SBB    111 CMP

		 */



		/* 64bit only */

		if (!rex_w)

			break;



		if (modrm == 0xe4) {

			/* and imm, %rsp */

		/* %rsp target only */

		if (!(modrm_mod == 3 && modrm_rm == CFI_SP))

			break;



		imm = insn.immediate.value;

		if (op1 & 2) { /* sign extend */

			if (op1 & 1) { /* imm32 */

				imm <<= 32;

				imm = (s64)imm >> 32;

			} else { /* imm8 */

				imm <<= 56;

				imm = (s64)imm >> 56;

			}

		}



		switch (modrm_reg & 7) {

		case 5:

			imm = -imm;

			/* fallthrough */

		case 0:

			/* add/sub imm, %rsp */

			ADD_OP(op) {

				op->src.type = OP_SRC_AND;

				op->src.type = OP_SRC_ADD;

				op->src.reg = CFI_SP;

				op->src.offset = insn.immediate.value;

				op->src.offset = imm;

				op->dest.type = OP_DEST_REG;

				op->dest.reg = CFI_SP;

			}

			break;

		}



		if (modrm == 0xc4)

			sign = 1;

		else if (modrm == 0xec)

			sign = -1;

		else

			break;



		/* add/sub imm, %rsp */

		case 4:

			/* and imm, %rsp */

			ADD_OP(op) {

			op->src.type = OP_SRC_ADD;

				op->src.type = OP_SRC_AND;

				op->src.reg = CFI_SP;

			op->src.offset = insn.immediate.value * sign;

				op->src.offset = insn.immediate.value;

				op->dest.type = OP_DEST_REG;

				op->dest.reg = CFI_SP;

			}

			break;



		default:

			/* WARN ? */

			break;

		}



		break;



	case 0x89:

		if (!rex_w)

			break;