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Commit aa9ac1a6 authored by Gleb Natapov's avatar Gleb Natapov
Browse files

KVM: emulator: check rex prefix inside decode_register() 



All decode_register() callers check if instruction has rex prefix
to properly decode one byte operand. It make sense to move the check
inside.

Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 95f328d3

arch/x86/kvm/emulate.c

+7 −11
Original line number Diff line number Diff line
@@ -785,9 +785,10 @@ static int do_insn_fetch(struct x86_emulate_ctxt *ctxt, 
 * @highbyte_regs specifies whether to decode AH,CH,DH,BH.

 */

static void *decode_register(struct x86_emulate_ctxt *ctxt, u8 modrm_reg,

			     int highbyte_regs)

			     int byteop)

{

	void *p;

	int highbyte_regs = (ctxt->rex_prefix == 0) && byteop;



	if (highbyte_regs && modrm_reg >= 4 && modrm_reg < 8)

		p = (unsigned char *)reg_rmw(ctxt, modrm_reg & 3) + 1;
@@ -1024,7 +1025,6 @@ static void decode_register_operand(struct x86_emulate_ctxt *ctxt, 
				    struct operand *op)

{

	unsigned reg = ctxt->modrm_reg;

	int highbyte_regs = ctxt->rex_prefix == 0;



	if (!(ctxt->d & ModRM))

		reg = (ctxt->b & 7) | ((ctxt->rex_prefix & 1) << 3);
@@ -1046,10 +1046,10 @@ static void decode_register_operand(struct x86_emulate_ctxt *ctxt, 


	op->type = OP_REG;

	if (ctxt->d & ByteOp) {

		op->addr.reg = decode_register(ctxt, reg, highbyte_regs);

		op->addr.reg = decode_register(ctxt, reg, true);

		op->bytes = 1;

	} else {

		op->addr.reg = decode_register(ctxt, reg, 0);

		op->addr.reg = decode_register(ctxt, reg, false);

		op->bytes = ctxt->op_bytes;

	}

	fetch_register_operand(op);
@@ -1082,12 +1082,10 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt, 
	ctxt->modrm_seg = VCPU_SREG_DS;



	if (ctxt->modrm_mod == 3) {

		int highbyte_regs = ctxt->rex_prefix == 0;



		op->type = OP_REG;

		op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;

		op->addr.reg = decode_register(ctxt, ctxt->modrm_rm,

					       highbyte_regs && (ctxt->d & ByteOp));

				ctxt->d & ByteOp);

		if (ctxt->d & Sse) {

			op->type = OP_XMM;

			op->bytes = 16;
@@ -4117,10 +4115,8 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op, 
	case OpMem8:

		ctxt->memop.bytes = 1;

		if (ctxt->memop.type == OP_REG) {

			int highbyte_regs = ctxt->rex_prefix == 0;



			ctxt->memop.addr.reg = decode_register(ctxt, ctxt->modrm_rm,

					       highbyte_regs);

			ctxt->memop.addr.reg = decode_register(ctxt,

					ctxt->modrm_rm, true);

			fetch_register_operand(&ctxt->memop);

		}

		goto mem_common;