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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: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
This commit is contained in:
Gleb Natapov 2013-11-04 15:52:41 +02:00
parent 95f328d3ad
commit aa9ac1a632
1 changed files with 7 additions and 11 deletions
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18
arch/x86/kvm/emulate.c
View File

@ -785,9 +785,10 @@ static int do_insn_fetch(struct x86_emulate_ctxt *ctxt,
* @highbyte_regs specifies whether to decode AH,CH,DH,BH. * @highbyte_regs specifies whether to decode AH,CH,DH,BH.
*/ */
static void *decode_register(struct x86_emulate_ctxt *ctxt, u8 modrm_reg, static void *decode_register(struct x86_emulate_ctxt *ctxt, u8 modrm_reg,
int highbyte_regs) int byteop)
{ {
void *p; void *p;
int highbyte_regs = (ctxt->rex_prefix == 0) && byteop;
if (highbyte_regs && modrm_reg >= 4 && modrm_reg < 8) if (highbyte_regs && modrm_reg >= 4 && modrm_reg < 8)
p = (unsigned char *)reg_rmw(ctxt, modrm_reg & 3) + 1; 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) struct operand *op)
{ {
unsigned reg = ctxt->modrm_reg; unsigned reg = ctxt->modrm_reg;
int highbyte_regs = ctxt->rex_prefix == 0;
if (!(ctxt->d & ModRM)) if (!(ctxt->d & ModRM))
reg = (ctxt->b & 7) | ((ctxt->rex_prefix & 1) << 3); 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; op->type = OP_REG;
if (ctxt->d & ByteOp) { if (ctxt->d & ByteOp) {
op->addr.reg = decode_register(ctxt, reg, highbyte_regs); op->addr.reg = decode_register(ctxt, reg, true);
op->bytes = 1; op->bytes = 1;
} else { } else {
op->addr.reg = decode_register(ctxt, reg, 0); op->addr.reg = decode_register(ctxt, reg, false);
op->bytes = ctxt->op_bytes; op->bytes = ctxt->op_bytes;
} }
fetch_register_operand(op); fetch_register_operand(op);
@ -1082,12 +1082,10 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
ctxt->modrm_seg = VCPU_SREG_DS; ctxt->modrm_seg = VCPU_SREG_DS;
if (ctxt->modrm_mod == 3) { if (ctxt->modrm_mod == 3) {
int highbyte_regs = ctxt->rex_prefix == 0;
op->type = OP_REG; op->type = OP_REG;
op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes; op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;
op->addr.reg = decode_register(ctxt, ctxt->modrm_rm, op->addr.reg = decode_register(ctxt, ctxt->modrm_rm,
highbyte_regs && (ctxt->d & ByteOp)); ctxt->d & ByteOp);
if (ctxt->d & Sse) { if (ctxt->d & Sse) {
op->type = OP_XMM; op->type = OP_XMM;
op->bytes = 16; op->bytes = 16;
@ -4117,10 +4115,8 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
case OpMem8: case OpMem8:
ctxt->memop.bytes = 1; ctxt->memop.bytes = 1;
if (ctxt->memop.type == OP_REG) { if (ctxt->memop.type == OP_REG) {
int highbyte_regs = ctxt->rex_prefix == 0; ctxt->memop.addr.reg = decode_register(ctxt,
ctxt->modrm_rm, true);
ctxt->memop.addr.reg = decode_register(ctxt, ctxt->modrm_rm,
highbyte_regs);
fetch_register_operand(&ctxt->memop); fetch_register_operand(&ctxt->memop);
} }
goto mem_common; goto mem_common;