Il 04/11/2013 14:52, Gleb Natapov ha scritto:
> All decode_register() callers check if instruction has rex prefix
> to properly decode one byte operand. It make sense to move the check
> inside.
>
> Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
I guess you'd like to use Linus's extra week and get it in 3.13?
Paolo
> ---
> arch/x86/kvm/emulate.c | 18 +++++++-----------
> 1 file changed, 7 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 282d28c..0bd372f 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -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;
>
--
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