Re: [PATCH 1/2] KVM: x86 emulator: Add decoding of 16bit second in memory argument

[Avi Kivity <avi@redhat.com>]

On 02/24/2010 12:28 PM, Gleb Natapov wrote:
> Add decoding of Ep type of argument used by callf/jmpf.
>
> Signed-off-by: Gleb Natapov<gleb@redhat.com>
> ---
>   arch/x86/kvm/emulate.c |   16 ++++++++++++++++
>   1 files changed, 16 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index c9f604b..d288107 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -85,6 +85,7 @@
>   #define Src2ImmByte (2<<29)
>   #define Src2One     (3<<29)
>   #define Src2Imm16   (4<<29)
> +#define Src2Mem16   (5<<29)
>   #define Src2Mask    (7<<29)
>
>   enum {
> @@ -1163,6 +1164,10 @@ done_prefixes:
>   		c->src2.bytes = 1;
>   		c->src2.val = 1;
>   		break;
> +	case Src2Mem16:
> +		c->src2.bytes = 2;
> +		c->src2.type = OP_MEM;
> +		break;
>   	}
>
>   	/* Decode and fetch the destination operand: register or memory. */
> @@ -1881,6 +1886,17 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
>   		c->src.orig_val = c->src.val;
>   	}
>
> +	if (c->src2.type == OP_MEM) {
> +		c->src2.ptr = (unsigned long *)(memop + c->src.bytes);
> +		c->src2.val = 0;
> +		rc = ops->read_emulated((unsigned long)c->src2.ptr,
> +					&c->src2.val,
> +					c->src2.bytes,
> +					ctxt->vcpu);
> +		if (rc != X86EMUL_CONTINUE)
> +			goto done;
> +	}
> +
>    

This introduces a dependency between src and src2.  The alternative is 
to have an offset+segment operand type, but that introduces all types of 
complications, so I guess the dependency is worth it.  But at least 
document it when you define Src2Mem16.

-- 
error compiling committee.c: too many arguments to function