* Re: [patch] (big) real mode emulation - jb
[not found] ` <1193791471.9258.20.camel-mpPvwfgnXtFHIUuj5cj4Omt3HXsI98Cx0E9HWUfgJXw@public.gmane.org>
@ 2007-10-31 0:59 ` Avi Kivity
0 siblings, 0 replies; 2+ messages in thread
From: Avi Kivity @ 2007-10-31 0:59 UTC (permalink / raw)
To: nitin.a.kamble-ral2JQCrhuEAvxtiuMwx3w; +Cc: kvm-devel
Nitin A Kamble wrote:
> Hi Avi,
> Attached is the patch to implement emulation of instruction:
>
> jb (opcode 0xe3)
> [PATCH] Implement emulation of instruction jb (conditional jump)
> opcodes: 0xe3
> From:
> Nitin A Kamble <nitin.a.kamble-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> To:
> Date:
> 2007-10-31 05:41
>
> Signed-off-by: Nitin A Kamble <nitin.a.kamble-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> ---
> drivers/kvm/x86_emulate.c | 25 ++++++++++++++++++++++++-
> 1 files changed, 24 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
> index 579cfcf..1357355 100644
> --- a/drivers/kvm/x86_emulate.c
> +++ b/drivers/kvm/x86_emulate.c
> @@ -165,7 +165,7 @@ static u16 opcode_table[256] = {
> /* 0xD8 - 0xDF */
> 0, 0, 0, 0, 0, 0, 0, 0,
> /* 0xE0 - 0xE7 */
> - 0, 0, 0, 0, 0, 0, 0, 0,
> + 0, 0, 0, ImplicitOps, 0, 0, 0, 0,
> /* 0xE8 - 0xEF */
> ImplicitOps, SrcImm|ImplicitOps, 0, SrcImmByte|ImplicitOps, 0,
> 0, 0, 0,
> /* 0xF0 - 0xF7 */
> @@ -1446,6 +1446,29 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt,
> struct x86_emulate_ops *ops)
> c->src.val = c->regs[VCPU_REGS_RCX];
> emulate_grp2(ctxt);
> break;
> + case 0xe3 : /* jb */ {
> + int rel = insn_fetch(s8, 1, c->eip);
> + int condition = 0;
> + if (test_cc(c->b, ctxt->eflags)) {
> + switch (c->op_bytes) {
> + case 2:
> + condition =
> + (0 == *(u16 *)
> &c->regs[VCPU_REGS_RCX]);
> + break;
> + case 4:
> + condition =
> + (0 == *(u32 *)
> &c->regs[VCPU_REGS_RCX]);
> + break;
> + case 8:
> + condition =
> + (0 == *(u64 *)
> &c->regs[VCPU_REGS_RCX]);
> + break;
> + }
> + }
> + if (condition)
> + JMP_REL(rel);
> + break;
> + }
> case 0xf6 ... 0xf7: /* Grp3 */
> rc = emulate_grp3(ctxt, ops);
> if (rc != 0)
This looks more like jcxz?
--
Any sufficiently difficult bug is indistinguishable from a feature.
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