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Date: Thu, 1 Jul 2010 23:52:48 +0200
From: Aurelien Jarno <aurelien@aurel32.net>
Subject: Re: [Qemu-devel] [PATCH] target-i386: Fix xchg rax,r8
Message-ID: <20100701215248.GD25251@ohm.aurel32.net>
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To: Richard Henderson <rth@twiddle.net>
Cc: qemu-devel@nongnu.org, 600589@bugs.launchpad.net

On Thu, Jul 01, 2010 at 09:42:21AM -0700, Richard Henderson wrote:
> We were ignoring REX_B while special-casing NOP, i.e. xchg eax,eax.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  target-i386/translate.c |    9 +++++++--
>  1 files changed, 7 insertions(+), 2 deletions(-)

Applied, thanks.

> diff --git a/target-i386/translate.c b/target-i386/translate.c
> index 708b0a1..8cb5cf0 100644
> --- a/target-i386/translate.c
> +++ b/target-i386/translate.c
> @@ -5293,6 +5293,7 @@ static target_ulong disas_insn(DisasContext *s, target_ulong pc_start)
>          break;
>  
>      case 0x91 ... 0x97: /* xchg R, EAX */
> +    do_xchg_reg_eax:
>          ot = dflag + OT_WORD;
>          reg = (b & 7) | REX_B(s);
>          rm = R_EAX;
> @@ -6663,10 +6664,14 @@ static target_ulong disas_insn(DisasContext *s, target_ulong pc_start)
>          /************************/
>          /* misc */
>      case 0x90: /* nop */
> -        /* XXX: xchg + rex handling */
>          /* XXX: correct lock test for all insn */
> -        if (prefixes & PREFIX_LOCK)
> +        if (prefixes & PREFIX_LOCK) {
>              goto illegal_op;
> +        }
> +        /* If REX_B is set, then this is xchg eax, r8d, not a nop.  */
> +        if (REX_B(s)) {
> +            goto do_xchg_reg_eax;
> +        }
>          if (prefixes & PREFIX_REPZ) {
>              gen_svm_check_intercept(s, pc_start, SVM_EXIT_PAUSE);
>          }
> -- 
> 1.7.0.1
> 
> 
> 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net