Re: [Qemu-devel] [PATCH] target-s390x: fix CC computation for EX instruction

[Richard Henderson]

On 05/16/2015 04:28 PM, Aurelien Jarno wrote:
> Commit 7a6c7067f optimized CC computation by only saving cc_op before
> calling helpers as they either don't touch the CC or generate a new
> static value. This however doesn't work for the EX instruction as the
> helper changes or not the CC value depending on the actual executed
> instruction (e.g. MVC vs CLC).
> 
> This patches force a CC computation before calling the helper. This
> fixes random memory corruption occuring in guests.
> 
> Cc: Richard Henderson <address@hidden>
> Cc: Alexander Graf <address@hidden>
> Signed-off-by: Aurelien Jarno <address@hidden>
> ---
>  target-s390x/translate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/target-s390x/translate.c b/target-s390x/translate.c
> index 80e3a54..10522df 100644
> --- a/target-s390x/translate.c
> +++ b/target-s390x/translate.c
> @@ -2095,7 +2095,7 @@ static ExitStatus op_ex(DisasContext *s, DisasOps *o)
>      TCGv_i64 tmp;
>  
>      update_psw_addr(s);
> -    update_cc_op(s);
> +    gen_op_calc_cc(s);
>  
>      tmp = tcg_const_i64(s->next_pc);
>      gen_helper_ex(cc_op, cpu_env, cc_op, o->in1, o->in2, tmp);

I agree this is a bug, and the right fix.

You can also remove the set_cc_static at the end of op_ex, since that's done by
gen_op_calc_cc.


r~