Re: [PATCH] target/s390x/translate: Fix RNSBG instruction

[David Hildenbrand]

On 30.01.20 14:34, Thomas Huth wrote:
> RNSBG is handled via the op_rosbg() helper function. But RNSBG has
> the opcode 0xEC54, i.e. 0x54 as second byte, while op_rosbg() currently
> checks for 0x55. This seems to be a typo, fix it to use 0x54 instead,
> so that op_rosbg() does not abort() anymore if a program uses RNSBG.
> 
> I've checked with a simply test function that I now get the same results
> with KVM and with TCG:
> 
>  static void test_rnsbg(void)
>  {
>       uint64_t r1, r2;
> 
>       r2 = 0xffff000000000000UL;
>       r1 = 0x123456789bdfaaaaUL;
>       asm volatile (" rnsbg %0,%1,12,61,16 " : "+r"(r1) : "r"(r2));
> 
>       printf("r1 afterwards: 0x%lx\n", r1);
>  }

You could add a tcg test case for that :)

> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1860920
> Signed-off-by: Thomas Huth <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 0bd2073718..4f6f1e31cd 100644
> --- a/target/s390x/translate.c
> +++ b/target/s390x/translate.c
> @@ -3874,7 +3874,7 @@ static DisasJumpType op_rosbg(DisasContext *s, DisasOps 
> *o)
>  
>      /* Operate.  */
>      switch (s->fields.op2) {
> -    case 0x55: /* AND */
> +    case 0x54: /* AND */
>          tcg_gen_ori_i64(o->in2, o->in2, ~mask);
>          tcg_gen_and_i64(o->out, o->out, o->in2);
>          break;
> 

Fixes: d6c6372e186e ("target-s390: Implement R[NOX]SBG")

Reviewed-by: David Hildenbrand <address@hidden>

Thanks!

-- 
Thanks,

David / dhildenb