Re: [Qemu-devel] Incorrect handling of PPC64 rldcl insn

[Alexander Graf]

On 05/06/2013 07:00 PM, Torbjorn Granlund wrote:
> I could finally make Debian GNU/Linux install and run under
> qemu-system-ppc64.  I used Debian 7.0.0 and qemu from the main git repo,
> updated a few days ago.
>
> While Debian runs well and not too slowly, GMP fails badly under all
> ABIs, and in many different ways.  I have isolated the first problem.
>
> Test case:
>
> #include<stdio.h>
> int
> main ()
> {
>    unsigned long r;
>    asm ("rldcl\t%0, %1, %2, 0" : "=r" (r) : "r" (0xcafebabedeadbeeful), "r" 
> (16));
>    printf ("%lx\n", r);
>    return 0;
> }
>
> Expected output:
> babedeadbeefcafe
>
> Output under qemu:
> 0
>
> I have single stepped in gdb to determine that it is indeed rldcl that
> misbehaves.

Thanks a lot for the bug report and test case! Please CC qemu-ppc 
whenever you find issues or have patches for PPC. That makes filtering 
for important mails a lot easier.

Does the patch below fix the issue for you?


Alex

diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 0886f4d..a018616 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -1733,8 +1733,6 @@ static inline void gen_rldnm(DisasContext *ctx, 
uint32_t mb, uint32_t me)
 {
     TCGv t0;

-    mb = MB(ctx->opcode);
-    me = ME(ctx->opcode);
     t0 = tcg_temp_new();
     tcg_gen_andi_tl(t0, cpu_gpr[rB(ctx->opcode)], 0x3f);
     tcg_gen_rotl_tl(t0, cpu_gpr[rS(ctx->opcode)], t0);