Re: [Qemu-devel] [PATCH 1/2] target-mips: fix incorrect behaviour for EXTP

[Aurelien Jarno <aurelien@aurel32.net>]

On Mon, May 13, 2013 at 03:20:26PM +0200, Petar Jovanovic wrote:
> From: Petar Jovanovic <petar.jovanovic@imgtec.com>
> 
> The mask for EXTP instruction when size=31 has not been correctly
> calculated.
> 
> The test (mips32-dsp/extp.c) has been extended to include the case that
> triggers the issue.
> 
> Signed-off-by: Petar Jovanovic <petar.jovanovic@imgtec.com>
> ---
>  target-mips/dsp_helper.c         |    3 +--
>  tests/tcg/mips/mips32-dsp/extp.c |   18 ++++++++++++++++++
>  2 files changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/target-mips/dsp_helper.c b/target-mips/dsp_helper.c
> index 9212789..a55f866 100644
> --- a/target-mips/dsp_helper.c
> +++ b/target-mips/dsp_helper.c
> @@ -3415,8 +3415,7 @@ target_ulong helper_extp(target_ulong ac, target_ulong size, CPUMIPSState *env)
>      if (sub >= -1) {
>          acc = ((uint64_t)env->active_tc.HI[ac] << 32) |
>                ((uint64_t)env->active_tc.LO[ac] & MIPSDSP_LLO);
> -        temp = (acc >> (start_pos - size)) &
> -               (((uint32_t)0x01 << (size + 1)) - 1);
> +        temp = (acc >> (start_pos - size)) & (~0U >> (31 - size));
>          set_DSPControl_efi(0, env);
>      } else {
>          set_DSPControl_efi(1, env);
> diff --git a/tests/tcg/mips/mips32-dsp/extp.c b/tests/tcg/mips/mips32-dsp/extp.c
> index 21a67af..b18bdb3 100644
> --- a/tests/tcg/mips/mips32-dsp/extp.c
> +++ b/tests/tcg/mips/mips32-dsp/extp.c
> @@ -40,5 +40,23 @@ int main()
>      dsp = (dsp >> 14) & 0x01;
>      assert(dsp == 1);
>  
> +    ach = 0;
> +    acl = 0x80000001;
> +    dsp = 0x1F;
> +    result = 0x80000001;
> +
> +    __asm
> +        ("wrdsp %1\n\t"
> +         "mthi %2, $ac2\n\t"
> +         "mtlo %3, $ac2\n\t"
> +         "extp %0, $ac2, 0x1F\n\t"
> +         "rddsp %1\n\t"
> +         : "=r"(rt), "+r"(dsp)
> +         : "r"(ach), "r"(acl)
> +        );
> +    dsp = (dsp >> 14) & 0x01;
> +    assert(dsp == 0);
> +    assert(result == rt);
> +
>      return 0;
>  }

Thanks, applied.

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