[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH for-2.6] target-sparc: fix ldstub sign-extension
From: |
Artyom Tarasenko |
Subject: |
Re: [Qemu-devel] [PATCH for-2.6] target-sparc: fix ldstub sign-extension bug |
Date: |
Sat, 9 Apr 2016 14:49:59 +0200 |
On Sat, Apr 9, 2016 at 1:43 PM, Mark Cave-Ayland
<address@hidden> wrote:
> ldstub [addr], reg incorrectly reads a signed byte from memory which causes
> problems in the 32-bit Solaris mutex code. Here the byte value being read is
> 0xff which is incorrectly sign-extended to 0xffffffff before being written
> back
> to the target register causing lock detection to behave incorrectly.
>
> This fixes the intermittent hangs and MUTEX_HELD warnings issued to the
> console when running 32-bit Solaris images under qemu-system-sparc.
>
> With thanks to Joseph Dery for providing a condensed test image to
> consistently
> reproduce the problem on demand, and Martin Husemann for allowing me access to
> real hardware for comparison.
>
> Signed-off-by: Mark Cave-Ayland <address@hidden>
Reviewed-By: Artyom Tarasenko <address@hidden>
> ---
> target-sparc/translate.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target-sparc/translate.c b/target-sparc/translate.c
> index 58572c3..7998ff5 100644
> --- a/target-sparc/translate.c
> +++ b/target-sparc/translate.c
> @@ -4670,7 +4670,7 @@ static void disas_sparc_insn(DisasContext * dc,
> unsigned int insn)
> TCGv r_const;
>
> gen_address_mask(dc, cpu_addr);
> - tcg_gen_qemu_ld8s(cpu_val, cpu_addr, dc->mem_idx);
> + tcg_gen_qemu_ld8u(cpu_val, cpu_addr, dc->mem_idx);
> r_const = tcg_const_tl(0xff);
> tcg_gen_qemu_st8(r_const, cpu_addr, dc->mem_idx);
> tcg_temp_free(r_const);
> --
> 1.7.10.4
>
--
Regards,
Artyom Tarasenko
SPARC and PPC PReP under qemu blog: http://tyom.blogspot.com/search/label/qemu