Re: [PATCH V2] ARM: SWP emulation: Restore original *data when failed

From: Vladimir Murzin
Date: Tue Dec 08 2015 - 05:23:37 EST


On 15/10/15 10:30, Shengjiu Wang wrote:
> __user_swpX_asm maybe failed in first STREX operation, emulate_swpX
> will try again, but the *data has been changed in first time. which
> causes the result is wrong.
> This patch is to fix this issue. When STREX succeed, change the *data.
> if it fail, *data is not changed.
>
> Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxxxxxxxx>
> ---
> arch/arm/kernel/swp_emulate.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/kernel/swp_emulate.c b/arch/arm/kernel/swp_emulate.c
> index 5b26e7e..c3fe769d 100644
> --- a/arch/arm/kernel/swp_emulate.c
> +++ b/arch/arm/kernel/swp_emulate.c
> @@ -36,10 +36,10 @@
> */
> #define __user_swpX_asm(data, addr, res, temp, B) \
> __asm__ __volatile__( \
> - " mov %2, %1\n" \
> - "0: ldrex"B" %1, [%3]\n" \
> - "1: strex"B" %0, %2, [%3]\n" \
> + "0: ldrex"B" %2, [%3]\n" \
> + "1: strex"B" %0, %1, [%3]\n" \
> " cmp %0, #0\n" \
> + " moveq %1, %2\n" \
> " movne %0, %4\n" \
> "2:\n" \
> " .section .text.fixup,\"ax\"\n" \
>

I wonder what is status of this patch? I see that arm64 counterpart has
landed in mainline, but I didn't manage to track down this one - is it
because it never been submitted to patch system?

Thanks
Vladimir

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