On 15/10/15 09:57, Russell King - ARM Linux wrote: > On Thu, Oct 15, 2015 at 04:36:31PM +0800, Shengjiu Wang wrote: >> On Thu, Oct 15, 2015 at 09:24:17AM +0100, Russell King - ARM Linux wrote: >>> On Wed, Oct 14, 2015 at 10:51:17AM +0800, 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 >>>> cause the result is wrong. So need to recover the *data when failed. >>>> >>>> Signed-off-by: Shengjiu Wang <shengjiu.w...@freescale.com> >>>> --- >>>> arch/arm/kernel/swp_emulate.c | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff --git a/arch/arm/kernel/swp_emulate.c b/arch/arm/kernel/swp_emulate.c >>>> index 5b26e7e..c61fbf92 100644 >>>> --- a/arch/arm/kernel/swp_emulate.c >>>> +++ b/arch/arm/kernel/swp_emulate.c >>>> @@ -41,6 +41,7 @@ >>>> "1: strex"B" %0, %2, [%3]\n" \ >>>> " cmp %0, #0\n" \ >>>> " movne %0, %4\n" \ >>>> + " movne %1, %2\n" \ >>>> "2:\n" \ >>>> " .section .text.fixup,\"ax\"\n" \ >>>> " .align 2\n" \ >>> >>> I think I'd prefer this to be: >>> >>> __asm__ __volatile__( \ >>> "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" \ >>> >>> so that we're not loading into %1 (an in-out non-temporary) but rather >>> loading it into a temporary - and only overwriting the saved register >>> value if the swap succeeds. >>> >>> Thanks. >> >> I am ok with your change. Need I send another patch for this change? or will >> you send it by yourself? > > Please send a new patch, thanks. >
We might need the same change for arm64 counterpart (see arch/arm64/kernel/armv8_deprecated.c). Vladimir -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
