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To: Anton Blanchard <anton@ozlabs.org>, benh@kernel.crashing.org,
 paulus@samba.org, aneesh.kumar@linux.vnet.ibm.com, acsawdey@linux.vnet.ibm.com
From: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [1/3] powerpc: Avoid load hit store in __giveup_fpu() and
 __giveup_altivec()
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Date: Wed, 15 Jun 2016 22:39:10 +1000 (AEST)
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On Sun, 2016-29-05 at 12:03:50 UTC, Anton Blanchard wrote:
> From: Anton Blanchard <anton@samba.org>
> 
> In both __giveup_fpu() and __giveup_altivec() we make two modifications
> to tsk->thread.regs->msr. gcc decides to do a read/modify/write of
> each change, so we end up with a load hit store:
> 
>         ld      r9,264(r10)
>         rldicl  r9,r9,50,1
>         rotldi  r9,r9,14
>         std     r9,264(r10)
> ...
>         ld      r9,264(r10)
>         rldicl  r9,r9,40,1
>         rotldi  r9,r9,24
>         std     r9,264(r10)
> 
> Fix this by using a temporary.
> 
> Signed-off-by: Anton Blanchard <anton@samba.org>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/8eb9803723a14fd12675641b95

cheers