linux-kernel - Re: powerpc: set used_vsr/used_vr/used_spe in sigreturn path when MSR bits are active

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Date:   Tue, 13 Sep 2016 22:16:38 +1000 (AEST)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Simon Guo <wei.guo.simon@...il.com>
Cc:     Michael Neuling <mikey@...ling.org>,
        Amanieu d'Antras <amanieu@...il.com>,
        Simon Guo <wei.guo.simon@...il.com>,
        linux-kernel@...r.kernel.org, Paul Mackerras <paulus@...ba.org>,
        Anton Blanchard <anton@...ba.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linuxppc-dev@...ts.ozlabs.org, Cyril Bur <cyrilbur@...il.com>
Subject: Re: powerpc: set used_vsr/used_vr/used_spe in sigreturn path when MSR bits are active

On Tue, 2016-26-07 at 08:06:01 UTC, Simon Guo wrote:
> From: Simon Guo <wei.guo.simon@...il.com>
> 
> Normally, when MSR[VSX/VR/SPE] bits = 1, the used_vsr/used_vr/used_spe
> bit have already been set. However signal frame locates at user space
> and it is controlled by user application. It is up to kernel to make
> sure used_vsr/used_vr/used_spe(in kernel)=1 and consistent with MSR
> bits.
> 
> For example, CRIU application, who utilizes sigreturn to restore
> checkpointed process, will lead to the case where MSR[VSX] bit is
> active in signal frame, but used_vsx bit is not set. (the same applies
> to VR/SPE).
> 
> This patch will reinforce this at kernel by always setting used_* bit
> when MSR related bits are active in signal frame and we are doing
> sigreturn.
> 
> This patch is based on Ben's Proposal.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Signed-off-by: Simon Guo <wei.guo.simon@...il.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/e1c0d66fcb179a1737b3d5cc11

cheers