linux-kernel - Re: [RFC 1/2] powerpc/32: Unset MSR RI in exception epilogs

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Message-ID: <20161213191514.GJ30845@gate.crashing.org>
Date:   Tue, 13 Dec 2016 13:15:14 -0600
From:   Segher Boessenkool <segher@...nel.crashing.org>
To:     Christophe Leroy <christophe.leroy@....fr>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Scott Wood <oss@...error.net>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC 1/2] powerpc/32: Unset MSR RI in exception epilogs

On Tue, Dec 13, 2016 at 07:19:41PM +0100, Christophe Leroy wrote:
> At exception prologs, once SRR0 and SRR1 have been saved, MSR RI is
> set to mark the interrupt as recoverable.
> 
> MSR RI has to be unset before writing into SRR0 and SRR1 at exception
> epilogs.

Why?  What goes wrong without this?  Etc.


Segher