From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Nicholas Piggin <npiggin@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: Re: powerpc/64s: return more carefully from sreset NMI
Date: Wed, 4 Apr 2018 02:03:40 +1000 (AEST) [thread overview]
Message-ID: <40Fv5m40Rxz9s3c@ozlabs.org> (raw)
In-Reply-To: <20180326150103.22941-1-npiggin@gmail.com>
On Mon, 2018-03-26 at 15:01:03 UTC, Nicholas Piggin wrote:
> System Reset, being an NMI, must return more carefully than other
> interrupts. It has traditionally returned via the nromal return
> from exception path, but that has a number of problems.
>
> - r13 does not get restored if returning to kernel. This is for
> interrupts which may cause a context switch, which sreset will
> never do. Interrupting OPAL (which uses a different r13) is one
> place where this causes breakage.
>
> - It may cause several other problems returning to kernel with
> preempt or TIF_EMULATE_STACK_STORE if it hits at the wrong time.
>
> It's safer just to have a simple restore and return, like machine
> check which is the other NMI.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/15b4dd7981496f51c5f9262a5e0761
cheers
prev parent reply other threads:[~2018-04-03 16:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-26 15:01 [PATCH] powerpc/64s: return more carefully from sreset NMI Nicholas Piggin
2018-04-03 16:03 ` Michael Ellerman [this message]
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