linux-kernel - Re: [PATCH v2] powerpc: warn on emulation of dcbz instruction in kernel mode

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Message-Id: <163584790970.1845480.2701645430318676678.b4-ty@ellerman.id.au>
Date:   Tue, 02 Nov 2021 21:11:49 +1100
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:     Finn Thain <fthain@...ux-m68k.org>,
        Stan Johnson <userm57@...oo.com>, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v2] powerpc: warn on emulation of dcbz instruction in kernel mode

On Thu, 16 Sep 2021 16:52:09 +0200, Christophe Leroy wrote:
> dcbz instruction shouldn't be used on non-cached memory. Using
> it on non-cached memory can result in alignment exception and
> implies a heavy handling.
> 
> Instead of silentely emulating the instruction and resulting in high
> performance degradation, warn whenever an alignment exception is
> taken in kernel mode due to dcbz, so that the user is made aware that
> dcbz instruction has been used unexpectedly by the kernel.
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc: warn on emulation of dcbz instruction in kernel mode
      https://git.kernel.org/powerpc/c/cbe654c779616807e1e6823c3bdbfe07a10562b8

cheers