linux-kernel - Re: [PATCH 4/8] x86: io: add "memory" clobber to insb/insw/insl/outsb/outsw/outsl

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Message-ID: <CA+55aFxEKPrOphN+Yp85nTCHPg22WqUFm2CsmMSkJ-8dYYSQkg@mail.gmail.com>
Date:   Wed, 19 Jul 2017 12:46:43 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     "the arch/x86 maintainers" <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Borislav Petkov <bp@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [PATCH 4/8] x86: io: add "memory" clobber to insb/insw/insl/outsb/outsw/outsl

On Wed, Jul 19, 2017 at 5:53 AM, Arnd Bergmann <arnd@...db.de> wrote:
>
> I tried to mark the exact input buffer as an output here, but couldn't
> figure it out. As suggested by Linus, marking all memory as clobbered
> however is good enough too. For the outs operations, I also add the
> memory clobber, to force the input to be written to local variables.
> This is probably already guaranteed by the "asm volatile", but it can't
> hurt to do this for symmetry.

Ack, obviously looks fine to me.

                 Linus