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Date:   Fri, 23 Oct 2020 13:59:58 -0700
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Subject: Re: [PATCH] x86/uaccess: fix code generation in put_user()
To:     Linus Torvalds <torvalds@linux-foundation.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>
CC:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        the arch/x86 maintainers <x86@kernel.org>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
From:   hpa@zytor.com
Message-ID: <8820745F-E761-42E6-8A70-7B04EE70692C@zytor.com>
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On October 23, 2020 1:55:22 PM PDT, Linus Torvalds <torvalds@linux-foundati=
on=2Eorg> wrote:
>Thanks, applied=2E
>
>On Fri, Oct 23, 2020 at 1:32 PM Rasmus Villemoes
><linux@rasmusvillemoes=2Edk> wrote:
>>
>> I'm wondering if one would also need to make __ptr_pu and __ret_pu
>> explicitly "%"_ASM_CX"=2E
>
>No, the "c"/"0" thing is much better, and makes it properly atomic wrt
>the actual asm=2E
>
>As mentioned to Andy, the "register asm()" thing is not uncommon and
>often useful, but when you can specify the register directly in asm,
>that's certainly simpler and more straightforward and preferred=2E
>
>              Linus

There is no same reason to mess around with hacks when we are talking abou=
t dx:ax, though=2E We have to do pretty ugly hacks when other register pair=
s are involved, but "A" is there for a reason=2E _ASM_AX64 maybe=2E=2E=2E
--=20
Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E