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From:   Andy Lutomirski <luto@amacapital.net>
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Subject: Re: [PATCH 1/4] x86: add __X32_COND_SYSCALL() macro
Date:   Sat, 19 Sep 2020 10:39:32 -0700
Message-Id: <027BAF5D-1473-4A35-8A58-D80315D52073@amacapital.net>
References: <85F32523-4E9E-443A-A150-10A9E5EB0CE3@zytor.com>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Christoph Hellwig <hch@infradead.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Eric Biederman <ebiederm@xmission.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>, kexec@lists.infradead.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Christoph Hellwig <hch@lst.de>, Brian Gerst <brgerst@gmail.com>
In-Reply-To: <85F32523-4E9E-443A-A150-10A9E5EB0CE3@zytor.com>
To:     hpa@zytor.com
Precedence: bulk


> On Sep 19, 2020, at 10:14 AM, hpa@zytor.com wrote:
>=20
> =EF=BB=BFOn September 19, 2020 9:23:22 AM PDT, Andy Lutomirski <luto@kerne=
l.org> wrote:
>>> On Fri, Sep 18, 2020 at 10:35 PM Christoph Hellwig <hch@infradead.org>
>>> wrote:
>>>=20
>>> On Fri, Sep 18, 2020 at 03:24:36PM +0200, Arnd Bergmann wrote:
>>>> sys_move_pages() is an optional syscall, and once we remove
>>>> the compat version of it in favor of the native one with an
>>>> in_compat_syscall() check, the x32 syscall table refers to
>>>> a __x32_sys_move_pages symbol that may not exist when the
>>>> syscall is disabled.
>>>>=20
>>>> Change the COND_SYSCALL() definition on x86 to also include
>>>> the redirection for x32.
>>>>=20
>>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>>>=20
>>> Adding the x86 maintainers and Brian Gerst.  Brian proposed another
>>> problem to the mess that most of the compat syscall handlers used by
>>> x32 here:
>>>=20
>>>   https://lkml.org/lkml/2020/6/16/664
>>>=20
>>> hpa didn't particularly like it, but with your and my pending series
>>> we'll soon use more native than compat syscalls for x32, so something
>>> will need to change..
>>=20
>> I'm fine with either solution.
>=20
> My main objection was naming. x64 is a widely used synonym for x86-64, and=
 so that is confusing.
>=20
>=20

The way I deal with the syscall wrappers is that I assume the naming makes n=
o sense whatsoever, and I go from there. With this perspective, the patches a=
re neither an improvement nor a worsening of the current situation.

(Similarly, the last column of the tables is useless garbage.  My last attem=
pt to fix that stalled.)=