linux-kernel - Re: [PATCH 1/4] x86: add __X32_COND

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Date:   Sat, 19 Sep 2020 13:45:43 -0400
From:   Brian Gerst <brgerst@...il.com>
To:     "H. Peter Anvin" <hpa@...or.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Christoph Hellwig <hch@...radead.org>,
        Arnd Bergmann <arnd@...db.de>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Eric Biederman <ebiederm@...ssion.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>, kexec@...ts.infradead.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 1/4] x86: add __X32_COND_SYSCALL() macro

An alternative to the patch I proposed earlier would be to use aliases
with the __x32_ prefix for the common syscalls.

--
Brian Gerst

On Sat, Sep 19, 2020 at 1:14 PM <hpa@...or.com> wrote:
>
> On September 19, 2020 9:23:22 AM PDT, Andy Lutomirski <luto@...nel.org> wrote:
> >On Fri, Sep 18, 2020 at 10:35 PM Christoph Hellwig <hch@...radead.org>
> >wrote:
> >>
> >> 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.
> >> >
> >> > Change the COND_SYSCALL() definition on x86 to also include
> >> > the redirection for x32.
> >> >
> >> > Signed-off-by: Arnd Bergmann <arnd@...db.de>
> >>
> >> 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:
> >>
> >>    https://lkml.org/lkml/2020/6/16/664
> >>
> >> 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..
> >
> >I'm fine with either solution.
>
> My main objection was naming. x64 is a widely used synonym for x86-64, and so that is confusing.
>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.