linux-kernel - Re: [PATCH] x86/asm/64: do not clear high 32 bits of syscall number when CONFIG_X86

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Message-ID: <CACGkJdsGVwqdE6MqZqG4hxGuqOL5aOeJR+PhLvwcWmfFmjkyyg@mail.gmail.com>
Date:   Thu, 14 Sep 2017 19:40:43 +0000
From:   Eugene Syromyatnikov <evgsyr@...il.com>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        "Dmitry V. Levin" <ldv@...linux.org>
Subject: Re: [PATCH] x86/asm/64: do not clear high 32 bits of syscall number
 when CONFIG_X86_X32=y

On Wed, Sep 13, 2017 at 4:49 PM, Oleg Nesterov <oleg@...hat.com> wrote:
> IOW, why do we want to silently ignore the upper bits in $rax ?

By the way, they are ignored elsewhere, in audit[1] or seccomp[2], for example.

[1] include/linux/audit.h
[2] include/uapi/linux/seccomp.h, definition of struct seccomp_data

-- 
Eugene Syromyatnikov
mailto:evgsyr@...il.com
xmpp:esyr@...ber.{ru|org}