From: Oleg Nesterov <oleg@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
Eugene Syromyatnikov <evgsyr@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/asm/64: do not clear high 32 bits of syscall number when CONFIG_X86_X32=y
Date: Fri, 15 Sep 2017 18:12:43 +0200 [thread overview]
Message-ID: <20170915161243.GA778@redhat.com> (raw)
In-Reply-To: <20170914202114.GA16764@altlinux.org>
On 09/14, Dmitry V. Levin wrote:
>
> On Wed, Sep 13, 2017 at 06:49:21PM +0200, Oleg Nesterov wrote:
>
> > do_syscall_64() does "nr & __SYSCALL_MASK" unconditionally,
>
> yes
>
> > this clears the upper bits, no?
>
> Why? As "nr" is of type "unsigned long" and __SYSCALL_MASK is either
> (~(__X32_SYSCALL_BIT)) or (~0), that is, an integer with the sign bit set,
Yes, thanks for correcting me, it is "int" but somehow I thought it is
"unsigned int".
Oleg.
next prev parent reply other threads:[~2017-09-15 16:12 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-12 22:57 [PATCH] x86/asm/64: do not clear high 32 bits of syscall number when CONFIG_X86_X32=y Dmitry V. Levin
2017-09-13 16:49 ` Oleg Nesterov
2017-09-14 19:40 ` Eugene Syromyatnikov
2017-09-14 20:24 ` Dmitry V. Levin
2017-09-14 20:21 ` Dmitry V. Levin
2017-09-15 16:12 ` Oleg Nesterov [this message]
2017-09-14 21:05 ` Andy Lutomirski
2017-09-14 21:33 ` Dmitry V. Levin
2017-09-14 21:38 ` Andy Lutomirski
2017-09-15 5:31 ` Ingo Molnar
2017-09-15 5:46 ` hpa
2017-09-17 16:45 ` Dmitry V. Levin
2017-09-15 5:47 ` hpa
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