Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751531AbcDRAre (ORCPT <rfc822;w@1wt.eu>);
	Sun, 17 Apr 2016 20:47:34 -0400
Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45297 "EHLO
	shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK)
	by vger.kernel.org with ESMTP id S1751047AbcDRArd (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Sun, 17 Apr 2016 20:47:33 -0400
Date: Mon, 18 Apr 2016 01:47:31 +0100
From: Ben Hutchings <ben@decadent.org.uk>
To: Andy Lutomirski <luto@kernel.org>
Cc: X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Message-ID: <20160418004731.GB3348@decadent.org.uk>
References: <1460940317.9121.56.camel@decadent.org.uk>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="bCsyhTFzCvuiizWE"
Content-Disposition: inline
In-Reply-To: <1460940317.9121.56.camel@decadent.org.uk>
User-Agent: Mutt/1.5.23 (2014-03-12)
X-SA-Exim-Connect-IP: <locally generated>
X-SA-Exim-Mail-From: ben@decadent.org.uk
Subject: [PATCH] x86/entry/x32: Check top 32 bits of syscall number on the
 fast path
X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000)
X-SA-Exim-Scanned: Yes (on shadbolt.decadent.org.uk)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 2095
Lines: 61


--bCsyhTFzCvuiizWE
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

We've always masked off the top 32 bits when x32 is enabled, but
hopefully no-one relies on that.  Now that the slow path is in C, we
check all the bits there, regardless of whether x32 is enabled.  Let's
make the fast path consistent with it.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/entry/entry_64.S | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 858b555e274b..17ba2ca9b24d 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -190,12 +190,10 @@ entry_SYSCALL_64_fastpath:
 	 */
 	TRACE_IRQS_ON
 	ENABLE_INTERRUPTS(CLBR_NONE)
-#if __SYSCALL_MASK =3D=3D ~0
-	cmpq	$__NR_syscall_max, %rax
-#else
-	andl	$__SYSCALL_MASK, %eax
-	cmpl	$__NR_syscall_max, %eax
+#if __SYSCALL_MASK !=3D ~0
+	andq	$__SYSCALL_MASK, %rax
 #endif
+	cmpq	$__NR_syscall_max, %rax
 	ja	1f				/* return -ENOSYS (already in pt_regs->ax) */
 	movq	%r10, %rcx
=20

--bCsyhTFzCvuiizWE
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: Digital signature

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
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=ZiFQ
-----END PGP SIGNATURE-----

--bCsyhTFzCvuiizWE--