From: Jakub Jelinek <jakub@redhat.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Chris Lattner <clattner@apple.com>, Michael Matz <matz@suse.de>,
Richard Guenther <richard.guenther@gmail.com>,
Joe Buck <Joe.Buck@synopsys.com>, Jan Hubicka <hubicka@ucw.cz>,
Aurelien Jarno <aurelien@aurel32.net>,
linux-kernel@vger.kernel.org, gcc@gcc.gnu.org
Subject: Re: RELEASE BLOCKER: Linux doesn't follow x86/x86-64 ABI wrt direction flag
Date: Thu, 6 Mar 2008 04:17:09 -0500 [thread overview]
Message-ID: <20080306091708.GE24887@devserv.devel.redhat.com> (raw)
In-Reply-To: <47CF44E7.3020106@zytor.com>
On Wed, Mar 05, 2008 at 05:12:07PM -0800, H. Peter Anvin wrote:
> It's a kernel bug, and it needs to be fixed. The discussion is about
> what to do in the meantime.
While it is known that 32-bit glibc memmove and also <string.h> inlines
for memmove and memrchr use std; some string op; cld;, 64-bit glibc doesn't
ever use std instruction. gcc itself never generates std instruction.
So, I've disassebled the whole Fedora/x86_64 distro (64-bit binaries/shared
libraries/archives/object files, unpacked over 12000 rpms) to see how common
is std insn in 64-bit code. The only positive hits were the kernel
(/boot/xen-syms-2.6.21.7-2897.fc9 in particular, whatever that is) and
libpolyml.so.1.0.0 (polyml-libs - this one has handwritten assembly in
NASM), though I had to skim through some false positives (0xfd byte
appearing in data within code sections, but it is easy to see if 0xfd
is surrounded by invalid or nonsensical instructions that it is actually
data). The conclusion is that DF=1 in x86_64 64-bit code is extremely rare.
Therefore, if we decide to apply a workaround for the kernel bug in gcc
(I'm not convinced we should), it should be IMNSHO limited to 32-bit code.
Jakub
next prev parent reply other threads:[~2008-03-06 9:18 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-05 15:30 Linux doesn't follow x86/x86-64 ABI wrt direction flag Aurelien Jarno
2008-03-05 16:00 ` H. Peter Anvin
2008-03-05 19:58 ` Joe Buck
2008-03-05 20:23 ` Aurelien Jarno
2008-03-05 20:38 ` Michael Matz
2008-03-05 20:42 ` Joe Buck
2008-03-05 20:49 ` Jan Hubicka
2008-03-05 21:02 ` Michael Matz
2008-03-05 21:20 ` RELEASE BLOCKER: " Joe Buck
2008-03-05 21:32 ` Richard Guenther
2008-03-05 21:34 ` H. Peter Anvin
2008-03-05 21:40 ` Richard Guenther
2008-03-05 22:16 ` David Miller
2008-03-05 22:37 ` Joe Buck
2008-03-05 22:51 ` Michael Matz
2008-03-05 22:58 ` H. Peter Anvin
2008-03-05 23:07 ` Michael Matz
2008-03-05 23:10 ` David Miller
2008-03-05 23:16 ` Joe Buck
2008-03-05 23:12 ` Olivier Galibert
2008-03-05 21:43 ` Joe Buck
2008-03-05 21:44 ` Richard Guenther
[not found] ` <738B72DB-A1D6-43F8-813A-E49688D05771@apple.com>
2008-03-05 21:59 ` Michael Matz
2008-03-05 22:13 ` Adrian Bunk
2008-03-05 22:21 ` David Miller
2008-03-05 23:13 ` Olivier Galibert
2008-03-06 0:36 ` Chris Lattner
2008-03-06 0:47 ` H. Peter Anvin
[not found] ` <578FCA7D-D7A6-44F6-9310-4A97C13CDCBE@apple.com>
2008-03-06 1:12 ` H. Peter Anvin
2008-03-06 9:17 ` Jakub Jelinek [this message]
2008-03-06 13:51 ` Olivier Galibert
2008-03-06 14:03 ` Paolo Bonzini
2008-03-06 14:12 ` Olivier Galibert
2008-03-06 14:15 ` Andrew Haley
2008-03-06 17:58 ` Joe Buck
2008-03-06 18:10 ` Olivier Galibert
2008-03-06 18:13 ` Paolo Bonzini
2008-03-06 18:31 ` Jack Lloyd
2008-03-06 18:35 ` Andrew Pinski
2008-03-06 19:44 ` Paolo Bonzini
2008-03-06 19:43 ` Paolo Bonzini
2008-03-06 20:16 ` Jack Lloyd
2008-03-06 21:37 ` Artur Skawina
2008-03-06 15:09 ` Robert Dewar
2008-03-06 15:37 ` NightStrike
2008-03-06 15:43 ` H.J. Lu
2008-03-06 15:50 ` H. Peter Anvin
2008-03-06 16:23 ` Jakub Jelinek
2008-03-06 16:27 ` İsmail Dönmez
2008-03-06 16:58 ` H.J. Lu
2008-03-06 17:06 ` H. Peter Anvin
2008-03-06 17:14 ` H.J. Lu
2008-03-06 17:17 ` H. Peter Anvin
2008-03-06 17:34 ` H.J. Lu
2008-03-06 19:35 ` Robert Dewar
2008-03-06 17:18 ` Robert Dewar
2008-03-06 17:19 ` H. Peter Anvin
2008-03-06 19:25 ` Robert Dewar
2008-03-06 20:37 ` H. Peter Anvin
2008-03-07 8:28 ` Florian Weimer
2008-03-07 8:00 ` Andreas Jaeger
2008-03-06 15:57 ` Robert Dewar
2008-03-06 16:29 ` Paolo Bonzini
2008-03-06 17:18 ` H. Peter Anvin
2008-03-06 16:14 ` Artur Skawina
2008-03-06 0:49 ` Aurelien Jarno
2008-03-05 22:05 ` H. Peter Anvin
2008-03-06 2:11 ` Krzysztof Halasa
2008-03-06 8:44 ` Andi Kleen
2008-03-06 9:01 ` Jakub Jelinek
2008-03-06 15:20 ` H. Peter Anvin
2008-03-05 21:45 ` Aurelien Jarno
2008-03-05 21:43 ` Andrew Pinski
2008-03-05 21:43 ` Michael Matz
2008-03-05 22:12 ` Joe Buck
2008-03-05 22:17 ` David Miller
2008-03-05 23:17 ` Olivier Galibert
2008-03-05 23:21 ` David Daney
2008-03-06 14:06 ` Olivier Galibert
2008-03-08 19:10 ` Alexandre Oliva
2008-03-05 21:07 ` H. Peter Anvin
2008-03-05 20:44 ` H. Peter Anvin
2008-03-05 20:52 ` Aurelien Jarno
2008-03-05 21:23 ` David Miller
2008-03-06 9:53 ` Andrew Haley
2008-03-06 11:45 ` Andi Kleen
2008-03-06 12:06 ` Richard Guenther
2008-03-06 17:34 ` Joe Buck
2008-03-06 20:54 ` Richard Guenther
2008-03-06 20:56 ` H. Peter Anvin
2008-03-06 22:06 ` Andi Kleen
2008-03-07 4:56 ` Chris Lattner
2008-03-07 14:09 ` Michael Matz
2008-03-06 9:45 ` Mikael Pettersson
2008-03-05 16:56 ` H.J. Lu
2008-03-05 18:14 ` [PATCH] x86: Clear DF before calling signal handler Aurelien Jarno
2008-03-05 18:17 ` H. Peter Anvin
2008-03-06 9:21 ` Ingo Molnar
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