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From: Ingo Molnar <mingo@kernel.org>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Fengguang Wu <fengguang.wu@intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH] gcc4: Add 'asm goto' miscompilation quirk
Date: Thu, 10 Oct 2013 10:45:35 +0200	[thread overview]
Message-ID: <20131010084535.GA10620@gmail.com> (raw)
In-Reply-To: <20131010083107.GZ30970@tucnak.zalov.cz>


* Jakub Jelinek <jakub@redhat.com> wrote:

> On Thu, Oct 10, 2013 at 10:24:30AM +0200, Ingo Molnar wrote:
> > Something like the patch below? (Totally untested and all that.)
> > 
> > Notes:
> > 
> > - If the bug is fixed in 4.8.3 then the version check can be sharpened
> >   from 99999 to 40803.
> 
> The bug is likely going to be fixed already for 4.8.2 (to be released
> next week or so).
> 
> > - I'd really prefer this quirk versus having to add the extra barrier to 
> >   the label, as it makes the actual usage sites a lot less painful.
> 
> Please check how much it bloats the generated code.

on Linus's latest tree plain 'asm goto' is only rarely used, so the size 
impact of the patch, on x86-64 defconfig, is zero:

 vmlinux:
     text           data     bss      dec            hex filename
 11166823        1448024 1187840 13802687         d29cbf vmlinux.before
 11166823        1448024 1187840 13802687         d29cbf vmlinux.after
 1f7c3c1fd71b4b1327965bcfbc7a77fb  vmlinux.before
 3b246add801bc170e47096b712942395  vmlinux.after

Using GCC 4.8.1.

> Also, for the bitops patch, you probably want an asm_volatile_goto variant.

Also, for mutex_64.h - good point, will fix that.

Thanks,

	Ingo

  reply	other threads:[~2013-10-10  8:45 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-05 23:44 [x86] BUG: unable to handle kernel paging request at 00740060 Fengguang Wu
2013-10-05 23:47 ` [x86] BUG: unable to handle kernel paging request at 08000060 Fengguang Wu
2013-10-06  7:27   ` Mike Galbraith
2013-10-06  7:36     ` Fengguang Wu
2013-10-07  8:49   ` Peter Zijlstra
2013-10-07  9:17     ` Fengguang Wu
2013-10-07  9:36       ` Peter Zijlstra
2013-10-07  9:46         ` Fengguang Wu
2013-10-07  8:55 ` [x86] BUG: unable to handle kernel paging request at 00740060 Peter Zijlstra
2013-10-07  9:08   ` Peter Zijlstra
2013-10-07 11:32     ` Fengguang Wu
2013-10-07  9:27   ` Fengguang Wu
2013-10-07 18:47 ` Linus Torvalds
2013-10-08  7:51   ` Fengguang Wu
2013-10-08 16:21     ` Linus Torvalds
2013-10-08 17:15       ` [x86] BUG: unable to handle kernel NULL pointer dereference at (null) Fengguang Wu
2013-10-08 17:31         ` Linus Torvalds
2013-10-09  1:09           ` Fengguang Wu
2013-10-09  1:33             ` Linus Torvalds
2013-10-08 18:51       ` [x86] BUG: unable to handle kernel paging request at 00740060 Oleg Nesterov
2013-10-08 19:05         ` Jakub Jelinek
2013-10-08 19:20           ` Linus Torvalds
2013-10-08 19:34             ` Linus Torvalds
2013-10-08 19:35           ` Oleg Nesterov
2013-10-08 19:49             ` Linus Torvalds
2013-10-09  1:43           ` Mike Galbraith
2013-10-08 19:05         ` Linus Torvalds
2013-10-08 16:46     ` Oleg Nesterov
2013-10-08 14:34   ` Oleg Nesterov
2013-10-09  8:04     ` Fengguang Wu
2013-10-09 12:19       ` Fengguang Wu
2013-10-09 12:21         ` Fengguang Wu
2013-10-09 12:27         ` Peter Zijlstra
2013-10-09 12:52           ` Ingo Molnar
2013-10-09 17:18             ` Ingo Molnar
2013-10-10  2:15               ` Mike Galbraith
2013-10-09 12:56           ` Fengguang Wu
2013-10-09 12:43       ` Oleg Nesterov
2013-10-09 14:07         ` Peter Zijlstra
2013-10-09 14:17           ` Oleg Nesterov
2013-10-09 14:32           ` Ingo Molnar
2013-10-09 14:33           ` Peter Zijlstra
2013-10-09 14:46             ` Peter Zijlstra
2013-10-09 18:16               ` Jakub Jelinek
2013-10-09 18:54                 ` Linus Torvalds
2013-10-09 19:02                 ` Peter Zijlstra
2013-10-09 19:08                   ` Jakub Jelinek
2013-10-10  6:22                     ` Ingo Molnar
2013-10-10  6:51                       ` Jakub Jelinek
2013-10-10  8:04                         ` Jakub Jelinek
2013-10-10  8:24                           ` [PATCH] gcc4: Add 'asm goto' miscompilation quirk Ingo Molnar
2013-10-10  8:31                             ` Jakub Jelinek
2013-10-10  8:45                               ` Ingo Molnar [this message]
2013-10-10  8:55                                 ` [PATCH, -v2] compiler/gcc4: Add quirk for 'asm goto' miscompilation bug Ingo Molnar
2013-10-10 11:56                                   ` Peter Zijlstra
2013-10-10 12:32                                     ` Jakub Jelinek
2013-10-10 13:10                                       ` Peter Zijlstra
2013-10-10 15:04                                         ` Ingo Molnar
2013-10-10 14:04                               ` [PATCH] gcc4: Add 'asm goto' miscompilation quirk Richard Henderson
2013-10-10 14:27                                 ` Jakub Jelinek
2013-10-10 15:12                                   ` [PATCH, -v3] compiler/gcc4: Add quirk for 'asm goto' miscompilation bug Ingo Molnar
2013-10-10 16:15                                     ` Richard Henderson
2013-10-10 16:49                                       ` Ingo Molnar
2013-10-11  4:35                                     ` Fengguang Wu
2013-10-11  5:46                                       ` Ingo Molnar
2013-10-11  6:51                                         ` Fengguang Wu
2013-10-11  9:30                                           ` Fengguang Wu
2013-10-12 17:03                                             ` Ingo Molnar
2013-10-10  8:34                             ` [PATCH] gcc4: Add 'asm goto' miscompilation quirk Ingo Molnar

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