From: Jeff Law <law@redhat.com>
To: David Miller <davem@davemloft.net>
Cc: matz@suse.de, jkosina@suse.cz, torvalds@linux-foundation.org,
walters@verbum.org, jack@suse.cz, linux-kernel@vger.kernel.org,
linux-ia64@vger.kernel.org, dsterba@suse.cz, ptesarik@suse.cz,
rguenther@suse.de, gcc@gcc.gnu.org
Subject: Re: Memory corruption due to word sharing
Date: Wed, 01 Feb 2012 18:45:57 +0000 [thread overview]
Message-ID: <4F298865.5000409@redhat.com> (raw)
In-Reply-To: <20120201.130905.1131458895704793597.davem@davemloft.net>
On 02/01/2012 11:09 AM, David Miller wrote:
> From: Michael Matz<matz@suse.de>
> Date: Wed, 1 Feb 2012 18:41:05 +0100 (CET)
>
>> One problem is that it's not a new problem, GCC emitted similar code since
>> about forever, and still they turned up only now (well, probably because
>> ia64 is dead, but sparc64 should have similar problems).
>
> Indeed, on sparc64 it does do the silly 64-bit access too:
>
> wrong:
> ldx [%o0+8], %g2
> sethi %hi(2147483648), %g1
> or %g2, %g1, %g1
> jmp %o7+8
> stx %g1, [%o0+8]
>
> Personally I've avoided C bitfields like the plague in any code I've
> written.
Torvald Riegel & I were told that was kernel policy when we brought up
the upcoming bitfield semantic changes with some of the linux kernel
folks last year.
Regardless of the kernel team's policy WRT bitfields, I believe fixing
the semantics to avoid creation of data races in bitfields is going to
be important. I'm hoping Aldy can return to that task soon and he and
Richi can come to some agreement on the implementation with gcc-4.8 as a
target.
jeff
next prev parent reply other threads:[~2012-02-01 18:45 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 15:19 Memory corruption due to word sharing Jan Kara
2012-02-01 15:34 ` Markus Trippelsdorf
2012-02-01 16:37 ` Colin Walters
2012-02-01 16:56 ` Linus Torvalds
2012-02-01 17:11 ` Jiri Kosina
2012-02-01 17:37 ` Linus Torvalds
2012-02-01 17:41 ` Michael Matz
2012-02-01 18:09 ` David Miller
2012-02-01 18:45 ` Jeff Law [this message]
2012-02-01 19:09 ` Linus Torvalds
2012-02-02 15:51 ` Jeff Garzik
2012-02-01 18:57 ` Linus Torvalds
2012-02-01 19:04 ` Peter Bergner
2012-02-01 18:52 ` Linus Torvalds
2012-02-02 9:35 ` Richard Guenther
2012-02-02 9:37 ` Richard Guenther
2012-02-02 13:43 ` Michael Matz
2012-02-01 16:41 ` Linus Torvalds
2012-02-01 17:42 ` Torvald Riegel
2012-02-01 19:40 ` Jakub Jelinek
2012-02-01 20:01 ` Linus Torvalds
2012-02-01 20:16 ` Jakub Jelinek
2012-02-01 20:44 ` Linus Torvalds
2012-02-02 15:58 ` Aldy Hernandez
2012-02-02 16:28 ` Michael Matz
2012-02-02 17:51 ` Linus Torvalds
2012-02-01 20:19 ` Linus Torvalds
2012-02-02 9:46 ` Richard Guenther
2012-02-01 19:44 ` Boehm, Hans
2012-02-01 19:54 ` Jeff Law
2012-02-01 19:47 ` Linus Torvalds
2012-02-01 19:58 ` Alan Cox
2012-02-01 20:41 ` Torvald Riegel
2012-02-01 20:59 ` Linus Torvalds
2012-02-01 21:24 ` Torvald Riegel
2012-02-01 21:55 ` Linus Torvalds
2012-02-01 21:25 ` Boehm, Hans
2012-02-01 22:27 ` Linus Torvalds
2012-02-01 22:45 ` Paul E. McKenney
2012-02-01 23:11 ` Linus Torvalds
2012-02-02 18:42 ` Paul E. McKenney
2012-02-02 19:08 ` Linus Torvalds
2012-02-02 19:37 ` Paul E. McKenney
2012-02-03 16:38 ` Andrew MacLeod
2012-02-03 17:16 ` Linus Torvalds
2012-02-03 19:16 ` Andrew MacLeod
2012-02-03 20:00 ` Linus Torvalds
2012-02-03 20:19 ` Paul E. McKenney
2012-02-06 15:38 ` Torvald Riegel
2012-02-10 19:27 ` Richard Henderson
2012-02-02 11:19 ` Ingo Molnar
2012-02-01 21:04 ` Boehm, Hans
2012-02-02 9:28 ` Bernd Petrovitsch
2012-02-01 17:08 ` Torvald Riegel
2012-02-01 17:29 ` Linus Torvalds
2012-02-01 20:53 ` Torvald Riegel
2012-02-01 21:20 ` Linus Torvalds
2012-02-01 21:37 ` Torvald Riegel
2012-02-01 22:18 ` Boehm, Hans
2012-02-01 17:52 ` Dennis Clarke
2012-02-02 11:11 ` James Courtier-Dutton
2012-02-02 11:24 ` Richard Guenther
2012-02-02 11:13 ` David Sterba
2012-02-02 11:23 ` Richard Guenther
2012-02-03 6:45 ` DJ Delorie
2012-02-03 9:37 ` Richard Guenther
2012-02-03 10:03 ` Matthew Gretton-Dann
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