From: "H. Peter Anvin" <hpa@zytor.com>
To: Valdis.Kletnieks@vt.edu
Cc: Andrew Morton <akpm@linux-foundation.org>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Oleg Nesterov <oleg@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Pavel Emelyanov <xemul@parallels.com>,
Andrey Vagin <avagin@openvz.org>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
Glauber Costa <glommer@parallels.com>,
Andi Kleen <andi@firstfloor.org>, Tejun Heo <tj@kernel.org>,
Matt Helsley <matthltc@us.ibm.com>,
Pekka Enberg <penberg@kernel.org>,
Eric Dumazet <eric.dumazet@gmail.com>,
Vasiliy Kulikov <segoon@openwall.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Michal Marek <mmarek@suse.cz>,
Frederic Weisbecker <fweisbec@gmail.com>,
linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>
Subject: Re: + syscalls-x86-add-__nr_kcmp-syscall-v8.patch added to -mm tree
Date: Tue, 10 Apr 2012 17:06:57 -0700 [thread overview]
Message-ID: <4F84CB21.80907@zytor.com> (raw)
In-Reply-To: <7939.1334102329@turing-police.cc.vt.edu>
On 04/10/2012 04:58 PM, Valdis.Kletnieks@vt.edu wrote:
>
> I'm not able to convince myself that "less than" and "greater than"
> mean anything - do we have a good proof that for all v1 and v2, the
> obfuscated pointers have the same ordering as the original
> pointers?
>
No, of course they don't.
That's the point.
The whole point is that kcmp() exports an ordered set, but the
ordering is explicitly and intentionally different than the actual
ordering in memory. It is still valid for sorting, in particular.
> Hmm... consider the simplified example v1 = 5 and v2= 16., and
> cookies[0] is also 16. Then obfus(v1) == 21, and obfus(v2) == 0,
> and the ordering is different. So I'm thinking 0 and 3 are the
> only sane return values?
>
> Or do I need more caffeine?
You need more caffeine. You're thinking about the problem wrong.
-hpa
next prev parent reply other threads:[~2012-04-11 0:08 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-15 14:36 + syscalls-x86-add-__nr_kcmp-syscall-v8.patch added to -mm tree Oleg Nesterov
2012-02-15 15:10 ` Cyrill Gorcunov
2012-02-15 15:38 ` Oleg Nesterov
2012-02-15 16:13 ` Cyrill Gorcunov
2012-02-15 16:22 ` Oleg Nesterov
2012-02-15 17:53 ` Cyrill Gorcunov
2012-02-15 18:43 ` Oleg Nesterov
2012-02-15 19:56 ` Cyrill Gorcunov
2012-02-15 19:57 ` Vasiliy Kulikov
2012-02-15 20:05 ` Cyrill Gorcunov
2012-02-15 20:25 ` Cyrill Gorcunov
2012-02-15 21:09 ` Cyrill Gorcunov
2012-02-15 21:58 ` Cyrill Gorcunov
2012-02-16 14:49 ` Oleg Nesterov
2012-02-16 15:13 ` Cyrill Gorcunov
2012-02-16 16:49 ` Cyrill Gorcunov
2012-02-16 17:40 ` Oleg Nesterov
2012-02-16 17:58 ` Cyrill Gorcunov
2012-02-16 19:03 ` Oleg Nesterov
2012-02-16 19:20 ` H. Peter Anvin
2012-02-16 19:29 ` Cyrill Gorcunov
2012-02-16 19:52 ` Andrew Morton
2012-02-16 20:01 ` Cyrill Gorcunov
2012-02-16 18:21 ` Vasiliy Kulikov
2012-02-16 18:34 ` Cyrill Gorcunov
2012-02-16 18:33 ` Vasiliy Kulikov
2012-02-16 18:49 ` Oleg Nesterov
2012-02-15 18:32 ` Cyrill Gorcunov
2012-02-15 19:06 ` Oleg Nesterov
2012-02-15 19:18 ` Cyrill Gorcunov
2012-02-15 16:06 ` Oleg Nesterov
2012-02-15 16:27 ` Cyrill Gorcunov
2012-04-09 22:10 ` Andrew Morton
2012-04-09 22:24 ` Cyrill Gorcunov
2012-04-09 23:22 ` H. Peter Anvin
2012-04-10 22:37 ` Cyrill Gorcunov
2012-04-10 22:39 ` H. Peter Anvin
2012-04-10 22:48 ` Cyrill Gorcunov
2012-04-10 23:08 ` Oleg Nesterov
2012-04-10 23:32 ` H. Peter Anvin
2012-04-10 23:42 ` Oleg Nesterov
2012-04-11 6:39 ` Cyrill Gorcunov
2012-04-11 18:31 ` Oleg Nesterov
2012-04-11 0:02 ` Valdis.Kletnieks
2012-04-10 3:25 ` Eric W. Biederman
2012-04-10 22:54 ` Cyrill Gorcunov
2012-04-10 23:58 ` Valdis.Kletnieks
2012-04-11 0:06 ` H. Peter Anvin [this message]
-- strict thread matches above, loose matches on Subject: below --
2012-02-14 23:15 akpm
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