From: Andi Kleen <ak@suse.de>
To: Andrea Arcangeli <andrea@cpushare.com>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>
Subject: Re: disable tsc with seccomp
Date: Sat, 5 Nov 2005 16:37:44 +0100 [thread overview]
Message-ID: <200511051637.44432.ak@suse.de> (raw)
In-Reply-To: <20051105134727.GF18861@opteron.random>
On Saturday 05 November 2005 14:47, Andrea Arcangeli wrote:
> Hello,
>
> This changeset is backing out an useful feature I implemented some month
> ago:
>
> http://kernel.org/hg/linux-2.6/?cs=2fd4e5f089df
>
> Anything that can strengthen security is needed, the covert channels are
> theoretically possible and this is a fact, you don't need hyperthreading
> for that.
It was useless, you can get exactly the same information by using RDPMC
on perfctr 0 which always runs the NMI watchdog and counts all cycles too.
And even with that I don't want to have such checks in the context switch
for something that is at best theoretical. Letting it in would open the
floodgates for making the context switch really slow long term.
-Andi
next prev parent reply other threads:[~2005-11-05 15:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-05 13:47 disable tsc with seccomp Andrea Arcangeli
2005-11-05 15:37 ` Andi Kleen [this message]
2005-11-05 16:07 ` Andrea Arcangeli
2005-11-05 16:12 ` Andi Kleen
2005-11-05 16:31 ` Andrea Arcangeli
2005-11-05 17:04 ` Andi Kleen
2005-11-06 1:55 ` Andrea Arcangeli
2005-11-21 16:43 ` Andrea Arcangeli
2005-11-21 17:05 ` Andi Kleen
2005-11-21 17:16 ` Andrea Arcangeli
2005-11-21 17:24 ` Andi Kleen
2005-11-21 17:38 ` Andrea Arcangeli
2005-11-21 18:40 ` Andrea Arcangeli
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