From: Al Boldi <a1426z@gawab.com>
To: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Paulo Marques <pmarques@grupopie.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Arjan van de Ven <arjan@infradead.org>,
Frank van Maarseveen <frankvm@frankvm.com>
Subject: Re: [PATCH] x86: Don't randomize stack unless current->personality permits it
Date: Mon, 24 Jul 2006 18:57:46 +0300 [thread overview]
Message-ID: <200607241857.46594.a1426z@gawab.com> (raw)
In-Reply-To: <200607202023.13901.a1426z@gawab.com>
Al Boldi wrote:
> Chuck Ebbert wrote:
> > On Tue, 18 Jul 2006 08:21:45 +0300. Al Boldi wrote:
> > > Going one step further,
> > > with #define arch_stack_align(x) (x)
> > > all blips/hits/weirdness are gone
> > >
> > > Which means that either arch_stack_align isn't necessary at all, or
> > > randomization isn't working as intended.
> > >
> > > Can somebody prove me wrong here?
> >
> > Your program seems highly sensitive to any changes,
>
> Extremely sensitive. You may have noticed the strange repetitions in main
> instead of a for loop. It's like that for a reason: compile semantics.
>
> > $ ./tst.ex
> > &x = 0xbfb32d90, &y = 0xbfb32d98
> > 10 6 10 10 6 10 7 10 10 10 10 10 10 10
>
> With your changes on:
>
> stock kernel, randomize_va_space=0, gcc.322 -Os tstExec.c,
> while :; do ./a.out; done
> &x = 0xbffff874, &y = 0xbffff86c 28 28
> &x = 0xbffff874, &y = 0xbffff86c 27 27
> &x = 0xbffff874, &y = 0xbffff86c 27 27
> &x = 0xbffff874, &y = 0xbffff86c 28 27
> &x = 0xbffff874, &y = 0xbffff86c 27 30
> &x = 0xbffff874, &y = 0xbffff86c 27 29
>
> stock kernel, randomize_va_space=1, gcc.322 -Os tstExec.c,
> while :; do ./a.out; done
> &x = 0xbfe2e614, &y = 0xbfe2e60c 29 28
> &x = 0xbfd6a104, &y = 0xbfd6a0fc 55 56
> &x = 0xbf91d454, &y = 0xbf91d44c 27 27
> &x = 0xbf941e84, &y = 0xbf941e7c 55 56
> &x = 0xbfa75834, &y = 0xbfa7582c 28 27
> &x = 0xbfb58634, &y = 0xbfb5862c 27 30
After closer inspection, it looks like addresses ending with 3c,7c,bc,fc
cause a slowdown on P4, while addresses ending with 1c,3c,5c,7c,9c,bc,dc,fc
cause a slowdown on P2.
Any easy way to instruct the kernel to skip those addresses?
Thanks!
--
Al
next prev parent reply other threads:[~2006-07-24 15:56 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-19 17:02 [PATCH] x86: Don't randomize stack unless current->personality permits it Chuck Ebbert
2006-07-20 17:23 ` Al Boldi
2006-07-24 15:57 ` Al Boldi [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-07-25 0:21 Chuck Ebbert
2006-07-25 4:57 ` Al Boldi
2006-07-16 3:58 Chuck Ebbert
2006-07-16 19:49 ` Al Boldi
2006-07-11 19:57 Al Boldi
2006-07-12 16:03 ` Andi Kleen
2006-07-12 20:12 ` Al Boldi
2006-07-12 20:27 ` Arjan van de Ven
2006-07-12 21:13 ` Al Boldi
2006-07-13 9:44 ` Frank van Maarseveen
2006-07-13 20:51 ` Al Boldi
2006-07-13 20:54 ` Arjan van de Ven
2006-07-15 11:29 ` Al Boldi
2006-07-15 12:22 ` Arjan van de Ven
2006-07-15 14:09 ` Al Boldi
2006-07-15 16:15 ` Arjan van de Ven
2006-07-15 17:39 ` Al Boldi
2006-07-17 15:50 ` Paulo Marques
2006-07-18 5:21 ` Al Boldi
2006-07-11 15:22 Frank van Maarseveen
2006-07-11 20:11 ` Arjan van de Ven
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