From: Chuck Ebbert <76306.1226@compuserve.com>
To: Al Boldi <a1426z@gawab.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: Wed, 19 Jul 2006 13:02:29 -0400 [thread overview]
Message-ID: <200607191305_MC3-1-C56F-6E4F@compuserve.com> (raw)
In-Reply-To: <200607180821.45346.a1426z@gawab.com>
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, e.g. with the
following code, results with and without the commented lines are
different. (I changed i to 5555555 because my cpu is slower than
yours and changed main() to call it 10 times.) This on an AMD
Turion64 1.6GHz running an i386 kernel with stock arch_stack_align()
and randomize_va_space == 1.
void fn()
{
double x = 0.0, y = 0.0;
long i = 5555555;
// static int printed = 0;
//
// if (!printed) {
// printed++;
// printf("&x = %p, &y = %p\n", &x, &y);
// }
elapsed(1);
while (i--)
fn2(&x,&y);
printf("%4lu ", elapsed(0));
}
$ ./tst.ex
&x = 0xbfb32d90, &y = 0xbfb32d98
10 6 10 10 6 10 7 10 10 10 10 10 10 10 10 10 10 10 10 10 msec
$ ./tst.ex
7 10 6 6 6 6 10 10 6 6 6 10 10 6 6 6 6 10 6 6 msec
BTW when compiled with gcc 4.1.1 using -O3 it just prints all zeros,
so I had to use 3.3.3.
--
Chuck
next reply other threads:[~2006-07-19 17:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-19 17:02 Chuck Ebbert [this message]
2006-07-20 17:23 ` [PATCH] x86: Don't randomize stack unless current->personality permits it Al Boldi
2006-07-24 15:57 ` Al Boldi
-- 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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