Re: trouble trapping SEGV on 2.6.11.2 & 2.6.12-rc4

From: Richard B. Johnson
Date: Tue May 24 2005 - 16:19:10 EST



To jump out of signal handlers, you now need sigsetjmp() and
siglongjmp().


On Tue, 24 May 2005, Clifford T. Matthews wrote:

The included program dies with a SEGV under 2.6.11.2 and 2.6.12-rc4.
It doesn't die under 2.4.25. I compiled the kernels myself. The
distribution is Fedora Core release 3, with glibc 2.3.5.

I don't have any earlier 2.6 kernels to test it on, so I have no idea
when this bug first appeared.

I only skim LKML through fa.linux.kernel, so please CC me on any reply
that I should see.

--Cliff Matthews <ctm@xxxxxxxx>
+1 505 363 5754 Cell

#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <stdbool.h>
#include <assert.h>
#include <setjmp.h>
#include <signal.h>

static jmp_buf segv_return;

static void
segv_handler (int signum_ignored __attribute__((unused)))
{
longjmp (segv_return, 1);
}

int
main (void)
{
volatile char *volatile addr;
volatile int n_failures;

addr = (void *) 0x10000L;
n_failures = 0;

signal (SIGSEGV, segv_handler);
if (setjmp (segv_return) != 0)
++n_failures;
else
*addr;

printf ("n_failures = %d\n", n_failures);

if (setjmp (segv_return) != 0)
++n_failures;
else
*addr;

printf ("n_failures = %d\n", n_failures);

return 0;
}
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Cheers,
Dick Johnson
Penguin : Linux version 2.6.11.9 on an i686 machine (5537.79 BogoMips).
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