FW: Kprobes might be stealing int3

FW: Kprobes might be stealing int3

[Keshavamurthy, Anil S]

I went little further and found why the application is segmentation
fault'ing.

In the kprobes_handler() code, we are checking 
If (*addr != BREAK_INSTRUCTION)  and this is where the 
app is crashing since we are trying to dereference this address 
which is not a linear address.

I would be happy to tryout any fix that any one provides.

Thanks,
Anil
-----Original Message-----
From: Keshavamurthy Anil S [mailto:anil.s.keshavamurthy@intel.com] 
Sent: Thursday, February 23, 2006 12:11 PM
To: Systemtap
Cc: Keshavamurthy, Anil S
Subject: Kprobes might be stealing int3

Hi,
	I tried running the below program on both
x86_64 and i386 and on both architecture,
if the kernel is compiled with CONFIG_KPROBES, 
my below application segmentation faults.

On kernel where CONFIG_KPROBES set to N, the 
same test program passes.

Here goes the test program...
-------------------------
#include <stdlib.h>
#include <signal.h>
 
void my_trap(int sig)
{
 printf("Test passed, all OK\n");
 exit(0);
}
 
int main()
{
 signal(SIGTRAP, my_trap);
 asm volatile (".byte 0xcd,3");
 printf("Stolen interrupt, very bad!\n");
}
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