I'm using a modified kernel version derived from 2.6.21.7,and the cpu
is octeon cn5860. Strangely I found that , when executing
some instruction in un-executable segment, the system will hang on,
together with console down, and could not response to ping
command.
cn5860 has 16 CPUs, in our system , each non-zero cpu is running a
real-time user-mode process with 99 priority(network
business) , causing non-zero cpus to 100% cpu-usage.
while cpu 0 ,is in charge of coordinating the whole system ,almost to
5~6% cpu-usage.
That is , the following code ,will cause a problem , which hang the
cpu 0, and then hang the whole system:
#include <stdio.h>
#include <stdlib.h>
char stack[8*1024] = {0}; // in un-executable segment
void (*func)(void);
int main()
{
func = (void (*)(void))stack; //convert to function pointer
func(); //cpu will hang
return 0;
}
In my opinion, the code above should generate a page_fault exception ,
and caused SIGSEGV error, however in my
system , it hang on directly.
Any one knows why this happened? Thanks
regards,
wilbur
