0421fc837c
Signed-off-by: Peter Foley <pefoley2@pefoley.com> Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
97 lines
1.7 KiB
C
97 lines
1.7 KiB
C
/*
|
|
* Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
|
|
*
|
|
* Tests if the control register is updated correctly
|
|
* when set with prctl()
|
|
*
|
|
* Warning: this test will cause a very high load for a few seconds
|
|
*
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <signal.h>
|
|
#include <inttypes.h>
|
|
#include <wait.h>
|
|
|
|
|
|
#include <sys/prctl.h>
|
|
#include <linux/prctl.h>
|
|
|
|
/* Get/set the process' ability to use the timestamp counter instruction */
|
|
#ifndef PR_GET_TSC
|
|
#define PR_GET_TSC 25
|
|
#define PR_SET_TSC 26
|
|
# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */
|
|
# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */
|
|
#endif
|
|
|
|
/* snippet from wikipedia :-) */
|
|
|
|
static uint64_t rdtsc(void)
|
|
{
|
|
uint32_t lo, hi;
|
|
/* We cannot use "=A", since this would use %rax on x86_64 */
|
|
__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
|
|
return (uint64_t)hi << 32 | lo;
|
|
}
|
|
|
|
int should_segv = 0;
|
|
|
|
static void sigsegv_cb(int sig)
|
|
{
|
|
if (!should_segv)
|
|
{
|
|
fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n");
|
|
exit(0);
|
|
}
|
|
if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0)
|
|
{
|
|
perror("prctl");
|
|
exit(0);
|
|
}
|
|
should_segv = 0;
|
|
|
|
rdtsc();
|
|
}
|
|
|
|
static void task(void)
|
|
{
|
|
signal(SIGSEGV, sigsegv_cb);
|
|
alarm(10);
|
|
for(;;)
|
|
{
|
|
rdtsc();
|
|
if (should_segv)
|
|
{
|
|
fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n");
|
|
exit(0);
|
|
}
|
|
if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0)
|
|
{
|
|
perror("prctl");
|
|
exit(0);
|
|
}
|
|
should_segv = 1;
|
|
}
|
|
}
|
|
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
int n_tasks = 100, i;
|
|
|
|
fprintf(stderr, "[No further output means we're allright]\n");
|
|
|
|
for (i=0; i<n_tasks; i++)
|
|
if (fork() == 0)
|
|
task();
|
|
|
|
for (i=0; i<n_tasks; i++)
|
|
wait(NULL);
|
|
|
|
exit(0);
|
|
}
|
|
|