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generic, x86: add tests for prctl PR_GET_TSC and PR_SET_TSC

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This patch adds three tests that test whether the PR_GET_TSC and
PR_SET_TSC commands have the desirable effect.

The tests check whether the control register is updated correctly
at context switches and try to discover bugs while enabling/disabling
the timestamp counter.

Signed-off-by: Erik Bosman <ejbosman@cs.vu.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Erik Bosman 2008-04-11 18:57:22 +02:00 • committed by Ingo Molnar
parent 529e25f646
commit f132697326
3 changed files with 285 additions and 0 deletions
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94
Documentation/prctl/disable-tsc-test.c Normal file
View file

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/*
* Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
*
* Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <inttypes.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
const char *tsc_names[] =
{
[0] = "[not set]",
[PR_TSC_ENABLE] = "PR_TSC_ENABLE",
[PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV",
};
uint64_t rdtsc() {
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;
}
void sigsegv_cb(int sig)
{
int tsc_val = 0;
printf("[ SIG_SEGV ]\n");
printf("prctl(PR_GET_TSC, &tsc_val); ");
fflush(stdout);
if ( prctl(PR_GET_TSC, &tsc_val) == -1)
perror("prctl");
printf("tsc_val == %s\n", tsc_names[tsc_val]);
printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
fflush(stdout);
if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
perror("prctl");
printf("rdtsc() == ");
}
int main(int argc, char **argv)
{
int tsc_val = 0;
signal(SIGSEGV, sigsegv_cb);
printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
printf("prctl(PR_GET_TSC, &tsc_val); ");
fflush(stdout);
if ( prctl(PR_GET_TSC, &tsc_val) == -1)
perror("prctl");
printf("tsc_val == %s\n", tsc_names[tsc_val]);
printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
fflush(stdout);
if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
perror("prctl");
printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n");
fflush(stdout);
if ( prctl(PR_SET_TSC, PR_TSC_SIGSEGV) == -1)
perror("prctl");
printf("rdtsc() == ");
fflush(stdout);
printf("%llu\n", (unsigned long long)rdtsc());
fflush(stdout);
exit(EXIT_SUCCESS);
}