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linux-next/Documentation/prctl/disable-tsc-test.c
Mahesh Khanwalkar f0cd147e61 Documentation: Fix int/unsigned int comparison
Signed int - unsigned int comparison fixed in mpssd, prctl, ptp, and
timers in Documentation. In places where 'int argc' and 'const char
**argv' are not used, they are replaced with void

Documentation/mic/mpssd/mpssd.c: Fixed comparison in sum_iovec_len and
disp_iovec

Documentation/prctl/disable-tsc-ctxt-sw-stress-test.c: main signature
changed to void, as parameters 'argc' and 'argv' are never used

Documentation/prctl/disable-tsc-on-off-stress-test.c: main signature
changed to void

Documentation/prctl/disable-tsc-test.c: main signature changed to void

Documentation/ptp/testptp.c: Sign comparison fix
Documentation/timers/hpet_example.c: Sign comparision fix

Signed-off-by: Mahesh Khanwalkar <maheshkhanwalkar@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2016-02-17 14:09:43 -07:00

96 lines
2.1 KiB
C

/*
* 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",
};
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;
}
static 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(void)
{
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);
}