1/*
2 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
3 *
4 * Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC
5 */
6
7#include <stdio.h>
8#include <stdlib.h>
9#include <unistd.h>
10#include <signal.h>
11#include <inttypes.h>
12
13
14#include <sys/prctl.h>
15#include <linux/prctl.h>
16
17/* Get/set the process' ability to use the timestamp counter instruction */
18#ifndef PR_GET_TSC
19#define PR_GET_TSC 25
20#define PR_SET_TSC 26
21# define PR_TSC_ENABLE		1   /* allow the use of the timestamp counter */
22# define PR_TSC_SIGSEGV		2   /* throw a SIGSEGV instead of reading the TSC */
23#endif
24
25const char *tsc_names[] =
26{
27	[0] = "[not set]",
28	[PR_TSC_ENABLE] = "PR_TSC_ENABLE",
29	[PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV",
30};
31
32static uint64_t rdtsc(void)
33{
34uint32_t lo, hi;
35/* We cannot use "=A", since this would use %rax on x86_64 */
36__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
37return (uint64_t)hi << 32 | lo;
38}
39
40static void sigsegv_cb(int sig)
41{
42	int tsc_val = 0;
43
44	printf("[ SIG_SEGV ]\n");
45	printf("prctl(PR_GET_TSC, &tsc_val); ");
46	fflush(stdout);
47
48	if ( prctl(PR_GET_TSC, &tsc_val) == -1)
49		perror("prctl");
50
51	printf("tsc_val == %s\n", tsc_names[tsc_val]);
52	printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
53	fflush(stdout);
54	if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
55		perror("prctl");
56
57	printf("rdtsc() == ");
58}
59
60int main(int argc, char **argv)
61{
62	int tsc_val = 0;
63
64	signal(SIGSEGV, sigsegv_cb);
65
66	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
67	printf("prctl(PR_GET_TSC, &tsc_val); ");
68	fflush(stdout);
69
70	if ( prctl(PR_GET_TSC, &tsc_val) == -1)
71		perror("prctl");
72
73	printf("tsc_val == %s\n", tsc_names[tsc_val]);
74	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
75	printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
76	fflush(stdout);
77
78	if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
79		perror("prctl");
80
81	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
82	printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n");
83	fflush(stdout);
84
85	if ( prctl(PR_SET_TSC, PR_TSC_SIGSEGV) == -1)
86		perror("prctl");
87
88	printf("rdtsc() == ");
89	fflush(stdout);
90	printf("%llu\n", (unsigned long long)rdtsc());
91	fflush(stdout);
92
93	exit(EXIT_SUCCESS);
94}
95
96