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
25 const char *tsc_names[] =
26 {
27 [0] = "[not set]",
28 [PR_TSC_ENABLE] = "PR_TSC_ENABLE",
29 [PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV",
30 };
31
rdtsc(void)32 static uint64_t rdtsc(void)
33 {
34 uint32_t lo, hi;
35 /* We cannot use "=A", since this would use %rax on x86_64 */
36 __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
37 return (uint64_t)hi << 32 | lo;
38 }
39
sigsegv_cb(int sig)40 static 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
main(void)60 int main(void)
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