blob: 81fdd425ab3e583e0543becd2b0d665dc134ab38 [file] [log] [blame]
Erik Bosmanf1326972008-04-11 18:57:22 +02001/*
2 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
3 *
4 * Tests if the control register is updated correctly
5 * at context switches
6 *
7 * Warning: this test will cause a very high load for a few seconds
8 *
9 */
10
11#include <stdio.h>
12#include <stdlib.h>
13#include <unistd.h>
14#include <signal.h>
15#include <inttypes.h>
16#include <wait.h>
17
18
19#include <sys/prctl.h>
20#include <linux/prctl.h>
21
22/* Get/set the process' ability to use the timestamp counter instruction */
23#ifndef PR_GET_TSC
24#define PR_GET_TSC 25
25#define PR_SET_TSC 26
26# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */
27# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */
28#endif
29
Peter Foley0421fc82014-09-25 11:23:15 -070030static uint64_t rdtsc(void)
31{
Erik Bosmanf1326972008-04-11 18:57:22 +020032uint32_t lo, hi;
33/* We cannot use "=A", since this would use %rax on x86_64 */
34__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
35return (uint64_t)hi << 32 | lo;
36}
37
Peter Foley0421fc82014-09-25 11:23:15 -070038static void sigsegv_expect(int sig)
Erik Bosmanf1326972008-04-11 18:57:22 +020039{
40 /* */
41}
42
Peter Foley0421fc82014-09-25 11:23:15 -070043static void segvtask(void)
Erik Bosmanf1326972008-04-11 18:57:22 +020044{
45 if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0)
46 {
47 perror("prctl");
48 exit(0);
49 }
50 signal(SIGSEGV, sigsegv_expect);
51 alarm(10);
52 rdtsc();
53 fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n");
54 exit(0);
55}
56
57
Peter Foley0421fc82014-09-25 11:23:15 -070058static void sigsegv_fail(int sig)
Erik Bosmanf1326972008-04-11 18:57:22 +020059{
60 fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n");
61 exit(0);
62}
63
Peter Foley0421fc82014-09-25 11:23:15 -070064static void rdtsctask(void)
Erik Bosmanf1326972008-04-11 18:57:22 +020065{
66 if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0)
67 {
68 perror("prctl");
69 exit(0);
70 }
71 signal(SIGSEGV, sigsegv_fail);
72 alarm(10);
73 for(;;) rdtsc();
74}
75
76
77int main(int argc, char **argv)
78{
79 int n_tasks = 100, i;
80
81 fprintf(stderr, "[No further output means we're allright]\n");
82
83 for (i=0; i<n_tasks; i++)
84 if (fork() == 0)
85 {
86 if (i & 1)
87 segvtask();
88 else
89 rdtsctask();
90 }
91
92 for (i=0; i<n_tasks; i++)
93 wait(NULL);
94
95 exit(0);
96}
97