Commit | Line | Data |
---|---|---|
f1326973 EB |
1 | /* |
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 | ||
30 | uint64_t rdtsc() { | |
31 | uint32_t lo, hi; | |
32 | /* We cannot use "=A", since this would use %rax on x86_64 */ | |
33 | __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi)); | |
34 | return (uint64_t)hi << 32 | lo; | |
35 | } | |
36 | ||
37 | void sigsegv_expect(int sig) | |
38 | { | |
39 | /* */ | |
40 | } | |
41 | ||
42 | void segvtask(void) | |
43 | { | |
44 | if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0) | |
45 | { | |
46 | perror("prctl"); | |
47 | exit(0); | |
48 | } | |
49 | signal(SIGSEGV, sigsegv_expect); | |
50 | alarm(10); | |
51 | rdtsc(); | |
52 | fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n"); | |
53 | exit(0); | |
54 | } | |
55 | ||
56 | ||
57 | void sigsegv_fail(int sig) | |
58 | { | |
59 | fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n"); | |
60 | exit(0); | |
61 | } | |
62 | ||
63 | void rdtsctask(void) | |
64 | { | |
65 | if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0) | |
66 | { | |
67 | perror("prctl"); | |
68 | exit(0); | |
69 | } | |
70 | signal(SIGSEGV, sigsegv_fail); | |
71 | alarm(10); | |
72 | for(;;) rdtsc(); | |
73 | } | |
74 | ||
75 | ||
76 | int main(int argc, char **argv) | |
77 | { | |
78 | int n_tasks = 100, i; | |
79 | ||
80 | fprintf(stderr, "[No further output means we're allright]\n"); | |
81 | ||
82 | for (i=0; i<n_tasks; i++) | |
83 | if (fork() == 0) | |
84 | { | |
85 | if (i & 1) | |
86 | segvtask(); | |
87 | else | |
88 | rdtsctask(); | |
89 | } | |
90 | ||
91 | for (i=0; i<n_tasks; i++) | |
92 | wait(NULL); | |
93 | ||
94 | exit(0); | |
95 | } | |
96 |