]>
Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
f1326973 EB |
2 | /* |
3 | * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...) | |
4 | * | |
5 | * Tests if the control register is updated correctly | |
6 | * when set with prctl() | |
7 | * | |
8 | * Warning: this test will cause a very high load for a few seconds | |
9 | * | |
10 | */ | |
11 | ||
12 | #include <stdio.h> | |
13 | #include <stdlib.h> | |
14 | #include <unistd.h> | |
15 | #include <signal.h> | |
16 | #include <inttypes.h> | |
17 | #include <wait.h> | |
18 | ||
19 | ||
20 | #include <sys/prctl.h> | |
21 | #include <linux/prctl.h> | |
22 | ||
23 | /* Get/set the process' ability to use the timestamp counter instruction */ | |
24 | #ifndef PR_GET_TSC | |
25 | #define PR_GET_TSC 25 | |
26 | #define PR_SET_TSC 26 | |
27 | # define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */ | |
28 | # define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */ | |
29 | #endif | |
30 | ||
31 | /* snippet from wikipedia :-) */ | |
32 | ||
0421fc83 PF |
33 | static uint64_t rdtsc(void) |
34 | { | |
f1326973 EB |
35 | uint32_t lo, hi; |
36 | /* We cannot use "=A", since this would use %rax on x86_64 */ | |
37 | __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi)); | |
38 | return (uint64_t)hi << 32 | lo; | |
39 | } | |
40 | ||
41 | int should_segv = 0; | |
42 | ||
0421fc83 | 43 | static void sigsegv_cb(int sig) |
f1326973 EB |
44 | { |
45 | if (!should_segv) | |
46 | { | |
47 | fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n"); | |
48 | exit(0); | |
49 | } | |
50 | if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0) | |
51 | { | |
52 | perror("prctl"); | |
53 | exit(0); | |
54 | } | |
55 | should_segv = 0; | |
56 | ||
57 | rdtsc(); | |
58 | } | |
59 | ||
0421fc83 | 60 | static void task(void) |
f1326973 EB |
61 | { |
62 | signal(SIGSEGV, sigsegv_cb); | |
63 | alarm(10); | |
64 | for(;;) | |
65 | { | |
66 | rdtsc(); | |
67 | if (should_segv) | |
68 | { | |
69 | fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n"); | |
70 | exit(0); | |
71 | } | |
72 | if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0) | |
73 | { | |
74 | perror("prctl"); | |
75 | exit(0); | |
76 | } | |
77 | should_segv = 1; | |
78 | } | |
79 | } | |
80 | ||
81 | ||
f0cd147e | 82 | int main(void) |
f1326973 EB |
83 | { |
84 | int n_tasks = 100, i; | |
85 | ||
86 | fprintf(stderr, "[No further output means we're allright]\n"); | |
87 | ||
88 | for (i=0; i<n_tasks; i++) | |
89 | if (fork() == 0) | |
90 | task(); | |
91 | ||
92 | for (i=0; i<n_tasks; i++) | |
93 | wait(NULL); | |
94 | ||
95 | exit(0); | |
96 | } | |
97 |