summaryrefslogtreecommitdiffstats
path: root/tools/testing/selftests/prctl/disable-tsc-test.c
blob: f84d4ee111d37bba19fab3b077dadb2073891429 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
// SPDX-License-Identifier: GPL-2.0
/*
 * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
 *
 * Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <inttypes.h>


#include <sys/prctl.h>
#include <linux/prctl.h>

/* Get/set the process' ability to use the timestamp counter instruction */
#ifndef PR_GET_TSC
#define PR_GET_TSC 25
#define PR_SET_TSC 26
# define PR_TSC_ENABLE		1   /* allow the use of the timestamp counter */
# define PR_TSC_SIGSEGV		2   /* throw a SIGSEGV instead of reading the TSC */
#endif

const char *tsc_names[] =
{
	[0] = "[not set]",
	[PR_TSC_ENABLE] = "PR_TSC_ENABLE",
	[PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV",
};

static uint64_t rdtsc(void)
{
uint32_t lo, hi;
/* We cannot use "=A", since this would use %rax on x86_64 */
__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
return (uint64_t)hi << 32 | lo;
}

static void sigsegv_cb(int sig)
{
	int tsc_val = 0;

	printf("[ SIG_SEGV ]\n");
	printf("prctl(PR_GET_TSC, &tsc_val); ");
	fflush(stdout);

	if ( prctl(PR_GET_TSC, &tsc_val) == -1)
		perror("prctl");

	printf("tsc_val == %s\n", tsc_names[tsc_val]);
	printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
	fflush(stdout);
	if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
		perror("prctl");

	printf("rdtsc() == ");
}

int main(void)
{
	int tsc_val = 0;

	signal(SIGSEGV, sigsegv_cb);

	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
	printf("prctl(PR_GET_TSC, &tsc_val); ");
	fflush(stdout);

	if ( prctl(PR_GET_TSC, &tsc_val) == -1)
		perror("prctl");

	printf("tsc_val == %s\n", tsc_names[tsc_val]);
	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
	printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
	fflush(stdout);

	if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
		perror("prctl");

	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
	printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n");
	fflush(stdout);

	if ( prctl(PR_SET_TSC, PR_TSC_SIGSEGV) == -1)
		perror("prctl");

	printf("rdtsc() == ");
	fflush(stdout);
	printf("%llu\n", (unsigned long long)rdtsc());
	fflush(stdout);

	exit(EXIT_SUCCESS);
}

OpenPOWER on IntegriCloud