summaryrefslogtreecommitdiffstats
path: root/kernel/tools/perf/arch/x86/tests/rdpmc.c
blob: e7688214c7cf19fc040170b2590d19d8e011b6e8 (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
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/mman.h>
#include <linux/types.h>
#include "perf.h"
#include "debug.h"
#include "tests/tests.h"
#include "cloexec.h"
#include "arch-tests.h"

static u64 rdpmc(unsigned int counter)
{
	unsigned int low, high;

	asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter));

	return low | ((u64)high) << 32;
}

static u64 rdtsc(void)
{
	unsigned int low, high;

	asm volatile("rdtsc" : "=a" (low), "=d" (high));

	return low | ((u64)high) << 32;
}

static u64 mmap_read_self(void *addr)
{
	struct perf_event_mmap_page *pc = addr;
	u32 seq, idx, time_mult = 0, time_shift = 0;
	u64 count, cyc = 0, time_offset = 0, enabled, running, delta;

	do {
		seq = pc->lock;
		barrier();

		enabled = pc->time_enabled;
		running = pc->time_running;

		if (enabled != running) {
			cyc = rdtsc();
			time_mult = pc->time_mult;
			time_shift = pc->time_shift;
			time_offset = pc->time_offset;
		}

		idx = pc->index;
		count = pc->offset;
		if (idx)
			count += rdpmc(idx - 1);

		barrier();
	} while (pc->lock != seq);

	if (enabled != running) {
		u64 quot, rem;

		quot = (cyc >> time_shift);
		rem = cyc & ((1 << time_shift) - 1);
		delta = time_offset + quot * time_mult +
			((rem * time_mult) >> time_shift);

		enabled += delta;
		if (idx)
			running += delta;

		quot = count / running;
		rem = count % running;
		count = quot * enabled + (rem * enabled) / running;
	}

	return count;
}

/*
 * If the RDPMC instruction faults then signal this back to the test parent task:
 */
static void segfault_handler(int sig __maybe_unused,
			     siginfo_t *info __maybe_unused,
			     void *uc __maybe_unused)
{
	exit(-1);
}

static int __test__rdpmc(void)
{
	volatile int tmp = 0;
	u64 i, loops = 1000;
	int n;
	int fd;
	void *addr;
	struct perf_event_attr attr = {
		.type = PERF_TYPE_HARDWARE,
		.config = PERF_COUNT_HW_INSTRUCTIONS,
		.exclude_kernel = 1,
	};
	u64 delta_sum = 0;
        struct sigaction sa;
	char sbuf[STRERR_BUFSIZE];

	sigfillset(&sa.sa_mask);
	sa.sa_sigaction = segfault_handler;
	sigaction(SIGSEGV, &sa, NULL);

	fd = sys_perf_event_open(&attr, 0, -1, -1,
				 perf_event_open_cloexec_flag());
	if (fd < 0) {
		pr_err("Error: sys_perf_event_open() syscall returned "
		       "with %d (%s)\n", fd,
		       strerror_r(errno, sbuf, sizeof(sbuf)));
		return -1;
	}

	addr = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
	if (addr == (void *)(-1)) {
		pr_err("Error: mmap() syscall returned with (%s)\n",
		       strerror_r(errno, sbuf, sizeof(sbuf)));
		goto out_close;
	}

	for (n = 0; n < 6; n++) {
		u64 stamp, now, delta;

		stamp = mmap_read_self(addr);

		for (i = 0; i < loops; i++)
			tmp++;

		now = mmap_read_self(addr);
		loops *= 10;

		delta = now - stamp;
		pr_debug("%14d: %14Lu\n", n, (long long)delta);

		delta_sum += delta;
	}

	munmap(addr, page_size);
	pr_debug("   ");
out_close:
	close(fd);

	if (!delta_sum)
		return -1;

	return 0;
}

int test__rdpmc(void)
{
	int status = 0;
	int wret = 0;
	int ret;
	int pid;

	pid = fork();
	if (pid < 0)
		return -1;

	if (!pid) {
		ret = __test__rdpmc();

		exit(ret);
	}

	wret = waitpid(pid, &status, 0);
	if (wret < 0 || status)
		return -1;

	return 0;
}