1#include <stdbool.h>
2#include <errno.h>
3
4#include <linux/perf_event.h>
5
6#include "../../perf.h"
7#include <linux/types.h>
8#include "../../util/debug.h"
9#include "../../util/tsc.h"
10#include "tsc.h"
11
12int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
13			     struct perf_tsc_conversion *tc)
14{
15	bool cap_user_time_zero;
16	u32 seq;
17	int i = 0;
18
19	while (1) {
20		seq = pc->lock;
21		rmb();
22		tc->time_mult = pc->time_mult;
23		tc->time_shift = pc->time_shift;
24		tc->time_zero = pc->time_zero;
25		cap_user_time_zero = pc->cap_user_time_zero;
26		rmb();
27		if (pc->lock == seq && !(seq & 1))
28			break;
29		if (++i > 10000) {
30			pr_debug("failed to get perf_event_mmap_page lock\n");
31			return -EINVAL;
32		}
33	}
34
35	if (!cap_user_time_zero)
36		return -EOPNOTSUPP;
37
38	return 0;
39}
40
41u64 rdtsc(void)
42{
43	unsigned int low, high;
44
45	asm volatile("rdtsc" : "=a" (low), "=d" (high));
46
47	return low | ((u64)high) << 32;
48}
49