summaryrefslogtreecommitdiff
path: root/kernel/time/vsyscall.c
blob: 5ee0f77094107486752338021a7e22210bdbec1d (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2019 ARM Ltd.
 *
 * Generic implementation of update_vsyscall and update_vsyscall_tz.
 *
 * Based on the x86 specific implementation.
 */

#include <linux/hrtimer.h>
#include <linux/timekeeper_internal.h>
#include <vdso/datapage.h>
#include <vdso/helpers.h>
#include <vdso/vsyscall.h>

static inline void update_vdso_data(struct vdso_data *vdata,
				    struct timekeeper *tk)
{
	struct vdso_timestamp *vdso_ts;
	u64 nsec, sec;

	vdata[CS_HRES_COARSE].cycle_last	= tk->tkr_mono.cycle_last;
	vdata[CS_HRES_COARSE].mask		= tk->tkr_mono.mask;
	vdata[CS_HRES_COARSE].mult		= tk->tkr_mono.mult;
	vdata[CS_HRES_COARSE].shift		= tk->tkr_mono.shift;
	vdata[CS_RAW].cycle_last		= tk->tkr_raw.cycle_last;
	vdata[CS_RAW].mask			= tk->tkr_raw.mask;
	vdata[CS_RAW].mult			= tk->tkr_raw.mult;
	vdata[CS_RAW].shift			= tk->tkr_raw.shift;

	/* CLOCK_REALTIME */
	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
	vdso_ts->sec	= tk->xtime_sec;
	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec;

	/* CLOCK_MONOTONIC */
	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC];
	vdso_ts->sec	= tk->xtime_sec + tk->wall_to_monotonic.tv_sec;

	nsec = tk->tkr_mono.xtime_nsec;
	nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
	while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
		nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
		vdso_ts->sec++;
	}
	vdso_ts->nsec	= nsec;

	/* Copy MONOTONIC time for BOOTTIME */
	sec	= vdso_ts->sec;
	/* Add the boot offset */
	sec	+= tk->monotonic_to_boot.tv_sec;
	nsec	+= (u64)tk->monotonic_to_boot.tv_nsec << tk->tkr_mono.shift;

	/* CLOCK_BOOTTIME */
	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME];
	vdso_ts->sec	= sec;

	while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
		nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
		vdso_ts->sec++;
	}
	vdso_ts->nsec	= nsec;

	/* CLOCK_MONOTONIC_RAW */
	vdso_ts		= &vdata[CS_RAW].basetime[CLOCK_MONOTONIC_RAW];
	vdso_ts->sec	= tk->raw_sec;
	vdso_ts->nsec	= tk->tkr_raw.xtime_nsec;

	/* CLOCK_TAI */
	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI];
	vdso_ts->sec	= tk->xtime_sec + (s64)tk->tai_offset;
	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec;

	/*
	 * Read without the seqlock held by clock_getres().
	 * Note: No need to have a second copy.
	 */
	WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution);
}

void update_vsyscall(struct timekeeper *tk)
{
	struct vdso_data *vdata = __arch_get_k_vdso_data();
	struct vdso_timestamp *vdso_ts;
	u64 nsec;

	if (__arch_update_vdso_data()) {
		/*
		 * Some architectures might want to skip the update of the
		 * data page.
		 */
		return;
	}

	/* copy vsyscall data */
	vdso_write_begin(vdata);

	vdata[CS_HRES_COARSE].clock_mode	= __arch_get_clock_mode(tk);
	vdata[CS_RAW].clock_mode		= __arch_get_clock_mode(tk);

	/* CLOCK_REALTIME_COARSE */
	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
	vdso_ts->sec	= tk->xtime_sec;
	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;

	/* CLOCK_MONOTONIC_COARSE */
	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE];
	vdso_ts->sec	= tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
	nsec		= tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
	nsec		= nsec + tk->wall_to_monotonic.tv_nsec;
	vdso_ts->sec	+= __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);

	update_vdso_data(vdata, tk);

	__arch_update_vsyscall(vdata, tk);

	vdso_write_end(vdata);

	__arch_sync_vdso_data(vdata);
}

void update_vsyscall_tz(void)
{
	struct vdso_data *vdata = __arch_get_k_vdso_data();

	vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest;
	vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime;

	__arch_sync_vdso_data(vdata);
}