1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright 2019 ARM Ltd.
4 *
5 * Generic implementation of update_vsyscall and update_vsyscall_tz.
6 *
7 * Based on the x86 specific implementation.
8 */
9
10#include <linux/hrtimer.h>
11#include <linux/timekeeper_internal.h>
12#include <vdso/datapage.h>
13#include <vdso/helpers.h>
14#include <vdso/vsyscall.h>
15
16#include "timekeeping_internal.h"
17
18static inline void update_vdso_data(struct vdso_data *vdata,
19				    struct timekeeper *tk)
20{
21	struct vdso_timestamp *vdso_ts;
22	u64 nsec, sec;
23
24	vdata[CS_HRES_COARSE].cycle_last	= tk->tkr_mono.cycle_last;
25	vdata[CS_HRES_COARSE].mask		= tk->tkr_mono.mask;
26	vdata[CS_HRES_COARSE].mult		= tk->tkr_mono.mult;
27	vdata[CS_HRES_COARSE].shift		= tk->tkr_mono.shift;
28	vdata[CS_RAW].cycle_last		= tk->tkr_raw.cycle_last;
29	vdata[CS_RAW].mask			= tk->tkr_raw.mask;
30	vdata[CS_RAW].mult			= tk->tkr_raw.mult;
31	vdata[CS_RAW].shift			= tk->tkr_raw.shift;
32
33	/* CLOCK_MONOTONIC */
34	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC];
35	vdso_ts->sec	= tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
36
37	nsec = tk->tkr_mono.xtime_nsec;
38	nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
39	while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
40		nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
41		vdso_ts->sec++;
42	}
43	vdso_ts->nsec	= nsec;
44
45	/* Copy MONOTONIC time for BOOTTIME */
46	sec	= vdso_ts->sec;
47	/* Add the boot offset */
48	sec	+= tk->monotonic_to_boot.tv_sec;
49	nsec	+= (u64)tk->monotonic_to_boot.tv_nsec << tk->tkr_mono.shift;
50
51	/* CLOCK_BOOTTIME */
52	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME];
53	vdso_ts->sec	= sec;
54
55	while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
56		nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
57		vdso_ts->sec++;
58	}
59	vdso_ts->nsec	= nsec;
60
61	/* CLOCK_MONOTONIC_RAW */
62	vdso_ts		= &vdata[CS_RAW].basetime[CLOCK_MONOTONIC_RAW];
63	vdso_ts->sec	= tk->raw_sec;
64	vdso_ts->nsec	= tk->tkr_raw.xtime_nsec;
65
66	/* CLOCK_TAI */
67	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI];
68	vdso_ts->sec	= tk->xtime_sec + (s64)tk->tai_offset;
69	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec;
70}
71
72void update_vsyscall(struct timekeeper *tk)
73{
74	struct vdso_data *vdata = __arch_get_k_vdso_data();
75	struct vdso_timestamp *vdso_ts;
76	s32 clock_mode;
77	u64 nsec;
78
79	/* copy vsyscall data */
80	vdso_write_begin(vdata);
81
82	clock_mode = tk->tkr_mono.clock->vdso_clock_mode;
83	vdata[CS_HRES_COARSE].clock_mode	= clock_mode;
84	vdata[CS_RAW].clock_mode		= clock_mode;
85
86	/* CLOCK_REALTIME also required for time() */
87	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
88	vdso_ts->sec	= tk->xtime_sec;
89	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec;
90
91	/* CLOCK_REALTIME_COARSE */
92	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
93	vdso_ts->sec	= tk->xtime_sec;
94	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
95
96	/* CLOCK_MONOTONIC_COARSE */
97	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE];
98	vdso_ts->sec	= tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
99	nsec		= tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
100	nsec		= nsec + tk->wall_to_monotonic.tv_nsec;
101	vdso_ts->sec	+= __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
102
103	/*
104	 * Read without the seqlock held by clock_getres().
105	 * Note: No need to have a second copy.
106	 */
107	WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution);
108
109	/*
110	 * If the current clocksource is not VDSO capable, then spare the
111	 * update of the high resolution parts.
112	 */
113	if (clock_mode != VDSO_CLOCKMODE_NONE)
114		update_vdso_data(vdata, tk);
115
116	__arch_update_vsyscall(vdata, tk);
117
118	vdso_write_end(vdata);
119
120	__arch_sync_vdso_data(vdata);
121}
122
123void update_vsyscall_tz(void)
124{
125	struct vdso_data *vdata = __arch_get_k_vdso_data();
126
127	vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest;
128	vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime;
129
130	__arch_sync_vdso_data(vdata);
131}
132
133/**
134 * vdso_update_begin - Start of a VDSO update section
135 *
136 * Allows architecture code to safely update the architecture specific VDSO
137 * data. Disables interrupts, acquires timekeeper lock to serialize against
138 * concurrent updates from timekeeping and invalidates the VDSO data
139 * sequence counter to prevent concurrent readers from accessing
140 * inconsistent data.
141 *
142 * Returns: Saved interrupt flags which need to be handed in to
143 * vdso_update_end().
144 */
145unsigned long vdso_update_begin(void)
146{
147	struct vdso_data *vdata = __arch_get_k_vdso_data();
148	unsigned long flags;
149
150	raw_spin_lock_irqsave(&timekeeper_lock, flags);
151	vdso_write_begin(vdata);
152	return flags;
153}
154
155/**
156 * vdso_update_end - End of a VDSO update section
157 * @flags:	Interrupt flags as returned from vdso_update_begin()
158 *
159 * Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data
160 * synchronization if the architecture requires it, drops timekeeper lock
161 * and restores interrupt flags.
162 */
163void vdso_update_end(unsigned long flags)
164{
165	struct vdso_data *vdata = __arch_get_k_vdso_data();
166
167	vdso_write_end(vdata);
168	__arch_sync_vdso_data(vdata);
169	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
170}
171