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
update_vdso_time_data(struct vdso_time_data * vdata,struct timekeeper * tk)18 static inline void update_vdso_time_data(struct vdso_time_data *vdata, struct timekeeper *tk)
19 {
20 struct vdso_clock *vc = vdata->clock_data;
21 struct vdso_timestamp *vdso_ts;
22 u64 nsec, sec;
23
24 vc[CS_HRES_COARSE].cycle_last = tk->tkr_mono.cycle_last;
25 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
26 vc[CS_HRES_COARSE].max_cycles = tk->tkr_mono.clock->max_cycles;
27 #endif
28 vc[CS_HRES_COARSE].mask = tk->tkr_mono.mask;
29 vc[CS_HRES_COARSE].mult = tk->tkr_mono.mult;
30 vc[CS_HRES_COARSE].shift = tk->tkr_mono.shift;
31 vc[CS_RAW].cycle_last = tk->tkr_raw.cycle_last;
32 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
33 vc[CS_RAW].max_cycles = tk->tkr_raw.clock->max_cycles;
34 #endif
35 vc[CS_RAW].mask = tk->tkr_raw.mask;
36 vc[CS_RAW].mult = tk->tkr_raw.mult;
37 vc[CS_RAW].shift = tk->tkr_raw.shift;
38
39 /* CLOCK_MONOTONIC */
40 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC];
41 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
42
43 nsec = tk->tkr_mono.xtime_nsec;
44 nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
45 while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
46 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
47 vdso_ts->sec++;
48 }
49 vdso_ts->nsec = nsec;
50
51 /* Copy MONOTONIC time for BOOTTIME */
52 sec = vdso_ts->sec;
53 /* Add the boot offset */
54 sec += tk->monotonic_to_boot.tv_sec;
55 nsec += (u64)tk->monotonic_to_boot.tv_nsec << tk->tkr_mono.shift;
56
57 /* CLOCK_BOOTTIME */
58 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME];
59 vdso_ts->sec = sec;
60
61 while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
62 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
63 vdso_ts->sec++;
64 }
65 vdso_ts->nsec = nsec;
66
67 /* CLOCK_MONOTONIC_RAW */
68 vdso_ts = &vc[CS_RAW].basetime[CLOCK_MONOTONIC_RAW];
69 vdso_ts->sec = tk->raw_sec;
70 vdso_ts->nsec = tk->tkr_raw.xtime_nsec;
71
72 /* CLOCK_TAI */
73 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_TAI];
74 vdso_ts->sec = tk->xtime_sec + (s64)tk->tai_offset;
75 vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
76 }
77
update_vsyscall(struct timekeeper * tk)78 void update_vsyscall(struct timekeeper *tk)
79 {
80 struct vdso_time_data *vdata = vdso_k_time_data;
81 struct vdso_clock *vc = vdata->clock_data;
82 struct vdso_timestamp *vdso_ts;
83 s32 clock_mode;
84 u64 nsec;
85
86 /* copy vsyscall data */
87 vdso_write_begin(vdata);
88
89 clock_mode = tk->tkr_mono.clock->vdso_clock_mode;
90 vc[CS_HRES_COARSE].clock_mode = clock_mode;
91 vc[CS_RAW].clock_mode = clock_mode;
92
93 /* CLOCK_REALTIME also required for time() */
94 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
95 vdso_ts->sec = tk->xtime_sec;
96 vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
97
98 /* CLOCK_REALTIME_COARSE */
99 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
100 vdso_ts->sec = tk->xtime_sec;
101 vdso_ts->nsec = tk->coarse_nsec;
102
103 /* CLOCK_MONOTONIC_COARSE */
104 vdso_ts = &vc[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE];
105 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
106 nsec = tk->coarse_nsec;
107 nsec = nsec + tk->wall_to_monotonic.tv_nsec;
108 vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
109
110 /*
111 * Read without the seqlock held by clock_getres().
112 */
113 WRITE_ONCE(vdata->hrtimer_res, hrtimer_resolution);
114
115 /*
116 * If the current clocksource is not VDSO capable, then spare the
117 * update of the high resolution parts.
118 */
119 if (clock_mode != VDSO_CLOCKMODE_NONE)
120 update_vdso_time_data(vdata, tk);
121
122 __arch_update_vsyscall(vdata);
123
124 vdso_write_end(vdata);
125
126 __arch_sync_vdso_time_data(vdata);
127 }
128
update_vsyscall_tz(void)129 void update_vsyscall_tz(void)
130 {
131 struct vdso_time_data *vdata = vdso_k_time_data;
132
133 vdata->tz_minuteswest = sys_tz.tz_minuteswest;
134 vdata->tz_dsttime = sys_tz.tz_dsttime;
135
136 __arch_sync_vdso_time_data(vdata);
137 }
138
139 /**
140 * vdso_update_begin - Start of a VDSO update section
141 *
142 * Allows architecture code to safely update the architecture specific VDSO
143 * data. Disables interrupts, acquires timekeeper lock to serialize against
144 * concurrent updates from timekeeping and invalidates the VDSO data
145 * sequence counter to prevent concurrent readers from accessing
146 * inconsistent data.
147 *
148 * Returns: Saved interrupt flags which need to be handed in to
149 * vdso_update_end().
150 */
vdso_update_begin(void)151 unsigned long vdso_update_begin(void)
152 {
153 struct vdso_time_data *vdata = vdso_k_time_data;
154 unsigned long flags = timekeeper_lock_irqsave();
155
156 vdso_write_begin(vdata);
157 return flags;
158 }
159
160 /**
161 * vdso_update_end - End of a VDSO update section
162 * @flags: Interrupt flags as returned from vdso_update_begin()
163 *
164 * Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data
165 * synchronization if the architecture requires it, drops timekeeper lock
166 * and restores interrupt flags.
167 */
vdso_update_end(unsigned long flags)168 void vdso_update_end(unsigned long flags)
169 {
170 struct vdso_time_data *vdata = vdso_k_time_data;
171
172 vdso_write_end(vdata);
173 __arch_sync_vdso_time_data(vdata);
174 timekeeper_unlock_irqrestore(flags);
175 }
176