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
18 static 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 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
26 vdata[CS_HRES_COARSE].max_cycles = tk->tkr_mono.clock->max_cycles;
27 #endif
28 vdata[CS_HRES_COARSE].mask = tk->tkr_mono.mask;
29 vdata[CS_HRES_COARSE].mult = tk->tkr_mono.mult;
30 vdata[CS_HRES_COARSE].shift = tk->tkr_mono.shift;
31 vdata[CS_RAW].cycle_last = tk->tkr_raw.cycle_last;
32 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
33 vdata[CS_RAW].max_cycles = tk->tkr_raw.clock->max_cycles;
34 #endif
35 vdata[CS_RAW].mask = tk->tkr_raw.mask;
36 vdata[CS_RAW].mult = tk->tkr_raw.mult;
37 vdata[CS_RAW].shift = tk->tkr_raw.shift;
38
39 /* CLOCK_MONOTONIC */
40 vdso_ts = &vdata[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 = &vdata[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 = &vdata[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 = &vdata[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
78 void update_vsyscall(struct timekeeper *tk)
79 {
80 struct vdso_data *vdata = __arch_get_k_vdso_data();
81 struct vdso_timestamp *vdso_ts;
82 s32 clock_mode;
83 u64 nsec;
84
85 /* copy vsyscall data */
86 vdso_write_begin(vdata);
87
88 clock_mode = tk->tkr_mono.clock->vdso_clock_mode;
89 vdata[CS_HRES_COARSE].clock_mode = clock_mode;
90 vdata[CS_RAW].clock_mode = clock_mode;
91
92 /* CLOCK_REALTIME also required for time() */
93 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
94 vdso_ts->sec = tk->xtime_sec;
95 vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
96
97 /* CLOCK_REALTIME_COARSE */
98 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
99 vdso_ts->sec = tk->xtime_sec;
100 vdso_ts->nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
101
102 /* CLOCK_MONOTONIC_COARSE */
103 vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE];
104 vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
105 nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
106 nsec = nsec + tk->wall_to_monotonic.tv_nsec;
107 vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
108
109 /*
110 * Read without the seqlock held by clock_getres().
111 * Note: No need to have a second copy.
112 */
113 WRITE_ONCE(vdata[CS_HRES_COARSE].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_data(vdata, tk);
121
122 __arch_update_vsyscall(vdata, tk);
123
124 vdso_write_end(vdata);
125
126 __arch_sync_vdso_data(vdata);
127 }
128
129 void update_vsyscall_tz(void)
130 {
131 struct vdso_data *vdata = __arch_get_k_vdso_data();
132
133 vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest;
134 vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime;
135
136 __arch_sync_vdso_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 */
151 unsigned long vdso_update_begin(void)
152 {
153 struct vdso_data *vdata = __arch_get_k_vdso_data();
154 unsigned long flags;
155
156 raw_spin_lock_irqsave(&timekeeper_lock, flags);
157 vdso_write_begin(vdata);
158 return flags;
159 }
160
161 /**
162 * vdso_update_end - End of a VDSO update section
163 * @flags: Interrupt flags as returned from vdso_update_begin()
164 *
165 * Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data
166 * synchronization if the architecture requires it, drops timekeeper lock
167 * and restores interrupt flags.
168 */
169 void vdso_update_end(unsigned long flags)
170 {
171 struct vdso_data *vdata = __arch_get_k_vdso_data();
172
173 vdso_write_end(vdata);
174 __arch_sync_vdso_data(vdata);
175 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
176 }
177
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