Merge tag 'block-5.15-2021-09-05' of git://git.kernel.dk/linux-block
[linux-2.6-microblaze.git] / kernel / time / vsyscall.c
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         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
72 void 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
123 void 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  */
145 unsigned 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  */
163 void 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 }