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(vd: 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(dividend: nsec, NSEC_PER_SEC, remainder: &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(vd: 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(vd: 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(vd: vdata); |
168 | __arch_sync_vdso_data(vdata); |
169 | raw_spin_unlock_irqrestore(&timekeeper_lock, flags); |
170 | } |
171 | |