Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Kernel timekeeping code and accessor functions. Based on code from
4 : * timer.c, moved in commit 8524070b7982.
5 : */
6 : #include <linux/timekeeper_internal.h>
7 : #include <linux/module.h>
8 : #include <linux/interrupt.h>
9 : #include <linux/percpu.h>
10 : #include <linux/init.h>
11 : #include <linux/mm.h>
12 : #include <linux/nmi.h>
13 : #include <linux/sched.h>
14 : #include <linux/sched/loadavg.h>
15 : #include <linux/sched/clock.h>
16 : #include <linux/syscore_ops.h>
17 : #include <linux/clocksource.h>
18 : #include <linux/jiffies.h>
19 : #include <linux/time.h>
20 : #include <linux/timex.h>
21 : #include <linux/tick.h>
22 : #include <linux/stop_machine.h>
23 : #include <linux/pvclock_gtod.h>
24 : #include <linux/compiler.h>
25 : #include <linux/audit.h>
26 : #include <linux/random.h>
27 :
28 : #include "tick-internal.h"
29 : #include "ntp_internal.h"
30 : #include "timekeeping_internal.h"
31 :
32 : #define TK_CLEAR_NTP (1 << 0)
33 : #define TK_MIRROR (1 << 1)
34 : #define TK_CLOCK_WAS_SET (1 << 2)
35 :
36 : enum timekeeping_adv_mode {
37 : /* Update timekeeper when a tick has passed */
38 : TK_ADV_TICK,
39 :
40 : /* Update timekeeper on a direct frequency change */
41 : TK_ADV_FREQ
42 : };
43 :
44 : DEFINE_RAW_SPINLOCK(timekeeper_lock);
45 :
46 : /*
47 : * The most important data for readout fits into a single 64 byte
48 : * cache line.
49 : */
50 : static struct {
51 : seqcount_raw_spinlock_t seq;
52 : struct timekeeper timekeeper;
53 : } tk_core ____cacheline_aligned = {
54 : .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock),
55 : };
56 :
57 : static struct timekeeper shadow_timekeeper;
58 :
59 : /* flag for if timekeeping is suspended */
60 : int __read_mostly timekeeping_suspended;
61 :
62 : /**
63 : * struct tk_fast - NMI safe timekeeper
64 : * @seq: Sequence counter for protecting updates. The lowest bit
65 : * is the index for the tk_read_base array
66 : * @base: tk_read_base array. Access is indexed by the lowest bit of
67 : * @seq.
68 : *
69 : * See @update_fast_timekeeper() below.
70 : */
71 : struct tk_fast {
72 : seqcount_latch_t seq;
73 : struct tk_read_base base[2];
74 : };
75 :
76 : /* Suspend-time cycles value for halted fast timekeeper. */
77 : static u64 cycles_at_suspend;
78 :
79 0 : static u64 dummy_clock_read(struct clocksource *cs)
80 : {
81 0 : if (timekeeping_suspended)
82 0 : return cycles_at_suspend;
83 0 : return local_clock();
84 : }
85 :
86 : static struct clocksource dummy_clock = {
87 : .read = dummy_clock_read,
88 : };
89 :
90 : /*
91 : * Boot time initialization which allows local_clock() to be utilized
92 : * during early boot when clocksources are not available. local_clock()
93 : * returns nanoseconds already so no conversion is required, hence mult=1
94 : * and shift=0. When the first proper clocksource is installed then
95 : * the fast time keepers are updated with the correct values.
96 : */
97 : #define FAST_TK_INIT \
98 : { \
99 : .clock = &dummy_clock, \
100 : .mask = CLOCKSOURCE_MASK(64), \
101 : .mult = 1, \
102 : .shift = 0, \
103 : }
104 :
105 : static struct tk_fast tk_fast_mono ____cacheline_aligned = {
106 : .seq = SEQCNT_LATCH_ZERO(tk_fast_mono.seq),
107 : .base[0] = FAST_TK_INIT,
108 : .base[1] = FAST_TK_INIT,
109 : };
110 :
111 : static struct tk_fast tk_fast_raw ____cacheline_aligned = {
112 : .seq = SEQCNT_LATCH_ZERO(tk_fast_raw.seq),
113 : .base[0] = FAST_TK_INIT,
114 : .base[1] = FAST_TK_INIT,
115 : };
116 :
117 : static inline void tk_normalize_xtime(struct timekeeper *tk)
118 : {
119 1 : while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
120 0 : tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
121 0 : tk->xtime_sec++;
122 : }
123 1 : while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
124 0 : tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
125 0 : tk->raw_sec++;
126 : }
127 : }
128 :
129 : static inline struct timespec64 tk_xtime(const struct timekeeper *tk)
130 : {
131 : struct timespec64 ts;
132 :
133 54 : ts.tv_sec = tk->xtime_sec;
134 54 : ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
135 : return ts;
136 : }
137 :
138 : static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
139 : {
140 1 : tk->xtime_sec = ts->tv_sec;
141 1 : tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
142 : }
143 :
144 0 : static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
145 : {
146 0 : tk->xtime_sec += ts->tv_sec;
147 0 : tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
148 0 : tk_normalize_xtime(tk);
149 0 : }
150 :
151 1 : static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
152 : {
153 : struct timespec64 tmp;
154 :
155 : /*
156 : * Verify consistency of: offset_real = -wall_to_monotonic
157 : * before modifying anything
158 : */
159 1 : set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
160 1 : -tk->wall_to_monotonic.tv_nsec);
161 2 : WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
162 1 : tk->wall_to_monotonic = wtm;
163 1 : set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
164 1 : tk->offs_real = timespec64_to_ktime(tmp);
165 2 : tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
166 1 : }
167 :
168 : static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
169 : {
170 0 : tk->offs_boot = ktime_add(tk->offs_boot, delta);
171 : /*
172 : * Timespec representation for VDSO update to avoid 64bit division
173 : * on every update.
174 : */
175 0 : tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot);
176 : }
177 :
178 : /*
179 : * tk_clock_read - atomic clocksource read() helper
180 : *
181 : * This helper is necessary to use in the read paths because, while the
182 : * seqcount ensures we don't return a bad value while structures are updated,
183 : * it doesn't protect from potential crashes. There is the possibility that
184 : * the tkr's clocksource may change between the read reference, and the
185 : * clock reference passed to the read function. This can cause crashes if
186 : * the wrong clocksource is passed to the wrong read function.
187 : * This isn't necessary to use when holding the timekeeper_lock or doing
188 : * a read of the fast-timekeeper tkrs (which is protected by its own locking
189 : * and update logic).
190 : */
191 : static inline u64 tk_clock_read(const struct tk_read_base *tkr)
192 : {
193 6213 : struct clocksource *clock = READ_ONCE(tkr->clock);
194 :
195 6213 : return clock->read(clock);
196 : }
197 :
198 : #ifdef CONFIG_DEBUG_TIMEKEEPING
199 : #define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
200 :
201 : static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
202 : {
203 :
204 : u64 max_cycles = tk->tkr_mono.clock->max_cycles;
205 : const char *name = tk->tkr_mono.clock->name;
206 :
207 : if (offset > max_cycles) {
208 : printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
209 : offset, name, max_cycles);
210 : printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
211 : } else {
212 : if (offset > (max_cycles >> 1)) {
213 : printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
214 : offset, name, max_cycles >> 1);
215 : printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
216 : }
217 : }
218 :
219 : if (tk->underflow_seen) {
220 : if (jiffies - tk->last_warning > WARNING_FREQ) {
221 : printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
222 : printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
223 : printk_deferred(" Your kernel is probably still fine.\n");
224 : tk->last_warning = jiffies;
225 : }
226 : tk->underflow_seen = 0;
227 : }
228 :
229 : if (tk->overflow_seen) {
230 : if (jiffies - tk->last_warning > WARNING_FREQ) {
231 : printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
232 : printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
233 : printk_deferred(" Your kernel is probably still fine.\n");
234 : tk->last_warning = jiffies;
235 : }
236 : tk->overflow_seen = 0;
237 : }
238 : }
239 :
240 : static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
241 : {
242 : struct timekeeper *tk = &tk_core.timekeeper;
243 : u64 now, last, mask, max, delta;
244 : unsigned int seq;
245 :
246 : /*
247 : * Since we're called holding a seqcount, the data may shift
248 : * under us while we're doing the calculation. This can cause
249 : * false positives, since we'd note a problem but throw the
250 : * results away. So nest another seqcount here to atomically
251 : * grab the points we are checking with.
252 : */
253 : do {
254 : seq = read_seqcount_begin(&tk_core.seq);
255 : now = tk_clock_read(tkr);
256 : last = tkr->cycle_last;
257 : mask = tkr->mask;
258 : max = tkr->clock->max_cycles;
259 : } while (read_seqcount_retry(&tk_core.seq, seq));
260 :
261 : delta = clocksource_delta(now, last, mask);
262 :
263 : /*
264 : * Try to catch underflows by checking if we are seeing small
265 : * mask-relative negative values.
266 : */
267 : if (unlikely((~delta & mask) < (mask >> 3))) {
268 : tk->underflow_seen = 1;
269 : delta = 0;
270 : }
271 :
272 : /* Cap delta value to the max_cycles values to avoid mult overflows */
273 : if (unlikely(delta > max)) {
274 : tk->overflow_seen = 1;
275 : delta = tkr->clock->max_cycles;
276 : }
277 :
278 : return delta;
279 : }
280 : #else
281 : static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
282 : {
283 : }
284 : static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
285 : {
286 : u64 cycle_now, delta;
287 :
288 : /* read clocksource */
289 3459 : cycle_now = tk_clock_read(tkr);
290 :
291 : /* calculate the delta since the last update_wall_time */
292 6918 : delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
293 :
294 : return delta;
295 : }
296 : #endif
297 :
298 : /**
299 : * tk_setup_internals - Set up internals to use clocksource clock.
300 : *
301 : * @tk: The target timekeeper to setup.
302 : * @clock: Pointer to clocksource.
303 : *
304 : * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
305 : * pair and interval request.
306 : *
307 : * Unless you're the timekeeping code, you should not be using this!
308 : */
309 2 : static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
310 : {
311 : u64 interval;
312 : u64 tmp, ntpinterval;
313 : struct clocksource *old_clock;
314 :
315 2 : ++tk->cs_was_changed_seq;
316 2 : old_clock = tk->tkr_mono.clock;
317 2 : tk->tkr_mono.clock = clock;
318 2 : tk->tkr_mono.mask = clock->mask;
319 4 : tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
320 :
321 2 : tk->tkr_raw.clock = clock;
322 2 : tk->tkr_raw.mask = clock->mask;
323 2 : tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
324 :
325 : /* Do the ns -> cycle conversion first, using original mult */
326 2 : tmp = NTP_INTERVAL_LENGTH;
327 2 : tmp <<= clock->shift;
328 2 : ntpinterval = tmp;
329 2 : tmp += clock->mult/2;
330 2 : do_div(tmp, clock->mult);
331 2 : if (tmp == 0)
332 0 : tmp = 1;
333 :
334 2 : interval = (u64) tmp;
335 2 : tk->cycle_interval = interval;
336 :
337 : /* Go back from cycles -> shifted ns */
338 2 : tk->xtime_interval = interval * clock->mult;
339 2 : tk->xtime_remainder = ntpinterval - tk->xtime_interval;
340 2 : tk->raw_interval = interval * clock->mult;
341 :
342 : /* if changing clocks, convert xtime_nsec shift units */
343 2 : if (old_clock) {
344 1 : int shift_change = clock->shift - old_clock->shift;
345 1 : if (shift_change < 0) {
346 0 : tk->tkr_mono.xtime_nsec >>= -shift_change;
347 0 : tk->tkr_raw.xtime_nsec >>= -shift_change;
348 : } else {
349 1 : tk->tkr_mono.xtime_nsec <<= shift_change;
350 1 : tk->tkr_raw.xtime_nsec <<= shift_change;
351 : }
352 : }
353 :
354 2 : tk->tkr_mono.shift = clock->shift;
355 2 : tk->tkr_raw.shift = clock->shift;
356 :
357 2 : tk->ntp_error = 0;
358 2 : tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
359 2 : tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
360 :
361 : /*
362 : * The timekeeper keeps its own mult values for the currently
363 : * active clocksource. These value will be adjusted via NTP
364 : * to counteract clock drifting.
365 : */
366 2 : tk->tkr_mono.mult = clock->mult;
367 2 : tk->tkr_raw.mult = clock->mult;
368 2 : tk->ntp_err_mult = 0;
369 2 : tk->skip_second_overflow = 0;
370 2 : }
371 :
372 : /* Timekeeper helper functions. */
373 :
374 : static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta)
375 : {
376 : u64 nsec;
377 :
378 3459 : nsec = delta * tkr->mult + tkr->xtime_nsec;
379 3459 : nsec >>= tkr->shift;
380 :
381 : return nsec;
382 : }
383 :
384 : static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
385 : {
386 : u64 delta;
387 :
388 3459 : delta = timekeeping_get_delta(tkr);
389 6918 : return timekeeping_delta_to_ns(tkr, delta);
390 : }
391 :
392 : static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
393 : {
394 : u64 delta;
395 :
396 : /* calculate the delta since the last update_wall_time */
397 0 : delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
398 0 : return timekeeping_delta_to_ns(tkr, delta);
399 : }
400 :
401 : /**
402 : * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
403 : * @tkr: Timekeeping readout base from which we take the update
404 : * @tkf: Pointer to NMI safe timekeeper
405 : *
406 : * We want to use this from any context including NMI and tracing /
407 : * instrumenting the timekeeping code itself.
408 : *
409 : * Employ the latch technique; see @raw_write_seqcount_latch.
410 : *
411 : * So if a NMI hits the update of base[0] then it will use base[1]
412 : * which is still consistent. In the worst case this can result is a
413 : * slightly wrong timestamp (a few nanoseconds). See
414 : * @ktime_get_mono_fast_ns.
415 : */
416 5498 : static void update_fast_timekeeper(const struct tk_read_base *tkr,
417 : struct tk_fast *tkf)
418 : {
419 5498 : struct tk_read_base *base = tkf->base;
420 :
421 : /* Force readers off to base[1] */
422 10996 : raw_write_seqcount_latch(&tkf->seq);
423 :
424 : /* Update base[0] */
425 5498 : memcpy(base, tkr, sizeof(*base));
426 :
427 : /* Force readers back to base[0] */
428 10996 : raw_write_seqcount_latch(&tkf->seq);
429 :
430 : /* Update base[1] */
431 5498 : memcpy(base + 1, base, sizeof(*base));
432 5498 : }
433 :
434 : static __always_inline u64 fast_tk_get_delta_ns(struct tk_read_base *tkr)
435 : {
436 0 : u64 delta, cycles = tk_clock_read(tkr);
437 :
438 0 : delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
439 0 : return timekeeping_delta_to_ns(tkr, delta);
440 : }
441 :
442 : static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
443 : {
444 : struct tk_read_base *tkr;
445 : unsigned int seq;
446 : u64 now;
447 :
448 : do {
449 0 : seq = raw_read_seqcount_latch(&tkf->seq);
450 0 : tkr = tkf->base + (seq & 0x01);
451 0 : now = ktime_to_ns(tkr->base);
452 0 : now += fast_tk_get_delta_ns(tkr);
453 0 : } while (read_seqcount_latch_retry(&tkf->seq, seq));
454 :
455 : return now;
456 : }
457 :
458 : /**
459 : * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
460 : *
461 : * This timestamp is not guaranteed to be monotonic across an update.
462 : * The timestamp is calculated by:
463 : *
464 : * now = base_mono + clock_delta * slope
465 : *
466 : * So if the update lowers the slope, readers who are forced to the
467 : * not yet updated second array are still using the old steeper slope.
468 : *
469 : * tmono
470 : * ^
471 : * | o n
472 : * | o n
473 : * | u
474 : * | o
475 : * |o
476 : * |12345678---> reader order
477 : *
478 : * o = old slope
479 : * u = update
480 : * n = new slope
481 : *
482 : * So reader 6 will observe time going backwards versus reader 5.
483 : *
484 : * While other CPUs are likely to be able to observe that, the only way
485 : * for a CPU local observation is when an NMI hits in the middle of
486 : * the update. Timestamps taken from that NMI context might be ahead
487 : * of the following timestamps. Callers need to be aware of that and
488 : * deal with it.
489 : */
490 0 : u64 notrace ktime_get_mono_fast_ns(void)
491 : {
492 0 : return __ktime_get_fast_ns(&tk_fast_mono);
493 : }
494 : EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
495 :
496 : /**
497 : * ktime_get_raw_fast_ns - Fast NMI safe access to clock monotonic raw
498 : *
499 : * Contrary to ktime_get_mono_fast_ns() this is always correct because the
500 : * conversion factor is not affected by NTP/PTP correction.
501 : */
502 0 : u64 notrace ktime_get_raw_fast_ns(void)
503 : {
504 0 : return __ktime_get_fast_ns(&tk_fast_raw);
505 : }
506 : EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
507 :
508 : /**
509 : * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
510 : *
511 : * To keep it NMI safe since we're accessing from tracing, we're not using a
512 : * separate timekeeper with updates to monotonic clock and boot offset
513 : * protected with seqcounts. This has the following minor side effects:
514 : *
515 : * (1) Its possible that a timestamp be taken after the boot offset is updated
516 : * but before the timekeeper is updated. If this happens, the new boot offset
517 : * is added to the old timekeeping making the clock appear to update slightly
518 : * earlier:
519 : * CPU 0 CPU 1
520 : * timekeeping_inject_sleeptime64()
521 : * __timekeeping_inject_sleeptime(tk, delta);
522 : * timestamp();
523 : * timekeeping_update(tk, TK_CLEAR_NTP...);
524 : *
525 : * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
526 : * partially updated. Since the tk->offs_boot update is a rare event, this
527 : * should be a rare occurrence which postprocessing should be able to handle.
528 : *
529 : * The caveats vs. timestamp ordering as documented for ktime_get_fast_ns()
530 : * apply as well.
531 : */
532 0 : u64 notrace ktime_get_boot_fast_ns(void)
533 : {
534 0 : struct timekeeper *tk = &tk_core.timekeeper;
535 :
536 0 : return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_boot)));
537 : }
538 : EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
539 :
540 : /**
541 : * ktime_get_tai_fast_ns - NMI safe and fast access to tai clock.
542 : *
543 : * The same limitations as described for ktime_get_boot_fast_ns() apply. The
544 : * mono time and the TAI offset are not read atomically which may yield wrong
545 : * readouts. However, an update of the TAI offset is an rare event e.g., caused
546 : * by settime or adjtimex with an offset. The user of this function has to deal
547 : * with the possibility of wrong timestamps in post processing.
548 : */
549 0 : u64 notrace ktime_get_tai_fast_ns(void)
550 : {
551 0 : struct timekeeper *tk = &tk_core.timekeeper;
552 :
553 0 : return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_tai)));
554 : }
555 : EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns);
556 :
557 : static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono)
558 : {
559 : struct tk_read_base *tkr;
560 : u64 basem, baser, delta;
561 : unsigned int seq;
562 :
563 : do {
564 0 : seq = raw_read_seqcount_latch(&tkf->seq);
565 0 : tkr = tkf->base + (seq & 0x01);
566 0 : basem = ktime_to_ns(tkr->base);
567 0 : baser = ktime_to_ns(tkr->base_real);
568 0 : delta = fast_tk_get_delta_ns(tkr);
569 0 : } while (read_seqcount_latch_retry(&tkf->seq, seq));
570 :
571 0 : if (mono)
572 0 : *mono = basem + delta;
573 0 : return baser + delta;
574 : }
575 :
576 : /**
577 : * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
578 : *
579 : * See ktime_get_fast_ns() for documentation of the time stamp ordering.
580 : */
581 0 : u64 ktime_get_real_fast_ns(void)
582 : {
583 0 : return __ktime_get_real_fast(&tk_fast_mono, NULL);
584 : }
585 : EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
586 :
587 : /**
588 : * ktime_get_fast_timestamps: - NMI safe timestamps
589 : * @snapshot: Pointer to timestamp storage
590 : *
591 : * Stores clock monotonic, boottime and realtime timestamps.
592 : *
593 : * Boot time is a racy access on 32bit systems if the sleep time injection
594 : * happens late during resume and not in timekeeping_resume(). That could
595 : * be avoided by expanding struct tk_read_base with boot offset for 32bit
596 : * and adding more overhead to the update. As this is a hard to observe
597 : * once per resume event which can be filtered with reasonable effort using
598 : * the accurate mono/real timestamps, it's probably not worth the trouble.
599 : *
600 : * Aside of that it might be possible on 32 and 64 bit to observe the
601 : * following when the sleep time injection happens late:
602 : *
603 : * CPU 0 CPU 1
604 : * timekeeping_resume()
605 : * ktime_get_fast_timestamps()
606 : * mono, real = __ktime_get_real_fast()
607 : * inject_sleep_time()
608 : * update boot offset
609 : * boot = mono + bootoffset;
610 : *
611 : * That means that boot time already has the sleep time adjustment, but
612 : * real time does not. On the next readout both are in sync again.
613 : *
614 : * Preventing this for 64bit is not really feasible without destroying the
615 : * careful cache layout of the timekeeper because the sequence count and
616 : * struct tk_read_base would then need two cache lines instead of one.
617 : *
618 : * Access to the time keeper clock source is disabled across the innermost
619 : * steps of suspend/resume. The accessors still work, but the timestamps
620 : * are frozen until time keeping is resumed which happens very early.
621 : *
622 : * For regular suspend/resume there is no observable difference vs. sched
623 : * clock, but it might affect some of the nasty low level debug printks.
624 : *
625 : * OTOH, access to sched clock is not guaranteed across suspend/resume on
626 : * all systems either so it depends on the hardware in use.
627 : *
628 : * If that turns out to be a real problem then this could be mitigated by
629 : * using sched clock in a similar way as during early boot. But it's not as
630 : * trivial as on early boot because it needs some careful protection
631 : * against the clock monotonic timestamp jumping backwards on resume.
632 : */
633 0 : void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot)
634 : {
635 0 : struct timekeeper *tk = &tk_core.timekeeper;
636 :
637 0 : snapshot->real = __ktime_get_real_fast(&tk_fast_mono, &snapshot->mono);
638 0 : snapshot->boot = snapshot->mono + ktime_to_ns(data_race(tk->offs_boot));
639 0 : }
640 :
641 : /**
642 : * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
643 : * @tk: Timekeeper to snapshot.
644 : *
645 : * It generally is unsafe to access the clocksource after timekeeping has been
646 : * suspended, so take a snapshot of the readout base of @tk and use it as the
647 : * fast timekeeper's readout base while suspended. It will return the same
648 : * number of cycles every time until timekeeping is resumed at which time the
649 : * proper readout base for the fast timekeeper will be restored automatically.
650 : */
651 0 : static void halt_fast_timekeeper(const struct timekeeper *tk)
652 : {
653 : static struct tk_read_base tkr_dummy;
654 0 : const struct tk_read_base *tkr = &tk->tkr_mono;
655 :
656 0 : memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
657 0 : cycles_at_suspend = tk_clock_read(tkr);
658 0 : tkr_dummy.clock = &dummy_clock;
659 0 : tkr_dummy.base_real = tkr->base + tk->offs_real;
660 0 : update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
661 :
662 0 : tkr = &tk->tkr_raw;
663 0 : memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
664 0 : tkr_dummy.clock = &dummy_clock;
665 0 : update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
666 0 : }
667 :
668 : static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
669 :
670 : static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
671 : {
672 2749 : raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
673 : }
674 :
675 : /**
676 : * pvclock_gtod_register_notifier - register a pvclock timedata update listener
677 : * @nb: Pointer to the notifier block to register
678 : */
679 0 : int pvclock_gtod_register_notifier(struct notifier_block *nb)
680 : {
681 0 : struct timekeeper *tk = &tk_core.timekeeper;
682 : unsigned long flags;
683 : int ret;
684 :
685 0 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
686 0 : ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
687 0 : update_pvclock_gtod(tk, true);
688 0 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
689 :
690 0 : return ret;
691 : }
692 : EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
693 :
694 : /**
695 : * pvclock_gtod_unregister_notifier - unregister a pvclock
696 : * timedata update listener
697 : * @nb: Pointer to the notifier block to unregister
698 : */
699 0 : int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
700 : {
701 : unsigned long flags;
702 : int ret;
703 :
704 0 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
705 0 : ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
706 0 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
707 :
708 0 : return ret;
709 : }
710 : EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
711 :
712 : /*
713 : * tk_update_leap_state - helper to update the next_leap_ktime
714 : */
715 : static inline void tk_update_leap_state(struct timekeeper *tk)
716 : {
717 2749 : tk->next_leap_ktime = ntp_get_next_leap();
718 2749 : if (tk->next_leap_ktime != KTIME_MAX)
719 : /* Convert to monotonic time */
720 0 : tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
721 : }
722 :
723 : /*
724 : * Update the ktime_t based scalar nsec members of the timekeeper
725 : */
726 : static inline void tk_update_ktime_data(struct timekeeper *tk)
727 : {
728 : u64 seconds;
729 : u32 nsec;
730 :
731 : /*
732 : * The xtime based monotonic readout is:
733 : * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
734 : * The ktime based monotonic readout is:
735 : * nsec = base_mono + now();
736 : * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
737 : */
738 2749 : seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
739 2749 : nsec = (u32) tk->wall_to_monotonic.tv_nsec;
740 5498 : tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
741 :
742 : /*
743 : * The sum of the nanoseconds portions of xtime and
744 : * wall_to_monotonic can be greater/equal one second. Take
745 : * this into account before updating tk->ktime_sec.
746 : */
747 2749 : nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
748 2749 : if (nsec >= NSEC_PER_SEC)
749 1805 : seconds++;
750 2749 : tk->ktime_sec = seconds;
751 :
752 : /* Update the monotonic raw base */
753 5498 : tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
754 : }
755 :
756 : /* must hold timekeeper_lock */
757 2749 : static void timekeeping_update(struct timekeeper *tk, unsigned int action)
758 : {
759 2749 : if (action & TK_CLEAR_NTP) {
760 1 : tk->ntp_error = 0;
761 1 : ntp_clear();
762 : }
763 :
764 5498 : tk_update_leap_state(tk);
765 2749 : tk_update_ktime_data(tk);
766 :
767 2749 : update_vsyscall(tk);
768 5498 : update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
769 :
770 2749 : tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
771 2749 : update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
772 2749 : update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
773 :
774 2749 : if (action & TK_CLOCK_WAS_SET)
775 2 : tk->clock_was_set_seq++;
776 : /*
777 : * The mirroring of the data to the shadow-timekeeper needs
778 : * to happen last here to ensure we don't over-write the
779 : * timekeeper structure on the next update with stale data
780 : */
781 2749 : if (action & TK_MIRROR)
782 2 : memcpy(&shadow_timekeeper, &tk_core.timekeeper,
783 : sizeof(tk_core.timekeeper));
784 2749 : }
785 :
786 : /**
787 : * timekeeping_forward_now - update clock to the current time
788 : * @tk: Pointer to the timekeeper to update
789 : *
790 : * Forward the current clock to update its state since the last call to
791 : * update_wall_time(). This is useful before significant clock changes,
792 : * as it avoids having to deal with this time offset explicitly.
793 : */
794 1 : static void timekeeping_forward_now(struct timekeeper *tk)
795 : {
796 : u64 cycle_now, delta;
797 :
798 2 : cycle_now = tk_clock_read(&tk->tkr_mono);
799 2 : delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
800 1 : tk->tkr_mono.cycle_last = cycle_now;
801 1 : tk->tkr_raw.cycle_last = cycle_now;
802 :
803 1 : tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
804 1 : tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
805 :
806 1 : tk_normalize_xtime(tk);
807 1 : }
808 :
809 : /**
810 : * ktime_get_real_ts64 - Returns the time of day in a timespec64.
811 : * @ts: pointer to the timespec to be set
812 : *
813 : * Returns the time of day in a timespec64 (WARN if suspended).
814 : */
815 0 : void ktime_get_real_ts64(struct timespec64 *ts)
816 : {
817 0 : struct timekeeper *tk = &tk_core.timekeeper;
818 : unsigned int seq;
819 : u64 nsecs;
820 :
821 0 : WARN_ON(timekeeping_suspended);
822 :
823 : do {
824 0 : seq = read_seqcount_begin(&tk_core.seq);
825 :
826 0 : ts->tv_sec = tk->xtime_sec;
827 0 : nsecs = timekeeping_get_ns(&tk->tkr_mono);
828 :
829 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
830 :
831 : ts->tv_nsec = 0;
832 0 : timespec64_add_ns(ts, nsecs);
833 0 : }
834 : EXPORT_SYMBOL(ktime_get_real_ts64);
835 :
836 359 : ktime_t ktime_get(void)
837 : {
838 359 : struct timekeeper *tk = &tk_core.timekeeper;
839 : unsigned int seq;
840 : ktime_t base;
841 : u64 nsecs;
842 :
843 359 : WARN_ON(timekeeping_suspended);
844 :
845 : do {
846 359 : seq = read_seqcount_begin(&tk_core.seq);
847 359 : base = tk->tkr_mono.base;
848 718 : nsecs = timekeeping_get_ns(&tk->tkr_mono);
849 :
850 718 : } while (read_seqcount_retry(&tk_core.seq, seq));
851 :
852 359 : return ktime_add_ns(base, nsecs);
853 : }
854 : EXPORT_SYMBOL_GPL(ktime_get);
855 :
856 0 : u32 ktime_get_resolution_ns(void)
857 : {
858 0 : struct timekeeper *tk = &tk_core.timekeeper;
859 : unsigned int seq;
860 : u32 nsecs;
861 :
862 0 : WARN_ON(timekeeping_suspended);
863 :
864 : do {
865 0 : seq = read_seqcount_begin(&tk_core.seq);
866 0 : nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
867 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
868 :
869 0 : return nsecs;
870 : }
871 : EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
872 :
873 : static ktime_t *offsets[TK_OFFS_MAX] = {
874 : [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
875 : [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
876 : [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
877 : };
878 :
879 349 : ktime_t ktime_get_with_offset(enum tk_offsets offs)
880 : {
881 349 : struct timekeeper *tk = &tk_core.timekeeper;
882 : unsigned int seq;
883 349 : ktime_t base, *offset = offsets[offs];
884 : u64 nsecs;
885 :
886 349 : WARN_ON(timekeeping_suspended);
887 :
888 : do {
889 349 : seq = read_seqcount_begin(&tk_core.seq);
890 349 : base = ktime_add(tk->tkr_mono.base, *offset);
891 698 : nsecs = timekeeping_get_ns(&tk->tkr_mono);
892 :
893 698 : } while (read_seqcount_retry(&tk_core.seq, seq));
894 :
895 349 : return ktime_add_ns(base, nsecs);
896 :
897 : }
898 : EXPORT_SYMBOL_GPL(ktime_get_with_offset);
899 :
900 0 : ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
901 : {
902 0 : struct timekeeper *tk = &tk_core.timekeeper;
903 : unsigned int seq;
904 0 : ktime_t base, *offset = offsets[offs];
905 : u64 nsecs;
906 :
907 0 : WARN_ON(timekeeping_suspended);
908 :
909 : do {
910 0 : seq = read_seqcount_begin(&tk_core.seq);
911 0 : base = ktime_add(tk->tkr_mono.base, *offset);
912 0 : nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
913 :
914 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
915 :
916 0 : return ktime_add_ns(base, nsecs);
917 : }
918 : EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
919 :
920 : /**
921 : * ktime_mono_to_any() - convert monotonic time to any other time
922 : * @tmono: time to convert.
923 : * @offs: which offset to use
924 : */
925 0 : ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
926 : {
927 0 : ktime_t *offset = offsets[offs];
928 : unsigned int seq;
929 : ktime_t tconv;
930 :
931 : do {
932 0 : seq = read_seqcount_begin(&tk_core.seq);
933 0 : tconv = ktime_add(tmono, *offset);
934 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
935 :
936 0 : return tconv;
937 : }
938 : EXPORT_SYMBOL_GPL(ktime_mono_to_any);
939 :
940 : /**
941 : * ktime_get_raw - Returns the raw monotonic time in ktime_t format
942 : */
943 0 : ktime_t ktime_get_raw(void)
944 : {
945 0 : struct timekeeper *tk = &tk_core.timekeeper;
946 : unsigned int seq;
947 : ktime_t base;
948 : u64 nsecs;
949 :
950 : do {
951 0 : seq = read_seqcount_begin(&tk_core.seq);
952 0 : base = tk->tkr_raw.base;
953 0 : nsecs = timekeeping_get_ns(&tk->tkr_raw);
954 :
955 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
956 :
957 0 : return ktime_add_ns(base, nsecs);
958 : }
959 : EXPORT_SYMBOL_GPL(ktime_get_raw);
960 :
961 : /**
962 : * ktime_get_ts64 - get the monotonic clock in timespec64 format
963 : * @ts: pointer to timespec variable
964 : *
965 : * The function calculates the monotonic clock from the realtime
966 : * clock and the wall_to_monotonic offset and stores the result
967 : * in normalized timespec64 format in the variable pointed to by @ts.
968 : */
969 0 : void ktime_get_ts64(struct timespec64 *ts)
970 : {
971 0 : struct timekeeper *tk = &tk_core.timekeeper;
972 : struct timespec64 tomono;
973 : unsigned int seq;
974 : u64 nsec;
975 :
976 0 : WARN_ON(timekeeping_suspended);
977 :
978 : do {
979 0 : seq = read_seqcount_begin(&tk_core.seq);
980 0 : ts->tv_sec = tk->xtime_sec;
981 0 : nsec = timekeeping_get_ns(&tk->tkr_mono);
982 0 : tomono = tk->wall_to_monotonic;
983 :
984 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
985 :
986 0 : ts->tv_sec += tomono.tv_sec;
987 : ts->tv_nsec = 0;
988 0 : timespec64_add_ns(ts, nsec + tomono.tv_nsec);
989 0 : }
990 : EXPORT_SYMBOL_GPL(ktime_get_ts64);
991 :
992 : /**
993 : * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
994 : *
995 : * Returns the seconds portion of CLOCK_MONOTONIC with a single non
996 : * serialized read. tk->ktime_sec is of type 'unsigned long' so this
997 : * works on both 32 and 64 bit systems. On 32 bit systems the readout
998 : * covers ~136 years of uptime which should be enough to prevent
999 : * premature wrap arounds.
1000 : */
1001 9 : time64_t ktime_get_seconds(void)
1002 : {
1003 9 : struct timekeeper *tk = &tk_core.timekeeper;
1004 :
1005 9 : WARN_ON(timekeeping_suspended);
1006 9 : return tk->ktime_sec;
1007 : }
1008 : EXPORT_SYMBOL_GPL(ktime_get_seconds);
1009 :
1010 : /**
1011 : * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
1012 : *
1013 : * Returns the wall clock seconds since 1970.
1014 : *
1015 : * For 64bit systems the fast access to tk->xtime_sec is preserved. On
1016 : * 32bit systems the access must be protected with the sequence
1017 : * counter to provide "atomic" access to the 64bit tk->xtime_sec
1018 : * value.
1019 : */
1020 0 : time64_t ktime_get_real_seconds(void)
1021 : {
1022 0 : struct timekeeper *tk = &tk_core.timekeeper;
1023 : time64_t seconds;
1024 : unsigned int seq;
1025 :
1026 : if (IS_ENABLED(CONFIG_64BIT))
1027 0 : return tk->xtime_sec;
1028 :
1029 : do {
1030 : seq = read_seqcount_begin(&tk_core.seq);
1031 : seconds = tk->xtime_sec;
1032 :
1033 : } while (read_seqcount_retry(&tk_core.seq, seq));
1034 :
1035 : return seconds;
1036 : }
1037 : EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
1038 :
1039 : /**
1040 : * __ktime_get_real_seconds - The same as ktime_get_real_seconds
1041 : * but without the sequence counter protect. This internal function
1042 : * is called just when timekeeping lock is already held.
1043 : */
1044 0 : noinstr time64_t __ktime_get_real_seconds(void)
1045 : {
1046 0 : struct timekeeper *tk = &tk_core.timekeeper;
1047 :
1048 0 : return tk->xtime_sec;
1049 : }
1050 :
1051 : /**
1052 : * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
1053 : * @systime_snapshot: pointer to struct receiving the system time snapshot
1054 : */
1055 0 : void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
1056 : {
1057 0 : struct timekeeper *tk = &tk_core.timekeeper;
1058 : unsigned int seq;
1059 : ktime_t base_raw;
1060 : ktime_t base_real;
1061 : u64 nsec_raw;
1062 : u64 nsec_real;
1063 : u64 now;
1064 :
1065 0 : WARN_ON_ONCE(timekeeping_suspended);
1066 :
1067 : do {
1068 0 : seq = read_seqcount_begin(&tk_core.seq);
1069 0 : now = tk_clock_read(&tk->tkr_mono);
1070 0 : systime_snapshot->cs_id = tk->tkr_mono.clock->id;
1071 0 : systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
1072 0 : systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
1073 0 : base_real = ktime_add(tk->tkr_mono.base,
1074 : tk_core.timekeeper.offs_real);
1075 0 : base_raw = tk->tkr_raw.base;
1076 0 : nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
1077 0 : nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
1078 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
1079 :
1080 0 : systime_snapshot->cycles = now;
1081 0 : systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
1082 0 : systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
1083 0 : }
1084 : EXPORT_SYMBOL_GPL(ktime_get_snapshot);
1085 :
1086 : /* Scale base by mult/div checking for overflow */
1087 0 : static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1088 : {
1089 : u64 tmp, rem;
1090 :
1091 0 : tmp = div64_u64_rem(*base, div, &rem);
1092 :
1093 0 : if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1094 0 : ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1095 : return -EOVERFLOW;
1096 0 : tmp *= mult;
1097 :
1098 0 : rem = div64_u64(rem * mult, div);
1099 0 : *base = tmp + rem;
1100 0 : return 0;
1101 : }
1102 :
1103 : /**
1104 : * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1105 : * @history: Snapshot representing start of history
1106 : * @partial_history_cycles: Cycle offset into history (fractional part)
1107 : * @total_history_cycles: Total history length in cycles
1108 : * @discontinuity: True indicates clock was set on history period
1109 : * @ts: Cross timestamp that should be adjusted using
1110 : * partial/total ratio
1111 : *
1112 : * Helper function used by get_device_system_crosststamp() to correct the
1113 : * crosstimestamp corresponding to the start of the current interval to the
1114 : * system counter value (timestamp point) provided by the driver. The
1115 : * total_history_* quantities are the total history starting at the provided
1116 : * reference point and ending at the start of the current interval. The cycle
1117 : * count between the driver timestamp point and the start of the current
1118 : * interval is partial_history_cycles.
1119 : */
1120 0 : static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1121 : u64 partial_history_cycles,
1122 : u64 total_history_cycles,
1123 : bool discontinuity,
1124 : struct system_device_crosststamp *ts)
1125 : {
1126 0 : struct timekeeper *tk = &tk_core.timekeeper;
1127 : u64 corr_raw, corr_real;
1128 : bool interp_forward;
1129 : int ret;
1130 :
1131 0 : if (total_history_cycles == 0 || partial_history_cycles == 0)
1132 : return 0;
1133 :
1134 : /* Interpolate shortest distance from beginning or end of history */
1135 0 : interp_forward = partial_history_cycles > total_history_cycles / 2;
1136 0 : partial_history_cycles = interp_forward ?
1137 0 : total_history_cycles - partial_history_cycles :
1138 : partial_history_cycles;
1139 :
1140 : /*
1141 : * Scale the monotonic raw time delta by:
1142 : * partial_history_cycles / total_history_cycles
1143 : */
1144 0 : corr_raw = (u64)ktime_to_ns(
1145 0 : ktime_sub(ts->sys_monoraw, history->raw));
1146 0 : ret = scale64_check_overflow(partial_history_cycles,
1147 : total_history_cycles, &corr_raw);
1148 0 : if (ret)
1149 : return ret;
1150 :
1151 : /*
1152 : * If there is a discontinuity in the history, scale monotonic raw
1153 : * correction by:
1154 : * mult(real)/mult(raw) yielding the realtime correction
1155 : * Otherwise, calculate the realtime correction similar to monotonic
1156 : * raw calculation
1157 : */
1158 0 : if (discontinuity) {
1159 0 : corr_real = mul_u64_u32_div
1160 : (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1161 : } else {
1162 0 : corr_real = (u64)ktime_to_ns(
1163 0 : ktime_sub(ts->sys_realtime, history->real));
1164 0 : ret = scale64_check_overflow(partial_history_cycles,
1165 : total_history_cycles, &corr_real);
1166 0 : if (ret)
1167 : return ret;
1168 : }
1169 :
1170 : /* Fixup monotonic raw and real time time values */
1171 0 : if (interp_forward) {
1172 0 : ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1173 0 : ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1174 : } else {
1175 0 : ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1176 0 : ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1177 : }
1178 :
1179 : return 0;
1180 : }
1181 :
1182 : /*
1183 : * cycle_between - true if test occurs chronologically between before and after
1184 : */
1185 : static bool cycle_between(u64 before, u64 test, u64 after)
1186 : {
1187 0 : if (test > before && test < after)
1188 : return true;
1189 0 : if (test < before && before > after)
1190 : return true;
1191 : return false;
1192 : }
1193 :
1194 : /**
1195 : * get_device_system_crosststamp - Synchronously capture system/device timestamp
1196 : * @get_time_fn: Callback to get simultaneous device time and
1197 : * system counter from the device driver
1198 : * @ctx: Context passed to get_time_fn()
1199 : * @history_begin: Historical reference point used to interpolate system
1200 : * time when counter provided by the driver is before the current interval
1201 : * @xtstamp: Receives simultaneously captured system and device time
1202 : *
1203 : * Reads a timestamp from a device and correlates it to system time
1204 : */
1205 0 : int get_device_system_crosststamp(int (*get_time_fn)
1206 : (ktime_t *device_time,
1207 : struct system_counterval_t *sys_counterval,
1208 : void *ctx),
1209 : void *ctx,
1210 : struct system_time_snapshot *history_begin,
1211 : struct system_device_crosststamp *xtstamp)
1212 : {
1213 : struct system_counterval_t system_counterval;
1214 0 : struct timekeeper *tk = &tk_core.timekeeper;
1215 : u64 cycles, now, interval_start;
1216 0 : unsigned int clock_was_set_seq = 0;
1217 : ktime_t base_real, base_raw;
1218 : u64 nsec_real, nsec_raw;
1219 : u8 cs_was_changed_seq;
1220 : unsigned int seq;
1221 : bool do_interp;
1222 : int ret;
1223 :
1224 : do {
1225 0 : seq = read_seqcount_begin(&tk_core.seq);
1226 : /*
1227 : * Try to synchronously capture device time and a system
1228 : * counter value calling back into the device driver
1229 : */
1230 0 : ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1231 0 : if (ret)
1232 : return ret;
1233 :
1234 : /*
1235 : * Verify that the clocksource associated with the captured
1236 : * system counter value is the same as the currently installed
1237 : * timekeeper clocksource
1238 : */
1239 0 : if (tk->tkr_mono.clock != system_counterval.cs)
1240 : return -ENODEV;
1241 0 : cycles = system_counterval.cycles;
1242 :
1243 : /*
1244 : * Check whether the system counter value provided by the
1245 : * device driver is on the current timekeeping interval.
1246 : */
1247 0 : now = tk_clock_read(&tk->tkr_mono);
1248 0 : interval_start = tk->tkr_mono.cycle_last;
1249 0 : if (!cycle_between(interval_start, cycles, now)) {
1250 0 : clock_was_set_seq = tk->clock_was_set_seq;
1251 0 : cs_was_changed_seq = tk->cs_was_changed_seq;
1252 0 : cycles = interval_start;
1253 0 : do_interp = true;
1254 : } else {
1255 : do_interp = false;
1256 : }
1257 :
1258 0 : base_real = ktime_add(tk->tkr_mono.base,
1259 : tk_core.timekeeper.offs_real);
1260 0 : base_raw = tk->tkr_raw.base;
1261 :
1262 0 : nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1263 : system_counterval.cycles);
1264 0 : nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1265 : system_counterval.cycles);
1266 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
1267 :
1268 0 : xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1269 0 : xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1270 :
1271 : /*
1272 : * Interpolate if necessary, adjusting back from the start of the
1273 : * current interval
1274 : */
1275 0 : if (do_interp) {
1276 : u64 partial_history_cycles, total_history_cycles;
1277 : bool discontinuity;
1278 :
1279 : /*
1280 : * Check that the counter value occurs after the provided
1281 : * history reference and that the history doesn't cross a
1282 : * clocksource change
1283 : */
1284 0 : if (!history_begin ||
1285 0 : !cycle_between(history_begin->cycles,
1286 0 : system_counterval.cycles, cycles) ||
1287 0 : history_begin->cs_was_changed_seq != cs_was_changed_seq)
1288 : return -EINVAL;
1289 0 : partial_history_cycles = cycles - system_counterval.cycles;
1290 0 : total_history_cycles = cycles - history_begin->cycles;
1291 0 : discontinuity =
1292 0 : history_begin->clock_was_set_seq != clock_was_set_seq;
1293 :
1294 0 : ret = adjust_historical_crosststamp(history_begin,
1295 : partial_history_cycles,
1296 : total_history_cycles,
1297 : discontinuity, xtstamp);
1298 0 : if (ret)
1299 : return ret;
1300 : }
1301 :
1302 : return 0;
1303 : }
1304 : EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1305 :
1306 : /**
1307 : * do_settimeofday64 - Sets the time of day.
1308 : * @ts: pointer to the timespec64 variable containing the new time
1309 : *
1310 : * Sets the time of day to the new time and update NTP and notify hrtimers
1311 : */
1312 0 : int do_settimeofday64(const struct timespec64 *ts)
1313 : {
1314 0 : struct timekeeper *tk = &tk_core.timekeeper;
1315 : struct timespec64 ts_delta, xt;
1316 : unsigned long flags;
1317 0 : int ret = 0;
1318 :
1319 0 : if (!timespec64_valid_settod(ts))
1320 : return -EINVAL;
1321 :
1322 0 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
1323 0 : write_seqcount_begin(&tk_core.seq);
1324 :
1325 0 : timekeeping_forward_now(tk);
1326 :
1327 0 : xt = tk_xtime(tk);
1328 0 : ts_delta = timespec64_sub(*ts, xt);
1329 :
1330 0 : if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1331 : ret = -EINVAL;
1332 : goto out;
1333 : }
1334 :
1335 0 : tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1336 :
1337 : tk_set_xtime(tk, ts);
1338 : out:
1339 0 : timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1340 :
1341 0 : write_seqcount_end(&tk_core.seq);
1342 0 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1343 :
1344 : /* Signal hrtimers about time change */
1345 0 : clock_was_set(CLOCK_SET_WALL);
1346 :
1347 0 : if (!ret) {
1348 0 : audit_tk_injoffset(ts_delta);
1349 0 : add_device_randomness(ts, sizeof(*ts));
1350 : }
1351 :
1352 : return ret;
1353 : }
1354 : EXPORT_SYMBOL(do_settimeofday64);
1355 :
1356 : /**
1357 : * timekeeping_inject_offset - Adds or subtracts from the current time.
1358 : * @ts: Pointer to the timespec variable containing the offset
1359 : *
1360 : * Adds or subtracts an offset value from the current time.
1361 : */
1362 0 : static int timekeeping_inject_offset(const struct timespec64 *ts)
1363 : {
1364 0 : struct timekeeper *tk = &tk_core.timekeeper;
1365 : unsigned long flags;
1366 : struct timespec64 tmp;
1367 0 : int ret = 0;
1368 :
1369 0 : if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1370 : return -EINVAL;
1371 :
1372 0 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
1373 0 : write_seqcount_begin(&tk_core.seq);
1374 :
1375 0 : timekeeping_forward_now(tk);
1376 :
1377 : /* Make sure the proposed value is valid */
1378 0 : tmp = timespec64_add(tk_xtime(tk), *ts);
1379 0 : if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1380 0 : !timespec64_valid_settod(&tmp)) {
1381 : ret = -EINVAL;
1382 : goto error;
1383 : }
1384 :
1385 0 : tk_xtime_add(tk, ts);
1386 0 : tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1387 :
1388 : error: /* even if we error out, we forwarded the time, so call update */
1389 0 : timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1390 :
1391 0 : write_seqcount_end(&tk_core.seq);
1392 0 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1393 :
1394 : /* Signal hrtimers about time change */
1395 0 : clock_was_set(CLOCK_SET_WALL);
1396 :
1397 0 : return ret;
1398 : }
1399 :
1400 : /*
1401 : * Indicates if there is an offset between the system clock and the hardware
1402 : * clock/persistent clock/rtc.
1403 : */
1404 : int persistent_clock_is_local;
1405 :
1406 : /*
1407 : * Adjust the time obtained from the CMOS to be UTC time instead of
1408 : * local time.
1409 : *
1410 : * This is ugly, but preferable to the alternatives. Otherwise we
1411 : * would either need to write a program to do it in /etc/rc (and risk
1412 : * confusion if the program gets run more than once; it would also be
1413 : * hard to make the program warp the clock precisely n hours) or
1414 : * compile in the timezone information into the kernel. Bad, bad....
1415 : *
1416 : * - TYT, 1992-01-01
1417 : *
1418 : * The best thing to do is to keep the CMOS clock in universal time (UTC)
1419 : * as real UNIX machines always do it. This avoids all headaches about
1420 : * daylight saving times and warping kernel clocks.
1421 : */
1422 0 : void timekeeping_warp_clock(void)
1423 : {
1424 0 : if (sys_tz.tz_minuteswest != 0) {
1425 : struct timespec64 adjust;
1426 :
1427 0 : persistent_clock_is_local = 1;
1428 0 : adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1429 0 : adjust.tv_nsec = 0;
1430 0 : timekeeping_inject_offset(&adjust);
1431 : }
1432 0 : }
1433 :
1434 : /*
1435 : * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1436 : */
1437 : static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1438 : {
1439 0 : tk->tai_offset = tai_offset;
1440 0 : tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1441 : }
1442 :
1443 : /*
1444 : * change_clocksource - Swaps clocksources if a new one is available
1445 : *
1446 : * Accumulates current time interval and initializes new clocksource
1447 : */
1448 1 : static int change_clocksource(void *data)
1449 : {
1450 1 : struct timekeeper *tk = &tk_core.timekeeper;
1451 1 : struct clocksource *new, *old = NULL;
1452 : unsigned long flags;
1453 1 : bool change = false;
1454 :
1455 1 : new = (struct clocksource *) data;
1456 :
1457 : /*
1458 : * If the cs is in module, get a module reference. Succeeds
1459 : * for built-in code (owner == NULL) as well.
1460 : */
1461 1 : if (try_module_get(new->owner)) {
1462 1 : if (!new->enable || new->enable(new) == 0)
1463 : change = true;
1464 : else
1465 0 : module_put(new->owner);
1466 : }
1467 :
1468 1 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
1469 2 : write_seqcount_begin(&tk_core.seq);
1470 :
1471 1 : timekeeping_forward_now(tk);
1472 :
1473 1 : if (change) {
1474 1 : old = tk->tkr_mono.clock;
1475 1 : tk_setup_internals(tk, new);
1476 : }
1477 :
1478 1 : timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1479 :
1480 2 : write_seqcount_end(&tk_core.seq);
1481 2 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1482 :
1483 1 : if (old) {
1484 1 : if (old->disable)
1485 0 : old->disable(old);
1486 :
1487 1 : module_put(old->owner);
1488 : }
1489 :
1490 1 : return 0;
1491 : }
1492 :
1493 : /**
1494 : * timekeeping_notify - Install a new clock source
1495 : * @clock: pointer to the clock source
1496 : *
1497 : * This function is called from clocksource.c after a new, better clock
1498 : * source has been registered. The caller holds the clocksource_mutex.
1499 : */
1500 1 : int timekeeping_notify(struct clocksource *clock)
1501 : {
1502 1 : struct timekeeper *tk = &tk_core.timekeeper;
1503 :
1504 1 : if (tk->tkr_mono.clock == clock)
1505 : return 0;
1506 1 : stop_machine(change_clocksource, clock, NULL);
1507 : tick_clock_notify();
1508 1 : return tk->tkr_mono.clock == clock ? 0 : -1;
1509 : }
1510 :
1511 : /**
1512 : * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1513 : * @ts: pointer to the timespec64 to be set
1514 : *
1515 : * Returns the raw monotonic time (completely un-modified by ntp)
1516 : */
1517 0 : void ktime_get_raw_ts64(struct timespec64 *ts)
1518 : {
1519 0 : struct timekeeper *tk = &tk_core.timekeeper;
1520 : unsigned int seq;
1521 : u64 nsecs;
1522 :
1523 : do {
1524 0 : seq = read_seqcount_begin(&tk_core.seq);
1525 0 : ts->tv_sec = tk->raw_sec;
1526 0 : nsecs = timekeeping_get_ns(&tk->tkr_raw);
1527 :
1528 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
1529 :
1530 : ts->tv_nsec = 0;
1531 0 : timespec64_add_ns(ts, nsecs);
1532 0 : }
1533 : EXPORT_SYMBOL(ktime_get_raw_ts64);
1534 :
1535 :
1536 : /**
1537 : * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1538 : */
1539 0 : int timekeeping_valid_for_hres(void)
1540 : {
1541 0 : struct timekeeper *tk = &tk_core.timekeeper;
1542 : unsigned int seq;
1543 : int ret;
1544 :
1545 : do {
1546 0 : seq = read_seqcount_begin(&tk_core.seq);
1547 :
1548 0 : ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1549 :
1550 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
1551 :
1552 0 : return ret;
1553 : }
1554 :
1555 : /**
1556 : * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1557 : */
1558 0 : u64 timekeeping_max_deferment(void)
1559 : {
1560 0 : struct timekeeper *tk = &tk_core.timekeeper;
1561 : unsigned int seq;
1562 : u64 ret;
1563 :
1564 : do {
1565 0 : seq = read_seqcount_begin(&tk_core.seq);
1566 :
1567 0 : ret = tk->tkr_mono.clock->max_idle_ns;
1568 :
1569 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
1570 :
1571 0 : return ret;
1572 : }
1573 :
1574 : /**
1575 : * read_persistent_clock64 - Return time from the persistent clock.
1576 : * @ts: Pointer to the storage for the readout value
1577 : *
1578 : * Weak dummy function for arches that do not yet support it.
1579 : * Reads the time from the battery backed persistent clock.
1580 : * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1581 : *
1582 : * XXX - Do be sure to remove it once all arches implement it.
1583 : */
1584 0 : void __weak read_persistent_clock64(struct timespec64 *ts)
1585 : {
1586 0 : ts->tv_sec = 0;
1587 0 : ts->tv_nsec = 0;
1588 0 : }
1589 :
1590 : /**
1591 : * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1592 : * from the boot.
1593 : * @wall_time: current time as returned by persistent clock
1594 : * @boot_offset: offset that is defined as wall_time - boot_time
1595 : *
1596 : * Weak dummy function for arches that do not yet support it.
1597 : *
1598 : * The default function calculates offset based on the current value of
1599 : * local_clock(). This way architectures that support sched_clock() but don't
1600 : * support dedicated boot time clock will provide the best estimate of the
1601 : * boot time.
1602 : */
1603 : void __weak __init
1604 1 : read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1605 : struct timespec64 *boot_offset)
1606 : {
1607 1 : read_persistent_clock64(wall_time);
1608 1 : *boot_offset = ns_to_timespec64(local_clock());
1609 1 : }
1610 :
1611 : /*
1612 : * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1613 : *
1614 : * The flag starts of false and is only set when a suspend reaches
1615 : * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1616 : * timekeeper clocksource is not stopping across suspend and has been
1617 : * used to update sleep time. If the timekeeper clocksource has stopped
1618 : * then the flag stays true and is used by the RTC resume code to decide
1619 : * whether sleeptime must be injected and if so the flag gets false then.
1620 : *
1621 : * If a suspend fails before reaching timekeeping_resume() then the flag
1622 : * stays false and prevents erroneous sleeptime injection.
1623 : */
1624 : static bool suspend_timing_needed;
1625 :
1626 : /* Flag for if there is a persistent clock on this platform */
1627 : static bool persistent_clock_exists;
1628 :
1629 : /*
1630 : * timekeeping_init - Initializes the clocksource and common timekeeping values
1631 : */
1632 1 : void __init timekeeping_init(void)
1633 : {
1634 : struct timespec64 wall_time, boot_offset, wall_to_mono;
1635 1 : struct timekeeper *tk = &tk_core.timekeeper;
1636 : struct clocksource *clock;
1637 : unsigned long flags;
1638 :
1639 1 : read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1640 2 : if (timespec64_valid_settod(&wall_time) &&
1641 1 : timespec64_to_ns(&wall_time) > 0) {
1642 1 : persistent_clock_exists = true;
1643 0 : } else if (timespec64_to_ns(&wall_time) != 0) {
1644 0 : pr_warn("Persistent clock returned invalid value");
1645 0 : wall_time = (struct timespec64){0};
1646 : }
1647 :
1648 1 : if (timespec64_compare(&wall_time, &boot_offset) < 0)
1649 0 : boot_offset = (struct timespec64){0};
1650 :
1651 : /*
1652 : * We want set wall_to_mono, so the following is true:
1653 : * wall time + wall_to_mono = boot time
1654 : */
1655 : wall_to_mono = timespec64_sub(boot_offset, wall_time);
1656 :
1657 1 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
1658 2 : write_seqcount_begin(&tk_core.seq);
1659 1 : ntp_init();
1660 :
1661 1 : clock = clocksource_default_clock();
1662 1 : if (clock->enable)
1663 0 : clock->enable(clock);
1664 1 : tk_setup_internals(tk, clock);
1665 :
1666 1 : tk_set_xtime(tk, &wall_time);
1667 1 : tk->raw_sec = 0;
1668 :
1669 1 : tk_set_wall_to_mono(tk, wall_to_mono);
1670 :
1671 1 : timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1672 :
1673 2 : write_seqcount_end(&tk_core.seq);
1674 2 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1675 1 : }
1676 :
1677 : /* time in seconds when suspend began for persistent clock */
1678 : static struct timespec64 timekeeping_suspend_time;
1679 :
1680 : /**
1681 : * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1682 : * @tk: Pointer to the timekeeper to be updated
1683 : * @delta: Pointer to the delta value in timespec64 format
1684 : *
1685 : * Takes a timespec offset measuring a suspend interval and properly
1686 : * adds the sleep offset to the timekeeping variables.
1687 : */
1688 0 : static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1689 : const struct timespec64 *delta)
1690 : {
1691 0 : if (!timespec64_valid_strict(delta)) {
1692 0 : printk_deferred(KERN_WARNING
1693 : "__timekeeping_inject_sleeptime: Invalid "
1694 : "sleep delta value!\n");
1695 0 : return;
1696 : }
1697 0 : tk_xtime_add(tk, delta);
1698 0 : tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1699 0 : tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1700 : tk_debug_account_sleep_time(delta);
1701 : }
1702 :
1703 : #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1704 : /*
1705 : * We have three kinds of time sources to use for sleep time
1706 : * injection, the preference order is:
1707 : * 1) non-stop clocksource
1708 : * 2) persistent clock (ie: RTC accessible when irqs are off)
1709 : * 3) RTC
1710 : *
1711 : * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1712 : * If system has neither 1) nor 2), 3) will be used finally.
1713 : *
1714 : *
1715 : * If timekeeping has injected sleeptime via either 1) or 2),
1716 : * 3) becomes needless, so in this case we don't need to call
1717 : * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1718 : * means.
1719 : */
1720 : bool timekeeping_rtc_skipresume(void)
1721 : {
1722 : return !suspend_timing_needed;
1723 : }
1724 :
1725 : /*
1726 : * 1) can be determined whether to use or not only when doing
1727 : * timekeeping_resume() which is invoked after rtc_suspend(),
1728 : * so we can't skip rtc_suspend() surely if system has 1).
1729 : *
1730 : * But if system has 2), 2) will definitely be used, so in this
1731 : * case we don't need to call rtc_suspend(), and this is what
1732 : * timekeeping_rtc_skipsuspend() means.
1733 : */
1734 : bool timekeeping_rtc_skipsuspend(void)
1735 : {
1736 : return persistent_clock_exists;
1737 : }
1738 :
1739 : /**
1740 : * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1741 : * @delta: pointer to a timespec64 delta value
1742 : *
1743 : * This hook is for architectures that cannot support read_persistent_clock64
1744 : * because their RTC/persistent clock is only accessible when irqs are enabled.
1745 : * and also don't have an effective nonstop clocksource.
1746 : *
1747 : * This function should only be called by rtc_resume(), and allows
1748 : * a suspend offset to be injected into the timekeeping values.
1749 : */
1750 : void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1751 : {
1752 : struct timekeeper *tk = &tk_core.timekeeper;
1753 : unsigned long flags;
1754 :
1755 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
1756 : write_seqcount_begin(&tk_core.seq);
1757 :
1758 : suspend_timing_needed = false;
1759 :
1760 : timekeeping_forward_now(tk);
1761 :
1762 : __timekeeping_inject_sleeptime(tk, delta);
1763 :
1764 : timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1765 :
1766 : write_seqcount_end(&tk_core.seq);
1767 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1768 :
1769 : /* Signal hrtimers about time change */
1770 : clock_was_set(CLOCK_SET_WALL | CLOCK_SET_BOOT);
1771 : }
1772 : #endif
1773 :
1774 : /**
1775 : * timekeeping_resume - Resumes the generic timekeeping subsystem.
1776 : */
1777 0 : void timekeeping_resume(void)
1778 : {
1779 0 : struct timekeeper *tk = &tk_core.timekeeper;
1780 0 : struct clocksource *clock = tk->tkr_mono.clock;
1781 : unsigned long flags;
1782 : struct timespec64 ts_new, ts_delta;
1783 : u64 cycle_now, nsec;
1784 0 : bool inject_sleeptime = false;
1785 :
1786 0 : read_persistent_clock64(&ts_new);
1787 :
1788 0 : clockevents_resume();
1789 0 : clocksource_resume();
1790 :
1791 0 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
1792 0 : write_seqcount_begin(&tk_core.seq);
1793 :
1794 : /*
1795 : * After system resumes, we need to calculate the suspended time and
1796 : * compensate it for the OS time. There are 3 sources that could be
1797 : * used: Nonstop clocksource during suspend, persistent clock and rtc
1798 : * device.
1799 : *
1800 : * One specific platform may have 1 or 2 or all of them, and the
1801 : * preference will be:
1802 : * suspend-nonstop clocksource -> persistent clock -> rtc
1803 : * The less preferred source will only be tried if there is no better
1804 : * usable source. The rtc part is handled separately in rtc core code.
1805 : */
1806 0 : cycle_now = tk_clock_read(&tk->tkr_mono);
1807 0 : nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1808 0 : if (nsec > 0) {
1809 0 : ts_delta = ns_to_timespec64(nsec);
1810 0 : inject_sleeptime = true;
1811 0 : } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1812 0 : ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1813 0 : inject_sleeptime = true;
1814 : }
1815 :
1816 0 : if (inject_sleeptime) {
1817 0 : suspend_timing_needed = false;
1818 0 : __timekeeping_inject_sleeptime(tk, &ts_delta);
1819 : }
1820 :
1821 : /* Re-base the last cycle value */
1822 0 : tk->tkr_mono.cycle_last = cycle_now;
1823 0 : tk->tkr_raw.cycle_last = cycle_now;
1824 :
1825 0 : tk->ntp_error = 0;
1826 0 : timekeeping_suspended = 0;
1827 0 : timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1828 0 : write_seqcount_end(&tk_core.seq);
1829 0 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1830 :
1831 : touch_softlockup_watchdog();
1832 :
1833 : /* Resume the clockevent device(s) and hrtimers */
1834 0 : tick_resume();
1835 : /* Notify timerfd as resume is equivalent to clock_was_set() */
1836 0 : timerfd_resume();
1837 0 : }
1838 :
1839 0 : int timekeeping_suspend(void)
1840 : {
1841 0 : struct timekeeper *tk = &tk_core.timekeeper;
1842 : unsigned long flags;
1843 : struct timespec64 delta, delta_delta;
1844 : static struct timespec64 old_delta;
1845 : struct clocksource *curr_clock;
1846 : u64 cycle_now;
1847 :
1848 0 : read_persistent_clock64(&timekeeping_suspend_time);
1849 :
1850 : /*
1851 : * On some systems the persistent_clock can not be detected at
1852 : * timekeeping_init by its return value, so if we see a valid
1853 : * value returned, update the persistent_clock_exists flag.
1854 : */
1855 0 : if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1856 0 : persistent_clock_exists = true;
1857 :
1858 0 : suspend_timing_needed = true;
1859 :
1860 0 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
1861 0 : write_seqcount_begin(&tk_core.seq);
1862 0 : timekeeping_forward_now(tk);
1863 0 : timekeeping_suspended = 1;
1864 :
1865 : /*
1866 : * Since we've called forward_now, cycle_last stores the value
1867 : * just read from the current clocksource. Save this to potentially
1868 : * use in suspend timing.
1869 : */
1870 0 : curr_clock = tk->tkr_mono.clock;
1871 0 : cycle_now = tk->tkr_mono.cycle_last;
1872 0 : clocksource_start_suspend_timing(curr_clock, cycle_now);
1873 :
1874 0 : if (persistent_clock_exists) {
1875 : /*
1876 : * To avoid drift caused by repeated suspend/resumes,
1877 : * which each can add ~1 second drift error,
1878 : * try to compensate so the difference in system time
1879 : * and persistent_clock time stays close to constant.
1880 : */
1881 0 : delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1882 : delta_delta = timespec64_sub(delta, old_delta);
1883 0 : if (abs(delta_delta.tv_sec) >= 2) {
1884 : /*
1885 : * if delta_delta is too large, assume time correction
1886 : * has occurred and set old_delta to the current delta.
1887 : */
1888 0 : old_delta = delta;
1889 : } else {
1890 : /* Otherwise try to adjust old_system to compensate */
1891 0 : timekeeping_suspend_time =
1892 : timespec64_add(timekeeping_suspend_time, delta_delta);
1893 : }
1894 : }
1895 :
1896 0 : timekeeping_update(tk, TK_MIRROR);
1897 0 : halt_fast_timekeeper(tk);
1898 0 : write_seqcount_end(&tk_core.seq);
1899 0 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1900 :
1901 0 : tick_suspend();
1902 0 : clocksource_suspend();
1903 0 : clockevents_suspend();
1904 :
1905 0 : return 0;
1906 : }
1907 :
1908 : /* sysfs resume/suspend bits for timekeeping */
1909 : static struct syscore_ops timekeeping_syscore_ops = {
1910 : .resume = timekeeping_resume,
1911 : .suspend = timekeeping_suspend,
1912 : };
1913 :
1914 1 : static int __init timekeeping_init_ops(void)
1915 : {
1916 1 : register_syscore_ops(&timekeeping_syscore_ops);
1917 1 : return 0;
1918 : }
1919 : device_initcall(timekeeping_init_ops);
1920 :
1921 : /*
1922 : * Apply a multiplier adjustment to the timekeeper
1923 : */
1924 : static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1925 : s64 offset,
1926 : s32 mult_adj)
1927 : {
1928 2747 : s64 interval = tk->cycle_interval;
1929 :
1930 2747 : if (mult_adj == 0) {
1931 : return;
1932 0 : } else if (mult_adj == -1) {
1933 0 : interval = -interval;
1934 0 : offset = -offset;
1935 0 : } else if (mult_adj != 1) {
1936 0 : interval *= mult_adj;
1937 0 : offset *= mult_adj;
1938 : }
1939 :
1940 : /*
1941 : * So the following can be confusing.
1942 : *
1943 : * To keep things simple, lets assume mult_adj == 1 for now.
1944 : *
1945 : * When mult_adj != 1, remember that the interval and offset values
1946 : * have been appropriately scaled so the math is the same.
1947 : *
1948 : * The basic idea here is that we're increasing the multiplier
1949 : * by one, this causes the xtime_interval to be incremented by
1950 : * one cycle_interval. This is because:
1951 : * xtime_interval = cycle_interval * mult
1952 : * So if mult is being incremented by one:
1953 : * xtime_interval = cycle_interval * (mult + 1)
1954 : * Its the same as:
1955 : * xtime_interval = (cycle_interval * mult) + cycle_interval
1956 : * Which can be shortened to:
1957 : * xtime_interval += cycle_interval
1958 : *
1959 : * So offset stores the non-accumulated cycles. Thus the current
1960 : * time (in shifted nanoseconds) is:
1961 : * now = (offset * adj) + xtime_nsec
1962 : * Now, even though we're adjusting the clock frequency, we have
1963 : * to keep time consistent. In other words, we can't jump back
1964 : * in time, and we also want to avoid jumping forward in time.
1965 : *
1966 : * So given the same offset value, we need the time to be the same
1967 : * both before and after the freq adjustment.
1968 : * now = (offset * adj_1) + xtime_nsec_1
1969 : * now = (offset * adj_2) + xtime_nsec_2
1970 : * So:
1971 : * (offset * adj_1) + xtime_nsec_1 =
1972 : * (offset * adj_2) + xtime_nsec_2
1973 : * And we know:
1974 : * adj_2 = adj_1 + 1
1975 : * So:
1976 : * (offset * adj_1) + xtime_nsec_1 =
1977 : * (offset * (adj_1+1)) + xtime_nsec_2
1978 : * (offset * adj_1) + xtime_nsec_1 =
1979 : * (offset * adj_1) + offset + xtime_nsec_2
1980 : * Canceling the sides:
1981 : * xtime_nsec_1 = offset + xtime_nsec_2
1982 : * Which gives us:
1983 : * xtime_nsec_2 = xtime_nsec_1 - offset
1984 : * Which simplifies to:
1985 : * xtime_nsec -= offset
1986 : */
1987 0 : if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1988 : /* NTP adjustment caused clocksource mult overflow */
1989 0 : WARN_ON_ONCE(1);
1990 : return;
1991 : }
1992 :
1993 0 : tk->tkr_mono.mult += mult_adj;
1994 0 : tk->xtime_interval += interval;
1995 0 : tk->tkr_mono.xtime_nsec -= offset;
1996 : }
1997 :
1998 : /*
1999 : * Adjust the timekeeper's multiplier to the correct frequency
2000 : * and also to reduce the accumulated error value.
2001 : */
2002 2747 : static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
2003 : {
2004 : u32 mult;
2005 :
2006 : /*
2007 : * Determine the multiplier from the current NTP tick length.
2008 : * Avoid expensive division when the tick length doesn't change.
2009 : */
2010 2747 : if (likely(tk->ntp_tick == ntp_tick_length())) {
2011 2747 : mult = tk->tkr_mono.mult - tk->ntp_err_mult;
2012 : } else {
2013 0 : tk->ntp_tick = ntp_tick_length();
2014 0 : mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
2015 0 : tk->xtime_remainder, tk->cycle_interval);
2016 : }
2017 :
2018 : /*
2019 : * If the clock is behind the NTP time, increase the multiplier by 1
2020 : * to catch up with it. If it's ahead and there was a remainder in the
2021 : * tick division, the clock will slow down. Otherwise it will stay
2022 : * ahead until the tick length changes to a non-divisible value.
2023 : */
2024 2747 : tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
2025 2747 : mult += tk->ntp_err_mult;
2026 :
2027 5494 : timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
2028 :
2029 2747 : if (unlikely(tk->tkr_mono.clock->maxadj &&
2030 : (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
2031 : > tk->tkr_mono.clock->maxadj))) {
2032 0 : printk_once(KERN_WARNING
2033 : "Adjusting %s more than 11%% (%ld vs %ld)\n",
2034 : tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
2035 : (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
2036 : }
2037 :
2038 : /*
2039 : * It may be possible that when we entered this function, xtime_nsec
2040 : * was very small. Further, if we're slightly speeding the clocksource
2041 : * in the code above, its possible the required corrective factor to
2042 : * xtime_nsec could cause it to underflow.
2043 : *
2044 : * Now, since we have already accumulated the second and the NTP
2045 : * subsystem has been notified via second_overflow(), we need to skip
2046 : * the next update.
2047 : */
2048 2747 : if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
2049 0 : tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
2050 0 : tk->tkr_mono.shift;
2051 0 : tk->xtime_sec--;
2052 0 : tk->skip_second_overflow = 1;
2053 : }
2054 2747 : }
2055 :
2056 : /*
2057 : * accumulate_nsecs_to_secs - Accumulates nsecs into secs
2058 : *
2059 : * Helper function that accumulates the nsecs greater than a second
2060 : * from the xtime_nsec field to the xtime_secs field.
2061 : * It also calls into the NTP code to handle leapsecond processing.
2062 : */
2063 5494 : static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
2064 : {
2065 5494 : u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
2066 5494 : unsigned int clock_set = 0;
2067 :
2068 11015 : while (tk->tkr_mono.xtime_nsec >= nsecps) {
2069 : int leap;
2070 :
2071 27 : tk->tkr_mono.xtime_nsec -= nsecps;
2072 27 : tk->xtime_sec++;
2073 :
2074 : /*
2075 : * Skip NTP update if this second was accumulated before,
2076 : * i.e. xtime_nsec underflowed in timekeeping_adjust()
2077 : */
2078 27 : if (unlikely(tk->skip_second_overflow)) {
2079 0 : tk->skip_second_overflow = 0;
2080 0 : continue;
2081 : }
2082 :
2083 : /* Figure out if its a leap sec and apply if needed */
2084 27 : leap = second_overflow(tk->xtime_sec);
2085 27 : if (unlikely(leap)) {
2086 : struct timespec64 ts;
2087 :
2088 0 : tk->xtime_sec += leap;
2089 :
2090 0 : ts.tv_sec = leap;
2091 0 : ts.tv_nsec = 0;
2092 0 : tk_set_wall_to_mono(tk,
2093 : timespec64_sub(tk->wall_to_monotonic, ts));
2094 :
2095 0 : __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
2096 :
2097 0 : clock_set = TK_CLOCK_WAS_SET;
2098 : }
2099 : }
2100 5494 : return clock_set;
2101 : }
2102 :
2103 : /*
2104 : * logarithmic_accumulation - shifted accumulation of cycles
2105 : *
2106 : * This functions accumulates a shifted interval of cycles into
2107 : * a shifted interval nanoseconds. Allows for O(log) accumulation
2108 : * loop.
2109 : *
2110 : * Returns the unconsumed cycles.
2111 : */
2112 5475 : static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2113 : u32 shift, unsigned int *clock_set)
2114 : {
2115 5475 : u64 interval = tk->cycle_interval << shift;
2116 : u64 snsec_per_sec;
2117 :
2118 : /* If the offset is smaller than a shifted interval, do nothing */
2119 5475 : if (offset < interval)
2120 : return offset;
2121 :
2122 : /* Accumulate one shifted interval */
2123 2747 : offset -= interval;
2124 2747 : tk->tkr_mono.cycle_last += interval;
2125 2747 : tk->tkr_raw.cycle_last += interval;
2126 :
2127 2747 : tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2128 2747 : *clock_set |= accumulate_nsecs_to_secs(tk);
2129 :
2130 : /* Accumulate raw time */
2131 2747 : tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2132 2747 : snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2133 5521 : while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2134 27 : tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2135 27 : tk->raw_sec++;
2136 : }
2137 :
2138 : /* Accumulate error between NTP and clock interval */
2139 2747 : tk->ntp_error += tk->ntp_tick << shift;
2140 5494 : tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2141 2747 : (tk->ntp_error_shift + shift);
2142 :
2143 2747 : return offset;
2144 : }
2145 :
2146 : /*
2147 : * timekeeping_advance - Updates the timekeeper to the current time and
2148 : * current NTP tick length
2149 : */
2150 2751 : static bool timekeeping_advance(enum timekeeping_adv_mode mode)
2151 : {
2152 2751 : struct timekeeper *real_tk = &tk_core.timekeeper;
2153 2751 : struct timekeeper *tk = &shadow_timekeeper;
2154 : u64 offset;
2155 2751 : int shift = 0, maxshift;
2156 2751 : unsigned int clock_set = 0;
2157 : unsigned long flags;
2158 :
2159 2751 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
2160 :
2161 : /* Make sure we're fully resumed: */
2162 2751 : if (unlikely(timekeeping_suspended))
2163 : goto out;
2164 :
2165 8253 : offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2166 : tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2167 :
2168 : /* Check if there's really nothing to do */
2169 2751 : if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2170 : goto out;
2171 :
2172 : /* Do some additional sanity checking */
2173 2747 : timekeeping_check_update(tk, offset);
2174 :
2175 : /*
2176 : * With NO_HZ we may have to accumulate many cycle_intervals
2177 : * (think "ticks") worth of time at once. To do this efficiently,
2178 : * we calculate the largest doubling multiple of cycle_intervals
2179 : * that is smaller than the offset. We then accumulate that
2180 : * chunk in one go, and then try to consume the next smaller
2181 : * doubled multiple.
2182 : */
2183 8241 : shift = ilog2(offset) - ilog2(tk->cycle_interval);
2184 2747 : shift = max(0, shift);
2185 : /* Bound shift to one less than what overflows tick_length */
2186 5494 : maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2187 2747 : shift = min(shift, maxshift);
2188 10969 : while (offset >= tk->cycle_interval) {
2189 5475 : offset = logarithmic_accumulation(tk, offset, shift,
2190 : &clock_set);
2191 5475 : if (offset < tk->cycle_interval<<shift)
2192 5475 : shift--;
2193 : }
2194 :
2195 : /* Adjust the multiplier to correct NTP error */
2196 2747 : timekeeping_adjust(tk, offset);
2197 :
2198 : /*
2199 : * Finally, make sure that after the rounding
2200 : * xtime_nsec isn't larger than NSEC_PER_SEC
2201 : */
2202 2747 : clock_set |= accumulate_nsecs_to_secs(tk);
2203 :
2204 5494 : write_seqcount_begin(&tk_core.seq);
2205 : /*
2206 : * Update the real timekeeper.
2207 : *
2208 : * We could avoid this memcpy by switching pointers, but that
2209 : * requires changes to all other timekeeper usage sites as
2210 : * well, i.e. move the timekeeper pointer getter into the
2211 : * spinlocked/seqcount protected sections. And we trade this
2212 : * memcpy under the tk_core.seq against one before we start
2213 : * updating.
2214 : */
2215 2747 : timekeeping_update(tk, clock_set);
2216 2747 : memcpy(real_tk, tk, sizeof(*tk));
2217 : /* The memcpy must come last. Do not put anything here! */
2218 5494 : write_seqcount_end(&tk_core.seq);
2219 : out:
2220 5502 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2221 :
2222 2751 : return !!clock_set;
2223 : }
2224 :
2225 : /**
2226 : * update_wall_time - Uses the current clocksource to increment the wall time
2227 : *
2228 : */
2229 2751 : void update_wall_time(void)
2230 : {
2231 2751 : if (timekeeping_advance(TK_ADV_TICK))
2232 0 : clock_was_set_delayed();
2233 2751 : }
2234 :
2235 : /**
2236 : * getboottime64 - Return the real time of system boot.
2237 : * @ts: pointer to the timespec64 to be set
2238 : *
2239 : * Returns the wall-time of boot in a timespec64.
2240 : *
2241 : * This is based on the wall_to_monotonic offset and the total suspend
2242 : * time. Calls to settimeofday will affect the value returned (which
2243 : * basically means that however wrong your real time clock is at boot time,
2244 : * you get the right time here).
2245 : */
2246 0 : void getboottime64(struct timespec64 *ts)
2247 : {
2248 0 : struct timekeeper *tk = &tk_core.timekeeper;
2249 0 : ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2250 :
2251 0 : *ts = ktime_to_timespec64(t);
2252 0 : }
2253 : EXPORT_SYMBOL_GPL(getboottime64);
2254 :
2255 54 : void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2256 : {
2257 54 : struct timekeeper *tk = &tk_core.timekeeper;
2258 : unsigned int seq;
2259 :
2260 : do {
2261 54 : seq = read_seqcount_begin(&tk_core.seq);
2262 :
2263 54 : *ts = tk_xtime(tk);
2264 108 : } while (read_seqcount_retry(&tk_core.seq, seq));
2265 54 : }
2266 : EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2267 :
2268 0 : void ktime_get_coarse_ts64(struct timespec64 *ts)
2269 : {
2270 0 : struct timekeeper *tk = &tk_core.timekeeper;
2271 : struct timespec64 now, mono;
2272 : unsigned int seq;
2273 :
2274 : do {
2275 0 : seq = read_seqcount_begin(&tk_core.seq);
2276 :
2277 0 : now = tk_xtime(tk);
2278 0 : mono = tk->wall_to_monotonic;
2279 0 : } while (read_seqcount_retry(&tk_core.seq, seq));
2280 :
2281 0 : set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2282 0 : now.tv_nsec + mono.tv_nsec);
2283 0 : }
2284 : EXPORT_SYMBOL(ktime_get_coarse_ts64);
2285 :
2286 : /*
2287 : * Must hold jiffies_lock
2288 : */
2289 2751 : void do_timer(unsigned long ticks)
2290 : {
2291 2751 : jiffies_64 += ticks;
2292 2751 : calc_global_load();
2293 2751 : }
2294 :
2295 : /**
2296 : * ktime_get_update_offsets_now - hrtimer helper
2297 : * @cwsseq: pointer to check and store the clock was set sequence number
2298 : * @offs_real: pointer to storage for monotonic -> realtime offset
2299 : * @offs_boot: pointer to storage for monotonic -> boottime offset
2300 : * @offs_tai: pointer to storage for monotonic -> clock tai offset
2301 : *
2302 : * Returns current monotonic time and updates the offsets if the
2303 : * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2304 : * different.
2305 : *
2306 : * Called from hrtimer_interrupt() or retrigger_next_event()
2307 : */
2308 2751 : ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2309 : ktime_t *offs_boot, ktime_t *offs_tai)
2310 : {
2311 2751 : struct timekeeper *tk = &tk_core.timekeeper;
2312 : unsigned int seq;
2313 : ktime_t base;
2314 : u64 nsecs;
2315 :
2316 : do {
2317 2751 : seq = read_seqcount_begin(&tk_core.seq);
2318 :
2319 2751 : base = tk->tkr_mono.base;
2320 5502 : nsecs = timekeeping_get_ns(&tk->tkr_mono);
2321 2751 : base = ktime_add_ns(base, nsecs);
2322 :
2323 2751 : if (*cwsseq != tk->clock_was_set_seq) {
2324 2 : *cwsseq = tk->clock_was_set_seq;
2325 2 : *offs_real = tk->offs_real;
2326 2 : *offs_boot = tk->offs_boot;
2327 2 : *offs_tai = tk->offs_tai;
2328 : }
2329 :
2330 : /* Handle leapsecond insertion adjustments */
2331 2751 : if (unlikely(base >= tk->next_leap_ktime))
2332 0 : *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2333 :
2334 5502 : } while (read_seqcount_retry(&tk_core.seq, seq));
2335 :
2336 2751 : return base;
2337 : }
2338 :
2339 : /*
2340 : * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2341 : */
2342 0 : static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2343 : {
2344 0 : if (txc->modes & ADJ_ADJTIME) {
2345 : /* singleshot must not be used with any other mode bits */
2346 0 : if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2347 : return -EINVAL;
2348 0 : if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2349 0 : !capable(CAP_SYS_TIME))
2350 : return -EPERM;
2351 : } else {
2352 : /* In order to modify anything, you gotta be super-user! */
2353 0 : if (txc->modes && !capable(CAP_SYS_TIME))
2354 : return -EPERM;
2355 : /*
2356 : * if the quartz is off by more than 10% then
2357 : * something is VERY wrong!
2358 : */
2359 0 : if (txc->modes & ADJ_TICK &&
2360 0 : (txc->tick < 900000/USER_HZ ||
2361 : txc->tick > 1100000/USER_HZ))
2362 : return -EINVAL;
2363 : }
2364 :
2365 0 : if (txc->modes & ADJ_SETOFFSET) {
2366 : /* In order to inject time, you gotta be super-user! */
2367 0 : if (!capable(CAP_SYS_TIME))
2368 : return -EPERM;
2369 :
2370 : /*
2371 : * Validate if a timespec/timeval used to inject a time
2372 : * offset is valid. Offsets can be positive or negative, so
2373 : * we don't check tv_sec. The value of the timeval/timespec
2374 : * is the sum of its fields,but *NOTE*:
2375 : * The field tv_usec/tv_nsec must always be non-negative and
2376 : * we can't have more nanoseconds/microseconds than a second.
2377 : */
2378 0 : if (txc->time.tv_usec < 0)
2379 : return -EINVAL;
2380 :
2381 0 : if (txc->modes & ADJ_NANO) {
2382 0 : if (txc->time.tv_usec >= NSEC_PER_SEC)
2383 : return -EINVAL;
2384 : } else {
2385 0 : if (txc->time.tv_usec >= USEC_PER_SEC)
2386 : return -EINVAL;
2387 : }
2388 : }
2389 :
2390 : /*
2391 : * Check for potential multiplication overflows that can
2392 : * only happen on 64-bit systems:
2393 : */
2394 0 : if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2395 0 : if (LLONG_MIN / PPM_SCALE > txc->freq)
2396 : return -EINVAL;
2397 0 : if (LLONG_MAX / PPM_SCALE < txc->freq)
2398 : return -EINVAL;
2399 : }
2400 :
2401 0 : return 0;
2402 : }
2403 :
2404 : /**
2405 : * random_get_entropy_fallback - Returns the raw clock source value,
2406 : * used by random.c for platforms with no valid random_get_entropy().
2407 : */
2408 3612 : unsigned long random_get_entropy_fallback(void)
2409 : {
2410 3612 : struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono;
2411 3612 : struct clocksource *clock = READ_ONCE(tkr->clock);
2412 :
2413 3612 : if (unlikely(timekeeping_suspended || !clock))
2414 : return 0;
2415 3612 : return clock->read(clock);
2416 : }
2417 : EXPORT_SYMBOL_GPL(random_get_entropy_fallback);
2418 :
2419 : /**
2420 : * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2421 : */
2422 0 : int do_adjtimex(struct __kernel_timex *txc)
2423 : {
2424 0 : struct timekeeper *tk = &tk_core.timekeeper;
2425 : struct audit_ntp_data ad;
2426 0 : bool clock_set = false;
2427 : struct timespec64 ts;
2428 : unsigned long flags;
2429 : s32 orig_tai, tai;
2430 : int ret;
2431 :
2432 : /* Validate the data before disabling interrupts */
2433 0 : ret = timekeeping_validate_timex(txc);
2434 0 : if (ret)
2435 : return ret;
2436 0 : add_device_randomness(txc, sizeof(*txc));
2437 :
2438 0 : if (txc->modes & ADJ_SETOFFSET) {
2439 : struct timespec64 delta;
2440 0 : delta.tv_sec = txc->time.tv_sec;
2441 0 : delta.tv_nsec = txc->time.tv_usec;
2442 0 : if (!(txc->modes & ADJ_NANO))
2443 0 : delta.tv_nsec *= 1000;
2444 0 : ret = timekeeping_inject_offset(&delta);
2445 0 : if (ret)
2446 0 : return ret;
2447 :
2448 0 : audit_tk_injoffset(delta);
2449 : }
2450 :
2451 0 : audit_ntp_init(&ad);
2452 :
2453 0 : ktime_get_real_ts64(&ts);
2454 0 : add_device_randomness(&ts, sizeof(ts));
2455 :
2456 0 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
2457 0 : write_seqcount_begin(&tk_core.seq);
2458 :
2459 0 : orig_tai = tai = tk->tai_offset;
2460 0 : ret = __do_adjtimex(txc, &ts, &tai, &ad);
2461 :
2462 0 : if (tai != orig_tai) {
2463 0 : __timekeeping_set_tai_offset(tk, tai);
2464 0 : timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2465 0 : clock_set = true;
2466 : }
2467 0 : tk_update_leap_state(tk);
2468 :
2469 0 : write_seqcount_end(&tk_core.seq);
2470 0 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2471 :
2472 0 : audit_ntp_log(&ad);
2473 :
2474 : /* Update the multiplier immediately if frequency was set directly */
2475 0 : if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2476 0 : clock_set |= timekeeping_advance(TK_ADV_FREQ);
2477 :
2478 0 : if (clock_set)
2479 0 : clock_was_set(CLOCK_REALTIME);
2480 :
2481 : ntp_notify_cmos_timer();
2482 :
2483 : return ret;
2484 : }
2485 :
2486 : #ifdef CONFIG_NTP_PPS
2487 : /**
2488 : * hardpps() - Accessor function to NTP __hardpps function
2489 : */
2490 : void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2491 : {
2492 : unsigned long flags;
2493 :
2494 : raw_spin_lock_irqsave(&timekeeper_lock, flags);
2495 : write_seqcount_begin(&tk_core.seq);
2496 :
2497 : __hardpps(phase_ts, raw_ts);
2498 :
2499 : write_seqcount_end(&tk_core.seq);
2500 : raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2501 : }
2502 : EXPORT_SYMBOL(hardpps);
2503 : #endif /* CONFIG_NTP_PPS */
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