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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
36enum 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
44DEFINE_RAW_SPINLOCK(timekeeper_lock);
45
46/*
47 * The most important data for readout fits into a single 64 byte
48 * cache line.
49 */
50static 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
57static struct timekeeper shadow_timekeeper;
58
59/* flag for if timekeeping is suspended */
60int __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 */
71struct 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. */
77static u64 cycles_at_suspend;
78
79static u64 dummy_clock_read(struct clocksource *cs)
80{
81 if (timekeeping_suspended)
82 return cycles_at_suspend;
83 return local_clock();
84}
85
86static 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
105static 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
111static 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
117static inline void tk_normalize_xtime(struct timekeeper *tk)
118{
119 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
120 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
121 tk->xtime_sec++;
122 }
123 while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
124 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
125 tk->raw_sec++;
126 }
127}
128
129static inline struct timespec64 tk_xtime(const struct timekeeper *tk)
130{
131 struct timespec64 ts;
132
133 ts.tv_sec = tk->xtime_sec;
134 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
135 return ts;
136}
137
138static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
139{
140 tk->xtime_sec = ts->tv_sec;
141 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
142}
143
144static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
145{
146 tk->xtime_sec += ts->tv_sec;
147 tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
148 tk_normalize_xtime(tk);
149}
150
151static 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 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
160 -tk->wall_to_monotonic.tv_nsec);
161 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
162 tk->wall_to_monotonic = wtm;
163 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
164 tk->offs_real = timespec64_to_ktime(tmp);
165 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
166}
167
168static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
169{
170 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 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 */
191static inline u64 tk_clock_read(const struct tk_read_base *tkr)
192{
193 struct clocksource *clock = READ_ONCE(tkr->clock);
194
195 return clock->read(clock);
196}
197
198#ifdef CONFIG_DEBUG_TIMEKEEPING
199#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
200
201static 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
240static 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
281static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
282{
283}
284static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
285{
286 u64 cycle_now, delta;
287
288 /* read clocksource */
289 cycle_now = tk_clock_read(tkr);
290
291 /* calculate the delta since the last update_wall_time */
292 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 */
309static 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 ++tk->cs_was_changed_seq;
316 old_clock = tk->tkr_mono.clock;
317 tk->tkr_mono.clock = clock;
318 tk->tkr_mono.mask = clock->mask;
319 tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
320
321 tk->tkr_raw.clock = clock;
322 tk->tkr_raw.mask = clock->mask;
323 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
324
325 /* Do the ns -> cycle conversion first, using original mult */
326 tmp = NTP_INTERVAL_LENGTH;
327 tmp <<= clock->shift;
328 ntpinterval = tmp;
329 tmp += clock->mult/2;
330 do_div(tmp, clock->mult);
331 if (tmp == 0)
332 tmp = 1;
333
334 interval = (u64) tmp;
335 tk->cycle_interval = interval;
336
337 /* Go back from cycles -> shifted ns */
338 tk->xtime_interval = interval * clock->mult;
339 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
340 tk->raw_interval = interval * clock->mult;
341
342 /* if changing clocks, convert xtime_nsec shift units */
343 if (old_clock) {
344 int shift_change = clock->shift - old_clock->shift;
345 if (shift_change < 0) {
346 tk->tkr_mono.xtime_nsec >>= -shift_change;
347 tk->tkr_raw.xtime_nsec >>= -shift_change;
348 } else {
349 tk->tkr_mono.xtime_nsec <<= shift_change;
350 tk->tkr_raw.xtime_nsec <<= shift_change;
351 }
352 }
353
354 tk->tkr_mono.shift = clock->shift;
355 tk->tkr_raw.shift = clock->shift;
356
357 tk->ntp_error = 0;
358 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
359 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 tk->tkr_mono.mult = clock->mult;
367 tk->tkr_raw.mult = clock->mult;
368 tk->ntp_err_mult = 0;
369 tk->skip_second_overflow = 0;
370}
371
372/* Timekeeper helper functions. */
373
374static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta)
375{
376 u64 nsec;
377
378 nsec = delta * tkr->mult + tkr->xtime_nsec;
379 nsec >>= tkr->shift;
380
381 return nsec;
382}
383
384static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
385{
386 u64 delta;
387
388 delta = timekeeping_get_delta(tkr);
389 return timekeeping_delta_to_ns(tkr, delta);
390}
391
392static 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 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
398 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 */
416static void update_fast_timekeeper(const struct tk_read_base *tkr,
417 struct tk_fast *tkf)
418{
419 struct tk_read_base *base = tkf->base;
420
421 /* Force readers off to base[1] */
422 raw_write_seqcount_latch(&tkf->seq);
423
424 /* Update base[0] */
425 memcpy(base, tkr, sizeof(*base));
426
427 /* Force readers back to base[0] */
428 raw_write_seqcount_latch(&tkf->seq);
429
430 /* Update base[1] */
431 memcpy(base + 1, base, sizeof(*base));
432}
433
434static __always_inline u64 fast_tk_get_delta_ns(struct tk_read_base *tkr)
435{
436 u64 delta, cycles = tk_clock_read(tkr);
437
438 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
439 return timekeeping_delta_to_ns(tkr, delta);
440}
441
442static __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 seq = raw_read_seqcount_latch(&tkf->seq);
450 tkr = tkf->base + (seq & 0x01);
451 now = ktime_to_ns(tkr->base);
452 now += fast_tk_get_delta_ns(tkr);
453 } while (raw_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 */
490u64 notrace ktime_get_mono_fast_ns(void)
491{
492 return __ktime_get_fast_ns(&tk_fast_mono);
493}
494EXPORT_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 */
502u64 notrace ktime_get_raw_fast_ns(void)
503{
504 return __ktime_get_fast_ns(&tk_fast_raw);
505}
506EXPORT_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_mono_fast_ns()
530 * apply as well.
531 */
532u64 notrace ktime_get_boot_fast_ns(void)
533{
534 struct timekeeper *tk = &tk_core.timekeeper;
535
536 return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_boot)));
537}
538EXPORT_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 */
549u64 notrace ktime_get_tai_fast_ns(void)
550{
551 struct timekeeper *tk = &tk_core.timekeeper;
552
553 return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_tai)));
554}
555EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns);
556
557static __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 seq = raw_read_seqcount_latch(&tkf->seq);
565 tkr = tkf->base + (seq & 0x01);
566 basem = ktime_to_ns(tkr->base);
567 baser = ktime_to_ns(tkr->base_real);
568 delta = fast_tk_get_delta_ns(tkr);
569 } while (raw_read_seqcount_latch_retry(&tkf->seq, seq));
570
571 if (mono)
572 *mono = basem + delta;
573 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_mono_fast_ns() for documentation of the time stamp ordering.
580 */
581u64 ktime_get_real_fast_ns(void)
582{
583 return __ktime_get_real_fast(&tk_fast_mono, NULL);
584}
585EXPORT_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 */
633void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot)
634{
635 struct timekeeper *tk = &tk_core.timekeeper;
636
637 snapshot->real = __ktime_get_real_fast(&tk_fast_mono, &snapshot->mono);
638 snapshot->boot = snapshot->mono + ktime_to_ns(data_race(tk->offs_boot));
639}
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 */
651static void halt_fast_timekeeper(const struct timekeeper *tk)
652{
653 static struct tk_read_base tkr_dummy;
654 const struct tk_read_base *tkr = &tk->tkr_mono;
655
656 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
657 cycles_at_suspend = tk_clock_read(tkr);
658 tkr_dummy.clock = &dummy_clock;
659 tkr_dummy.base_real = tkr->base + tk->offs_real;
660 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
661
662 tkr = &tk->tkr_raw;
663 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
664 tkr_dummy.clock = &dummy_clock;
665 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
666}
667
668static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
669
670static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
671{
672 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 */
679int pvclock_gtod_register_notifier(struct notifier_block *nb)
680{
681 struct timekeeper *tk = &tk_core.timekeeper;
682 unsigned long flags;
683 int ret;
684
685 raw_spin_lock_irqsave(&timekeeper_lock, flags);
686 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
687 update_pvclock_gtod(tk, true);
688 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
689
690 return ret;
691}
692EXPORT_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 */
699int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
700{
701 unsigned long flags;
702 int ret;
703
704 raw_spin_lock_irqsave(&timekeeper_lock, flags);
705 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
706 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
707
708 return ret;
709}
710EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
711
712/*
713 * tk_update_leap_state - helper to update the next_leap_ktime
714 */
715static inline void tk_update_leap_state(struct timekeeper *tk)
716{
717 tk->next_leap_ktime = ntp_get_next_leap();
718 if (tk->next_leap_ktime != KTIME_MAX)
719 /* Convert to monotonic time */
720 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 */
726static 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 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
739 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
740 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 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
748 if (nsec >= NSEC_PER_SEC)
749 seconds++;
750 tk->ktime_sec = seconds;
751
752 /* Update the monotonic raw base */
753 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
754}
755
756/* must hold timekeeper_lock */
757static void timekeeping_update(struct timekeeper *tk, unsigned int action)
758{
759 if (action & TK_CLEAR_NTP) {
760 tk->ntp_error = 0;
761 ntp_clear();
762 }
763
764 tk_update_leap_state(tk);
765 tk_update_ktime_data(tk);
766
767 update_vsyscall(tk);
768 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
769
770 tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
771 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
772 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
773
774 if (action & TK_CLOCK_WAS_SET)
775 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 if (action & TK_MIRROR)
782 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
783 sizeof(tk_core.timekeeper));
784}
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 */
794static void timekeeping_forward_now(struct timekeeper *tk)
795{
796 u64 cycle_now, delta;
797
798 cycle_now = tk_clock_read(&tk->tkr_mono);
799 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
800 tk->tkr_mono.cycle_last = cycle_now;
801 tk->tkr_raw.cycle_last = cycle_now;
802
803 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
804 tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
805
806 tk_normalize_xtime(tk);
807}
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 */
815void ktime_get_real_ts64(struct timespec64 *ts)
816{
817 struct timekeeper *tk = &tk_core.timekeeper;
818 unsigned int seq;
819 u64 nsecs;
820
821 WARN_ON(timekeeping_suspended);
822
823 do {
824 seq = read_seqcount_begin(&tk_core.seq);
825
826 ts->tv_sec = tk->xtime_sec;
827 nsecs = timekeeping_get_ns(&tk->tkr_mono);
828
829 } while (read_seqcount_retry(&tk_core.seq, seq));
830
831 ts->tv_nsec = 0;
832 timespec64_add_ns(ts, nsecs);
833}
834EXPORT_SYMBOL(ktime_get_real_ts64);
835
836ktime_t ktime_get(void)
837{
838 struct timekeeper *tk = &tk_core.timekeeper;
839 unsigned int seq;
840 ktime_t base;
841 u64 nsecs;
842
843 WARN_ON(timekeeping_suspended);
844
845 do {
846 seq = read_seqcount_begin(&tk_core.seq);
847 base = tk->tkr_mono.base;
848 nsecs = timekeeping_get_ns(&tk->tkr_mono);
849
850 } while (read_seqcount_retry(&tk_core.seq, seq));
851
852 return ktime_add_ns(base, nsecs);
853}
854EXPORT_SYMBOL_GPL(ktime_get);
855
856u32 ktime_get_resolution_ns(void)
857{
858 struct timekeeper *tk = &tk_core.timekeeper;
859 unsigned int seq;
860 u32 nsecs;
861
862 WARN_ON(timekeeping_suspended);
863
864 do {
865 seq = read_seqcount_begin(&tk_core.seq);
866 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
867 } while (read_seqcount_retry(&tk_core.seq, seq));
868
869 return nsecs;
870}
871EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
872
873static 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
879ktime_t ktime_get_with_offset(enum tk_offsets offs)
880{
881 struct timekeeper *tk = &tk_core.timekeeper;
882 unsigned int seq;
883 ktime_t base, *offset = offsets[offs];
884 u64 nsecs;
885
886 WARN_ON(timekeeping_suspended);
887
888 do {
889 seq = read_seqcount_begin(&tk_core.seq);
890 base = ktime_add(tk->tkr_mono.base, *offset);
891 nsecs = timekeeping_get_ns(&tk->tkr_mono);
892
893 } while (read_seqcount_retry(&tk_core.seq, seq));
894
895 return ktime_add_ns(base, nsecs);
896
897}
898EXPORT_SYMBOL_GPL(ktime_get_with_offset);
899
900ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
901{
902 struct timekeeper *tk = &tk_core.timekeeper;
903 unsigned int seq;
904 ktime_t base, *offset = offsets[offs];
905 u64 nsecs;
906
907 WARN_ON(timekeeping_suspended);
908
909 do {
910 seq = read_seqcount_begin(&tk_core.seq);
911 base = ktime_add(tk->tkr_mono.base, *offset);
912 nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
913
914 } while (read_seqcount_retry(&tk_core.seq, seq));
915
916 return ktime_add_ns(base, nsecs);
917}
918EXPORT_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 */
925ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
926{
927 ktime_t *offset = offsets[offs];
928 unsigned int seq;
929 ktime_t tconv;
930
931 do {
932 seq = read_seqcount_begin(&tk_core.seq);
933 tconv = ktime_add(tmono, *offset);
934 } while (read_seqcount_retry(&tk_core.seq, seq));
935
936 return tconv;
937}
938EXPORT_SYMBOL_GPL(ktime_mono_to_any);
939
940/**
941 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
942 */
943ktime_t ktime_get_raw(void)
944{
945 struct timekeeper *tk = &tk_core.timekeeper;
946 unsigned int seq;
947 ktime_t base;
948 u64 nsecs;
949
950 do {
951 seq = read_seqcount_begin(&tk_core.seq);
952 base = tk->tkr_raw.base;
953 nsecs = timekeeping_get_ns(&tk->tkr_raw);
954
955 } while (read_seqcount_retry(&tk_core.seq, seq));
956
957 return ktime_add_ns(base, nsecs);
958}
959EXPORT_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 */
969void ktime_get_ts64(struct timespec64 *ts)
970{
971 struct timekeeper *tk = &tk_core.timekeeper;
972 struct timespec64 tomono;
973 unsigned int seq;
974 u64 nsec;
975
976 WARN_ON(timekeeping_suspended);
977
978 do {
979 seq = read_seqcount_begin(&tk_core.seq);
980 ts->tv_sec = tk->xtime_sec;
981 nsec = timekeeping_get_ns(&tk->tkr_mono);
982 tomono = tk->wall_to_monotonic;
983
984 } while (read_seqcount_retry(&tk_core.seq, seq));
985
986 ts->tv_sec += tomono.tv_sec;
987 ts->tv_nsec = 0;
988 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
989}
990EXPORT_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 */
1001time64_t ktime_get_seconds(void)
1002{
1003 struct timekeeper *tk = &tk_core.timekeeper;
1004
1005 WARN_ON(timekeeping_suspended);
1006 return tk->ktime_sec;
1007}
1008EXPORT_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 */
1020time64_t ktime_get_real_seconds(void)
1021{
1022 struct timekeeper *tk = &tk_core.timekeeper;
1023 time64_t seconds;
1024 unsigned int seq;
1025
1026 if (IS_ENABLED(CONFIG_64BIT))
1027 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}
1037EXPORT_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 */
1044noinstr time64_t __ktime_get_real_seconds(void)
1045{
1046 struct timekeeper *tk = &tk_core.timekeeper;
1047
1048 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 */
1055void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
1056{
1057 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 WARN_ON_ONCE(timekeeping_suspended);
1066
1067 do {
1068 seq = read_seqcount_begin(&tk_core.seq);
1069 now = tk_clock_read(&tk->tkr_mono);
1070 systime_snapshot->cs_id = tk->tkr_mono.clock->id;
1071 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
1072 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
1073 base_real = ktime_add(tk->tkr_mono.base,
1074 tk_core.timekeeper.offs_real);
1075 base_raw = tk->tkr_raw.base;
1076 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
1077 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
1078 } while (read_seqcount_retry(&tk_core.seq, seq));
1079
1080 systime_snapshot->cycles = now;
1081 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
1082 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
1083}
1084EXPORT_SYMBOL_GPL(ktime_get_snapshot);
1085
1086/* Scale base by mult/div checking for overflow */
1087static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1088{
1089 u64 tmp, rem;
1090
1091 tmp = div64_u64_rem(*base, div, &rem);
1092
1093 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1094 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1095 return -EOVERFLOW;
1096 tmp *= mult;
1097
1098 rem = div64_u64(rem * mult, div);
1099 *base = tmp + rem;
1100 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 */
1120static 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 struct timekeeper *tk = &tk_core.timekeeper;
1127 u64 corr_raw, corr_real;
1128 bool interp_forward;
1129 int ret;
1130
1131 if (total_history_cycles == 0 || partial_history_cycles == 0)
1132 return 0;
1133
1134 /* Interpolate shortest distance from beginning or end of history */
1135 interp_forward = partial_history_cycles > total_history_cycles / 2;
1136 partial_history_cycles = interp_forward ?
1137 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 corr_raw = (u64)ktime_to_ns(
1145 ktime_sub(ts->sys_monoraw, history->raw));
1146 ret = scale64_check_overflow(partial_history_cycles,
1147 total_history_cycles, &corr_raw);
1148 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 if (discontinuity) {
1159 corr_real = mul_u64_u32_div
1160 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1161 } else {
1162 corr_real = (u64)ktime_to_ns(
1163 ktime_sub(ts->sys_realtime, history->real));
1164 ret = scale64_check_overflow(partial_history_cycles,
1165 total_history_cycles, &corr_real);
1166 if (ret)
1167 return ret;
1168 }
1169
1170 /* Fixup monotonic raw and real time time values */
1171 if (interp_forward) {
1172 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1173 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1174 } else {
1175 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1176 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1177 }
1178
1179 return 0;
1180}
1181
1182/*
1183 * timestamp_in_interval - true if ts is chronologically in [start, end]
1184 *
1185 * True if ts occurs chronologically at or after start, and before or at end.
1186 */
1187static bool timestamp_in_interval(u64 start, u64 end, u64 ts)
1188{
1189 if (ts >= start && ts <= end)
1190 return true;
1191 if (start > end && (ts >= start || ts <= end))
1192 return true;
1193 return false;
1194}
1195
1196/**
1197 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1198 * @get_time_fn: Callback to get simultaneous device time and
1199 * system counter from the device driver
1200 * @ctx: Context passed to get_time_fn()
1201 * @history_begin: Historical reference point used to interpolate system
1202 * time when counter provided by the driver is before the current interval
1203 * @xtstamp: Receives simultaneously captured system and device time
1204 *
1205 * Reads a timestamp from a device and correlates it to system time
1206 */
1207int get_device_system_crosststamp(int (*get_time_fn)
1208 (ktime_t *device_time,
1209 struct system_counterval_t *sys_counterval,
1210 void *ctx),
1211 void *ctx,
1212 struct system_time_snapshot *history_begin,
1213 struct system_device_crosststamp *xtstamp)
1214{
1215 struct system_counterval_t system_counterval;
1216 struct timekeeper *tk = &tk_core.timekeeper;
1217 u64 cycles, now, interval_start;
1218 unsigned int clock_was_set_seq = 0;
1219 ktime_t base_real, base_raw;
1220 u64 nsec_real, nsec_raw;
1221 u8 cs_was_changed_seq;
1222 unsigned int seq;
1223 bool do_interp;
1224 int ret;
1225
1226 do {
1227 seq = read_seqcount_begin(&tk_core.seq);
1228 /*
1229 * Try to synchronously capture device time and a system
1230 * counter value calling back into the device driver
1231 */
1232 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1233 if (ret)
1234 return ret;
1235
1236 /*
1237 * Verify that the clocksource ID associated with the captured
1238 * system counter value is the same as for the currently
1239 * installed timekeeper clocksource
1240 */
1241 if (system_counterval.cs_id == CSID_GENERIC ||
1242 tk->tkr_mono.clock->id != system_counterval.cs_id)
1243 return -ENODEV;
1244 cycles = system_counterval.cycles;
1245
1246 /*
1247 * Check whether the system counter value provided by the
1248 * device driver is on the current timekeeping interval.
1249 */
1250 now = tk_clock_read(&tk->tkr_mono);
1251 interval_start = tk->tkr_mono.cycle_last;
1252 if (!timestamp_in_interval(interval_start, now, cycles)) {
1253 clock_was_set_seq = tk->clock_was_set_seq;
1254 cs_was_changed_seq = tk->cs_was_changed_seq;
1255 cycles = interval_start;
1256 do_interp = true;
1257 } else {
1258 do_interp = false;
1259 }
1260
1261 base_real = ktime_add(tk->tkr_mono.base,
1262 tk_core.timekeeper.offs_real);
1263 base_raw = tk->tkr_raw.base;
1264
1265 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, cycles);
1266 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, cycles);
1267 } while (read_seqcount_retry(&tk_core.seq, seq));
1268
1269 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1270 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1271
1272 /*
1273 * Interpolate if necessary, adjusting back from the start of the
1274 * current interval
1275 */
1276 if (do_interp) {
1277 u64 partial_history_cycles, total_history_cycles;
1278 bool discontinuity;
1279
1280 /*
1281 * Check that the counter value is not before the provided
1282 * history reference and that the history doesn't cross a
1283 * clocksource change
1284 */
1285 if (!history_begin ||
1286 !timestamp_in_interval(history_begin->cycles,
1287 cycles, system_counterval.cycles) ||
1288 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1289 return -EINVAL;
1290 partial_history_cycles = cycles - system_counterval.cycles;
1291 total_history_cycles = cycles - history_begin->cycles;
1292 discontinuity =
1293 history_begin->clock_was_set_seq != clock_was_set_seq;
1294
1295 ret = adjust_historical_crosststamp(history_begin,
1296 partial_history_cycles,
1297 total_history_cycles,
1298 discontinuity, xtstamp);
1299 if (ret)
1300 return ret;
1301 }
1302
1303 return 0;
1304}
1305EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1306
1307/**
1308 * do_settimeofday64 - Sets the time of day.
1309 * @ts: pointer to the timespec64 variable containing the new time
1310 *
1311 * Sets the time of day to the new time and update NTP and notify hrtimers
1312 */
1313int do_settimeofday64(const struct timespec64 *ts)
1314{
1315 struct timekeeper *tk = &tk_core.timekeeper;
1316 struct timespec64 ts_delta, xt;
1317 unsigned long flags;
1318 int ret = 0;
1319
1320 if (!timespec64_valid_settod(ts))
1321 return -EINVAL;
1322
1323 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1324 write_seqcount_begin(&tk_core.seq);
1325
1326 timekeeping_forward_now(tk);
1327
1328 xt = tk_xtime(tk);
1329 ts_delta = timespec64_sub(*ts, xt);
1330
1331 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1332 ret = -EINVAL;
1333 goto out;
1334 }
1335
1336 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1337
1338 tk_set_xtime(tk, ts);
1339out:
1340 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1341
1342 write_seqcount_end(&tk_core.seq);
1343 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1344
1345 /* Signal hrtimers about time change */
1346 clock_was_set(CLOCK_SET_WALL);
1347
1348 if (!ret) {
1349 audit_tk_injoffset(ts_delta);
1350 add_device_randomness(ts, sizeof(*ts));
1351 }
1352
1353 return ret;
1354}
1355EXPORT_SYMBOL(do_settimeofday64);
1356
1357/**
1358 * timekeeping_inject_offset - Adds or subtracts from the current time.
1359 * @ts: Pointer to the timespec variable containing the offset
1360 *
1361 * Adds or subtracts an offset value from the current time.
1362 */
1363static int timekeeping_inject_offset(const struct timespec64 *ts)
1364{
1365 struct timekeeper *tk = &tk_core.timekeeper;
1366 unsigned long flags;
1367 struct timespec64 tmp;
1368 int ret = 0;
1369
1370 if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1371 return -EINVAL;
1372
1373 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1374 write_seqcount_begin(&tk_core.seq);
1375
1376 timekeeping_forward_now(tk);
1377
1378 /* Make sure the proposed value is valid */
1379 tmp = timespec64_add(tk_xtime(tk), *ts);
1380 if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1381 !timespec64_valid_settod(&tmp)) {
1382 ret = -EINVAL;
1383 goto error;
1384 }
1385
1386 tk_xtime_add(tk, ts);
1387 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1388
1389error: /* even if we error out, we forwarded the time, so call update */
1390 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1391
1392 write_seqcount_end(&tk_core.seq);
1393 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1394
1395 /* Signal hrtimers about time change */
1396 clock_was_set(CLOCK_SET_WALL);
1397
1398 return ret;
1399}
1400
1401/*
1402 * Indicates if there is an offset between the system clock and the hardware
1403 * clock/persistent clock/rtc.
1404 */
1405int persistent_clock_is_local;
1406
1407/*
1408 * Adjust the time obtained from the CMOS to be UTC time instead of
1409 * local time.
1410 *
1411 * This is ugly, but preferable to the alternatives. Otherwise we
1412 * would either need to write a program to do it in /etc/rc (and risk
1413 * confusion if the program gets run more than once; it would also be
1414 * hard to make the program warp the clock precisely n hours) or
1415 * compile in the timezone information into the kernel. Bad, bad....
1416 *
1417 * - TYT, 1992-01-01
1418 *
1419 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1420 * as real UNIX machines always do it. This avoids all headaches about
1421 * daylight saving times and warping kernel clocks.
1422 */
1423void timekeeping_warp_clock(void)
1424{
1425 if (sys_tz.tz_minuteswest != 0) {
1426 struct timespec64 adjust;
1427
1428 persistent_clock_is_local = 1;
1429 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1430 adjust.tv_nsec = 0;
1431 timekeeping_inject_offset(&adjust);
1432 }
1433}
1434
1435/*
1436 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1437 */
1438static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1439{
1440 tk->tai_offset = tai_offset;
1441 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1442}
1443
1444/*
1445 * change_clocksource - Swaps clocksources if a new one is available
1446 *
1447 * Accumulates current time interval and initializes new clocksource
1448 */
1449static int change_clocksource(void *data)
1450{
1451 struct timekeeper *tk = &tk_core.timekeeper;
1452 struct clocksource *new, *old = NULL;
1453 unsigned long flags;
1454 bool change = false;
1455
1456 new = (struct clocksource *) data;
1457
1458 /*
1459 * If the cs is in module, get a module reference. Succeeds
1460 * for built-in code (owner == NULL) as well.
1461 */
1462 if (try_module_get(new->owner)) {
1463 if (!new->enable || new->enable(new) == 0)
1464 change = true;
1465 else
1466 module_put(new->owner);
1467 }
1468
1469 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1470 write_seqcount_begin(&tk_core.seq);
1471
1472 timekeeping_forward_now(tk);
1473
1474 if (change) {
1475 old = tk->tkr_mono.clock;
1476 tk_setup_internals(tk, new);
1477 }
1478
1479 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1480
1481 write_seqcount_end(&tk_core.seq);
1482 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1483
1484 if (old) {
1485 if (old->disable)
1486 old->disable(old);
1487
1488 module_put(old->owner);
1489 }
1490
1491 return 0;
1492}
1493
1494/**
1495 * timekeeping_notify - Install a new clock source
1496 * @clock: pointer to the clock source
1497 *
1498 * This function is called from clocksource.c after a new, better clock
1499 * source has been registered. The caller holds the clocksource_mutex.
1500 */
1501int timekeeping_notify(struct clocksource *clock)
1502{
1503 struct timekeeper *tk = &tk_core.timekeeper;
1504
1505 if (tk->tkr_mono.clock == clock)
1506 return 0;
1507 stop_machine(change_clocksource, clock, NULL);
1508 tick_clock_notify();
1509 return tk->tkr_mono.clock == clock ? 0 : -1;
1510}
1511
1512/**
1513 * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1514 * @ts: pointer to the timespec64 to be set
1515 *
1516 * Returns the raw monotonic time (completely un-modified by ntp)
1517 */
1518void ktime_get_raw_ts64(struct timespec64 *ts)
1519{
1520 struct timekeeper *tk = &tk_core.timekeeper;
1521 unsigned int seq;
1522 u64 nsecs;
1523
1524 do {
1525 seq = read_seqcount_begin(&tk_core.seq);
1526 ts->tv_sec = tk->raw_sec;
1527 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1528
1529 } while (read_seqcount_retry(&tk_core.seq, seq));
1530
1531 ts->tv_nsec = 0;
1532 timespec64_add_ns(ts, nsecs);
1533}
1534EXPORT_SYMBOL(ktime_get_raw_ts64);
1535
1536
1537/**
1538 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1539 */
1540int timekeeping_valid_for_hres(void)
1541{
1542 struct timekeeper *tk = &tk_core.timekeeper;
1543 unsigned int seq;
1544 int ret;
1545
1546 do {
1547 seq = read_seqcount_begin(&tk_core.seq);
1548
1549 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1550
1551 } while (read_seqcount_retry(&tk_core.seq, seq));
1552
1553 return ret;
1554}
1555
1556/**
1557 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1558 */
1559u64 timekeeping_max_deferment(void)
1560{
1561 struct timekeeper *tk = &tk_core.timekeeper;
1562 unsigned int seq;
1563 u64 ret;
1564
1565 do {
1566 seq = read_seqcount_begin(&tk_core.seq);
1567
1568 ret = tk->tkr_mono.clock->max_idle_ns;
1569
1570 } while (read_seqcount_retry(&tk_core.seq, seq));
1571
1572 return ret;
1573}
1574
1575/**
1576 * read_persistent_clock64 - Return time from the persistent clock.
1577 * @ts: Pointer to the storage for the readout value
1578 *
1579 * Weak dummy function for arches that do not yet support it.
1580 * Reads the time from the battery backed persistent clock.
1581 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1582 *
1583 * XXX - Do be sure to remove it once all arches implement it.
1584 */
1585void __weak read_persistent_clock64(struct timespec64 *ts)
1586{
1587 ts->tv_sec = 0;
1588 ts->tv_nsec = 0;
1589}
1590
1591/**
1592 * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1593 * from the boot.
1594 * @wall_time: current time as returned by persistent clock
1595 * @boot_offset: offset that is defined as wall_time - boot_time
1596 *
1597 * Weak dummy function for arches that do not yet support it.
1598 *
1599 * The default function calculates offset based on the current value of
1600 * local_clock(). This way architectures that support sched_clock() but don't
1601 * support dedicated boot time clock will provide the best estimate of the
1602 * boot time.
1603 */
1604void __weak __init
1605read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1606 struct timespec64 *boot_offset)
1607{
1608 read_persistent_clock64(wall_time);
1609 *boot_offset = ns_to_timespec64(local_clock());
1610}
1611
1612/*
1613 * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1614 *
1615 * The flag starts of false and is only set when a suspend reaches
1616 * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1617 * timekeeper clocksource is not stopping across suspend and has been
1618 * used to update sleep time. If the timekeeper clocksource has stopped
1619 * then the flag stays true and is used by the RTC resume code to decide
1620 * whether sleeptime must be injected and if so the flag gets false then.
1621 *
1622 * If a suspend fails before reaching timekeeping_resume() then the flag
1623 * stays false and prevents erroneous sleeptime injection.
1624 */
1625static bool suspend_timing_needed;
1626
1627/* Flag for if there is a persistent clock on this platform */
1628static bool persistent_clock_exists;
1629
1630/*
1631 * timekeeping_init - Initializes the clocksource and common timekeeping values
1632 */
1633void __init timekeeping_init(void)
1634{
1635 struct timespec64 wall_time, boot_offset, wall_to_mono;
1636 struct timekeeper *tk = &tk_core.timekeeper;
1637 struct clocksource *clock;
1638 unsigned long flags;
1639
1640 read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1641 if (timespec64_valid_settod(&wall_time) &&
1642 timespec64_to_ns(&wall_time) > 0) {
1643 persistent_clock_exists = true;
1644 } else if (timespec64_to_ns(&wall_time) != 0) {
1645 pr_warn("Persistent clock returned invalid value");
1646 wall_time = (struct timespec64){0};
1647 }
1648
1649 if (timespec64_compare(&wall_time, &boot_offset) < 0)
1650 boot_offset = (struct timespec64){0};
1651
1652 /*
1653 * We want set wall_to_mono, so the following is true:
1654 * wall time + wall_to_mono = boot time
1655 */
1656 wall_to_mono = timespec64_sub(boot_offset, wall_time);
1657
1658 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1659 write_seqcount_begin(&tk_core.seq);
1660 ntp_init();
1661
1662 clock = clocksource_default_clock();
1663 if (clock->enable)
1664 clock->enable(clock);
1665 tk_setup_internals(tk, clock);
1666
1667 tk_set_xtime(tk, &wall_time);
1668 tk->raw_sec = 0;
1669
1670 tk_set_wall_to_mono(tk, wall_to_mono);
1671
1672 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1673
1674 write_seqcount_end(&tk_core.seq);
1675 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1676}
1677
1678/* time in seconds when suspend began for persistent clock */
1679static struct timespec64 timekeeping_suspend_time;
1680
1681/**
1682 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1683 * @tk: Pointer to the timekeeper to be updated
1684 * @delta: Pointer to the delta value in timespec64 format
1685 *
1686 * Takes a timespec offset measuring a suspend interval and properly
1687 * adds the sleep offset to the timekeeping variables.
1688 */
1689static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1690 const struct timespec64 *delta)
1691{
1692 if (!timespec64_valid_strict(delta)) {
1693 printk_deferred(KERN_WARNING
1694 "__timekeeping_inject_sleeptime: Invalid "
1695 "sleep delta value!\n");
1696 return;
1697 }
1698 tk_xtime_add(tk, delta);
1699 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1700 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1701 tk_debug_account_sleep_time(delta);
1702}
1703
1704#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1705/*
1706 * We have three kinds of time sources to use for sleep time
1707 * injection, the preference order is:
1708 * 1) non-stop clocksource
1709 * 2) persistent clock (ie: RTC accessible when irqs are off)
1710 * 3) RTC
1711 *
1712 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1713 * If system has neither 1) nor 2), 3) will be used finally.
1714 *
1715 *
1716 * If timekeeping has injected sleeptime via either 1) or 2),
1717 * 3) becomes needless, so in this case we don't need to call
1718 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1719 * means.
1720 */
1721bool timekeeping_rtc_skipresume(void)
1722{
1723 return !suspend_timing_needed;
1724}
1725
1726/*
1727 * 1) can be determined whether to use or not only when doing
1728 * timekeeping_resume() which is invoked after rtc_suspend(),
1729 * so we can't skip rtc_suspend() surely if system has 1).
1730 *
1731 * But if system has 2), 2) will definitely be used, so in this
1732 * case we don't need to call rtc_suspend(), and this is what
1733 * timekeeping_rtc_skipsuspend() means.
1734 */
1735bool timekeeping_rtc_skipsuspend(void)
1736{
1737 return persistent_clock_exists;
1738}
1739
1740/**
1741 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1742 * @delta: pointer to a timespec64 delta value
1743 *
1744 * This hook is for architectures that cannot support read_persistent_clock64
1745 * because their RTC/persistent clock is only accessible when irqs are enabled.
1746 * and also don't have an effective nonstop clocksource.
1747 *
1748 * This function should only be called by rtc_resume(), and allows
1749 * a suspend offset to be injected into the timekeeping values.
1750 */
1751void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1752{
1753 struct timekeeper *tk = &tk_core.timekeeper;
1754 unsigned long flags;
1755
1756 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1757 write_seqcount_begin(&tk_core.seq);
1758
1759 suspend_timing_needed = false;
1760
1761 timekeeping_forward_now(tk);
1762
1763 __timekeeping_inject_sleeptime(tk, delta);
1764
1765 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1766
1767 write_seqcount_end(&tk_core.seq);
1768 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1769
1770 /* Signal hrtimers about time change */
1771 clock_was_set(CLOCK_SET_WALL | CLOCK_SET_BOOT);
1772}
1773#endif
1774
1775/**
1776 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1777 */
1778void timekeeping_resume(void)
1779{
1780 struct timekeeper *tk = &tk_core.timekeeper;
1781 struct clocksource *clock = tk->tkr_mono.clock;
1782 unsigned long flags;
1783 struct timespec64 ts_new, ts_delta;
1784 u64 cycle_now, nsec;
1785 bool inject_sleeptime = false;
1786
1787 read_persistent_clock64(&ts_new);
1788
1789 clockevents_resume();
1790 clocksource_resume();
1791
1792 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1793 write_seqcount_begin(&tk_core.seq);
1794
1795 /*
1796 * After system resumes, we need to calculate the suspended time and
1797 * compensate it for the OS time. There are 3 sources that could be
1798 * used: Nonstop clocksource during suspend, persistent clock and rtc
1799 * device.
1800 *
1801 * One specific platform may have 1 or 2 or all of them, and the
1802 * preference will be:
1803 * suspend-nonstop clocksource -> persistent clock -> rtc
1804 * The less preferred source will only be tried if there is no better
1805 * usable source. The rtc part is handled separately in rtc core code.
1806 */
1807 cycle_now = tk_clock_read(&tk->tkr_mono);
1808 nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1809 if (nsec > 0) {
1810 ts_delta = ns_to_timespec64(nsec);
1811 inject_sleeptime = true;
1812 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1813 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1814 inject_sleeptime = true;
1815 }
1816
1817 if (inject_sleeptime) {
1818 suspend_timing_needed = false;
1819 __timekeeping_inject_sleeptime(tk, &ts_delta);
1820 }
1821
1822 /* Re-base the last cycle value */
1823 tk->tkr_mono.cycle_last = cycle_now;
1824 tk->tkr_raw.cycle_last = cycle_now;
1825
1826 tk->ntp_error = 0;
1827 timekeeping_suspended = 0;
1828 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1829 write_seqcount_end(&tk_core.seq);
1830 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1831
1832 touch_softlockup_watchdog();
1833
1834 /* Resume the clockevent device(s) and hrtimers */
1835 tick_resume();
1836 /* Notify timerfd as resume is equivalent to clock_was_set() */
1837 timerfd_resume();
1838}
1839
1840int timekeeping_suspend(void)
1841{
1842 struct timekeeper *tk = &tk_core.timekeeper;
1843 unsigned long flags;
1844 struct timespec64 delta, delta_delta;
1845 static struct timespec64 old_delta;
1846 struct clocksource *curr_clock;
1847 u64 cycle_now;
1848
1849 read_persistent_clock64(&timekeeping_suspend_time);
1850
1851 /*
1852 * On some systems the persistent_clock can not be detected at
1853 * timekeeping_init by its return value, so if we see a valid
1854 * value returned, update the persistent_clock_exists flag.
1855 */
1856 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1857 persistent_clock_exists = true;
1858
1859 suspend_timing_needed = true;
1860
1861 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1862 write_seqcount_begin(&tk_core.seq);
1863 timekeeping_forward_now(tk);
1864 timekeeping_suspended = 1;
1865
1866 /*
1867 * Since we've called forward_now, cycle_last stores the value
1868 * just read from the current clocksource. Save this to potentially
1869 * use in suspend timing.
1870 */
1871 curr_clock = tk->tkr_mono.clock;
1872 cycle_now = tk->tkr_mono.cycle_last;
1873 clocksource_start_suspend_timing(curr_clock, cycle_now);
1874
1875 if (persistent_clock_exists) {
1876 /*
1877 * To avoid drift caused by repeated suspend/resumes,
1878 * which each can add ~1 second drift error,
1879 * try to compensate so the difference in system time
1880 * and persistent_clock time stays close to constant.
1881 */
1882 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1883 delta_delta = timespec64_sub(delta, old_delta);
1884 if (abs(delta_delta.tv_sec) >= 2) {
1885 /*
1886 * if delta_delta is too large, assume time correction
1887 * has occurred and set old_delta to the current delta.
1888 */
1889 old_delta = delta;
1890 } else {
1891 /* Otherwise try to adjust old_system to compensate */
1892 timekeeping_suspend_time =
1893 timespec64_add(timekeeping_suspend_time, delta_delta);
1894 }
1895 }
1896
1897 timekeeping_update(tk, TK_MIRROR);
1898 halt_fast_timekeeper(tk);
1899 write_seqcount_end(&tk_core.seq);
1900 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1901
1902 tick_suspend();
1903 clocksource_suspend();
1904 clockevents_suspend();
1905
1906 return 0;
1907}
1908
1909/* sysfs resume/suspend bits for timekeeping */
1910static struct syscore_ops timekeeping_syscore_ops = {
1911 .resume = timekeeping_resume,
1912 .suspend = timekeeping_suspend,
1913};
1914
1915static int __init timekeeping_init_ops(void)
1916{
1917 register_syscore_ops(&timekeeping_syscore_ops);
1918 return 0;
1919}
1920device_initcall(timekeeping_init_ops);
1921
1922/*
1923 * Apply a multiplier adjustment to the timekeeper
1924 */
1925static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1926 s64 offset,
1927 s32 mult_adj)
1928{
1929 s64 interval = tk->cycle_interval;
1930
1931 if (mult_adj == 0) {
1932 return;
1933 } else if (mult_adj == -1) {
1934 interval = -interval;
1935 offset = -offset;
1936 } else if (mult_adj != 1) {
1937 interval *= mult_adj;
1938 offset *= mult_adj;
1939 }
1940
1941 /*
1942 * So the following can be confusing.
1943 *
1944 * To keep things simple, lets assume mult_adj == 1 for now.
1945 *
1946 * When mult_adj != 1, remember that the interval and offset values
1947 * have been appropriately scaled so the math is the same.
1948 *
1949 * The basic idea here is that we're increasing the multiplier
1950 * by one, this causes the xtime_interval to be incremented by
1951 * one cycle_interval. This is because:
1952 * xtime_interval = cycle_interval * mult
1953 * So if mult is being incremented by one:
1954 * xtime_interval = cycle_interval * (mult + 1)
1955 * Its the same as:
1956 * xtime_interval = (cycle_interval * mult) + cycle_interval
1957 * Which can be shortened to:
1958 * xtime_interval += cycle_interval
1959 *
1960 * So offset stores the non-accumulated cycles. Thus the current
1961 * time (in shifted nanoseconds) is:
1962 * now = (offset * adj) + xtime_nsec
1963 * Now, even though we're adjusting the clock frequency, we have
1964 * to keep time consistent. In other words, we can't jump back
1965 * in time, and we also want to avoid jumping forward in time.
1966 *
1967 * So given the same offset value, we need the time to be the same
1968 * both before and after the freq adjustment.
1969 * now = (offset * adj_1) + xtime_nsec_1
1970 * now = (offset * adj_2) + xtime_nsec_2
1971 * So:
1972 * (offset * adj_1) + xtime_nsec_1 =
1973 * (offset * adj_2) + xtime_nsec_2
1974 * And we know:
1975 * adj_2 = adj_1 + 1
1976 * So:
1977 * (offset * adj_1) + xtime_nsec_1 =
1978 * (offset * (adj_1+1)) + xtime_nsec_2
1979 * (offset * adj_1) + xtime_nsec_1 =
1980 * (offset * adj_1) + offset + xtime_nsec_2
1981 * Canceling the sides:
1982 * xtime_nsec_1 = offset + xtime_nsec_2
1983 * Which gives us:
1984 * xtime_nsec_2 = xtime_nsec_1 - offset
1985 * Which simplifies to:
1986 * xtime_nsec -= offset
1987 */
1988 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1989 /* NTP adjustment caused clocksource mult overflow */
1990 WARN_ON_ONCE(1);
1991 return;
1992 }
1993
1994 tk->tkr_mono.mult += mult_adj;
1995 tk->xtime_interval += interval;
1996 tk->tkr_mono.xtime_nsec -= offset;
1997}
1998
1999/*
2000 * Adjust the timekeeper's multiplier to the correct frequency
2001 * and also to reduce the accumulated error value.
2002 */
2003static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
2004{
2005 u32 mult;
2006
2007 /*
2008 * Determine the multiplier from the current NTP tick length.
2009 * Avoid expensive division when the tick length doesn't change.
2010 */
2011 if (likely(tk->ntp_tick == ntp_tick_length())) {
2012 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
2013 } else {
2014 tk->ntp_tick = ntp_tick_length();
2015 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
2016 tk->xtime_remainder, tk->cycle_interval);
2017 }
2018
2019 /*
2020 * If the clock is behind the NTP time, increase the multiplier by 1
2021 * to catch up with it. If it's ahead and there was a remainder in the
2022 * tick division, the clock will slow down. Otherwise it will stay
2023 * ahead until the tick length changes to a non-divisible value.
2024 */
2025 tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
2026 mult += tk->ntp_err_mult;
2027
2028 timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
2029
2030 if (unlikely(tk->tkr_mono.clock->maxadj &&
2031 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
2032 > tk->tkr_mono.clock->maxadj))) {
2033 printk_once(KERN_WARNING
2034 "Adjusting %s more than 11%% (%ld vs %ld)\n",
2035 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
2036 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
2037 }
2038
2039 /*
2040 * It may be possible that when we entered this function, xtime_nsec
2041 * was very small. Further, if we're slightly speeding the clocksource
2042 * in the code above, its possible the required corrective factor to
2043 * xtime_nsec could cause it to underflow.
2044 *
2045 * Now, since we have already accumulated the second and the NTP
2046 * subsystem has been notified via second_overflow(), we need to skip
2047 * the next update.
2048 */
2049 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
2050 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
2051 tk->tkr_mono.shift;
2052 tk->xtime_sec--;
2053 tk->skip_second_overflow = 1;
2054 }
2055}
2056
2057/*
2058 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
2059 *
2060 * Helper function that accumulates the nsecs greater than a second
2061 * from the xtime_nsec field to the xtime_secs field.
2062 * It also calls into the NTP code to handle leapsecond processing.
2063 */
2064static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
2065{
2066 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
2067 unsigned int clock_set = 0;
2068
2069 while (tk->tkr_mono.xtime_nsec >= nsecps) {
2070 int leap;
2071
2072 tk->tkr_mono.xtime_nsec -= nsecps;
2073 tk->xtime_sec++;
2074
2075 /*
2076 * Skip NTP update if this second was accumulated before,
2077 * i.e. xtime_nsec underflowed in timekeeping_adjust()
2078 */
2079 if (unlikely(tk->skip_second_overflow)) {
2080 tk->skip_second_overflow = 0;
2081 continue;
2082 }
2083
2084 /* Figure out if its a leap sec and apply if needed */
2085 leap = second_overflow(tk->xtime_sec);
2086 if (unlikely(leap)) {
2087 struct timespec64 ts;
2088
2089 tk->xtime_sec += leap;
2090
2091 ts.tv_sec = leap;
2092 ts.tv_nsec = 0;
2093 tk_set_wall_to_mono(tk,
2094 timespec64_sub(tk->wall_to_monotonic, ts));
2095
2096 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
2097
2098 clock_set = TK_CLOCK_WAS_SET;
2099 }
2100 }
2101 return clock_set;
2102}
2103
2104/*
2105 * logarithmic_accumulation - shifted accumulation of cycles
2106 *
2107 * This functions accumulates a shifted interval of cycles into
2108 * a shifted interval nanoseconds. Allows for O(log) accumulation
2109 * loop.
2110 *
2111 * Returns the unconsumed cycles.
2112 */
2113static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2114 u32 shift, unsigned int *clock_set)
2115{
2116 u64 interval = tk->cycle_interval << shift;
2117 u64 snsec_per_sec;
2118
2119 /* If the offset is smaller than a shifted interval, do nothing */
2120 if (offset < interval)
2121 return offset;
2122
2123 /* Accumulate one shifted interval */
2124 offset -= interval;
2125 tk->tkr_mono.cycle_last += interval;
2126 tk->tkr_raw.cycle_last += interval;
2127
2128 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2129 *clock_set |= accumulate_nsecs_to_secs(tk);
2130
2131 /* Accumulate raw time */
2132 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2133 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2134 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2135 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2136 tk->raw_sec++;
2137 }
2138
2139 /* Accumulate error between NTP and clock interval */
2140 tk->ntp_error += tk->ntp_tick << shift;
2141 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2142 (tk->ntp_error_shift + shift);
2143
2144 return offset;
2145}
2146
2147/*
2148 * timekeeping_advance - Updates the timekeeper to the current time and
2149 * current NTP tick length
2150 */
2151static bool timekeeping_advance(enum timekeeping_adv_mode mode)
2152{
2153 struct timekeeper *real_tk = &tk_core.timekeeper;
2154 struct timekeeper *tk = &shadow_timekeeper;
2155 u64 offset;
2156 int shift = 0, maxshift;
2157 unsigned int clock_set = 0;
2158 unsigned long flags;
2159
2160 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2161
2162 /* Make sure we're fully resumed: */
2163 if (unlikely(timekeeping_suspended))
2164 goto out;
2165
2166 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2167 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2168
2169 /* Check if there's really nothing to do */
2170 if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2171 goto out;
2172
2173 /* Do some additional sanity checking */
2174 timekeeping_check_update(tk, offset);
2175
2176 /*
2177 * With NO_HZ we may have to accumulate many cycle_intervals
2178 * (think "ticks") worth of time at once. To do this efficiently,
2179 * we calculate the largest doubling multiple of cycle_intervals
2180 * that is smaller than the offset. We then accumulate that
2181 * chunk in one go, and then try to consume the next smaller
2182 * doubled multiple.
2183 */
2184 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2185 shift = max(0, shift);
2186 /* Bound shift to one less than what overflows tick_length */
2187 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2188 shift = min(shift, maxshift);
2189 while (offset >= tk->cycle_interval) {
2190 offset = logarithmic_accumulation(tk, offset, shift,
2191 &clock_set);
2192 if (offset < tk->cycle_interval<<shift)
2193 shift--;
2194 }
2195
2196 /* Adjust the multiplier to correct NTP error */
2197 timekeeping_adjust(tk, offset);
2198
2199 /*
2200 * Finally, make sure that after the rounding
2201 * xtime_nsec isn't larger than NSEC_PER_SEC
2202 */
2203 clock_set |= accumulate_nsecs_to_secs(tk);
2204
2205 write_seqcount_begin(&tk_core.seq);
2206 /*
2207 * Update the real timekeeper.
2208 *
2209 * We could avoid this memcpy by switching pointers, but that
2210 * requires changes to all other timekeeper usage sites as
2211 * well, i.e. move the timekeeper pointer getter into the
2212 * spinlocked/seqcount protected sections. And we trade this
2213 * memcpy under the tk_core.seq against one before we start
2214 * updating.
2215 */
2216 timekeeping_update(tk, clock_set);
2217 memcpy(real_tk, tk, sizeof(*tk));
2218 /* The memcpy must come last. Do not put anything here! */
2219 write_seqcount_end(&tk_core.seq);
2220out:
2221 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2222
2223 return !!clock_set;
2224}
2225
2226/**
2227 * update_wall_time - Uses the current clocksource to increment the wall time
2228 *
2229 */
2230void update_wall_time(void)
2231{
2232 if (timekeeping_advance(TK_ADV_TICK))
2233 clock_was_set_delayed();
2234}
2235
2236/**
2237 * getboottime64 - Return the real time of system boot.
2238 * @ts: pointer to the timespec64 to be set
2239 *
2240 * Returns the wall-time of boot in a timespec64.
2241 *
2242 * This is based on the wall_to_monotonic offset and the total suspend
2243 * time. Calls to settimeofday will affect the value returned (which
2244 * basically means that however wrong your real time clock is at boot time,
2245 * you get the right time here).
2246 */
2247void getboottime64(struct timespec64 *ts)
2248{
2249 struct timekeeper *tk = &tk_core.timekeeper;
2250 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2251
2252 *ts = ktime_to_timespec64(t);
2253}
2254EXPORT_SYMBOL_GPL(getboottime64);
2255
2256void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2257{
2258 struct timekeeper *tk = &tk_core.timekeeper;
2259 unsigned int seq;
2260
2261 do {
2262 seq = read_seqcount_begin(&tk_core.seq);
2263
2264 *ts = tk_xtime(tk);
2265 } while (read_seqcount_retry(&tk_core.seq, seq));
2266}
2267EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2268
2269void ktime_get_coarse_ts64(struct timespec64 *ts)
2270{
2271 struct timekeeper *tk = &tk_core.timekeeper;
2272 struct timespec64 now, mono;
2273 unsigned int seq;
2274
2275 do {
2276 seq = read_seqcount_begin(&tk_core.seq);
2277
2278 now = tk_xtime(tk);
2279 mono = tk->wall_to_monotonic;
2280 } while (read_seqcount_retry(&tk_core.seq, seq));
2281
2282 set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2283 now.tv_nsec + mono.tv_nsec);
2284}
2285EXPORT_SYMBOL(ktime_get_coarse_ts64);
2286
2287/*
2288 * Must hold jiffies_lock
2289 */
2290void do_timer(unsigned long ticks)
2291{
2292 jiffies_64 += ticks;
2293 calc_global_load();
2294}
2295
2296/**
2297 * ktime_get_update_offsets_now - hrtimer helper
2298 * @cwsseq: pointer to check and store the clock was set sequence number
2299 * @offs_real: pointer to storage for monotonic -> realtime offset
2300 * @offs_boot: pointer to storage for monotonic -> boottime offset
2301 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2302 *
2303 * Returns current monotonic time and updates the offsets if the
2304 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2305 * different.
2306 *
2307 * Called from hrtimer_interrupt() or retrigger_next_event()
2308 */
2309ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2310 ktime_t *offs_boot, ktime_t *offs_tai)
2311{
2312 struct timekeeper *tk = &tk_core.timekeeper;
2313 unsigned int seq;
2314 ktime_t base;
2315 u64 nsecs;
2316
2317 do {
2318 seq = read_seqcount_begin(&tk_core.seq);
2319
2320 base = tk->tkr_mono.base;
2321 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2322 base = ktime_add_ns(base, nsecs);
2323
2324 if (*cwsseq != tk->clock_was_set_seq) {
2325 *cwsseq = tk->clock_was_set_seq;
2326 *offs_real = tk->offs_real;
2327 *offs_boot = tk->offs_boot;
2328 *offs_tai = tk->offs_tai;
2329 }
2330
2331 /* Handle leapsecond insertion adjustments */
2332 if (unlikely(base >= tk->next_leap_ktime))
2333 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2334
2335 } while (read_seqcount_retry(&tk_core.seq, seq));
2336
2337 return base;
2338}
2339
2340/*
2341 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2342 */
2343static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2344{
2345 if (txc->modes & ADJ_ADJTIME) {
2346 /* singleshot must not be used with any other mode bits */
2347 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2348 return -EINVAL;
2349 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2350 !capable(CAP_SYS_TIME))
2351 return -EPERM;
2352 } else {
2353 /* In order to modify anything, you gotta be super-user! */
2354 if (txc->modes && !capable(CAP_SYS_TIME))
2355 return -EPERM;
2356 /*
2357 * if the quartz is off by more than 10% then
2358 * something is VERY wrong!
2359 */
2360 if (txc->modes & ADJ_TICK &&
2361 (txc->tick < 900000/USER_HZ ||
2362 txc->tick > 1100000/USER_HZ))
2363 return -EINVAL;
2364 }
2365
2366 if (txc->modes & ADJ_SETOFFSET) {
2367 /* In order to inject time, you gotta be super-user! */
2368 if (!capable(CAP_SYS_TIME))
2369 return -EPERM;
2370
2371 /*
2372 * Validate if a timespec/timeval used to inject a time
2373 * offset is valid. Offsets can be positive or negative, so
2374 * we don't check tv_sec. The value of the timeval/timespec
2375 * is the sum of its fields,but *NOTE*:
2376 * The field tv_usec/tv_nsec must always be non-negative and
2377 * we can't have more nanoseconds/microseconds than a second.
2378 */
2379 if (txc->time.tv_usec < 0)
2380 return -EINVAL;
2381
2382 if (txc->modes & ADJ_NANO) {
2383 if (txc->time.tv_usec >= NSEC_PER_SEC)
2384 return -EINVAL;
2385 } else {
2386 if (txc->time.tv_usec >= USEC_PER_SEC)
2387 return -EINVAL;
2388 }
2389 }
2390
2391 /*
2392 * Check for potential multiplication overflows that can
2393 * only happen on 64-bit systems:
2394 */
2395 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2396 if (LLONG_MIN / PPM_SCALE > txc->freq)
2397 return -EINVAL;
2398 if (LLONG_MAX / PPM_SCALE < txc->freq)
2399 return -EINVAL;
2400 }
2401
2402 return 0;
2403}
2404
2405/**
2406 * random_get_entropy_fallback - Returns the raw clock source value,
2407 * used by random.c for platforms with no valid random_get_entropy().
2408 */
2409unsigned long random_get_entropy_fallback(void)
2410{
2411 struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono;
2412 struct clocksource *clock = READ_ONCE(tkr->clock);
2413
2414 if (unlikely(timekeeping_suspended || !clock))
2415 return 0;
2416 return clock->read(clock);
2417}
2418EXPORT_SYMBOL_GPL(random_get_entropy_fallback);
2419
2420/**
2421 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2422 */
2423int do_adjtimex(struct __kernel_timex *txc)
2424{
2425 struct timekeeper *tk = &tk_core.timekeeper;
2426 struct audit_ntp_data ad;
2427 bool clock_set = false;
2428 struct timespec64 ts;
2429 unsigned long flags;
2430 s32 orig_tai, tai;
2431 int ret;
2432
2433 /* Validate the data before disabling interrupts */
2434 ret = timekeeping_validate_timex(txc);
2435 if (ret)
2436 return ret;
2437 add_device_randomness(txc, sizeof(*txc));
2438
2439 if (txc->modes & ADJ_SETOFFSET) {
2440 struct timespec64 delta;
2441 delta.tv_sec = txc->time.tv_sec;
2442 delta.tv_nsec = txc->time.tv_usec;
2443 if (!(txc->modes & ADJ_NANO))
2444 delta.tv_nsec *= 1000;
2445 ret = timekeeping_inject_offset(&delta);
2446 if (ret)
2447 return ret;
2448
2449 audit_tk_injoffset(delta);
2450 }
2451
2452 audit_ntp_init(&ad);
2453
2454 ktime_get_real_ts64(&ts);
2455 add_device_randomness(&ts, sizeof(ts));
2456
2457 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2458 write_seqcount_begin(&tk_core.seq);
2459
2460 orig_tai = tai = tk->tai_offset;
2461 ret = __do_adjtimex(txc, &ts, &tai, &ad);
2462
2463 if (tai != orig_tai) {
2464 __timekeeping_set_tai_offset(tk, tai);
2465 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2466 clock_set = true;
2467 }
2468 tk_update_leap_state(tk);
2469
2470 write_seqcount_end(&tk_core.seq);
2471 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2472
2473 audit_ntp_log(&ad);
2474
2475 /* Update the multiplier immediately if frequency was set directly */
2476 if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2477 clock_set |= timekeeping_advance(TK_ADV_FREQ);
2478
2479 if (clock_set)
2480 clock_was_set(CLOCK_REALTIME);
2481
2482 ntp_notify_cmos_timer();
2483
2484 return ret;
2485}
2486
2487#ifdef CONFIG_NTP_PPS
2488/**
2489 * hardpps() - Accessor function to NTP __hardpps function
2490 */
2491void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2492{
2493 unsigned long flags;
2494
2495 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2496 write_seqcount_begin(&tk_core.seq);
2497
2498 __hardpps(phase_ts, raw_ts);
2499
2500 write_seqcount_end(&tk_core.seq);
2501 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2502}
2503EXPORT_SYMBOL(hardpps);
2504#endif /* CONFIG_NTP_PPS */
1/*
2 * linux/kernel/time/timekeeping.c
3 *
4 * Kernel timekeeping code and accessor functions
5 *
6 * This code was moved from linux/kernel/timer.c.
7 * Please see that file for copyright and history logs.
8 *
9 */
10
11#include <linux/module.h>
12#include <linux/interrupt.h>
13#include <linux/percpu.h>
14#include <linux/init.h>
15#include <linux/mm.h>
16#include <linux/sched.h>
17#include <linux/syscore_ops.h>
18#include <linux/clocksource.h>
19#include <linux/jiffies.h>
20#include <linux/time.h>
21#include <linux/tick.h>
22#include <linux/stop_machine.h>
23
24/* Structure holding internal timekeeping values. */
25struct timekeeper {
26 /* Current clocksource used for timekeeping. */
27 struct clocksource *clock;
28 /* NTP adjusted clock multiplier */
29 u32 mult;
30 /* The shift value of the current clocksource. */
31 int shift;
32
33 /* Number of clock cycles in one NTP interval. */
34 cycle_t cycle_interval;
35 /* Number of clock shifted nano seconds in one NTP interval. */
36 u64 xtime_interval;
37 /* shifted nano seconds left over when rounding cycle_interval */
38 s64 xtime_remainder;
39 /* Raw nano seconds accumulated per NTP interval. */
40 u32 raw_interval;
41
42 /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
43 u64 xtime_nsec;
44 /* Difference between accumulated time and NTP time in ntp
45 * shifted nano seconds. */
46 s64 ntp_error;
47 /* Shift conversion between clock shifted nano seconds and
48 * ntp shifted nano seconds. */
49 int ntp_error_shift;
50
51 /* The current time */
52 struct timespec xtime;
53 /*
54 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
55 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
56 * at zero at system boot time, so wall_to_monotonic will be negative,
57 * however, we will ALWAYS keep the tv_nsec part positive so we can use
58 * the usual normalization.
59 *
60 * wall_to_monotonic is moved after resume from suspend for the
61 * monotonic time not to jump. We need to add total_sleep_time to
62 * wall_to_monotonic to get the real boot based time offset.
63 *
64 * - wall_to_monotonic is no longer the boot time, getboottime must be
65 * used instead.
66 */
67 struct timespec wall_to_monotonic;
68 /* time spent in suspend */
69 struct timespec total_sleep_time;
70 /* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
71 struct timespec raw_time;
72
73 /* Offset clock monotonic -> clock realtime */
74 ktime_t offs_real;
75
76 /* Offset clock monotonic -> clock boottime */
77 ktime_t offs_boot;
78
79 /* Seqlock for all timekeeper values */
80 seqlock_t lock;
81};
82
83static struct timekeeper timekeeper;
84
85/*
86 * This read-write spinlock protects us from races in SMP while
87 * playing with xtime.
88 */
89__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
90
91
92/* flag for if timekeeping is suspended */
93int __read_mostly timekeeping_suspended;
94
95
96
97/**
98 * timekeeper_setup_internals - Set up internals to use clocksource clock.
99 *
100 * @clock: Pointer to clocksource.
101 *
102 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
103 * pair and interval request.
104 *
105 * Unless you're the timekeeping code, you should not be using this!
106 */
107static void timekeeper_setup_internals(struct clocksource *clock)
108{
109 cycle_t interval;
110 u64 tmp, ntpinterval;
111
112 timekeeper.clock = clock;
113 clock->cycle_last = clock->read(clock);
114
115 /* Do the ns -> cycle conversion first, using original mult */
116 tmp = NTP_INTERVAL_LENGTH;
117 tmp <<= clock->shift;
118 ntpinterval = tmp;
119 tmp += clock->mult/2;
120 do_div(tmp, clock->mult);
121 if (tmp == 0)
122 tmp = 1;
123
124 interval = (cycle_t) tmp;
125 timekeeper.cycle_interval = interval;
126
127 /* Go back from cycles -> shifted ns */
128 timekeeper.xtime_interval = (u64) interval * clock->mult;
129 timekeeper.xtime_remainder = ntpinterval - timekeeper.xtime_interval;
130 timekeeper.raw_interval =
131 ((u64) interval * clock->mult) >> clock->shift;
132
133 timekeeper.xtime_nsec = 0;
134 timekeeper.shift = clock->shift;
135
136 timekeeper.ntp_error = 0;
137 timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
138
139 /*
140 * The timekeeper keeps its own mult values for the currently
141 * active clocksource. These value will be adjusted via NTP
142 * to counteract clock drifting.
143 */
144 timekeeper.mult = clock->mult;
145}
146
147/* Timekeeper helper functions. */
148static inline s64 timekeeping_get_ns(void)
149{
150 cycle_t cycle_now, cycle_delta;
151 struct clocksource *clock;
152
153 /* read clocksource: */
154 clock = timekeeper.clock;
155 cycle_now = clock->read(clock);
156
157 /* calculate the delta since the last update_wall_time: */
158 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
159
160 /* return delta convert to nanoseconds using ntp adjusted mult. */
161 return clocksource_cyc2ns(cycle_delta, timekeeper.mult,
162 timekeeper.shift);
163}
164
165static inline s64 timekeeping_get_ns_raw(void)
166{
167 cycle_t cycle_now, cycle_delta;
168 struct clocksource *clock;
169
170 /* read clocksource: */
171 clock = timekeeper.clock;
172 cycle_now = clock->read(clock);
173
174 /* calculate the delta since the last update_wall_time: */
175 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
176
177 /* return delta convert to nanoseconds. */
178 return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
179}
180
181static void update_rt_offset(void)
182{
183 struct timespec tmp, *wtm = &timekeeper.wall_to_monotonic;
184
185 set_normalized_timespec(&tmp, -wtm->tv_sec, -wtm->tv_nsec);
186 timekeeper.offs_real = timespec_to_ktime(tmp);
187}
188
189/* must hold write on timekeeper.lock */
190static void timekeeping_update(bool clearntp)
191{
192 if (clearntp) {
193 timekeeper.ntp_error = 0;
194 ntp_clear();
195 }
196 update_rt_offset();
197 update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
198 timekeeper.clock, timekeeper.mult);
199}
200
201
202/**
203 * timekeeping_forward_now - update clock to the current time
204 *
205 * Forward the current clock to update its state since the last call to
206 * update_wall_time(). This is useful before significant clock changes,
207 * as it avoids having to deal with this time offset explicitly.
208 */
209static void timekeeping_forward_now(void)
210{
211 cycle_t cycle_now, cycle_delta;
212 struct clocksource *clock;
213 s64 nsec;
214
215 clock = timekeeper.clock;
216 cycle_now = clock->read(clock);
217 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
218 clock->cycle_last = cycle_now;
219
220 nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
221 timekeeper.shift);
222
223 /* If arch requires, add in gettimeoffset() */
224 nsec += arch_gettimeoffset();
225
226 timespec_add_ns(&timekeeper.xtime, nsec);
227
228 nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
229 timespec_add_ns(&timekeeper.raw_time, nsec);
230}
231
232/**
233 * getnstimeofday - Returns the time of day in a timespec
234 * @ts: pointer to the timespec to be set
235 *
236 * Returns the time of day in a timespec.
237 */
238void getnstimeofday(struct timespec *ts)
239{
240 unsigned long seq;
241 s64 nsecs;
242
243 WARN_ON(timekeeping_suspended);
244
245 do {
246 seq = read_seqbegin(&timekeeper.lock);
247
248 *ts = timekeeper.xtime;
249 nsecs = timekeeping_get_ns();
250
251 /* If arch requires, add in gettimeoffset() */
252 nsecs += arch_gettimeoffset();
253
254 } while (read_seqretry(&timekeeper.lock, seq));
255
256 timespec_add_ns(ts, nsecs);
257}
258EXPORT_SYMBOL(getnstimeofday);
259
260ktime_t ktime_get(void)
261{
262 unsigned int seq;
263 s64 secs, nsecs;
264
265 WARN_ON(timekeeping_suspended);
266
267 do {
268 seq = read_seqbegin(&timekeeper.lock);
269 secs = timekeeper.xtime.tv_sec +
270 timekeeper.wall_to_monotonic.tv_sec;
271 nsecs = timekeeper.xtime.tv_nsec +
272 timekeeper.wall_to_monotonic.tv_nsec;
273 nsecs += timekeeping_get_ns();
274 /* If arch requires, add in gettimeoffset() */
275 nsecs += arch_gettimeoffset();
276
277 } while (read_seqretry(&timekeeper.lock, seq));
278 /*
279 * Use ktime_set/ktime_add_ns to create a proper ktime on
280 * 32-bit architectures without CONFIG_KTIME_SCALAR.
281 */
282 return ktime_add_ns(ktime_set(secs, 0), nsecs);
283}
284EXPORT_SYMBOL_GPL(ktime_get);
285
286/**
287 * ktime_get_ts - get the monotonic clock in timespec format
288 * @ts: pointer to timespec variable
289 *
290 * The function calculates the monotonic clock from the realtime
291 * clock and the wall_to_monotonic offset and stores the result
292 * in normalized timespec format in the variable pointed to by @ts.
293 */
294void ktime_get_ts(struct timespec *ts)
295{
296 struct timespec tomono;
297 unsigned int seq;
298 s64 nsecs;
299
300 WARN_ON(timekeeping_suspended);
301
302 do {
303 seq = read_seqbegin(&timekeeper.lock);
304 *ts = timekeeper.xtime;
305 tomono = timekeeper.wall_to_monotonic;
306 nsecs = timekeeping_get_ns();
307 /* If arch requires, add in gettimeoffset() */
308 nsecs += arch_gettimeoffset();
309
310 } while (read_seqretry(&timekeeper.lock, seq));
311
312 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
313 ts->tv_nsec + tomono.tv_nsec + nsecs);
314}
315EXPORT_SYMBOL_GPL(ktime_get_ts);
316
317#ifdef CONFIG_NTP_PPS
318
319/**
320 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
321 * @ts_raw: pointer to the timespec to be set to raw monotonic time
322 * @ts_real: pointer to the timespec to be set to the time of day
323 *
324 * This function reads both the time of day and raw monotonic time at the
325 * same time atomically and stores the resulting timestamps in timespec
326 * format.
327 */
328void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
329{
330 unsigned long seq;
331 s64 nsecs_raw, nsecs_real;
332
333 WARN_ON_ONCE(timekeeping_suspended);
334
335 do {
336 u32 arch_offset;
337
338 seq = read_seqbegin(&timekeeper.lock);
339
340 *ts_raw = timekeeper.raw_time;
341 *ts_real = timekeeper.xtime;
342
343 nsecs_raw = timekeeping_get_ns_raw();
344 nsecs_real = timekeeping_get_ns();
345
346 /* If arch requires, add in gettimeoffset() */
347 arch_offset = arch_gettimeoffset();
348 nsecs_raw += arch_offset;
349 nsecs_real += arch_offset;
350
351 } while (read_seqretry(&timekeeper.lock, seq));
352
353 timespec_add_ns(ts_raw, nsecs_raw);
354 timespec_add_ns(ts_real, nsecs_real);
355}
356EXPORT_SYMBOL(getnstime_raw_and_real);
357
358#endif /* CONFIG_NTP_PPS */
359
360/**
361 * do_gettimeofday - Returns the time of day in a timeval
362 * @tv: pointer to the timeval to be set
363 *
364 * NOTE: Users should be converted to using getnstimeofday()
365 */
366void do_gettimeofday(struct timeval *tv)
367{
368 struct timespec now;
369
370 getnstimeofday(&now);
371 tv->tv_sec = now.tv_sec;
372 tv->tv_usec = now.tv_nsec/1000;
373}
374EXPORT_SYMBOL(do_gettimeofday);
375
376/**
377 * do_settimeofday - Sets the time of day
378 * @tv: pointer to the timespec variable containing the new time
379 *
380 * Sets the time of day to the new time and update NTP and notify hrtimers
381 */
382int do_settimeofday(const struct timespec *tv)
383{
384 struct timespec ts_delta;
385 unsigned long flags;
386
387 if (!timespec_valid_strict(tv))
388 return -EINVAL;
389
390 write_seqlock_irqsave(&timekeeper.lock, flags);
391
392 timekeeping_forward_now();
393
394 ts_delta.tv_sec = tv->tv_sec - timekeeper.xtime.tv_sec;
395 ts_delta.tv_nsec = tv->tv_nsec - timekeeper.xtime.tv_nsec;
396 timekeeper.wall_to_monotonic =
397 timespec_sub(timekeeper.wall_to_monotonic, ts_delta);
398
399 timekeeper.xtime = *tv;
400 timekeeping_update(true);
401
402 write_sequnlock_irqrestore(&timekeeper.lock, flags);
403
404 /* signal hrtimers about time change */
405 clock_was_set();
406
407 return 0;
408}
409EXPORT_SYMBOL(do_settimeofday);
410
411
412/**
413 * timekeeping_inject_offset - Adds or subtracts from the current time.
414 * @tv: pointer to the timespec variable containing the offset
415 *
416 * Adds or subtracts an offset value from the current time.
417 */
418int timekeeping_inject_offset(struct timespec *ts)
419{
420 unsigned long flags;
421 struct timespec tmp;
422 int ret = 0;
423
424 if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
425 return -EINVAL;
426
427 write_seqlock_irqsave(&timekeeper.lock, flags);
428
429 timekeeping_forward_now();
430
431 tmp = timespec_add(timekeeper.xtime, *ts);
432 if (!timespec_valid_strict(&tmp)) {
433 ret = -EINVAL;
434 goto error;
435 }
436
437 timekeeper.xtime = timespec_add(timekeeper.xtime, *ts);
438 timekeeper.wall_to_monotonic =
439 timespec_sub(timekeeper.wall_to_monotonic, *ts);
440
441error: /* even if we error out, we forwarded the time, so call update */
442 timekeeping_update(true);
443
444 write_sequnlock_irqrestore(&timekeeper.lock, flags);
445
446 /* signal hrtimers about time change */
447 clock_was_set();
448
449 return ret;
450}
451EXPORT_SYMBOL(timekeeping_inject_offset);
452
453/**
454 * change_clocksource - Swaps clocksources if a new one is available
455 *
456 * Accumulates current time interval and initializes new clocksource
457 */
458static int change_clocksource(void *data)
459{
460 struct clocksource *new, *old;
461 unsigned long flags;
462
463 new = (struct clocksource *) data;
464
465 write_seqlock_irqsave(&timekeeper.lock, flags);
466
467 timekeeping_forward_now();
468 if (!new->enable || new->enable(new) == 0) {
469 old = timekeeper.clock;
470 timekeeper_setup_internals(new);
471 if (old->disable)
472 old->disable(old);
473 }
474 timekeeping_update(true);
475
476 write_sequnlock_irqrestore(&timekeeper.lock, flags);
477
478 return 0;
479}
480
481/**
482 * timekeeping_notify - Install a new clock source
483 * @clock: pointer to the clock source
484 *
485 * This function is called from clocksource.c after a new, better clock
486 * source has been registered. The caller holds the clocksource_mutex.
487 */
488void timekeeping_notify(struct clocksource *clock)
489{
490 if (timekeeper.clock == clock)
491 return;
492 stop_machine(change_clocksource, clock, NULL);
493 tick_clock_notify();
494}
495
496/**
497 * ktime_get_real - get the real (wall-) time in ktime_t format
498 *
499 * returns the time in ktime_t format
500 */
501ktime_t ktime_get_real(void)
502{
503 struct timespec now;
504
505 getnstimeofday(&now);
506
507 return timespec_to_ktime(now);
508}
509EXPORT_SYMBOL_GPL(ktime_get_real);
510
511/**
512 * getrawmonotonic - Returns the raw monotonic time in a timespec
513 * @ts: pointer to the timespec to be set
514 *
515 * Returns the raw monotonic time (completely un-modified by ntp)
516 */
517void getrawmonotonic(struct timespec *ts)
518{
519 unsigned long seq;
520 s64 nsecs;
521
522 do {
523 seq = read_seqbegin(&timekeeper.lock);
524 nsecs = timekeeping_get_ns_raw();
525 *ts = timekeeper.raw_time;
526
527 } while (read_seqretry(&timekeeper.lock, seq));
528
529 timespec_add_ns(ts, nsecs);
530}
531EXPORT_SYMBOL(getrawmonotonic);
532
533
534/**
535 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
536 */
537int timekeeping_valid_for_hres(void)
538{
539 unsigned long seq;
540 int ret;
541
542 do {
543 seq = read_seqbegin(&timekeeper.lock);
544
545 ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
546
547 } while (read_seqretry(&timekeeper.lock, seq));
548
549 return ret;
550}
551
552/**
553 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
554 */
555u64 timekeeping_max_deferment(void)
556{
557 unsigned long seq;
558 u64 ret;
559 do {
560 seq = read_seqbegin(&timekeeper.lock);
561
562 ret = timekeeper.clock->max_idle_ns;
563
564 } while (read_seqretry(&timekeeper.lock, seq));
565
566 return ret;
567}
568
569/**
570 * read_persistent_clock - Return time from the persistent clock.
571 *
572 * Weak dummy function for arches that do not yet support it.
573 * Reads the time from the battery backed persistent clock.
574 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
575 *
576 * XXX - Do be sure to remove it once all arches implement it.
577 */
578void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
579{
580 ts->tv_sec = 0;
581 ts->tv_nsec = 0;
582}
583
584/**
585 * read_boot_clock - Return time of the system start.
586 *
587 * Weak dummy function for arches that do not yet support it.
588 * Function to read the exact time the system has been started.
589 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
590 *
591 * XXX - Do be sure to remove it once all arches implement it.
592 */
593void __attribute__((weak)) read_boot_clock(struct timespec *ts)
594{
595 ts->tv_sec = 0;
596 ts->tv_nsec = 0;
597}
598
599/*
600 * timekeeping_init - Initializes the clocksource and common timekeeping values
601 */
602void __init timekeeping_init(void)
603{
604 struct clocksource *clock;
605 unsigned long flags;
606 struct timespec now, boot;
607
608 read_persistent_clock(&now);
609 if (!timespec_valid_strict(&now)) {
610 pr_warn("WARNING: Persistent clock returned invalid value!\n"
611 " Check your CMOS/BIOS settings.\n");
612 now.tv_sec = 0;
613 now.tv_nsec = 0;
614 }
615
616 read_boot_clock(&boot);
617 if (!timespec_valid_strict(&boot)) {
618 pr_warn("WARNING: Boot clock returned invalid value!\n"
619 " Check your CMOS/BIOS settings.\n");
620 boot.tv_sec = 0;
621 boot.tv_nsec = 0;
622 }
623
624 seqlock_init(&timekeeper.lock);
625
626 ntp_init();
627
628 write_seqlock_irqsave(&timekeeper.lock, flags);
629 clock = clocksource_default_clock();
630 if (clock->enable)
631 clock->enable(clock);
632 timekeeper_setup_internals(clock);
633
634 timekeeper.xtime.tv_sec = now.tv_sec;
635 timekeeper.xtime.tv_nsec = now.tv_nsec;
636 timekeeper.raw_time.tv_sec = 0;
637 timekeeper.raw_time.tv_nsec = 0;
638 if (boot.tv_sec == 0 && boot.tv_nsec == 0) {
639 boot.tv_sec = timekeeper.xtime.tv_sec;
640 boot.tv_nsec = timekeeper.xtime.tv_nsec;
641 }
642 set_normalized_timespec(&timekeeper.wall_to_monotonic,
643 -boot.tv_sec, -boot.tv_nsec);
644 update_rt_offset();
645 timekeeper.total_sleep_time.tv_sec = 0;
646 timekeeper.total_sleep_time.tv_nsec = 0;
647 write_sequnlock_irqrestore(&timekeeper.lock, flags);
648}
649
650/* time in seconds when suspend began */
651static struct timespec timekeeping_suspend_time;
652
653static void update_sleep_time(struct timespec t)
654{
655 timekeeper.total_sleep_time = t;
656 timekeeper.offs_boot = timespec_to_ktime(t);
657}
658
659/**
660 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
661 * @delta: pointer to a timespec delta value
662 *
663 * Takes a timespec offset measuring a suspend interval and properly
664 * adds the sleep offset to the timekeeping variables.
665 */
666static void __timekeeping_inject_sleeptime(struct timespec *delta)
667{
668 if (!timespec_valid_strict(delta)) {
669 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
670 "sleep delta value!\n");
671 return;
672 }
673
674 timekeeper.xtime = timespec_add(timekeeper.xtime, *delta);
675 timekeeper.wall_to_monotonic =
676 timespec_sub(timekeeper.wall_to_monotonic, *delta);
677 update_sleep_time(timespec_add(timekeeper.total_sleep_time, *delta));
678}
679
680
681/**
682 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
683 * @delta: pointer to a timespec delta value
684 *
685 * This hook is for architectures that cannot support read_persistent_clock
686 * because their RTC/persistent clock is only accessible when irqs are enabled.
687 *
688 * This function should only be called by rtc_resume(), and allows
689 * a suspend offset to be injected into the timekeeping values.
690 */
691void timekeeping_inject_sleeptime(struct timespec *delta)
692{
693 unsigned long flags;
694 struct timespec ts;
695
696 /* Make sure we don't set the clock twice */
697 read_persistent_clock(&ts);
698 if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
699 return;
700
701 write_seqlock_irqsave(&timekeeper.lock, flags);
702
703 timekeeping_forward_now();
704
705 __timekeeping_inject_sleeptime(delta);
706
707 timekeeping_update(true);
708
709 write_sequnlock_irqrestore(&timekeeper.lock, flags);
710
711 /* signal hrtimers about time change */
712 clock_was_set();
713}
714
715
716/**
717 * timekeeping_resume - Resumes the generic timekeeping subsystem.
718 *
719 * This is for the generic clocksource timekeeping.
720 * xtime/wall_to_monotonic/jiffies/etc are
721 * still managed by arch specific suspend/resume code.
722 */
723static void timekeeping_resume(void)
724{
725 unsigned long flags;
726 struct timespec ts;
727
728 read_persistent_clock(&ts);
729
730 clocksource_resume();
731
732 write_seqlock_irqsave(&timekeeper.lock, flags);
733
734 if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
735 ts = timespec_sub(ts, timekeeping_suspend_time);
736 __timekeeping_inject_sleeptime(&ts);
737 }
738 /* re-base the last cycle value */
739 timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
740 timekeeper.ntp_error = 0;
741 timekeeping_suspended = 0;
742 timekeeping_update(false);
743 write_sequnlock_irqrestore(&timekeeper.lock, flags);
744
745 touch_softlockup_watchdog();
746
747 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
748
749 /* Resume hrtimers */
750 hrtimers_resume();
751}
752
753static int timekeeping_suspend(void)
754{
755 unsigned long flags;
756 struct timespec delta, delta_delta;
757 static struct timespec old_delta;
758
759 read_persistent_clock(&timekeeping_suspend_time);
760
761 write_seqlock_irqsave(&timekeeper.lock, flags);
762 timekeeping_forward_now();
763 timekeeping_suspended = 1;
764
765 /*
766 * To avoid drift caused by repeated suspend/resumes,
767 * which each can add ~1 second drift error,
768 * try to compensate so the difference in system time
769 * and persistent_clock time stays close to constant.
770 */
771 delta = timespec_sub(timekeeper.xtime, timekeeping_suspend_time);
772 delta_delta = timespec_sub(delta, old_delta);
773 if (abs(delta_delta.tv_sec) >= 2) {
774 /*
775 * if delta_delta is too large, assume time correction
776 * has occured and set old_delta to the current delta.
777 */
778 old_delta = delta;
779 } else {
780 /* Otherwise try to adjust old_system to compensate */
781 timekeeping_suspend_time =
782 timespec_add(timekeeping_suspend_time, delta_delta);
783 }
784 write_sequnlock_irqrestore(&timekeeper.lock, flags);
785
786 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
787 clocksource_suspend();
788
789 return 0;
790}
791
792/* sysfs resume/suspend bits for timekeeping */
793static struct syscore_ops timekeeping_syscore_ops = {
794 .resume = timekeeping_resume,
795 .suspend = timekeeping_suspend,
796};
797
798static int __init timekeeping_init_ops(void)
799{
800 register_syscore_ops(&timekeeping_syscore_ops);
801 return 0;
802}
803
804device_initcall(timekeeping_init_ops);
805
806/*
807 * If the error is already larger, we look ahead even further
808 * to compensate for late or lost adjustments.
809 */
810static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval,
811 s64 *offset)
812{
813 s64 tick_error, i;
814 u32 look_ahead, adj;
815 s32 error2, mult;
816
817 /*
818 * Use the current error value to determine how much to look ahead.
819 * The larger the error the slower we adjust for it to avoid problems
820 * with losing too many ticks, otherwise we would overadjust and
821 * produce an even larger error. The smaller the adjustment the
822 * faster we try to adjust for it, as lost ticks can do less harm
823 * here. This is tuned so that an error of about 1 msec is adjusted
824 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
825 */
826 error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
827 error2 = abs(error2);
828 for (look_ahead = 0; error2 > 0; look_ahead++)
829 error2 >>= 2;
830
831 /*
832 * Now calculate the error in (1 << look_ahead) ticks, but first
833 * remove the single look ahead already included in the error.
834 */
835 tick_error = ntp_tick_length() >> (timekeeper.ntp_error_shift + 1);
836 tick_error -= timekeeper.xtime_interval >> 1;
837 error = ((error - tick_error) >> look_ahead) + tick_error;
838
839 /* Finally calculate the adjustment shift value. */
840 i = *interval;
841 mult = 1;
842 if (error < 0) {
843 error = -error;
844 *interval = -*interval;
845 *offset = -*offset;
846 mult = -1;
847 }
848 for (adj = 0; error > i; adj++)
849 error >>= 1;
850
851 *interval <<= adj;
852 *offset <<= adj;
853 return mult << adj;
854}
855
856/*
857 * Adjust the multiplier to reduce the error value,
858 * this is optimized for the most common adjustments of -1,0,1,
859 * for other values we can do a bit more work.
860 */
861static void timekeeping_adjust(s64 offset)
862{
863 s64 error, interval = timekeeper.cycle_interval;
864 int adj;
865
866 /*
867 * The point of this is to check if the error is greater than half
868 * an interval.
869 *
870 * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
871 *
872 * Note we subtract one in the shift, so that error is really error*2.
873 * This "saves" dividing(shifting) interval twice, but keeps the
874 * (error > interval) comparison as still measuring if error is
875 * larger than half an interval.
876 *
877 * Note: It does not "save" on aggravation when reading the code.
878 */
879 error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1);
880 if (error > interval) {
881 /*
882 * We now divide error by 4(via shift), which checks if
883 * the error is greater than twice the interval.
884 * If it is greater, we need a bigadjust, if its smaller,
885 * we can adjust by 1.
886 */
887 error >>= 2;
888 /*
889 * XXX - In update_wall_time, we round up to the next
890 * nanosecond, and store the amount rounded up into
891 * the error. This causes the likely below to be unlikely.
892 *
893 * The proper fix is to avoid rounding up by using
894 * the high precision timekeeper.xtime_nsec instead of
895 * xtime.tv_nsec everywhere. Fixing this will take some
896 * time.
897 */
898 if (likely(error <= interval))
899 adj = 1;
900 else
901 adj = timekeeping_bigadjust(error, &interval, &offset);
902 } else if (error < -interval) {
903 /* See comment above, this is just switched for the negative */
904 error >>= 2;
905 if (likely(error >= -interval)) {
906 adj = -1;
907 interval = -interval;
908 offset = -offset;
909 } else
910 adj = timekeeping_bigadjust(error, &interval, &offset);
911 } else /* No adjustment needed */
912 return;
913
914 if (unlikely(timekeeper.clock->maxadj &&
915 (timekeeper.mult + adj >
916 timekeeper.clock->mult + timekeeper.clock->maxadj))) {
917 printk_once(KERN_WARNING
918 "Adjusting %s more than 11%% (%ld vs %ld)\n",
919 timekeeper.clock->name, (long)timekeeper.mult + adj,
920 (long)timekeeper.clock->mult +
921 timekeeper.clock->maxadj);
922 }
923 /*
924 * So the following can be confusing.
925 *
926 * To keep things simple, lets assume adj == 1 for now.
927 *
928 * When adj != 1, remember that the interval and offset values
929 * have been appropriately scaled so the math is the same.
930 *
931 * The basic idea here is that we're increasing the multiplier
932 * by one, this causes the xtime_interval to be incremented by
933 * one cycle_interval. This is because:
934 * xtime_interval = cycle_interval * mult
935 * So if mult is being incremented by one:
936 * xtime_interval = cycle_interval * (mult + 1)
937 * Its the same as:
938 * xtime_interval = (cycle_interval * mult) + cycle_interval
939 * Which can be shortened to:
940 * xtime_interval += cycle_interval
941 *
942 * So offset stores the non-accumulated cycles. Thus the current
943 * time (in shifted nanoseconds) is:
944 * now = (offset * adj) + xtime_nsec
945 * Now, even though we're adjusting the clock frequency, we have
946 * to keep time consistent. In other words, we can't jump back
947 * in time, and we also want to avoid jumping forward in time.
948 *
949 * So given the same offset value, we need the time to be the same
950 * both before and after the freq adjustment.
951 * now = (offset * adj_1) + xtime_nsec_1
952 * now = (offset * adj_2) + xtime_nsec_2
953 * So:
954 * (offset * adj_1) + xtime_nsec_1 =
955 * (offset * adj_2) + xtime_nsec_2
956 * And we know:
957 * adj_2 = adj_1 + 1
958 * So:
959 * (offset * adj_1) + xtime_nsec_1 =
960 * (offset * (adj_1+1)) + xtime_nsec_2
961 * (offset * adj_1) + xtime_nsec_1 =
962 * (offset * adj_1) + offset + xtime_nsec_2
963 * Canceling the sides:
964 * xtime_nsec_1 = offset + xtime_nsec_2
965 * Which gives us:
966 * xtime_nsec_2 = xtime_nsec_1 - offset
967 * Which simplfies to:
968 * xtime_nsec -= offset
969 *
970 * XXX - TODO: Doc ntp_error calculation.
971 */
972 timekeeper.mult += adj;
973 timekeeper.xtime_interval += interval;
974 timekeeper.xtime_nsec -= offset;
975 timekeeper.ntp_error -= (interval - offset) <<
976 timekeeper.ntp_error_shift;
977}
978
979
980/**
981 * logarithmic_accumulation - shifted accumulation of cycles
982 *
983 * This functions accumulates a shifted interval of cycles into
984 * into a shifted interval nanoseconds. Allows for O(log) accumulation
985 * loop.
986 *
987 * Returns the unconsumed cycles.
988 */
989static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
990{
991 u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
992 u64 raw_nsecs;
993
994 /* If the offset is smaller than a shifted interval, do nothing */
995 if (offset < timekeeper.cycle_interval<<shift)
996 return offset;
997
998 /* Accumulate one shifted interval */
999 offset -= timekeeper.cycle_interval << shift;
1000 timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift;
1001
1002 timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
1003 while (timekeeper.xtime_nsec >= nsecps) {
1004 int leap;
1005 timekeeper.xtime_nsec -= nsecps;
1006 timekeeper.xtime.tv_sec++;
1007 leap = second_overflow(timekeeper.xtime.tv_sec);
1008 timekeeper.xtime.tv_sec += leap;
1009 timekeeper.wall_to_monotonic.tv_sec -= leap;
1010 if (leap)
1011 clock_was_set_delayed();
1012 }
1013
1014 /* Accumulate raw time */
1015 raw_nsecs = timekeeper.raw_interval << shift;
1016 raw_nsecs += timekeeper.raw_time.tv_nsec;
1017 if (raw_nsecs >= NSEC_PER_SEC) {
1018 u64 raw_secs = raw_nsecs;
1019 raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
1020 timekeeper.raw_time.tv_sec += raw_secs;
1021 }
1022 timekeeper.raw_time.tv_nsec = raw_nsecs;
1023
1024 /* Accumulate error between NTP and clock interval */
1025 timekeeper.ntp_error += ntp_tick_length() << shift;
1026 timekeeper.ntp_error -=
1027 (timekeeper.xtime_interval + timekeeper.xtime_remainder) <<
1028 (timekeeper.ntp_error_shift + shift);
1029
1030 return offset;
1031}
1032
1033
1034/**
1035 * update_wall_time - Uses the current clocksource to increment the wall time
1036 *
1037 */
1038static void update_wall_time(void)
1039{
1040 struct clocksource *clock;
1041 cycle_t offset;
1042 int shift = 0, maxshift;
1043 unsigned long flags;
1044
1045 write_seqlock_irqsave(&timekeeper.lock, flags);
1046
1047 /* Make sure we're fully resumed: */
1048 if (unlikely(timekeeping_suspended))
1049 goto out;
1050
1051 clock = timekeeper.clock;
1052
1053#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1054 offset = timekeeper.cycle_interval;
1055#else
1056 offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
1057#endif
1058 /* Check if there's really nothing to do */
1059 if (offset < timekeeper.cycle_interval)
1060 goto out;
1061
1062 timekeeper.xtime_nsec = (s64)timekeeper.xtime.tv_nsec <<
1063 timekeeper.shift;
1064
1065 /*
1066 * With NO_HZ we may have to accumulate many cycle_intervals
1067 * (think "ticks") worth of time at once. To do this efficiently,
1068 * we calculate the largest doubling multiple of cycle_intervals
1069 * that is smaller than the offset. We then accumulate that
1070 * chunk in one go, and then try to consume the next smaller
1071 * doubled multiple.
1072 */
1073 shift = ilog2(offset) - ilog2(timekeeper.cycle_interval);
1074 shift = max(0, shift);
1075 /* Bound shift to one less than what overflows tick_length */
1076 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
1077 shift = min(shift, maxshift);
1078 while (offset >= timekeeper.cycle_interval) {
1079 offset = logarithmic_accumulation(offset, shift);
1080 if(offset < timekeeper.cycle_interval<<shift)
1081 shift--;
1082 }
1083
1084 /* correct the clock when NTP error is too big */
1085 timekeeping_adjust(offset);
1086
1087 /*
1088 * Since in the loop above, we accumulate any amount of time
1089 * in xtime_nsec over a second into xtime.tv_sec, its possible for
1090 * xtime_nsec to be fairly small after the loop. Further, if we're
1091 * slightly speeding the clocksource up in timekeeping_adjust(),
1092 * its possible the required corrective factor to xtime_nsec could
1093 * cause it to underflow.
1094 *
1095 * Now, we cannot simply roll the accumulated second back, since
1096 * the NTP subsystem has been notified via second_overflow. So
1097 * instead we push xtime_nsec forward by the amount we underflowed,
1098 * and add that amount into the error.
1099 *
1100 * We'll correct this error next time through this function, when
1101 * xtime_nsec is not as small.
1102 */
1103 if (unlikely((s64)timekeeper.xtime_nsec < 0)) {
1104 s64 neg = -(s64)timekeeper.xtime_nsec;
1105 timekeeper.xtime_nsec = 0;
1106 timekeeper.ntp_error += neg << timekeeper.ntp_error_shift;
1107 }
1108
1109
1110 /*
1111 * Store full nanoseconds into xtime after rounding it up and
1112 * add the remainder to the error difference.
1113 */
1114 timekeeper.xtime.tv_nsec = ((s64)timekeeper.xtime_nsec >>
1115 timekeeper.shift) + 1;
1116 timekeeper.xtime_nsec -= (s64)timekeeper.xtime.tv_nsec <<
1117 timekeeper.shift;
1118 timekeeper.ntp_error += timekeeper.xtime_nsec <<
1119 timekeeper.ntp_error_shift;
1120
1121 /*
1122 * Finally, make sure that after the rounding
1123 * xtime.tv_nsec isn't larger than NSEC_PER_SEC
1124 */
1125 if (unlikely(timekeeper.xtime.tv_nsec >= NSEC_PER_SEC)) {
1126 int leap;
1127 timekeeper.xtime.tv_nsec -= NSEC_PER_SEC;
1128 timekeeper.xtime.tv_sec++;
1129 leap = second_overflow(timekeeper.xtime.tv_sec);
1130 timekeeper.xtime.tv_sec += leap;
1131 timekeeper.wall_to_monotonic.tv_sec -= leap;
1132 if (leap)
1133 clock_was_set_delayed();
1134 }
1135
1136 timekeeping_update(false);
1137
1138out:
1139 write_sequnlock_irqrestore(&timekeeper.lock, flags);
1140
1141}
1142
1143/**
1144 * getboottime - Return the real time of system boot.
1145 * @ts: pointer to the timespec to be set
1146 *
1147 * Returns the wall-time of boot in a timespec.
1148 *
1149 * This is based on the wall_to_monotonic offset and the total suspend
1150 * time. Calls to settimeofday will affect the value returned (which
1151 * basically means that however wrong your real time clock is at boot time,
1152 * you get the right time here).
1153 */
1154void getboottime(struct timespec *ts)
1155{
1156 struct timespec boottime = {
1157 .tv_sec = timekeeper.wall_to_monotonic.tv_sec +
1158 timekeeper.total_sleep_time.tv_sec,
1159 .tv_nsec = timekeeper.wall_to_monotonic.tv_nsec +
1160 timekeeper.total_sleep_time.tv_nsec
1161 };
1162
1163 set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
1164}
1165EXPORT_SYMBOL_GPL(getboottime);
1166
1167
1168/**
1169 * get_monotonic_boottime - Returns monotonic time since boot
1170 * @ts: pointer to the timespec to be set
1171 *
1172 * Returns the monotonic time since boot in a timespec.
1173 *
1174 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1175 * includes the time spent in suspend.
1176 */
1177void get_monotonic_boottime(struct timespec *ts)
1178{
1179 struct timespec tomono, sleep;
1180 unsigned int seq;
1181 s64 nsecs;
1182
1183 WARN_ON(timekeeping_suspended);
1184
1185 do {
1186 seq = read_seqbegin(&timekeeper.lock);
1187 *ts = timekeeper.xtime;
1188 tomono = timekeeper.wall_to_monotonic;
1189 sleep = timekeeper.total_sleep_time;
1190 nsecs = timekeeping_get_ns();
1191
1192 } while (read_seqretry(&timekeeper.lock, seq));
1193
1194 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,
1195 ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
1196}
1197EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1198
1199/**
1200 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1201 *
1202 * Returns the monotonic time since boot in a ktime
1203 *
1204 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1205 * includes the time spent in suspend.
1206 */
1207ktime_t ktime_get_boottime(void)
1208{
1209 struct timespec ts;
1210
1211 get_monotonic_boottime(&ts);
1212 return timespec_to_ktime(ts);
1213}
1214EXPORT_SYMBOL_GPL(ktime_get_boottime);
1215
1216/**
1217 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1218 * @ts: pointer to the timespec to be converted
1219 */
1220void monotonic_to_bootbased(struct timespec *ts)
1221{
1222 *ts = timespec_add(*ts, timekeeper.total_sleep_time);
1223}
1224EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1225
1226unsigned long get_seconds(void)
1227{
1228 return timekeeper.xtime.tv_sec;
1229}
1230EXPORT_SYMBOL(get_seconds);
1231
1232struct timespec __current_kernel_time(void)
1233{
1234 return timekeeper.xtime;
1235}
1236
1237struct timespec current_kernel_time(void)
1238{
1239 struct timespec now;
1240 unsigned long seq;
1241
1242 do {
1243 seq = read_seqbegin(&timekeeper.lock);
1244
1245 now = timekeeper.xtime;
1246 } while (read_seqretry(&timekeeper.lock, seq));
1247
1248 return now;
1249}
1250EXPORT_SYMBOL(current_kernel_time);
1251
1252struct timespec get_monotonic_coarse(void)
1253{
1254 struct timespec now, mono;
1255 unsigned long seq;
1256
1257 do {
1258 seq = read_seqbegin(&timekeeper.lock);
1259
1260 now = timekeeper.xtime;
1261 mono = timekeeper.wall_to_monotonic;
1262 } while (read_seqretry(&timekeeper.lock, seq));
1263
1264 set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1265 now.tv_nsec + mono.tv_nsec);
1266 return now;
1267}
1268
1269/*
1270 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1271 * without sampling the sequence number in xtime_lock.
1272 * jiffies is defined in the linker script...
1273 */
1274void do_timer(unsigned long ticks)
1275{
1276 jiffies_64 += ticks;
1277 update_wall_time();
1278 calc_global_load(ticks);
1279}
1280
1281/**
1282 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1283 * and sleep offsets.
1284 * @xtim: pointer to timespec to be set with xtime
1285 * @wtom: pointer to timespec to be set with wall_to_monotonic
1286 * @sleep: pointer to timespec to be set with time in suspend
1287 */
1288void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1289 struct timespec *wtom, struct timespec *sleep)
1290{
1291 unsigned long seq;
1292
1293 do {
1294 seq = read_seqbegin(&timekeeper.lock);
1295 *xtim = timekeeper.xtime;
1296 *wtom = timekeeper.wall_to_monotonic;
1297 *sleep = timekeeper.total_sleep_time;
1298 } while (read_seqretry(&timekeeper.lock, seq));
1299}
1300
1301#ifdef CONFIG_HIGH_RES_TIMERS
1302/**
1303 * ktime_get_update_offsets - hrtimer helper
1304 * @offs_real: pointer to storage for monotonic -> realtime offset
1305 * @offs_boot: pointer to storage for monotonic -> boottime offset
1306 *
1307 * Returns current monotonic time and updates the offsets
1308 * Called from hrtimer_interupt() or retrigger_next_event()
1309 */
1310ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
1311{
1312 ktime_t now;
1313 unsigned int seq;
1314 u64 secs, nsecs;
1315
1316 do {
1317 seq = read_seqbegin(&timekeeper.lock);
1318
1319 secs = timekeeper.xtime.tv_sec;
1320 nsecs = timekeeper.xtime.tv_nsec;
1321 nsecs += timekeeping_get_ns();
1322 /* If arch requires, add in gettimeoffset() */
1323 nsecs += arch_gettimeoffset();
1324
1325 *offs_real = timekeeper.offs_real;
1326 *offs_boot = timekeeper.offs_boot;
1327 } while (read_seqretry(&timekeeper.lock, seq));
1328
1329 now = ktime_add_ns(ktime_set(secs, 0), nsecs);
1330 now = ktime_sub(now, *offs_real);
1331 return now;
1332}
1333#endif
1334
1335/**
1336 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1337 */
1338ktime_t ktime_get_monotonic_offset(void)
1339{
1340 unsigned long seq;
1341 struct timespec wtom;
1342
1343 do {
1344 seq = read_seqbegin(&timekeeper.lock);
1345 wtom = timekeeper.wall_to_monotonic;
1346 } while (read_seqretry(&timekeeper.lock, seq));
1347
1348 return timespec_to_ktime(wtom);
1349}
1350EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
1351
1352
1353/**
1354 * xtime_update() - advances the timekeeping infrastructure
1355 * @ticks: number of ticks, that have elapsed since the last call.
1356 *
1357 * Must be called with interrupts disabled.
1358 */
1359void xtime_update(unsigned long ticks)
1360{
1361 write_seqlock(&xtime_lock);
1362 do_timer(ticks);
1363 write_sequnlock(&xtime_lock);
1364}