1	// SPDX-License-Identifier: GPL-2.0
2	/*
3	* Kernel timekeeping code and accessor functions. Based on code from
4	* timer.c, moved in commit 8524070b7982.
5	*/
6	#include <linux/timekeeper_internal.h>
7	#include <linux/module.h>
8	#include <linux/interrupt.h>
9	#include <linux/percpu.h>
10	#include <linux/init.h>
11	#include <linux/mm.h>
12	#include <linux/nmi.h>
13	#include <linux/sched.h>
14	#include <linux/sched/loadavg.h>
15	#include <linux/sched/clock.h>
16	#include <linux/syscore_ops.h>
17	#include <linux/clocksource.h>
18	#include <linux/jiffies.h>
19	#include <linux/time.h>
20	#include <linux/timex.h>
21	#include <linux/tick.h>
22	#include <linux/stop_machine.h>
23	#include <linux/pvclock_gtod.h>
24	#include <linux/compiler.h>
25	#include <linux/audit.h>
26	#include <linux/random.h>
27
28	#include "tick-internal.h"
29	#include "ntp_internal.h"
30	#include "timekeeping_internal.h"
31
32	#define TK_CLEAR_NTP (1 << 0)
33	#define TK_MIRROR (1 << 1)
34	#define TK_CLOCK_WAS_SET (1 << 2)
35
36	enum timekeeping_adv_mode {
37	/* Update timekeeper when a tick has passed */
38	TK_ADV_TICK,
39
40	/* Update timekeeper on a direct frequency change */
41	TK_ADV_FREQ
42	};
43
44	DEFINE_RAW_SPINLOCK(timekeeper_lock);
45
46	/*
47	* The most important data for readout fits into a single 64 byte
48	* cache line.
49	*/
50	static struct {
51	seqcount_raw_spinlock_t seq;
52	struct timekeeper timekeeper;
53	} tk_core ____cacheline_aligned = {
54	.seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock),
55	};
56
57	static struct timekeeper shadow_timekeeper;
58
59	/* flag for if timekeeping is suspended */
60	int __read_mostly timekeeping_suspended;
61
62	/**
63	* struct tk_fast - NMI safe timekeeper
64	* @seq: Sequence counter for protecting updates. The lowest bit
65	* is the index for the tk_read_base array
66	* @base: tk_read_base array. Access is indexed by the lowest bit of
67	* @seq.
68	*
69	* See @update_fast_timekeeper() below.
70	*/
71	struct tk_fast {
72	seqcount_latch_t seq;
73	struct tk_read_base base[2];
74	};
75
76	/* Suspend-time cycles value for halted fast timekeeper. */
77	static u64 cycles_at_suspend;
78
79	static u64 dummy_clock_read(struct clocksource *cs)
80	{
81	if (timekeeping_suspended)
82	return cycles_at_suspend;
83	return local_clock();
84	}
85
86	static struct clocksource dummy_clock = {
87	.read = dummy_clock_read,
88	};
89
90	/*
91	* Boot time initialization which allows local_clock() to be utilized
92	* during early boot when clocksources are not available. local_clock()
93	* returns nanoseconds already so no conversion is required, hence mult=1
94	* and shift=0. When the first proper clocksource is installed then
95	* the fast time keepers are updated with the correct values.
96	*/
97	#define FAST_TK_INIT \
98	{ \
99	.clock = &dummy_clock, \
100	.mask = CLOCKSOURCE_MASK(64), \
101	.mult = 1, \
102	.shift = 0, \
103	}
104
105	static struct tk_fast tk_fast_mono ____cacheline_aligned = {
106	.seq = SEQCNT_LATCH_ZERO(tk_fast_mono.seq),
107	.base[0] = FAST_TK_INIT,
108	.base[1] = FAST_TK_INIT,
109	};
110
111	static struct tk_fast tk_fast_raw ____cacheline_aligned = {
112	.seq = SEQCNT_LATCH_ZERO(tk_fast_raw.seq),
113	.base[0] = FAST_TK_INIT,
114	.base[1] = FAST_TK_INIT,
115	};
116
117	static inline void tk_normalize_xtime(struct timekeeper *tk)
118	{
119	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
129	static 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
138	static 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
144	static 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
151	static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
152	{
153	struct timespec64 tmp;
154
155	/*
156	* Verify consistency of: offset_real = -wall_to_monotonic
157	* before modifying anything
158	*/
159	set_normalized_timespec64(ts: &tmp, sec: -tk->wall_to_monotonic.tv_sec,
160	nsec: -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(ts: &tmp, sec: -wtm.tv_sec, nsec: -wtm.tv_nsec);
164	tk->offs_real = timespec64_to_ktime(ts: tmp);
165	tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
166	}
167
168	static 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	*/
191	static 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
201	static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
202	{
203
204	u64 max_cycles = tk->tkr_mono.clock->max_cycles;
205	const char *name = tk->tkr_mono.clock->name;
206
207	if (offset > max_cycles) {
208	printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
209	offset, name, max_cycles);
210	printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
211	} else {
212	if (offset > (max_cycles >> 1)) {
213	printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
214	offset, name, max_cycles >> 1);
215	printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
216	}
217	}
218
219	if (tk->underflow_seen) {
220	if (jiffies - tk->last_warning > WARNING_FREQ) {
221	printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
222	printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
223	printk_deferred(" Your kernel is probably still fine.\n");
224	tk->last_warning = jiffies;
225	}
226	tk->underflow_seen = 0;
227	}
228
229	if (tk->overflow_seen) {
230	if (jiffies - tk->last_warning > WARNING_FREQ) {
231	printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
232	printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
233	printk_deferred(" Your kernel is probably still fine.\n");
234	tk->last_warning = jiffies;
235	}
236	tk->overflow_seen = 0;
237	}
238	}
239
240	static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
241	{
242	struct timekeeper *tk = &tk_core.timekeeper;
243	u64 now, last, mask, max, delta;
244	unsigned int seq;
245
246	/*
247	* Since we're called holding a seqcount, the data may shift
248	* under us while we're doing the calculation. This can cause
249	* false positives, since we'd note a problem but throw the
250	* results away. So nest another seqcount here to atomically
251	* grab the points we are checking with.
252	*/
253	do {
254	seq = read_seqcount_begin(&tk_core.seq);
255	now = tk_clock_read(tkr);
256	last = tkr->cycle_last;
257	mask = tkr->mask;
258	max = tkr->clock->max_cycles;
259	} while (read_seqcount_retry(&tk_core.seq, seq));
260
261	delta = clocksource_delta(now, last, mask);
262
263	/*
264	* Try to catch underflows by checking if we are seeing small
265	* mask-relative negative values.
266	*/
267	if (unlikely((~delta & mask) < (mask >> 3))) {
268	tk->underflow_seen = 1;
269	delta = 0;
270	}
271
272	/* Cap delta value to the max_cycles values to avoid mult overflows */
273	if (unlikely(delta > max)) {
274	tk->overflow_seen = 1;
275	delta = tkr->clock->max_cycles;
276	}
277
278	return delta;
279	}
280	#else
281	static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
282	{
283	}
284	static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
285	{
286	u64 cycle_now, delta;
287
288	/* read clocksource */
289	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	*/
309	static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
310	{
311	u64 interval;
312	u64 tmp, ntpinterval;
313	struct clocksource *old_clock;
314
315	++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(tkr: &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
374	static 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
384	static 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
392	static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
393	{
394	u64 delta;
395
396	/* calculate the delta since the last update_wall_time */
397	delta = clocksource_delta(now: cycles, last: tkr->cycle_last, mask: 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	*/
416	static 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(s: &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(s: &tkf->seq);
429
430	/* Update base[1] */
431	memcpy(base + 1, base, sizeof(*base));
432	}
433
434	static __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(now: cycles, last: tkr->cycle_last, mask: tkr->mask);
439	return timekeeping_delta_to_ns(tkr, delta);
440	}
441
442	static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
443	{
444	struct tk_read_base *tkr;
445	unsigned int seq;
446	u64 now;
447
448	do {
449	seq = raw_read_seqcount_latch(s: &tkf->seq);
450	tkr = tkf->base + (seq & 0x01);
451	now = ktime_to_ns(kt: tkr->base);
452	now += fast_tk_get_delta_ns(tkr);
453	} while (raw_read_seqcount_latch_retry(s: &tkf->seq, start: seq));
454
455	return now;
456	}
457
458	/**
459	* ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
460	*
461	* This timestamp is not guaranteed to be monotonic across an update.
462	* The timestamp is calculated by:
463	*
464	* now = base_mono + clock_delta * slope
465	*
466	* So if the update lowers the slope, readers who are forced to the
467	* not yet updated second array are still using the old steeper slope.
468	*
469	* tmono
470	* ^
471	* | o n
472	* | o n
473	* | u
474	* | o
475	* |o
476	* |12345678---> reader order
477	*
478	* o = old slope
479	* u = update
480	* n = new slope
481	*
482	* So reader 6 will observe time going backwards versus reader 5.
483	*
484	* While other CPUs are likely to be able to observe that, the only way
485	* for a CPU local observation is when an NMI hits in the middle of
486	* the update. Timestamps taken from that NMI context might be ahead
487	* of the following timestamps. Callers need to be aware of that and
488	* deal with it.
489	*/
490	u64 notrace ktime_get_mono_fast_ns(void)
491	{
492	return __ktime_get_fast_ns(tkf: &tk_fast_mono);
493	}
494	EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
495
496	/**
497	* ktime_get_raw_fast_ns - Fast NMI safe access to clock monotonic raw
498	*
499	* Contrary to ktime_get_mono_fast_ns() this is always correct because the
500	* conversion factor is not affected by NTP/PTP correction.
501	*/
502	u64 notrace ktime_get_raw_fast_ns(void)
503	{
504	return __ktime_get_fast_ns(tkf: &tk_fast_raw);
505	}
506	EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
507
508	/**
509	* ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
510	*
511	* To keep it NMI safe since we're accessing from tracing, we're not using a
512	* separate timekeeper with updates to monotonic clock and boot offset
513	* protected with seqcounts. This has the following minor side effects:
514	*
515	* (1) Its possible that a timestamp be taken after the boot offset is updated
516	* but before the timekeeper is updated. If this happens, the new boot offset
517	* is added to the old timekeeping making the clock appear to update slightly
518	* earlier:
519	* CPU 0 CPU 1
520	* timekeeping_inject_sleeptime64()
521	* __timekeeping_inject_sleeptime(tk, delta);
522	* timestamp();
523	* timekeeping_update(tk, TK_CLEAR_NTP...);
524	*
525	* (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
526	* partially updated. Since the tk->offs_boot update is a rare event, this
527	* should be a rare occurrence which postprocessing should be able to handle.
528	*
529	* The caveats vs. timestamp ordering as documented for ktime_get_mono_fast_ns()
530	* apply as well.
531	*/
532	u64 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	}
538	EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
539
540	/**
541	* ktime_get_tai_fast_ns - NMI safe and fast access to tai clock.
542	*
543	* The same limitations as described for ktime_get_boot_fast_ns() apply. The
544	* mono time and the TAI offset are not read atomically which may yield wrong
545	* readouts. However, an update of the TAI offset is an rare event e.g., caused
546	* by settime or adjtimex with an offset. The user of this function has to deal
547	* with the possibility of wrong timestamps in post processing.
548	*/
549	u64 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	}
555	EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns);
556
557	static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono)
558	{
559	struct tk_read_base *tkr;
560	u64 basem, baser, delta;
561	unsigned int seq;
562
563	do {
564	seq = raw_read_seqcount_latch(s: &tkf->seq);
565	tkr = tkf->base + (seq & 0x01);
566	basem = ktime_to_ns(kt: tkr->base);
567	baser = ktime_to_ns(kt: tkr->base_real);
568	delta = fast_tk_get_delta_ns(tkr);
569	} while (raw_read_seqcount_latch_retry(s: &tkf->seq, start: 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	*/
581	u64 ktime_get_real_fast_ns(void)
582	{
583	return __ktime_get_real_fast(tkf: &tk_fast_mono, NULL);
584	}
585	EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
586
587	/**
588	* ktime_get_fast_timestamps: - NMI safe timestamps
589	* @snapshot: Pointer to timestamp storage
590	*
591	* Stores clock monotonic, boottime and realtime timestamps.
592	*
593	* Boot time is a racy access on 32bit systems if the sleep time injection
594	* happens late during resume and not in timekeeping_resume(). That could
595	* be avoided by expanding struct tk_read_base with boot offset for 32bit
596	* and adding more overhead to the update. As this is a hard to observe
597	* once per resume event which can be filtered with reasonable effort using
598	* the accurate mono/real timestamps, it's probably not worth the trouble.
599	*
600	* Aside of that it might be possible on 32 and 64 bit to observe the
601	* following when the sleep time injection happens late:
602	*
603	* CPU 0 CPU 1
604	* timekeeping_resume()
605	* ktime_get_fast_timestamps()
606	* mono, real = __ktime_get_real_fast()
607	* inject_sleep_time()
608	* update boot offset
609	* boot = mono + bootoffset;
610	*
611	* That means that boot time already has the sleep time adjustment, but
612	* real time does not. On the next readout both are in sync again.
613	*
614	* Preventing this for 64bit is not really feasible without destroying the
615	* careful cache layout of the timekeeper because the sequence count and
616	* struct tk_read_base would then need two cache lines instead of one.
617	*
618	* Access to the time keeper clock source is disabled across the innermost
619	* steps of suspend/resume. The accessors still work, but the timestamps
620	* are frozen until time keeping is resumed which happens very early.
621	*
622	* For regular suspend/resume there is no observable difference vs. sched
623	* clock, but it might affect some of the nasty low level debug printks.
624	*
625	* OTOH, access to sched clock is not guaranteed across suspend/resume on
626	* all systems either so it depends on the hardware in use.
627	*
628	* If that turns out to be a real problem then this could be mitigated by
629	* using sched clock in a similar way as during early boot. But it's not as
630	* trivial as on early boot because it needs some careful protection
631	* against the clock monotonic timestamp jumping backwards on resume.
632	*/
633	void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot)
634	{
635	struct timekeeper *tk = &tk_core.timekeeper;
636
637	snapshot->real = __ktime_get_real_fast(tkf: &tk_fast_mono, 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	*/
651	static 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: &tkr_dummy, tkf: &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: &tkr_dummy, tkf: &tk_fast_raw);
666	}
667
668	static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
669
670	static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
671	{
672	raw_notifier_call_chain(nh: &pvclock_gtod_chain, val: was_set, v: tk);
673	}
674
675	/**
676	* pvclock_gtod_register_notifier - register a pvclock timedata update listener
677	* @nb: Pointer to the notifier block to register
678	*/
679	int 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(nh: &pvclock_gtod_chain, nb);
687	update_pvclock_gtod(tk, was_set: true);
688	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
689
690	return ret;
691	}
692	EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
693
694	/**
695	* pvclock_gtod_unregister_notifier - unregister a pvclock
696	* timedata update listener
697	* @nb: Pointer to the notifier block to unregister
698	*/
699	int 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(nh: &pvclock_gtod_chain, nb);
706	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
707
708	return ret;
709	}
710	EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
711
712	/*
713	* tk_update_leap_state - helper to update the next_leap_ktime
714	*/
715	static inline void tk_update_leap_state(struct timekeeper *tk)
716	{
717	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	*/
726	static inline void tk_update_ktime_data(struct timekeeper *tk)
727	{
728	u64 seconds;
729	u32 nsec;
730
731	/*
732	* The xtime based monotonic readout is:
733	* nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
734	* The ktime based monotonic readout is:
735	* nsec = base_mono + now();
736	* ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
737	*/
738	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(ns: 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(ns: tk->raw_sec * NSEC_PER_SEC);
754	}
755
756	/* must hold timekeeper_lock */
757	static 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, was_set: action & TK_CLOCK_WAS_SET);
769
770	tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
771	update_fast_timekeeper(tkr: &tk->tkr_mono, tkf: &tk_fast_mono);
772	update_fast_timekeeper(tkr: &tk->tkr_raw, tkf: &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	*/
794	static void timekeeping_forward_now(struct timekeeper *tk)
795	{
796	u64 cycle_now, delta;
797
798	cycle_now = tk_clock_read(tkr: &tk->tkr_mono);
799	delta = clocksource_delta(now: cycle_now, last: tk->tkr_mono.cycle_last, mask: 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	*/
815	void 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(tkr: &tk->tkr_mono);
828
829	} while (read_seqcount_retry(&tk_core.seq, seq));
830
831	ts->tv_nsec = 0;
832	timespec64_add_ns(a: ts, ns: nsecs);
833	}
834	EXPORT_SYMBOL(ktime_get_real_ts64);
835
836	ktime_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(tkr: &tk->tkr_mono);
849
850	} while (read_seqcount_retry(&tk_core.seq, seq));
851
852	return ktime_add_ns(base, nsecs);
853	}
854	EXPORT_SYMBOL_GPL(ktime_get);
855
856	u32 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	}
871	EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
872
873	static ktime_t *offsets[TK_OFFS_MAX] = {
874	[TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
875	[TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
876	[TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
877	};
878
879	ktime_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(tkr: &tk->tkr_mono);
892
893	} while (read_seqcount_retry(&tk_core.seq, seq));
894
895	return ktime_add_ns(base, nsecs);
896
897	}
898	EXPORT_SYMBOL_GPL(ktime_get_with_offset);
899
900	ktime_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	}
918	EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
919
920	/**
921	* ktime_mono_to_any() - convert monotonic time to any other time
922	* @tmono: time to convert.
923	* @offs: which offset to use
924	*/
925	ktime_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	}
938	EXPORT_SYMBOL_GPL(ktime_mono_to_any);
939
940	/**
941	* ktime_get_raw - Returns the raw monotonic time in ktime_t format
942	*/
943	ktime_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(tkr: &tk->tkr_raw);
954
955	} while (read_seqcount_retry(&tk_core.seq, seq));
956
957	return ktime_add_ns(base, nsecs);
958	}
959	EXPORT_SYMBOL_GPL(ktime_get_raw);
960
961	/**
962	* ktime_get_ts64 - get the monotonic clock in timespec64 format
963	* @ts: pointer to timespec variable
964	*
965	* The function calculates the monotonic clock from the realtime
966	* clock and the wall_to_monotonic offset and stores the result
967	* in normalized timespec64 format in the variable pointed to by @ts.
968	*/
969	void 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(tkr: &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(a: ts, ns: nsec + tomono.tv_nsec);
989	}
990	EXPORT_SYMBOL_GPL(ktime_get_ts64);
991
992	/**
993	* ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
994	*
995	* Returns the seconds portion of CLOCK_MONOTONIC with a single non
996	* serialized read. tk->ktime_sec is of type 'unsigned long' so this
997	* works on both 32 and 64 bit systems. On 32 bit systems the readout
998	* covers ~136 years of uptime which should be enough to prevent
999	* premature wrap arounds.
1000	*/
1001	time64_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	}
1008	EXPORT_SYMBOL_GPL(ktime_get_seconds);
1009
1010	/**
1011	* ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
1012	*
1013	* Returns the wall clock seconds since 1970.
1014	*
1015	* For 64bit systems the fast access to tk->xtime_sec is preserved. On
1016	* 32bit systems the access must be protected with the sequence
1017	* counter to provide "atomic" access to the 64bit tk->xtime_sec
1018	* value.
1019	*/
1020	time64_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	}
1037	EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
1038
1039	/**
1040	* __ktime_get_real_seconds - The same as ktime_get_real_seconds
1041	* but without the sequence counter protect. This internal function
1042	* is called just when timekeeping lock is already held.
1043	*/
1044	noinstr 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	*/
1055	void 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(tkr: &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(tkr: &tk->tkr_mono, cycles: now);
1077	nsec_raw = timekeeping_cycles_to_ns(tkr: &tk->tkr_raw, cycles: 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	}
1084	EXPORT_SYMBOL_GPL(ktime_get_snapshot);
1085
1086	/* Scale base by mult/div checking for overflow */
1087	static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1088	{
1089	u64 tmp, rem;
1090
1091	tmp = div64_u64_rem(dividend: *base, divisor: div, remainder: &rem);
1092
1093	if (((int)sizeof(u64)*8 - fls64(x: mult) < fls64(x: tmp)) ||
1094	((int)sizeof(u64)*8 - fls64(x: mult) < fls64(x: rem)))
1095	return -EOVERFLOW;
1096	tmp *= mult;
1097
1098	rem = div64_u64(dividend: rem * mult, divisor: 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	*/
1120	static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1121	u64 partial_history_cycles,
1122	u64 total_history_cycles,
1123	bool discontinuity,
1124	struct system_device_crosststamp *ts)
1125	{
1126	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(mult: partial_history_cycles,
1147	div: total_history_cycles, base: &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	(a: corr_raw, mul: tk->tkr_mono.mult, div: 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(mult: partial_history_cycles,
1165	div: total_history_cycles, base: &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	* cycle_between - true if test occurs chronologically between before and after
1184	*/
1185	static bool cycle_between(u64 before, u64 test, u64 after)
1186	{
1187	if (test > before && test < after)
1188	return true;
1189	if (test < before && before > after)
1190	return true;
1191	return false;
1192	}
1193
1194	/**
1195	* get_device_system_crosststamp - Synchronously capture system/device timestamp
1196	* @get_time_fn: Callback to get simultaneous device time and
1197	* system counter from the device driver
1198	* @ctx: Context passed to get_time_fn()
1199	* @history_begin: Historical reference point used to interpolate system
1200	* time when counter provided by the driver is before the current interval
1201	* @xtstamp: Receives simultaneously captured system and device time
1202	*
1203	* Reads a timestamp from a device and correlates it to system time
1204	*/
1205	int get_device_system_crosststamp(int (*get_time_fn)
1206	(ktime_t *device_time,
1207	struct system_counterval_t *sys_counterval,
1208	void *ctx),
1209	void *ctx,
1210	struct system_time_snapshot *history_begin,
1211	struct system_device_crosststamp *xtstamp)
1212	{
1213	struct system_counterval_t system_counterval;
1214	struct timekeeper *tk = &tk_core.timekeeper;
1215	u64 cycles, now, interval_start;
1216	unsigned int clock_was_set_seq = 0;
1217	ktime_t base_real, base_raw;
1218	u64 nsec_real, nsec_raw;
1219	u8 cs_was_changed_seq;
1220	unsigned int seq;
1221	bool do_interp;
1222	int ret;
1223
1224	do {
1225	seq = read_seqcount_begin(&tk_core.seq);
1226	/*
1227	* Try to synchronously capture device time and a system
1228	* counter value calling back into the device driver
1229	*/
1230	ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1231	if (ret)
1232	return ret;
1233
1234	/*
1235	* Verify that the clocksource associated with the captured
1236	* system counter value is the same as the currently installed
1237	* timekeeper clocksource
1238	*/
1239	if (tk->tkr_mono.clock != system_counterval.cs)
1240	return -ENODEV;
1241	cycles = system_counterval.cycles;
1242
1243	/*
1244	* Check whether the system counter value provided by the
1245	* device driver is on the current timekeeping interval.
1246	*/
1247	now = tk_clock_read(tkr: &tk->tkr_mono);
1248	interval_start = tk->tkr_mono.cycle_last;
1249	if (!cycle_between(before: interval_start, test: cycles, after: now)) {
1250	clock_was_set_seq = tk->clock_was_set_seq;
1251	cs_was_changed_seq = tk->cs_was_changed_seq;
1252	cycles = interval_start;
1253	do_interp = true;
1254	} else {
1255	do_interp = false;
1256	}
1257
1258	base_real = ktime_add(tk->tkr_mono.base,
1259	tk_core.timekeeper.offs_real);
1260	base_raw = tk->tkr_raw.base;
1261
1262	nsec_real = timekeeping_cycles_to_ns(tkr: &tk->tkr_mono,
1263	cycles: system_counterval.cycles);
1264	nsec_raw = timekeeping_cycles_to_ns(tkr: &tk->tkr_raw,
1265	cycles: system_counterval.cycles);
1266	} while (read_seqcount_retry(&tk_core.seq, seq));
1267
1268	xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1269	xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1270
1271	/*
1272	* Interpolate if necessary, adjusting back from the start of the
1273	* current interval
1274	*/
1275	if (do_interp) {
1276	u64 partial_history_cycles, total_history_cycles;
1277	bool discontinuity;
1278
1279	/*
1280	* Check that the counter value occurs after the provided
1281	* history reference and that the history doesn't cross a
1282	* clocksource change
1283	*/
1284	if (!history_begin ||
1285	!cycle_between(before: history_begin->cycles,
1286	test: system_counterval.cycles, after: cycles) ||
1287	history_begin->cs_was_changed_seq != cs_was_changed_seq)
1288	return -EINVAL;
1289	partial_history_cycles = cycles - system_counterval.cycles;
1290	total_history_cycles = cycles - history_begin->cycles;
1291	discontinuity =
1292	history_begin->clock_was_set_seq != clock_was_set_seq;
1293
1294	ret = adjust_historical_crosststamp(history: history_begin,
1295	partial_history_cycles,
1296	total_history_cycles,
1297	discontinuity, ts: xtstamp);
1298	if (ret)
1299	return ret;
1300	}
1301
1302	return 0;
1303	}
1304	EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1305
1306	/**
1307	* do_settimeofday64 - Sets the time of day.
1308	* @ts: pointer to the timespec64 variable containing the new time
1309	*
1310	* Sets the time of day to the new time and update NTP and notify hrtimers
1311	*/
1312	int do_settimeofday64(const struct timespec64 *ts)
1313	{
1314	struct timekeeper *tk = &tk_core.timekeeper;
1315	struct timespec64 ts_delta, xt;
1316	unsigned long flags;
1317	int ret = 0;
1318
1319	if (!timespec64_valid_settod(ts))
1320	return -EINVAL;
1321
1322	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1323	write_seqcount_begin(&tk_core.seq);
1324
1325	timekeeping_forward_now(tk);
1326
1327	xt = tk_xtime(tk);
1328	ts_delta = timespec64_sub(lhs: *ts, rhs: xt);
1329
1330	if (timespec64_compare(lhs: &tk->wall_to_monotonic, rhs: &ts_delta) > 0) {
1331	ret = -EINVAL;
1332	goto out;
1333	}
1334
1335	tk_set_wall_to_mono(tk, wtm: timespec64_sub(lhs: tk->wall_to_monotonic, rhs: ts_delta));
1336
1337	tk_set_xtime(tk, ts);
1338	out:
1339	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1340
1341	write_seqcount_end(&tk_core.seq);
1342	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1343
1344	/* Signal hrtimers about time change */
1345	clock_was_set(CLOCK_SET_WALL);
1346
1347	if (!ret) {
1348	audit_tk_injoffset(offset: ts_delta);
1349	add_device_randomness(buf: ts, len: sizeof(*ts));
1350	}
1351
1352	return ret;
1353	}
1354	EXPORT_SYMBOL(do_settimeofday64);
1355
1356	/**
1357	* timekeeping_inject_offset - Adds or subtracts from the current time.
1358	* @ts: Pointer to the timespec variable containing the offset
1359	*
1360	* Adds or subtracts an offset value from the current time.
1361	*/
1362	static int timekeeping_inject_offset(const struct timespec64 *ts)
1363	{
1364	struct timekeeper *tk = &tk_core.timekeeper;
1365	unsigned long flags;
1366	struct timespec64 tmp;
1367	int ret = 0;
1368
1369	if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1370	return -EINVAL;
1371
1372	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1373	write_seqcount_begin(&tk_core.seq);
1374
1375	timekeeping_forward_now(tk);
1376
1377	/* Make sure the proposed value is valid */
1378	tmp = timespec64_add(lhs: tk_xtime(tk), rhs: *ts);
1379	if (timespec64_compare(lhs: &tk->wall_to_monotonic, rhs: ts) > 0 ||
1380	!timespec64_valid_settod(ts: &tmp)) {
1381	ret = -EINVAL;
1382	goto error;
1383	}
1384
1385	tk_xtime_add(tk, ts);
1386	tk_set_wall_to_mono(tk, wtm: timespec64_sub(lhs: tk->wall_to_monotonic, rhs: *ts));
1387
1388	error: /* even if we error out, we forwarded the time, so call update */
1389	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1390
1391	write_seqcount_end(&tk_core.seq);
1392	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1393
1394	/* Signal hrtimers about time change */
1395	clock_was_set(CLOCK_SET_WALL);
1396
1397	return ret;
1398	}
1399
1400	/*
1401	* Indicates if there is an offset between the system clock and the hardware
1402	* clock/persistent clock/rtc.
1403	*/
1404	int persistent_clock_is_local;
1405
1406	/*
1407	* Adjust the time obtained from the CMOS to be UTC time instead of
1408	* local time.
1409	*
1410	* This is ugly, but preferable to the alternatives. Otherwise we
1411	* would either need to write a program to do it in /etc/rc (and risk
1412	* confusion if the program gets run more than once; it would also be
1413	* hard to make the program warp the clock precisely n hours) or
1414	* compile in the timezone information into the kernel. Bad, bad....
1415	*
1416	* - TYT, 1992-01-01
1417	*
1418	* The best thing to do is to keep the CMOS clock in universal time (UTC)
1419	* as real UNIX machines always do it. This avoids all headaches about
1420	* daylight saving times and warping kernel clocks.
1421	*/
1422	void timekeeping_warp_clock(void)
1423	{
1424	if (sys_tz.tz_minuteswest != 0) {
1425	struct timespec64 adjust;
1426
1427	persistent_clock_is_local = 1;
1428	adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1429	adjust.tv_nsec = 0;
1430	timekeeping_inject_offset(ts: &adjust);
1431	}
1432	}
1433
1434	/*
1435	* __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1436	*/
1437	static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1438	{
1439	tk->tai_offset = tai_offset;
1440	tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1441	}
1442
1443	/*
1444	* change_clocksource - Swaps clocksources if a new one is available
1445	*
1446	* Accumulates current time interval and initializes new clocksource
1447	*/
1448	static int change_clocksource(void *data)
1449	{
1450	struct timekeeper *tk = &tk_core.timekeeper;
1451	struct clocksource *new, *old = NULL;
1452	unsigned long flags;
1453	bool change = false;
1454
1455	new = (struct clocksource *) data;
1456
1457	/*
1458	* If the cs is in module, get a module reference. Succeeds
1459	* for built-in code (owner == NULL) as well.
1460	*/
1461	if (try_module_get(module: new->owner)) {
1462	if (!new->enable || new->enable(new) == 0)
1463	change = true;
1464	else
1465	module_put(module: new->owner);
1466	}
1467
1468	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1469	write_seqcount_begin(&tk_core.seq);
1470
1471	timekeeping_forward_now(tk);
1472
1473	if (change) {
1474	old = tk->tkr_mono.clock;
1475	tk_setup_internals(tk, clock: new);
1476	}
1477
1478	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1479
1480	write_seqcount_end(&tk_core.seq);
1481	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1482
1483	if (old) {
1484	if (old->disable)
1485	old->disable(old);
1486
1487	module_put(module: old->owner);
1488	}
1489
1490	return 0;
1491	}
1492
1493	/**
1494	* timekeeping_notify - Install a new clock source
1495	* @clock: pointer to the clock source
1496	*
1497	* This function is called from clocksource.c after a new, better clock
1498	* source has been registered. The caller holds the clocksource_mutex.
1499	*/
1500	int timekeeping_notify(struct clocksource *clock)
1501	{
1502	struct timekeeper *tk = &tk_core.timekeeper;
1503
1504	if (tk->tkr_mono.clock == clock)
1505	return 0;
1506	stop_machine(fn: change_clocksource, data: clock, NULL);
1507	tick_clock_notify();
1508	return tk->tkr_mono.clock == clock ? 0 : -1;
1509	}
1510
1511	/**
1512	* ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1513	* @ts: pointer to the timespec64 to be set
1514	*
1515	* Returns the raw monotonic time (completely un-modified by ntp)
1516	*/
1517	void ktime_get_raw_ts64(struct timespec64 *ts)
1518	{
1519	struct timekeeper *tk = &tk_core.timekeeper;
1520	unsigned int seq;
1521	u64 nsecs;
1522
1523	do {
1524	seq = read_seqcount_begin(&tk_core.seq);
1525	ts->tv_sec = tk->raw_sec;
1526	nsecs = timekeeping_get_ns(tkr: &tk->tkr_raw);
1527
1528	} while (read_seqcount_retry(&tk_core.seq, seq));
1529
1530	ts->tv_nsec = 0;
1531	timespec64_add_ns(a: ts, ns: nsecs);
1532	}
1533	EXPORT_SYMBOL(ktime_get_raw_ts64);
1534
1535
1536	/**
1537	* timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1538	*/
1539	int timekeeping_valid_for_hres(void)
1540	{
1541	struct timekeeper *tk = &tk_core.timekeeper;
1542	unsigned int seq;
1543	int ret;
1544
1545	do {
1546	seq = read_seqcount_begin(&tk_core.seq);
1547
1548	ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1549
1550	} while (read_seqcount_retry(&tk_core.seq, seq));
1551
1552	return ret;
1553	}
1554
1555	/**
1556	* timekeeping_max_deferment - Returns max time the clocksource can be deferred
1557	*/
1558	u64 timekeeping_max_deferment(void)
1559	{
1560	struct timekeeper *tk = &tk_core.timekeeper;
1561	unsigned int seq;
1562	u64 ret;
1563
1564	do {
1565	seq = read_seqcount_begin(&tk_core.seq);
1566
1567	ret = tk->tkr_mono.clock->max_idle_ns;
1568
1569	} while (read_seqcount_retry(&tk_core.seq, seq));
1570
1571	return ret;
1572	}
1573
1574	/**
1575	* read_persistent_clock64 - Return time from the persistent clock.
1576	* @ts: Pointer to the storage for the readout value
1577	*
1578	* Weak dummy function for arches that do not yet support it.
1579	* Reads the time from the battery backed persistent clock.
1580	* Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1581	*
1582	* XXX - Do be sure to remove it once all arches implement it.
1583	*/
1584	void __weak read_persistent_clock64(struct timespec64 *ts)
1585	{
1586	ts->tv_sec = 0;
1587	ts->tv_nsec = 0;
1588	}
1589
1590	/**
1591	* read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1592	* from the boot.
1593	* @wall_time: current time as returned by persistent clock
1594	* @boot_offset: offset that is defined as wall_time - boot_time
1595	*
1596	* Weak dummy function for arches that do not yet support it.
1597	*
1598	* The default function calculates offset based on the current value of
1599	* local_clock(). This way architectures that support sched_clock() but don't
1600	* support dedicated boot time clock will provide the best estimate of the
1601	* boot time.
1602	*/
1603	void __weak __init
1604	read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1605	struct timespec64 *boot_offset)
1606	{
1607	read_persistent_clock64(ts: wall_time);
1608	*boot_offset = ns_to_timespec64(nsec: local_clock());
1609	}
1610
1611	/*
1612	* Flag reflecting whether timekeeping_resume() has injected sleeptime.
1613	*
1614	* The flag starts of false and is only set when a suspend reaches
1615	* timekeeping_suspend(), timekeeping_resume() sets it to false when the
1616	* timekeeper clocksource is not stopping across suspend and has been
1617	* used to update sleep time. If the timekeeper clocksource has stopped
1618	* then the flag stays true and is used by the RTC resume code to decide
1619	* whether sleeptime must be injected and if so the flag gets false then.
1620	*
1621	* If a suspend fails before reaching timekeeping_resume() then the flag
1622	* stays false and prevents erroneous sleeptime injection.
1623	*/
1624	static bool suspend_timing_needed;
1625
1626	/* Flag for if there is a persistent clock on this platform */
1627	static bool persistent_clock_exists;
1628
1629	/*
1630	* timekeeping_init - Initializes the clocksource and common timekeeping values
1631	*/
1632	void __init timekeeping_init(void)
1633	{
1634	struct timespec64 wall_time, boot_offset, wall_to_mono;
1635	struct timekeeper *tk = &tk_core.timekeeper;
1636	struct clocksource *clock;
1637	unsigned long flags;
1638
1639	read_persistent_wall_and_boot_offset(wall_time: &wall_time, boot_offset: &boot_offset);
1640	if (timespec64_valid_settod(ts: &wall_time) &&
1641	timespec64_to_ns(ts: &wall_time) > 0) {
1642	persistent_clock_exists = true;
1643	} else if (timespec64_to_ns(ts: &wall_time) != 0) {
1644	pr_warn("Persistent clock returned invalid value");
1645	wall_time = (struct timespec64){0};
1646	}
1647
1648	if (timespec64_compare(&wall_time, &boot_offset) < 0)
1649	boot_offset = (struct timespec64){0};
1650
1651	/*
1652	* We want set wall_to_mono, so the following is true:
1653	* wall time + wall_to_mono = boot time
1654	*/
1655	wall_to_mono = timespec64_sub(boot_offset, wall_time);
1656
1657	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1658	write_seqcount_begin(&tk_core.seq);
1659	ntp_init();
1660
1661	clock = clocksource_default_clock();
1662	if (clock->enable)
1663	clock->enable(clock);
1664	tk_setup_internals(tk, clock);
1665
1666	tk_set_xtime(tk, &wall_time);
1667	tk->raw_sec = 0;
1668
1669	tk_set_wall_to_mono(tk, wall_to_mono);
1670
1671	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1672
1673	write_seqcount_end(&tk_core.seq);
1674	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1675	}
1676
1677	/* time in seconds when suspend began for persistent clock */
1678	static struct timespec64 timekeeping_suspend_time;
1679
1680	/**
1681	* __timekeeping_inject_sleeptime - Internal function to add sleep interval
1682	* @tk: Pointer to the timekeeper to be updated
1683	* @delta: Pointer to the delta value in timespec64 format
1684	*
1685	* Takes a timespec offset measuring a suspend interval and properly
1686	* adds the sleep offset to the timekeeping variables.
1687	*/
1688	static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1689	const struct timespec64 *delta)
1690	{
1691	if (!timespec64_valid_strict(ts: delta)) {
1692	printk_deferred(KERN_WARNING
1693	"__timekeeping_inject_sleeptime: Invalid "
1694	"sleep delta value!\n");
1695	return;
1696	}
1697	tk_xtime_add(tk, ts: delta);
1698	tk_set_wall_to_mono(tk, wtm: timespec64_sub(lhs: tk->wall_to_monotonic, rhs: *delta));
1699	tk_update_sleep_time(tk, delta: timespec64_to_ktime(ts: *delta));
1700	tk_debug_account_sleep_time(t: delta);
1701	}
1702
1703	#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1704	/*
1705	* We have three kinds of time sources to use for sleep time
1706	* injection, the preference order is:
1707	* 1) non-stop clocksource
1708	* 2) persistent clock (ie: RTC accessible when irqs are off)
1709	* 3) RTC
1710	*
1711	* 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1712	* If system has neither 1) nor 2), 3) will be used finally.
1713	*
1714	*
1715	* If timekeeping has injected sleeptime via either 1) or 2),
1716	* 3) becomes needless, so in this case we don't need to call
1717	* rtc_resume(), and this is what timekeeping_rtc_skipresume()
1718	* means.
1719	*/
1720	bool timekeeping_rtc_skipresume(void)
1721	{
1722	return !suspend_timing_needed;
1723	}
1724
1725	/*
1726	* 1) can be determined whether to use or not only when doing
1727	* timekeeping_resume() which is invoked after rtc_suspend(),
1728	* so we can't skip rtc_suspend() surely if system has 1).
1729	*
1730	* But if system has 2), 2) will definitely be used, so in this
1731	* case we don't need to call rtc_suspend(), and this is what
1732	* timekeeping_rtc_skipsuspend() means.
1733	*/
1734	bool timekeeping_rtc_skipsuspend(void)
1735	{
1736	return persistent_clock_exists;
1737	}
1738
1739	/**
1740	* timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1741	* @delta: pointer to a timespec64 delta value
1742	*
1743	* This hook is for architectures that cannot support read_persistent_clock64
1744	* because their RTC/persistent clock is only accessible when irqs are enabled.
1745	* and also don't have an effective nonstop clocksource.
1746	*
1747	* This function should only be called by rtc_resume(), and allows
1748	* a suspend offset to be injected into the timekeeping values.
1749	*/
1750	void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1751	{
1752	struct timekeeper *tk = &tk_core.timekeeper;
1753	unsigned long flags;
1754
1755	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1756	write_seqcount_begin(&tk_core.seq);
1757
1758	suspend_timing_needed = false;
1759
1760	timekeeping_forward_now(tk);
1761
1762	__timekeeping_inject_sleeptime(tk, delta);
1763
1764	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1765
1766	write_seqcount_end(&tk_core.seq);
1767	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1768
1769	/* Signal hrtimers about time change */
1770	clock_was_set(CLOCK_SET_WALL | CLOCK_SET_BOOT);
1771	}
1772	#endif
1773
1774	/**
1775	* timekeeping_resume - Resumes the generic timekeeping subsystem.
1776	*/
1777	void timekeeping_resume(void)
1778	{
1779	struct timekeeper *tk = &tk_core.timekeeper;
1780	struct clocksource *clock = tk->tkr_mono.clock;
1781	unsigned long flags;
1782	struct timespec64 ts_new, ts_delta;
1783	u64 cycle_now, nsec;
1784	bool inject_sleeptime = false;
1785
1786	read_persistent_clock64(ts: &ts_new);
1787
1788	clockevents_resume();
1789	clocksource_resume();
1790
1791	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1792	write_seqcount_begin(&tk_core.seq);
1793
1794	/*
1795	* After system resumes, we need to calculate the suspended time and
1796	* compensate it for the OS time. There are 3 sources that could be
1797	* used: Nonstop clocksource during suspend, persistent clock and rtc
1798	* device.
1799	*
1800	* One specific platform may have 1 or 2 or all of them, and the
1801	* preference will be:
1802	* suspend-nonstop clocksource -> persistent clock -> rtc
1803	* The less preferred source will only be tried if there is no better
1804	* usable source. The rtc part is handled separately in rtc core code.
1805	*/
1806	cycle_now = tk_clock_read(tkr: &tk->tkr_mono);
1807	nsec = clocksource_stop_suspend_timing(cs: clock, now: cycle_now);
1808	if (nsec > 0) {
1809	ts_delta = ns_to_timespec64(nsec);
1810	inject_sleeptime = true;
1811	} else if (timespec64_compare(lhs: &ts_new, rhs: &timekeeping_suspend_time) > 0) {
1812	ts_delta = timespec64_sub(lhs: ts_new, rhs: timekeeping_suspend_time);
1813	inject_sleeptime = true;
1814	}
1815
1816	if (inject_sleeptime) {
1817	suspend_timing_needed = false;
1818	__timekeeping_inject_sleeptime(tk, delta: &ts_delta);
1819	}
1820
1821	/* Re-base the last cycle value */
1822	tk->tkr_mono.cycle_last = cycle_now;
1823	tk->tkr_raw.cycle_last = cycle_now;
1824
1825	tk->ntp_error = 0;
1826	timekeeping_suspended = 0;
1827	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1828	write_seqcount_end(&tk_core.seq);
1829	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1830
1831	touch_softlockup_watchdog();
1832
1833	/* Resume the clockevent device(s) and hrtimers */
1834	tick_resume();
1835	/* Notify timerfd as resume is equivalent to clock_was_set() */
1836	timerfd_resume();
1837	}
1838
1839	int timekeeping_suspend(void)
1840	{
1841	struct timekeeper *tk = &tk_core.timekeeper;
1842	unsigned long flags;
1843	struct timespec64 delta, delta_delta;
1844	static struct timespec64 old_delta;
1845	struct clocksource *curr_clock;
1846	u64 cycle_now;
1847
1848	read_persistent_clock64(ts: &timekeeping_suspend_time);
1849
1850	/*
1851	* On some systems the persistent_clock can not be detected at
1852	* timekeeping_init by its return value, so if we see a valid
1853	* value returned, update the persistent_clock_exists flag.
1854	*/
1855	if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1856	persistent_clock_exists = true;
1857
1858	suspend_timing_needed = true;
1859
1860	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1861	write_seqcount_begin(&tk_core.seq);
1862	timekeeping_forward_now(tk);
1863	timekeeping_suspended = 1;
1864
1865	/*
1866	* Since we've called forward_now, cycle_last stores the value
1867	* just read from the current clocksource. Save this to potentially
1868	* use in suspend timing.
1869	*/
1870	curr_clock = tk->tkr_mono.clock;
1871	cycle_now = tk->tkr_mono.cycle_last;
1872	clocksource_start_suspend_timing(cs: curr_clock, start_cycles: cycle_now);
1873
1874	if (persistent_clock_exists) {
1875	/*
1876	* To avoid drift caused by repeated suspend/resumes,
1877	* which each can add ~1 second drift error,
1878	* try to compensate so the difference in system time
1879	* and persistent_clock time stays close to constant.
1880	*/
1881	delta = timespec64_sub(lhs: tk_xtime(tk), rhs: timekeeping_suspend_time);
1882	delta_delta = timespec64_sub(lhs: delta, rhs: old_delta);
1883	if (abs(delta_delta.tv_sec) >= 2) {
1884	/*
1885	* if delta_delta is too large, assume time correction
1886	* has occurred and set old_delta to the current delta.
1887	*/
1888	old_delta = delta;
1889	} else {
1890	/* Otherwise try to adjust old_system to compensate */
1891	timekeeping_suspend_time =
1892	timespec64_add(lhs: timekeeping_suspend_time, rhs: delta_delta);
1893	}
1894	}
1895
1896	timekeeping_update(tk, TK_MIRROR);
1897	halt_fast_timekeeper(tk);
1898	write_seqcount_end(&tk_core.seq);
1899	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1900
1901	tick_suspend();
1902	clocksource_suspend();
1903	clockevents_suspend();
1904
1905	return 0;
1906	}
1907
1908	/* sysfs resume/suspend bits for timekeeping */
1909	static struct syscore_ops timekeeping_syscore_ops = {
1910	.resume = timekeeping_resume,
1911	.suspend = timekeeping_suspend,
1912	};
1913
1914	static int __init timekeeping_init_ops(void)
1915	{
1916	register_syscore_ops(ops: &timekeeping_syscore_ops);
1917	return 0;
1918	}
1919	device_initcall(timekeeping_init_ops);
1920
1921	/*
1922	* Apply a multiplier adjustment to the timekeeper
1923	*/
1924	static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1925	s64 offset,
1926	s32 mult_adj)
1927	{
1928	s64 interval = tk->cycle_interval;
1929
1930	if (mult_adj == 0) {
1931	return;
1932	} else if (mult_adj == -1) {
1933	interval = -interval;
1934	offset = -offset;
1935	} else if (mult_adj != 1) {
1936	interval *= mult_adj;
1937	offset *= mult_adj;
1938	}
1939
1940	/*
1941	* So the following can be confusing.
1942	*
1943	* To keep things simple, lets assume mult_adj == 1 for now.
1944	*
1945	* When mult_adj != 1, remember that the interval and offset values
1946	* have been appropriately scaled so the math is the same.
1947	*
1948	* The basic idea here is that we're increasing the multiplier
1949	* by one, this causes the xtime_interval to be incremented by
1950	* one cycle_interval. This is because:
1951	* xtime_interval = cycle_interval * mult
1952	* So if mult is being incremented by one:
1953	* xtime_interval = cycle_interval * (mult + 1)
1954	* Its the same as:
1955	* xtime_interval = (cycle_interval * mult) + cycle_interval
1956	* Which can be shortened to:
1957	* xtime_interval += cycle_interval
1958	*
1959	* So offset stores the non-accumulated cycles. Thus the current
1960	* time (in shifted nanoseconds) is:
1961	* now = (offset * adj) + xtime_nsec
1962	* Now, even though we're adjusting the clock frequency, we have
1963	* to keep time consistent. In other words, we can't jump back
1964	* in time, and we also want to avoid jumping forward in time.
1965	*
1966	* So given the same offset value, we need the time to be the same
1967	* both before and after the freq adjustment.
1968	* now = (offset * adj_1) + xtime_nsec_1
1969	* now = (offset * adj_2) + xtime_nsec_2
1970	* So:
1971	* (offset * adj_1) + xtime_nsec_1 =
1972	* (offset * adj_2) + xtime_nsec_2
1973	* And we know:
1974	* adj_2 = adj_1 + 1
1975	* So:
1976	* (offset * adj_1) + xtime_nsec_1 =
1977	* (offset * (adj_1+1)) + xtime_nsec_2
1978	* (offset * adj_1) + xtime_nsec_1 =
1979	* (offset * adj_1) + offset + xtime_nsec_2
1980	* Canceling the sides:
1981	* xtime_nsec_1 = offset + xtime_nsec_2
1982	* Which gives us:
1983	* xtime_nsec_2 = xtime_nsec_1 - offset
1984	* Which simplifies to:
1985	* xtime_nsec -= offset
1986	*/
1987	if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1988	/* NTP adjustment caused clocksource mult overflow */
1989	WARN_ON_ONCE(1);
1990	return;
1991	}
1992
1993	tk->tkr_mono.mult += mult_adj;
1994	tk->xtime_interval += interval;
1995	tk->tkr_mono.xtime_nsec -= offset;
1996	}
1997
1998	/*
1999	* Adjust the timekeeper's multiplier to the correct frequency
2000	* and also to reduce the accumulated error value.
2001	*/
2002	static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
2003	{
2004	u32 mult;
2005
2006	/*
2007	* Determine the multiplier from the current NTP tick length.
2008	* Avoid expensive division when the tick length doesn't change.
2009	*/
2010	if (likely(tk->ntp_tick == ntp_tick_length())) {
2011	mult = tk->tkr_mono.mult - tk->ntp_err_mult;
2012	} else {
2013	tk->ntp_tick = ntp_tick_length();
2014	mult = div64_u64(dividend: (tk->ntp_tick >> tk->ntp_error_shift) -
2015	tk->xtime_remainder, divisor: tk->cycle_interval);
2016	}
2017
2018	/*
2019	* If the clock is behind the NTP time, increase the multiplier by 1
2020	* to catch up with it. If it's ahead and there was a remainder in the
2021	* tick division, the clock will slow down. Otherwise it will stay
2022	* ahead until the tick length changes to a non-divisible value.
2023	*/
2024	tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
2025	mult += tk->ntp_err_mult;
2026
2027	timekeeping_apply_adjustment(tk, offset, mult_adj: mult - tk->tkr_mono.mult);
2028
2029	if (unlikely(tk->tkr_mono.clock->maxadj &&
2030	(abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
2031	> tk->tkr_mono.clock->maxadj))) {
2032	printk_once(KERN_WARNING
2033	"Adjusting %s more than 11%% (%ld vs %ld)\n",
2034	tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
2035	(long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
2036	}
2037
2038	/*
2039	* It may be possible that when we entered this function, xtime_nsec
2040	* was very small. Further, if we're slightly speeding the clocksource
2041	* in the code above, its possible the required corrective factor to
2042	* xtime_nsec could cause it to underflow.
2043	*
2044	* Now, since we have already accumulated the second and the NTP
2045	* subsystem has been notified via second_overflow(), we need to skip
2046	* the next update.
2047	*/
2048	if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
2049	tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
2050	tk->tkr_mono.shift;
2051	tk->xtime_sec--;
2052	tk->skip_second_overflow = 1;
2053	}
2054	}
2055
2056	/*
2057	* accumulate_nsecs_to_secs - Accumulates nsecs into secs
2058	*
2059	* Helper function that accumulates the nsecs greater than a second
2060	* from the xtime_nsec field to the xtime_secs field.
2061	* It also calls into the NTP code to handle leapsecond processing.
2062	*/
2063	static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
2064	{
2065	u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
2066	unsigned int clock_set = 0;
2067
2068	while (tk->tkr_mono.xtime_nsec >= nsecps) {
2069	int leap;
2070
2071	tk->tkr_mono.xtime_nsec -= nsecps;
2072	tk->xtime_sec++;
2073
2074	/*
2075	* Skip NTP update if this second was accumulated before,
2076	* i.e. xtime_nsec underflowed in timekeeping_adjust()
2077	*/
2078	if (unlikely(tk->skip_second_overflow)) {
2079	tk->skip_second_overflow = 0;
2080	continue;
2081	}
2082
2083	/* Figure out if its a leap sec and apply if needed */
2084	leap = second_overflow(secs: tk->xtime_sec);
2085	if (unlikely(leap)) {
2086	struct timespec64 ts;
2087
2088	tk->xtime_sec += leap;
2089
2090	ts.tv_sec = leap;
2091	ts.tv_nsec = 0;
2092	tk_set_wall_to_mono(tk,
2093	wtm: timespec64_sub(lhs: tk->wall_to_monotonic, rhs: ts));
2094
2095	__timekeeping_set_tai_offset(tk, tai_offset: tk->tai_offset - leap);
2096
2097	clock_set = TK_CLOCK_WAS_SET;
2098	}
2099	}
2100	return clock_set;
2101	}
2102
2103	/*
2104	* logarithmic_accumulation - shifted accumulation of cycles
2105	*
2106	* This functions accumulates a shifted interval of cycles into
2107	* a shifted interval nanoseconds. Allows for O(log) accumulation
2108	* loop.
2109	*
2110	* Returns the unconsumed cycles.
2111	*/
2112	static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2113	u32 shift, unsigned int *clock_set)
2114	{
2115	u64 interval = tk->cycle_interval << shift;
2116	u64 snsec_per_sec;
2117
2118	/* If the offset is smaller than a shifted interval, do nothing */
2119	if (offset < interval)
2120	return offset;
2121
2122	/* Accumulate one shifted interval */
2123	offset -= interval;
2124	tk->tkr_mono.cycle_last += interval;
2125	tk->tkr_raw.cycle_last += interval;
2126
2127	tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2128	*clock_set |= accumulate_nsecs_to_secs(tk);
2129
2130	/* Accumulate raw time */
2131	tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2132	snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2133	while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2134	tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2135	tk->raw_sec++;
2136	}
2137
2138	/* Accumulate error between NTP and clock interval */
2139	tk->ntp_error += tk->ntp_tick << shift;
2140	tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2141	(tk->ntp_error_shift + shift);
2142
2143	return offset;
2144	}
2145
2146	/*
2147	* timekeeping_advance - Updates the timekeeper to the current time and
2148	* current NTP tick length
2149	*/
2150	static bool timekeeping_advance(enum timekeeping_adv_mode mode)
2151	{
2152	struct timekeeper *real_tk = &tk_core.timekeeper;
2153	struct timekeeper *tk = &shadow_timekeeper;
2154	u64 offset;
2155	int shift = 0, maxshift;
2156	unsigned int clock_set = 0;
2157	unsigned long flags;
2158
2159	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2160
2161	/* Make sure we're fully resumed: */
2162	if (unlikely(timekeeping_suspended))
2163	goto out;
2164
2165	offset = clocksource_delta(now: tk_clock_read(tkr: &tk->tkr_mono),
2166	last: tk->tkr_mono.cycle_last, mask: tk->tkr_mono.mask);
2167
2168	/* Check if there's really nothing to do */
2169	if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2170	goto out;
2171
2172	/* Do some additional sanity checking */
2173	timekeeping_check_update(tk, offset);
2174
2175	/*
2176	* With NO_HZ we may have to accumulate many cycle_intervals
2177	* (think "ticks") worth of time at once. To do this efficiently,
2178	* we calculate the largest doubling multiple of cycle_intervals
2179	* that is smaller than the offset. We then accumulate that
2180	* chunk in one go, and then try to consume the next smaller
2181	* doubled multiple.
2182	*/
2183	shift = ilog2(offset) - ilog2(tk->cycle_interval);
2184	shift = max(0, shift);
2185	/* Bound shift to one less than what overflows tick_length */
2186	maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2187	shift = min(shift, maxshift);
2188	while (offset >= tk->cycle_interval) {
2189	offset = logarithmic_accumulation(tk, offset, shift,
2190	clock_set: &clock_set);
2191	if (offset < tk->cycle_interval<<shift)
2192	shift--;
2193	}
2194
2195	/* Adjust the multiplier to correct NTP error */
2196	timekeeping_adjust(tk, offset);
2197
2198	/*
2199	* Finally, make sure that after the rounding
2200	* xtime_nsec isn't larger than NSEC_PER_SEC
2201	*/
2202	clock_set |= accumulate_nsecs_to_secs(tk);
2203
2204	write_seqcount_begin(&tk_core.seq);
2205	/*
2206	* Update the real timekeeper.
2207	*
2208	* We could avoid this memcpy by switching pointers, but that
2209	* requires changes to all other timekeeper usage sites as
2210	* well, i.e. move the timekeeper pointer getter into the
2211	* spinlocked/seqcount protected sections. And we trade this
2212	* memcpy under the tk_core.seq against one before we start
2213	* updating.
2214	*/
2215	timekeeping_update(tk, action: clock_set);
2216	memcpy(real_tk, tk, sizeof(*tk));
2217	/* The memcpy must come last. Do not put anything here! */
2218	write_seqcount_end(&tk_core.seq);
2219	out:
2220	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2221
2222	return !!clock_set;
2223	}
2224
2225	/**
2226	* update_wall_time - Uses the current clocksource to increment the wall time
2227	*
2228	*/
2229	void update_wall_time(void)
2230	{
2231	if (timekeeping_advance(mode: TK_ADV_TICK))
2232	clock_was_set_delayed();
2233	}
2234
2235	/**
2236	* getboottime64 - Return the real time of system boot.
2237	* @ts: pointer to the timespec64 to be set
2238	*
2239	* Returns the wall-time of boot in a timespec64.
2240	*
2241	* This is based on the wall_to_monotonic offset and the total suspend
2242	* time. Calls to settimeofday will affect the value returned (which
2243	* basically means that however wrong your real time clock is at boot time,
2244	* you get the right time here).
2245	*/
2246	void getboottime64(struct timespec64 *ts)
2247	{
2248	struct timekeeper *tk = &tk_core.timekeeper;
2249	ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2250
2251	*ts = ktime_to_timespec64(t);
2252	}
2253	EXPORT_SYMBOL_GPL(getboottime64);
2254
2255	void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2256	{
2257	struct timekeeper *tk = &tk_core.timekeeper;
2258	unsigned int seq;
2259
2260	do {
2261	seq = read_seqcount_begin(&tk_core.seq);
2262
2263	*ts = tk_xtime(tk);
2264	} while (read_seqcount_retry(&tk_core.seq, seq));
2265	}
2266	EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2267
2268	void ktime_get_coarse_ts64(struct timespec64 *ts)
2269	{
2270	struct timekeeper *tk = &tk_core.timekeeper;
2271	struct timespec64 now, mono;
2272	unsigned int seq;
2273
2274	do {
2275	seq = read_seqcount_begin(&tk_core.seq);
2276
2277	now = tk_xtime(tk);
2278	mono = tk->wall_to_monotonic;
2279	} while (read_seqcount_retry(&tk_core.seq, seq));
2280
2281	set_normalized_timespec64(ts, sec: now.tv_sec + mono.tv_sec,
2282	nsec: now.tv_nsec + mono.tv_nsec);
2283	}
2284	EXPORT_SYMBOL(ktime_get_coarse_ts64);
2285
2286	/*
2287	* Must hold jiffies_lock
2288	*/
2289	void do_timer(unsigned long ticks)
2290	{
2291	jiffies_64 += ticks;
2292	calc_global_load();
2293	}
2294
2295	/**
2296	* ktime_get_update_offsets_now - hrtimer helper
2297	* @cwsseq: pointer to check and store the clock was set sequence number
2298	* @offs_real: pointer to storage for monotonic -> realtime offset
2299	* @offs_boot: pointer to storage for monotonic -> boottime offset
2300	* @offs_tai: pointer to storage for monotonic -> clock tai offset
2301	*
2302	* Returns current monotonic time and updates the offsets if the
2303	* sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2304	* different.
2305	*
2306	* Called from hrtimer_interrupt() or retrigger_next_event()
2307	*/
2308	ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2309	ktime_t *offs_boot, ktime_t *offs_tai)
2310	{
2311	struct timekeeper *tk = &tk_core.timekeeper;
2312	unsigned int seq;
2313	ktime_t base;
2314	u64 nsecs;
2315
2316	do {
2317	seq = read_seqcount_begin(&tk_core.seq);
2318
2319	base = tk->tkr_mono.base;
2320	nsecs = timekeeping_get_ns(tkr: &tk->tkr_mono);
2321	base = ktime_add_ns(base, nsecs);
2322
2323	if (*cwsseq != tk->clock_was_set_seq) {
2324	*cwsseq = tk->clock_was_set_seq;
2325	*offs_real = tk->offs_real;
2326	*offs_boot = tk->offs_boot;
2327	*offs_tai = tk->offs_tai;
2328	}
2329
2330	/* Handle leapsecond insertion adjustments */
2331	if (unlikely(base >= tk->next_leap_ktime))
2332	*offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2333
2334	} while (read_seqcount_retry(&tk_core.seq, seq));
2335
2336	return base;
2337	}
2338
2339	/*
2340	* timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2341	*/
2342	static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2343	{
2344	if (txc->modes & ADJ_ADJTIME) {
2345	/* singleshot must not be used with any other mode bits */
2346	if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2347	return -EINVAL;
2348	if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2349	!capable(CAP_SYS_TIME))
2350	return -EPERM;
2351	} else {
2352	/* In order to modify anything, you gotta be super-user! */
2353	if (txc->modes && !capable(CAP_SYS_TIME))
2354	return -EPERM;
2355	/*
2356	* if the quartz is off by more than 10% then
2357	* something is VERY wrong!
2358	*/
2359	if (txc->modes & ADJ_TICK &&
2360	(txc->tick < 900000/USER_HZ ||
2361	txc->tick > 1100000/USER_HZ))
2362	return -EINVAL;
2363	}
2364
2365	if (txc->modes & ADJ_SETOFFSET) {
2366	/* In order to inject time, you gotta be super-user! */
2367	if (!capable(CAP_SYS_TIME))
2368	return -EPERM;
2369
2370	/*
2371	* Validate if a timespec/timeval used to inject a time
2372	* offset is valid. Offsets can be positive or negative, so
2373	* we don't check tv_sec. The value of the timeval/timespec
2374	* is the sum of its fields,but *NOTE*:
2375	* The field tv_usec/tv_nsec must always be non-negative and
2376	* we can't have more nanoseconds/microseconds than a second.
2377	*/
2378	if (txc->time.tv_usec < 0)
2379	return -EINVAL;
2380
2381	if (txc->modes & ADJ_NANO) {
2382	if (txc->time.tv_usec >= NSEC_PER_SEC)
2383	return -EINVAL;
2384	} else {
2385	if (txc->time.tv_usec >= USEC_PER_SEC)
2386	return -EINVAL;
2387	}
2388	}
2389
2390	/*
2391	* Check for potential multiplication overflows that can
2392	* only happen on 64-bit systems:
2393	*/
2394	if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2395	if (LLONG_MIN / PPM_SCALE > txc->freq)
2396	return -EINVAL;
2397	if (LLONG_MAX / PPM_SCALE < txc->freq)
2398	return -EINVAL;
2399	}
2400
2401	return 0;
2402	}
2403
2404	/**
2405	* random_get_entropy_fallback - Returns the raw clock source value,
2406	* used by random.c for platforms with no valid random_get_entropy().
2407	*/
2408	unsigned long random_get_entropy_fallback(void)
2409	{
2410	struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono;
2411	struct clocksource *clock = READ_ONCE(tkr->clock);
2412
2413	if (unlikely(timekeeping_suspended || !clock))
2414	return 0;
2415	return clock->read(clock);
2416	}
2417	EXPORT_SYMBOL_GPL(random_get_entropy_fallback);
2418
2419	/**
2420	* do_adjtimex() - Accessor function to NTP __do_adjtimex function
2421	*/
2422	int do_adjtimex(struct __kernel_timex *txc)
2423	{
2424	struct timekeeper *tk = &tk_core.timekeeper;
2425	struct audit_ntp_data ad;
2426	bool clock_set = false;
2427	struct timespec64 ts;
2428	unsigned long flags;
2429	s32 orig_tai, tai;
2430	int ret;
2431
2432	/* Validate the data before disabling interrupts */
2433	ret = timekeeping_validate_timex(txc);
2434	if (ret)
2435	return ret;
2436	add_device_randomness(buf: txc, len: sizeof(*txc));
2437
2438	if (txc->modes & ADJ_SETOFFSET) {
2439	struct timespec64 delta;
2440	delta.tv_sec = txc->time.tv_sec;
2441	delta.tv_nsec = txc->time.tv_usec;
2442	if (!(txc->modes & ADJ_NANO))
2443	delta.tv_nsec *= 1000;
2444	ret = timekeeping_inject_offset(ts: &delta);
2445	if (ret)
2446	return ret;
2447
2448	audit_tk_injoffset(offset: delta);
2449	}
2450
2451	audit_ntp_init(ad: &ad);
2452
2453	ktime_get_real_ts64(&ts);
2454	add_device_randomness(buf: &ts, len: sizeof(ts));
2455
2456	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2457	write_seqcount_begin(&tk_core.seq);
2458
2459	orig_tai = tai = tk->tai_offset;
2460	ret = __do_adjtimex(txc, ts: &ts, time_tai: &tai, ad: &ad);
2461
2462	if (tai != orig_tai) {
2463	__timekeeping_set_tai_offset(tk, tai_offset: tai);
2464	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2465	clock_set = true;
2466	}
2467	tk_update_leap_state(tk);
2468
2469	write_seqcount_end(&tk_core.seq);
2470	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2471
2472	audit_ntp_log(ad: &ad);
2473
2474	/* Update the multiplier immediately if frequency was set directly */
2475	if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2476	clock_set |= timekeeping_advance(mode: TK_ADV_FREQ);
2477
2478	if (clock_set)
2479	clock_was_set(CLOCK_REALTIME);
2480
2481	ntp_notify_cmos_timer();
2482
2483	return ret;
2484	}
2485
2486	#ifdef CONFIG_NTP_PPS
2487	/**
2488	* hardpps() - Accessor function to NTP __hardpps function
2489	*/
2490	void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2491	{
2492	unsigned long flags;
2493
2494	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2495	write_seqcount_begin(&tk_core.seq);
2496
2497	__hardpps(phase_ts, raw_ts);
2498
2499	write_seqcount_end(&tk_core.seq);
2500	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2501	}
2502	EXPORT_SYMBOL(hardpps);
2503	#endif /* CONFIG_NTP_PPS */
2504