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/timekeeper_internal.h>
  12#include <linux/module.h>
  13#include <linux/interrupt.h>
  14#include <linux/percpu.h>
  15#include <linux/init.h>
  16#include <linux/mm.h>
  17#include <linux/nmi.h>
  18#include <linux/sched.h>
  19#include <linux/sched/loadavg.h>
  20#include <linux/syscore_ops.h>
  21#include <linux/clocksource.h>
  22#include <linux/jiffies.h>
  23#include <linux/time.h>
  24#include <linux/tick.h>
  25#include <linux/stop_machine.h>
  26#include <linux/pvclock_gtod.h>
  27#include <linux/compiler.h>
  28
  29#include "tick-internal.h"
  30#include "ntp_internal.h"
  31#include "timekeeping_internal.h"
  32
  33#define TK_CLEAR_NTP		(1 << 0)
  34#define TK_MIRROR		(1 << 1)
  35#define TK_CLOCK_WAS_SET	(1 << 2)
  36
  37/*
  38 * The most important data for readout fits into a single 64 byte
  39 * cache line.
  40 */
  41static struct {
  42	seqcount_t		seq;
  43	struct timekeeper	timekeeper;
  44} tk_core ____cacheline_aligned;
  45
  46static DEFINE_RAW_SPINLOCK(timekeeper_lock);
  47static struct timekeeper shadow_timekeeper;
  48
  49/**
  50 * struct tk_fast - NMI safe timekeeper
  51 * @seq:	Sequence counter for protecting updates. The lowest bit
  52 *		is the index for the tk_read_base array
  53 * @base:	tk_read_base array. Access is indexed by the lowest bit of
  54 *		@seq.
  55 *
  56 * See @update_fast_timekeeper() below.
  57 */
  58struct tk_fast {
  59	seqcount_t		seq;
  60	struct tk_read_base	base[2];
  61};
  62
  63/* Suspend-time cycles value for halted fast timekeeper. */
  64static u64 cycles_at_suspend;
  65
  66static u64 dummy_clock_read(struct clocksource *cs)
  67{
  68	return cycles_at_suspend;
  69}
  70
  71static struct clocksource dummy_clock = {
  72	.read = dummy_clock_read,
  73};
  74
  75static struct tk_fast tk_fast_mono ____cacheline_aligned = {
  76	.base[0] = { .clock = &dummy_clock, },
  77	.base[1] = { .clock = &dummy_clock, },
  78};
  79
  80static struct tk_fast tk_fast_raw  ____cacheline_aligned = {
  81	.base[0] = { .clock = &dummy_clock, },
  82	.base[1] = { .clock = &dummy_clock, },
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  83};
  84
  85/* flag for if timekeeping is suspended */
  86int __read_mostly timekeeping_suspended;
  87
  88static inline void tk_normalize_xtime(struct timekeeper *tk)
  89{
  90	while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
  91		tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
  92		tk->xtime_sec++;
  93	}
  94	while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
  95		tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
  96		tk->raw_sec++;
  97	}
  98}
  99
 100static inline struct timespec64 tk_xtime(struct timekeeper *tk)
 101{
 102	struct timespec64 ts;
 103
 104	ts.tv_sec = tk->xtime_sec;
 105	ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
 106	return ts;
 107}
 108
 109static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
 110{
 111	tk->xtime_sec = ts->tv_sec;
 112	tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
 113}
 114
 115static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
 116{
 117	tk->xtime_sec += ts->tv_sec;
 118	tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
 119	tk_normalize_xtime(tk);
 120}
 121
 122static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
 123{
 124	struct timespec64 tmp;
 125
 126	/*
 127	 * Verify consistency of: offset_real = -wall_to_monotonic
 128	 * before modifying anything
 129	 */
 130	set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
 131					-tk->wall_to_monotonic.tv_nsec);
 132	WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
 133	tk->wall_to_monotonic = wtm;
 134	set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
 135	tk->offs_real = timespec64_to_ktime(tmp);
 136	tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
 137}
 138
 139static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
 140{
 141	tk->offs_boot = ktime_add(tk->offs_boot, delta);
 142}
 143
 144/*
 145 * tk_clock_read - atomic clocksource read() helper
 146 *
 147 * This helper is necessary to use in the read paths because, while the
 148 * seqlock ensures we don't return a bad value while structures are updated,
 149 * it doesn't protect from potential crashes. There is the possibility that
 150 * the tkr's clocksource may change between the read reference, and the
 151 * clock reference passed to the read function.  This can cause crashes if
 152 * the wrong clocksource is passed to the wrong read function.
 153 * This isn't necessary to use when holding the timekeeper_lock or doing
 154 * a read of the fast-timekeeper tkrs (which is protected by its own locking
 155 * and update logic).
 156 */
 157static inline u64 tk_clock_read(struct tk_read_base *tkr)
 158{
 159	struct clocksource *clock = READ_ONCE(tkr->clock);
 160
 161	return clock->read(clock);
 162}
 163
 164#ifdef CONFIG_DEBUG_TIMEKEEPING
 165#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
 166
 167static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
 168{
 169
 170	u64 max_cycles = tk->tkr_mono.clock->max_cycles;
 171	const char *name = tk->tkr_mono.clock->name;
 172
 173	if (offset > max_cycles) {
 174		printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
 175				offset, name, max_cycles);
 176		printk_deferred("         timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
 177	} else {
 178		if (offset > (max_cycles >> 1)) {
 179			printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
 180					offset, name, max_cycles >> 1);
 181			printk_deferred("      timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
 182		}
 183	}
 184
 185	if (tk->underflow_seen) {
 186		if (jiffies - tk->last_warning > WARNING_FREQ) {
 187			printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
 188			printk_deferred("         Please report this, consider using a different clocksource, if possible.\n");
 189			printk_deferred("         Your kernel is probably still fine.\n");
 190			tk->last_warning = jiffies;
 191		}
 192		tk->underflow_seen = 0;
 193	}
 194
 195	if (tk->overflow_seen) {
 196		if (jiffies - tk->last_warning > WARNING_FREQ) {
 197			printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
 198			printk_deferred("         Please report this, consider using a different clocksource, if possible.\n");
 199			printk_deferred("         Your kernel is probably still fine.\n");
 200			tk->last_warning = jiffies;
 201		}
 202		tk->overflow_seen = 0;
 203	}
 204}
 205
 206static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
 207{
 208	struct timekeeper *tk = &tk_core.timekeeper;
 209	u64 now, last, mask, max, delta;
 210	unsigned int seq;
 211
 212	/*
 213	 * Since we're called holding a seqlock, the data may shift
 214	 * under us while we're doing the calculation. This can cause
 215	 * false positives, since we'd note a problem but throw the
 216	 * results away. So nest another seqlock here to atomically
 217	 * grab the points we are checking with.
 218	 */
 219	do {
 220		seq = read_seqcount_begin(&tk_core.seq);
 221		now = tk_clock_read(tkr);
 222		last = tkr->cycle_last;
 223		mask = tkr->mask;
 224		max = tkr->clock->max_cycles;
 225	} while (read_seqcount_retry(&tk_core.seq, seq));
 226
 227	delta = clocksource_delta(now, last, mask);
 228
 229	/*
 230	 * Try to catch underflows by checking if we are seeing small
 231	 * mask-relative negative values.
 232	 */
 233	if (unlikely((~delta & mask) < (mask >> 3))) {
 234		tk->underflow_seen = 1;
 235		delta = 0;
 236	}
 237
 238	/* Cap delta value to the max_cycles values to avoid mult overflows */
 239	if (unlikely(delta > max)) {
 240		tk->overflow_seen = 1;
 241		delta = tkr->clock->max_cycles;
 242	}
 243
 244	return delta;
 245}
 246#else
 247static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
 248{
 249}
 250static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
 251{
 252	u64 cycle_now, delta;
 253
 254	/* read clocksource */
 255	cycle_now = tk_clock_read(tkr);
 256
 257	/* calculate the delta since the last update_wall_time */
 258	delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
 259
 260	return delta;
 261}
 262#endif
 263
 264/**
 265 * tk_setup_internals - Set up internals to use clocksource clock.
 266 *
 267 * @tk:		The target timekeeper to setup.
 268 * @clock:		Pointer to clocksource.
 269 *
 270 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
 271 * pair and interval request.
 272 *
 273 * Unless you're the timekeeping code, you should not be using this!
 274 */
 275static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
 276{
 277	u64 interval;
 278	u64 tmp, ntpinterval;
 279	struct clocksource *old_clock;
 280
 281	++tk->cs_was_changed_seq;
 282	old_clock = tk->tkr_mono.clock;
 283	tk->tkr_mono.clock = clock;
 284	tk->tkr_mono.mask = clock->mask;
 285	tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
 286
 287	tk->tkr_raw.clock = clock;
 288	tk->tkr_raw.mask = clock->mask;
 289	tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
 290
 291	/* Do the ns -> cycle conversion first, using original mult */
 292	tmp = NTP_INTERVAL_LENGTH;
 293	tmp <<= clock->shift;
 294	ntpinterval = tmp;
 295	tmp += clock->mult/2;
 296	do_div(tmp, clock->mult);
 297	if (tmp == 0)
 298		tmp = 1;
 299
 300	interval = (u64) tmp;
 301	tk->cycle_interval = interval;
 302
 303	/* Go back from cycles -> shifted ns */
 304	tk->xtime_interval = interval * clock->mult;
 305	tk->xtime_remainder = ntpinterval - tk->xtime_interval;
 306	tk->raw_interval = interval * clock->mult;
 307
 308	 /* if changing clocks, convert xtime_nsec shift units */
 309	if (old_clock) {
 310		int shift_change = clock->shift - old_clock->shift;
 311		if (shift_change < 0) {
 312			tk->tkr_mono.xtime_nsec >>= -shift_change;
 313			tk->tkr_raw.xtime_nsec >>= -shift_change;
 314		} else {
 315			tk->tkr_mono.xtime_nsec <<= shift_change;
 316			tk->tkr_raw.xtime_nsec <<= shift_change;
 317		}
 318	}
 319
 320	tk->tkr_mono.shift = clock->shift;
 321	tk->tkr_raw.shift = clock->shift;
 322
 323	tk->ntp_error = 0;
 324	tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
 325	tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
 326
 327	/*
 328	 * The timekeeper keeps its own mult values for the currently
 329	 * active clocksource. These value will be adjusted via NTP
 330	 * to counteract clock drifting.
 331	 */
 332	tk->tkr_mono.mult = clock->mult;
 333	tk->tkr_raw.mult = clock->mult;
 334	tk->ntp_err_mult = 0;
 335	tk->skip_second_overflow = 0;
 336}
 337
 338/* Timekeeper helper functions. */
 339
 340#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
 341static u32 default_arch_gettimeoffset(void) { return 0; }
 342u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
 343#else
 344static inline u32 arch_gettimeoffset(void) { return 0; }
 345#endif
 346
 347static inline u64 timekeeping_delta_to_ns(struct tk_read_base *tkr, u64 delta)
 348{
 349	u64 nsec;
 350
 351	nsec = delta * tkr->mult + tkr->xtime_nsec;
 352	nsec >>= tkr->shift;
 353
 354	/* If arch requires, add in get_arch_timeoffset() */
 355	return nsec + arch_gettimeoffset();
 356}
 357
 358static inline u64 timekeeping_get_ns(struct tk_read_base *tkr)
 359{
 360	u64 delta;
 361
 362	delta = timekeeping_get_delta(tkr);
 363	return timekeeping_delta_to_ns(tkr, delta);
 364}
 365
 366static inline u64 timekeeping_cycles_to_ns(struct tk_read_base *tkr, u64 cycles)
 367{
 368	u64 delta;
 369
 370	/* calculate the delta since the last update_wall_time */
 371	delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
 372	return timekeeping_delta_to_ns(tkr, delta);
 373}
 374
 375/**
 376 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
 377 * @tkr: Timekeeping readout base from which we take the update
 378 *
 379 * We want to use this from any context including NMI and tracing /
 380 * instrumenting the timekeeping code itself.
 381 *
 382 * Employ the latch technique; see @raw_write_seqcount_latch.
 383 *
 384 * So if a NMI hits the update of base[0] then it will use base[1]
 385 * which is still consistent. In the worst case this can result is a
 386 * slightly wrong timestamp (a few nanoseconds). See
 387 * @ktime_get_mono_fast_ns.
 388 */
 389static void update_fast_timekeeper(struct tk_read_base *tkr, struct tk_fast *tkf)
 390{
 391	struct tk_read_base *base = tkf->base;
 392
 393	/* Force readers off to base[1] */
 394	raw_write_seqcount_latch(&tkf->seq);
 395
 396	/* Update base[0] */
 397	memcpy(base, tkr, sizeof(*base));
 
 398
 399	/* Force readers back to base[0] */
 400	raw_write_seqcount_latch(&tkf->seq);
 401
 402	/* Update base[1] */
 403	memcpy(base + 1, base, sizeof(*base));
 404}
 405
 406/**
 407 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
 408 *
 409 * This timestamp is not guaranteed to be monotonic across an update.
 410 * The timestamp is calculated by:
 411 *
 412 *	now = base_mono + clock_delta * slope
 413 *
 414 * So if the update lowers the slope, readers who are forced to the
 415 * not yet updated second array are still using the old steeper slope.
 416 *
 417 * tmono
 418 * ^
 419 * |    o  n
 420 * |   o n
 421 * |  u
 422 * | o
 423 * |o
 424 * |12345678---> reader order
 425 *
 426 * o = old slope
 427 * u = update
 428 * n = new slope
 429 *
 430 * So reader 6 will observe time going backwards versus reader 5.
 431 *
 432 * While other CPUs are likely to be able observe that, the only way
 433 * for a CPU local observation is when an NMI hits in the middle of
 434 * the update. Timestamps taken from that NMI context might be ahead
 435 * of the following timestamps. Callers need to be aware of that and
 436 * deal with it.
 437 */
 438static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
 439{
 440	struct tk_read_base *tkr;
 441	unsigned int seq;
 442	u64 now;
 443
 444	do {
 445		seq = raw_read_seqcount_latch(&tkf->seq);
 446		tkr = tkf->base + (seq & 0x01);
 447		now = ktime_to_ns(tkr->base);
 448
 449		now += timekeeping_delta_to_ns(tkr,
 450				clocksource_delta(
 451					tk_clock_read(tkr),
 452					tkr->cycle_last,
 453					tkr->mask));
 454	} while (read_seqcount_retry(&tkf->seq, seq));
 455
 456	return now;
 457}
 458
 459u64 ktime_get_mono_fast_ns(void)
 460{
 461	return __ktime_get_fast_ns(&tk_fast_mono);
 462}
 463EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
 464
 465u64 ktime_get_raw_fast_ns(void)
 466{
 467	return __ktime_get_fast_ns(&tk_fast_raw);
 468}
 469EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
 470
 471/**
 472 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
 473 *
 474 * To keep it NMI safe since we're accessing from tracing, we're not using a
 475 * separate timekeeper with updates to monotonic clock and boot offset
 476 * protected with seqlocks. This has the following minor side effects:
 477 *
 478 * (1) Its possible that a timestamp be taken after the boot offset is updated
 479 * but before the timekeeper is updated. If this happens, the new boot offset
 480 * is added to the old timekeeping making the clock appear to update slightly
 481 * earlier:
 482 *    CPU 0                                        CPU 1
 483 *    timekeeping_inject_sleeptime64()
 484 *    __timekeeping_inject_sleeptime(tk, delta);
 485 *                                                 timestamp();
 486 *    timekeeping_update(tk, TK_CLEAR_NTP...);
 487 *
 488 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
 489 * partially updated.  Since the tk->offs_boot update is a rare event, this
 490 * should be a rare occurrence which postprocessing should be able to handle.
 491 */
 492u64 notrace ktime_get_boot_fast_ns(void)
 493{
 494	struct timekeeper *tk = &tk_core.timekeeper;
 495
 496	return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
 
 497}
 498EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
 499
 500
 501/*
 502 * See comment for __ktime_get_fast_ns() vs. timestamp ordering
 503 */
 504static __always_inline u64 __ktime_get_real_fast_ns(struct tk_fast *tkf)
 505{
 506	struct tk_read_base *tkr;
 507	unsigned int seq;
 508	u64 now;
 509
 510	do {
 511		seq = raw_read_seqcount_latch(&tkf->seq);
 512		tkr = tkf->base + (seq & 0x01);
 513		now = ktime_to_ns(tkr->base_real);
 514
 515		now += timekeeping_delta_to_ns(tkr,
 516				clocksource_delta(
 517					tk_clock_read(tkr),
 518					tkr->cycle_last,
 519					tkr->mask));
 520	} while (read_seqcount_retry(&tkf->seq, seq));
 521
 522	return now;
 523}
 524
 525/**
 526 * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
 527 */
 528u64 ktime_get_real_fast_ns(void)
 529{
 530	return __ktime_get_real_fast_ns(&tk_fast_mono);
 531}
 532EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
 533
 534/**
 535 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
 536 * @tk: Timekeeper to snapshot.
 537 *
 538 * It generally is unsafe to access the clocksource after timekeeping has been
 539 * suspended, so take a snapshot of the readout base of @tk and use it as the
 540 * fast timekeeper's readout base while suspended.  It will return the same
 541 * number of cycles every time until timekeeping is resumed at which time the
 542 * proper readout base for the fast timekeeper will be restored automatically.
 543 */
 544static void halt_fast_timekeeper(struct timekeeper *tk)
 545{
 546	static struct tk_read_base tkr_dummy;
 547	struct tk_read_base *tkr = &tk->tkr_mono;
 548
 549	memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
 550	cycles_at_suspend = tk_clock_read(tkr);
 551	tkr_dummy.clock = &dummy_clock;
 552	tkr_dummy.base_real = tkr->base + tk->offs_real;
 553	update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
 554
 555	tkr = &tk->tkr_raw;
 556	memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
 557	tkr_dummy.clock = &dummy_clock;
 558	update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
 559}
 560
 561static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
 562
 563static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
 564{
 565	raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
 566}
 567
 568/**
 569 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
 570 */
 571int pvclock_gtod_register_notifier(struct notifier_block *nb)
 572{
 573	struct timekeeper *tk = &tk_core.timekeeper;
 574	unsigned long flags;
 575	int ret;
 576
 577	raw_spin_lock_irqsave(&timekeeper_lock, flags);
 578	ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
 579	update_pvclock_gtod(tk, true);
 580	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 581
 582	return ret;
 583}
 584EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
 585
 586/**
 587 * pvclock_gtod_unregister_notifier - unregister a pvclock
 588 * timedata update listener
 589 */
 590int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
 591{
 592	unsigned long flags;
 593	int ret;
 594
 595	raw_spin_lock_irqsave(&timekeeper_lock, flags);
 596	ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
 597	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 598
 599	return ret;
 600}
 601EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
 602
 603/*
 604 * tk_update_leap_state - helper to update the next_leap_ktime
 605 */
 606static inline void tk_update_leap_state(struct timekeeper *tk)
 607{
 608	tk->next_leap_ktime = ntp_get_next_leap();
 609	if (tk->next_leap_ktime != KTIME_MAX)
 610		/* Convert to monotonic time */
 611		tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
 612}
 
 
 
 
 
 
 
 
 613
 614/*
 615 * Update the ktime_t based scalar nsec members of the timekeeper
 616 */
 617static inline void tk_update_ktime_data(struct timekeeper *tk)
 618{
 619	u64 seconds;
 620	u32 nsec;
 621
 622	/*
 623	 * The xtime based monotonic readout is:
 624	 *	nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
 625	 * The ktime based monotonic readout is:
 626	 *	nsec = base_mono + now();
 627	 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
 628	 */
 629	seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
 630	nsec = (u32) tk->wall_to_monotonic.tv_nsec;
 631	tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
 632
 633	/*
 634	 * The sum of the nanoseconds portions of xtime and
 635	 * wall_to_monotonic can be greater/equal one second. Take
 636	 * this into account before updating tk->ktime_sec.
 637	 */
 638	nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
 639	if (nsec >= NSEC_PER_SEC)
 640		seconds++;
 641	tk->ktime_sec = seconds;
 642
 643	/* Update the monotonic raw base */
 644	tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
 645}
 646
 647/* must hold timekeeper_lock */
 648static void timekeeping_update(struct timekeeper *tk, unsigned int action)
 649{
 650	if (action & TK_CLEAR_NTP) {
 651		tk->ntp_error = 0;
 652		ntp_clear();
 653	}
 654
 655	tk_update_leap_state(tk);
 656	tk_update_ktime_data(tk);
 657
 658	update_vsyscall(tk);
 659	update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
 660
 661	tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
 662	update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
 663	update_fast_timekeeper(&tk->tkr_raw,  &tk_fast_raw);
 664
 665	if (action & TK_CLOCK_WAS_SET)
 666		tk->clock_was_set_seq++;
 667	/*
 668	 * The mirroring of the data to the shadow-timekeeper needs
 669	 * to happen last here to ensure we don't over-write the
 670	 * timekeeper structure on the next update with stale data
 671	 */
 672	if (action & TK_MIRROR)
 673		memcpy(&shadow_timekeeper, &tk_core.timekeeper,
 674		       sizeof(tk_core.timekeeper));
 675}
 676
 677/**
 678 * timekeeping_forward_now - update clock to the current time
 679 *
 680 * Forward the current clock to update its state since the last call to
 681 * update_wall_time(). This is useful before significant clock changes,
 682 * as it avoids having to deal with this time offset explicitly.
 683 */
 684static void timekeeping_forward_now(struct timekeeper *tk)
 685{
 686	u64 cycle_now, delta;
 687
 688	cycle_now = tk_clock_read(&tk->tkr_mono);
 689	delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
 690	tk->tkr_mono.cycle_last = cycle_now;
 691	tk->tkr_raw.cycle_last  = cycle_now;
 692
 693	tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
 694
 695	/* If arch requires, add in get_arch_timeoffset() */
 696	tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
 
 
 697
 
 
 698
 699	tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
 
 700
 701	/* If arch requires, add in get_arch_timeoffset() */
 702	tk->tkr_raw.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_raw.shift;
 703
 704	tk_normalize_xtime(tk);
 
 705}
 706
 707/**
 708 * __getnstimeofday64 - Returns the time of day in a timespec64.
 709 * @ts:		pointer to the timespec to be set
 710 *
 711 * Updates the time of day in the timespec.
 712 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
 713 */
 714int __getnstimeofday64(struct timespec64 *ts)
 715{
 716	struct timekeeper *tk = &tk_core.timekeeper;
 717	unsigned long seq;
 718	u64 nsecs;
 
 
 719
 720	do {
 721		seq = read_seqcount_begin(&tk_core.seq);
 722
 723		ts->tv_sec = tk->xtime_sec;
 724		nsecs = timekeeping_get_ns(&tk->tkr_mono);
 725
 726	} while (read_seqcount_retry(&tk_core.seq, seq));
 
 727
 728	ts->tv_nsec = 0;
 729	timespec64_add_ns(ts, nsecs);
 730
 731	/*
 732	 * Do not bail out early, in case there were callers still using
 733	 * the value, even in the face of the WARN_ON.
 734	 */
 735	if (unlikely(timekeeping_suspended))
 736		return -EAGAIN;
 737	return 0;
 738}
 739EXPORT_SYMBOL(__getnstimeofday64);
 740
 741/**
 742 * getnstimeofday64 - Returns the time of day in a timespec64.
 743 * @ts:		pointer to the timespec64 to be set
 744 *
 745 * Returns the time of day in a timespec64 (WARN if suspended).
 746 */
 747void getnstimeofday64(struct timespec64 *ts)
 748{
 749	WARN_ON(__getnstimeofday64(ts));
 750}
 751EXPORT_SYMBOL(getnstimeofday64);
 752
 753ktime_t ktime_get(void)
 754{
 755	struct timekeeper *tk = &tk_core.timekeeper;
 756	unsigned int seq;
 757	ktime_t base;
 758	u64 nsecs;
 759
 760	WARN_ON(timekeeping_suspended);
 761
 762	do {
 763		seq = read_seqcount_begin(&tk_core.seq);
 764		base = tk->tkr_mono.base;
 765		nsecs = timekeeping_get_ns(&tk->tkr_mono);
 
 766
 767	} while (read_seqcount_retry(&tk_core.seq, seq));
 768
 769	return ktime_add_ns(base, nsecs);
 
 
 
 770}
 771EXPORT_SYMBOL_GPL(ktime_get);
 772
 773u32 ktime_get_resolution_ns(void)
 774{
 775	struct timekeeper *tk = &tk_core.timekeeper;
 776	unsigned int seq;
 777	u32 nsecs;
 778
 779	WARN_ON(timekeeping_suspended);
 780
 781	do {
 782		seq = read_seqcount_begin(&tk_core.seq);
 783		nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
 784	} while (read_seqcount_retry(&tk_core.seq, seq));
 785
 786	return nsecs;
 787}
 788EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
 789
 790static ktime_t *offsets[TK_OFFS_MAX] = {
 791	[TK_OFFS_REAL]	= &tk_core.timekeeper.offs_real,
 792	[TK_OFFS_BOOT]	= &tk_core.timekeeper.offs_boot,
 793	[TK_OFFS_TAI]	= &tk_core.timekeeper.offs_tai,
 794};
 795
 796ktime_t ktime_get_with_offset(enum tk_offsets offs)
 797{
 798	struct timekeeper *tk = &tk_core.timekeeper;
 799	unsigned int seq;
 800	ktime_t base, *offset = offsets[offs];
 801	u64 nsecs;
 802
 803	WARN_ON(timekeeping_suspended);
 804
 805	do {
 806		seq = read_seqcount_begin(&tk_core.seq);
 807		base = ktime_add(tk->tkr_mono.base, *offset);
 808		nsecs = timekeeping_get_ns(&tk->tkr_mono);
 809
 810	} while (read_seqcount_retry(&tk_core.seq, seq));
 811
 812	return ktime_add_ns(base, nsecs);
 813
 814}
 815EXPORT_SYMBOL_GPL(ktime_get_with_offset);
 816
 817/**
 818 * ktime_mono_to_any() - convert mononotic time to any other time
 819 * @tmono:	time to convert.
 820 * @offs:	which offset to use
 821 */
 822ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
 823{
 824	ktime_t *offset = offsets[offs];
 825	unsigned long seq;
 826	ktime_t tconv;
 827
 828	do {
 829		seq = read_seqcount_begin(&tk_core.seq);
 830		tconv = ktime_add(tmono, *offset);
 831	} while (read_seqcount_retry(&tk_core.seq, seq));
 832
 833	return tconv;
 834}
 835EXPORT_SYMBOL_GPL(ktime_mono_to_any);
 836
 837/**
 838 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
 839 */
 840ktime_t ktime_get_raw(void)
 841{
 842	struct timekeeper *tk = &tk_core.timekeeper;
 843	unsigned int seq;
 844	ktime_t base;
 845	u64 nsecs;
 846
 847	do {
 848		seq = read_seqcount_begin(&tk_core.seq);
 849		base = tk->tkr_raw.base;
 850		nsecs = timekeeping_get_ns(&tk->tkr_raw);
 851
 852	} while (read_seqcount_retry(&tk_core.seq, seq));
 853
 854	return ktime_add_ns(base, nsecs);
 855}
 856EXPORT_SYMBOL_GPL(ktime_get_raw);
 857
 858/**
 859 * ktime_get_ts64 - get the monotonic clock in timespec64 format
 860 * @ts:		pointer to timespec variable
 861 *
 862 * The function calculates the monotonic clock from the realtime
 863 * clock and the wall_to_monotonic offset and stores the result
 864 * in normalized timespec64 format in the variable pointed to by @ts.
 865 */
 866void ktime_get_ts64(struct timespec64 *ts)
 867{
 868	struct timekeeper *tk = &tk_core.timekeeper;
 869	struct timespec64 tomono;
 870	unsigned int seq;
 871	u64 nsec;
 872
 873	WARN_ON(timekeeping_suspended);
 874
 875	do {
 876		seq = read_seqcount_begin(&tk_core.seq);
 877		ts->tv_sec = tk->xtime_sec;
 878		nsec = timekeeping_get_ns(&tk->tkr_mono);
 879		tomono = tk->wall_to_monotonic;
 880
 881	} while (read_seqcount_retry(&tk_core.seq, seq));
 882
 883	ts->tv_sec += tomono.tv_sec;
 884	ts->tv_nsec = 0;
 885	timespec64_add_ns(ts, nsec + tomono.tv_nsec);
 886}
 887EXPORT_SYMBOL_GPL(ktime_get_ts64);
 888
 889/**
 890 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
 891 *
 892 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
 893 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
 894 * works on both 32 and 64 bit systems. On 32 bit systems the readout
 895 * covers ~136 years of uptime which should be enough to prevent
 896 * premature wrap arounds.
 897 */
 898time64_t ktime_get_seconds(void)
 899{
 900	struct timekeeper *tk = &tk_core.timekeeper;
 901
 902	WARN_ON(timekeeping_suspended);
 903	return tk->ktime_sec;
 904}
 905EXPORT_SYMBOL_GPL(ktime_get_seconds);
 906
 907/**
 908 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
 909 *
 910 * Returns the wall clock seconds since 1970. This replaces the
 911 * get_seconds() interface which is not y2038 safe on 32bit systems.
 912 *
 913 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
 914 * 32bit systems the access must be protected with the sequence
 915 * counter to provide "atomic" access to the 64bit tk->xtime_sec
 916 * value.
 917 */
 918time64_t ktime_get_real_seconds(void)
 919{
 920	struct timekeeper *tk = &tk_core.timekeeper;
 921	time64_t seconds;
 922	unsigned int seq;
 923
 924	if (IS_ENABLED(CONFIG_64BIT))
 925		return tk->xtime_sec;
 926
 927	do {
 928		seq = read_seqcount_begin(&tk_core.seq);
 929		seconds = tk->xtime_sec;
 930
 931	} while (read_seqcount_retry(&tk_core.seq, seq));
 932
 933	return seconds;
 934}
 935EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
 936
 937/**
 938 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
 939 * but without the sequence counter protect. This internal function
 940 * is called just when timekeeping lock is already held.
 941 */
 942time64_t __ktime_get_real_seconds(void)
 943{
 944	struct timekeeper *tk = &tk_core.timekeeper;
 945
 946	return tk->xtime_sec;
 947}
 948
 949/**
 950 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
 951 * @systime_snapshot:	pointer to struct receiving the system time snapshot
 
 
 
 
 
 952 */
 953void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 954{
 955	struct timekeeper *tk = &tk_core.timekeeper;
 956	unsigned long seq;
 957	ktime_t base_raw;
 958	ktime_t base_real;
 959	u64 nsec_raw;
 960	u64 nsec_real;
 961	u64 now;
 962
 963	WARN_ON_ONCE(timekeeping_suspended);
 964
 965	do {
 966		seq = read_seqcount_begin(&tk_core.seq);
 967		now = tk_clock_read(&tk->tkr_mono);
 968		systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
 969		systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
 970		base_real = ktime_add(tk->tkr_mono.base,
 971				      tk_core.timekeeper.offs_real);
 972		base_raw = tk->tkr_raw.base;
 973		nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
 974		nsec_raw  = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
 975	} while (read_seqcount_retry(&tk_core.seq, seq));
 976
 977	systime_snapshot->cycles = now;
 978	systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
 979	systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
 980}
 981EXPORT_SYMBOL_GPL(ktime_get_snapshot);
 982
 983/* Scale base by mult/div checking for overflow */
 984static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
 985{
 986	u64 tmp, rem;
 987
 988	tmp = div64_u64_rem(*base, div, &rem);
 989
 990	if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
 991	    ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
 992		return -EOVERFLOW;
 993	tmp *= mult;
 994	rem *= mult;
 995
 996	do_div(rem, div);
 997	*base = tmp + rem;
 998	return 0;
 999}
1000
1001/**
1002 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1003 * @history:			Snapshot representing start of history
1004 * @partial_history_cycles:	Cycle offset into history (fractional part)
1005 * @total_history_cycles:	Total history length in cycles
1006 * @discontinuity:		True indicates clock was set on history period
1007 * @ts:				Cross timestamp that should be adjusted using
1008 *	partial/total ratio
1009 *
1010 * Helper function used by get_device_system_crosststamp() to correct the
1011 * crosstimestamp corresponding to the start of the current interval to the
1012 * system counter value (timestamp point) provided by the driver. The
1013 * total_history_* quantities are the total history starting at the provided
1014 * reference point and ending at the start of the current interval. The cycle
1015 * count between the driver timestamp point and the start of the current
1016 * interval is partial_history_cycles.
1017 */
1018static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1019					 u64 partial_history_cycles,
1020					 u64 total_history_cycles,
1021					 bool discontinuity,
1022					 struct system_device_crosststamp *ts)
1023{
1024	struct timekeeper *tk = &tk_core.timekeeper;
1025	u64 corr_raw, corr_real;
1026	bool interp_forward;
1027	int ret;
1028
1029	if (total_history_cycles == 0 || partial_history_cycles == 0)
1030		return 0;
1031
1032	/* Interpolate shortest distance from beginning or end of history */
1033	interp_forward = partial_history_cycles > total_history_cycles / 2;
1034	partial_history_cycles = interp_forward ?
1035		total_history_cycles - partial_history_cycles :
1036		partial_history_cycles;
1037
1038	/*
1039	 * Scale the monotonic raw time delta by:
1040	 *	partial_history_cycles / total_history_cycles
1041	 */
1042	corr_raw = (u64)ktime_to_ns(
1043		ktime_sub(ts->sys_monoraw, history->raw));
1044	ret = scale64_check_overflow(partial_history_cycles,
1045				     total_history_cycles, &corr_raw);
1046	if (ret)
1047		return ret;
1048
1049	/*
1050	 * If there is a discontinuity in the history, scale monotonic raw
1051	 *	correction by:
1052	 *	mult(real)/mult(raw) yielding the realtime correction
1053	 * Otherwise, calculate the realtime correction similar to monotonic
1054	 *	raw calculation
1055	 */
1056	if (discontinuity) {
1057		corr_real = mul_u64_u32_div
1058			(corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1059	} else {
1060		corr_real = (u64)ktime_to_ns(
1061			ktime_sub(ts->sys_realtime, history->real));
1062		ret = scale64_check_overflow(partial_history_cycles,
1063					     total_history_cycles, &corr_real);
1064		if (ret)
1065			return ret;
1066	}
1067
1068	/* Fixup monotonic raw and real time time values */
1069	if (interp_forward) {
1070		ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1071		ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1072	} else {
1073		ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1074		ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1075	}
1076
1077	return 0;
1078}
1079
1080/*
1081 * cycle_between - true if test occurs chronologically between before and after
1082 */
1083static bool cycle_between(u64 before, u64 test, u64 after)
1084{
1085	if (test > before && test < after)
1086		return true;
1087	if (test < before && before > after)
1088		return true;
1089	return false;
1090}
 
1091
1092/**
1093 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1094 * @get_time_fn:	Callback to get simultaneous device time and
1095 *	system counter from the device driver
1096 * @ctx:		Context passed to get_time_fn()
1097 * @history_begin:	Historical reference point used to interpolate system
1098 *	time when counter provided by the driver is before the current interval
1099 * @xtstamp:		Receives simultaneously captured system and device time
1100 *
1101 * Reads a timestamp from a device and correlates it to system time
1102 */
1103int get_device_system_crosststamp(int (*get_time_fn)
1104				  (ktime_t *device_time,
1105				   struct system_counterval_t *sys_counterval,
1106				   void *ctx),
1107				  void *ctx,
1108				  struct system_time_snapshot *history_begin,
1109				  struct system_device_crosststamp *xtstamp)
1110{
1111	struct system_counterval_t system_counterval;
1112	struct timekeeper *tk = &tk_core.timekeeper;
1113	u64 cycles, now, interval_start;
1114	unsigned int clock_was_set_seq = 0;
1115	ktime_t base_real, base_raw;
1116	u64 nsec_real, nsec_raw;
1117	u8 cs_was_changed_seq;
1118	unsigned long seq;
1119	bool do_interp;
1120	int ret;
1121
1122	do {
1123		seq = read_seqcount_begin(&tk_core.seq);
1124		/*
1125		 * Try to synchronously capture device time and a system
1126		 * counter value calling back into the device driver
1127		 */
1128		ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1129		if (ret)
1130			return ret;
1131
1132		/*
1133		 * Verify that the clocksource associated with the captured
1134		 * system counter value is the same as the currently installed
1135		 * timekeeper clocksource
1136		 */
1137		if (tk->tkr_mono.clock != system_counterval.cs)
1138			return -ENODEV;
1139		cycles = system_counterval.cycles;
1140
1141		/*
1142		 * Check whether the system counter value provided by the
1143		 * device driver is on the current timekeeping interval.
1144		 */
1145		now = tk_clock_read(&tk->tkr_mono);
1146		interval_start = tk->tkr_mono.cycle_last;
1147		if (!cycle_between(interval_start, cycles, now)) {
1148			clock_was_set_seq = tk->clock_was_set_seq;
1149			cs_was_changed_seq = tk->cs_was_changed_seq;
1150			cycles = interval_start;
1151			do_interp = true;
1152		} else {
1153			do_interp = false;
1154		}
1155
1156		base_real = ktime_add(tk->tkr_mono.base,
1157				      tk_core.timekeeper.offs_real);
1158		base_raw = tk->tkr_raw.base;
1159
1160		nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1161						     system_counterval.cycles);
1162		nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1163						    system_counterval.cycles);
1164	} while (read_seqcount_retry(&tk_core.seq, seq));
1165
1166	xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1167	xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1168
1169	/*
1170	 * Interpolate if necessary, adjusting back from the start of the
1171	 * current interval
1172	 */
1173	if (do_interp) {
1174		u64 partial_history_cycles, total_history_cycles;
1175		bool discontinuity;
1176
1177		/*
1178		 * Check that the counter value occurs after the provided
1179		 * history reference and that the history doesn't cross a
1180		 * clocksource change
1181		 */
1182		if (!history_begin ||
1183		    !cycle_between(history_begin->cycles,
1184				   system_counterval.cycles, cycles) ||
1185		    history_begin->cs_was_changed_seq != cs_was_changed_seq)
1186			return -EINVAL;
1187		partial_history_cycles = cycles - system_counterval.cycles;
1188		total_history_cycles = cycles - history_begin->cycles;
1189		discontinuity =
1190			history_begin->clock_was_set_seq != clock_was_set_seq;
1191
1192		ret = adjust_historical_crosststamp(history_begin,
1193						    partial_history_cycles,
1194						    total_history_cycles,
1195						    discontinuity, xtstamp);
1196		if (ret)
1197			return ret;
1198	}
1199
1200	return 0;
1201}
1202EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1203
1204/**
1205 * do_gettimeofday - Returns the time of day in a timeval
1206 * @tv:		pointer to the timeval to be set
1207 *
1208 * NOTE: Users should be converted to using getnstimeofday()
1209 */
1210void do_gettimeofday(struct timeval *tv)
1211{
1212	struct timespec64 now;
1213
1214	getnstimeofday64(&now);
1215	tv->tv_sec = now.tv_sec;
1216	tv->tv_usec = now.tv_nsec/1000;
1217}
1218EXPORT_SYMBOL(do_gettimeofday);
1219
 
1220/**
1221 * do_settimeofday64 - Sets the time of day.
1222 * @ts:     pointer to the timespec64 variable containing the new time
1223 *
1224 * Sets the time of day to the new time and update NTP and notify hrtimers
1225 */
1226int do_settimeofday64(const struct timespec64 *ts)
1227{
1228	struct timekeeper *tk = &tk_core.timekeeper;
1229	struct timespec64 ts_delta, xt;
1230	unsigned long flags;
1231	int ret = 0;
1232
1233	if (!timespec64_valid_strict(ts))
1234		return -EINVAL;
1235
1236	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1237	write_seqcount_begin(&tk_core.seq);
1238
1239	timekeeping_forward_now(tk);
1240
1241	xt = tk_xtime(tk);
1242	ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1243	ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1244
1245	if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1246		ret = -EINVAL;
1247		goto out;
1248	}
1249
1250	tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
 
1251
1252	tk_set_xtime(tk, ts);
1253out:
1254	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1255
1256	write_seqcount_end(&tk_core.seq);
1257	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1258
1259	/* signal hrtimers about time change */
1260	clock_was_set();
1261
1262	return ret;
1263}
1264EXPORT_SYMBOL(do_settimeofday64);
 
 
1265
1266/**
1267 * timekeeping_inject_offset - Adds or subtracts from the current time.
1268 * @tv:		pointer to the timespec variable containing the offset
1269 *
1270 * Adds or subtracts an offset value from the current time.
1271 */
1272static int timekeeping_inject_offset(struct timespec64 *ts)
1273{
1274	struct timekeeper *tk = &tk_core.timekeeper;
1275	unsigned long flags;
1276	struct timespec64 tmp;
1277	int ret = 0;
1278
1279	if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1280		return -EINVAL;
1281
1282	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1283	write_seqcount_begin(&tk_core.seq);
1284
1285	timekeeping_forward_now(tk);
1286
1287	/* Make sure the proposed value is valid */
1288	tmp = timespec64_add(tk_xtime(tk), *ts);
1289	if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1290	    !timespec64_valid_strict(&tmp)) {
1291		ret = -EINVAL;
1292		goto error;
1293	}
1294
1295	tk_xtime_add(tk, ts);
1296	tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1297
1298error: /* even if we error out, we forwarded the time, so call update */
1299	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1300
1301	write_seqcount_end(&tk_core.seq);
1302	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1303
1304	/* signal hrtimers about time change */
1305	clock_was_set();
1306
1307	return ret;
1308}
1309
1310/*
1311 * Indicates if there is an offset between the system clock and the hardware
1312 * clock/persistent clock/rtc.
1313 */
1314int persistent_clock_is_local;
1315
1316/*
1317 * Adjust the time obtained from the CMOS to be UTC time instead of
1318 * local time.
1319 *
1320 * This is ugly, but preferable to the alternatives.  Otherwise we
1321 * would either need to write a program to do it in /etc/rc (and risk
1322 * confusion if the program gets run more than once; it would also be
1323 * hard to make the program warp the clock precisely n hours)  or
1324 * compile in the timezone information into the kernel.  Bad, bad....
1325 *
1326 *						- TYT, 1992-01-01
1327 *
1328 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1329 * as real UNIX machines always do it. This avoids all headaches about
1330 * daylight saving times and warping kernel clocks.
1331 */
1332void timekeeping_warp_clock(void)
1333{
1334	if (sys_tz.tz_minuteswest != 0) {
1335		struct timespec64 adjust;
1336
1337		persistent_clock_is_local = 1;
1338		adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1339		adjust.tv_nsec = 0;
1340		timekeeping_inject_offset(&adjust);
1341	}
1342}
1343
1344/**
1345 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1346 *
1347 */
1348static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1349{
1350	tk->tai_offset = tai_offset;
1351	tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1352}
 
1353
1354/**
1355 * change_clocksource - Swaps clocksources if a new one is available
1356 *
1357 * Accumulates current time interval and initializes new clocksource
1358 */
1359static int change_clocksource(void *data)
1360{
1361	struct timekeeper *tk = &tk_core.timekeeper;
1362	struct clocksource *new, *old;
1363	unsigned long flags;
1364
1365	new = (struct clocksource *) data;
1366
1367	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1368	write_seqcount_begin(&tk_core.seq);
1369
1370	timekeeping_forward_now(tk);
1371	/*
1372	 * If the cs is in module, get a module reference. Succeeds
1373	 * for built-in code (owner == NULL) as well.
1374	 */
1375	if (try_module_get(new->owner)) {
1376		if (!new->enable || new->enable(new) == 0) {
1377			old = tk->tkr_mono.clock;
1378			tk_setup_internals(tk, new);
1379			if (old->disable)
1380				old->disable(old);
1381			module_put(old->owner);
1382		} else {
1383			module_put(new->owner);
1384		}
1385	}
1386	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1387
1388	write_seqcount_end(&tk_core.seq);
1389	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1390
1391	return 0;
1392}
1393
1394/**
1395 * timekeeping_notify - Install a new clock source
1396 * @clock:		pointer to the clock source
1397 *
1398 * This function is called from clocksource.c after a new, better clock
1399 * source has been registered. The caller holds the clocksource_mutex.
1400 */
1401int timekeeping_notify(struct clocksource *clock)
1402{
1403	struct timekeeper *tk = &tk_core.timekeeper;
1404
1405	if (tk->tkr_mono.clock == clock)
1406		return 0;
1407	stop_machine(change_clocksource, clock, NULL);
1408	tick_clock_notify();
1409	return tk->tkr_mono.clock == clock ? 0 : -1;
1410}
1411
1412/**
1413 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
1414 * @ts:		pointer to the timespec64 to be set
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1415 *
1416 * Returns the raw monotonic time (completely un-modified by ntp)
1417 */
1418void getrawmonotonic64(struct timespec64 *ts)
1419{
1420	struct timekeeper *tk = &tk_core.timekeeper;
1421	unsigned long seq;
1422	u64 nsecs;
1423
1424	do {
1425		seq = read_seqcount_begin(&tk_core.seq);
1426		ts->tv_sec = tk->raw_sec;
1427		nsecs = timekeeping_get_ns(&tk->tkr_raw);
1428
1429	} while (read_seqcount_retry(&tk_core.seq, seq));
1430
1431	ts->tv_nsec = 0;
1432	timespec64_add_ns(ts, nsecs);
1433}
1434EXPORT_SYMBOL(getrawmonotonic64);
1435
1436
1437/**
1438 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1439 */
1440int timekeeping_valid_for_hres(void)
1441{
1442	struct timekeeper *tk = &tk_core.timekeeper;
1443	unsigned long seq;
1444	int ret;
1445
1446	do {
1447		seq = read_seqcount_begin(&tk_core.seq);
1448
1449		ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1450
1451	} while (read_seqcount_retry(&tk_core.seq, seq));
1452
1453	return ret;
1454}
1455
1456/**
1457 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
 
 
 
1458 */
1459u64 timekeeping_max_deferment(void)
1460{
1461	struct timekeeper *tk = &tk_core.timekeeper;
1462	unsigned long seq;
1463	u64 ret;
1464
1465	do {
1466		seq = read_seqcount_begin(&tk_core.seq);
1467
1468		ret = tk->tkr_mono.clock->max_idle_ns;
1469
1470	} while (read_seqcount_retry(&tk_core.seq, seq));
1471
1472	return ret;
1473}
1474
1475/**
1476 * read_persistent_clock -  Return time from the persistent clock.
1477 *
1478 * Weak dummy function for arches that do not yet support it.
1479 * Reads the time from the battery backed persistent clock.
1480 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1481 *
1482 *  XXX - Do be sure to remove it once all arches implement it.
1483 */
1484void __weak read_persistent_clock(struct timespec *ts)
1485{
1486	ts->tv_sec = 0;
1487	ts->tv_nsec = 0;
1488}
1489
1490void __weak read_persistent_clock64(struct timespec64 *ts64)
1491{
1492	struct timespec ts;
1493
1494	read_persistent_clock(&ts);
1495	*ts64 = timespec_to_timespec64(ts);
1496}
1497
1498/**
1499 * read_boot_clock64 -  Return time of the system start.
1500 *
1501 * Weak dummy function for arches that do not yet support it.
1502 * Function to read the exact time the system has been started.
1503 * Returns a timespec64 with tv_sec=0 and tv_nsec=0 if unsupported.
1504 *
1505 *  XXX - Do be sure to remove it once all arches implement it.
1506 */
1507void __weak read_boot_clock64(struct timespec64 *ts)
1508{
1509	ts->tv_sec = 0;
1510	ts->tv_nsec = 0;
1511}
1512
1513/* Flag for if timekeeping_resume() has injected sleeptime */
1514static bool sleeptime_injected;
1515
1516/* Flag for if there is a persistent clock on this platform */
1517static bool persistent_clock_exists;
1518
1519/*
1520 * timekeeping_init - Initializes the clocksource and common timekeeping values
1521 */
1522void __init timekeeping_init(void)
1523{
1524	struct timekeeper *tk = &tk_core.timekeeper;
1525	struct clocksource *clock;
1526	unsigned long flags;
1527	struct timespec64 now, boot, tmp;
1528
1529	read_persistent_clock64(&now);
1530	if (!timespec64_valid_strict(&now)) {
1531		pr_warn("WARNING: Persistent clock returned invalid value!\n"
1532			"         Check your CMOS/BIOS settings.\n");
1533		now.tv_sec = 0;
1534		now.tv_nsec = 0;
1535	} else if (now.tv_sec || now.tv_nsec)
1536		persistent_clock_exists = true;
1537
1538	read_boot_clock64(&boot);
1539	if (!timespec64_valid_strict(&boot)) {
1540		pr_warn("WARNING: Boot clock returned invalid value!\n"
1541			"         Check your CMOS/BIOS settings.\n");
1542		boot.tv_sec = 0;
1543		boot.tv_nsec = 0;
1544	}
1545
1546	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1547	write_seqcount_begin(&tk_core.seq);
1548	ntp_init();
1549
1550	clock = clocksource_default_clock();
1551	if (clock->enable)
1552		clock->enable(clock);
1553	tk_setup_internals(tk, clock);
1554
1555	tk_set_xtime(tk, &now);
1556	tk->raw_sec = 0;
1557	if (boot.tv_sec == 0 && boot.tv_nsec == 0)
1558		boot = tk_xtime(tk);
1559
1560	set_normalized_timespec64(&tmp, -boot.tv_sec, -boot.tv_nsec);
1561	tk_set_wall_to_mono(tk, tmp);
1562
1563	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1564
1565	write_seqcount_end(&tk_core.seq);
1566	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 
 
 
 
 
 
1567}
1568
1569/* time in seconds when suspend began for persistent clock */
1570static struct timespec64 timekeeping_suspend_time;
1571
1572/**
1573 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1574 * @delta: pointer to a timespec delta value
1575 *
1576 * Takes a timespec offset measuring a suspend interval and properly
1577 * adds the sleep offset to the timekeeping variables.
1578 */
1579static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1580					   struct timespec64 *delta)
1581{
1582	if (!timespec64_valid_strict(delta)) {
1583		printk_deferred(KERN_WARNING
1584				"__timekeeping_inject_sleeptime: Invalid "
1585				"sleep delta value!\n");
1586		return;
1587	}
1588	tk_xtime_add(tk, delta);
1589	tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1590	tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1591	tk_debug_account_sleep_time(delta);
1592}
1593
1594#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1595/**
1596 * We have three kinds of time sources to use for sleep time
1597 * injection, the preference order is:
1598 * 1) non-stop clocksource
1599 * 2) persistent clock (ie: RTC accessible when irqs are off)
1600 * 3) RTC
1601 *
1602 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1603 * If system has neither 1) nor 2), 3) will be used finally.
1604 *
1605 *
1606 * If timekeeping has injected sleeptime via either 1) or 2),
1607 * 3) becomes needless, so in this case we don't need to call
1608 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1609 * means.
1610 */
1611bool timekeeping_rtc_skipresume(void)
1612{
1613	return sleeptime_injected;
1614}
1615
1616/**
1617 * 1) can be determined whether to use or not only when doing
1618 * timekeeping_resume() which is invoked after rtc_suspend(),
1619 * so we can't skip rtc_suspend() surely if system has 1).
1620 *
1621 * But if system has 2), 2) will definitely be used, so in this
1622 * case we don't need to call rtc_suspend(), and this is what
1623 * timekeeping_rtc_skipsuspend() means.
1624 */
1625bool timekeeping_rtc_skipsuspend(void)
1626{
1627	return persistent_clock_exists;
1628}
1629
1630/**
1631 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1632 * @delta: pointer to a timespec64 delta value
1633 *
1634 * This hook is for architectures that cannot support read_persistent_clock64
1635 * because their RTC/persistent clock is only accessible when irqs are enabled.
1636 * and also don't have an effective nonstop clocksource.
1637 *
1638 * This function should only be called by rtc_resume(), and allows
1639 * a suspend offset to be injected into the timekeeping values.
1640 */
1641void timekeeping_inject_sleeptime64(struct timespec64 *delta)
1642{
1643	struct timekeeper *tk = &tk_core.timekeeper;
1644	unsigned long flags;
 
1645
1646	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1647	write_seqcount_begin(&tk_core.seq);
 
 
1648
1649	timekeeping_forward_now(tk);
 
1650
1651	__timekeeping_inject_sleeptime(tk, delta);
1652
1653	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
 
 
 
1654
1655	write_seqcount_end(&tk_core.seq);
1656	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1657
1658	/* signal hrtimers about time change */
1659	clock_was_set();
1660}
1661#endif
1662
1663/**
1664 * timekeeping_resume - Resumes the generic timekeeping subsystem.
 
 
 
 
1665 */
1666void timekeeping_resume(void)
1667{
1668	struct timekeeper *tk = &tk_core.timekeeper;
1669	struct clocksource *clock = tk->tkr_mono.clock;
1670	unsigned long flags;
1671	struct timespec64 ts_new, ts_delta;
1672	u64 cycle_now;
1673
1674	sleeptime_injected = false;
1675	read_persistent_clock64(&ts_new);
1676
1677	clockevents_resume();
1678	clocksource_resume();
1679
1680	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1681	write_seqcount_begin(&tk_core.seq);
1682
1683	/*
1684	 * After system resumes, we need to calculate the suspended time and
1685	 * compensate it for the OS time. There are 3 sources that could be
1686	 * used: Nonstop clocksource during suspend, persistent clock and rtc
1687	 * device.
1688	 *
1689	 * One specific platform may have 1 or 2 or all of them, and the
1690	 * preference will be:
1691	 *	suspend-nonstop clocksource -> persistent clock -> rtc
1692	 * The less preferred source will only be tried if there is no better
1693	 * usable source. The rtc part is handled separately in rtc core code.
1694	 */
1695	cycle_now = tk_clock_read(&tk->tkr_mono);
1696	if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
1697		cycle_now > tk->tkr_mono.cycle_last) {
1698		u64 nsec, cyc_delta;
1699
1700		cyc_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last,
1701					      tk->tkr_mono.mask);
1702		nsec = mul_u64_u32_shr(cyc_delta, clock->mult, clock->shift);
1703		ts_delta = ns_to_timespec64(nsec);
1704		sleeptime_injected = true;
1705	} else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1706		ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1707		sleeptime_injected = true;
1708	}
1709
1710	if (sleeptime_injected)
1711		__timekeeping_inject_sleeptime(tk, &ts_delta);
1712
1713	/* Re-base the last cycle value */
1714	tk->tkr_mono.cycle_last = cycle_now;
1715	tk->tkr_raw.cycle_last  = cycle_now;
1716
1717	tk->ntp_error = 0;
1718	timekeeping_suspended = 0;
1719	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1720	write_seqcount_end(&tk_core.seq);
1721	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1722
1723	touch_softlockup_watchdog();
1724
1725	tick_resume();
 
 
1726	hrtimers_resume();
1727}
1728
1729int timekeeping_suspend(void)
1730{
1731	struct timekeeper *tk = &tk_core.timekeeper;
1732	unsigned long flags;
1733	struct timespec64		delta, delta_delta;
1734	static struct timespec64	old_delta;
1735
1736	read_persistent_clock64(&timekeeping_suspend_time);
1737
1738	/*
1739	 * On some systems the persistent_clock can not be detected at
1740	 * timekeeping_init by its return value, so if we see a valid
1741	 * value returned, update the persistent_clock_exists flag.
1742	 */
1743	if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1744		persistent_clock_exists = true;
1745
1746	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1747	write_seqcount_begin(&tk_core.seq);
1748	timekeeping_forward_now(tk);
1749	timekeeping_suspended = 1;
1750
1751	if (persistent_clock_exists) {
 
 
 
 
 
 
 
 
1752		/*
1753		 * To avoid drift caused by repeated suspend/resumes,
1754		 * which each can add ~1 second drift error,
1755		 * try to compensate so the difference in system time
1756		 * and persistent_clock time stays close to constant.
1757		 */
1758		delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1759		delta_delta = timespec64_sub(delta, old_delta);
1760		if (abs(delta_delta.tv_sec) >= 2) {
1761			/*
1762			 * if delta_delta is too large, assume time correction
1763			 * has occurred and set old_delta to the current delta.
1764			 */
1765			old_delta = delta;
1766		} else {
1767			/* Otherwise try to adjust old_system to compensate */
1768			timekeeping_suspend_time =
1769				timespec64_add(timekeeping_suspend_time, delta_delta);
1770		}
1771	}
 
1772
1773	timekeeping_update(tk, TK_MIRROR);
1774	halt_fast_timekeeper(tk);
1775	write_seqcount_end(&tk_core.seq);
1776	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1777
1778	tick_suspend();
1779	clocksource_suspend();
1780	clockevents_suspend();
1781
1782	return 0;
1783}
1784
1785/* sysfs resume/suspend bits for timekeeping */
1786static struct syscore_ops timekeeping_syscore_ops = {
1787	.resume		= timekeeping_resume,
1788	.suspend	= timekeeping_suspend,
1789};
1790
1791static int __init timekeeping_init_ops(void)
1792{
1793	register_syscore_ops(&timekeeping_syscore_ops);
1794	return 0;
1795}
 
1796device_initcall(timekeeping_init_ops);
1797
1798/*
1799 * Apply a multiplier adjustment to the timekeeper
 
1800 */
1801static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1802							 s64 offset,
1803							 s32 mult_adj)
1804{
1805	s64 interval = tk->cycle_interval;
1806
1807	if (mult_adj == 0) {
1808		return;
1809	} else if (mult_adj == -1) {
1810		interval = -interval;
1811		offset = -offset;
1812	} else if (mult_adj != 1) {
1813		interval *= mult_adj;
1814		offset *= mult_adj;
1815	}
1816
1817	/*
1818	 * So the following can be confusing.
1819	 *
1820	 * To keep things simple, lets assume mult_adj == 1 for now.
1821	 *
1822	 * When mult_adj != 1, remember that the interval and offset values
1823	 * have been appropriately scaled so the math is the same.
1824	 *
1825	 * The basic idea here is that we're increasing the multiplier
1826	 * by one, this causes the xtime_interval to be incremented by
1827	 * one cycle_interval. This is because:
1828	 *	xtime_interval = cycle_interval * mult
1829	 * So if mult is being incremented by one:
1830	 *	xtime_interval = cycle_interval * (mult + 1)
1831	 * Its the same as:
1832	 *	xtime_interval = (cycle_interval * mult) + cycle_interval
1833	 * Which can be shortened to:
1834	 *	xtime_interval += cycle_interval
1835	 *
1836	 * So offset stores the non-accumulated cycles. Thus the current
1837	 * time (in shifted nanoseconds) is:
1838	 *	now = (offset * adj) + xtime_nsec
1839	 * Now, even though we're adjusting the clock frequency, we have
1840	 * to keep time consistent. In other words, we can't jump back
1841	 * in time, and we also want to avoid jumping forward in time.
1842	 *
1843	 * So given the same offset value, we need the time to be the same
1844	 * both before and after the freq adjustment.
1845	 *	now = (offset * adj_1) + xtime_nsec_1
1846	 *	now = (offset * adj_2) + xtime_nsec_2
1847	 * So:
1848	 *	(offset * adj_1) + xtime_nsec_1 =
1849	 *		(offset * adj_2) + xtime_nsec_2
1850	 * And we know:
1851	 *	adj_2 = adj_1 + 1
1852	 * So:
1853	 *	(offset * adj_1) + xtime_nsec_1 =
1854	 *		(offset * (adj_1+1)) + xtime_nsec_2
1855	 *	(offset * adj_1) + xtime_nsec_1 =
1856	 *		(offset * adj_1) + offset + xtime_nsec_2
1857	 * Canceling the sides:
1858	 *	xtime_nsec_1 = offset + xtime_nsec_2
1859	 * Which gives us:
1860	 *	xtime_nsec_2 = xtime_nsec_1 - offset
1861	 * Which simplfies to:
1862	 *	xtime_nsec -= offset
1863	 */
1864	if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1865		/* NTP adjustment caused clocksource mult overflow */
1866		WARN_ON_ONCE(1);
1867		return;
1868	}
1869
1870	tk->tkr_mono.mult += mult_adj;
1871	tk->xtime_interval += interval;
1872	tk->tkr_mono.xtime_nsec -= offset;
1873}
1874
1875/*
1876 * Adjust the timekeeper's multiplier to the correct frequency
1877 * and also to reduce the accumulated error value.
1878 */
1879static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1880{
1881	u32 mult;
1882
1883	/*
1884	 * Determine the multiplier from the current NTP tick length.
1885	 * Avoid expensive division when the tick length doesn't change.
1886	 */
1887	if (likely(tk->ntp_tick == ntp_tick_length())) {
1888		mult = tk->tkr_mono.mult - tk->ntp_err_mult;
1889	} else {
1890		tk->ntp_tick = ntp_tick_length();
1891		mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
1892				 tk->xtime_remainder, tk->cycle_interval);
1893	}
1894
1895	/*
1896	 * If the clock is behind the NTP time, increase the multiplier by 1
1897	 * to catch up with it. If it's ahead and there was a remainder in the
1898	 * tick division, the clock will slow down. Otherwise it will stay
1899	 * ahead until the tick length changes to a non-divisible value.
1900	 */
1901	tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
1902	mult += tk->ntp_err_mult;
1903
1904	timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
1905
1906	if (unlikely(tk->tkr_mono.clock->maxadj &&
1907		(abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
1908			> tk->tkr_mono.clock->maxadj))) {
1909		printk_once(KERN_WARNING
1910			"Adjusting %s more than 11%% (%ld vs %ld)\n",
1911			tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
1912			(long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
1913	}
1914
1915	/*
1916	 * It may be possible that when we entered this function, xtime_nsec
1917	 * was very small.  Further, if we're slightly speeding the clocksource
1918	 * in the code above, its possible the required corrective factor to
1919	 * xtime_nsec could cause it to underflow.
1920	 *
1921	 * Now, since we have already accumulated the second and the NTP
1922	 * subsystem has been notified via second_overflow(), we need to skip
1923	 * the next update.
1924	 */
1925	if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
1926		tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
1927							tk->tkr_mono.shift;
1928		tk->xtime_sec--;
1929		tk->skip_second_overflow = 1;
1930	}
1931}
1932
1933/**
1934 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1935 *
1936 * Helper function that accumulates the nsecs greater than a second
1937 * from the xtime_nsec field to the xtime_secs field.
1938 * It also calls into the NTP code to handle leapsecond processing.
1939 *
1940 */
1941static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1942{
1943	u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
1944	unsigned int clock_set = 0;
1945
1946	while (tk->tkr_mono.xtime_nsec >= nsecps) {
1947		int leap;
1948
1949		tk->tkr_mono.xtime_nsec -= nsecps;
1950		tk->xtime_sec++;
1951
1952		/*
1953		 * Skip NTP update if this second was accumulated before,
1954		 * i.e. xtime_nsec underflowed in timekeeping_adjust()
1955		 */
1956		if (unlikely(tk->skip_second_overflow)) {
1957			tk->skip_second_overflow = 0;
1958			continue;
1959		}
1960
1961		/* Figure out if its a leap sec and apply if needed */
1962		leap = second_overflow(tk->xtime_sec);
1963		if (unlikely(leap)) {
1964			struct timespec64 ts;
1965
1966			tk->xtime_sec += leap;
1967
1968			ts.tv_sec = leap;
1969			ts.tv_nsec = 0;
1970			tk_set_wall_to_mono(tk,
1971				timespec64_sub(tk->wall_to_monotonic, ts));
1972
1973			__timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1974
1975			clock_set = TK_CLOCK_WAS_SET;
1976		}
1977	}
1978	return clock_set;
1979}
1980
1981/**
1982 * logarithmic_accumulation - shifted accumulation of cycles
1983 *
1984 * This functions accumulates a shifted interval of cycles into
1985 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1986 * loop.
1987 *
1988 * Returns the unconsumed cycles.
1989 */
1990static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
1991				    u32 shift, unsigned int *clock_set)
1992{
1993	u64 interval = tk->cycle_interval << shift;
1994	u64 snsec_per_sec;
1995
1996	/* If the offset is smaller than a shifted interval, do nothing */
1997	if (offset < interval)
1998		return offset;
1999
2000	/* Accumulate one shifted interval */
2001	offset -= interval;
2002	tk->tkr_mono.cycle_last += interval;
2003	tk->tkr_raw.cycle_last  += interval;
2004
2005	tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2006	*clock_set |= accumulate_nsecs_to_secs(tk);
 
 
 
 
2007
2008	/* Accumulate raw time */
2009	tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2010	snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2011	while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2012		tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2013		tk->raw_sec++;
 
2014	}
 
2015
2016	/* Accumulate error between NTP and clock interval */
2017	tk->ntp_error += tk->ntp_tick << shift;
2018	tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2019						(tk->ntp_error_shift + shift);
 
2020
2021	return offset;
2022}
2023
 
2024/**
2025 * update_wall_time - Uses the current clocksource to increment the wall time
2026 *
 
2027 */
2028void update_wall_time(void)
2029{
2030	struct timekeeper *real_tk = &tk_core.timekeeper;
2031	struct timekeeper *tk = &shadow_timekeeper;
2032	u64 offset;
2033	int shift = 0, maxshift;
2034	unsigned int clock_set = 0;
2035	unsigned long flags;
2036
2037	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2038
2039	/* Make sure we're fully resumed: */
2040	if (unlikely(timekeeping_suspended))
2041		goto out;
 
 
2042
2043#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
2044	offset = real_tk->cycle_interval;
2045#else
2046	offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2047				   tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2048#endif
2049
2050	/* Check if there's really nothing to do */
2051	if (offset < real_tk->cycle_interval)
2052		goto out;
2053
2054	/* Do some additional sanity checking */
2055	timekeeping_check_update(tk, offset);
2056
2057	/*
2058	 * With NO_HZ we may have to accumulate many cycle_intervals
2059	 * (think "ticks") worth of time at once. To do this efficiently,
2060	 * we calculate the largest doubling multiple of cycle_intervals
2061	 * that is smaller than the offset.  We then accumulate that
2062	 * chunk in one go, and then try to consume the next smaller
2063	 * doubled multiple.
2064	 */
2065	shift = ilog2(offset) - ilog2(tk->cycle_interval);
2066	shift = max(0, shift);
2067	/* Bound shift to one less than what overflows tick_length */
2068	maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2069	shift = min(shift, maxshift);
2070	while (offset >= tk->cycle_interval) {
2071		offset = logarithmic_accumulation(tk, offset, shift,
2072							&clock_set);
2073		if (offset < tk->cycle_interval<<shift)
2074			shift--;
2075	}
2076
2077	/* Adjust the multiplier to correct NTP error */
2078	timekeeping_adjust(tk, offset);
2079
2080	/*
2081	 * Finally, make sure that after the rounding
2082	 * xtime_nsec isn't larger than NSEC_PER_SEC
 
 
 
 
 
 
 
 
 
 
 
 
2083	 */
2084	clock_set |= accumulate_nsecs_to_secs(tk);
 
 
 
 
 
2085
2086	write_seqcount_begin(&tk_core.seq);
2087	/*
2088	 * Update the real timekeeper.
2089	 *
2090	 * We could avoid this memcpy by switching pointers, but that
2091	 * requires changes to all other timekeeper usage sites as
2092	 * well, i.e. move the timekeeper pointer getter into the
2093	 * spinlocked/seqcount protected sections. And we trade this
2094	 * memcpy under the tk_core.seq against one before we start
2095	 * updating.
 
 
 
2096	 */
2097	timekeeping_update(tk, clock_set);
2098	memcpy(real_tk, tk, sizeof(*tk));
2099	/* The memcpy must come last. Do not put anything here! */
2100	write_seqcount_end(&tk_core.seq);
2101out:
2102	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2103	if (clock_set)
2104		/* Have to call _delayed version, since in irq context*/
2105		clock_was_set_delayed();
2106}
2107
2108/**
2109 * getboottime64 - Return the real time of system boot.
2110 * @ts:		pointer to the timespec64 to be set
2111 *
2112 * Returns the wall-time of boot in a timespec64.
2113 *
2114 * This is based on the wall_to_monotonic offset and the total suspend
2115 * time. Calls to settimeofday will affect the value returned (which
2116 * basically means that however wrong your real time clock is at boot time,
2117 * you get the right time here).
2118 */
2119void getboottime64(struct timespec64 *ts)
2120{
2121	struct timekeeper *tk = &tk_core.timekeeper;
2122	ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
 
 
2123
2124	*ts = ktime_to_timespec64(t);
2125}
2126EXPORT_SYMBOL_GPL(getboottime64);
2127
2128unsigned long get_seconds(void)
 
 
 
 
 
 
 
 
 
 
2129{
2130	struct timekeeper *tk = &tk_core.timekeeper;
 
 
 
 
2131
2132	return tk->xtime_sec;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2133}
2134EXPORT_SYMBOL(get_seconds);
2135
2136struct timespec64 current_kernel_time64(void)
 
 
 
 
 
2137{
2138	struct timekeeper *tk = &tk_core.timekeeper;
2139	struct timespec64 now;
2140	unsigned long seq;
2141
2142	do {
2143		seq = read_seqcount_begin(&tk_core.seq);
2144
2145		now = tk_xtime(tk);
2146	} while (read_seqcount_retry(&tk_core.seq, seq));
2147
2148	return now;
2149}
2150EXPORT_SYMBOL(current_kernel_time64);
2151
2152struct timespec64 get_monotonic_coarse64(void)
2153{
2154	struct timekeeper *tk = &tk_core.timekeeper;
2155	struct timespec64 now, mono;
2156	unsigned long seq;
2157
2158	do {
2159		seq = read_seqcount_begin(&tk_core.seq);
2160
2161		now = tk_xtime(tk);
2162		mono = tk->wall_to_monotonic;
2163	} while (read_seqcount_retry(&tk_core.seq, seq));
2164
2165	set_normalized_timespec64(&now, now.tv_sec + mono.tv_sec,
2166				now.tv_nsec + mono.tv_nsec);
2167
2168	return now;
2169}
2170EXPORT_SYMBOL(get_monotonic_coarse64);
2171
2172/*
2173 * Must hold jiffies_lock
 
 
2174 */
2175void do_timer(unsigned long ticks)
2176{
2177	jiffies_64 += ticks;
 
2178	calc_global_load(ticks);
2179}
2180
2181/**
2182 * ktime_get_update_offsets_now - hrtimer helper
2183 * @cwsseq:	pointer to check and store the clock was set sequence number
2184 * @offs_real:	pointer to storage for monotonic -> realtime offset
2185 * @offs_boot:	pointer to storage for monotonic -> boottime offset
2186 * @offs_tai:	pointer to storage for monotonic -> clock tai offset
2187 *
2188 * Returns current monotonic time and updates the offsets if the
2189 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2190 * different.
2191 *
2192 * Called from hrtimer_interrupt() or retrigger_next_event()
2193 */
2194ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2195				     ktime_t *offs_boot, ktime_t *offs_tai)
2196{
2197	struct timekeeper *tk = &tk_core.timekeeper;
2198	unsigned int seq;
2199	ktime_t base;
2200	u64 nsecs;
2201
2202	do {
2203		seq = read_seqcount_begin(&tk_core.seq);
2204
2205		base = tk->tkr_mono.base;
2206		nsecs = timekeeping_get_ns(&tk->tkr_mono);
2207		base = ktime_add_ns(base, nsecs);
2208
2209		if (*cwsseq != tk->clock_was_set_seq) {
2210			*cwsseq = tk->clock_was_set_seq;
2211			*offs_real = tk->offs_real;
2212			*offs_boot = tk->offs_boot;
2213			*offs_tai = tk->offs_tai;
2214		}
2215
2216		/* Handle leapsecond insertion adjustments */
2217		if (unlikely(base >= tk->next_leap_ktime))
2218			*offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2219
2220	} while (read_seqcount_retry(&tk_core.seq, seq));
2221
2222	return base;
2223}
2224
2225/**
2226 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2227 */
2228static int timekeeping_validate_timex(struct timex *txc)
2229{
2230	if (txc->modes & ADJ_ADJTIME) {
2231		/* singleshot must not be used with any other mode bits */
2232		if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2233			return -EINVAL;
2234		if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2235		    !capable(CAP_SYS_TIME))
2236			return -EPERM;
2237	} else {
2238		/* In order to modify anything, you gotta be super-user! */
2239		if (txc->modes && !capable(CAP_SYS_TIME))
2240			return -EPERM;
2241		/*
2242		 * if the quartz is off by more than 10% then
2243		 * something is VERY wrong!
2244		 */
2245		if (txc->modes & ADJ_TICK &&
2246		    (txc->tick <  900000/USER_HZ ||
2247		     txc->tick > 1100000/USER_HZ))
2248			return -EINVAL;
2249	}
2250
2251	if (txc->modes & ADJ_SETOFFSET) {
2252		/* In order to inject time, you gotta be super-user! */
2253		if (!capable(CAP_SYS_TIME))
2254			return -EPERM;
2255
2256		/*
2257		 * Validate if a timespec/timeval used to inject a time
2258		 * offset is valid.  Offsets can be postive or negative, so
2259		 * we don't check tv_sec. The value of the timeval/timespec
2260		 * is the sum of its fields,but *NOTE*:
2261		 * The field tv_usec/tv_nsec must always be non-negative and
2262		 * we can't have more nanoseconds/microseconds than a second.
2263		 */
2264		if (txc->time.tv_usec < 0)
2265			return -EINVAL;
2266
2267		if (txc->modes & ADJ_NANO) {
2268			if (txc->time.tv_usec >= NSEC_PER_SEC)
2269				return -EINVAL;
2270		} else {
2271			if (txc->time.tv_usec >= USEC_PER_SEC)
2272				return -EINVAL;
2273		}
2274	}
2275
2276	/*
2277	 * Check for potential multiplication overflows that can
2278	 * only happen on 64-bit systems:
2279	 */
2280	if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2281		if (LLONG_MIN / PPM_SCALE > txc->freq)
2282			return -EINVAL;
2283		if (LLONG_MAX / PPM_SCALE < txc->freq)
2284			return -EINVAL;
2285	}
2286
2287	return 0;
2288}
2289
2290
2291/**
2292 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2293 */
2294int do_adjtimex(struct timex *txc)
2295{
2296	struct timekeeper *tk = &tk_core.timekeeper;
2297	unsigned long flags;
2298	struct timespec64 ts;
2299	s32 orig_tai, tai;
2300	int ret;
2301
2302	/* Validate the data before disabling interrupts */
2303	ret = timekeeping_validate_timex(txc);
2304	if (ret)
2305		return ret;
2306
2307	if (txc->modes & ADJ_SETOFFSET) {
2308		struct timespec64 delta;
2309		delta.tv_sec  = txc->time.tv_sec;
2310		delta.tv_nsec = txc->time.tv_usec;
2311		if (!(txc->modes & ADJ_NANO))
2312			delta.tv_nsec *= 1000;
2313		ret = timekeeping_inject_offset(&delta);
2314		if (ret)
2315			return ret;
2316	}
2317
2318	getnstimeofday64(&ts);
2319
2320	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2321	write_seqcount_begin(&tk_core.seq);
2322
2323	orig_tai = tai = tk->tai_offset;
2324	ret = __do_adjtimex(txc, &ts, &tai);
2325
2326	if (tai != orig_tai) {
2327		__timekeeping_set_tai_offset(tk, tai);
2328		timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2329	}
2330	tk_update_leap_state(tk);
2331
2332	write_seqcount_end(&tk_core.seq);
2333	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2334
2335	if (tai != orig_tai)
2336		clock_was_set();
2337
2338	ntp_notify_cmos_timer();
2339
2340	return ret;
2341}
2342
2343#ifdef CONFIG_NTP_PPS
2344/**
2345 * hardpps() - Accessor function to NTP __hardpps function
2346 */
2347void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2348{
2349	unsigned long flags;
2350
2351	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2352	write_seqcount_begin(&tk_core.seq);
2353
2354	__hardpps(phase_ts, raw_ts);
2355
2356	write_seqcount_end(&tk_core.seq);
2357	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 
 
 
2358}
2359EXPORT_SYMBOL(hardpps);
2360#endif /* CONFIG_NTP_PPS */
2361
2362/**
2363 * xtime_update() - advances the timekeeping infrastructure
2364 * @ticks:	number of ticks, that have elapsed since the last call.
2365 *
2366 * Must be called with interrupts disabled.
2367 */
2368void xtime_update(unsigned long ticks)
2369{
2370	write_seqlock(&jiffies_lock);
2371	do_timer(ticks);
2372	write_sequnlock(&jiffies_lock);
2373	update_wall_time();
2374}