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/sched.h>
  18#include <linux/syscore_ops.h>
  19#include <linux/clocksource.h>
  20#include <linux/jiffies.h>
  21#include <linux/time.h>
  22#include <linux/tick.h>
  23#include <linux/stop_machine.h>
  24#include <linux/pvclock_gtod.h>
  25#include <linux/compiler.h>
  26
  27#include "tick-internal.h"
  28#include "ntp_internal.h"
  29#include "timekeeping_internal.h"
  30
  31#define TK_CLEAR_NTP		(1 << 0)
  32#define TK_MIRROR		(1 << 1)
  33#define TK_CLOCK_WAS_SET	(1 << 2)
  34
  35/*
  36 * The most important data for readout fits into a single 64 byte
  37 * cache line.
  38 */
  39static struct {
  40	seqcount_t		seq;
  41	struct timekeeper	timekeeper;
  42} tk_core ____cacheline_aligned;
  43
  44static DEFINE_RAW_SPINLOCK(timekeeper_lock);
  45static struct timekeeper shadow_timekeeper;
  46
  47/**
  48 * struct tk_fast - NMI safe timekeeper
  49 * @seq:	Sequence counter for protecting updates. The lowest bit
  50 *		is the index for the tk_read_base array
  51 * @base:	tk_read_base array. Access is indexed by the lowest bit of
  52 *		@seq.
  53 *
  54 * See @update_fast_timekeeper() below.
  55 */
  56struct tk_fast {
  57	seqcount_t		seq;
  58	struct tk_read_base	base[2];
 
 
 
 
 
 
 
  59};
  60
  61static struct tk_fast tk_fast_mono ____cacheline_aligned;
  62static struct tk_fast tk_fast_raw  ____cacheline_aligned;
  63
  64/* flag for if timekeeping is suspended */
  65int __read_mostly timekeeping_suspended;
  66
  67static inline void tk_normalize_xtime(struct timekeeper *tk)
  68{
  69	while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
  70		tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
  71		tk->xtime_sec++;
  72	}
  73}
  74
  75static inline struct timespec64 tk_xtime(struct timekeeper *tk)
  76{
  77	struct timespec64 ts;
  78
  79	ts.tv_sec = tk->xtime_sec;
  80	ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
  81	return ts;
  82}
  83
  84static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
  85{
  86	tk->xtime_sec = ts->tv_sec;
  87	tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
  88}
  89
  90static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
  91{
  92	tk->xtime_sec += ts->tv_sec;
  93	tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
  94	tk_normalize_xtime(tk);
  95}
  96
  97static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
  98{
  99	struct timespec64 tmp;
 100
 101	/*
 102	 * Verify consistency of: offset_real = -wall_to_monotonic
 103	 * before modifying anything
 104	 */
 105	set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
 106					-tk->wall_to_monotonic.tv_nsec);
 107	WARN_ON_ONCE(tk->offs_real.tv64 != timespec64_to_ktime(tmp).tv64);
 108	tk->wall_to_monotonic = wtm;
 109	set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
 110	tk->offs_real = timespec64_to_ktime(tmp);
 111	tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
 112}
 113
 114static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
 115{
 116	tk->offs_boot = ktime_add(tk->offs_boot, delta);
 117}
 118
 119#ifdef CONFIG_DEBUG_TIMEKEEPING
 120#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
 121
 122static void timekeeping_check_update(struct timekeeper *tk, cycle_t offset)
 123{
 124
 125	cycle_t max_cycles = tk->tkr_mono.clock->max_cycles;
 126	const char *name = tk->tkr_mono.clock->name;
 127
 128	if (offset > max_cycles) {
 129		printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
 130				offset, name, max_cycles);
 131		printk_deferred("         timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
 132	} else {
 133		if (offset > (max_cycles >> 1)) {
 134			printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
 135					offset, name, max_cycles >> 1);
 136			printk_deferred("      timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
 137		}
 138	}
 139
 140	if (tk->underflow_seen) {
 141		if (jiffies - tk->last_warning > WARNING_FREQ) {
 142			printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
 143			printk_deferred("         Please report this, consider using a different clocksource, if possible.\n");
 144			printk_deferred("         Your kernel is probably still fine.\n");
 145			tk->last_warning = jiffies;
 146		}
 147		tk->underflow_seen = 0;
 148	}
 149
 150	if (tk->overflow_seen) {
 151		if (jiffies - tk->last_warning > WARNING_FREQ) {
 152			printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
 153			printk_deferred("         Please report this, consider using a different clocksource, if possible.\n");
 154			printk_deferred("         Your kernel is probably still fine.\n");
 155			tk->last_warning = jiffies;
 156		}
 157		tk->overflow_seen = 0;
 158	}
 159}
 160
 161static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr)
 162{
 163	struct timekeeper *tk = &tk_core.timekeeper;
 164	cycle_t now, last, mask, max, delta;
 165	unsigned int seq;
 166
 167	/*
 168	 * Since we're called holding a seqlock, the data may shift
 169	 * under us while we're doing the calculation. This can cause
 170	 * false positives, since we'd note a problem but throw the
 171	 * results away. So nest another seqlock here to atomically
 172	 * grab the points we are checking with.
 173	 */
 174	do {
 175		seq = read_seqcount_begin(&tk_core.seq);
 176		now = tkr->read(tkr->clock);
 177		last = tkr->cycle_last;
 178		mask = tkr->mask;
 179		max = tkr->clock->max_cycles;
 180	} while (read_seqcount_retry(&tk_core.seq, seq));
 181
 182	delta = clocksource_delta(now, last, mask);
 183
 184	/*
 185	 * Try to catch underflows by checking if we are seeing small
 186	 * mask-relative negative values.
 187	 */
 188	if (unlikely((~delta & mask) < (mask >> 3))) {
 189		tk->underflow_seen = 1;
 190		delta = 0;
 191	}
 192
 193	/* Cap delta value to the max_cycles values to avoid mult overflows */
 194	if (unlikely(delta > max)) {
 195		tk->overflow_seen = 1;
 196		delta = tkr->clock->max_cycles;
 197	}
 198
 199	return delta;
 200}
 201#else
 202static inline void timekeeping_check_update(struct timekeeper *tk, cycle_t offset)
 203{
 204}
 205static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr)
 206{
 207	cycle_t cycle_now, delta;
 208
 209	/* read clocksource */
 210	cycle_now = tkr->read(tkr->clock);
 211
 212	/* calculate the delta since the last update_wall_time */
 213	delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
 214
 215	return delta;
 216}
 217#endif
 218
 219/**
 220 * tk_setup_internals - Set up internals to use clocksource clock.
 221 *
 222 * @tk:		The target timekeeper to setup.
 223 * @clock:		Pointer to clocksource.
 224 *
 225 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
 226 * pair and interval request.
 227 *
 228 * Unless you're the timekeeping code, you should not be using this!
 229 */
 230static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
 231{
 232	cycle_t interval;
 233	u64 tmp, ntpinterval;
 234	struct clocksource *old_clock;
 235
 236	++tk->cs_was_changed_seq;
 237	old_clock = tk->tkr_mono.clock;
 238	tk->tkr_mono.clock = clock;
 239	tk->tkr_mono.read = clock->read;
 240	tk->tkr_mono.mask = clock->mask;
 241	tk->tkr_mono.cycle_last = tk->tkr_mono.read(clock);
 242
 243	tk->tkr_raw.clock = clock;
 244	tk->tkr_raw.read = clock->read;
 245	tk->tkr_raw.mask = clock->mask;
 246	tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
 247
 248	/* Do the ns -> cycle conversion first, using original mult */
 249	tmp = NTP_INTERVAL_LENGTH;
 250	tmp <<= clock->shift;
 251	ntpinterval = tmp;
 252	tmp += clock->mult/2;
 253	do_div(tmp, clock->mult);
 254	if (tmp == 0)
 255		tmp = 1;
 256
 257	interval = (cycle_t) tmp;
 258	tk->cycle_interval = interval;
 259
 260	/* Go back from cycles -> shifted ns */
 261	tk->xtime_interval = (u64) interval * clock->mult;
 262	tk->xtime_remainder = ntpinterval - tk->xtime_interval;
 263	tk->raw_interval =
 264		((u64) interval * clock->mult) >> clock->shift;
 265
 266	 /* if changing clocks, convert xtime_nsec shift units */
 267	if (old_clock) {
 268		int shift_change = clock->shift - old_clock->shift;
 269		if (shift_change < 0)
 270			tk->tkr_mono.xtime_nsec >>= -shift_change;
 271		else
 272			tk->tkr_mono.xtime_nsec <<= shift_change;
 273	}
 274	tk->tkr_raw.xtime_nsec = 0;
 275
 276	tk->tkr_mono.shift = clock->shift;
 277	tk->tkr_raw.shift = clock->shift;
 278
 279	tk->ntp_error = 0;
 280	tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
 281	tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
 282
 283	/*
 284	 * The timekeeper keeps its own mult values for the currently
 285	 * active clocksource. These value will be adjusted via NTP
 286	 * to counteract clock drifting.
 287	 */
 288	tk->tkr_mono.mult = clock->mult;
 289	tk->tkr_raw.mult = clock->mult;
 290	tk->ntp_err_mult = 0;
 291}
 292
 293/* Timekeeper helper functions. */
 294
 295#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
 296static u32 default_arch_gettimeoffset(void) { return 0; }
 297u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
 298#else
 299static inline u32 arch_gettimeoffset(void) { return 0; }
 300#endif
 301
 302static inline s64 timekeeping_delta_to_ns(struct tk_read_base *tkr,
 303					  cycle_t delta)
 304{
 305	s64 nsec;
 306
 307	nsec = delta * tkr->mult + tkr->xtime_nsec;
 308	nsec >>= tkr->shift;
 309
 310	/* If arch requires, add in get_arch_timeoffset() */
 311	return nsec + arch_gettimeoffset();
 312}
 313
 314static inline s64 timekeeping_get_ns(struct tk_read_base *tkr)
 315{
 316	cycle_t delta;
 317
 318	delta = timekeeping_get_delta(tkr);
 319	return timekeeping_delta_to_ns(tkr, delta);
 320}
 321
 322static inline s64 timekeeping_cycles_to_ns(struct tk_read_base *tkr,
 323					    cycle_t cycles)
 324{
 325	cycle_t delta;
 326
 327	/* calculate the delta since the last update_wall_time */
 328	delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
 329	return timekeeping_delta_to_ns(tkr, delta);
 330}
 331
 332/**
 333 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
 334 * @tkr: Timekeeping readout base from which we take the update
 335 *
 336 * We want to use this from any context including NMI and tracing /
 337 * instrumenting the timekeeping code itself.
 338 *
 339 * Employ the latch technique; see @raw_write_seqcount_latch.
 340 *
 341 * So if a NMI hits the update of base[0] then it will use base[1]
 342 * which is still consistent. In the worst case this can result is a
 343 * slightly wrong timestamp (a few nanoseconds). See
 344 * @ktime_get_mono_fast_ns.
 345 */
 346static void update_fast_timekeeper(struct tk_read_base *tkr, struct tk_fast *tkf)
 347{
 348	struct tk_read_base *base = tkf->base;
 349
 350	/* Force readers off to base[1] */
 351	raw_write_seqcount_latch(&tkf->seq);
 352
 353	/* Update base[0] */
 354	memcpy(base, tkr, sizeof(*base));
 355
 356	/* Force readers back to base[0] */
 357	raw_write_seqcount_latch(&tkf->seq);
 358
 359	/* Update base[1] */
 360	memcpy(base + 1, base, sizeof(*base));
 361}
 362
 363/**
 364 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
 365 *
 366 * This timestamp is not guaranteed to be monotonic across an update.
 367 * The timestamp is calculated by:
 368 *
 369 *	now = base_mono + clock_delta * slope
 370 *
 371 * So if the update lowers the slope, readers who are forced to the
 372 * not yet updated second array are still using the old steeper slope.
 373 *
 374 * tmono
 375 * ^
 376 * |    o  n
 377 * |   o n
 378 * |  u
 379 * | o
 380 * |o
 381 * |12345678---> reader order
 382 *
 383 * o = old slope
 384 * u = update
 385 * n = new slope
 386 *
 387 * So reader 6 will observe time going backwards versus reader 5.
 388 *
 389 * While other CPUs are likely to be able observe that, the only way
 390 * for a CPU local observation is when an NMI hits in the middle of
 391 * the update. Timestamps taken from that NMI context might be ahead
 392 * of the following timestamps. Callers need to be aware of that and
 393 * deal with it.
 394 */
 395static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
 396{
 397	struct tk_read_base *tkr;
 398	unsigned int seq;
 399	u64 now;
 400
 401	do {
 402		seq = raw_read_seqcount_latch(&tkf->seq);
 403		tkr = tkf->base + (seq & 0x01);
 404		now = ktime_to_ns(tkr->base) + timekeeping_get_ns(tkr);
 405	} while (read_seqcount_retry(&tkf->seq, seq));
 406
 407	return now;
 408}
 409
 410u64 ktime_get_mono_fast_ns(void)
 411{
 412	return __ktime_get_fast_ns(&tk_fast_mono);
 413}
 414EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
 415
 416u64 ktime_get_raw_fast_ns(void)
 417{
 418	return __ktime_get_fast_ns(&tk_fast_raw);
 419}
 420EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
 421
 422/* Suspend-time cycles value for halted fast timekeeper. */
 423static cycle_t cycles_at_suspend;
 424
 425static cycle_t dummy_clock_read(struct clocksource *cs)
 426{
 427	return cycles_at_suspend;
 428}
 429
 430/**
 431 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
 432 * @tk: Timekeeper to snapshot.
 433 *
 434 * It generally is unsafe to access the clocksource after timekeeping has been
 435 * suspended, so take a snapshot of the readout base of @tk and use it as the
 436 * fast timekeeper's readout base while suspended.  It will return the same
 437 * number of cycles every time until timekeeping is resumed at which time the
 438 * proper readout base for the fast timekeeper will be restored automatically.
 439 */
 440static void halt_fast_timekeeper(struct timekeeper *tk)
 441{
 442	static struct tk_read_base tkr_dummy;
 443	struct tk_read_base *tkr = &tk->tkr_mono;
 444
 445	memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
 446	cycles_at_suspend = tkr->read(tkr->clock);
 447	tkr_dummy.read = dummy_clock_read;
 448	update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
 449
 450	tkr = &tk->tkr_raw;
 451	memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
 452	tkr_dummy.read = dummy_clock_read;
 453	update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
 454}
 455
 456#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
 
 
 457
 458static inline void update_vsyscall(struct timekeeper *tk)
 459{
 460	struct timespec xt, wm;
 461
 462	xt = timespec64_to_timespec(tk_xtime(tk));
 463	wm = timespec64_to_timespec(tk->wall_to_monotonic);
 464	update_vsyscall_old(&xt, &wm, tk->tkr_mono.clock, tk->tkr_mono.mult,
 465			    tk->tkr_mono.cycle_last);
 466}
 467
 468static inline void old_vsyscall_fixup(struct timekeeper *tk)
 469{
 470	s64 remainder;
 471
 472	/*
 473	* Store only full nanoseconds into xtime_nsec after rounding
 474	* it up and add the remainder to the error difference.
 475	* XXX - This is necessary to avoid small 1ns inconsistnecies caused
 476	* by truncating the remainder in vsyscalls. However, it causes
 477	* additional work to be done in timekeeping_adjust(). Once
 478	* the vsyscall implementations are converted to use xtime_nsec
 479	* (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
 480	* users are removed, this can be killed.
 481	*/
 482	remainder = tk->tkr_mono.xtime_nsec & ((1ULL << tk->tkr_mono.shift) - 1);
 483	tk->tkr_mono.xtime_nsec -= remainder;
 484	tk->tkr_mono.xtime_nsec += 1ULL << tk->tkr_mono.shift;
 485	tk->ntp_error += remainder << tk->ntp_error_shift;
 486	tk->ntp_error -= (1ULL << tk->tkr_mono.shift) << tk->ntp_error_shift;
 487}
 488#else
 489#define old_vsyscall_fixup(tk)
 490#endif
 491
 492static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
 493
 494static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
 495{
 496	raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
 497}
 498
 499/**
 500 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
 501 */
 502int pvclock_gtod_register_notifier(struct notifier_block *nb)
 503{
 504	struct timekeeper *tk = &tk_core.timekeeper;
 505	unsigned long flags;
 506	int ret;
 507
 508	raw_spin_lock_irqsave(&timekeeper_lock, flags);
 509	ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
 510	update_pvclock_gtod(tk, true);
 511	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 512
 513	return ret;
 
 514}
 515EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
 516
 517/**
 518 * pvclock_gtod_unregister_notifier - unregister a pvclock
 519 * timedata update listener
 520 */
 521int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
 522{
 523	unsigned long flags;
 524	int ret;
 525
 526	raw_spin_lock_irqsave(&timekeeper_lock, flags);
 527	ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
 528	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 529
 530	return ret;
 531}
 532EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
 533
 534/*
 535 * tk_update_leap_state - helper to update the next_leap_ktime
 536 */
 537static inline void tk_update_leap_state(struct timekeeper *tk)
 538{
 539	tk->next_leap_ktime = ntp_get_next_leap();
 540	if (tk->next_leap_ktime.tv64 != KTIME_MAX)
 541		/* Convert to monotonic time */
 542		tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
 543}
 
 
 
 
 
 
 
 
 544
 545/*
 546 * Update the ktime_t based scalar nsec members of the timekeeper
 547 */
 548static inline void tk_update_ktime_data(struct timekeeper *tk)
 549{
 550	u64 seconds;
 551	u32 nsec;
 552
 553	/*
 554	 * The xtime based monotonic readout is:
 555	 *	nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
 556	 * The ktime based monotonic readout is:
 557	 *	nsec = base_mono + now();
 558	 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
 559	 */
 560	seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
 561	nsec = (u32) tk->wall_to_monotonic.tv_nsec;
 562	tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
 563
 564	/* Update the monotonic raw base */
 565	tk->tkr_raw.base = timespec64_to_ktime(tk->raw_time);
 566
 567	/*
 568	 * The sum of the nanoseconds portions of xtime and
 569	 * wall_to_monotonic can be greater/equal one second. Take
 570	 * this into account before updating tk->ktime_sec.
 571	 */
 572	nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
 573	if (nsec >= NSEC_PER_SEC)
 574		seconds++;
 575	tk->ktime_sec = seconds;
 576}
 577
 578/* must hold timekeeper_lock */
 579static void timekeeping_update(struct timekeeper *tk, unsigned int action)
 580{
 581	if (action & TK_CLEAR_NTP) {
 582		tk->ntp_error = 0;
 583		ntp_clear();
 584	}
 585
 586	tk_update_leap_state(tk);
 587	tk_update_ktime_data(tk);
 588
 589	update_vsyscall(tk);
 590	update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
 591
 592	update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
 593	update_fast_timekeeper(&tk->tkr_raw,  &tk_fast_raw);
 594
 595	if (action & TK_CLOCK_WAS_SET)
 596		tk->clock_was_set_seq++;
 597	/*
 598	 * The mirroring of the data to the shadow-timekeeper needs
 599	 * to happen last here to ensure we don't over-write the
 600	 * timekeeper structure on the next update with stale data
 601	 */
 602	if (action & TK_MIRROR)
 603		memcpy(&shadow_timekeeper, &tk_core.timekeeper,
 604		       sizeof(tk_core.timekeeper));
 605}
 606
 607/**
 608 * timekeeping_forward_now - update clock to the current time
 609 *
 610 * Forward the current clock to update its state since the last call to
 611 * update_wall_time(). This is useful before significant clock changes,
 612 * as it avoids having to deal with this time offset explicitly.
 613 */
 614static void timekeeping_forward_now(struct timekeeper *tk)
 615{
 616	struct clocksource *clock = tk->tkr_mono.clock;
 617	cycle_t cycle_now, delta;
 618	s64 nsec;
 619
 620	cycle_now = tk->tkr_mono.read(clock);
 621	delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
 622	tk->tkr_mono.cycle_last = cycle_now;
 623	tk->tkr_raw.cycle_last  = cycle_now;
 624
 625	tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
 
 626
 627	/* If arch requires, add in get_arch_timeoffset() */
 628	tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
 629
 630	tk_normalize_xtime(tk);
 631
 632	nsec = clocksource_cyc2ns(delta, tk->tkr_raw.mult, tk->tkr_raw.shift);
 633	timespec64_add_ns(&tk->raw_time, nsec);
 634}
 635
 636/**
 637 * __getnstimeofday64 - Returns the time of day in a timespec64.
 638 * @ts:		pointer to the timespec to be set
 639 *
 640 * Updates the time of day in the timespec.
 641 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
 642 */
 643int __getnstimeofday64(struct timespec64 *ts)
 644{
 645	struct timekeeper *tk = &tk_core.timekeeper;
 646	unsigned long seq;
 647	s64 nsecs = 0;
 648
 649	do {
 650		seq = read_seqcount_begin(&tk_core.seq);
 651
 652		ts->tv_sec = tk->xtime_sec;
 653		nsecs = timekeeping_get_ns(&tk->tkr_mono);
 654
 655	} while (read_seqcount_retry(&tk_core.seq, seq));
 656
 657	ts->tv_nsec = 0;
 658	timespec64_add_ns(ts, nsecs);
 659
 660	/*
 661	 * Do not bail out early, in case there were callers still using
 662	 * the value, even in the face of the WARN_ON.
 663	 */
 664	if (unlikely(timekeeping_suspended))
 665		return -EAGAIN;
 666	return 0;
 667}
 668EXPORT_SYMBOL(__getnstimeofday64);
 669
 670/**
 671 * getnstimeofday64 - Returns the time of day in a timespec64.
 672 * @ts:		pointer to the timespec64 to be set
 673 *
 674 * Returns the time of day in a timespec64 (WARN if suspended).
 675 */
 676void getnstimeofday64(struct timespec64 *ts)
 677{
 678	WARN_ON(__getnstimeofday64(ts));
 679}
 680EXPORT_SYMBOL(getnstimeofday64);
 681
 682ktime_t ktime_get(void)
 683{
 684	struct timekeeper *tk = &tk_core.timekeeper;
 685	unsigned int seq;
 686	ktime_t base;
 687	s64 nsecs;
 688
 689	WARN_ON(timekeeping_suspended);
 690
 691	do {
 692		seq = read_seqcount_begin(&tk_core.seq);
 693		base = tk->tkr_mono.base;
 694		nsecs = timekeeping_get_ns(&tk->tkr_mono);
 695
 696	} while (read_seqcount_retry(&tk_core.seq, seq));
 
 697
 698	return ktime_add_ns(base, nsecs);
 699}
 700EXPORT_SYMBOL_GPL(ktime_get);
 701
 702u32 ktime_get_resolution_ns(void)
 703{
 704	struct timekeeper *tk = &tk_core.timekeeper;
 705	unsigned int seq;
 706	u32 nsecs;
 707
 708	WARN_ON(timekeeping_suspended);
 
 709
 710	do {
 711		seq = read_seqcount_begin(&tk_core.seq);
 712		nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
 713	} while (read_seqcount_retry(&tk_core.seq, seq));
 714
 715	return nsecs;
 716}
 717EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
 718
 719static ktime_t *offsets[TK_OFFS_MAX] = {
 720	[TK_OFFS_REAL]	= &tk_core.timekeeper.offs_real,
 721	[TK_OFFS_BOOT]	= &tk_core.timekeeper.offs_boot,
 722	[TK_OFFS_TAI]	= &tk_core.timekeeper.offs_tai,
 723};
 724
 725ktime_t ktime_get_with_offset(enum tk_offsets offs)
 726{
 727	struct timekeeper *tk = &tk_core.timekeeper;
 728	unsigned int seq;
 729	ktime_t base, *offset = offsets[offs];
 730	s64 nsecs;
 731
 732	WARN_ON(timekeeping_suspended);
 733
 734	do {
 735		seq = read_seqcount_begin(&tk_core.seq);
 736		base = ktime_add(tk->tkr_mono.base, *offset);
 737		nsecs = timekeeping_get_ns(&tk->tkr_mono);
 
 738
 739	} while (read_seqcount_retry(&tk_core.seq, seq));
 740
 741	return ktime_add_ns(base, nsecs);
 742
 743}
 744EXPORT_SYMBOL_GPL(ktime_get_with_offset);
 745
 746/**
 747 * ktime_mono_to_any() - convert mononotic time to any other time
 748 * @tmono:	time to convert.
 749 * @offs:	which offset to use
 750 */
 751ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
 752{
 753	ktime_t *offset = offsets[offs];
 754	unsigned long seq;
 755	ktime_t tconv;
 756
 757	do {
 758		seq = read_seqcount_begin(&tk_core.seq);
 759		tconv = ktime_add(tmono, *offset);
 760	} while (read_seqcount_retry(&tk_core.seq, seq));
 761
 762	return tconv;
 763}
 764EXPORT_SYMBOL_GPL(ktime_mono_to_any);
 765
 766/**
 767 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
 768 */
 769ktime_t ktime_get_raw(void)
 770{
 771	struct timekeeper *tk = &tk_core.timekeeper;
 772	unsigned int seq;
 773	ktime_t base;
 774	s64 nsecs;
 775
 776	do {
 777		seq = read_seqcount_begin(&tk_core.seq);
 778		base = tk->tkr_raw.base;
 779		nsecs = timekeeping_get_ns(&tk->tkr_raw);
 780
 781	} while (read_seqcount_retry(&tk_core.seq, seq));
 782
 783	return ktime_add_ns(base, nsecs);
 784}
 785EXPORT_SYMBOL_GPL(ktime_get_raw);
 786
 787/**
 788 * ktime_get_ts64 - get the monotonic clock in timespec64 format
 789 * @ts:		pointer to timespec variable
 790 *
 791 * The function calculates the monotonic clock from the realtime
 792 * clock and the wall_to_monotonic offset and stores the result
 793 * in normalized timespec64 format in the variable pointed to by @ts.
 794 */
 795void ktime_get_ts64(struct timespec64 *ts)
 796{
 797	struct timekeeper *tk = &tk_core.timekeeper;
 798	struct timespec64 tomono;
 799	s64 nsec;
 800	unsigned int seq;
 
 801
 802	WARN_ON(timekeeping_suspended);
 803
 804	do {
 805		seq = read_seqcount_begin(&tk_core.seq);
 806		ts->tv_sec = tk->xtime_sec;
 807		nsec = timekeeping_get_ns(&tk->tkr_mono);
 808		tomono = tk->wall_to_monotonic;
 809
 810	} while (read_seqcount_retry(&tk_core.seq, seq));
 811
 812	ts->tv_sec += tomono.tv_sec;
 813	ts->tv_nsec = 0;
 814	timespec64_add_ns(ts, nsec + tomono.tv_nsec);
 815}
 816EXPORT_SYMBOL_GPL(ktime_get_ts64);
 817
 818/**
 819 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
 820 *
 821 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
 822 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
 823 * works on both 32 and 64 bit systems. On 32 bit systems the readout
 824 * covers ~136 years of uptime which should be enough to prevent
 825 * premature wrap arounds.
 826 */
 827time64_t ktime_get_seconds(void)
 828{
 829	struct timekeeper *tk = &tk_core.timekeeper;
 830
 831	WARN_ON(timekeeping_suspended);
 832	return tk->ktime_sec;
 833}
 834EXPORT_SYMBOL_GPL(ktime_get_seconds);
 835
 836/**
 837 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
 838 *
 839 * Returns the wall clock seconds since 1970. This replaces the
 840 * get_seconds() interface which is not y2038 safe on 32bit systems.
 841 *
 842 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
 843 * 32bit systems the access must be protected with the sequence
 844 * counter to provide "atomic" access to the 64bit tk->xtime_sec
 845 * value.
 846 */
 847time64_t ktime_get_real_seconds(void)
 848{
 849	struct timekeeper *tk = &tk_core.timekeeper;
 850	time64_t seconds;
 851	unsigned int seq;
 852
 853	if (IS_ENABLED(CONFIG_64BIT))
 854		return tk->xtime_sec;
 855
 856	do {
 857		seq = read_seqcount_begin(&tk_core.seq);
 858		seconds = tk->xtime_sec;
 859
 860	} while (read_seqcount_retry(&tk_core.seq, seq));
 861
 862	return seconds;
 
 863}
 864EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
 865
 866/**
 867 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
 868 * but without the sequence counter protect. This internal function
 869 * is called just when timekeeping lock is already held.
 870 */
 871time64_t __ktime_get_real_seconds(void)
 872{
 873	struct timekeeper *tk = &tk_core.timekeeper;
 874
 875	return tk->xtime_sec;
 876}
 877
 878/**
 879 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
 880 * @systime_snapshot:	pointer to struct receiving the system time snapshot
 
 
 
 
 
 881 */
 882void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 883{
 884	struct timekeeper *tk = &tk_core.timekeeper;
 885	unsigned long seq;
 886	ktime_t base_raw;
 887	ktime_t base_real;
 888	s64 nsec_raw;
 889	s64 nsec_real;
 890	cycle_t now;
 891
 892	WARN_ON_ONCE(timekeeping_suspended);
 893
 894	do {
 895		seq = read_seqcount_begin(&tk_core.seq);
 896
 897		now = tk->tkr_mono.read(tk->tkr_mono.clock);
 898		systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
 899		systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
 900		base_real = ktime_add(tk->tkr_mono.base,
 901				      tk_core.timekeeper.offs_real);
 902		base_raw = tk->tkr_raw.base;
 903		nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
 904		nsec_raw  = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
 905	} while (read_seqcount_retry(&tk_core.seq, seq));
 906
 907	systime_snapshot->cycles = now;
 908	systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
 909	systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
 910}
 911EXPORT_SYMBOL_GPL(ktime_get_snapshot);
 912
 913/* Scale base by mult/div checking for overflow */
 914static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
 915{
 916	u64 tmp, rem;
 917
 918	tmp = div64_u64_rem(*base, div, &rem);
 919
 920	if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
 921	    ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
 922		return -EOVERFLOW;
 923	tmp *= mult;
 924	rem *= mult;
 925
 926	do_div(rem, div);
 927	*base = tmp + rem;
 928	return 0;
 929}
 930
 931/**
 932 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
 933 * @history:			Snapshot representing start of history
 934 * @partial_history_cycles:	Cycle offset into history (fractional part)
 935 * @total_history_cycles:	Total history length in cycles
 936 * @discontinuity:		True indicates clock was set on history period
 937 * @ts:				Cross timestamp that should be adjusted using
 938 *	partial/total ratio
 939 *
 940 * Helper function used by get_device_system_crosststamp() to correct the
 941 * crosstimestamp corresponding to the start of the current interval to the
 942 * system counter value (timestamp point) provided by the driver. The
 943 * total_history_* quantities are the total history starting at the provided
 944 * reference point and ending at the start of the current interval. The cycle
 945 * count between the driver timestamp point and the start of the current
 946 * interval is partial_history_cycles.
 947 */
 948static int adjust_historical_crosststamp(struct system_time_snapshot *history,
 949					 cycle_t partial_history_cycles,
 950					 cycle_t total_history_cycles,
 951					 bool discontinuity,
 952					 struct system_device_crosststamp *ts)
 953{
 954	struct timekeeper *tk = &tk_core.timekeeper;
 955	u64 corr_raw, corr_real;
 956	bool interp_forward;
 957	int ret;
 958
 959	if (total_history_cycles == 0 || partial_history_cycles == 0)
 960		return 0;
 961
 962	/* Interpolate shortest distance from beginning or end of history */
 963	interp_forward = partial_history_cycles > total_history_cycles/2 ?
 964		true : false;
 965	partial_history_cycles = interp_forward ?
 966		total_history_cycles - partial_history_cycles :
 967		partial_history_cycles;
 968
 969	/*
 970	 * Scale the monotonic raw time delta by:
 971	 *	partial_history_cycles / total_history_cycles
 972	 */
 973	corr_raw = (u64)ktime_to_ns(
 974		ktime_sub(ts->sys_monoraw, history->raw));
 975	ret = scale64_check_overflow(partial_history_cycles,
 976				     total_history_cycles, &corr_raw);
 977	if (ret)
 978		return ret;
 979
 980	/*
 981	 * If there is a discontinuity in the history, scale monotonic raw
 982	 *	correction by:
 983	 *	mult(real)/mult(raw) yielding the realtime correction
 984	 * Otherwise, calculate the realtime correction similar to monotonic
 985	 *	raw calculation
 986	 */
 987	if (discontinuity) {
 988		corr_real = mul_u64_u32_div
 989			(corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
 990	} else {
 991		corr_real = (u64)ktime_to_ns(
 992			ktime_sub(ts->sys_realtime, history->real));
 993		ret = scale64_check_overflow(partial_history_cycles,
 994					     total_history_cycles, &corr_real);
 995		if (ret)
 996			return ret;
 997	}
 998
 999	/* Fixup monotonic raw and real time time values */
1000	if (interp_forward) {
1001		ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1002		ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1003	} else {
1004		ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1005		ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1006	}
1007
1008	return 0;
1009}
1010
1011/*
1012 * cycle_between - true if test occurs chronologically between before and after
1013 */
1014static bool cycle_between(cycle_t before, cycle_t test, cycle_t after)
1015{
1016	if (test > before && test < after)
1017		return true;
1018	if (test < before && before > after)
1019		return true;
1020	return false;
1021}
 
1022
1023/**
1024 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1025 * @get_time_fn:	Callback to get simultaneous device time and
1026 *	system counter from the device driver
1027 * @ctx:		Context passed to get_time_fn()
1028 * @history_begin:	Historical reference point used to interpolate system
1029 *	time when counter provided by the driver is before the current interval
1030 * @xtstamp:		Receives simultaneously captured system and device time
1031 *
1032 * Reads a timestamp from a device and correlates it to system time
1033 */
1034int get_device_system_crosststamp(int (*get_time_fn)
1035				  (ktime_t *device_time,
1036				   struct system_counterval_t *sys_counterval,
1037				   void *ctx),
1038				  void *ctx,
1039				  struct system_time_snapshot *history_begin,
1040				  struct system_device_crosststamp *xtstamp)
1041{
1042	struct system_counterval_t system_counterval;
1043	struct timekeeper *tk = &tk_core.timekeeper;
1044	cycle_t cycles, now, interval_start;
1045	unsigned int clock_was_set_seq = 0;
1046	ktime_t base_real, base_raw;
1047	s64 nsec_real, nsec_raw;
1048	u8 cs_was_changed_seq;
1049	unsigned long seq;
1050	bool do_interp;
1051	int ret;
1052
1053	do {
1054		seq = read_seqcount_begin(&tk_core.seq);
1055		/*
1056		 * Try to synchronously capture device time and a system
1057		 * counter value calling back into the device driver
1058		 */
1059		ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1060		if (ret)
1061			return ret;
1062
1063		/*
1064		 * Verify that the clocksource associated with the captured
1065		 * system counter value is the same as the currently installed
1066		 * timekeeper clocksource
1067		 */
1068		if (tk->tkr_mono.clock != system_counterval.cs)
1069			return -ENODEV;
1070		cycles = system_counterval.cycles;
1071
1072		/*
1073		 * Check whether the system counter value provided by the
1074		 * device driver is on the current timekeeping interval.
1075		 */
1076		now = tk->tkr_mono.read(tk->tkr_mono.clock);
1077		interval_start = tk->tkr_mono.cycle_last;
1078		if (!cycle_between(interval_start, cycles, now)) {
1079			clock_was_set_seq = tk->clock_was_set_seq;
1080			cs_was_changed_seq = tk->cs_was_changed_seq;
1081			cycles = interval_start;
1082			do_interp = true;
1083		} else {
1084			do_interp = false;
1085		}
1086
1087		base_real = ktime_add(tk->tkr_mono.base,
1088				      tk_core.timekeeper.offs_real);
1089		base_raw = tk->tkr_raw.base;
1090
1091		nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1092						     system_counterval.cycles);
1093		nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1094						    system_counterval.cycles);
1095	} while (read_seqcount_retry(&tk_core.seq, seq));
1096
1097	xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1098	xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1099
1100	/*
1101	 * Interpolate if necessary, adjusting back from the start of the
1102	 * current interval
1103	 */
1104	if (do_interp) {
1105		cycle_t partial_history_cycles, total_history_cycles;
1106		bool discontinuity;
1107
1108		/*
1109		 * Check that the counter value occurs after the provided
1110		 * history reference and that the history doesn't cross a
1111		 * clocksource change
1112		 */
1113		if (!history_begin ||
1114		    !cycle_between(history_begin->cycles,
1115				   system_counterval.cycles, cycles) ||
1116		    history_begin->cs_was_changed_seq != cs_was_changed_seq)
1117			return -EINVAL;
1118		partial_history_cycles = cycles - system_counterval.cycles;
1119		total_history_cycles = cycles - history_begin->cycles;
1120		discontinuity =
1121			history_begin->clock_was_set_seq != clock_was_set_seq;
1122
1123		ret = adjust_historical_crosststamp(history_begin,
1124						    partial_history_cycles,
1125						    total_history_cycles,
1126						    discontinuity, xtstamp);
1127		if (ret)
1128			return ret;
1129	}
1130
1131	return 0;
1132}
1133EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1134
1135/**
1136 * do_gettimeofday - Returns the time of day in a timeval
1137 * @tv:		pointer to the timeval to be set
1138 *
1139 * NOTE: Users should be converted to using getnstimeofday()
1140 */
1141void do_gettimeofday(struct timeval *tv)
1142{
1143	struct timespec64 now;
1144
1145	getnstimeofday64(&now);
1146	tv->tv_sec = now.tv_sec;
1147	tv->tv_usec = now.tv_nsec/1000;
1148}
1149EXPORT_SYMBOL(do_gettimeofday);
1150
 
1151/**
1152 * do_settimeofday64 - Sets the time of day.
1153 * @ts:     pointer to the timespec64 variable containing the new time
1154 *
1155 * Sets the time of day to the new time and update NTP and notify hrtimers
1156 */
1157int do_settimeofday64(const struct timespec64 *ts)
1158{
1159	struct timekeeper *tk = &tk_core.timekeeper;
1160	struct timespec64 ts_delta, xt;
1161	unsigned long flags;
1162	int ret = 0;
1163
1164	if (!timespec64_valid_strict(ts))
1165		return -EINVAL;
1166
1167	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1168	write_seqcount_begin(&tk_core.seq);
1169
1170	timekeeping_forward_now(tk);
1171
1172	xt = tk_xtime(tk);
1173	ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1174	ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1175
1176	if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1177		ret = -EINVAL;
1178		goto out;
1179	}
1180
1181	tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
 
1182
1183	tk_set_xtime(tk, ts);
1184out:
1185	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1186
1187	write_seqcount_end(&tk_core.seq);
1188	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1189
1190	/* signal hrtimers about time change */
1191	clock_was_set();
1192
1193	return ret;
1194}
1195EXPORT_SYMBOL(do_settimeofday64);
 
 
1196
1197/**
1198 * timekeeping_inject_offset - Adds or subtracts from the current time.
1199 * @tv:		pointer to the timespec variable containing the offset
1200 *
1201 * Adds or subtracts an offset value from the current time.
1202 */
1203int timekeeping_inject_offset(struct timespec *ts)
1204{
1205	struct timekeeper *tk = &tk_core.timekeeper;
1206	unsigned long flags;
1207	struct timespec64 ts64, tmp;
1208	int ret = 0;
1209
1210	if (!timespec_inject_offset_valid(ts))
1211		return -EINVAL;
1212
1213	ts64 = timespec_to_timespec64(*ts);
1214
1215	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1216	write_seqcount_begin(&tk_core.seq);
1217
1218	timekeeping_forward_now(tk);
1219
1220	/* Make sure the proposed value is valid */
1221	tmp = timespec64_add(tk_xtime(tk),  ts64);
1222	if (timespec64_compare(&tk->wall_to_monotonic, &ts64) > 0 ||
1223	    !timespec64_valid_strict(&tmp)) {
1224		ret = -EINVAL;
1225		goto error;
1226	}
1227
1228	tk_xtime_add(tk, &ts64);
1229	tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts64));
1230
1231error: /* even if we error out, we forwarded the time, so call update */
1232	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1233
1234	write_seqcount_end(&tk_core.seq);
1235	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1236
1237	/* signal hrtimers about time change */
1238	clock_was_set();
1239
1240	return ret;
1241}
1242EXPORT_SYMBOL(timekeeping_inject_offset);
1243
1244
1245/**
1246 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
1247 *
1248 */
1249s32 timekeeping_get_tai_offset(void)
1250{
1251	struct timekeeper *tk = &tk_core.timekeeper;
1252	unsigned int seq;
1253	s32 ret;
1254
1255	do {
1256		seq = read_seqcount_begin(&tk_core.seq);
1257		ret = tk->tai_offset;
1258	} while (read_seqcount_retry(&tk_core.seq, seq));
1259
1260	return ret;
1261}
1262
1263/**
1264 * __timekeeping_set_tai_offset - Lock free worker function
1265 *
1266 */
1267static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1268{
1269	tk->tai_offset = tai_offset;
1270	tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1271}
1272
1273/**
1274 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
1275 *
1276 */
1277void timekeeping_set_tai_offset(s32 tai_offset)
1278{
1279	struct timekeeper *tk = &tk_core.timekeeper;
1280	unsigned long flags;
1281
1282	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1283	write_seqcount_begin(&tk_core.seq);
1284	__timekeeping_set_tai_offset(tk, tai_offset);
1285	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1286	write_seqcount_end(&tk_core.seq);
1287	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1288	clock_was_set();
1289}
1290
1291/**
1292 * change_clocksource - Swaps clocksources if a new one is available
1293 *
1294 * Accumulates current time interval and initializes new clocksource
1295 */
1296static int change_clocksource(void *data)
1297{
1298	struct timekeeper *tk = &tk_core.timekeeper;
1299	struct clocksource *new, *old;
1300	unsigned long flags;
1301
1302	new = (struct clocksource *) data;
1303
1304	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1305	write_seqcount_begin(&tk_core.seq);
1306
1307	timekeeping_forward_now(tk);
1308	/*
1309	 * If the cs is in module, get a module reference. Succeeds
1310	 * for built-in code (owner == NULL) as well.
1311	 */
1312	if (try_module_get(new->owner)) {
1313		if (!new->enable || new->enable(new) == 0) {
1314			old = tk->tkr_mono.clock;
1315			tk_setup_internals(tk, new);
1316			if (old->disable)
1317				old->disable(old);
1318			module_put(old->owner);
1319		} else {
1320			module_put(new->owner);
1321		}
1322	}
1323	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1324
1325	write_seqcount_end(&tk_core.seq);
1326	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1327
1328	return 0;
1329}
1330
1331/**
1332 * timekeeping_notify - Install a new clock source
1333 * @clock:		pointer to the clock source
1334 *
1335 * This function is called from clocksource.c after a new, better clock
1336 * source has been registered. The caller holds the clocksource_mutex.
1337 */
1338int timekeeping_notify(struct clocksource *clock)
1339{
1340	struct timekeeper *tk = &tk_core.timekeeper;
1341
1342	if (tk->tkr_mono.clock == clock)
1343		return 0;
1344	stop_machine(change_clocksource, clock, NULL);
1345	tick_clock_notify();
1346	return tk->tkr_mono.clock == clock ? 0 : -1;
1347}
1348
1349/**
1350 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
1351 * @ts:		pointer to the timespec64 to be set
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1352 *
1353 * Returns the raw monotonic time (completely un-modified by ntp)
1354 */
1355void getrawmonotonic64(struct timespec64 *ts)
1356{
1357	struct timekeeper *tk = &tk_core.timekeeper;
1358	struct timespec64 ts64;
1359	unsigned long seq;
1360	s64 nsecs;
1361
1362	do {
1363		seq = read_seqcount_begin(&tk_core.seq);
1364		nsecs = timekeeping_get_ns(&tk->tkr_raw);
1365		ts64 = tk->raw_time;
1366
1367	} while (read_seqcount_retry(&tk_core.seq, seq));
1368
1369	timespec64_add_ns(&ts64, nsecs);
1370	*ts = ts64;
1371}
1372EXPORT_SYMBOL(getrawmonotonic64);
1373
1374
1375/**
1376 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1377 */
1378int timekeeping_valid_for_hres(void)
1379{
1380	struct timekeeper *tk = &tk_core.timekeeper;
1381	unsigned long seq;
1382	int ret;
1383
1384	do {
1385		seq = read_seqcount_begin(&tk_core.seq);
1386
1387		ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1388
1389	} while (read_seqcount_retry(&tk_core.seq, seq));
1390
1391	return ret;
1392}
1393
1394/**
1395 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
 
 
 
1396 */
1397u64 timekeeping_max_deferment(void)
1398{
1399	struct timekeeper *tk = &tk_core.timekeeper;
1400	unsigned long seq;
1401	u64 ret;
1402
1403	do {
1404		seq = read_seqcount_begin(&tk_core.seq);
1405
1406		ret = tk->tkr_mono.clock->max_idle_ns;
1407
1408	} while (read_seqcount_retry(&tk_core.seq, seq));
1409
1410	return ret;
1411}
1412
1413/**
1414 * read_persistent_clock -  Return time from the persistent clock.
1415 *
1416 * Weak dummy function for arches that do not yet support it.
1417 * Reads the time from the battery backed persistent clock.
1418 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1419 *
1420 *  XXX - Do be sure to remove it once all arches implement it.
1421 */
1422void __weak read_persistent_clock(struct timespec *ts)
1423{
1424	ts->tv_sec = 0;
1425	ts->tv_nsec = 0;
1426}
1427
1428void __weak read_persistent_clock64(struct timespec64 *ts64)
1429{
1430	struct timespec ts;
1431
1432	read_persistent_clock(&ts);
1433	*ts64 = timespec_to_timespec64(ts);
1434}
1435
1436/**
1437 * read_boot_clock64 -  Return time of the system start.
1438 *
1439 * Weak dummy function for arches that do not yet support it.
1440 * Function to read the exact time the system has been started.
1441 * Returns a timespec64 with tv_sec=0 and tv_nsec=0 if unsupported.
1442 *
1443 *  XXX - Do be sure to remove it once all arches implement it.
1444 */
1445void __weak read_boot_clock64(struct timespec64 *ts)
1446{
1447	ts->tv_sec = 0;
1448	ts->tv_nsec = 0;
1449}
1450
1451/* Flag for if timekeeping_resume() has injected sleeptime */
1452static bool sleeptime_injected;
1453
1454/* Flag for if there is a persistent clock on this platform */
1455static bool persistent_clock_exists;
1456
1457/*
1458 * timekeeping_init - Initializes the clocksource and common timekeeping values
1459 */
1460void __init timekeeping_init(void)
1461{
1462	struct timekeeper *tk = &tk_core.timekeeper;
1463	struct clocksource *clock;
1464	unsigned long flags;
1465	struct timespec64 now, boot, tmp;
1466
1467	read_persistent_clock64(&now);
1468	if (!timespec64_valid_strict(&now)) {
1469		pr_warn("WARNING: Persistent clock returned invalid value!\n"
1470			"         Check your CMOS/BIOS settings.\n");
1471		now.tv_sec = 0;
1472		now.tv_nsec = 0;
1473	} else if (now.tv_sec || now.tv_nsec)
1474		persistent_clock_exists = true;
1475
1476	read_boot_clock64(&boot);
1477	if (!timespec64_valid_strict(&boot)) {
1478		pr_warn("WARNING: Boot clock returned invalid value!\n"
1479			"         Check your CMOS/BIOS settings.\n");
1480		boot.tv_sec = 0;
1481		boot.tv_nsec = 0;
1482	}
1483
1484	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1485	write_seqcount_begin(&tk_core.seq);
1486	ntp_init();
1487
1488	clock = clocksource_default_clock();
1489	if (clock->enable)
1490		clock->enable(clock);
1491	tk_setup_internals(tk, clock);
1492
1493	tk_set_xtime(tk, &now);
1494	tk->raw_time.tv_sec = 0;
1495	tk->raw_time.tv_nsec = 0;
1496	if (boot.tv_sec == 0 && boot.tv_nsec == 0)
1497		boot = tk_xtime(tk);
1498
1499	set_normalized_timespec64(&tmp, -boot.tv_sec, -boot.tv_nsec);
1500	tk_set_wall_to_mono(tk, tmp);
1501
1502	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1503
1504	write_seqcount_end(&tk_core.seq);
1505	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1506}
1507
1508/* time in seconds when suspend began for persistent clock */
1509static struct timespec64 timekeeping_suspend_time;
1510
1511/**
1512 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1513 * @delta: pointer to a timespec delta value
1514 *
1515 * Takes a timespec offset measuring a suspend interval and properly
1516 * adds the sleep offset to the timekeeping variables.
1517 */
1518static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1519					   struct timespec64 *delta)
1520{
1521	if (!timespec64_valid_strict(delta)) {
1522		printk_deferred(KERN_WARNING
1523				"__timekeeping_inject_sleeptime: Invalid "
1524				"sleep delta value!\n");
1525		return;
1526	}
1527	tk_xtime_add(tk, delta);
1528	tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1529	tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1530	tk_debug_account_sleep_time(delta);
1531}
1532
1533#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1534/**
1535 * We have three kinds of time sources to use for sleep time
1536 * injection, the preference order is:
1537 * 1) non-stop clocksource
1538 * 2) persistent clock (ie: RTC accessible when irqs are off)
1539 * 3) RTC
1540 *
1541 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1542 * If system has neither 1) nor 2), 3) will be used finally.
1543 *
1544 *
1545 * If timekeeping has injected sleeptime via either 1) or 2),
1546 * 3) becomes needless, so in this case we don't need to call
1547 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1548 * means.
1549 */
1550bool timekeeping_rtc_skipresume(void)
1551{
1552	return sleeptime_injected;
1553}
1554
1555/**
1556 * 1) can be determined whether to use or not only when doing
1557 * timekeeping_resume() which is invoked after rtc_suspend(),
1558 * so we can't skip rtc_suspend() surely if system has 1).
1559 *
1560 * But if system has 2), 2) will definitely be used, so in this
1561 * case we don't need to call rtc_suspend(), and this is what
1562 * timekeeping_rtc_skipsuspend() means.
1563 */
1564bool timekeeping_rtc_skipsuspend(void)
1565{
1566	return persistent_clock_exists;
1567}
1568
1569/**
1570 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1571 * @delta: pointer to a timespec64 delta value
1572 *
1573 * This hook is for architectures that cannot support read_persistent_clock64
1574 * because their RTC/persistent clock is only accessible when irqs are enabled.
1575 * and also don't have an effective nonstop clocksource.
1576 *
1577 * This function should only be called by rtc_resume(), and allows
1578 * a suspend offset to be injected into the timekeeping values.
1579 */
1580void timekeeping_inject_sleeptime64(struct timespec64 *delta)
1581{
1582	struct timekeeper *tk = &tk_core.timekeeper;
1583	unsigned long flags;
 
1584
1585	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1586	write_seqcount_begin(&tk_core.seq);
 
 
1587
1588	timekeeping_forward_now(tk);
 
1589
1590	__timekeeping_inject_sleeptime(tk, delta);
1591
1592	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
 
 
 
1593
1594	write_seqcount_end(&tk_core.seq);
1595	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1596
1597	/* signal hrtimers about time change */
1598	clock_was_set();
1599}
1600#endif
1601
1602/**
1603 * timekeeping_resume - Resumes the generic timekeeping subsystem.
 
 
 
 
1604 */
1605void timekeeping_resume(void)
1606{
1607	struct timekeeper *tk = &tk_core.timekeeper;
1608	struct clocksource *clock = tk->tkr_mono.clock;
1609	unsigned long flags;
1610	struct timespec64 ts_new, ts_delta;
1611	cycle_t cycle_now, cycle_delta;
1612
1613	sleeptime_injected = false;
1614	read_persistent_clock64(&ts_new);
1615
1616	clockevents_resume();
1617	clocksource_resume();
1618
1619	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1620	write_seqcount_begin(&tk_core.seq);
1621
1622	/*
1623	 * After system resumes, we need to calculate the suspended time and
1624	 * compensate it for the OS time. There are 3 sources that could be
1625	 * used: Nonstop clocksource during suspend, persistent clock and rtc
1626	 * device.
1627	 *
1628	 * One specific platform may have 1 or 2 or all of them, and the
1629	 * preference will be:
1630	 *	suspend-nonstop clocksource -> persistent clock -> rtc
1631	 * The less preferred source will only be tried if there is no better
1632	 * usable source. The rtc part is handled separately in rtc core code.
1633	 */
1634	cycle_now = tk->tkr_mono.read(clock);
1635	if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
1636		cycle_now > tk->tkr_mono.cycle_last) {
1637		u64 num, max = ULLONG_MAX;
1638		u32 mult = clock->mult;
1639		u32 shift = clock->shift;
1640		s64 nsec = 0;
1641
1642		cycle_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last,
1643						tk->tkr_mono.mask);
1644
1645		/*
1646		 * "cycle_delta * mutl" may cause 64 bits overflow, if the
1647		 * suspended time is too long. In that case we need do the
1648		 * 64 bits math carefully
1649		 */
1650		do_div(max, mult);
1651		if (cycle_delta > max) {
1652			num = div64_u64(cycle_delta, max);
1653			nsec = (((u64) max * mult) >> shift) * num;
1654			cycle_delta -= num * max;
1655		}
1656		nsec += ((u64) cycle_delta * mult) >> shift;
1657
1658		ts_delta = ns_to_timespec64(nsec);
1659		sleeptime_injected = true;
1660	} else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1661		ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1662		sleeptime_injected = true;
1663	}
1664
1665	if (sleeptime_injected)
1666		__timekeeping_inject_sleeptime(tk, &ts_delta);
1667
1668	/* Re-base the last cycle value */
1669	tk->tkr_mono.cycle_last = cycle_now;
1670	tk->tkr_raw.cycle_last  = cycle_now;
1671
1672	tk->ntp_error = 0;
 
 
 
 
 
 
1673	timekeeping_suspended = 0;
1674	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1675	write_seqcount_end(&tk_core.seq);
1676	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1677
1678	touch_softlockup_watchdog();
1679
1680	tick_resume();
 
 
1681	hrtimers_resume();
1682}
1683
1684int timekeeping_suspend(void)
1685{
1686	struct timekeeper *tk = &tk_core.timekeeper;
1687	unsigned long flags;
1688	struct timespec64		delta, delta_delta;
1689	static struct timespec64	old_delta;
1690
1691	read_persistent_clock64(&timekeeping_suspend_time);
1692
1693	/*
1694	 * On some systems the persistent_clock can not be detected at
1695	 * timekeeping_init by its return value, so if we see a valid
1696	 * value returned, update the persistent_clock_exists flag.
1697	 */
1698	if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1699		persistent_clock_exists = true;
1700
1701	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1702	write_seqcount_begin(&tk_core.seq);
1703	timekeeping_forward_now(tk);
1704	timekeeping_suspended = 1;
1705
1706	if (persistent_clock_exists) {
 
 
 
 
 
 
 
 
1707		/*
1708		 * To avoid drift caused by repeated suspend/resumes,
1709		 * which each can add ~1 second drift error,
1710		 * try to compensate so the difference in system time
1711		 * and persistent_clock time stays close to constant.
1712		 */
1713		delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1714		delta_delta = timespec64_sub(delta, old_delta);
1715		if (abs(delta_delta.tv_sec) >= 2) {
1716			/*
1717			 * if delta_delta is too large, assume time correction
1718			 * has occurred and set old_delta to the current delta.
1719			 */
1720			old_delta = delta;
1721		} else {
1722			/* Otherwise try to adjust old_system to compensate */
1723			timekeeping_suspend_time =
1724				timespec64_add(timekeeping_suspend_time, delta_delta);
1725		}
1726	}
 
1727
1728	timekeeping_update(tk, TK_MIRROR);
1729	halt_fast_timekeeper(tk);
1730	write_seqcount_end(&tk_core.seq);
1731	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1732
1733	tick_suspend();
1734	clocksource_suspend();
1735	clockevents_suspend();
1736
1737	return 0;
1738}
1739
1740/* sysfs resume/suspend bits for timekeeping */
1741static struct syscore_ops timekeeping_syscore_ops = {
1742	.resume		= timekeeping_resume,
1743	.suspend	= timekeeping_suspend,
1744};
1745
1746static int __init timekeeping_init_ops(void)
1747{
1748	register_syscore_ops(&timekeeping_syscore_ops);
1749	return 0;
1750}
1751device_initcall(timekeeping_init_ops);
1752
1753/*
1754 * Apply a multiplier adjustment to the timekeeper
1755 */
1756static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1757							 s64 offset,
1758							 bool negative,
1759							 int adj_scale)
1760{
1761	s64 interval = tk->cycle_interval;
1762	s32 mult_adj = 1;
1763
1764	if (negative) {
1765		mult_adj = -mult_adj;
1766		interval = -interval;
1767		offset  = -offset;
1768	}
1769	mult_adj <<= adj_scale;
1770	interval <<= adj_scale;
1771	offset <<= adj_scale;
1772
1773	/*
1774	 * So the following can be confusing.
1775	 *
1776	 * To keep things simple, lets assume mult_adj == 1 for now.
1777	 *
1778	 * When mult_adj != 1, remember that the interval and offset values
1779	 * have been appropriately scaled so the math is the same.
1780	 *
1781	 * The basic idea here is that we're increasing the multiplier
1782	 * by one, this causes the xtime_interval to be incremented by
1783	 * one cycle_interval. This is because:
1784	 *	xtime_interval = cycle_interval * mult
1785	 * So if mult is being incremented by one:
1786	 *	xtime_interval = cycle_interval * (mult + 1)
1787	 * Its the same as:
1788	 *	xtime_interval = (cycle_interval * mult) + cycle_interval
1789	 * Which can be shortened to:
1790	 *	xtime_interval += cycle_interval
1791	 *
1792	 * So offset stores the non-accumulated cycles. Thus the current
1793	 * time (in shifted nanoseconds) is:
1794	 *	now = (offset * adj) + xtime_nsec
1795	 * Now, even though we're adjusting the clock frequency, we have
1796	 * to keep time consistent. In other words, we can't jump back
1797	 * in time, and we also want to avoid jumping forward in time.
1798	 *
1799	 * So given the same offset value, we need the time to be the same
1800	 * both before and after the freq adjustment.
1801	 *	now = (offset * adj_1) + xtime_nsec_1
1802	 *	now = (offset * adj_2) + xtime_nsec_2
1803	 * So:
1804	 *	(offset * adj_1) + xtime_nsec_1 =
1805	 *		(offset * adj_2) + xtime_nsec_2
1806	 * And we know:
1807	 *	adj_2 = adj_1 + 1
1808	 * So:
1809	 *	(offset * adj_1) + xtime_nsec_1 =
1810	 *		(offset * (adj_1+1)) + xtime_nsec_2
1811	 *	(offset * adj_1) + xtime_nsec_1 =
1812	 *		(offset * adj_1) + offset + xtime_nsec_2
1813	 * Canceling the sides:
1814	 *	xtime_nsec_1 = offset + xtime_nsec_2
1815	 * Which gives us:
1816	 *	xtime_nsec_2 = xtime_nsec_1 - offset
1817	 * Which simplfies to:
1818	 *	xtime_nsec -= offset
1819	 *
1820	 * XXX - TODO: Doc ntp_error calculation.
1821	 */
1822	if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1823		/* NTP adjustment caused clocksource mult overflow */
1824		WARN_ON_ONCE(1);
1825		return;
1826	}
1827
1828	tk->tkr_mono.mult += mult_adj;
1829	tk->xtime_interval += interval;
1830	tk->tkr_mono.xtime_nsec -= offset;
1831	tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
1832}
1833
1834/*
1835 * Calculate the multiplier adjustment needed to match the frequency
1836 * specified by NTP
1837 */
1838static __always_inline void timekeeping_freqadjust(struct timekeeper *tk,
1839							s64 offset)
1840{
1841	s64 interval = tk->cycle_interval;
1842	s64 xinterval = tk->xtime_interval;
1843	u32 base = tk->tkr_mono.clock->mult;
1844	u32 max = tk->tkr_mono.clock->maxadj;
1845	u32 cur_adj = tk->tkr_mono.mult;
1846	s64 tick_error;
1847	bool negative;
1848	u32 adj_scale;
1849
1850	/* Remove any current error adj from freq calculation */
1851	if (tk->ntp_err_mult)
1852		xinterval -= tk->cycle_interval;
1853
1854	tk->ntp_tick = ntp_tick_length();
1855
1856	/* Calculate current error per tick */
1857	tick_error = ntp_tick_length() >> tk->ntp_error_shift;
1858	tick_error -= (xinterval + tk->xtime_remainder);
1859
1860	/* Don't worry about correcting it if its small */
1861	if (likely((tick_error >= 0) && (tick_error <= interval)))
1862		return;
1863
1864	/* preserve the direction of correction */
1865	negative = (tick_error < 0);
1866
1867	/* If any adjustment would pass the max, just return */
1868	if (negative && (cur_adj - 1) <= (base - max))
1869		return;
1870	if (!negative && (cur_adj + 1) >= (base + max))
1871		return;
1872	/*
1873	 * Sort out the magnitude of the correction, but
1874	 * avoid making so large a correction that we go
1875	 * over the max adjustment.
1876	 */
1877	adj_scale = 0;
1878	tick_error = abs(tick_error);
1879	while (tick_error > interval) {
1880		u32 adj = 1 << (adj_scale + 1);
1881
1882		/* Check if adjustment gets us within 1 unit from the max */
1883		if (negative && (cur_adj - adj) <= (base - max))
1884			break;
1885		if (!negative && (cur_adj + adj) >= (base + max))
1886			break;
1887
1888		adj_scale++;
1889		tick_error >>= 1;
1890	}
1891
1892	/* scale the corrections */
1893	timekeeping_apply_adjustment(tk, offset, negative, adj_scale);
1894}
1895
1896/*
1897 * Adjust the timekeeper's multiplier to the correct frequency
1898 * and also to reduce the accumulated error value.
1899 */
1900static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1901{
1902	/* Correct for the current frequency error */
1903	timekeeping_freqadjust(tk, offset);
1904
1905	/* Next make a small adjustment to fix any cumulative error */
1906	if (!tk->ntp_err_mult && (tk->ntp_error > 0)) {
1907		tk->ntp_err_mult = 1;
1908		timekeeping_apply_adjustment(tk, offset, 0, 0);
1909	} else if (tk->ntp_err_mult && (tk->ntp_error <= 0)) {
1910		/* Undo any existing error adjustment */
1911		timekeeping_apply_adjustment(tk, offset, 1, 0);
1912		tk->ntp_err_mult = 0;
1913	}
1914
1915	if (unlikely(tk->tkr_mono.clock->maxadj &&
1916		(abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
1917			> tk->tkr_mono.clock->maxadj))) {
1918		printk_once(KERN_WARNING
1919			"Adjusting %s more than 11%% (%ld vs %ld)\n",
1920			tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
1921			(long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
1922	}
1923
1924	/*
1925	 * It may be possible that when we entered this function, xtime_nsec
1926	 * was very small.  Further, if we're slightly speeding the clocksource
1927	 * in the code above, its possible the required corrective factor to
1928	 * xtime_nsec could cause it to underflow.
1929	 *
1930	 * Now, since we already accumulated the second, cannot simply roll
1931	 * the accumulated second back, since the NTP subsystem has been
1932	 * notified via second_overflow. So instead we push xtime_nsec forward
1933	 * by the amount we underflowed, and add that amount into the error.
1934	 *
1935	 * We'll correct this error next time through this function, when
1936	 * xtime_nsec is not as small.
1937	 */
1938	if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
1939		s64 neg = -(s64)tk->tkr_mono.xtime_nsec;
1940		tk->tkr_mono.xtime_nsec = 0;
1941		tk->ntp_error += neg << tk->ntp_error_shift;
1942	}
1943}
1944
1945/**
1946 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1947 *
1948 * Helper function that accumulates the nsecs greater than a second
1949 * from the xtime_nsec field to the xtime_secs field.
1950 * It also calls into the NTP code to handle leapsecond processing.
1951 *
1952 */
1953static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1954{
1955	u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
1956	unsigned int clock_set = 0;
1957
1958	while (tk->tkr_mono.xtime_nsec >= nsecps) {
1959		int leap;
1960
1961		tk->tkr_mono.xtime_nsec -= nsecps;
1962		tk->xtime_sec++;
1963
1964		/* Figure out if its a leap sec and apply if needed */
1965		leap = second_overflow(tk->xtime_sec);
1966		if (unlikely(leap)) {
1967			struct timespec64 ts;
1968
1969			tk->xtime_sec += leap;
1970
1971			ts.tv_sec = leap;
1972			ts.tv_nsec = 0;
1973			tk_set_wall_to_mono(tk,
1974				timespec64_sub(tk->wall_to_monotonic, ts));
1975
1976			__timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1977
1978			clock_set = TK_CLOCK_WAS_SET;
1979		}
1980	}
1981	return clock_set;
1982}
1983
1984/**
1985 * logarithmic_accumulation - shifted accumulation of cycles
1986 *
1987 * This functions accumulates a shifted interval of cycles into
1988 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1989 * loop.
1990 *
1991 * Returns the unconsumed cycles.
1992 */
1993static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset,
1994						u32 shift,
1995						unsigned int *clock_set)
1996{
1997	cycle_t interval = tk->cycle_interval << shift;
1998	u64 raw_nsecs;
1999
2000	/* If the offset is smaller than a shifted interval, do nothing */
2001	if (offset < interval)
2002		return offset;
2003
2004	/* Accumulate one shifted interval */
2005	offset -= interval;
2006	tk->tkr_mono.cycle_last += interval;
2007	tk->tkr_raw.cycle_last  += interval;
2008
2009	tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2010	*clock_set |= accumulate_nsecs_to_secs(tk);
 
 
 
 
2011
2012	/* Accumulate raw time */
2013	raw_nsecs = (u64)tk->raw_interval << shift;
2014	raw_nsecs += tk->raw_time.tv_nsec;
2015	if (raw_nsecs >= NSEC_PER_SEC) {
2016		u64 raw_secs = raw_nsecs;
2017		raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
2018		tk->raw_time.tv_sec += raw_secs;
2019	}
2020	tk->raw_time.tv_nsec = raw_nsecs;
2021
2022	/* Accumulate error between NTP and clock interval */
2023	tk->ntp_error += tk->ntp_tick << shift;
2024	tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2025						(tk->ntp_error_shift + shift);
 
2026
2027	return offset;
2028}
2029
 
2030/**
2031 * update_wall_time - Uses the current clocksource to increment the wall time
2032 *
 
2033 */
2034void update_wall_time(void)
2035{
2036	struct timekeeper *real_tk = &tk_core.timekeeper;
2037	struct timekeeper *tk = &shadow_timekeeper;
2038	cycle_t offset;
2039	int shift = 0, maxshift;
2040	unsigned int clock_set = 0;
2041	unsigned long flags;
2042
2043	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2044
2045	/* Make sure we're fully resumed: */
2046	if (unlikely(timekeeping_suspended))
2047		goto out;
 
 
2048
2049#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
2050	offset = real_tk->cycle_interval;
2051#else
2052	offset = clocksource_delta(tk->tkr_mono.read(tk->tkr_mono.clock),
2053				   tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2054#endif
2055
2056	/* Check if there's really nothing to do */
2057	if (offset < real_tk->cycle_interval)
2058		goto out;
2059
2060	/* Do some additional sanity checking */
2061	timekeeping_check_update(real_tk, offset);
2062
2063	/*
2064	 * With NO_HZ we may have to accumulate many cycle_intervals
2065	 * (think "ticks") worth of time at once. To do this efficiently,
2066	 * we calculate the largest doubling multiple of cycle_intervals
2067	 * that is smaller than the offset.  We then accumulate that
2068	 * chunk in one go, and then try to consume the next smaller
2069	 * doubled multiple.
2070	 */
2071	shift = ilog2(offset) - ilog2(tk->cycle_interval);
2072	shift = max(0, shift);
2073	/* Bound shift to one less than what overflows tick_length */
2074	maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2075	shift = min(shift, maxshift);
2076	while (offset >= tk->cycle_interval) {
2077		offset = logarithmic_accumulation(tk, offset, shift,
2078							&clock_set);
2079		if (offset < tk->cycle_interval<<shift)
2080			shift--;
2081	}
2082
2083	/* correct the clock when NTP error is too big */
2084	timekeeping_adjust(tk, offset);
2085
2086	/*
2087	 * XXX This can be killed once everyone converts
2088	 * to the new update_vsyscall.
 
 
 
 
 
 
 
 
 
 
 
 
2089	 */
2090	old_vsyscall_fixup(tk);
 
 
 
 
 
2091
2092	/*
2093	 * Finally, make sure that after the rounding
2094	 * xtime_nsec isn't larger than NSEC_PER_SEC
2095	 */
2096	clock_set |= accumulate_nsecs_to_secs(tk);
 
 
 
2097
2098	write_seqcount_begin(&tk_core.seq);
2099	/*
2100	 * Update the real timekeeper.
2101	 *
2102	 * We could avoid this memcpy by switching pointers, but that
2103	 * requires changes to all other timekeeper usage sites as
2104	 * well, i.e. move the timekeeper pointer getter into the
2105	 * spinlocked/seqcount protected sections. And we trade this
2106	 * memcpy under the tk_core.seq against one before we start
2107	 * updating.
2108	 */
2109	timekeeping_update(tk, clock_set);
2110	memcpy(real_tk, tk, sizeof(*tk));
2111	/* The memcpy must come last. Do not put anything here! */
2112	write_seqcount_end(&tk_core.seq);
2113out:
2114	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2115	if (clock_set)
2116		/* Have to call _delayed version, since in irq context*/
2117		clock_was_set_delayed();
2118}
2119
2120/**
2121 * getboottime64 - Return the real time of system boot.
2122 * @ts:		pointer to the timespec64 to be set
2123 *
2124 * Returns the wall-time of boot in a timespec64.
2125 *
2126 * This is based on the wall_to_monotonic offset and the total suspend
2127 * time. Calls to settimeofday will affect the value returned (which
2128 * basically means that however wrong your real time clock is at boot time,
2129 * you get the right time here).
2130 */
2131void getboottime64(struct timespec64 *ts)
2132{
2133	struct timekeeper *tk = &tk_core.timekeeper;
2134	ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
 
 
2135
2136	*ts = ktime_to_timespec64(t);
2137}
2138EXPORT_SYMBOL_GPL(getboottime64);
2139
2140unsigned long get_seconds(void)
 
 
 
 
 
 
 
 
 
 
2141{
2142	struct timekeeper *tk = &tk_core.timekeeper;
 
 
2143
2144	return tk->xtime_sec;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2145}
2146EXPORT_SYMBOL(get_seconds);
2147
2148struct timespec __current_kernel_time(void)
2149{
2150	struct timekeeper *tk = &tk_core.timekeeper;
2151
2152	return timespec64_to_timespec(tk_xtime(tk));
2153}
2154
2155struct timespec64 current_kernel_time64(void)
2156{
2157	struct timekeeper *tk = &tk_core.timekeeper;
2158	struct timespec64 now;
2159	unsigned long seq;
2160
2161	do {
2162		seq = read_seqcount_begin(&tk_core.seq);
2163
2164		now = tk_xtime(tk);
2165	} while (read_seqcount_retry(&tk_core.seq, seq));
2166
2167	return now;
2168}
2169EXPORT_SYMBOL(current_kernel_time64);
2170
2171struct timespec64 get_monotonic_coarse64(void)
2172{
2173	struct timekeeper *tk = &tk_core.timekeeper;
2174	struct timespec64 now, mono;
2175	unsigned long seq;
2176
2177	do {
2178		seq = read_seqcount_begin(&tk_core.seq);
2179
2180		now = tk_xtime(tk);
2181		mono = tk->wall_to_monotonic;
2182	} while (read_seqcount_retry(&tk_core.seq, seq));
2183
2184	set_normalized_timespec64(&now, now.tv_sec + mono.tv_sec,
2185				now.tv_nsec + mono.tv_nsec);
2186
2187	return now;
2188}
2189
2190/*
2191 * Must hold jiffies_lock
 
 
2192 */
2193void do_timer(unsigned long ticks)
2194{
2195	jiffies_64 += ticks;
 
2196	calc_global_load(ticks);
2197}
2198
2199/**
2200 * ktime_get_update_offsets_now - hrtimer helper
2201 * @cwsseq:	pointer to check and store the clock was set sequence number
2202 * @offs_real:	pointer to storage for monotonic -> realtime offset
2203 * @offs_boot:	pointer to storage for monotonic -> boottime offset
2204 * @offs_tai:	pointer to storage for monotonic -> clock tai offset
2205 *
2206 * Returns current monotonic time and updates the offsets if the
2207 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2208 * different.
2209 *
2210 * Called from hrtimer_interrupt() or retrigger_next_event()
2211 */
2212ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2213				     ktime_t *offs_boot, ktime_t *offs_tai)
2214{
2215	struct timekeeper *tk = &tk_core.timekeeper;
2216	unsigned int seq;
2217	ktime_t base;
2218	u64 nsecs;
2219
2220	do {
2221		seq = read_seqcount_begin(&tk_core.seq);
2222
2223		base = tk->tkr_mono.base;
2224		nsecs = timekeeping_get_ns(&tk->tkr_mono);
2225		base = ktime_add_ns(base, nsecs);
2226
2227		if (*cwsseq != tk->clock_was_set_seq) {
2228			*cwsseq = tk->clock_was_set_seq;
2229			*offs_real = tk->offs_real;
2230			*offs_boot = tk->offs_boot;
2231			*offs_tai = tk->offs_tai;
2232		}
2233
2234		/* Handle leapsecond insertion adjustments */
2235		if (unlikely(base.tv64 >= tk->next_leap_ktime.tv64))
2236			*offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2237
2238	} while (read_seqcount_retry(&tk_core.seq, seq));
2239
2240	return base;
2241}
2242
2243/**
2244 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2245 */
2246int do_adjtimex(struct timex *txc)
2247{
2248	struct timekeeper *tk = &tk_core.timekeeper;
2249	unsigned long flags;
2250	struct timespec64 ts;
2251	s32 orig_tai, tai;
2252	int ret;
2253
2254	/* Validate the data before disabling interrupts */
2255	ret = ntp_validate_timex(txc);
2256	if (ret)
2257		return ret;
2258
2259	if (txc->modes & ADJ_SETOFFSET) {
2260		struct timespec delta;
2261		delta.tv_sec  = txc->time.tv_sec;
2262		delta.tv_nsec = txc->time.tv_usec;
2263		if (!(txc->modes & ADJ_NANO))
2264			delta.tv_nsec *= 1000;
2265		ret = timekeeping_inject_offset(&delta);
2266		if (ret)
2267			return ret;
2268	}
2269
2270	getnstimeofday64(&ts);
2271
2272	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2273	write_seqcount_begin(&tk_core.seq);
2274
2275	orig_tai = tai = tk->tai_offset;
2276	ret = __do_adjtimex(txc, &ts, &tai);
2277
2278	if (tai != orig_tai) {
2279		__timekeeping_set_tai_offset(tk, tai);
2280		timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2281	}
2282	tk_update_leap_state(tk);
2283
2284	write_seqcount_end(&tk_core.seq);
2285	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2286
2287	if (tai != orig_tai)
2288		clock_was_set();
2289
2290	ntp_notify_cmos_timer();
2291
2292	return ret;
2293}
2294
2295#ifdef CONFIG_NTP_PPS
2296/**
2297 * hardpps() - Accessor function to NTP __hardpps function
2298 */
2299void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2300{
2301	unsigned long flags;
2302
2303	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2304	write_seqcount_begin(&tk_core.seq);
2305
2306	__hardpps(phase_ts, raw_ts);
2307
2308	write_seqcount_end(&tk_core.seq);
2309	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 
 
 
2310}
2311EXPORT_SYMBOL(hardpps);
2312#endif
2313
2314/**
2315 * xtime_update() - advances the timekeeping infrastructure
2316 * @ticks:	number of ticks, that have elapsed since the last call.
2317 *
2318 * Must be called with interrupts disabled.
2319 */
2320void xtime_update(unsigned long ticks)
2321{
2322	write_seqlock(&jiffies_lock);
2323	do_timer(ticks);
2324	write_sequnlock(&jiffies_lock);
2325	update_wall_time();
2326}