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 != timespec64_to_ktime(tmp));
 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, u64 offset)
 123{
 124
 125	u64 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 u64 timekeeping_get_delta(struct tk_read_base *tkr)
 162{
 163	struct timekeeper *tk = &tk_core.timekeeper;
 164	u64 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, u64 offset)
 203{
 204}
 205static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
 206{
 207	u64 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	u64 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 = (u64) tmp;
 258	tk->cycle_interval = interval;
 259
 260	/* Go back from cycles -> shifted ns */
 261	tk->xtime_interval = interval * clock->mult;
 262	tk->xtime_remainder = ntpinterval - tk->xtime_interval;
 263	tk->raw_interval = (interval * clock->mult) >> clock->shift;
 264
 265	 /* if changing clocks, convert xtime_nsec shift units */
 266	if (old_clock) {
 267		int shift_change = clock->shift - old_clock->shift;
 268		if (shift_change < 0)
 269			tk->tkr_mono.xtime_nsec >>= -shift_change;
 270		else
 
 271			tk->tkr_mono.xtime_nsec <<= shift_change;
 
 
 272	}
 273	tk->tkr_raw.xtime_nsec = 0;
 274
 275	tk->tkr_mono.shift = clock->shift;
 276	tk->tkr_raw.shift = clock->shift;
 277
 278	tk->ntp_error = 0;
 279	tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
 280	tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
 281
 282	/*
 283	 * The timekeeper keeps its own mult values for the currently
 284	 * active clocksource. These value will be adjusted via NTP
 285	 * to counteract clock drifting.
 286	 */
 287	tk->tkr_mono.mult = clock->mult;
 288	tk->tkr_raw.mult = clock->mult;
 289	tk->ntp_err_mult = 0;
 
 290}
 291
 292/* Timekeeper helper functions. */
 293
 294#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
 295static u32 default_arch_gettimeoffset(void) { return 0; }
 296u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
 297#else
 298static inline u32 arch_gettimeoffset(void) { return 0; }
 299#endif
 300
 301static inline u64 timekeeping_delta_to_ns(struct tk_read_base *tkr, u64 delta)
 302{
 303	u64 nsec;
 304
 305	nsec = delta * tkr->mult + tkr->xtime_nsec;
 306	nsec >>= tkr->shift;
 307
 308	/* If arch requires, add in get_arch_timeoffset() */
 309	return nsec + arch_gettimeoffset();
 310}
 311
 312static inline u64 timekeeping_get_ns(struct tk_read_base *tkr)
 313{
 314	u64 delta;
 315
 316	delta = timekeeping_get_delta(tkr);
 317	return timekeeping_delta_to_ns(tkr, delta);
 318}
 319
 320static inline u64 timekeeping_cycles_to_ns(struct tk_read_base *tkr, u64 cycles)
 321{
 322	u64 delta;
 323
 324	/* calculate the delta since the last update_wall_time */
 325	delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
 326	return timekeeping_delta_to_ns(tkr, delta);
 327}
 328
 329/**
 330 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
 331 * @tkr: Timekeeping readout base from which we take the update
 332 *
 333 * We want to use this from any context including NMI and tracing /
 334 * instrumenting the timekeeping code itself.
 335 *
 336 * Employ the latch technique; see @raw_write_seqcount_latch.
 337 *
 338 * So if a NMI hits the update of base[0] then it will use base[1]
 339 * which is still consistent. In the worst case this can result is a
 340 * slightly wrong timestamp (a few nanoseconds). See
 341 * @ktime_get_mono_fast_ns.
 342 */
 343static void update_fast_timekeeper(struct tk_read_base *tkr, struct tk_fast *tkf)
 
 344{
 345	struct tk_read_base *base = tkf->base;
 346
 347	/* Force readers off to base[1] */
 348	raw_write_seqcount_latch(&tkf->seq);
 349
 350	/* Update base[0] */
 351	memcpy(base, tkr, sizeof(*base));
 352
 353	/* Force readers back to base[0] */
 354	raw_write_seqcount_latch(&tkf->seq);
 355
 356	/* Update base[1] */
 357	memcpy(base + 1, base, sizeof(*base));
 358}
 359
 360/**
 361 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
 362 *
 363 * This timestamp is not guaranteed to be monotonic across an update.
 364 * The timestamp is calculated by:
 365 *
 366 *	now = base_mono + clock_delta * slope
 367 *
 368 * So if the update lowers the slope, readers who are forced to the
 369 * not yet updated second array are still using the old steeper slope.
 370 *
 371 * tmono
 372 * ^
 373 * |    o  n
 374 * |   o n
 375 * |  u
 376 * | o
 377 * |o
 378 * |12345678---> reader order
 379 *
 380 * o = old slope
 381 * u = update
 382 * n = new slope
 383 *
 384 * So reader 6 will observe time going backwards versus reader 5.
 385 *
 386 * While other CPUs are likely to be able observe that, the only way
 387 * for a CPU local observation is when an NMI hits in the middle of
 388 * the update. Timestamps taken from that NMI context might be ahead
 389 * of the following timestamps. Callers need to be aware of that and
 390 * deal with it.
 391 */
 392static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
 393{
 394	struct tk_read_base *tkr;
 395	unsigned int seq;
 396	u64 now;
 397
 398	do {
 399		seq = raw_read_seqcount_latch(&tkf->seq);
 400		tkr = tkf->base + (seq & 0x01);
 401		now = ktime_to_ns(tkr->base);
 402
 403		now += timekeeping_delta_to_ns(tkr,
 404				clocksource_delta(
 405					tkr->read(tkr->clock),
 406					tkr->cycle_last,
 407					tkr->mask));
 408	} while (read_seqcount_retry(&tkf->seq, seq));
 409
 410	return now;
 411}
 412
 413u64 ktime_get_mono_fast_ns(void)
 414{
 415	return __ktime_get_fast_ns(&tk_fast_mono);
 416}
 417EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
 418
 419u64 ktime_get_raw_fast_ns(void)
 420{
 421	return __ktime_get_fast_ns(&tk_fast_raw);
 422}
 423EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
 424
 425/**
 426 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
 427 *
 428 * To keep it NMI safe since we're accessing from tracing, we're not using a
 429 * separate timekeeper with updates to monotonic clock and boot offset
 430 * protected with seqlocks. This has the following minor side effects:
 431 *
 432 * (1) Its possible that a timestamp be taken after the boot offset is updated
 433 * but before the timekeeper is updated. If this happens, the new boot offset
 434 * is added to the old timekeeping making the clock appear to update slightly
 435 * earlier:
 436 *    CPU 0                                        CPU 1
 437 *    timekeeping_inject_sleeptime64()
 438 *    __timekeeping_inject_sleeptime(tk, delta);
 439 *                                                 timestamp();
 440 *    timekeeping_update(tk, TK_CLEAR_NTP...);
 441 *
 442 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
 443 * partially updated.  Since the tk->offs_boot update is a rare event, this
 444 * should be a rare occurrence which postprocessing should be able to handle.
 445 */
 446u64 notrace ktime_get_boot_fast_ns(void)
 447{
 448	struct timekeeper *tk = &tk_core.timekeeper;
 449
 450	return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
 451}
 452EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
 453
 454/* Suspend-time cycles value for halted fast timekeeper. */
 455static u64 cycles_at_suspend;
 456
 457static u64 dummy_clock_read(struct clocksource *cs)
 
 
 
 458{
 459	return cycles_at_suspend;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 460}
 461
 462/**
 
 
 
 
 
 
 
 
 
 463 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
 464 * @tk: Timekeeper to snapshot.
 465 *
 466 * It generally is unsafe to access the clocksource after timekeeping has been
 467 * suspended, so take a snapshot of the readout base of @tk and use it as the
 468 * fast timekeeper's readout base while suspended.  It will return the same
 469 * number of cycles every time until timekeeping is resumed at which time the
 470 * proper readout base for the fast timekeeper will be restored automatically.
 471 */
 472static void halt_fast_timekeeper(struct timekeeper *tk)
 473{
 474	static struct tk_read_base tkr_dummy;
 475	struct tk_read_base *tkr = &tk->tkr_mono;
 476
 477	memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
 478	cycles_at_suspend = tkr->read(tkr->clock);
 479	tkr_dummy.read = dummy_clock_read;
 
 480	update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
 481
 482	tkr = &tk->tkr_raw;
 483	memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
 484	tkr_dummy.read = dummy_clock_read;
 485	update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
 486}
 487
 488#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
 489
 490static inline void update_vsyscall(struct timekeeper *tk)
 491{
 492	struct timespec xt, wm;
 493
 494	xt = timespec64_to_timespec(tk_xtime(tk));
 495	wm = timespec64_to_timespec(tk->wall_to_monotonic);
 496	update_vsyscall_old(&xt, &wm, tk->tkr_mono.clock, tk->tkr_mono.mult,
 497			    tk->tkr_mono.cycle_last);
 498}
 499
 500static inline void old_vsyscall_fixup(struct timekeeper *tk)
 501{
 502	s64 remainder;
 503
 504	/*
 505	* Store only full nanoseconds into xtime_nsec after rounding
 506	* it up and add the remainder to the error difference.
 507	* XXX - This is necessary to avoid small 1ns inconsistnecies caused
 508	* by truncating the remainder in vsyscalls. However, it causes
 509	* additional work to be done in timekeeping_adjust(). Once
 510	* the vsyscall implementations are converted to use xtime_nsec
 511	* (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
 512	* users are removed, this can be killed.
 513	*/
 514	remainder = tk->tkr_mono.xtime_nsec & ((1ULL << tk->tkr_mono.shift) - 1);
 515	if (remainder != 0) {
 516		tk->tkr_mono.xtime_nsec -= remainder;
 517		tk->tkr_mono.xtime_nsec += 1ULL << tk->tkr_mono.shift;
 518		tk->ntp_error += remainder << tk->ntp_error_shift;
 519		tk->ntp_error -= (1ULL << tk->tkr_mono.shift) << tk->ntp_error_shift;
 520	}
 521}
 522#else
 523#define old_vsyscall_fixup(tk)
 524#endif
 525
 526static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
 527
 528static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
 529{
 530	raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
 531}
 532
 533/**
 534 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
 535 */
 536int pvclock_gtod_register_notifier(struct notifier_block *nb)
 537{
 538	struct timekeeper *tk = &tk_core.timekeeper;
 539	unsigned long flags;
 540	int ret;
 541
 542	raw_spin_lock_irqsave(&timekeeper_lock, flags);
 543	ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
 544	update_pvclock_gtod(tk, true);
 545	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 546
 547	return ret;
 548}
 549EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
 550
 551/**
 552 * pvclock_gtod_unregister_notifier - unregister a pvclock
 553 * timedata update listener
 554 */
 555int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
 556{
 557	unsigned long flags;
 558	int ret;
 559
 560	raw_spin_lock_irqsave(&timekeeper_lock, flags);
 561	ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
 562	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 563
 564	return ret;
 565}
 566EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
 567
 568/*
 569 * tk_update_leap_state - helper to update the next_leap_ktime
 570 */
 571static inline void tk_update_leap_state(struct timekeeper *tk)
 572{
 573	tk->next_leap_ktime = ntp_get_next_leap();
 574	if (tk->next_leap_ktime != KTIME_MAX)
 575		/* Convert to monotonic time */
 576		tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
 577}
 578
 579/*
 580 * Update the ktime_t based scalar nsec members of the timekeeper
 581 */
 582static inline void tk_update_ktime_data(struct timekeeper *tk)
 583{
 584	u64 seconds;
 585	u32 nsec;
 586
 587	/*
 588	 * The xtime based monotonic readout is:
 589	 *	nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
 590	 * The ktime based monotonic readout is:
 591	 *	nsec = base_mono + now();
 592	 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
 593	 */
 594	seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
 595	nsec = (u32) tk->wall_to_monotonic.tv_nsec;
 596	tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
 597
 598	/* Update the monotonic raw base */
 599	tk->tkr_raw.base = timespec64_to_ktime(tk->raw_time);
 600
 601	/*
 602	 * The sum of the nanoseconds portions of xtime and
 603	 * wall_to_monotonic can be greater/equal one second. Take
 604	 * this into account before updating tk->ktime_sec.
 605	 */
 606	nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
 607	if (nsec >= NSEC_PER_SEC)
 608		seconds++;
 609	tk->ktime_sec = seconds;
 
 
 
 610}
 611
 612/* must hold timekeeper_lock */
 613static void timekeeping_update(struct timekeeper *tk, unsigned int action)
 614{
 615	if (action & TK_CLEAR_NTP) {
 616		tk->ntp_error = 0;
 617		ntp_clear();
 618	}
 619
 620	tk_update_leap_state(tk);
 621	tk_update_ktime_data(tk);
 622
 623	update_vsyscall(tk);
 624	update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
 625
 
 626	update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
 627	update_fast_timekeeper(&tk->tkr_raw,  &tk_fast_raw);
 628
 629	if (action & TK_CLOCK_WAS_SET)
 630		tk->clock_was_set_seq++;
 631	/*
 632	 * The mirroring of the data to the shadow-timekeeper needs
 633	 * to happen last here to ensure we don't over-write the
 634	 * timekeeper structure on the next update with stale data
 635	 */
 636	if (action & TK_MIRROR)
 637		memcpy(&shadow_timekeeper, &tk_core.timekeeper,
 638		       sizeof(tk_core.timekeeper));
 639}
 640
 641/**
 642 * timekeeping_forward_now - update clock to the current time
 643 *
 644 * Forward the current clock to update its state since the last call to
 645 * update_wall_time(). This is useful before significant clock changes,
 646 * as it avoids having to deal with this time offset explicitly.
 647 */
 648static void timekeeping_forward_now(struct timekeeper *tk)
 649{
 650	struct clocksource *clock = tk->tkr_mono.clock;
 651	u64 cycle_now, delta;
 652	u64 nsec;
 653
 654	cycle_now = tk->tkr_mono.read(clock);
 655	delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
 656	tk->tkr_mono.cycle_last = cycle_now;
 657	tk->tkr_raw.cycle_last  = cycle_now;
 658
 659	tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
 660
 661	/* If arch requires, add in get_arch_timeoffset() */
 662	tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
 663
 664	tk_normalize_xtime(tk);
 665
 666	nsec = clocksource_cyc2ns(delta, tk->tkr_raw.mult, tk->tkr_raw.shift);
 667	timespec64_add_ns(&tk->raw_time, nsec);
 
 
 
 
 668}
 669
 670/**
 671 * __getnstimeofday64 - Returns the time of day in a timespec64.
 672 * @ts:		pointer to the timespec to be set
 673 *
 674 * Updates the time of day in the timespec.
 675 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
 676 */
 677int __getnstimeofday64(struct timespec64 *ts)
 678{
 679	struct timekeeper *tk = &tk_core.timekeeper;
 680	unsigned long seq;
 681	u64 nsecs;
 682
 
 
 683	do {
 684		seq = read_seqcount_begin(&tk_core.seq);
 685
 686		ts->tv_sec = tk->xtime_sec;
 687		nsecs = timekeeping_get_ns(&tk->tkr_mono);
 688
 689	} while (read_seqcount_retry(&tk_core.seq, seq));
 690
 691	ts->tv_nsec = 0;
 692	timespec64_add_ns(ts, nsecs);
 693
 694	/*
 695	 * Do not bail out early, in case there were callers still using
 696	 * the value, even in the face of the WARN_ON.
 697	 */
 698	if (unlikely(timekeeping_suspended))
 699		return -EAGAIN;
 700	return 0;
 701}
 702EXPORT_SYMBOL(__getnstimeofday64);
 703
 704/**
 705 * getnstimeofday64 - Returns the time of day in a timespec64.
 706 * @ts:		pointer to the timespec64 to be set
 707 *
 708 * Returns the time of day in a timespec64 (WARN if suspended).
 709 */
 710void getnstimeofday64(struct timespec64 *ts)
 711{
 712	WARN_ON(__getnstimeofday64(ts));
 713}
 714EXPORT_SYMBOL(getnstimeofday64);
 715
 716ktime_t ktime_get(void)
 717{
 718	struct timekeeper *tk = &tk_core.timekeeper;
 719	unsigned int seq;
 720	ktime_t base;
 721	u64 nsecs;
 722
 723	WARN_ON(timekeeping_suspended);
 724
 725	do {
 726		seq = read_seqcount_begin(&tk_core.seq);
 727		base = tk->tkr_mono.base;
 728		nsecs = timekeeping_get_ns(&tk->tkr_mono);
 729
 730	} while (read_seqcount_retry(&tk_core.seq, seq));
 731
 732	return ktime_add_ns(base, nsecs);
 733}
 734EXPORT_SYMBOL_GPL(ktime_get);
 735
 736u32 ktime_get_resolution_ns(void)
 737{
 738	struct timekeeper *tk = &tk_core.timekeeper;
 739	unsigned int seq;
 740	u32 nsecs;
 741
 742	WARN_ON(timekeeping_suspended);
 743
 744	do {
 745		seq = read_seqcount_begin(&tk_core.seq);
 746		nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
 747	} while (read_seqcount_retry(&tk_core.seq, seq));
 748
 749	return nsecs;
 750}
 751EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
 752
 753static ktime_t *offsets[TK_OFFS_MAX] = {
 754	[TK_OFFS_REAL]	= &tk_core.timekeeper.offs_real,
 755	[TK_OFFS_BOOT]	= &tk_core.timekeeper.offs_boot,
 756	[TK_OFFS_TAI]	= &tk_core.timekeeper.offs_tai,
 757};
 758
 759ktime_t ktime_get_with_offset(enum tk_offsets offs)
 760{
 761	struct timekeeper *tk = &tk_core.timekeeper;
 762	unsigned int seq;
 763	ktime_t base, *offset = offsets[offs];
 764	u64 nsecs;
 765
 766	WARN_ON(timekeeping_suspended);
 767
 768	do {
 769		seq = read_seqcount_begin(&tk_core.seq);
 770		base = ktime_add(tk->tkr_mono.base, *offset);
 771		nsecs = timekeeping_get_ns(&tk->tkr_mono);
 772
 773	} while (read_seqcount_retry(&tk_core.seq, seq));
 774
 775	return ktime_add_ns(base, nsecs);
 776
 777}
 778EXPORT_SYMBOL_GPL(ktime_get_with_offset);
 779
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 780/**
 781 * ktime_mono_to_any() - convert mononotic time to any other time
 782 * @tmono:	time to convert.
 783 * @offs:	which offset to use
 784 */
 785ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
 786{
 787	ktime_t *offset = offsets[offs];
 788	unsigned long seq;
 789	ktime_t tconv;
 790
 791	do {
 792		seq = read_seqcount_begin(&tk_core.seq);
 793		tconv = ktime_add(tmono, *offset);
 794	} while (read_seqcount_retry(&tk_core.seq, seq));
 795
 796	return tconv;
 797}
 798EXPORT_SYMBOL_GPL(ktime_mono_to_any);
 799
 800/**
 801 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
 802 */
 803ktime_t ktime_get_raw(void)
 804{
 805	struct timekeeper *tk = &tk_core.timekeeper;
 806	unsigned int seq;
 807	ktime_t base;
 808	u64 nsecs;
 809
 810	do {
 811		seq = read_seqcount_begin(&tk_core.seq);
 812		base = tk->tkr_raw.base;
 813		nsecs = timekeeping_get_ns(&tk->tkr_raw);
 814
 815	} while (read_seqcount_retry(&tk_core.seq, seq));
 816
 817	return ktime_add_ns(base, nsecs);
 818}
 819EXPORT_SYMBOL_GPL(ktime_get_raw);
 820
 821/**
 822 * ktime_get_ts64 - get the monotonic clock in timespec64 format
 823 * @ts:		pointer to timespec variable
 824 *
 825 * The function calculates the monotonic clock from the realtime
 826 * clock and the wall_to_monotonic offset and stores the result
 827 * in normalized timespec64 format in the variable pointed to by @ts.
 828 */
 829void ktime_get_ts64(struct timespec64 *ts)
 830{
 831	struct timekeeper *tk = &tk_core.timekeeper;
 832	struct timespec64 tomono;
 833	unsigned int seq;
 834	u64 nsec;
 835
 836	WARN_ON(timekeeping_suspended);
 837
 838	do {
 839		seq = read_seqcount_begin(&tk_core.seq);
 840		ts->tv_sec = tk->xtime_sec;
 841		nsec = timekeeping_get_ns(&tk->tkr_mono);
 842		tomono = tk->wall_to_monotonic;
 843
 844	} while (read_seqcount_retry(&tk_core.seq, seq));
 845
 846	ts->tv_sec += tomono.tv_sec;
 847	ts->tv_nsec = 0;
 848	timespec64_add_ns(ts, nsec + tomono.tv_nsec);
 849}
 850EXPORT_SYMBOL_GPL(ktime_get_ts64);
 851
 852/**
 853 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
 854 *
 855 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
 856 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
 857 * works on both 32 and 64 bit systems. On 32 bit systems the readout
 858 * covers ~136 years of uptime which should be enough to prevent
 859 * premature wrap arounds.
 860 */
 861time64_t ktime_get_seconds(void)
 862{
 863	struct timekeeper *tk = &tk_core.timekeeper;
 864
 865	WARN_ON(timekeeping_suspended);
 866	return tk->ktime_sec;
 867}
 868EXPORT_SYMBOL_GPL(ktime_get_seconds);
 869
 870/**
 871 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
 872 *
 873 * Returns the wall clock seconds since 1970. This replaces the
 874 * get_seconds() interface which is not y2038 safe on 32bit systems.
 875 *
 876 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
 877 * 32bit systems the access must be protected with the sequence
 878 * counter to provide "atomic" access to the 64bit tk->xtime_sec
 879 * value.
 880 */
 881time64_t ktime_get_real_seconds(void)
 882{
 883	struct timekeeper *tk = &tk_core.timekeeper;
 884	time64_t seconds;
 885	unsigned int seq;
 886
 887	if (IS_ENABLED(CONFIG_64BIT))
 888		return tk->xtime_sec;
 889
 890	do {
 891		seq = read_seqcount_begin(&tk_core.seq);
 892		seconds = tk->xtime_sec;
 893
 894	} while (read_seqcount_retry(&tk_core.seq, seq));
 895
 896	return seconds;
 897}
 898EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
 899
 900/**
 901 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
 902 * but without the sequence counter protect. This internal function
 903 * is called just when timekeeping lock is already held.
 904 */
 905time64_t __ktime_get_real_seconds(void)
 906{
 907	struct timekeeper *tk = &tk_core.timekeeper;
 908
 909	return tk->xtime_sec;
 910}
 911
 912/**
 913 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
 914 * @systime_snapshot:	pointer to struct receiving the system time snapshot
 915 */
 916void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 917{
 918	struct timekeeper *tk = &tk_core.timekeeper;
 919	unsigned long seq;
 920	ktime_t base_raw;
 921	ktime_t base_real;
 922	u64 nsec_raw;
 923	u64 nsec_real;
 924	u64 now;
 925
 926	WARN_ON_ONCE(timekeeping_suspended);
 927
 928	do {
 929		seq = read_seqcount_begin(&tk_core.seq);
 930
 931		now = tk->tkr_mono.read(tk->tkr_mono.clock);
 932		systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
 933		systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
 934		base_real = ktime_add(tk->tkr_mono.base,
 935				      tk_core.timekeeper.offs_real);
 936		base_raw = tk->tkr_raw.base;
 937		nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
 938		nsec_raw  = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
 939	} while (read_seqcount_retry(&tk_core.seq, seq));
 940
 941	systime_snapshot->cycles = now;
 942	systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
 943	systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
 944}
 945EXPORT_SYMBOL_GPL(ktime_get_snapshot);
 946
 947/* Scale base by mult/div checking for overflow */
 948static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
 949{
 950	u64 tmp, rem;
 951
 952	tmp = div64_u64_rem(*base, div, &rem);
 953
 954	if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
 955	    ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
 956		return -EOVERFLOW;
 957	tmp *= mult;
 958	rem *= mult;
 959
 960	do_div(rem, div);
 961	*base = tmp + rem;
 962	return 0;
 963}
 964
 965/**
 966 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
 967 * @history:			Snapshot representing start of history
 968 * @partial_history_cycles:	Cycle offset into history (fractional part)
 969 * @total_history_cycles:	Total history length in cycles
 970 * @discontinuity:		True indicates clock was set on history period
 971 * @ts:				Cross timestamp that should be adjusted using
 972 *	partial/total ratio
 973 *
 974 * Helper function used by get_device_system_crosststamp() to correct the
 975 * crosstimestamp corresponding to the start of the current interval to the
 976 * system counter value (timestamp point) provided by the driver. The
 977 * total_history_* quantities are the total history starting at the provided
 978 * reference point and ending at the start of the current interval. The cycle
 979 * count between the driver timestamp point and the start of the current
 980 * interval is partial_history_cycles.
 981 */
 982static int adjust_historical_crosststamp(struct system_time_snapshot *history,
 983					 u64 partial_history_cycles,
 984					 u64 total_history_cycles,
 985					 bool discontinuity,
 986					 struct system_device_crosststamp *ts)
 987{
 988	struct timekeeper *tk = &tk_core.timekeeper;
 989	u64 corr_raw, corr_real;
 990	bool interp_forward;
 991	int ret;
 992
 993	if (total_history_cycles == 0 || partial_history_cycles == 0)
 994		return 0;
 995
 996	/* Interpolate shortest distance from beginning or end of history */
 997	interp_forward = partial_history_cycles > total_history_cycles/2 ?
 998		true : false;
 999	partial_history_cycles = interp_forward ?
1000		total_history_cycles - partial_history_cycles :
1001		partial_history_cycles;
1002
1003	/*
1004	 * Scale the monotonic raw time delta by:
1005	 *	partial_history_cycles / total_history_cycles
1006	 */
1007	corr_raw = (u64)ktime_to_ns(
1008		ktime_sub(ts->sys_monoraw, history->raw));
1009	ret = scale64_check_overflow(partial_history_cycles,
1010				     total_history_cycles, &corr_raw);
1011	if (ret)
1012		return ret;
1013
1014	/*
1015	 * If there is a discontinuity in the history, scale monotonic raw
1016	 *	correction by:
1017	 *	mult(real)/mult(raw) yielding the realtime correction
1018	 * Otherwise, calculate the realtime correction similar to monotonic
1019	 *	raw calculation
1020	 */
1021	if (discontinuity) {
1022		corr_real = mul_u64_u32_div
1023			(corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1024	} else {
1025		corr_real = (u64)ktime_to_ns(
1026			ktime_sub(ts->sys_realtime, history->real));
1027		ret = scale64_check_overflow(partial_history_cycles,
1028					     total_history_cycles, &corr_real);
1029		if (ret)
1030			return ret;
1031	}
1032
1033	/* Fixup monotonic raw and real time time values */
1034	if (interp_forward) {
1035		ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1036		ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1037	} else {
1038		ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1039		ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1040	}
1041
1042	return 0;
1043}
1044
1045/*
1046 * cycle_between - true if test occurs chronologically between before and after
1047 */
1048static bool cycle_between(u64 before, u64 test, u64 after)
1049{
1050	if (test > before && test < after)
1051		return true;
1052	if (test < before && before > after)
1053		return true;
1054	return false;
1055}
1056
1057/**
1058 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1059 * @get_time_fn:	Callback to get simultaneous device time and
1060 *	system counter from the device driver
1061 * @ctx:		Context passed to get_time_fn()
1062 * @history_begin:	Historical reference point used to interpolate system
1063 *	time when counter provided by the driver is before the current interval
1064 * @xtstamp:		Receives simultaneously captured system and device time
1065 *
1066 * Reads a timestamp from a device and correlates it to system time
1067 */
1068int get_device_system_crosststamp(int (*get_time_fn)
1069				  (ktime_t *device_time,
1070				   struct system_counterval_t *sys_counterval,
1071				   void *ctx),
1072				  void *ctx,
1073				  struct system_time_snapshot *history_begin,
1074				  struct system_device_crosststamp *xtstamp)
1075{
1076	struct system_counterval_t system_counterval;
1077	struct timekeeper *tk = &tk_core.timekeeper;
1078	u64 cycles, now, interval_start;
1079	unsigned int clock_was_set_seq = 0;
1080	ktime_t base_real, base_raw;
1081	u64 nsec_real, nsec_raw;
1082	u8 cs_was_changed_seq;
1083	unsigned long seq;
1084	bool do_interp;
1085	int ret;
1086
1087	do {
1088		seq = read_seqcount_begin(&tk_core.seq);
1089		/*
1090		 * Try to synchronously capture device time and a system
1091		 * counter value calling back into the device driver
1092		 */
1093		ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1094		if (ret)
1095			return ret;
1096
1097		/*
1098		 * Verify that the clocksource associated with the captured
1099		 * system counter value is the same as the currently installed
1100		 * timekeeper clocksource
1101		 */
1102		if (tk->tkr_mono.clock != system_counterval.cs)
1103			return -ENODEV;
1104		cycles = system_counterval.cycles;
1105
1106		/*
1107		 * Check whether the system counter value provided by the
1108		 * device driver is on the current timekeeping interval.
1109		 */
1110		now = tk->tkr_mono.read(tk->tkr_mono.clock);
1111		interval_start = tk->tkr_mono.cycle_last;
1112		if (!cycle_between(interval_start, cycles, now)) {
1113			clock_was_set_seq = tk->clock_was_set_seq;
1114			cs_was_changed_seq = tk->cs_was_changed_seq;
1115			cycles = interval_start;
1116			do_interp = true;
1117		} else {
1118			do_interp = false;
1119		}
1120
1121		base_real = ktime_add(tk->tkr_mono.base,
1122				      tk_core.timekeeper.offs_real);
1123		base_raw = tk->tkr_raw.base;
1124
1125		nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1126						     system_counterval.cycles);
1127		nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1128						    system_counterval.cycles);
1129	} while (read_seqcount_retry(&tk_core.seq, seq));
1130
1131	xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1132	xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1133
1134	/*
1135	 * Interpolate if necessary, adjusting back from the start of the
1136	 * current interval
1137	 */
1138	if (do_interp) {
1139		u64 partial_history_cycles, total_history_cycles;
1140		bool discontinuity;
1141
1142		/*
1143		 * Check that the counter value occurs after the provided
1144		 * history reference and that the history doesn't cross a
1145		 * clocksource change
1146		 */
1147		if (!history_begin ||
1148		    !cycle_between(history_begin->cycles,
1149				   system_counterval.cycles, cycles) ||
1150		    history_begin->cs_was_changed_seq != cs_was_changed_seq)
1151			return -EINVAL;
1152		partial_history_cycles = cycles - system_counterval.cycles;
1153		total_history_cycles = cycles - history_begin->cycles;
1154		discontinuity =
1155			history_begin->clock_was_set_seq != clock_was_set_seq;
1156
1157		ret = adjust_historical_crosststamp(history_begin,
1158						    partial_history_cycles,
1159						    total_history_cycles,
1160						    discontinuity, xtstamp);
1161		if (ret)
1162			return ret;
1163	}
1164
1165	return 0;
1166}
1167EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1168
1169/**
1170 * do_gettimeofday - Returns the time of day in a timeval
1171 * @tv:		pointer to the timeval to be set
1172 *
1173 * NOTE: Users should be converted to using getnstimeofday()
1174 */
1175void do_gettimeofday(struct timeval *tv)
1176{
1177	struct timespec64 now;
1178
1179	getnstimeofday64(&now);
1180	tv->tv_sec = now.tv_sec;
1181	tv->tv_usec = now.tv_nsec/1000;
1182}
1183EXPORT_SYMBOL(do_gettimeofday);
1184
1185/**
1186 * do_settimeofday64 - Sets the time of day.
1187 * @ts:     pointer to the timespec64 variable containing the new time
1188 *
1189 * Sets the time of day to the new time and update NTP and notify hrtimers
1190 */
1191int do_settimeofday64(const struct timespec64 *ts)
1192{
1193	struct timekeeper *tk = &tk_core.timekeeper;
1194	struct timespec64 ts_delta, xt;
1195	unsigned long flags;
1196	int ret = 0;
1197
1198	if (!timespec64_valid_strict(ts))
1199		return -EINVAL;
1200
1201	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1202	write_seqcount_begin(&tk_core.seq);
1203
1204	timekeeping_forward_now(tk);
1205
1206	xt = tk_xtime(tk);
1207	ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1208	ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1209
1210	if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1211		ret = -EINVAL;
1212		goto out;
1213	}
1214
1215	tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1216
1217	tk_set_xtime(tk, ts);
1218out:
1219	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1220
1221	write_seqcount_end(&tk_core.seq);
1222	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1223
1224	/* signal hrtimers about time change */
1225	clock_was_set();
1226
 
 
 
1227	return ret;
1228}
1229EXPORT_SYMBOL(do_settimeofday64);
1230
1231/**
1232 * timekeeping_inject_offset - Adds or subtracts from the current time.
1233 * @tv:		pointer to the timespec variable containing the offset
1234 *
1235 * Adds or subtracts an offset value from the current time.
1236 */
1237int timekeeping_inject_offset(struct timespec *ts)
1238{
1239	struct timekeeper *tk = &tk_core.timekeeper;
1240	unsigned long flags;
1241	struct timespec64 ts64, tmp;
1242	int ret = 0;
1243
1244	if (!timespec_inject_offset_valid(ts))
1245		return -EINVAL;
1246
1247	ts64 = timespec_to_timespec64(*ts);
1248
1249	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1250	write_seqcount_begin(&tk_core.seq);
1251
1252	timekeeping_forward_now(tk);
1253
1254	/* Make sure the proposed value is valid */
1255	tmp = timespec64_add(tk_xtime(tk),  ts64);
1256	if (timespec64_compare(&tk->wall_to_monotonic, &ts64) > 0 ||
1257	    !timespec64_valid_strict(&tmp)) {
1258		ret = -EINVAL;
1259		goto error;
1260	}
1261
1262	tk_xtime_add(tk, &ts64);
1263	tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts64));
1264
1265error: /* even if we error out, we forwarded the time, so call update */
1266	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1267
1268	write_seqcount_end(&tk_core.seq);
1269	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1270
1271	/* signal hrtimers about time change */
1272	clock_was_set();
1273
1274	return ret;
1275}
1276EXPORT_SYMBOL(timekeeping_inject_offset);
1277
 
 
 
 
 
1278
1279/**
1280 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
 
 
 
 
 
 
 
1281 *
 
 
 
 
 
1282 */
1283s32 timekeeping_get_tai_offset(void)
1284{
1285	struct timekeeper *tk = &tk_core.timekeeper;
1286	unsigned int seq;
1287	s32 ret;
1288
1289	do {
1290		seq = read_seqcount_begin(&tk_core.seq);
1291		ret = tk->tai_offset;
1292	} while (read_seqcount_retry(&tk_core.seq, seq));
1293
1294	return ret;
 
 
 
 
1295}
1296
1297/**
1298 * __timekeeping_set_tai_offset - Lock free worker function
1299 *
1300 */
1301static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1302{
1303	tk->tai_offset = tai_offset;
1304	tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1305}
1306
1307/**
1308 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
1309 *
1310 */
1311void timekeeping_set_tai_offset(s32 tai_offset)
1312{
1313	struct timekeeper *tk = &tk_core.timekeeper;
1314	unsigned long flags;
1315
1316	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1317	write_seqcount_begin(&tk_core.seq);
1318	__timekeeping_set_tai_offset(tk, tai_offset);
1319	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1320	write_seqcount_end(&tk_core.seq);
1321	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1322	clock_was_set();
1323}
1324
1325/**
1326 * change_clocksource - Swaps clocksources if a new one is available
1327 *
1328 * Accumulates current time interval and initializes new clocksource
1329 */
1330static int change_clocksource(void *data)
1331{
1332	struct timekeeper *tk = &tk_core.timekeeper;
1333	struct clocksource *new, *old;
1334	unsigned long flags;
1335
1336	new = (struct clocksource *) data;
1337
1338	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1339	write_seqcount_begin(&tk_core.seq);
1340
1341	timekeeping_forward_now(tk);
1342	/*
1343	 * If the cs is in module, get a module reference. Succeeds
1344	 * for built-in code (owner == NULL) as well.
1345	 */
1346	if (try_module_get(new->owner)) {
1347		if (!new->enable || new->enable(new) == 0) {
1348			old = tk->tkr_mono.clock;
1349			tk_setup_internals(tk, new);
1350			if (old->disable)
1351				old->disable(old);
1352			module_put(old->owner);
1353		} else {
1354			module_put(new->owner);
1355		}
1356	}
1357	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1358
1359	write_seqcount_end(&tk_core.seq);
1360	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1361
1362	return 0;
1363}
1364
1365/**
1366 * timekeeping_notify - Install a new clock source
1367 * @clock:		pointer to the clock source
1368 *
1369 * This function is called from clocksource.c after a new, better clock
1370 * source has been registered. The caller holds the clocksource_mutex.
1371 */
1372int timekeeping_notify(struct clocksource *clock)
1373{
1374	struct timekeeper *tk = &tk_core.timekeeper;
1375
1376	if (tk->tkr_mono.clock == clock)
1377		return 0;
1378	stop_machine(change_clocksource, clock, NULL);
1379	tick_clock_notify();
1380	return tk->tkr_mono.clock == clock ? 0 : -1;
1381}
1382
1383/**
1384 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
1385 * @ts:		pointer to the timespec64 to be set
1386 *
1387 * Returns the raw monotonic time (completely un-modified by ntp)
1388 */
1389void getrawmonotonic64(struct timespec64 *ts)
1390{
1391	struct timekeeper *tk = &tk_core.timekeeper;
1392	struct timespec64 ts64;
1393	unsigned long seq;
1394	u64 nsecs;
1395
1396	do {
1397		seq = read_seqcount_begin(&tk_core.seq);
 
1398		nsecs = timekeeping_get_ns(&tk->tkr_raw);
1399		ts64 = tk->raw_time;
1400
1401	} while (read_seqcount_retry(&tk_core.seq, seq));
1402
1403	timespec64_add_ns(&ts64, nsecs);
1404	*ts = ts64;
1405}
1406EXPORT_SYMBOL(getrawmonotonic64);
1407
1408
1409/**
1410 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1411 */
1412int timekeeping_valid_for_hres(void)
1413{
1414	struct timekeeper *tk = &tk_core.timekeeper;
1415	unsigned long seq;
1416	int ret;
1417
1418	do {
1419		seq = read_seqcount_begin(&tk_core.seq);
1420
1421		ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1422
1423	} while (read_seqcount_retry(&tk_core.seq, seq));
1424
1425	return ret;
1426}
1427
1428/**
1429 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1430 */
1431u64 timekeeping_max_deferment(void)
1432{
1433	struct timekeeper *tk = &tk_core.timekeeper;
1434	unsigned long seq;
1435	u64 ret;
1436
1437	do {
1438		seq = read_seqcount_begin(&tk_core.seq);
1439
1440		ret = tk->tkr_mono.clock->max_idle_ns;
1441
1442	} while (read_seqcount_retry(&tk_core.seq, seq));
1443
1444	return ret;
1445}
1446
1447/**
1448 * read_persistent_clock -  Return time from the persistent clock.
1449 *
1450 * Weak dummy function for arches that do not yet support it.
1451 * Reads the time from the battery backed persistent clock.
1452 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1453 *
1454 *  XXX - Do be sure to remove it once all arches implement it.
1455 */
1456void __weak read_persistent_clock(struct timespec *ts)
1457{
1458	ts->tv_sec = 0;
1459	ts->tv_nsec = 0;
1460}
1461
1462void __weak read_persistent_clock64(struct timespec64 *ts64)
1463{
1464	struct timespec ts;
1465
1466	read_persistent_clock(&ts);
1467	*ts64 = timespec_to_timespec64(ts);
1468}
1469
1470/**
1471 * read_boot_clock64 -  Return time of the system start.
 
1472 *
1473 * Weak dummy function for arches that do not yet support it.
1474 * Function to read the exact time the system has been started.
1475 * Returns a timespec64 with tv_sec=0 and tv_nsec=0 if unsupported.
1476 *
1477 *  XXX - Do be sure to remove it once all arches implement it.
1478 */
1479void __weak read_boot_clock64(struct timespec64 *ts)
 
 
 
 
1480{
1481	ts->tv_sec = 0;
1482	ts->tv_nsec = 0;
1483}
1484
1485/* Flag for if timekeeping_resume() has injected sleeptime */
1486static bool sleeptime_injected;
 
 
 
 
 
 
 
 
 
 
 
 
1487
1488/* Flag for if there is a persistent clock on this platform */
1489static bool persistent_clock_exists;
1490
1491/*
1492 * timekeeping_init - Initializes the clocksource and common timekeeping values
1493 */
1494void __init timekeeping_init(void)
1495{
 
1496	struct timekeeper *tk = &tk_core.timekeeper;
1497	struct clocksource *clock;
1498	unsigned long flags;
1499	struct timespec64 now, boot, tmp;
1500
1501	read_persistent_clock64(&now);
1502	if (!timespec64_valid_strict(&now)) {
1503		pr_warn("WARNING: Persistent clock returned invalid value!\n"
1504			"         Check your CMOS/BIOS settings.\n");
1505		now.tv_sec = 0;
1506		now.tv_nsec = 0;
1507	} else if (now.tv_sec || now.tv_nsec)
1508		persistent_clock_exists = true;
1509
1510	read_boot_clock64(&boot);
1511	if (!timespec64_valid_strict(&boot)) {
1512		pr_warn("WARNING: Boot clock returned invalid value!\n"
1513			"         Check your CMOS/BIOS settings.\n");
1514		boot.tv_sec = 0;
1515		boot.tv_nsec = 0;
1516	}
1517
 
 
 
 
 
 
 
 
 
1518	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1519	write_seqcount_begin(&tk_core.seq);
1520	ntp_init();
1521
1522	clock = clocksource_default_clock();
1523	if (clock->enable)
1524		clock->enable(clock);
1525	tk_setup_internals(tk, clock);
1526
1527	tk_set_xtime(tk, &now);
1528	tk->raw_time.tv_sec = 0;
1529	tk->raw_time.tv_nsec = 0;
1530	if (boot.tv_sec == 0 && boot.tv_nsec == 0)
1531		boot = tk_xtime(tk);
1532
1533	set_normalized_timespec64(&tmp, -boot.tv_sec, -boot.tv_nsec);
1534	tk_set_wall_to_mono(tk, tmp);
1535
1536	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1537
1538	write_seqcount_end(&tk_core.seq);
1539	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1540}
1541
1542/* time in seconds when suspend began for persistent clock */
1543static struct timespec64 timekeeping_suspend_time;
1544
1545/**
1546 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1547 * @delta: pointer to a timespec delta value
1548 *
1549 * Takes a timespec offset measuring a suspend interval and properly
1550 * adds the sleep offset to the timekeeping variables.
1551 */
1552static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1553					   struct timespec64 *delta)
1554{
1555	if (!timespec64_valid_strict(delta)) {
1556		printk_deferred(KERN_WARNING
1557				"__timekeeping_inject_sleeptime: Invalid "
1558				"sleep delta value!\n");
1559		return;
1560	}
1561	tk_xtime_add(tk, delta);
1562	tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1563	tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1564	tk_debug_account_sleep_time(delta);
1565}
1566
1567#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1568/**
1569 * We have three kinds of time sources to use for sleep time
1570 * injection, the preference order is:
1571 * 1) non-stop clocksource
1572 * 2) persistent clock (ie: RTC accessible when irqs are off)
1573 * 3) RTC
1574 *
1575 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1576 * If system has neither 1) nor 2), 3) will be used finally.
1577 *
1578 *
1579 * If timekeeping has injected sleeptime via either 1) or 2),
1580 * 3) becomes needless, so in this case we don't need to call
1581 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1582 * means.
1583 */
1584bool timekeeping_rtc_skipresume(void)
1585{
1586	return sleeptime_injected;
1587}
1588
1589/**
1590 * 1) can be determined whether to use or not only when doing
1591 * timekeeping_resume() which is invoked after rtc_suspend(),
1592 * so we can't skip rtc_suspend() surely if system has 1).
1593 *
1594 * But if system has 2), 2) will definitely be used, so in this
1595 * case we don't need to call rtc_suspend(), and this is what
1596 * timekeeping_rtc_skipsuspend() means.
1597 */
1598bool timekeeping_rtc_skipsuspend(void)
1599{
1600	return persistent_clock_exists;
1601}
1602
1603/**
1604 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1605 * @delta: pointer to a timespec64 delta value
1606 *
1607 * This hook is for architectures that cannot support read_persistent_clock64
1608 * because their RTC/persistent clock is only accessible when irqs are enabled.
1609 * and also don't have an effective nonstop clocksource.
1610 *
1611 * This function should only be called by rtc_resume(), and allows
1612 * a suspend offset to be injected into the timekeeping values.
1613 */
1614void timekeeping_inject_sleeptime64(struct timespec64 *delta)
1615{
1616	struct timekeeper *tk = &tk_core.timekeeper;
1617	unsigned long flags;
1618
1619	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1620	write_seqcount_begin(&tk_core.seq);
1621
 
 
1622	timekeeping_forward_now(tk);
1623
1624	__timekeeping_inject_sleeptime(tk, delta);
1625
1626	timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1627
1628	write_seqcount_end(&tk_core.seq);
1629	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1630
1631	/* signal hrtimers about time change */
1632	clock_was_set();
1633}
1634#endif
1635
1636/**
1637 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1638 */
1639void timekeeping_resume(void)
1640{
1641	struct timekeeper *tk = &tk_core.timekeeper;
1642	struct clocksource *clock = tk->tkr_mono.clock;
1643	unsigned long flags;
1644	struct timespec64 ts_new, ts_delta;
1645	u64 cycle_now;
 
1646
1647	sleeptime_injected = false;
1648	read_persistent_clock64(&ts_new);
1649
1650	clockevents_resume();
1651	clocksource_resume();
1652
1653	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1654	write_seqcount_begin(&tk_core.seq);
1655
1656	/*
1657	 * After system resumes, we need to calculate the suspended time and
1658	 * compensate it for the OS time. There are 3 sources that could be
1659	 * used: Nonstop clocksource during suspend, persistent clock and rtc
1660	 * device.
1661	 *
1662	 * One specific platform may have 1 or 2 or all of them, and the
1663	 * preference will be:
1664	 *	suspend-nonstop clocksource -> persistent clock -> rtc
1665	 * The less preferred source will only be tried if there is no better
1666	 * usable source. The rtc part is handled separately in rtc core code.
1667	 */
1668	cycle_now = tk->tkr_mono.read(clock);
1669	if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
1670		cycle_now > tk->tkr_mono.cycle_last) {
1671		u64 nsec, cyc_delta;
1672
1673		cyc_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last,
1674					      tk->tkr_mono.mask);
1675		nsec = mul_u64_u32_shr(cyc_delta, clock->mult, clock->shift);
1676		ts_delta = ns_to_timespec64(nsec);
1677		sleeptime_injected = true;
1678	} else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1679		ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1680		sleeptime_injected = true;
1681	}
1682
1683	if (sleeptime_injected)
 
1684		__timekeeping_inject_sleeptime(tk, &ts_delta);
 
1685
1686	/* Re-base the last cycle value */
1687	tk->tkr_mono.cycle_last = cycle_now;
1688	tk->tkr_raw.cycle_last  = cycle_now;
1689
1690	tk->ntp_error = 0;
1691	timekeeping_suspended = 0;
1692	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1693	write_seqcount_end(&tk_core.seq);
1694	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1695
1696	touch_softlockup_watchdog();
1697
1698	tick_resume();
1699	hrtimers_resume();
1700}
1701
1702int timekeeping_suspend(void)
1703{
1704	struct timekeeper *tk = &tk_core.timekeeper;
1705	unsigned long flags;
1706	struct timespec64		delta, delta_delta;
1707	static struct timespec64	old_delta;
 
 
1708
1709	read_persistent_clock64(&timekeeping_suspend_time);
1710
1711	/*
1712	 * On some systems the persistent_clock can not be detected at
1713	 * timekeeping_init by its return value, so if we see a valid
1714	 * value returned, update the persistent_clock_exists flag.
1715	 */
1716	if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1717		persistent_clock_exists = true;
1718
 
 
1719	raw_spin_lock_irqsave(&timekeeper_lock, flags);
1720	write_seqcount_begin(&tk_core.seq);
1721	timekeeping_forward_now(tk);
1722	timekeeping_suspended = 1;
1723
 
 
 
 
 
 
 
 
 
1724	if (persistent_clock_exists) {
1725		/*
1726		 * To avoid drift caused by repeated suspend/resumes,
1727		 * which each can add ~1 second drift error,
1728		 * try to compensate so the difference in system time
1729		 * and persistent_clock time stays close to constant.
1730		 */
1731		delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1732		delta_delta = timespec64_sub(delta, old_delta);
1733		if (abs(delta_delta.tv_sec) >= 2) {
1734			/*
1735			 * if delta_delta is too large, assume time correction
1736			 * has occurred and set old_delta to the current delta.
1737			 */
1738			old_delta = delta;
1739		} else {
1740			/* Otherwise try to adjust old_system to compensate */
1741			timekeeping_suspend_time =
1742				timespec64_add(timekeeping_suspend_time, delta_delta);
1743		}
1744	}
1745
1746	timekeeping_update(tk, TK_MIRROR);
1747	halt_fast_timekeeper(tk);
1748	write_seqcount_end(&tk_core.seq);
1749	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1750
1751	tick_suspend();
1752	clocksource_suspend();
1753	clockevents_suspend();
1754
1755	return 0;
1756}
1757
1758/* sysfs resume/suspend bits for timekeeping */
1759static struct syscore_ops timekeeping_syscore_ops = {
1760	.resume		= timekeeping_resume,
1761	.suspend	= timekeeping_suspend,
1762};
1763
1764static int __init timekeeping_init_ops(void)
1765{
1766	register_syscore_ops(&timekeeping_syscore_ops);
1767	return 0;
1768}
1769device_initcall(timekeeping_init_ops);
1770
1771/*
1772 * Apply a multiplier adjustment to the timekeeper
1773 */
1774static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1775							 s64 offset,
1776							 bool negative,
1777							 int adj_scale)
1778{
1779	s64 interval = tk->cycle_interval;
1780	s32 mult_adj = 1;
1781
1782	if (negative) {
1783		mult_adj = -mult_adj;
 
1784		interval = -interval;
1785		offset  = -offset;
 
 
 
1786	}
1787	mult_adj <<= adj_scale;
1788	interval <<= adj_scale;
1789	offset <<= adj_scale;
1790
1791	/*
1792	 * So the following can be confusing.
1793	 *
1794	 * To keep things simple, lets assume mult_adj == 1 for now.
1795	 *
1796	 * When mult_adj != 1, remember that the interval and offset values
1797	 * have been appropriately scaled so the math is the same.
1798	 *
1799	 * The basic idea here is that we're increasing the multiplier
1800	 * by one, this causes the xtime_interval to be incremented by
1801	 * one cycle_interval. This is because:
1802	 *	xtime_interval = cycle_interval * mult
1803	 * So if mult is being incremented by one:
1804	 *	xtime_interval = cycle_interval * (mult + 1)
1805	 * Its the same as:
1806	 *	xtime_interval = (cycle_interval * mult) + cycle_interval
1807	 * Which can be shortened to:
1808	 *	xtime_interval += cycle_interval
1809	 *
1810	 * So offset stores the non-accumulated cycles. Thus the current
1811	 * time (in shifted nanoseconds) is:
1812	 *	now = (offset * adj) + xtime_nsec
1813	 * Now, even though we're adjusting the clock frequency, we have
1814	 * to keep time consistent. In other words, we can't jump back
1815	 * in time, and we also want to avoid jumping forward in time.
1816	 *
1817	 * So given the same offset value, we need the time to be the same
1818	 * both before and after the freq adjustment.
1819	 *	now = (offset * adj_1) + xtime_nsec_1
1820	 *	now = (offset * adj_2) + xtime_nsec_2
1821	 * So:
1822	 *	(offset * adj_1) + xtime_nsec_1 =
1823	 *		(offset * adj_2) + xtime_nsec_2
1824	 * And we know:
1825	 *	adj_2 = adj_1 + 1
1826	 * So:
1827	 *	(offset * adj_1) + xtime_nsec_1 =
1828	 *		(offset * (adj_1+1)) + xtime_nsec_2
1829	 *	(offset * adj_1) + xtime_nsec_1 =
1830	 *		(offset * adj_1) + offset + xtime_nsec_2
1831	 * Canceling the sides:
1832	 *	xtime_nsec_1 = offset + xtime_nsec_2
1833	 * Which gives us:
1834	 *	xtime_nsec_2 = xtime_nsec_1 - offset
1835	 * Which simplfies to:
1836	 *	xtime_nsec -= offset
1837	 *
1838	 * XXX - TODO: Doc ntp_error calculation.
1839	 */
1840	if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1841		/* NTP adjustment caused clocksource mult overflow */
1842		WARN_ON_ONCE(1);
1843		return;
1844	}
1845
1846	tk->tkr_mono.mult += mult_adj;
1847	tk->xtime_interval += interval;
1848	tk->tkr_mono.xtime_nsec -= offset;
1849	tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
1850}
1851
1852/*
1853 * Calculate the multiplier adjustment needed to match the frequency
1854 * specified by NTP
1855 */
1856static __always_inline void timekeeping_freqadjust(struct timekeeper *tk,
1857							s64 offset)
1858{
1859	s64 interval = tk->cycle_interval;
1860	s64 xinterval = tk->xtime_interval;
1861	u32 base = tk->tkr_mono.clock->mult;
1862	u32 max = tk->tkr_mono.clock->maxadj;
1863	u32 cur_adj = tk->tkr_mono.mult;
1864	s64 tick_error;
1865	bool negative;
1866	u32 adj_scale;
1867
1868	/* Remove any current error adj from freq calculation */
1869	if (tk->ntp_err_mult)
1870		xinterval -= tk->cycle_interval;
1871
1872	tk->ntp_tick = ntp_tick_length();
1873
1874	/* Calculate current error per tick */
1875	tick_error = ntp_tick_length() >> tk->ntp_error_shift;
1876	tick_error -= (xinterval + tk->xtime_remainder);
1877
1878	/* Don't worry about correcting it if its small */
1879	if (likely((tick_error >= 0) && (tick_error <= interval)))
1880		return;
1881
1882	/* preserve the direction of correction */
1883	negative = (tick_error < 0);
1884
1885	/* If any adjustment would pass the max, just return */
1886	if (negative && (cur_adj - 1) <= (base - max))
1887		return;
1888	if (!negative && (cur_adj + 1) >= (base + max))
1889		return;
1890	/*
1891	 * Sort out the magnitude of the correction, but
1892	 * avoid making so large a correction that we go
1893	 * over the max adjustment.
1894	 */
1895	adj_scale = 0;
1896	tick_error = abs(tick_error);
1897	while (tick_error > interval) {
1898		u32 adj = 1 << (adj_scale + 1);
1899
1900		/* Check if adjustment gets us within 1 unit from the max */
1901		if (negative && (cur_adj - adj) <= (base - max))
1902			break;
1903		if (!negative && (cur_adj + adj) >= (base + max))
1904			break;
1905
1906		adj_scale++;
1907		tick_error >>= 1;
1908	}
1909
1910	/* scale the corrections */
1911	timekeeping_apply_adjustment(tk, offset, negative, adj_scale);
1912}
1913
1914/*
1915 * Adjust the timekeeper's multiplier to the correct frequency
1916 * and also to reduce the accumulated error value.
1917 */
1918static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1919{
1920	/* Correct for the current frequency error */
1921	timekeeping_freqadjust(tk, offset);
1922
1923	/* Next make a small adjustment to fix any cumulative error */
1924	if (!tk->ntp_err_mult && (tk->ntp_error > 0)) {
1925		tk->ntp_err_mult = 1;
1926		timekeeping_apply_adjustment(tk, offset, 0, 0);
1927	} else if (tk->ntp_err_mult && (tk->ntp_error <= 0)) {
1928		/* Undo any existing error adjustment */
1929		timekeeping_apply_adjustment(tk, offset, 1, 0);
1930		tk->ntp_err_mult = 0;
 
 
1931	}
1932
 
 
 
 
 
 
 
 
 
 
 
1933	if (unlikely(tk->tkr_mono.clock->maxadj &&
1934		(abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
1935			> tk->tkr_mono.clock->maxadj))) {
1936		printk_once(KERN_WARNING
1937			"Adjusting %s more than 11%% (%ld vs %ld)\n",
1938			tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
1939			(long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
1940	}
1941
1942	/*
1943	 * It may be possible that when we entered this function, xtime_nsec
1944	 * was very small.  Further, if we're slightly speeding the clocksource
1945	 * in the code above, its possible the required corrective factor to
1946	 * xtime_nsec could cause it to underflow.
1947	 *
1948	 * Now, since we already accumulated the second, cannot simply roll
1949	 * the accumulated second back, since the NTP subsystem has been
1950	 * notified via second_overflow. So instead we push xtime_nsec forward
1951	 * by the amount we underflowed, and add that amount into the error.
1952	 *
1953	 * We'll correct this error next time through this function, when
1954	 * xtime_nsec is not as small.
1955	 */
1956	if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
1957		s64 neg = -(s64)tk->tkr_mono.xtime_nsec;
1958		tk->tkr_mono.xtime_nsec = 0;
1959		tk->ntp_error += neg << tk->ntp_error_shift;
 
1960	}
1961}
1962
1963/**
1964 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1965 *
1966 * Helper function that accumulates the nsecs greater than a second
1967 * from the xtime_nsec field to the xtime_secs field.
1968 * It also calls into the NTP code to handle leapsecond processing.
1969 *
1970 */
1971static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1972{
1973	u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
1974	unsigned int clock_set = 0;
1975
1976	while (tk->tkr_mono.xtime_nsec >= nsecps) {
1977		int leap;
1978
1979		tk->tkr_mono.xtime_nsec -= nsecps;
1980		tk->xtime_sec++;
1981
 
 
 
 
 
 
 
 
 
1982		/* Figure out if its a leap sec and apply if needed */
1983		leap = second_overflow(tk->xtime_sec);
1984		if (unlikely(leap)) {
1985			struct timespec64 ts;
1986
1987			tk->xtime_sec += leap;
1988
1989			ts.tv_sec = leap;
1990			ts.tv_nsec = 0;
1991			tk_set_wall_to_mono(tk,
1992				timespec64_sub(tk->wall_to_monotonic, ts));
1993
1994			__timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1995
1996			clock_set = TK_CLOCK_WAS_SET;
1997		}
1998	}
1999	return clock_set;
2000}
2001
2002/**
2003 * logarithmic_accumulation - shifted accumulation of cycles
2004 *
2005 * This functions accumulates a shifted interval of cycles into
2006 * into a shifted interval nanoseconds. Allows for O(log) accumulation
2007 * loop.
2008 *
2009 * Returns the unconsumed cycles.
2010 */
2011static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2012				    u32 shift, unsigned int *clock_set)
2013{
2014	u64 interval = tk->cycle_interval << shift;
2015	u64 raw_nsecs;
2016
2017	/* If the offset is smaller than a shifted interval, do nothing */
2018	if (offset < interval)
2019		return offset;
2020
2021	/* Accumulate one shifted interval */
2022	offset -= interval;
2023	tk->tkr_mono.cycle_last += interval;
2024	tk->tkr_raw.cycle_last  += interval;
2025
2026	tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2027	*clock_set |= accumulate_nsecs_to_secs(tk);
2028
2029	/* Accumulate raw time */
2030	raw_nsecs = (u64)tk->raw_interval << shift;
2031	raw_nsecs += tk->raw_time.tv_nsec;
2032	if (raw_nsecs >= NSEC_PER_SEC) {
2033		u64 raw_secs = raw_nsecs;
2034		raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
2035		tk->raw_time.tv_sec += raw_secs;
2036	}
2037	tk->raw_time.tv_nsec = raw_nsecs;
2038
2039	/* Accumulate error between NTP and clock interval */
2040	tk->ntp_error += tk->ntp_tick << shift;
2041	tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2042						(tk->ntp_error_shift + shift);
2043
2044	return offset;
2045}
2046
2047/**
2048 * update_wall_time - Uses the current clocksource to increment the wall time
2049 *
2050 */
2051void update_wall_time(void)
2052{
2053	struct timekeeper *real_tk = &tk_core.timekeeper;
2054	struct timekeeper *tk = &shadow_timekeeper;
2055	u64 offset;
2056	int shift = 0, maxshift;
2057	unsigned int clock_set = 0;
2058	unsigned long flags;
2059
2060	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2061
2062	/* Make sure we're fully resumed: */
2063	if (unlikely(timekeeping_suspended))
2064		goto out;
2065
2066#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
2067	offset = real_tk->cycle_interval;
 
 
 
2068#else
2069	offset = clocksource_delta(tk->tkr_mono.read(tk->tkr_mono.clock),
2070				   tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2071#endif
2072
2073	/* Check if there's really nothing to do */
2074	if (offset < real_tk->cycle_interval)
2075		goto out;
 
2076
2077	/* Do some additional sanity checking */
2078	timekeeping_check_update(real_tk, offset);
2079
2080	/*
2081	 * With NO_HZ we may have to accumulate many cycle_intervals
2082	 * (think "ticks") worth of time at once. To do this efficiently,
2083	 * we calculate the largest doubling multiple of cycle_intervals
2084	 * that is smaller than the offset.  We then accumulate that
2085	 * chunk in one go, and then try to consume the next smaller
2086	 * doubled multiple.
2087	 */
2088	shift = ilog2(offset) - ilog2(tk->cycle_interval);
2089	shift = max(0, shift);
2090	/* Bound shift to one less than what overflows tick_length */
2091	maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2092	shift = min(shift, maxshift);
2093	while (offset >= tk->cycle_interval) {
2094		offset = logarithmic_accumulation(tk, offset, shift,
2095							&clock_set);
2096		if (offset < tk->cycle_interval<<shift)
2097			shift--;
2098	}
2099
2100	/* correct the clock when NTP error is too big */
2101	timekeeping_adjust(tk, offset);
2102
2103	/*
2104	 * XXX This can be killed once everyone converts
2105	 * to the new update_vsyscall.
2106	 */
2107	old_vsyscall_fixup(tk);
2108
2109	/*
2110	 * Finally, make sure that after the rounding
2111	 * xtime_nsec isn't larger than NSEC_PER_SEC
2112	 */
2113	clock_set |= accumulate_nsecs_to_secs(tk);
2114
2115	write_seqcount_begin(&tk_core.seq);
2116	/*
2117	 * Update the real timekeeper.
2118	 *
2119	 * We could avoid this memcpy by switching pointers, but that
2120	 * requires changes to all other timekeeper usage sites as
2121	 * well, i.e. move the timekeeper pointer getter into the
2122	 * spinlocked/seqcount protected sections. And we trade this
2123	 * memcpy under the tk_core.seq against one before we start
2124	 * updating.
2125	 */
2126	timekeeping_update(tk, clock_set);
2127	memcpy(real_tk, tk, sizeof(*tk));
2128	/* The memcpy must come last. Do not put anything here! */
2129	write_seqcount_end(&tk_core.seq);
2130out:
2131	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2132	if (clock_set)
2133		/* Have to call _delayed version, since in irq context*/
2134		clock_was_set_delayed();
2135}
2136
2137/**
 
 
 
 
 
 
 
 
 
2138 * getboottime64 - Return the real time of system boot.
2139 * @ts:		pointer to the timespec64 to be set
2140 *
2141 * Returns the wall-time of boot in a timespec64.
2142 *
2143 * This is based on the wall_to_monotonic offset and the total suspend
2144 * time. Calls to settimeofday will affect the value returned (which
2145 * basically means that however wrong your real time clock is at boot time,
2146 * you get the right time here).
2147 */
2148void getboottime64(struct timespec64 *ts)
2149{
2150	struct timekeeper *tk = &tk_core.timekeeper;
2151	ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2152
2153	*ts = ktime_to_timespec64(t);
2154}
2155EXPORT_SYMBOL_GPL(getboottime64);
2156
2157unsigned long get_seconds(void)
2158{
2159	struct timekeeper *tk = &tk_core.timekeeper;
2160
2161	return tk->xtime_sec;
2162}
2163EXPORT_SYMBOL(get_seconds);
2164
2165struct timespec __current_kernel_time(void)
2166{
2167	struct timekeeper *tk = &tk_core.timekeeper;
2168
2169	return timespec64_to_timespec(tk_xtime(tk));
2170}
2171
2172struct timespec64 current_kernel_time64(void)
2173{
2174	struct timekeeper *tk = &tk_core.timekeeper;
2175	struct timespec64 now;
2176	unsigned long seq;
2177
2178	do {
2179		seq = read_seqcount_begin(&tk_core.seq);
2180
2181		now = tk_xtime(tk);
2182	} while (read_seqcount_retry(&tk_core.seq, seq));
2183
2184	return now;
2185}
2186EXPORT_SYMBOL(current_kernel_time64);
2187
2188struct timespec64 get_monotonic_coarse64(void)
2189{
2190	struct timekeeper *tk = &tk_core.timekeeper;
2191	struct timespec64 now, mono;
2192	unsigned long seq;
2193
2194	do {
2195		seq = read_seqcount_begin(&tk_core.seq);
2196
2197		now = tk_xtime(tk);
2198		mono = tk->wall_to_monotonic;
2199	} while (read_seqcount_retry(&tk_core.seq, seq));
2200
2201	set_normalized_timespec64(&now, now.tv_sec + mono.tv_sec,
2202				now.tv_nsec + mono.tv_nsec);
2203
2204	return now;
2205}
2206EXPORT_SYMBOL(get_monotonic_coarse64);
2207
2208/*
2209 * Must hold jiffies_lock
2210 */
2211void do_timer(unsigned long ticks)
2212{
2213	jiffies_64 += ticks;
2214	calc_global_load(ticks);
2215}
2216
2217/**
2218 * ktime_get_update_offsets_now - hrtimer helper
2219 * @cwsseq:	pointer to check and store the clock was set sequence number
2220 * @offs_real:	pointer to storage for monotonic -> realtime offset
2221 * @offs_boot:	pointer to storage for monotonic -> boottime offset
2222 * @offs_tai:	pointer to storage for monotonic -> clock tai offset
2223 *
2224 * Returns current monotonic time and updates the offsets if the
2225 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2226 * different.
2227 *
2228 * Called from hrtimer_interrupt() or retrigger_next_event()
2229 */
2230ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2231				     ktime_t *offs_boot, ktime_t *offs_tai)
2232{
2233	struct timekeeper *tk = &tk_core.timekeeper;
2234	unsigned int seq;
2235	ktime_t base;
2236	u64 nsecs;
2237
2238	do {
2239		seq = read_seqcount_begin(&tk_core.seq);
2240
2241		base = tk->tkr_mono.base;
2242		nsecs = timekeeping_get_ns(&tk->tkr_mono);
2243		base = ktime_add_ns(base, nsecs);
2244
2245		if (*cwsseq != tk->clock_was_set_seq) {
2246			*cwsseq = tk->clock_was_set_seq;
2247			*offs_real = tk->offs_real;
2248			*offs_boot = tk->offs_boot;
2249			*offs_tai = tk->offs_tai;
2250		}
2251
2252		/* Handle leapsecond insertion adjustments */
2253		if (unlikely(base >= tk->next_leap_ktime))
2254			*offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2255
2256	} while (read_seqcount_retry(&tk_core.seq, seq));
2257
2258	return base;
2259}
2260
2261/**
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2262 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2263 */
2264int do_adjtimex(struct timex *txc)
2265{
2266	struct timekeeper *tk = &tk_core.timekeeper;
 
2267	unsigned long flags;
2268	struct timespec64 ts;
2269	s32 orig_tai, tai;
2270	int ret;
2271
2272	/* Validate the data before disabling interrupts */
2273	ret = ntp_validate_timex(txc);
2274	if (ret)
2275		return ret;
2276
2277	if (txc->modes & ADJ_SETOFFSET) {
2278		struct timespec delta;
2279		delta.tv_sec  = txc->time.tv_sec;
2280		delta.tv_nsec = txc->time.tv_usec;
2281		if (!(txc->modes & ADJ_NANO))
2282			delta.tv_nsec *= 1000;
2283		ret = timekeeping_inject_offset(&delta);
2284		if (ret)
2285			return ret;
 
 
2286	}
2287
2288	getnstimeofday64(&ts);
 
 
2289
2290	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2291	write_seqcount_begin(&tk_core.seq);
2292
2293	orig_tai = tai = tk->tai_offset;
2294	ret = __do_adjtimex(txc, &ts, &tai);
2295
2296	if (tai != orig_tai) {
2297		__timekeeping_set_tai_offset(tk, tai);
2298		timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2299	}
2300	tk_update_leap_state(tk);
2301
2302	write_seqcount_end(&tk_core.seq);
2303	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2304
 
 
 
 
 
 
2305	if (tai != orig_tai)
2306		clock_was_set();
2307
2308	ntp_notify_cmos_timer();
2309
2310	return ret;
2311}
2312
2313#ifdef CONFIG_NTP_PPS
2314/**
2315 * hardpps() - Accessor function to NTP __hardpps function
2316 */
2317void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2318{
2319	unsigned long flags;
2320
2321	raw_spin_lock_irqsave(&timekeeper_lock, flags);
2322	write_seqcount_begin(&tk_core.seq);
2323
2324	__hardpps(phase_ts, raw_ts);
2325
2326	write_seqcount_end(&tk_core.seq);
2327	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2328}
2329EXPORT_SYMBOL(hardpps);
2330#endif
2331
2332/**
2333 * xtime_update() - advances the timekeeping infrastructure
2334 * @ticks:	number of ticks, that have elapsed since the last call.
2335 *
2336 * Must be called with interrupts disabled.
2337 */
2338void xtime_update(unsigned long ticks)
2339{
2340	write_seqlock(&jiffies_lock);
 
2341	do_timer(ticks);
2342	write_sequnlock(&jiffies_lock);
 
2343	update_wall_time();
2344}