1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
   4 *  Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
   5 *  Copyright(C) 2006-2007  Timesys Corp., Thomas Gleixner
   6 *
   7 *  High-resolution kernel timers
   8 *
   9 *  In contrast to the low-resolution timeout API, aka timer wheel,
  10 *  hrtimers provide finer resolution and accuracy depending on system
  11 *  configuration and capabilities.
  12 *
  13 *  Started by: Thomas Gleixner and Ingo Molnar
  14 *
  15 *  Credits:
  16 *	Based on the original timer wheel code
  17 *
  18 *	Help, testing, suggestions, bugfixes, improvements were
  19 *	provided by:
  20 *
  21 *	George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
  22 *	et. al.
  23 */
  24
  25#include <linux/cpu.h>
  26#include <linux/export.h>
  27#include <linux/percpu.h>
  28#include <linux/hrtimer.h>
  29#include <linux/notifier.h>
  30#include <linux/syscalls.h>
  31#include <linux/interrupt.h>
  32#include <linux/tick.h>
  33#include <linux/err.h>
  34#include <linux/debugobjects.h>
  35#include <linux/sched/signal.h>
  36#include <linux/sched/sysctl.h>
  37#include <linux/sched/rt.h>
  38#include <linux/sched/deadline.h>
  39#include <linux/sched/nohz.h>
  40#include <linux/sched/debug.h>
  41#include <linux/timer.h>
  42#include <linux/freezer.h>
  43#include <linux/compat.h>
  44
  45#include <linux/uaccess.h>
  46
  47#include <trace/events/timer.h>
  48
  49#include "tick-internal.h"
  50
  51/*
  52 * Masks for selecting the soft and hard context timers from
  53 * cpu_base->active
  54 */
  55#define MASK_SHIFT		(HRTIMER_BASE_MONOTONIC_SOFT)
  56#define HRTIMER_ACTIVE_HARD	((1U << MASK_SHIFT) - 1)
  57#define HRTIMER_ACTIVE_SOFT	(HRTIMER_ACTIVE_HARD << MASK_SHIFT)
  58#define HRTIMER_ACTIVE_ALL	(HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
  59
  60/*
  61 * The timer bases:
  62 *
  63 * There are more clockids than hrtimer bases. Thus, we index
  64 * into the timer bases by the hrtimer_base_type enum. When trying
  65 * to reach a base using a clockid, hrtimer_clockid_to_base()
  66 * is used to convert from clockid to the proper hrtimer_base_type.
  67 */
  68DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
  69{
  70	.lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
  71	.clock_base =
  72	{
  73		{
  74			.index = HRTIMER_BASE_MONOTONIC,
  75			.clockid = CLOCK_MONOTONIC,
  76			.get_time = &ktime_get,
  77		},
  78		{
  79			.index = HRTIMER_BASE_REALTIME,
  80			.clockid = CLOCK_REALTIME,
  81			.get_time = &ktime_get_real,
  82		},
  83		{
  84			.index = HRTIMER_BASE_BOOTTIME,
  85			.clockid = CLOCK_BOOTTIME,
  86			.get_time = &ktime_get_boottime,
  87		},
  88		{
  89			.index = HRTIMER_BASE_TAI,
  90			.clockid = CLOCK_TAI,
  91			.get_time = &ktime_get_clocktai,
  92		},
  93		{
  94			.index = HRTIMER_BASE_MONOTONIC_SOFT,
  95			.clockid = CLOCK_MONOTONIC,
  96			.get_time = &ktime_get,
  97		},
  98		{
  99			.index = HRTIMER_BASE_REALTIME_SOFT,
 100			.clockid = CLOCK_REALTIME,
 101			.get_time = &ktime_get_real,
 102		},
 103		{
 104			.index = HRTIMER_BASE_BOOTTIME_SOFT,
 105			.clockid = CLOCK_BOOTTIME,
 106			.get_time = &ktime_get_boottime,
 107		},
 108		{
 109			.index = HRTIMER_BASE_TAI_SOFT,
 110			.clockid = CLOCK_TAI,
 111			.get_time = &ktime_get_clocktai,
 112		},
 113	}
 114};
 115
 116static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
 117	/* Make sure we catch unsupported clockids */
 118	[0 ... MAX_CLOCKS - 1]	= HRTIMER_MAX_CLOCK_BASES,
 119
 120	[CLOCK_REALTIME]	= HRTIMER_BASE_REALTIME,
 121	[CLOCK_MONOTONIC]	= HRTIMER_BASE_MONOTONIC,
 122	[CLOCK_BOOTTIME]	= HRTIMER_BASE_BOOTTIME,
 123	[CLOCK_TAI]		= HRTIMER_BASE_TAI,
 124};
 125
 126/*
 127 * Functions and macros which are different for UP/SMP systems are kept in a
 128 * single place
 129 */
 130#ifdef CONFIG_SMP
 131
 132/*
 133 * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
 134 * such that hrtimer_callback_running() can unconditionally dereference
 135 * timer->base->cpu_base
 136 */
 137static struct hrtimer_cpu_base migration_cpu_base = {
 138	.clock_base = { {
 139		.cpu_base = &migration_cpu_base,
 140		.seq      = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq,
 141						     &migration_cpu_base.lock),
 142	}, },
 143};
 144
 145#define migration_base	migration_cpu_base.clock_base[0]
 146
 147static inline bool is_migration_base(struct hrtimer_clock_base *base)
 148{
 149	return base == &migration_base;
 150}
 151
 152/*
 153 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
 154 * means that all timers which are tied to this base via timer->base are
 155 * locked, and the base itself is locked too.
 156 *
 157 * So __run_timers/migrate_timers can safely modify all timers which could
 158 * be found on the lists/queues.
 159 *
 160 * When the timer's base is locked, and the timer removed from list, it is
 161 * possible to set timer->base = &migration_base and drop the lock: the timer
 162 * remains locked.
 163 */
 164static
 165struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
 166					     unsigned long *flags)
 167	__acquires(&timer->base->lock)
 168{
 169	struct hrtimer_clock_base *base;
 170
 171	for (;;) {
 172		base = READ_ONCE(timer->base);
 173		if (likely(base != &migration_base)) {
 174			raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
 175			if (likely(base == timer->base))
 176				return base;
 177			/* The timer has migrated to another CPU: */
 178			raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
 179		}
 180		cpu_relax();
 181	}
 182}
 183
 184/*
 185 * We do not migrate the timer when it is expiring before the next
 186 * event on the target cpu. When high resolution is enabled, we cannot
 187 * reprogram the target cpu hardware and we would cause it to fire
 188 * late. To keep it simple, we handle the high resolution enabled and
 189 * disabled case similar.
 190 *
 191 * Called with cpu_base->lock of target cpu held.
 192 */
 193static int
 194hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
 195{
 196	ktime_t expires;
 197
 198	expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
 199	return expires < new_base->cpu_base->expires_next;
 200}
 201
 202static inline
 203struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
 204					 int pinned)
 205{
 206#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
 207	if (static_branch_likely(&timers_migration_enabled) && !pinned)
 208		return &per_cpu(hrtimer_bases, get_nohz_timer_target());
 209#endif
 210	return base;
 211}
 212
 213/*
 214 * We switch the timer base to a power-optimized selected CPU target,
 215 * if:
 216 *	- NO_HZ_COMMON is enabled
 217 *	- timer migration is enabled
 218 *	- the timer callback is not running
 219 *	- the timer is not the first expiring timer on the new target
 220 *
 221 * If one of the above requirements is not fulfilled we move the timer
 222 * to the current CPU or leave it on the previously assigned CPU if
 223 * the timer callback is currently running.
 224 */
 225static inline struct hrtimer_clock_base *
 226switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
 227		    int pinned)
 228{
 229	struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
 230	struct hrtimer_clock_base *new_base;
 231	int basenum = base->index;
 232
 233	this_cpu_base = this_cpu_ptr(&hrtimer_bases);
 234	new_cpu_base = get_target_base(this_cpu_base, pinned);
 235again:
 236	new_base = &new_cpu_base->clock_base[basenum];
 237
 238	if (base != new_base) {
 239		/*
 240		 * We are trying to move timer to new_base.
 241		 * However we can't change timer's base while it is running,
 242		 * so we keep it on the same CPU. No hassle vs. reprogramming
 243		 * the event source in the high resolution case. The softirq
 244		 * code will take care of this when the timer function has
 245		 * completed. There is no conflict as we hold the lock until
 246		 * the timer is enqueued.
 247		 */
 248		if (unlikely(hrtimer_callback_running(timer)))
 249			return base;
 250
 251		/* See the comment in lock_hrtimer_base() */
 252		WRITE_ONCE(timer->base, &migration_base);
 253		raw_spin_unlock(&base->cpu_base->lock);
 254		raw_spin_lock(&new_base->cpu_base->lock);
 255
 256		if (new_cpu_base != this_cpu_base &&
 257		    hrtimer_check_target(timer, new_base)) {
 258			raw_spin_unlock(&new_base->cpu_base->lock);
 259			raw_spin_lock(&base->cpu_base->lock);
 260			new_cpu_base = this_cpu_base;
 261			WRITE_ONCE(timer->base, base);
 262			goto again;
 263		}
 264		WRITE_ONCE(timer->base, new_base);
 265	} else {
 266		if (new_cpu_base != this_cpu_base &&
 267		    hrtimer_check_target(timer, new_base)) {
 268			new_cpu_base = this_cpu_base;
 269			goto again;
 270		}
 271	}
 272	return new_base;
 273}
 274
 275#else /* CONFIG_SMP */
 276
 277static inline bool is_migration_base(struct hrtimer_clock_base *base)
 278{
 279	return false;
 280}
 281
 282static inline struct hrtimer_clock_base *
 283lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 284	__acquires(&timer->base->cpu_base->lock)
 285{
 286	struct hrtimer_clock_base *base = timer->base;
 287
 288	raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
 289
 290	return base;
 291}
 292
 293# define switch_hrtimer_base(t, b, p)	(b)
 294
 295#endif	/* !CONFIG_SMP */
 296
 297/*
 298 * Functions for the union type storage format of ktime_t which are
 299 * too large for inlining:
 300 */
 301#if BITS_PER_LONG < 64
 302/*
 303 * Divide a ktime value by a nanosecond value
 304 */
 305s64 __ktime_divns(const ktime_t kt, s64 div)
 306{
 307	int sft = 0;
 308	s64 dclc;
 309	u64 tmp;
 310
 311	dclc = ktime_to_ns(kt);
 312	tmp = dclc < 0 ? -dclc : dclc;
 313
 314	/* Make sure the divisor is less than 2^32: */
 315	while (div >> 32) {
 316		sft++;
 317		div >>= 1;
 318	}
 319	tmp >>= sft;
 320	do_div(tmp, (u32) div);
 321	return dclc < 0 ? -tmp : tmp;
 322}
 323EXPORT_SYMBOL_GPL(__ktime_divns);
 324#endif /* BITS_PER_LONG >= 64 */
 325
 326/*
 327 * Add two ktime values and do a safety check for overflow:
 328 */
 329ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
 330{
 331	ktime_t res = ktime_add_unsafe(lhs, rhs);
 332
 333	/*
 334	 * We use KTIME_SEC_MAX here, the maximum timeout which we can
 335	 * return to user space in a timespec:
 336	 */
 337	if (res < 0 || res < lhs || res < rhs)
 338		res = ktime_set(KTIME_SEC_MAX, 0);
 339
 340	return res;
 341}
 342
 343EXPORT_SYMBOL_GPL(ktime_add_safe);
 344
 345#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 346
 347static const struct debug_obj_descr hrtimer_debug_descr;
 348
 349static void *hrtimer_debug_hint(void *addr)
 350{
 351	return ((struct hrtimer *) addr)->function;
 352}
 353
 354/*
 355 * fixup_init is called when:
 356 * - an active object is initialized
 357 */
 358static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
 359{
 360	struct hrtimer *timer = addr;
 361
 362	switch (state) {
 363	case ODEBUG_STATE_ACTIVE:
 364		hrtimer_cancel(timer);
 365		debug_object_init(timer, &hrtimer_debug_descr);
 366		return true;
 367	default:
 368		return false;
 369	}
 370}
 371
 372/*
 373 * fixup_activate is called when:
 374 * - an active object is activated
 375 * - an unknown non-static object is activated
 376 */
 377static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
 378{
 379	switch (state) {
 380	case ODEBUG_STATE_ACTIVE:
 381		WARN_ON(1);
 382		fallthrough;
 383	default:
 384		return false;
 385	}
 386}
 387
 388/*
 389 * fixup_free is called when:
 390 * - an active object is freed
 391 */
 392static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
 393{
 394	struct hrtimer *timer = addr;
 395
 396	switch (state) {
 397	case ODEBUG_STATE_ACTIVE:
 398		hrtimer_cancel(timer);
 399		debug_object_free(timer, &hrtimer_debug_descr);
 400		return true;
 401	default:
 402		return false;
 403	}
 404}
 405
 406static const struct debug_obj_descr hrtimer_debug_descr = {
 407	.name		= "hrtimer",
 408	.debug_hint	= hrtimer_debug_hint,
 409	.fixup_init	= hrtimer_fixup_init,
 410	.fixup_activate	= hrtimer_fixup_activate,
 411	.fixup_free	= hrtimer_fixup_free,
 412};
 413
 414static inline void debug_hrtimer_init(struct hrtimer *timer)
 415{
 416	debug_object_init(timer, &hrtimer_debug_descr);
 417}
 418
 419static inline void debug_hrtimer_activate(struct hrtimer *timer,
 420					  enum hrtimer_mode mode)
 421{
 422	debug_object_activate(timer, &hrtimer_debug_descr);
 423}
 424
 425static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
 426{
 427	debug_object_deactivate(timer, &hrtimer_debug_descr);
 428}
 429
 
 
 
 
 
 430static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 431			   enum hrtimer_mode mode);
 432
 433void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
 434			   enum hrtimer_mode mode)
 435{
 436	debug_object_init_on_stack(timer, &hrtimer_debug_descr);
 437	__hrtimer_init(timer, clock_id, mode);
 438}
 439EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
 440
 441static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 442				   clockid_t clock_id, enum hrtimer_mode mode);
 443
 444void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
 445				   clockid_t clock_id, enum hrtimer_mode mode)
 446{
 447	debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
 448	__hrtimer_init_sleeper(sl, clock_id, mode);
 449}
 450EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
 451
 452void destroy_hrtimer_on_stack(struct hrtimer *timer)
 453{
 454	debug_object_free(timer, &hrtimer_debug_descr);
 455}
 456EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
 457
 458#else
 459
 460static inline void debug_hrtimer_init(struct hrtimer *timer) { }
 461static inline void debug_hrtimer_activate(struct hrtimer *timer,
 462					  enum hrtimer_mode mode) { }
 463static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
 464#endif
 465
 466static inline void
 467debug_init(struct hrtimer *timer, clockid_t clockid,
 468	   enum hrtimer_mode mode)
 469{
 470	debug_hrtimer_init(timer);
 471	trace_hrtimer_init(timer, clockid, mode);
 472}
 473
 474static inline void debug_activate(struct hrtimer *timer,
 475				  enum hrtimer_mode mode)
 476{
 477	debug_hrtimer_activate(timer, mode);
 478	trace_hrtimer_start(timer, mode);
 479}
 480
 481static inline void debug_deactivate(struct hrtimer *timer)
 482{
 483	debug_hrtimer_deactivate(timer);
 484	trace_hrtimer_cancel(timer);
 485}
 486
 487static struct hrtimer_clock_base *
 488__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
 489{
 490	unsigned int idx;
 491
 492	if (!*active)
 493		return NULL;
 494
 495	idx = __ffs(*active);
 496	*active &= ~(1U << idx);
 497
 498	return &cpu_base->clock_base[idx];
 499}
 500
 501#define for_each_active_base(base, cpu_base, active)	\
 502	while ((base = __next_base((cpu_base), &(active))))
 503
 504static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
 505					 const struct hrtimer *exclude,
 506					 unsigned int active,
 507					 ktime_t expires_next)
 508{
 509	struct hrtimer_clock_base *base;
 510	ktime_t expires;
 511
 512	for_each_active_base(base, cpu_base, active) {
 513		struct timerqueue_node *next;
 514		struct hrtimer *timer;
 515
 516		next = timerqueue_getnext(&base->active);
 517		timer = container_of(next, struct hrtimer, node);
 518		if (timer == exclude) {
 519			/* Get to the next timer in the queue. */
 520			next = timerqueue_iterate_next(next);
 521			if (!next)
 522				continue;
 523
 524			timer = container_of(next, struct hrtimer, node);
 525		}
 526		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 527		if (expires < expires_next) {
 528			expires_next = expires;
 529
 530			/* Skip cpu_base update if a timer is being excluded. */
 531			if (exclude)
 532				continue;
 533
 534			if (timer->is_soft)
 535				cpu_base->softirq_next_timer = timer;
 536			else
 537				cpu_base->next_timer = timer;
 538		}
 539	}
 540	/*
 541	 * clock_was_set() might have changed base->offset of any of
 542	 * the clock bases so the result might be negative. Fix it up
 543	 * to prevent a false positive in clockevents_program_event().
 544	 */
 545	if (expires_next < 0)
 546		expires_next = 0;
 547	return expires_next;
 548}
 549
 550/*
 551 * Recomputes cpu_base::*next_timer and returns the earliest expires_next
 552 * but does not set cpu_base::*expires_next, that is done by
 553 * hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
 554 * cpu_base::*expires_next right away, reprogramming logic would no longer
 555 * work.
 556 *
 557 * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
 558 * those timers will get run whenever the softirq gets handled, at the end of
 559 * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
 560 *
 561 * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
 562 * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
 563 * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
 564 *
 565 * @active_mask must be one of:
 566 *  - HRTIMER_ACTIVE_ALL,
 567 *  - HRTIMER_ACTIVE_SOFT, or
 568 *  - HRTIMER_ACTIVE_HARD.
 569 */
 570static ktime_t
 571__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
 572{
 573	unsigned int active;
 574	struct hrtimer *next_timer = NULL;
 575	ktime_t expires_next = KTIME_MAX;
 576
 577	if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
 578		active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
 579		cpu_base->softirq_next_timer = NULL;
 580		expires_next = __hrtimer_next_event_base(cpu_base, NULL,
 581							 active, KTIME_MAX);
 582
 583		next_timer = cpu_base->softirq_next_timer;
 584	}
 585
 586	if (active_mask & HRTIMER_ACTIVE_HARD) {
 587		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
 588		cpu_base->next_timer = next_timer;
 589		expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
 590							 expires_next);
 591	}
 592
 593	return expires_next;
 594}
 595
 596static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
 597{
 598	ktime_t expires_next, soft = KTIME_MAX;
 599
 600	/*
 601	 * If the soft interrupt has already been activated, ignore the
 602	 * soft bases. They will be handled in the already raised soft
 603	 * interrupt.
 604	 */
 605	if (!cpu_base->softirq_activated) {
 606		soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
 607		/*
 608		 * Update the soft expiry time. clock_settime() might have
 609		 * affected it.
 610		 */
 611		cpu_base->softirq_expires_next = soft;
 612	}
 613
 614	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
 615	/*
 616	 * If a softirq timer is expiring first, update cpu_base->next_timer
 617	 * and program the hardware with the soft expiry time.
 618	 */
 619	if (expires_next > soft) {
 620		cpu_base->next_timer = cpu_base->softirq_next_timer;
 621		expires_next = soft;
 622	}
 623
 624	return expires_next;
 625}
 626
 627static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
 628{
 629	ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
 630	ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
 631	ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
 632
 633	ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
 634					    offs_real, offs_boot, offs_tai);
 635
 636	base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
 637	base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
 638	base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
 639
 640	return now;
 641}
 642
 643/*
 644 * Is the high resolution mode active ?
 645 */
 646static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
 647{
 648	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
 649		cpu_base->hres_active : 0;
 650}
 651
 652static inline int hrtimer_hres_active(void)
 653{
 654	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
 655}
 656
 657static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
 658				struct hrtimer *next_timer,
 659				ktime_t expires_next)
 
 
 
 
 660{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 661	cpu_base->expires_next = expires_next;
 662
 663	/*
 664	 * If hres is not active, hardware does not have to be
 665	 * reprogrammed yet.
 666	 *
 667	 * If a hang was detected in the last timer interrupt then we
 668	 * leave the hang delay active in the hardware. We want the
 669	 * system to make progress. That also prevents the following
 670	 * scenario:
 671	 * T1 expires 50ms from now
 672	 * T2 expires 5s from now
 673	 *
 674	 * T1 is removed, so this code is called and would reprogram
 675	 * the hardware to 5s from now. Any hrtimer_start after that
 676	 * will not reprogram the hardware due to hang_detected being
 677	 * set. So we'd effectively block all timers until the T2 event
 678	 * fires.
 679	 */
 680	if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
 681		return;
 682
 683	tick_program_event(expires_next, 1);
 684}
 685
 686/*
 687 * Reprogram the event source with checking both queues for the
 688 * next event
 689 * Called with interrupts disabled and base->lock held
 690 */
 691static void
 692hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
 693{
 694	ktime_t expires_next;
 695
 696	expires_next = hrtimer_update_next_event(cpu_base);
 697
 698	if (skip_equal && expires_next == cpu_base->expires_next)
 699		return;
 700
 701	__hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next);
 702}
 703
 704/* High resolution timer related functions */
 705#ifdef CONFIG_HIGH_RES_TIMERS
 706
 707/*
 708 * High resolution timer enabled ?
 709 */
 710static bool hrtimer_hres_enabled __read_mostly  = true;
 711unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
 712EXPORT_SYMBOL_GPL(hrtimer_resolution);
 713
 714/*
 715 * Enable / Disable high resolution mode
 716 */
 717static int __init setup_hrtimer_hres(char *str)
 718{
 719	return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
 720}
 721
 722__setup("highres=", setup_hrtimer_hres);
 723
 724/*
 725 * hrtimer_high_res_enabled - query, if the highres mode is enabled
 726 */
 727static inline int hrtimer_is_hres_enabled(void)
 728{
 729	return hrtimer_hres_enabled;
 730}
 731
 732static void retrigger_next_event(void *arg);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 733
 734/*
 735 * Switch to high resolution mode
 736 */
 737static void hrtimer_switch_to_hres(void)
 738{
 739	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
 740
 741	if (tick_init_highres()) {
 742		pr_warn("Could not switch to high resolution mode on CPU %u\n",
 743			base->cpu);
 744		return;
 745	}
 746	base->hres_active = 1;
 747	hrtimer_resolution = HIGH_RES_NSEC;
 748
 749	tick_setup_sched_timer();
 750	/* "Retrigger" the interrupt to get things going */
 751	retrigger_next_event(NULL);
 752}
 753
 754#else
 
 
 
 755
 756static inline int hrtimer_is_hres_enabled(void) { return 0; }
 757static inline void hrtimer_switch_to_hres(void) { }
 758
 759#endif /* CONFIG_HIGH_RES_TIMERS */
 760/*
 761 * Retrigger next event is called after clock was set with interrupts
 762 * disabled through an SMP function call or directly from low level
 763 * resume code.
 764 *
 765 * This is only invoked when:
 766 *	- CONFIG_HIGH_RES_TIMERS is enabled.
 767 *	- CONFIG_NOHZ_COMMON is enabled
 768 *
 769 * For the other cases this function is empty and because the call sites
 770 * are optimized out it vanishes as well, i.e. no need for lots of
 771 * #ifdeffery.
 772 */
 773static void retrigger_next_event(void *arg)
 774{
 775	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
 
 776
 777	/*
 778	 * When high resolution mode or nohz is active, then the offsets of
 779	 * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the
 780	 * next tick will take care of that.
 781	 *
 782	 * If high resolution mode is active then the next expiring timer
 783	 * must be reevaluated and the clock event device reprogrammed if
 784	 * necessary.
 785	 *
 786	 * In the NOHZ case the update of the offset and the reevaluation
 787	 * of the next expiring timer is enough. The return from the SMP
 788	 * function call will take care of the reprogramming in case the
 789	 * CPU was in a NOHZ idle sleep.
 790	 */
 791	if (!__hrtimer_hres_active(base) && !tick_nohz_active)
 792		return;
 793
 794	raw_spin_lock(&base->lock);
 795	hrtimer_update_base(base);
 796	if (__hrtimer_hres_active(base))
 797		hrtimer_force_reprogram(base, 0);
 798	else
 799		hrtimer_update_next_event(base);
 800	raw_spin_unlock(&base->lock);
 801}
 802
 803/*
 804 * When a timer is enqueued and expires earlier than the already enqueued
 805 * timers, we have to check, whether it expires earlier than the timer for
 806 * which the clock event device was armed.
 807 *
 808 * Called with interrupts disabled and base->cpu_base.lock held
 809 */
 810static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
 811{
 812	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
 813	struct hrtimer_clock_base *base = timer->base;
 814	ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 815
 816	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
 817
 818	/*
 819	 * CLOCK_REALTIME timer might be requested with an absolute
 820	 * expiry time which is less than base->offset. Set it to 0.
 821	 */
 822	if (expires < 0)
 823		expires = 0;
 824
 825	if (timer->is_soft) {
 826		/*
 827		 * soft hrtimer could be started on a remote CPU. In this
 828		 * case softirq_expires_next needs to be updated on the
 829		 * remote CPU. The soft hrtimer will not expire before the
 830		 * first hard hrtimer on the remote CPU -
 831		 * hrtimer_check_target() prevents this case.
 832		 */
 833		struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
 834
 835		if (timer_cpu_base->softirq_activated)
 836			return;
 837
 838		if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
 839			return;
 840
 841		timer_cpu_base->softirq_next_timer = timer;
 842		timer_cpu_base->softirq_expires_next = expires;
 843
 844		if (!ktime_before(expires, timer_cpu_base->expires_next) ||
 845		    !reprogram)
 846			return;
 847	}
 848
 849	/*
 850	 * If the timer is not on the current cpu, we cannot reprogram
 851	 * the other cpus clock event device.
 852	 */
 853	if (base->cpu_base != cpu_base)
 854		return;
 855
 856	if (expires >= cpu_base->expires_next)
 857		return;
 858
 859	/*
 860	 * If the hrtimer interrupt is running, then it will reevaluate the
 861	 * clock bases and reprogram the clock event device.
 
 
 
 862	 */
 863	if (cpu_base->in_hrtirq)
 864		return;
 865
 866	cpu_base->next_timer = timer;
 867
 868	__hrtimer_reprogram(cpu_base, timer, expires);
 869}
 870
 871static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
 872			     unsigned int active)
 873{
 874	struct hrtimer_clock_base *base;
 875	unsigned int seq;
 876	ktime_t expires;
 877
 878	/*
 879	 * Update the base offsets unconditionally so the following
 880	 * checks whether the SMP function call is required works.
 881	 *
 882	 * The update is safe even when the remote CPU is in the hrtimer
 883	 * interrupt or the hrtimer soft interrupt and expiring affected
 884	 * bases. Either it will see the update before handling a base or
 885	 * it will see it when it finishes the processing and reevaluates
 886	 * the next expiring timer.
 887	 */
 888	seq = cpu_base->clock_was_set_seq;
 889	hrtimer_update_base(cpu_base);
 890
 891	/*
 892	 * If the sequence did not change over the update then the
 893	 * remote CPU already handled it.
 894	 */
 895	if (seq == cpu_base->clock_was_set_seq)
 896		return false;
 897
 898	/*
 899	 * If the remote CPU is currently handling an hrtimer interrupt, it
 900	 * will reevaluate the first expiring timer of all clock bases
 901	 * before reprogramming. Nothing to do here.
 902	 */
 903	if (cpu_base->in_hrtirq)
 904		return false;
 905
 906	/*
 907	 * Walk the affected clock bases and check whether the first expiring
 908	 * timer in a clock base is moving ahead of the first expiring timer of
 909	 * @cpu_base. If so, the IPI must be invoked because per CPU clock
 910	 * event devices cannot be remotely reprogrammed.
 911	 */
 912	active &= cpu_base->active_bases;
 913
 914	for_each_active_base(base, cpu_base, active) {
 915		struct timerqueue_node *next;
 916
 917		next = timerqueue_getnext(&base->active);
 918		expires = ktime_sub(next->expires, base->offset);
 919		if (expires < cpu_base->expires_next)
 920			return true;
 921
 922		/* Extra check for softirq clock bases */
 923		if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT)
 924			continue;
 925		if (cpu_base->softirq_activated)
 926			continue;
 927		if (expires < cpu_base->softirq_expires_next)
 928			return true;
 929	}
 930	return false;
 931}
 932
 933/*
 934 * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and
 935 * CLOCK_BOOTTIME (for late sleep time injection).
 936 *
 937 * This requires to update the offsets for these clocks
 938 * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this
 939 * also requires to eventually reprogram the per CPU clock event devices
 940 * when the change moves an affected timer ahead of the first expiring
 941 * timer on that CPU. Obviously remote per CPU clock event devices cannot
 942 * be reprogrammed. The other reason why an IPI has to be sent is when the
 943 * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets
 944 * in the tick, which obviously might be stopped, so this has to bring out
 945 * the remote CPU which might sleep in idle to get this sorted.
 946 */
 947void clock_was_set(unsigned int bases)
 948{
 949	struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
 950	cpumask_var_t mask;
 951	int cpu;
 952
 953	if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active)
 954		goto out_timerfd;
 955
 956	if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
 957		on_each_cpu(retrigger_next_event, NULL, 1);
 958		goto out_timerfd;
 959	}
 960
 961	/* Avoid interrupting CPUs if possible */
 962	cpus_read_lock();
 963	for_each_online_cpu(cpu) {
 964		unsigned long flags;
 965
 966		cpu_base = &per_cpu(hrtimer_bases, cpu);
 967		raw_spin_lock_irqsave(&cpu_base->lock, flags);
 968
 969		if (update_needs_ipi(cpu_base, bases))
 970			cpumask_set_cpu(cpu, mask);
 971
 972		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 973	}
 974
 975	preempt_disable();
 976	smp_call_function_many(mask, retrigger_next_event, NULL, 1);
 977	preempt_enable();
 978	cpus_read_unlock();
 979	free_cpumask_var(mask);
 980
 981out_timerfd:
 982	timerfd_clock_was_set();
 983}
 984
 985static void clock_was_set_work(struct work_struct *work)
 986{
 987	clock_was_set(CLOCK_SET_WALL);
 988}
 989
 990static DECLARE_WORK(hrtimer_work, clock_was_set_work);
 991
 992/*
 993 * Called from timekeeping code to reprogram the hrtimer interrupt device
 994 * on all cpus and to notify timerfd.
 995 */
 996void clock_was_set_delayed(void)
 997{
 998	schedule_work(&hrtimer_work);
 
 
 
 
 999}
1000
1001/*
1002 * Called during resume either directly from via timekeeping_resume()
1003 * or in the case of s2idle from tick_unfreeze() to ensure that the
1004 * hrtimers are up to date.
 
1005 */
1006void hrtimers_resume_local(void)
1007{
1008	lockdep_assert_irqs_disabled();
1009	/* Retrigger on the local CPU */
1010	retrigger_next_event(NULL);
 
 
1011}
1012
1013/*
1014 * Counterpart to lock_hrtimer_base above:
1015 */
1016static inline
1017void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
1018	__releases(&timer->base->cpu_base->lock)
1019{
1020	raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
1021}
1022
1023/**
1024 * hrtimer_forward - forward the timer expiry
1025 * @timer:	hrtimer to forward
1026 * @now:	forward past this time
1027 * @interval:	the interval to forward
1028 *
1029 * Forward the timer expiry so it will expire in the future.
1030 * Returns the number of overruns.
1031 *
1032 * Can be safely called from the callback function of @timer. If
1033 * called from other contexts @timer must neither be enqueued nor
1034 * running the callback and the caller needs to take care of
1035 * serialization.
1036 *
1037 * Note: This only updates the timer expiry value and does not requeue
1038 * the timer.
1039 */
1040u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
1041{
1042	u64 orun = 1;
1043	ktime_t delta;
1044
1045	delta = ktime_sub(now, hrtimer_get_expires(timer));
1046
1047	if (delta < 0)
1048		return 0;
1049
1050	if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
1051		return 0;
1052
1053	if (interval < hrtimer_resolution)
1054		interval = hrtimer_resolution;
1055
1056	if (unlikely(delta >= interval)) {
1057		s64 incr = ktime_to_ns(interval);
1058
1059		orun = ktime_divns(delta, incr);
1060		hrtimer_add_expires_ns(timer, incr * orun);
1061		if (hrtimer_get_expires_tv64(timer) > now)
1062			return orun;
1063		/*
1064		 * This (and the ktime_add() below) is the
1065		 * correction for exact:
1066		 */
1067		orun++;
1068	}
1069	hrtimer_add_expires(timer, interval);
1070
1071	return orun;
1072}
1073EXPORT_SYMBOL_GPL(hrtimer_forward);
1074
1075/*
1076 * enqueue_hrtimer - internal function to (re)start a timer
1077 *
1078 * The timer is inserted in expiry order. Insertion into the
1079 * red black tree is O(log(n)). Must hold the base lock.
1080 *
1081 * Returns 1 when the new timer is the leftmost timer in the tree.
1082 */
1083static int enqueue_hrtimer(struct hrtimer *timer,
1084			   struct hrtimer_clock_base *base,
1085			   enum hrtimer_mode mode)
1086{
1087	debug_activate(timer, mode);
1088	WARN_ON_ONCE(!base->cpu_base->online);
1089
1090	base->cpu_base->active_bases |= 1 << base->index;
1091
1092	/* Pairs with the lockless read in hrtimer_is_queued() */
1093	WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
1094
1095	return timerqueue_add(&base->active, &timer->node);
1096}
1097
1098/*
1099 * __remove_hrtimer - internal function to remove a timer
1100 *
1101 * Caller must hold the base lock.
1102 *
1103 * High resolution timer mode reprograms the clock event device when the
1104 * timer is the one which expires next. The caller can disable this by setting
1105 * reprogram to zero. This is useful, when the context does a reprogramming
1106 * anyway (e.g. timer interrupt)
1107 */
1108static void __remove_hrtimer(struct hrtimer *timer,
1109			     struct hrtimer_clock_base *base,
1110			     u8 newstate, int reprogram)
1111{
1112	struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1113	u8 state = timer->state;
1114
1115	/* Pairs with the lockless read in hrtimer_is_queued() */
1116	WRITE_ONCE(timer->state, newstate);
1117	if (!(state & HRTIMER_STATE_ENQUEUED))
1118		return;
1119
1120	if (!timerqueue_del(&base->active, &timer->node))
1121		cpu_base->active_bases &= ~(1 << base->index);
1122
1123	/*
1124	 * Note: If reprogram is false we do not update
1125	 * cpu_base->next_timer. This happens when we remove the first
1126	 * timer on a remote cpu. No harm as we never dereference
1127	 * cpu_base->next_timer. So the worst thing what can happen is
1128	 * an superfluous call to hrtimer_force_reprogram() on the
1129	 * remote cpu later on if the same timer gets enqueued again.
1130	 */
1131	if (reprogram && timer == cpu_base->next_timer)
1132		hrtimer_force_reprogram(cpu_base, 1);
1133}
1134
1135/*
1136 * remove hrtimer, called with base lock held
1137 */
1138static inline int
1139remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
1140	       bool restart, bool keep_local)
1141{
1142	u8 state = timer->state;
1143
1144	if (state & HRTIMER_STATE_ENQUEUED) {
1145		bool reprogram;
1146
1147		/*
1148		 * Remove the timer and force reprogramming when high
1149		 * resolution mode is active and the timer is on the current
1150		 * CPU. If we remove a timer on another CPU, reprogramming is
1151		 * skipped. The interrupt event on this CPU is fired and
1152		 * reprogramming happens in the interrupt handler. This is a
1153		 * rare case and less expensive than a smp call.
1154		 */
1155		debug_deactivate(timer);
1156		reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1157
1158		/*
1159		 * If the timer is not restarted then reprogramming is
1160		 * required if the timer is local. If it is local and about
1161		 * to be restarted, avoid programming it twice (on removal
1162		 * and a moment later when it's requeued).
1163		 */
1164		if (!restart)
1165			state = HRTIMER_STATE_INACTIVE;
1166		else
1167			reprogram &= !keep_local;
1168
1169		__remove_hrtimer(timer, base, state, reprogram);
1170		return 1;
1171	}
1172	return 0;
1173}
1174
1175static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1176					    const enum hrtimer_mode mode)
1177{
1178#ifdef CONFIG_TIME_LOW_RES
1179	/*
1180	 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1181	 * granular time values. For relative timers we add hrtimer_resolution
1182	 * (i.e. one jiffie) to prevent short timeouts.
1183	 */
1184	timer->is_rel = mode & HRTIMER_MODE_REL;
1185	if (timer->is_rel)
1186		tim = ktime_add_safe(tim, hrtimer_resolution);
1187#endif
1188	return tim;
1189}
1190
1191static void
1192hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1193{
1194	ktime_t expires;
1195
1196	/*
1197	 * Find the next SOFT expiration.
1198	 */
1199	expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1200
1201	/*
1202	 * reprogramming needs to be triggered, even if the next soft
1203	 * hrtimer expires at the same time than the next hard
1204	 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1205	 */
1206	if (expires == KTIME_MAX)
1207		return;
1208
1209	/*
1210	 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1211	 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1212	 */
1213	hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1214}
1215
1216static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1217				    u64 delta_ns, const enum hrtimer_mode mode,
1218				    struct hrtimer_clock_base *base)
1219{
1220	struct hrtimer_clock_base *new_base;
1221	bool force_local, first;
1222
1223	/*
1224	 * If the timer is on the local cpu base and is the first expiring
1225	 * timer then this might end up reprogramming the hardware twice
1226	 * (on removal and on enqueue). To avoid that by prevent the
1227	 * reprogram on removal, keep the timer local to the current CPU
1228	 * and enforce reprogramming after it is queued no matter whether
1229	 * it is the new first expiring timer again or not.
1230	 */
1231	force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1232	force_local &= base->cpu_base->next_timer == timer;
1233
1234	/*
1235	 * Remove an active timer from the queue. In case it is not queued
1236	 * on the current CPU, make sure that remove_hrtimer() updates the
1237	 * remote data correctly.
1238	 *
1239	 * If it's on the current CPU and the first expiring timer, then
1240	 * skip reprogramming, keep the timer local and enforce
1241	 * reprogramming later if it was the first expiring timer.  This
1242	 * avoids programming the underlying clock event twice (once at
1243	 * removal and once after enqueue).
1244	 */
1245	remove_hrtimer(timer, base, true, force_local);
1246
1247	if (mode & HRTIMER_MODE_REL)
1248		tim = ktime_add_safe(tim, base->get_time());
1249
1250	tim = hrtimer_update_lowres(timer, tim, mode);
1251
1252	hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1253
1254	/* Switch the timer base, if necessary: */
1255	if (!force_local) {
1256		new_base = switch_hrtimer_base(timer, base,
1257					       mode & HRTIMER_MODE_PINNED);
1258	} else {
1259		new_base = base;
1260	}
1261
1262	first = enqueue_hrtimer(timer, new_base, mode);
1263	if (!force_local)
1264		return first;
1265
1266	/*
1267	 * Timer was forced to stay on the current CPU to avoid
1268	 * reprogramming on removal and enqueue. Force reprogram the
1269	 * hardware by evaluating the new first expiring timer.
1270	 */
1271	hrtimer_force_reprogram(new_base->cpu_base, 1);
1272	return 0;
1273}
1274
1275/**
1276 * hrtimer_start_range_ns - (re)start an hrtimer
1277 * @timer:	the timer to be added
1278 * @tim:	expiry time
1279 * @delta_ns:	"slack" range for the timer
1280 * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
1281 *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1282 *		softirq based mode is considered for debug purpose only!
1283 */
1284void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1285			    u64 delta_ns, const enum hrtimer_mode mode)
1286{
1287	struct hrtimer_clock_base *base;
1288	unsigned long flags;
1289
1290	/*
1291	 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1292	 * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
1293	 * expiry mode because unmarked timers are moved to softirq expiry.
1294	 */
1295	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
1296		WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
1297	else
1298		WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
1299
1300	base = lock_hrtimer_base(timer, &flags);
1301
1302	if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1303		hrtimer_reprogram(timer, true);
1304
1305	unlock_hrtimer_base(timer, &flags);
1306}
1307EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1308
1309/**
1310 * hrtimer_try_to_cancel - try to deactivate a timer
1311 * @timer:	hrtimer to stop
1312 *
1313 * Returns:
1314 *
1315 *  *  0 when the timer was not active
1316 *  *  1 when the timer was active
1317 *  * -1 when the timer is currently executing the callback function and
1318 *    cannot be stopped
1319 */
1320int hrtimer_try_to_cancel(struct hrtimer *timer)
1321{
1322	struct hrtimer_clock_base *base;
1323	unsigned long flags;
1324	int ret = -1;
1325
1326	/*
1327	 * Check lockless first. If the timer is not active (neither
1328	 * enqueued nor running the callback, nothing to do here.  The
1329	 * base lock does not serialize against a concurrent enqueue,
1330	 * so we can avoid taking it.
1331	 */
1332	if (!hrtimer_active(timer))
1333		return 0;
1334
1335	base = lock_hrtimer_base(timer, &flags);
1336
1337	if (!hrtimer_callback_running(timer))
1338		ret = remove_hrtimer(timer, base, false, false);
1339
1340	unlock_hrtimer_base(timer, &flags);
1341
1342	return ret;
1343
1344}
1345EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1346
1347#ifdef CONFIG_PREEMPT_RT
1348static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1349{
1350	spin_lock_init(&base->softirq_expiry_lock);
1351}
1352
1353static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1354{
1355	spin_lock(&base->softirq_expiry_lock);
1356}
1357
1358static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
1359{
1360	spin_unlock(&base->softirq_expiry_lock);
1361}
1362
1363/*
1364 * The counterpart to hrtimer_cancel_wait_running().
1365 *
1366 * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
1367 * the timer callback to finish. Drop expiry_lock and reacquire it. That
1368 * allows the waiter to acquire the lock and make progress.
1369 */
1370static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
1371				      unsigned long flags)
1372{
1373	if (atomic_read(&cpu_base->timer_waiters)) {
1374		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1375		spin_unlock(&cpu_base->softirq_expiry_lock);
1376		spin_lock(&cpu_base->softirq_expiry_lock);
1377		raw_spin_lock_irq(&cpu_base->lock);
1378	}
1379}
1380
1381/*
1382 * This function is called on PREEMPT_RT kernels when the fast path
1383 * deletion of a timer failed because the timer callback function was
1384 * running.
1385 *
1386 * This prevents priority inversion: if the soft irq thread is preempted
1387 * in the middle of a timer callback, then calling del_timer_sync() can
1388 * lead to two issues:
1389 *
1390 *  - If the caller is on a remote CPU then it has to spin wait for the timer
1391 *    handler to complete. This can result in unbound priority inversion.
1392 *
1393 *  - If the caller originates from the task which preempted the timer
1394 *    handler on the same CPU, then spin waiting for the timer handler to
1395 *    complete is never going to end.
1396 */
1397void hrtimer_cancel_wait_running(const struct hrtimer *timer)
1398{
1399	/* Lockless read. Prevent the compiler from reloading it below */
1400	struct hrtimer_clock_base *base = READ_ONCE(timer->base);
1401
1402	/*
1403	 * Just relax if the timer expires in hard interrupt context or if
1404	 * it is currently on the migration base.
1405	 */
1406	if (!timer->is_soft || is_migration_base(base)) {
1407		cpu_relax();
1408		return;
1409	}
1410
1411	/*
1412	 * Mark the base as contended and grab the expiry lock, which is
1413	 * held by the softirq across the timer callback. Drop the lock
1414	 * immediately so the softirq can expire the next timer. In theory
1415	 * the timer could already be running again, but that's more than
1416	 * unlikely and just causes another wait loop.
1417	 */
1418	atomic_inc(&base->cpu_base->timer_waiters);
1419	spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
1420	atomic_dec(&base->cpu_base->timer_waiters);
1421	spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
1422}
1423#else
1424static inline void
1425hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1426static inline void
1427hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1428static inline void
1429hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
1430static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
1431					     unsigned long flags) { }
1432#endif
1433
1434/**
1435 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1436 * @timer:	the timer to be cancelled
1437 *
1438 * Returns:
1439 *  0 when the timer was not active
1440 *  1 when the timer was active
1441 */
1442int hrtimer_cancel(struct hrtimer *timer)
1443{
1444	int ret;
1445
1446	do {
1447		ret = hrtimer_try_to_cancel(timer);
1448
1449		if (ret < 0)
1450			hrtimer_cancel_wait_running(timer);
1451	} while (ret < 0);
1452	return ret;
1453}
1454EXPORT_SYMBOL_GPL(hrtimer_cancel);
1455
1456/**
1457 * __hrtimer_get_remaining - get remaining time for the timer
1458 * @timer:	the timer to read
1459 * @adjust:	adjust relative timers when CONFIG_TIME_LOW_RES=y
1460 */
1461ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1462{
1463	unsigned long flags;
1464	ktime_t rem;
1465
1466	lock_hrtimer_base(timer, &flags);
1467	if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1468		rem = hrtimer_expires_remaining_adjusted(timer);
1469	else
1470		rem = hrtimer_expires_remaining(timer);
1471	unlock_hrtimer_base(timer, &flags);
1472
1473	return rem;
1474}
1475EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1476
1477#ifdef CONFIG_NO_HZ_COMMON
1478/**
1479 * hrtimer_get_next_event - get the time until next expiry event
1480 *
1481 * Returns the next expiry time or KTIME_MAX if no timer is pending.
1482 */
1483u64 hrtimer_get_next_event(void)
1484{
1485	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1486	u64 expires = KTIME_MAX;
1487	unsigned long flags;
1488
1489	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1490
1491	if (!__hrtimer_hres_active(cpu_base))
1492		expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1493
1494	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1495
1496	return expires;
1497}
1498
1499/**
1500 * hrtimer_next_event_without - time until next expiry event w/o one timer
1501 * @exclude:	timer to exclude
1502 *
1503 * Returns the next expiry time over all timers except for the @exclude one or
1504 * KTIME_MAX if none of them is pending.
1505 */
1506u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1507{
1508	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1509	u64 expires = KTIME_MAX;
1510	unsigned long flags;
1511
1512	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1513
1514	if (__hrtimer_hres_active(cpu_base)) {
1515		unsigned int active;
1516
1517		if (!cpu_base->softirq_activated) {
1518			active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1519			expires = __hrtimer_next_event_base(cpu_base, exclude,
1520							    active, KTIME_MAX);
1521		}
1522		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1523		expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1524						    expires);
1525	}
1526
1527	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1528
1529	return expires;
1530}
1531#endif
1532
1533static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1534{
1535	if (likely(clock_id < MAX_CLOCKS)) {
1536		int base = hrtimer_clock_to_base_table[clock_id];
1537
1538		if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1539			return base;
1540	}
1541	WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1542	return HRTIMER_BASE_MONOTONIC;
1543}
1544
1545static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1546			   enum hrtimer_mode mode)
1547{
1548	bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1549	struct hrtimer_cpu_base *cpu_base;
1550	int base;
1551
1552	/*
1553	 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1554	 * marked for hard interrupt expiry mode are moved into soft
1555	 * interrupt context for latency reasons and because the callbacks
1556	 * can invoke functions which might sleep on RT, e.g. spin_lock().
1557	 */
1558	if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
1559		softtimer = true;
1560
1561	memset(timer, 0, sizeof(struct hrtimer));
1562
1563	cpu_base = raw_cpu_ptr(&hrtimer_bases);
1564
1565	/*
1566	 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1567	 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1568	 * ensure POSIX compliance.
1569	 */
1570	if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1571		clock_id = CLOCK_MONOTONIC;
1572
1573	base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1574	base += hrtimer_clockid_to_base(clock_id);
1575	timer->is_soft = softtimer;
1576	timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
1577	timer->base = &cpu_base->clock_base[base];
1578	timerqueue_init(&timer->node);
1579}
1580
1581/**
1582 * hrtimer_init - initialize a timer to the given clock
1583 * @timer:	the timer to be initialized
1584 * @clock_id:	the clock to be used
1585 * @mode:       The modes which are relevant for initialization:
1586 *              HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1587 *              HRTIMER_MODE_REL_SOFT
1588 *
1589 *              The PINNED variants of the above can be handed in,
1590 *              but the PINNED bit is ignored as pinning happens
1591 *              when the hrtimer is started
1592 */
1593void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1594		  enum hrtimer_mode mode)
1595{
1596	debug_init(timer, clock_id, mode);
1597	__hrtimer_init(timer, clock_id, mode);
1598}
1599EXPORT_SYMBOL_GPL(hrtimer_init);
1600
1601/*
1602 * A timer is active, when it is enqueued into the rbtree or the
1603 * callback function is running or it's in the state of being migrated
1604 * to another cpu.
1605 *
1606 * It is important for this function to not return a false negative.
1607 */
1608bool hrtimer_active(const struct hrtimer *timer)
1609{
1610	struct hrtimer_clock_base *base;
1611	unsigned int seq;
1612
1613	do {
1614		base = READ_ONCE(timer->base);
1615		seq = raw_read_seqcount_begin(&base->seq);
1616
1617		if (timer->state != HRTIMER_STATE_INACTIVE ||
1618		    base->running == timer)
1619			return true;
1620
1621	} while (read_seqcount_retry(&base->seq, seq) ||
1622		 base != READ_ONCE(timer->base));
1623
1624	return false;
1625}
1626EXPORT_SYMBOL_GPL(hrtimer_active);
1627
1628/*
1629 * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1630 * distinct sections:
1631 *
1632 *  - queued:	the timer is queued
1633 *  - callback:	the timer is being ran
1634 *  - post:	the timer is inactive or (re)queued
1635 *
1636 * On the read side we ensure we observe timer->state and cpu_base->running
1637 * from the same section, if anything changed while we looked at it, we retry.
1638 * This includes timer->base changing because sequence numbers alone are
1639 * insufficient for that.
1640 *
1641 * The sequence numbers are required because otherwise we could still observe
1642 * a false negative if the read side got smeared over multiple consecutive
1643 * __run_hrtimer() invocations.
1644 */
1645
1646static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1647			  struct hrtimer_clock_base *base,
1648			  struct hrtimer *timer, ktime_t *now,
1649			  unsigned long flags) __must_hold(&cpu_base->lock)
1650{
1651	enum hrtimer_restart (*fn)(struct hrtimer *);
1652	bool expires_in_hardirq;
1653	int restart;
1654
1655	lockdep_assert_held(&cpu_base->lock);
1656
1657	debug_deactivate(timer);
1658	base->running = timer;
1659
1660	/*
1661	 * Separate the ->running assignment from the ->state assignment.
1662	 *
1663	 * As with a regular write barrier, this ensures the read side in
1664	 * hrtimer_active() cannot observe base->running == NULL &&
1665	 * timer->state == INACTIVE.
1666	 */
1667	raw_write_seqcount_barrier(&base->seq);
1668
1669	__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1670	fn = timer->function;
1671
1672	/*
1673	 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1674	 * timer is restarted with a period then it becomes an absolute
1675	 * timer. If its not restarted it does not matter.
1676	 */
1677	if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1678		timer->is_rel = false;
1679
1680	/*
1681	 * The timer is marked as running in the CPU base, so it is
1682	 * protected against migration to a different CPU even if the lock
1683	 * is dropped.
1684	 */
1685	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1686	trace_hrtimer_expire_entry(timer, now);
1687	expires_in_hardirq = lockdep_hrtimer_enter(timer);
1688
1689	restart = fn(timer);
1690
1691	lockdep_hrtimer_exit(expires_in_hardirq);
1692	trace_hrtimer_expire_exit(timer);
1693	raw_spin_lock_irq(&cpu_base->lock);
1694
1695	/*
1696	 * Note: We clear the running state after enqueue_hrtimer and
1697	 * we do not reprogram the event hardware. Happens either in
1698	 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1699	 *
1700	 * Note: Because we dropped the cpu_base->lock above,
1701	 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1702	 * for us already.
1703	 */
1704	if (restart != HRTIMER_NORESTART &&
1705	    !(timer->state & HRTIMER_STATE_ENQUEUED))
1706		enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1707
1708	/*
1709	 * Separate the ->running assignment from the ->state assignment.
1710	 *
1711	 * As with a regular write barrier, this ensures the read side in
1712	 * hrtimer_active() cannot observe base->running.timer == NULL &&
1713	 * timer->state == INACTIVE.
1714	 */
1715	raw_write_seqcount_barrier(&base->seq);
1716
1717	WARN_ON_ONCE(base->running != timer);
1718	base->running = NULL;
1719}
1720
1721static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1722				 unsigned long flags, unsigned int active_mask)
1723{
1724	struct hrtimer_clock_base *base;
1725	unsigned int active = cpu_base->active_bases & active_mask;
1726
1727	for_each_active_base(base, cpu_base, active) {
1728		struct timerqueue_node *node;
1729		ktime_t basenow;
1730
1731		basenow = ktime_add(now, base->offset);
1732
1733		while ((node = timerqueue_getnext(&base->active))) {
1734			struct hrtimer *timer;
1735
1736			timer = container_of(node, struct hrtimer, node);
1737
1738			/*
1739			 * The immediate goal for using the softexpires is
1740			 * minimizing wakeups, not running timers at the
1741			 * earliest interrupt after their soft expiration.
1742			 * This allows us to avoid using a Priority Search
1743			 * Tree, which can answer a stabbing query for
1744			 * overlapping intervals and instead use the simple
1745			 * BST we already have.
1746			 * We don't add extra wakeups by delaying timers that
1747			 * are right-of a not yet expired timer, because that
1748			 * timer will have to trigger a wakeup anyway.
1749			 */
1750			if (basenow < hrtimer_get_softexpires_tv64(timer))
1751				break;
1752
1753			__run_hrtimer(cpu_base, base, timer, &basenow, flags);
1754			if (active_mask == HRTIMER_ACTIVE_SOFT)
1755				hrtimer_sync_wait_running(cpu_base, flags);
1756		}
1757	}
1758}
1759
1760static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1761{
1762	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1763	unsigned long flags;
1764	ktime_t now;
1765
1766	hrtimer_cpu_base_lock_expiry(cpu_base);
1767	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1768
1769	now = hrtimer_update_base(cpu_base);
1770	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1771
1772	cpu_base->softirq_activated = 0;
1773	hrtimer_update_softirq_timer(cpu_base, true);
1774
1775	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1776	hrtimer_cpu_base_unlock_expiry(cpu_base);
1777}
1778
1779#ifdef CONFIG_HIGH_RES_TIMERS
1780
1781/*
1782 * High resolution timer interrupt
1783 * Called with interrupts disabled
1784 */
1785void hrtimer_interrupt(struct clock_event_device *dev)
1786{
1787	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1788	ktime_t expires_next, now, entry_time, delta;
1789	unsigned long flags;
1790	int retries = 0;
1791
1792	BUG_ON(!cpu_base->hres_active);
1793	cpu_base->nr_events++;
1794	dev->next_event = KTIME_MAX;
1795
1796	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1797	entry_time = now = hrtimer_update_base(cpu_base);
1798retry:
1799	cpu_base->in_hrtirq = 1;
1800	/*
1801	 * We set expires_next to KTIME_MAX here with cpu_base->lock
1802	 * held to prevent that a timer is enqueued in our queue via
1803	 * the migration code. This does not affect enqueueing of
1804	 * timers which run their callback and need to be requeued on
1805	 * this CPU.
1806	 */
1807	cpu_base->expires_next = KTIME_MAX;
1808
1809	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1810		cpu_base->softirq_expires_next = KTIME_MAX;
1811		cpu_base->softirq_activated = 1;
1812		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1813	}
1814
1815	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1816
1817	/* Reevaluate the clock bases for the [soft] next expiry */
1818	expires_next = hrtimer_update_next_event(cpu_base);
1819	/*
1820	 * Store the new expiry value so the migration code can verify
1821	 * against it.
1822	 */
1823	cpu_base->expires_next = expires_next;
1824	cpu_base->in_hrtirq = 0;
1825	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1826
1827	/* Reprogramming necessary ? */
1828	if (!tick_program_event(expires_next, 0)) {
1829		cpu_base->hang_detected = 0;
1830		return;
1831	}
1832
1833	/*
1834	 * The next timer was already expired due to:
1835	 * - tracing
1836	 * - long lasting callbacks
1837	 * - being scheduled away when running in a VM
1838	 *
1839	 * We need to prevent that we loop forever in the hrtimer
1840	 * interrupt routine. We give it 3 attempts to avoid
1841	 * overreacting on some spurious event.
1842	 *
1843	 * Acquire base lock for updating the offsets and retrieving
1844	 * the current time.
1845	 */
1846	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1847	now = hrtimer_update_base(cpu_base);
1848	cpu_base->nr_retries++;
1849	if (++retries < 3)
1850		goto retry;
1851	/*
1852	 * Give the system a chance to do something else than looping
1853	 * here. We stored the entry time, so we know exactly how long
1854	 * we spent here. We schedule the next event this amount of
1855	 * time away.
1856	 */
1857	cpu_base->nr_hangs++;
1858	cpu_base->hang_detected = 1;
1859	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1860
1861	delta = ktime_sub(now, entry_time);
1862	if ((unsigned int)delta > cpu_base->max_hang_time)
1863		cpu_base->max_hang_time = (unsigned int) delta;
1864	/*
1865	 * Limit it to a sensible value as we enforce a longer
1866	 * delay. Give the CPU at least 100ms to catch up.
1867	 */
1868	if (delta > 100 * NSEC_PER_MSEC)
1869		expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1870	else
1871		expires_next = ktime_add(now, delta);
1872	tick_program_event(expires_next, 1);
1873	pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
1874}
1875
1876/* called with interrupts disabled */
1877static inline void __hrtimer_peek_ahead_timers(void)
1878{
1879	struct tick_device *td;
1880
1881	if (!hrtimer_hres_active())
1882		return;
1883
1884	td = this_cpu_ptr(&tick_cpu_device);
1885	if (td && td->evtdev)
1886		hrtimer_interrupt(td->evtdev);
1887}
1888
1889#else /* CONFIG_HIGH_RES_TIMERS */
1890
1891static inline void __hrtimer_peek_ahead_timers(void) { }
1892
1893#endif	/* !CONFIG_HIGH_RES_TIMERS */
1894
1895/*
1896 * Called from run_local_timers in hardirq context every jiffy
1897 */
1898void hrtimer_run_queues(void)
1899{
1900	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1901	unsigned long flags;
1902	ktime_t now;
1903
1904	if (__hrtimer_hres_active(cpu_base))
1905		return;
1906
1907	/*
1908	 * This _is_ ugly: We have to check periodically, whether we
1909	 * can switch to highres and / or nohz mode. The clocksource
1910	 * switch happens with xtime_lock held. Notification from
1911	 * there only sets the check bit in the tick_oneshot code,
1912	 * otherwise we might deadlock vs. xtime_lock.
1913	 */
1914	if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1915		hrtimer_switch_to_hres();
1916		return;
1917	}
1918
1919	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1920	now = hrtimer_update_base(cpu_base);
1921
1922	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1923		cpu_base->softirq_expires_next = KTIME_MAX;
1924		cpu_base->softirq_activated = 1;
1925		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1926	}
1927
1928	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1929	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1930}
1931
1932/*
1933 * Sleep related functions:
1934 */
1935static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1936{
1937	struct hrtimer_sleeper *t =
1938		container_of(timer, struct hrtimer_sleeper, timer);
1939	struct task_struct *task = t->task;
1940
1941	t->task = NULL;
1942	if (task)
1943		wake_up_process(task);
1944
1945	return HRTIMER_NORESTART;
1946}
1947
1948/**
1949 * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
1950 * @sl:		sleeper to be started
1951 * @mode:	timer mode abs/rel
1952 *
1953 * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
1954 * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
1955 */
1956void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
1957				   enum hrtimer_mode mode)
1958{
1959	/*
1960	 * Make the enqueue delivery mode check work on RT. If the sleeper
1961	 * was initialized for hard interrupt delivery, force the mode bit.
1962	 * This is a special case for hrtimer_sleepers because
1963	 * hrtimer_init_sleeper() determines the delivery mode on RT so the
1964	 * fiddling with this decision is avoided at the call sites.
1965	 */
1966	if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
1967		mode |= HRTIMER_MODE_HARD;
1968
1969	hrtimer_start_expires(&sl->timer, mode);
1970}
1971EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1972
1973static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
1974				   clockid_t clock_id, enum hrtimer_mode mode)
1975{
1976	/*
1977	 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1978	 * marked for hard interrupt expiry mode are moved into soft
1979	 * interrupt context either for latency reasons or because the
1980	 * hrtimer callback takes regular spinlocks or invokes other
1981	 * functions which are not suitable for hard interrupt context on
1982	 * PREEMPT_RT.
1983	 *
1984	 * The hrtimer_sleeper callback is RT compatible in hard interrupt
1985	 * context, but there is a latency concern: Untrusted userspace can
1986	 * spawn many threads which arm timers for the same expiry time on
1987	 * the same CPU. That causes a latency spike due to the wakeup of
1988	 * a gazillion threads.
1989	 *
1990	 * OTOH, privileged real-time user space applications rely on the
1991	 * low latency of hard interrupt wakeups. If the current task is in
1992	 * a real-time scheduling class, mark the mode for hard interrupt
1993	 * expiry.
1994	 */
1995	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1996		if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
1997			mode |= HRTIMER_MODE_HARD;
1998	}
1999
2000	__hrtimer_init(&sl->timer, clock_id, mode);
2001	sl->timer.function = hrtimer_wakeup;
2002	sl->task = current;
2003}
2004
2005/**
2006 * hrtimer_init_sleeper - initialize sleeper to the given clock
2007 * @sl:		sleeper to be initialized
2008 * @clock_id:	the clock to be used
2009 * @mode:	timer mode abs/rel
2010 */
2011void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
2012			  enum hrtimer_mode mode)
2013{
2014	debug_init(&sl->timer, clock_id, mode);
2015	__hrtimer_init_sleeper(sl, clock_id, mode);
2016
2017}
2018EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
2019
2020int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
2021{
2022	switch(restart->nanosleep.type) {
2023#ifdef CONFIG_COMPAT_32BIT_TIME
2024	case TT_COMPAT:
2025		if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
2026			return -EFAULT;
2027		break;
2028#endif
2029	case TT_NATIVE:
2030		if (put_timespec64(ts, restart->nanosleep.rmtp))
2031			return -EFAULT;
2032		break;
2033	default:
2034		BUG();
2035	}
2036	return -ERESTART_RESTARTBLOCK;
2037}
2038
2039static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
2040{
2041	struct restart_block *restart;
2042
2043	do {
2044		set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2045		hrtimer_sleeper_start_expires(t, mode);
2046
2047		if (likely(t->task))
2048			schedule();
2049
2050		hrtimer_cancel(&t->timer);
2051		mode = HRTIMER_MODE_ABS;
2052
2053	} while (t->task && !signal_pending(current));
2054
2055	__set_current_state(TASK_RUNNING);
2056
2057	if (!t->task)
2058		return 0;
2059
2060	restart = &current->restart_block;
2061	if (restart->nanosleep.type != TT_NONE) {
2062		ktime_t rem = hrtimer_expires_remaining(&t->timer);
2063		struct timespec64 rmt;
2064
2065		if (rem <= 0)
2066			return 0;
2067		rmt = ktime_to_timespec64(rem);
2068
2069		return nanosleep_copyout(restart, &rmt);
2070	}
2071	return -ERESTART_RESTARTBLOCK;
2072}
2073
2074static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
2075{
2076	struct hrtimer_sleeper t;
2077	int ret;
2078
2079	hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
2080				      HRTIMER_MODE_ABS);
2081	hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
2082	ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
2083	destroy_hrtimer_on_stack(&t.timer);
2084	return ret;
2085}
2086
2087long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
2088		       const clockid_t clockid)
2089{
2090	struct restart_block *restart;
2091	struct hrtimer_sleeper t;
2092	int ret = 0;
2093	u64 slack;
2094
2095	slack = current->timer_slack_ns;
2096	if (rt_task(current))
2097		slack = 0;
2098
2099	hrtimer_init_sleeper_on_stack(&t, clockid, mode);
2100	hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
2101	ret = do_nanosleep(&t, mode);
2102	if (ret != -ERESTART_RESTARTBLOCK)
2103		goto out;
2104
2105	/* Absolute timers do not update the rmtp value and restart: */
2106	if (mode == HRTIMER_MODE_ABS) {
2107		ret = -ERESTARTNOHAND;
2108		goto out;
2109	}
2110
2111	restart = &current->restart_block;
 
2112	restart->nanosleep.clockid = t.timer.base->clockid;
2113	restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
2114	set_restart_fn(restart, hrtimer_nanosleep_restart);
2115out:
2116	destroy_hrtimer_on_stack(&t.timer);
2117	return ret;
2118}
2119
2120#ifdef CONFIG_64BIT
2121
2122SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
2123		struct __kernel_timespec __user *, rmtp)
2124{
2125	struct timespec64 tu;
2126
2127	if (get_timespec64(&tu, rqtp))
2128		return -EFAULT;
2129
2130	if (!timespec64_valid(&tu))
2131		return -EINVAL;
2132
2133	current->restart_block.fn = do_no_restart_syscall;
2134	current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
2135	current->restart_block.nanosleep.rmtp = rmtp;
2136	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2137				 CLOCK_MONOTONIC);
2138}
2139
2140#endif
2141
2142#ifdef CONFIG_COMPAT_32BIT_TIME
2143
2144SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
2145		       struct old_timespec32 __user *, rmtp)
2146{
2147	struct timespec64 tu;
2148
2149	if (get_old_timespec32(&tu, rqtp))
2150		return -EFAULT;
2151
2152	if (!timespec64_valid(&tu))
2153		return -EINVAL;
2154
2155	current->restart_block.fn = do_no_restart_syscall;
2156	current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
2157	current->restart_block.nanosleep.compat_rmtp = rmtp;
2158	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2159				 CLOCK_MONOTONIC);
2160}
2161#endif
2162
2163/*
2164 * Functions related to boot-time initialization:
2165 */
2166int hrtimers_prepare_cpu(unsigned int cpu)
2167{
2168	struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
2169	int i;
2170
2171	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2172		struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
2173
2174		clock_b->cpu_base = cpu_base;
2175		seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
2176		timerqueue_init_head(&clock_b->active);
2177	}
2178
2179	cpu_base->cpu = cpu;
2180	cpu_base->active_bases = 0;
2181	cpu_base->hres_active = 0;
2182	cpu_base->hang_detected = 0;
2183	cpu_base->next_timer = NULL;
2184	cpu_base->softirq_next_timer = NULL;
2185	cpu_base->expires_next = KTIME_MAX;
2186	cpu_base->softirq_expires_next = KTIME_MAX;
2187	cpu_base->online = 1;
2188	hrtimer_cpu_base_init_expiry_lock(cpu_base);
2189	return 0;
2190}
2191
2192#ifdef CONFIG_HOTPLUG_CPU
2193
2194static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
2195				struct hrtimer_clock_base *new_base)
2196{
2197	struct hrtimer *timer;
2198	struct timerqueue_node *node;
2199
2200	while ((node = timerqueue_getnext(&old_base->active))) {
2201		timer = container_of(node, struct hrtimer, node);
2202		BUG_ON(hrtimer_callback_running(timer));
2203		debug_deactivate(timer);
2204
2205		/*
2206		 * Mark it as ENQUEUED not INACTIVE otherwise the
2207		 * timer could be seen as !active and just vanish away
2208		 * under us on another CPU
2209		 */
2210		__remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
2211		timer->base = new_base;
2212		/*
2213		 * Enqueue the timers on the new cpu. This does not
2214		 * reprogram the event device in case the timer
2215		 * expires before the earliest on this CPU, but we run
2216		 * hrtimer_interrupt after we migrated everything to
2217		 * sort out already expired timers and reprogram the
2218		 * event device.
2219		 */
2220		enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
2221	}
2222}
2223
2224int hrtimers_cpu_dying(unsigned int dying_cpu)
2225{
2226	struct hrtimer_cpu_base *old_base, *new_base;
2227	int i, ncpu = cpumask_first(cpu_active_mask);
2228
2229	tick_cancel_sched_timer(dying_cpu);
2230
2231	old_base = this_cpu_ptr(&hrtimer_bases);
2232	new_base = &per_cpu(hrtimer_bases, ncpu);
2233
2234	/*
 
 
 
 
 
 
 
 
 
2235	 * The caller is globally serialized and nobody else
2236	 * takes two locks at once, deadlock is not possible.
2237	 */
2238	raw_spin_lock(&old_base->lock);
2239	raw_spin_lock_nested(&new_base->lock, SINGLE_DEPTH_NESTING);
2240
2241	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2242		migrate_hrtimer_list(&old_base->clock_base[i],
2243				     &new_base->clock_base[i]);
2244	}
2245
2246	/*
2247	 * The migration might have changed the first expiring softirq
2248	 * timer on this CPU. Update it.
2249	 */
2250	__hrtimer_get_next_event(new_base, HRTIMER_ACTIVE_SOFT);
2251	/* Tell the other CPU to retrigger the next event */
2252	smp_call_function_single(ncpu, retrigger_next_event, NULL, 0);
2253
2254	raw_spin_unlock(&new_base->lock);
2255	old_base->online = 0;
2256	raw_spin_unlock(&old_base->lock);
 
2257
 
 
 
 
2258	return 0;
2259}
2260
2261#endif /* CONFIG_HOTPLUG_CPU */
2262
2263void __init hrtimers_init(void)
2264{
2265	hrtimers_prepare_cpu(smp_processor_id());
2266	open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
2267}
2268
2269/**
2270 * schedule_hrtimeout_range_clock - sleep until timeout
2271 * @expires:	timeout value (ktime_t)
2272 * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2273 * @mode:	timer mode
2274 * @clock_id:	timer clock to be used
2275 */
2276int __sched
2277schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
2278			       const enum hrtimer_mode mode, clockid_t clock_id)
2279{
2280	struct hrtimer_sleeper t;
2281
2282	/*
2283	 * Optimize when a zero timeout value is given. It does not
2284	 * matter whether this is an absolute or a relative time.
2285	 */
2286	if (expires && *expires == 0) {
2287		__set_current_state(TASK_RUNNING);
2288		return 0;
2289	}
2290
2291	/*
2292	 * A NULL parameter means "infinite"
2293	 */
2294	if (!expires) {
2295		schedule();
2296		return -EINTR;
2297	}
2298
2299	/*
2300	 * Override any slack passed by the user if under
2301	 * rt contraints.
2302	 */
2303	if (rt_task(current))
2304		delta = 0;
2305
2306	hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2307	hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2308	hrtimer_sleeper_start_expires(&t, mode);
2309
2310	if (likely(t.task))
2311		schedule();
2312
2313	hrtimer_cancel(&t.timer);
2314	destroy_hrtimer_on_stack(&t.timer);
2315
2316	__set_current_state(TASK_RUNNING);
2317
2318	return !t.task ? 0 : -EINTR;
2319}
2320EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
2321
2322/**
2323 * schedule_hrtimeout_range - sleep until timeout
2324 * @expires:	timeout value (ktime_t)
2325 * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2326 * @mode:	timer mode
2327 *
2328 * Make the current task sleep until the given expiry time has
2329 * elapsed. The routine will return immediately unless
2330 * the current task state has been set (see set_current_state()).
2331 *
2332 * The @delta argument gives the kernel the freedom to schedule the
2333 * actual wakeup to a time that is both power and performance friendly
2334 * for regular (non RT/DL) tasks.
2335 * The kernel give the normal best effort behavior for "@expires+@delta",
2336 * but may decide to fire the timer earlier, but no earlier than @expires.
2337 *
2338 * You can set the task state as follows -
2339 *
2340 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2341 * pass before the routine returns unless the current task is explicitly
2342 * woken up, (e.g. by wake_up_process()).
2343 *
2344 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2345 * delivered to the current task or the current task is explicitly woken
2346 * up.
2347 *
2348 * The current task state is guaranteed to be TASK_RUNNING when this
2349 * routine returns.
2350 *
2351 * Returns 0 when the timer has expired. If the task was woken before the
2352 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2353 * by an explicit wakeup, it returns -EINTR.
2354 */
2355int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2356				     const enum hrtimer_mode mode)
2357{
2358	return schedule_hrtimeout_range_clock(expires, delta, mode,
2359					      CLOCK_MONOTONIC);
2360}
2361EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2362
2363/**
2364 * schedule_hrtimeout - sleep until timeout
2365 * @expires:	timeout value (ktime_t)
2366 * @mode:	timer mode
2367 *
2368 * Make the current task sleep until the given expiry time has
2369 * elapsed. The routine will return immediately unless
2370 * the current task state has been set (see set_current_state()).
2371 *
2372 * You can set the task state as follows -
2373 *
2374 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2375 * pass before the routine returns unless the current task is explicitly
2376 * woken up, (e.g. by wake_up_process()).
2377 *
2378 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2379 * delivered to the current task or the current task is explicitly woken
2380 * up.
2381 *
2382 * The current task state is guaranteed to be TASK_RUNNING when this
2383 * routine returns.
2384 *
2385 * Returns 0 when the timer has expired. If the task was woken before the
2386 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2387 * by an explicit wakeup, it returns -EINTR.
2388 */
2389int __sched schedule_hrtimeout(ktime_t *expires,
2390			       const enum hrtimer_mode mode)
2391{
2392	return schedule_hrtimeout_range(expires, 0, mode);
2393}
2394EXPORT_SYMBOL_GPL(schedule_hrtimeout);