1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Implement CPU time clocks for the POSIX clock interface.
4  */
5 
6 #include <linux/sched/signal.h>
7 #include <linux/sched/cputime.h>
8 #include <linux/posix-timers.h>
9 #include <linux/errno.h>
10 #include <linux/math64.h>
11 #include <linux/uaccess.h>
12 #include <linux/kernel_stat.h>
13 #include <trace/events/timer.h>
14 #include <linux/tick.h>
15 #include <linux/workqueue.h>
16 #include <linux/compat.h>
17 #include <linux/sched/deadline.h>
18 
19 #include "posix-timers.h"
20 
21 static void posix_cpu_timer_rearm(struct k_itimer *timer);
22 
23 /*
24  * Called after updating RLIMIT_CPU to run cpu timer and update
25  * tsk->signal->cputime_expires expiration cache if necessary. Needs
26  * siglock protection since other code may update expiration cache as
27  * well.
28  */
29 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
30 {
31 	u64 nsecs = rlim_new * NSEC_PER_SEC;
32 
33 	spin_lock_irq(&task->sighand->siglock);
34 	set_process_cpu_timer(task, CPUCLOCK_PROF, &nsecs, NULL);
35 	spin_unlock_irq(&task->sighand->siglock);
36 }
37 
38 static int check_clock(const clockid_t which_clock)
39 {
40 	int error = 0;
41 	struct task_struct *p;
42 	const pid_t pid = CPUCLOCK_PID(which_clock);
43 
44 	if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
45 		return -EINVAL;
46 
47 	if (pid == 0)
48 		return 0;
49 
50 	rcu_read_lock();
51 	p = find_task_by_vpid(pid);
52 	if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
53 		   same_thread_group(p, current) : has_group_leader_pid(p))) {
54 		error = -EINVAL;
55 	}
56 	rcu_read_unlock();
57 
58 	return error;
59 }
60 
61 /*
62  * Update expiry time from increment, and increase overrun count,
63  * given the current clock sample.
64  */
65 static void bump_cpu_timer(struct k_itimer *timer, u64 now)
66 {
67 	int i;
68 	u64 delta, incr;
69 
70 	if (timer->it.cpu.incr == 0)
71 		return;
72 
73 	if (now < timer->it.cpu.expires)
74 		return;
75 
76 	incr = timer->it.cpu.incr;
77 	delta = now + incr - timer->it.cpu.expires;
78 
79 	/* Don't use (incr*2 < delta), incr*2 might overflow. */
80 	for (i = 0; incr < delta - incr; i++)
81 		incr = incr << 1;
82 
83 	for (; i >= 0; incr >>= 1, i--) {
84 		if (delta < incr)
85 			continue;
86 
87 		timer->it.cpu.expires += incr;
88 		timer->it_overrun += 1 << i;
89 		delta -= incr;
90 	}
91 }
92 
93 /**
94  * task_cputime_zero - Check a task_cputime struct for all zero fields.
95  *
96  * @cputime:	The struct to compare.
97  *
98  * Checks @cputime to see if all fields are zero.  Returns true if all fields
99  * are zero, false if any field is nonzero.
100  */
101 static inline int task_cputime_zero(const struct task_cputime *cputime)
102 {
103 	if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
104 		return 1;
105 	return 0;
106 }
107 
108 static inline u64 prof_ticks(struct task_struct *p)
109 {
110 	u64 utime, stime;
111 
112 	task_cputime(p, &utime, &stime);
113 
114 	return utime + stime;
115 }
116 static inline u64 virt_ticks(struct task_struct *p)
117 {
118 	u64 utime, stime;
119 
120 	task_cputime(p, &utime, &stime);
121 
122 	return utime;
123 }
124 
125 static int
126 posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
127 {
128 	int error = check_clock(which_clock);
129 	if (!error) {
130 		tp->tv_sec = 0;
131 		tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
132 		if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
133 			/*
134 			 * If sched_clock is using a cycle counter, we
135 			 * don't have any idea of its true resolution
136 			 * exported, but it is much more than 1s/HZ.
137 			 */
138 			tp->tv_nsec = 1;
139 		}
140 	}
141 	return error;
142 }
143 
144 static int
145 posix_cpu_clock_set(const clockid_t which_clock, const struct timespec64 *tp)
146 {
147 	/*
148 	 * You can never reset a CPU clock, but we check for other errors
149 	 * in the call before failing with EPERM.
150 	 */
151 	int error = check_clock(which_clock);
152 	if (error == 0) {
153 		error = -EPERM;
154 	}
155 	return error;
156 }
157 
158 
159 /*
160  * Sample a per-thread clock for the given task.
161  */
162 static int cpu_clock_sample(const clockid_t which_clock,
163 			    struct task_struct *p, u64 *sample)
164 {
165 	switch (CPUCLOCK_WHICH(which_clock)) {
166 	default:
167 		return -EINVAL;
168 	case CPUCLOCK_PROF:
169 		*sample = prof_ticks(p);
170 		break;
171 	case CPUCLOCK_VIRT:
172 		*sample = virt_ticks(p);
173 		break;
174 	case CPUCLOCK_SCHED:
175 		*sample = task_sched_runtime(p);
176 		break;
177 	}
178 	return 0;
179 }
180 
181 /*
182  * Set cputime to sum_cputime if sum_cputime > cputime. Use cmpxchg
183  * to avoid race conditions with concurrent updates to cputime.
184  */
185 static inline void __update_gt_cputime(atomic64_t *cputime, u64 sum_cputime)
186 {
187 	u64 curr_cputime;
188 retry:
189 	curr_cputime = atomic64_read(cputime);
190 	if (sum_cputime > curr_cputime) {
191 		if (atomic64_cmpxchg(cputime, curr_cputime, sum_cputime) != curr_cputime)
192 			goto retry;
193 	}
194 }
195 
196 static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic, struct task_cputime *sum)
197 {
198 	__update_gt_cputime(&cputime_atomic->utime, sum->utime);
199 	__update_gt_cputime(&cputime_atomic->stime, sum->stime);
200 	__update_gt_cputime(&cputime_atomic->sum_exec_runtime, sum->sum_exec_runtime);
201 }
202 
203 /* Sample task_cputime_atomic values in "atomic_timers", store results in "times". */
204 static inline void sample_cputime_atomic(struct task_cputime *times,
205 					 struct task_cputime_atomic *atomic_times)
206 {
207 	times->utime = atomic64_read(&atomic_times->utime);
208 	times->stime = atomic64_read(&atomic_times->stime);
209 	times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime);
210 }
211 
212 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
213 {
214 	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
215 	struct task_cputime sum;
216 
217 	/* Check if cputimer isn't running. This is accessed without locking. */
218 	if (!READ_ONCE(cputimer->running)) {
219 		/*
220 		 * The POSIX timer interface allows for absolute time expiry
221 		 * values through the TIMER_ABSTIME flag, therefore we have
222 		 * to synchronize the timer to the clock every time we start it.
223 		 */
224 		thread_group_cputime(tsk, &sum);
225 		update_gt_cputime(&cputimer->cputime_atomic, &sum);
226 
227 		/*
228 		 * We're setting cputimer->running without a lock. Ensure
229 		 * this only gets written to in one operation. We set
230 		 * running after update_gt_cputime() as a small optimization,
231 		 * but barriers are not required because update_gt_cputime()
232 		 * can handle concurrent updates.
233 		 */
234 		WRITE_ONCE(cputimer->running, true);
235 	}
236 	sample_cputime_atomic(times, &cputimer->cputime_atomic);
237 }
238 
239 /*
240  * Sample a process (thread group) clock for the given group_leader task.
241  * Must be called with task sighand lock held for safe while_each_thread()
242  * traversal.
243  */
244 static int cpu_clock_sample_group(const clockid_t which_clock,
245 				  struct task_struct *p,
246 				  u64 *sample)
247 {
248 	struct task_cputime cputime;
249 
250 	switch (CPUCLOCK_WHICH(which_clock)) {
251 	default:
252 		return -EINVAL;
253 	case CPUCLOCK_PROF:
254 		thread_group_cputime(p, &cputime);
255 		*sample = cputime.utime + cputime.stime;
256 		break;
257 	case CPUCLOCK_VIRT:
258 		thread_group_cputime(p, &cputime);
259 		*sample = cputime.utime;
260 		break;
261 	case CPUCLOCK_SCHED:
262 		thread_group_cputime(p, &cputime);
263 		*sample = cputime.sum_exec_runtime;
264 		break;
265 	}
266 	return 0;
267 }
268 
269 static int posix_cpu_clock_get_task(struct task_struct *tsk,
270 				    const clockid_t which_clock,
271 				    struct timespec64 *tp)
272 {
273 	int err = -EINVAL;
274 	u64 rtn;
275 
276 	if (CPUCLOCK_PERTHREAD(which_clock)) {
277 		if (same_thread_group(tsk, current))
278 			err = cpu_clock_sample(which_clock, tsk, &rtn);
279 	} else {
280 		if (tsk == current || thread_group_leader(tsk))
281 			err = cpu_clock_sample_group(which_clock, tsk, &rtn);
282 	}
283 
284 	if (!err)
285 		*tp = ns_to_timespec64(rtn);
286 
287 	return err;
288 }
289 
290 
291 static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec64 *tp)
292 {
293 	const pid_t pid = CPUCLOCK_PID(which_clock);
294 	int err = -EINVAL;
295 
296 	if (pid == 0) {
297 		/*
298 		 * Special case constant value for our own clocks.
299 		 * We don't have to do any lookup to find ourselves.
300 		 */
301 		err = posix_cpu_clock_get_task(current, which_clock, tp);
302 	} else {
303 		/*
304 		 * Find the given PID, and validate that the caller
305 		 * should be able to see it.
306 		 */
307 		struct task_struct *p;
308 		rcu_read_lock();
309 		p = find_task_by_vpid(pid);
310 		if (p)
311 			err = posix_cpu_clock_get_task(p, which_clock, tp);
312 		rcu_read_unlock();
313 	}
314 
315 	return err;
316 }
317 
318 /*
319  * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
320  * This is called from sys_timer_create() and do_cpu_nanosleep() with the
321  * new timer already all-zeros initialized.
322  */
323 static int posix_cpu_timer_create(struct k_itimer *new_timer)
324 {
325 	int ret = 0;
326 	const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
327 	struct task_struct *p;
328 
329 	if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
330 		return -EINVAL;
331 
332 	new_timer->kclock = &clock_posix_cpu;
333 
334 	INIT_LIST_HEAD(&new_timer->it.cpu.entry);
335 
336 	rcu_read_lock();
337 	if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
338 		if (pid == 0) {
339 			p = current;
340 		} else {
341 			p = find_task_by_vpid(pid);
342 			if (p && !same_thread_group(p, current))
343 				p = NULL;
344 		}
345 	} else {
346 		if (pid == 0) {
347 			p = current->group_leader;
348 		} else {
349 			p = find_task_by_vpid(pid);
350 			if (p && !has_group_leader_pid(p))
351 				p = NULL;
352 		}
353 	}
354 	new_timer->it.cpu.task = p;
355 	if (p) {
356 		get_task_struct(p);
357 	} else {
358 		ret = -EINVAL;
359 	}
360 	rcu_read_unlock();
361 
362 	return ret;
363 }
364 
365 /*
366  * Clean up a CPU-clock timer that is about to be destroyed.
367  * This is called from timer deletion with the timer already locked.
368  * If we return TIMER_RETRY, it's necessary to release the timer's lock
369  * and try again.  (This happens when the timer is in the middle of firing.)
370  */
371 static int posix_cpu_timer_del(struct k_itimer *timer)
372 {
373 	int ret = 0;
374 	unsigned long flags;
375 	struct sighand_struct *sighand;
376 	struct task_struct *p = timer->it.cpu.task;
377 
378 	WARN_ON_ONCE(p == NULL);
379 
380 	/*
381 	 * Protect against sighand release/switch in exit/exec and process/
382 	 * thread timer list entry concurrent read/writes.
383 	 */
384 	sighand = lock_task_sighand(p, &flags);
385 	if (unlikely(sighand == NULL)) {
386 		/*
387 		 * We raced with the reaping of the task.
388 		 * The deletion should have cleared us off the list.
389 		 */
390 		WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry));
391 	} else {
392 		if (timer->it.cpu.firing)
393 			ret = TIMER_RETRY;
394 		else
395 			list_del(&timer->it.cpu.entry);
396 
397 		unlock_task_sighand(p, &flags);
398 	}
399 
400 	if (!ret)
401 		put_task_struct(p);
402 
403 	return ret;
404 }
405 
406 static void cleanup_timers_list(struct list_head *head)
407 {
408 	struct cpu_timer_list *timer, *next;
409 
410 	list_for_each_entry_safe(timer, next, head, entry)
411 		list_del_init(&timer->entry);
412 }
413 
414 /*
415  * Clean out CPU timers still ticking when a thread exited.  The task
416  * pointer is cleared, and the expiry time is replaced with the residual
417  * time for later timer_gettime calls to return.
418  * This must be called with the siglock held.
419  */
420 static void cleanup_timers(struct list_head *head)
421 {
422 	cleanup_timers_list(head);
423 	cleanup_timers_list(++head);
424 	cleanup_timers_list(++head);
425 }
426 
427 /*
428  * These are both called with the siglock held, when the current thread
429  * is being reaped.  When the final (leader) thread in the group is reaped,
430  * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
431  */
432 void posix_cpu_timers_exit(struct task_struct *tsk)
433 {
434 	cleanup_timers(tsk->cpu_timers);
435 }
436 void posix_cpu_timers_exit_group(struct task_struct *tsk)
437 {
438 	cleanup_timers(tsk->signal->cpu_timers);
439 }
440 
441 static inline int expires_gt(u64 expires, u64 new_exp)
442 {
443 	return expires == 0 || expires > new_exp;
444 }
445 
446 /*
447  * Insert the timer on the appropriate list before any timers that
448  * expire later.  This must be called with the sighand lock held.
449  */
450 static void arm_timer(struct k_itimer *timer)
451 {
452 	struct task_struct *p = timer->it.cpu.task;
453 	struct list_head *head, *listpos;
454 	struct task_cputime *cputime_expires;
455 	struct cpu_timer_list *const nt = &timer->it.cpu;
456 	struct cpu_timer_list *next;
457 
458 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
459 		head = p->cpu_timers;
460 		cputime_expires = &p->cputime_expires;
461 	} else {
462 		head = p->signal->cpu_timers;
463 		cputime_expires = &p->signal->cputime_expires;
464 	}
465 	head += CPUCLOCK_WHICH(timer->it_clock);
466 
467 	listpos = head;
468 	list_for_each_entry(next, head, entry) {
469 		if (nt->expires < next->expires)
470 			break;
471 		listpos = &next->entry;
472 	}
473 	list_add(&nt->entry, listpos);
474 
475 	if (listpos == head) {
476 		u64 exp = nt->expires;
477 
478 		/*
479 		 * We are the new earliest-expiring POSIX 1.b timer, hence
480 		 * need to update expiration cache. Take into account that
481 		 * for process timers we share expiration cache with itimers
482 		 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
483 		 */
484 
485 		switch (CPUCLOCK_WHICH(timer->it_clock)) {
486 		case CPUCLOCK_PROF:
487 			if (expires_gt(cputime_expires->prof_exp, exp))
488 				cputime_expires->prof_exp = exp;
489 			break;
490 		case CPUCLOCK_VIRT:
491 			if (expires_gt(cputime_expires->virt_exp, exp))
492 				cputime_expires->virt_exp = exp;
493 			break;
494 		case CPUCLOCK_SCHED:
495 			if (expires_gt(cputime_expires->sched_exp, exp))
496 				cputime_expires->sched_exp = exp;
497 			break;
498 		}
499 		if (CPUCLOCK_PERTHREAD(timer->it_clock))
500 			tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
501 		else
502 			tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
503 	}
504 }
505 
506 /*
507  * The timer is locked, fire it and arrange for its reload.
508  */
509 static void cpu_timer_fire(struct k_itimer *timer)
510 {
511 	if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
512 		/*
513 		 * User don't want any signal.
514 		 */
515 		timer->it.cpu.expires = 0;
516 	} else if (unlikely(timer->sigq == NULL)) {
517 		/*
518 		 * This a special case for clock_nanosleep,
519 		 * not a normal timer from sys_timer_create.
520 		 */
521 		wake_up_process(timer->it_process);
522 		timer->it.cpu.expires = 0;
523 	} else if (timer->it.cpu.incr == 0) {
524 		/*
525 		 * One-shot timer.  Clear it as soon as it's fired.
526 		 */
527 		posix_timer_event(timer, 0);
528 		timer->it.cpu.expires = 0;
529 	} else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
530 		/*
531 		 * The signal did not get queued because the signal
532 		 * was ignored, so we won't get any callback to
533 		 * reload the timer.  But we need to keep it
534 		 * ticking in case the signal is deliverable next time.
535 		 */
536 		posix_cpu_timer_rearm(timer);
537 		++timer->it_requeue_pending;
538 	}
539 }
540 
541 /*
542  * Sample a process (thread group) timer for the given group_leader task.
543  * Must be called with task sighand lock held for safe while_each_thread()
544  * traversal.
545  */
546 static int cpu_timer_sample_group(const clockid_t which_clock,
547 				  struct task_struct *p, u64 *sample)
548 {
549 	struct task_cputime cputime;
550 
551 	thread_group_cputimer(p, &cputime);
552 	switch (CPUCLOCK_WHICH(which_clock)) {
553 	default:
554 		return -EINVAL;
555 	case CPUCLOCK_PROF:
556 		*sample = cputime.utime + cputime.stime;
557 		break;
558 	case CPUCLOCK_VIRT:
559 		*sample = cputime.utime;
560 		break;
561 	case CPUCLOCK_SCHED:
562 		*sample = cputime.sum_exec_runtime;
563 		break;
564 	}
565 	return 0;
566 }
567 
568 /*
569  * Guts of sys_timer_settime for CPU timers.
570  * This is called with the timer locked and interrupts disabled.
571  * If we return TIMER_RETRY, it's necessary to release the timer's lock
572  * and try again.  (This happens when the timer is in the middle of firing.)
573  */
574 static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
575 			       struct itimerspec64 *new, struct itimerspec64 *old)
576 {
577 	unsigned long flags;
578 	struct sighand_struct *sighand;
579 	struct task_struct *p = timer->it.cpu.task;
580 	u64 old_expires, new_expires, old_incr, val;
581 	int ret;
582 
583 	WARN_ON_ONCE(p == NULL);
584 
585 	/*
586 	 * Use the to_ktime conversion because that clamps the maximum
587 	 * value to KTIME_MAX and avoid multiplication overflows.
588 	 */
589 	new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value));
590 
591 	/*
592 	 * Protect against sighand release/switch in exit/exec and p->cpu_timers
593 	 * and p->signal->cpu_timers read/write in arm_timer()
594 	 */
595 	sighand = lock_task_sighand(p, &flags);
596 	/*
597 	 * If p has just been reaped, we can no
598 	 * longer get any information about it at all.
599 	 */
600 	if (unlikely(sighand == NULL)) {
601 		return -ESRCH;
602 	}
603 
604 	/*
605 	 * Disarm any old timer after extracting its expiry time.
606 	 */
607 
608 	ret = 0;
609 	old_incr = timer->it.cpu.incr;
610 	old_expires = timer->it.cpu.expires;
611 	if (unlikely(timer->it.cpu.firing)) {
612 		timer->it.cpu.firing = -1;
613 		ret = TIMER_RETRY;
614 	} else
615 		list_del_init(&timer->it.cpu.entry);
616 
617 	/*
618 	 * We need to sample the current value to convert the new
619 	 * value from to relative and absolute, and to convert the
620 	 * old value from absolute to relative.  To set a process
621 	 * timer, we need a sample to balance the thread expiry
622 	 * times (in arm_timer).  With an absolute time, we must
623 	 * check if it's already passed.  In short, we need a sample.
624 	 */
625 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
626 		cpu_clock_sample(timer->it_clock, p, &val);
627 	} else {
628 		cpu_timer_sample_group(timer->it_clock, p, &val);
629 	}
630 
631 	if (old) {
632 		if (old_expires == 0) {
633 			old->it_value.tv_sec = 0;
634 			old->it_value.tv_nsec = 0;
635 		} else {
636 			/*
637 			 * Update the timer in case it has
638 			 * overrun already.  If it has,
639 			 * we'll report it as having overrun
640 			 * and with the next reloaded timer
641 			 * already ticking, though we are
642 			 * swallowing that pending
643 			 * notification here to install the
644 			 * new setting.
645 			 */
646 			bump_cpu_timer(timer, val);
647 			if (val < timer->it.cpu.expires) {
648 				old_expires = timer->it.cpu.expires - val;
649 				old->it_value = ns_to_timespec64(old_expires);
650 			} else {
651 				old->it_value.tv_nsec = 1;
652 				old->it_value.tv_sec = 0;
653 			}
654 		}
655 	}
656 
657 	if (unlikely(ret)) {
658 		/*
659 		 * We are colliding with the timer actually firing.
660 		 * Punt after filling in the timer's old value, and
661 		 * disable this firing since we are already reporting
662 		 * it as an overrun (thanks to bump_cpu_timer above).
663 		 */
664 		unlock_task_sighand(p, &flags);
665 		goto out;
666 	}
667 
668 	if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) {
669 		new_expires += val;
670 	}
671 
672 	/*
673 	 * Install the new expiry time (or zero).
674 	 * For a timer with no notification action, we don't actually
675 	 * arm the timer (we'll just fake it for timer_gettime).
676 	 */
677 	timer->it.cpu.expires = new_expires;
678 	if (new_expires != 0 && val < new_expires) {
679 		arm_timer(timer);
680 	}
681 
682 	unlock_task_sighand(p, &flags);
683 	/*
684 	 * Install the new reload setting, and
685 	 * set up the signal and overrun bookkeeping.
686 	 */
687 	timer->it.cpu.incr = timespec64_to_ns(&new->it_interval);
688 
689 	/*
690 	 * This acts as a modification timestamp for the timer,
691 	 * so any automatic reload attempt will punt on seeing
692 	 * that we have reset the timer manually.
693 	 */
694 	timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
695 		~REQUEUE_PENDING;
696 	timer->it_overrun_last = 0;
697 	timer->it_overrun = -1;
698 
699 	if (new_expires != 0 && !(val < new_expires)) {
700 		/*
701 		 * The designated time already passed, so we notify
702 		 * immediately, even if the thread never runs to
703 		 * accumulate more time on this clock.
704 		 */
705 		cpu_timer_fire(timer);
706 	}
707 
708 	ret = 0;
709  out:
710 	if (old)
711 		old->it_interval = ns_to_timespec64(old_incr);
712 
713 	return ret;
714 }
715 
716 static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
717 {
718 	u64 now;
719 	struct task_struct *p = timer->it.cpu.task;
720 
721 	WARN_ON_ONCE(p == NULL);
722 
723 	/*
724 	 * Easy part: convert the reload time.
725 	 */
726 	itp->it_interval = ns_to_timespec64(timer->it.cpu.incr);
727 
728 	if (!timer->it.cpu.expires)
729 		return;
730 
731 	/*
732 	 * Sample the clock to take the difference with the expiry time.
733 	 */
734 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
735 		cpu_clock_sample(timer->it_clock, p, &now);
736 	} else {
737 		struct sighand_struct *sighand;
738 		unsigned long flags;
739 
740 		/*
741 		 * Protect against sighand release/switch in exit/exec and
742 		 * also make timer sampling safe if it ends up calling
743 		 * thread_group_cputime().
744 		 */
745 		sighand = lock_task_sighand(p, &flags);
746 		if (unlikely(sighand == NULL)) {
747 			/*
748 			 * The process has been reaped.
749 			 * We can't even collect a sample any more.
750 			 * Call the timer disarmed, nothing else to do.
751 			 */
752 			timer->it.cpu.expires = 0;
753 			return;
754 		} else {
755 			cpu_timer_sample_group(timer->it_clock, p, &now);
756 			unlock_task_sighand(p, &flags);
757 		}
758 	}
759 
760 	if (now < timer->it.cpu.expires) {
761 		itp->it_value = ns_to_timespec64(timer->it.cpu.expires - now);
762 	} else {
763 		/*
764 		 * The timer should have expired already, but the firing
765 		 * hasn't taken place yet.  Say it's just about to expire.
766 		 */
767 		itp->it_value.tv_nsec = 1;
768 		itp->it_value.tv_sec = 0;
769 	}
770 }
771 
772 static unsigned long long
773 check_timers_list(struct list_head *timers,
774 		  struct list_head *firing,
775 		  unsigned long long curr)
776 {
777 	int maxfire = 20;
778 
779 	while (!list_empty(timers)) {
780 		struct cpu_timer_list *t;
781 
782 		t = list_first_entry(timers, struct cpu_timer_list, entry);
783 
784 		if (!--maxfire || curr < t->expires)
785 			return t->expires;
786 
787 		t->firing = 1;
788 		list_move_tail(&t->entry, firing);
789 	}
790 
791 	return 0;
792 }
793 
794 static inline void check_dl_overrun(struct task_struct *tsk)
795 {
796 	if (tsk->dl.dl_overrun) {
797 		tsk->dl.dl_overrun = 0;
798 		__group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
799 	}
800 }
801 
802 /*
803  * Check for any per-thread CPU timers that have fired and move them off
804  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
805  * tsk->it_*_expires values to reflect the remaining thread CPU timers.
806  */
807 static void check_thread_timers(struct task_struct *tsk,
808 				struct list_head *firing)
809 {
810 	struct list_head *timers = tsk->cpu_timers;
811 	struct task_cputime *tsk_expires = &tsk->cputime_expires;
812 	u64 expires;
813 	unsigned long soft;
814 
815 	if (dl_task(tsk))
816 		check_dl_overrun(tsk);
817 
818 	/*
819 	 * If cputime_expires is zero, then there are no active
820 	 * per thread CPU timers.
821 	 */
822 	if (task_cputime_zero(&tsk->cputime_expires))
823 		return;
824 
825 	expires = check_timers_list(timers, firing, prof_ticks(tsk));
826 	tsk_expires->prof_exp = expires;
827 
828 	expires = check_timers_list(++timers, firing, virt_ticks(tsk));
829 	tsk_expires->virt_exp = expires;
830 
831 	tsk_expires->sched_exp = check_timers_list(++timers, firing,
832 						   tsk->se.sum_exec_runtime);
833 
834 	/*
835 	 * Check for the special case thread timers.
836 	 */
837 	soft = task_rlimit(tsk, RLIMIT_RTTIME);
838 	if (soft != RLIM_INFINITY) {
839 		unsigned long hard = task_rlimit_max(tsk, RLIMIT_RTTIME);
840 
841 		if (hard != RLIM_INFINITY &&
842 		    tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
843 			/*
844 			 * At the hard limit, we just die.
845 			 * No need to calculate anything else now.
846 			 */
847 			if (print_fatal_signals) {
848 				pr_info("CPU Watchdog Timeout (hard): %s[%d]\n",
849 					tsk->comm, task_pid_nr(tsk));
850 			}
851 			__group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
852 			return;
853 		}
854 		if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
855 			/*
856 			 * At the soft limit, send a SIGXCPU every second.
857 			 */
858 			if (soft < hard) {
859 				soft += USEC_PER_SEC;
860 				tsk->signal->rlim[RLIMIT_RTTIME].rlim_cur =
861 					soft;
862 			}
863 			if (print_fatal_signals) {
864 				pr_info("RT Watchdog Timeout (soft): %s[%d]\n",
865 					tsk->comm, task_pid_nr(tsk));
866 			}
867 			__group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
868 		}
869 	}
870 	if (task_cputime_zero(tsk_expires))
871 		tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
872 }
873 
874 static inline void stop_process_timers(struct signal_struct *sig)
875 {
876 	struct thread_group_cputimer *cputimer = &sig->cputimer;
877 
878 	/* Turn off cputimer->running. This is done without locking. */
879 	WRITE_ONCE(cputimer->running, false);
880 	tick_dep_clear_signal(sig, TICK_DEP_BIT_POSIX_TIMER);
881 }
882 
883 static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
884 			     u64 *expires, u64 cur_time, int signo)
885 {
886 	if (!it->expires)
887 		return;
888 
889 	if (cur_time >= it->expires) {
890 		if (it->incr)
891 			it->expires += it->incr;
892 		else
893 			it->expires = 0;
894 
895 		trace_itimer_expire(signo == SIGPROF ?
896 				    ITIMER_PROF : ITIMER_VIRTUAL,
897 				    tsk->signal->leader_pid, cur_time);
898 		__group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
899 	}
900 
901 	if (it->expires && (!*expires || it->expires < *expires))
902 		*expires = it->expires;
903 }
904 
905 /*
906  * Check for any per-thread CPU timers that have fired and move them
907  * off the tsk->*_timers list onto the firing list.  Per-thread timers
908  * have already been taken off.
909  */
910 static void check_process_timers(struct task_struct *tsk,
911 				 struct list_head *firing)
912 {
913 	struct signal_struct *const sig = tsk->signal;
914 	u64 utime, ptime, virt_expires, prof_expires;
915 	u64 sum_sched_runtime, sched_expires;
916 	struct list_head *timers = sig->cpu_timers;
917 	struct task_cputime cputime;
918 	unsigned long soft;
919 
920 	if (dl_task(tsk))
921 		check_dl_overrun(tsk);
922 
923 	/*
924 	 * If cputimer is not running, then there are no active
925 	 * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU).
926 	 */
927 	if (!READ_ONCE(tsk->signal->cputimer.running))
928 		return;
929 
930         /*
931 	 * Signify that a thread is checking for process timers.
932 	 * Write access to this field is protected by the sighand lock.
933 	 */
934 	sig->cputimer.checking_timer = true;
935 
936 	/*
937 	 * Collect the current process totals.
938 	 */
939 	thread_group_cputimer(tsk, &cputime);
940 	utime = cputime.utime;
941 	ptime = utime + cputime.stime;
942 	sum_sched_runtime = cputime.sum_exec_runtime;
943 
944 	prof_expires = check_timers_list(timers, firing, ptime);
945 	virt_expires = check_timers_list(++timers, firing, utime);
946 	sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);
947 
948 	/*
949 	 * Check for the special case process timers.
950 	 */
951 	check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
952 			 SIGPROF);
953 	check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
954 			 SIGVTALRM);
955 	soft = task_rlimit(tsk, RLIMIT_CPU);
956 	if (soft != RLIM_INFINITY) {
957 		unsigned long psecs = div_u64(ptime, NSEC_PER_SEC);
958 		unsigned long hard = task_rlimit_max(tsk, RLIMIT_CPU);
959 		u64 x;
960 		if (psecs >= hard) {
961 			/*
962 			 * At the hard limit, we just die.
963 			 * No need to calculate anything else now.
964 			 */
965 			if (print_fatal_signals) {
966 				pr_info("RT Watchdog Timeout (hard): %s[%d]\n",
967 					tsk->comm, task_pid_nr(tsk));
968 			}
969 			__group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
970 			return;
971 		}
972 		if (psecs >= soft) {
973 			/*
974 			 * At the soft limit, send a SIGXCPU every second.
975 			 */
976 			if (print_fatal_signals) {
977 				pr_info("CPU Watchdog Timeout (soft): %s[%d]\n",
978 					tsk->comm, task_pid_nr(tsk));
979 			}
980 			__group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
981 			if (soft < hard) {
982 				soft++;
983 				sig->rlim[RLIMIT_CPU].rlim_cur = soft;
984 			}
985 		}
986 		x = soft * NSEC_PER_SEC;
987 		if (!prof_expires || x < prof_expires)
988 			prof_expires = x;
989 	}
990 
991 	sig->cputime_expires.prof_exp = prof_expires;
992 	sig->cputime_expires.virt_exp = virt_expires;
993 	sig->cputime_expires.sched_exp = sched_expires;
994 	if (task_cputime_zero(&sig->cputime_expires))
995 		stop_process_timers(sig);
996 
997 	sig->cputimer.checking_timer = false;
998 }
999 
1000 /*
1001  * This is called from the signal code (via posixtimer_rearm)
1002  * when the last timer signal was delivered and we have to reload the timer.
1003  */
1004 static void posix_cpu_timer_rearm(struct k_itimer *timer)
1005 {
1006 	struct sighand_struct *sighand;
1007 	unsigned long flags;
1008 	struct task_struct *p = timer->it.cpu.task;
1009 	u64 now;
1010 
1011 	WARN_ON_ONCE(p == NULL);
1012 
1013 	/*
1014 	 * Fetch the current sample and update the timer's expiry time.
1015 	 */
1016 	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1017 		cpu_clock_sample(timer->it_clock, p, &now);
1018 		bump_cpu_timer(timer, now);
1019 		if (unlikely(p->exit_state))
1020 			return;
1021 
1022 		/* Protect timer list r/w in arm_timer() */
1023 		sighand = lock_task_sighand(p, &flags);
1024 		if (!sighand)
1025 			return;
1026 	} else {
1027 		/*
1028 		 * Protect arm_timer() and timer sampling in case of call to
1029 		 * thread_group_cputime().
1030 		 */
1031 		sighand = lock_task_sighand(p, &flags);
1032 		if (unlikely(sighand == NULL)) {
1033 			/*
1034 			 * The process has been reaped.
1035 			 * We can't even collect a sample any more.
1036 			 */
1037 			timer->it.cpu.expires = 0;
1038 			return;
1039 		} else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1040 			/* If the process is dying, no need to rearm */
1041 			goto unlock;
1042 		}
1043 		cpu_timer_sample_group(timer->it_clock, p, &now);
1044 		bump_cpu_timer(timer, now);
1045 		/* Leave the sighand locked for the call below.  */
1046 	}
1047 
1048 	/*
1049 	 * Now re-arm for the new expiry time.
1050 	 */
1051 	arm_timer(timer);
1052 unlock:
1053 	unlock_task_sighand(p, &flags);
1054 }
1055 
1056 /**
1057  * task_cputime_expired - Compare two task_cputime entities.
1058  *
1059  * @sample:	The task_cputime structure to be checked for expiration.
1060  * @expires:	Expiration times, against which @sample will be checked.
1061  *
1062  * Checks @sample against @expires to see if any field of @sample has expired.
1063  * Returns true if any field of the former is greater than the corresponding
1064  * field of the latter if the latter field is set.  Otherwise returns false.
1065  */
1066 static inline int task_cputime_expired(const struct task_cputime *sample,
1067 					const struct task_cputime *expires)
1068 {
1069 	if (expires->utime && sample->utime >= expires->utime)
1070 		return 1;
1071 	if (expires->stime && sample->utime + sample->stime >= expires->stime)
1072 		return 1;
1073 	if (expires->sum_exec_runtime != 0 &&
1074 	    sample->sum_exec_runtime >= expires->sum_exec_runtime)
1075 		return 1;
1076 	return 0;
1077 }
1078 
1079 /**
1080  * fastpath_timer_check - POSIX CPU timers fast path.
1081  *
1082  * @tsk:	The task (thread) being checked.
1083  *
1084  * Check the task and thread group timers.  If both are zero (there are no
1085  * timers set) return false.  Otherwise snapshot the task and thread group
1086  * timers and compare them with the corresponding expiration times.  Return
1087  * true if a timer has expired, else return false.
1088  */
1089 static inline int fastpath_timer_check(struct task_struct *tsk)
1090 {
1091 	struct signal_struct *sig;
1092 
1093 	if (!task_cputime_zero(&tsk->cputime_expires)) {
1094 		struct task_cputime task_sample;
1095 
1096 		task_cputime(tsk, &task_sample.utime, &task_sample.stime);
1097 		task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
1098 		if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1099 			return 1;
1100 	}
1101 
1102 	sig = tsk->signal;
1103 	/*
1104 	 * Check if thread group timers expired when the cputimer is
1105 	 * running and no other thread in the group is already checking
1106 	 * for thread group cputimers. These fields are read without the
1107 	 * sighand lock. However, this is fine because this is meant to
1108 	 * be a fastpath heuristic to determine whether we should try to
1109 	 * acquire the sighand lock to check/handle timers.
1110 	 *
1111 	 * In the worst case scenario, if 'running' or 'checking_timer' gets
1112 	 * set but the current thread doesn't see the change yet, we'll wait
1113 	 * until the next thread in the group gets a scheduler interrupt to
1114 	 * handle the timer. This isn't an issue in practice because these
1115 	 * types of delays with signals actually getting sent are expected.
1116 	 */
1117 	if (READ_ONCE(sig->cputimer.running) &&
1118 	    !READ_ONCE(sig->cputimer.checking_timer)) {
1119 		struct task_cputime group_sample;
1120 
1121 		sample_cputime_atomic(&group_sample, &sig->cputimer.cputime_atomic);
1122 
1123 		if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1124 			return 1;
1125 	}
1126 
1127 	if (dl_task(tsk) && tsk->dl.dl_overrun)
1128 		return 1;
1129 
1130 	return 0;
1131 }
1132 
1133 /*
1134  * This is called from the timer interrupt handler.  The irq handler has
1135  * already updated our counts.  We need to check if any timers fire now.
1136  * Interrupts are disabled.
1137  */
1138 void run_posix_cpu_timers(struct task_struct *tsk)
1139 {
1140 	LIST_HEAD(firing);
1141 	struct k_itimer *timer, *next;
1142 	unsigned long flags;
1143 
1144 	lockdep_assert_irqs_disabled();
1145 
1146 	/*
1147 	 * The fast path checks that there are no expired thread or thread
1148 	 * group timers.  If that's so, just return.
1149 	 */
1150 	if (!fastpath_timer_check(tsk))
1151 		return;
1152 
1153 	if (!lock_task_sighand(tsk, &flags))
1154 		return;
1155 	/*
1156 	 * Here we take off tsk->signal->cpu_timers[N] and
1157 	 * tsk->cpu_timers[N] all the timers that are firing, and
1158 	 * put them on the firing list.
1159 	 */
1160 	check_thread_timers(tsk, &firing);
1161 
1162 	check_process_timers(tsk, &firing);
1163 
1164 	/*
1165 	 * We must release these locks before taking any timer's lock.
1166 	 * There is a potential race with timer deletion here, as the
1167 	 * siglock now protects our private firing list.  We have set
1168 	 * the firing flag in each timer, so that a deletion attempt
1169 	 * that gets the timer lock before we do will give it up and
1170 	 * spin until we've taken care of that timer below.
1171 	 */
1172 	unlock_task_sighand(tsk, &flags);
1173 
1174 	/*
1175 	 * Now that all the timers on our list have the firing flag,
1176 	 * no one will touch their list entries but us.  We'll take
1177 	 * each timer's lock before clearing its firing flag, so no
1178 	 * timer call will interfere.
1179 	 */
1180 	list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1181 		int cpu_firing;
1182 
1183 		spin_lock(&timer->it_lock);
1184 		list_del_init(&timer->it.cpu.entry);
1185 		cpu_firing = timer->it.cpu.firing;
1186 		timer->it.cpu.firing = 0;
1187 		/*
1188 		 * The firing flag is -1 if we collided with a reset
1189 		 * of the timer, which already reported this
1190 		 * almost-firing as an overrun.  So don't generate an event.
1191 		 */
1192 		if (likely(cpu_firing >= 0))
1193 			cpu_timer_fire(timer);
1194 		spin_unlock(&timer->it_lock);
1195 	}
1196 }
1197 
1198 /*
1199  * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1200  * The tsk->sighand->siglock must be held by the caller.
1201  */
1202 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1203 			   u64 *newval, u64 *oldval)
1204 {
1205 	u64 now;
1206 	int ret;
1207 
1208 	WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED);
1209 	ret = cpu_timer_sample_group(clock_idx, tsk, &now);
1210 
1211 	if (oldval && ret != -EINVAL) {
1212 		/*
1213 		 * We are setting itimer. The *oldval is absolute and we update
1214 		 * it to be relative, *newval argument is relative and we update
1215 		 * it to be absolute.
1216 		 */
1217 		if (*oldval) {
1218 			if (*oldval <= now) {
1219 				/* Just about to fire. */
1220 				*oldval = TICK_NSEC;
1221 			} else {
1222 				*oldval -= now;
1223 			}
1224 		}
1225 
1226 		if (!*newval)
1227 			return;
1228 		*newval += now;
1229 	}
1230 
1231 	/*
1232 	 * Update expiration cache if we are the earliest timer, or eventually
1233 	 * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1234 	 */
1235 	switch (clock_idx) {
1236 	case CPUCLOCK_PROF:
1237 		if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1238 			tsk->signal->cputime_expires.prof_exp = *newval;
1239 		break;
1240 	case CPUCLOCK_VIRT:
1241 		if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1242 			tsk->signal->cputime_expires.virt_exp = *newval;
1243 		break;
1244 	}
1245 
1246 	tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER);
1247 }
1248 
1249 static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1250 			    const struct timespec64 *rqtp)
1251 {
1252 	struct itimerspec64 it;
1253 	struct k_itimer timer;
1254 	u64 expires;
1255 	int error;
1256 
1257 	/*
1258 	 * Set up a temporary timer and then wait for it to go off.
1259 	 */
1260 	memset(&timer, 0, sizeof timer);
1261 	spin_lock_init(&timer.it_lock);
1262 	timer.it_clock = which_clock;
1263 	timer.it_overrun = -1;
1264 	error = posix_cpu_timer_create(&timer);
1265 	timer.it_process = current;
1266 	if (!error) {
1267 		static struct itimerspec64 zero_it;
1268 		struct restart_block *restart;
1269 
1270 		memset(&it, 0, sizeof(it));
1271 		it.it_value = *rqtp;
1272 
1273 		spin_lock_irq(&timer.it_lock);
1274 		error = posix_cpu_timer_set(&timer, flags, &it, NULL);
1275 		if (error) {
1276 			spin_unlock_irq(&timer.it_lock);
1277 			return error;
1278 		}
1279 
1280 		while (!signal_pending(current)) {
1281 			if (timer.it.cpu.expires == 0) {
1282 				/*
1283 				 * Our timer fired and was reset, below
1284 				 * deletion can not fail.
1285 				 */
1286 				posix_cpu_timer_del(&timer);
1287 				spin_unlock_irq(&timer.it_lock);
1288 				return 0;
1289 			}
1290 
1291 			/*
1292 			 * Block until cpu_timer_fire (or a signal) wakes us.
1293 			 */
1294 			__set_current_state(TASK_INTERRUPTIBLE);
1295 			spin_unlock_irq(&timer.it_lock);
1296 			schedule();
1297 			spin_lock_irq(&timer.it_lock);
1298 		}
1299 
1300 		/*
1301 		 * We were interrupted by a signal.
1302 		 */
1303 		expires = timer.it.cpu.expires;
1304 		error = posix_cpu_timer_set(&timer, 0, &zero_it, &it);
1305 		if (!error) {
1306 			/*
1307 			 * Timer is now unarmed, deletion can not fail.
1308 			 */
1309 			posix_cpu_timer_del(&timer);
1310 		}
1311 		spin_unlock_irq(&timer.it_lock);
1312 
1313 		while (error == TIMER_RETRY) {
1314 			/*
1315 			 * We need to handle case when timer was or is in the
1316 			 * middle of firing. In other cases we already freed
1317 			 * resources.
1318 			 */
1319 			spin_lock_irq(&timer.it_lock);
1320 			error = posix_cpu_timer_del(&timer);
1321 			spin_unlock_irq(&timer.it_lock);
1322 		}
1323 
1324 		if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
1325 			/*
1326 			 * It actually did fire already.
1327 			 */
1328 			return 0;
1329 		}
1330 
1331 		error = -ERESTART_RESTARTBLOCK;
1332 		/*
1333 		 * Report back to the user the time still remaining.
1334 		 */
1335 		restart = &current->restart_block;
1336 		restart->nanosleep.expires = expires;
1337 		if (restart->nanosleep.type != TT_NONE)
1338 			error = nanosleep_copyout(restart, &it.it_value);
1339 	}
1340 
1341 	return error;
1342 }
1343 
1344 static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1345 
1346 static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1347 			    const struct timespec64 *rqtp)
1348 {
1349 	struct restart_block *restart_block = &current->restart_block;
1350 	int error;
1351 
1352 	/*
1353 	 * Diagnose required errors first.
1354 	 */
1355 	if (CPUCLOCK_PERTHREAD(which_clock) &&
1356 	    (CPUCLOCK_PID(which_clock) == 0 ||
1357 	     CPUCLOCK_PID(which_clock) == task_pid_vnr(current)))
1358 		return -EINVAL;
1359 
1360 	error = do_cpu_nanosleep(which_clock, flags, rqtp);
1361 
1362 	if (error == -ERESTART_RESTARTBLOCK) {
1363 
1364 		if (flags & TIMER_ABSTIME)
1365 			return -ERESTARTNOHAND;
1366 
1367 		restart_block->fn = posix_cpu_nsleep_restart;
1368 		restart_block->nanosleep.clockid = which_clock;
1369 	}
1370 	return error;
1371 }
1372 
1373 static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1374 {
1375 	clockid_t which_clock = restart_block->nanosleep.clockid;
1376 	struct timespec64 t;
1377 
1378 	t = ns_to_timespec64(restart_block->nanosleep.expires);
1379 
1380 	return do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t);
1381 }
1382 
1383 #define PROCESS_CLOCK	make_process_cpuclock(0, CPUCLOCK_SCHED)
1384 #define THREAD_CLOCK	make_thread_cpuclock(0, CPUCLOCK_SCHED)
1385 
1386 static int process_cpu_clock_getres(const clockid_t which_clock,
1387 				    struct timespec64 *tp)
1388 {
1389 	return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1390 }
1391 static int process_cpu_clock_get(const clockid_t which_clock,
1392 				 struct timespec64 *tp)
1393 {
1394 	return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1395 }
1396 static int process_cpu_timer_create(struct k_itimer *timer)
1397 {
1398 	timer->it_clock = PROCESS_CLOCK;
1399 	return posix_cpu_timer_create(timer);
1400 }
1401 static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1402 			      const struct timespec64 *rqtp)
1403 {
1404 	return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp);
1405 }
1406 static int thread_cpu_clock_getres(const clockid_t which_clock,
1407 				   struct timespec64 *tp)
1408 {
1409 	return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1410 }
1411 static int thread_cpu_clock_get(const clockid_t which_clock,
1412 				struct timespec64 *tp)
1413 {
1414 	return posix_cpu_clock_get(THREAD_CLOCK, tp);
1415 }
1416 static int thread_cpu_timer_create(struct k_itimer *timer)
1417 {
1418 	timer->it_clock = THREAD_CLOCK;
1419 	return posix_cpu_timer_create(timer);
1420 }
1421 
1422 const struct k_clock clock_posix_cpu = {
1423 	.clock_getres	= posix_cpu_clock_getres,
1424 	.clock_set	= posix_cpu_clock_set,
1425 	.clock_get	= posix_cpu_clock_get,
1426 	.timer_create	= posix_cpu_timer_create,
1427 	.nsleep		= posix_cpu_nsleep,
1428 	.timer_set	= posix_cpu_timer_set,
1429 	.timer_del	= posix_cpu_timer_del,
1430 	.timer_get	= posix_cpu_timer_get,
1431 	.timer_rearm	= posix_cpu_timer_rearm,
1432 };
1433 
1434 const struct k_clock clock_process = {
1435 	.clock_getres	= process_cpu_clock_getres,
1436 	.clock_get	= process_cpu_clock_get,
1437 	.timer_create	= process_cpu_timer_create,
1438 	.nsleep		= process_cpu_nsleep,
1439 };
1440 
1441 const struct k_clock clock_thread = {
1442 	.clock_getres	= thread_cpu_clock_getres,
1443 	.clock_get	= thread_cpu_clock_get,
1444 	.timer_create	= thread_cpu_timer_create,
1445 };
1446