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1/*
2 * Implement CPU time clocks for the POSIX clock interface.
3 */
4
5#include <linux/sched.h>
6#include <linux/posix-timers.h>
7#include <linux/errno.h>
8#include <linux/math64.h>
9#include <asm/uaccess.h>
10#include <linux/kernel_stat.h>
11#include <trace/events/timer.h>
12#include <linux/random.h>
13#include <linux/tick.h>
14#include <linux/workqueue.h>
15
16/*
17 * Called after updating RLIMIT_CPU to run cpu timer and update
18 * tsk->signal->cputime_expires expiration cache if necessary. Needs
19 * siglock protection since other code may update expiration cache as
20 * well.
21 */
22void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
23{
24 cputime_t cputime = secs_to_cputime(rlim_new);
25
26 spin_lock_irq(&task->sighand->siglock);
27 set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
28 spin_unlock_irq(&task->sighand->siglock);
29}
30
31static int check_clock(const clockid_t which_clock)
32{
33 int error = 0;
34 struct task_struct *p;
35 const pid_t pid = CPUCLOCK_PID(which_clock);
36
37 if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
38 return -EINVAL;
39
40 if (pid == 0)
41 return 0;
42
43 rcu_read_lock();
44 p = find_task_by_vpid(pid);
45 if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
46 same_thread_group(p, current) : has_group_leader_pid(p))) {
47 error = -EINVAL;
48 }
49 rcu_read_unlock();
50
51 return error;
52}
53
54static inline unsigned long long
55timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
56{
57 unsigned long long ret;
58
59 ret = 0; /* high half always zero when .cpu used */
60 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
61 ret = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
62 } else {
63 ret = cputime_to_expires(timespec_to_cputime(tp));
64 }
65 return ret;
66}
67
68static void sample_to_timespec(const clockid_t which_clock,
69 unsigned long long expires,
70 struct timespec *tp)
71{
72 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED)
73 *tp = ns_to_timespec(expires);
74 else
75 cputime_to_timespec((__force cputime_t)expires, tp);
76}
77
78/*
79 * Update expiry time from increment, and increase overrun count,
80 * given the current clock sample.
81 */
82static void bump_cpu_timer(struct k_itimer *timer,
83 unsigned long long now)
84{
85 int i;
86 unsigned long long delta, incr;
87
88 if (timer->it.cpu.incr == 0)
89 return;
90
91 if (now < timer->it.cpu.expires)
92 return;
93
94 incr = timer->it.cpu.incr;
95 delta = now + incr - timer->it.cpu.expires;
96
97 /* Don't use (incr*2 < delta), incr*2 might overflow. */
98 for (i = 0; incr < delta - incr; i++)
99 incr = incr << 1;
100
101 for (; i >= 0; incr >>= 1, i--) {
102 if (delta < incr)
103 continue;
104
105 timer->it.cpu.expires += incr;
106 timer->it_overrun += 1 << i;
107 delta -= incr;
108 }
109}
110
111/**
112 * task_cputime_zero - Check a task_cputime struct for all zero fields.
113 *
114 * @cputime: The struct to compare.
115 *
116 * Checks @cputime to see if all fields are zero. Returns true if all fields
117 * are zero, false if any field is nonzero.
118 */
119static inline int task_cputime_zero(const struct task_cputime *cputime)
120{
121 if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
122 return 1;
123 return 0;
124}
125
126static inline unsigned long long prof_ticks(struct task_struct *p)
127{
128 cputime_t utime, stime;
129
130 task_cputime(p, &utime, &stime);
131
132 return cputime_to_expires(utime + stime);
133}
134static inline unsigned long long virt_ticks(struct task_struct *p)
135{
136 cputime_t utime;
137
138 task_cputime(p, &utime, NULL);
139
140 return cputime_to_expires(utime);
141}
142
143static int
144posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
145{
146 int error = check_clock(which_clock);
147 if (!error) {
148 tp->tv_sec = 0;
149 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
150 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
151 /*
152 * If sched_clock is using a cycle counter, we
153 * don't have any idea of its true resolution
154 * exported, but it is much more than 1s/HZ.
155 */
156 tp->tv_nsec = 1;
157 }
158 }
159 return error;
160}
161
162static int
163posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
164{
165 /*
166 * You can never reset a CPU clock, but we check for other errors
167 * in the call before failing with EPERM.
168 */
169 int error = check_clock(which_clock);
170 if (error == 0) {
171 error = -EPERM;
172 }
173 return error;
174}
175
176
177/*
178 * Sample a per-thread clock for the given task.
179 */
180static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
181 unsigned long long *sample)
182{
183 switch (CPUCLOCK_WHICH(which_clock)) {
184 default:
185 return -EINVAL;
186 case CPUCLOCK_PROF:
187 *sample = prof_ticks(p);
188 break;
189 case CPUCLOCK_VIRT:
190 *sample = virt_ticks(p);
191 break;
192 case CPUCLOCK_SCHED:
193 *sample = task_sched_runtime(p);
194 break;
195 }
196 return 0;
197}
198
199/*
200 * Set cputime to sum_cputime if sum_cputime > cputime. Use cmpxchg
201 * to avoid race conditions with concurrent updates to cputime.
202 */
203static inline void __update_gt_cputime(atomic64_t *cputime, u64 sum_cputime)
204{
205 u64 curr_cputime;
206retry:
207 curr_cputime = atomic64_read(cputime);
208 if (sum_cputime > curr_cputime) {
209 if (atomic64_cmpxchg(cputime, curr_cputime, sum_cputime) != curr_cputime)
210 goto retry;
211 }
212}
213
214static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic, struct task_cputime *sum)
215{
216 __update_gt_cputime(&cputime_atomic->utime, sum->utime);
217 __update_gt_cputime(&cputime_atomic->stime, sum->stime);
218 __update_gt_cputime(&cputime_atomic->sum_exec_runtime, sum->sum_exec_runtime);
219}
220
221/* Sample task_cputime_atomic values in "atomic_timers", store results in "times". */
222static inline void sample_cputime_atomic(struct task_cputime *times,
223 struct task_cputime_atomic *atomic_times)
224{
225 times->utime = atomic64_read(&atomic_times->utime);
226 times->stime = atomic64_read(&atomic_times->stime);
227 times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime);
228}
229
230void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
231{
232 struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
233 struct task_cputime sum;
234
235 /* Check if cputimer isn't running. This is accessed without locking. */
236 if (!READ_ONCE(cputimer->running)) {
237 /*
238 * The POSIX timer interface allows for absolute time expiry
239 * values through the TIMER_ABSTIME flag, therefore we have
240 * to synchronize the timer to the clock every time we start it.
241 */
242 thread_group_cputime(tsk, &sum);
243 update_gt_cputime(&cputimer->cputime_atomic, &sum);
244
245 /*
246 * We're setting cputimer->running without a lock. Ensure
247 * this only gets written to in one operation. We set
248 * running after update_gt_cputime() as a small optimization,
249 * but barriers are not required because update_gt_cputime()
250 * can handle concurrent updates.
251 */
252 WRITE_ONCE(cputimer->running, true);
253 }
254 sample_cputime_atomic(times, &cputimer->cputime_atomic);
255}
256
257/*
258 * Sample a process (thread group) clock for the given group_leader task.
259 * Must be called with task sighand lock held for safe while_each_thread()
260 * traversal.
261 */
262static int cpu_clock_sample_group(const clockid_t which_clock,
263 struct task_struct *p,
264 unsigned long long *sample)
265{
266 struct task_cputime cputime;
267
268 switch (CPUCLOCK_WHICH(which_clock)) {
269 default:
270 return -EINVAL;
271 case CPUCLOCK_PROF:
272 thread_group_cputime(p, &cputime);
273 *sample = cputime_to_expires(cputime.utime + cputime.stime);
274 break;
275 case CPUCLOCK_VIRT:
276 thread_group_cputime(p, &cputime);
277 *sample = cputime_to_expires(cputime.utime);
278 break;
279 case CPUCLOCK_SCHED:
280 thread_group_cputime(p, &cputime);
281 *sample = cputime.sum_exec_runtime;
282 break;
283 }
284 return 0;
285}
286
287static int posix_cpu_clock_get_task(struct task_struct *tsk,
288 const clockid_t which_clock,
289 struct timespec *tp)
290{
291 int err = -EINVAL;
292 unsigned long long rtn;
293
294 if (CPUCLOCK_PERTHREAD(which_clock)) {
295 if (same_thread_group(tsk, current))
296 err = cpu_clock_sample(which_clock, tsk, &rtn);
297 } else {
298 if (tsk == current || thread_group_leader(tsk))
299 err = cpu_clock_sample_group(which_clock, tsk, &rtn);
300 }
301
302 if (!err)
303 sample_to_timespec(which_clock, rtn, tp);
304
305 return err;
306}
307
308
309static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
310{
311 const pid_t pid = CPUCLOCK_PID(which_clock);
312 int err = -EINVAL;
313
314 if (pid == 0) {
315 /*
316 * Special case constant value for our own clocks.
317 * We don't have to do any lookup to find ourselves.
318 */
319 err = posix_cpu_clock_get_task(current, which_clock, tp);
320 } else {
321 /*
322 * Find the given PID, and validate that the caller
323 * should be able to see it.
324 */
325 struct task_struct *p;
326 rcu_read_lock();
327 p = find_task_by_vpid(pid);
328 if (p)
329 err = posix_cpu_clock_get_task(p, which_clock, tp);
330 rcu_read_unlock();
331 }
332
333 return err;
334}
335
336/*
337 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
338 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
339 * new timer already all-zeros initialized.
340 */
341static int posix_cpu_timer_create(struct k_itimer *new_timer)
342{
343 int ret = 0;
344 const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
345 struct task_struct *p;
346
347 if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
348 return -EINVAL;
349
350 INIT_LIST_HEAD(&new_timer->it.cpu.entry);
351
352 rcu_read_lock();
353 if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
354 if (pid == 0) {
355 p = current;
356 } else {
357 p = find_task_by_vpid(pid);
358 if (p && !same_thread_group(p, current))
359 p = NULL;
360 }
361 } else {
362 if (pid == 0) {
363 p = current->group_leader;
364 } else {
365 p = find_task_by_vpid(pid);
366 if (p && !has_group_leader_pid(p))
367 p = NULL;
368 }
369 }
370 new_timer->it.cpu.task = p;
371 if (p) {
372 get_task_struct(p);
373 } else {
374 ret = -EINVAL;
375 }
376 rcu_read_unlock();
377
378 return ret;
379}
380
381/*
382 * Clean up a CPU-clock timer that is about to be destroyed.
383 * This is called from timer deletion with the timer already locked.
384 * If we return TIMER_RETRY, it's necessary to release the timer's lock
385 * and try again. (This happens when the timer is in the middle of firing.)
386 */
387static int posix_cpu_timer_del(struct k_itimer *timer)
388{
389 int ret = 0;
390 unsigned long flags;
391 struct sighand_struct *sighand;
392 struct task_struct *p = timer->it.cpu.task;
393
394 WARN_ON_ONCE(p == NULL);
395
396 /*
397 * Protect against sighand release/switch in exit/exec and process/
398 * thread timer list entry concurrent read/writes.
399 */
400 sighand = lock_task_sighand(p, &flags);
401 if (unlikely(sighand == NULL)) {
402 /*
403 * We raced with the reaping of the task.
404 * The deletion should have cleared us off the list.
405 */
406 WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry));
407 } else {
408 if (timer->it.cpu.firing)
409 ret = TIMER_RETRY;
410 else
411 list_del(&timer->it.cpu.entry);
412
413 unlock_task_sighand(p, &flags);
414 }
415
416 if (!ret)
417 put_task_struct(p);
418
419 return ret;
420}
421
422static void cleanup_timers_list(struct list_head *head)
423{
424 struct cpu_timer_list *timer, *next;
425
426 list_for_each_entry_safe(timer, next, head, entry)
427 list_del_init(&timer->entry);
428}
429
430/*
431 * Clean out CPU timers still ticking when a thread exited. The task
432 * pointer is cleared, and the expiry time is replaced with the residual
433 * time for later timer_gettime calls to return.
434 * This must be called with the siglock held.
435 */
436static void cleanup_timers(struct list_head *head)
437{
438 cleanup_timers_list(head);
439 cleanup_timers_list(++head);
440 cleanup_timers_list(++head);
441}
442
443/*
444 * These are both called with the siglock held, when the current thread
445 * is being reaped. When the final (leader) thread in the group is reaped,
446 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
447 */
448void posix_cpu_timers_exit(struct task_struct *tsk)
449{
450 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
451 sizeof(unsigned long long));
452 cleanup_timers(tsk->cpu_timers);
453
454}
455void posix_cpu_timers_exit_group(struct task_struct *tsk)
456{
457 cleanup_timers(tsk->signal->cpu_timers);
458}
459
460static inline int expires_gt(cputime_t expires, cputime_t new_exp)
461{
462 return expires == 0 || expires > new_exp;
463}
464
465/*
466 * Insert the timer on the appropriate list before any timers that
467 * expire later. This must be called with the sighand lock held.
468 */
469static void arm_timer(struct k_itimer *timer)
470{
471 struct task_struct *p = timer->it.cpu.task;
472 struct list_head *head, *listpos;
473 struct task_cputime *cputime_expires;
474 struct cpu_timer_list *const nt = &timer->it.cpu;
475 struct cpu_timer_list *next;
476
477 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
478 head = p->cpu_timers;
479 cputime_expires = &p->cputime_expires;
480 } else {
481 head = p->signal->cpu_timers;
482 cputime_expires = &p->signal->cputime_expires;
483 }
484 head += CPUCLOCK_WHICH(timer->it_clock);
485
486 listpos = head;
487 list_for_each_entry(next, head, entry) {
488 if (nt->expires < next->expires)
489 break;
490 listpos = &next->entry;
491 }
492 list_add(&nt->entry, listpos);
493
494 if (listpos == head) {
495 unsigned long long exp = nt->expires;
496
497 /*
498 * We are the new earliest-expiring POSIX 1.b timer, hence
499 * need to update expiration cache. Take into account that
500 * for process timers we share expiration cache with itimers
501 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
502 */
503
504 switch (CPUCLOCK_WHICH(timer->it_clock)) {
505 case CPUCLOCK_PROF:
506 if (expires_gt(cputime_expires->prof_exp, expires_to_cputime(exp)))
507 cputime_expires->prof_exp = expires_to_cputime(exp);
508 break;
509 case CPUCLOCK_VIRT:
510 if (expires_gt(cputime_expires->virt_exp, expires_to_cputime(exp)))
511 cputime_expires->virt_exp = expires_to_cputime(exp);
512 break;
513 case CPUCLOCK_SCHED:
514 if (cputime_expires->sched_exp == 0 ||
515 cputime_expires->sched_exp > exp)
516 cputime_expires->sched_exp = exp;
517 break;
518 }
519 if (CPUCLOCK_PERTHREAD(timer->it_clock))
520 tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
521 else
522 tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
523 }
524}
525
526/*
527 * The timer is locked, fire it and arrange for its reload.
528 */
529static void cpu_timer_fire(struct k_itimer *timer)
530{
531 if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
532 /*
533 * User don't want any signal.
534 */
535 timer->it.cpu.expires = 0;
536 } else if (unlikely(timer->sigq == NULL)) {
537 /*
538 * This a special case for clock_nanosleep,
539 * not a normal timer from sys_timer_create.
540 */
541 wake_up_process(timer->it_process);
542 timer->it.cpu.expires = 0;
543 } else if (timer->it.cpu.incr == 0) {
544 /*
545 * One-shot timer. Clear it as soon as it's fired.
546 */
547 posix_timer_event(timer, 0);
548 timer->it.cpu.expires = 0;
549 } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
550 /*
551 * The signal did not get queued because the signal
552 * was ignored, so we won't get any callback to
553 * reload the timer. But we need to keep it
554 * ticking in case the signal is deliverable next time.
555 */
556 posix_cpu_timer_schedule(timer);
557 }
558}
559
560/*
561 * Sample a process (thread group) timer for the given group_leader task.
562 * Must be called with task sighand lock held for safe while_each_thread()
563 * traversal.
564 */
565static int cpu_timer_sample_group(const clockid_t which_clock,
566 struct task_struct *p,
567 unsigned long long *sample)
568{
569 struct task_cputime cputime;
570
571 thread_group_cputimer(p, &cputime);
572 switch (CPUCLOCK_WHICH(which_clock)) {
573 default:
574 return -EINVAL;
575 case CPUCLOCK_PROF:
576 *sample = cputime_to_expires(cputime.utime + cputime.stime);
577 break;
578 case CPUCLOCK_VIRT:
579 *sample = cputime_to_expires(cputime.utime);
580 break;
581 case CPUCLOCK_SCHED:
582 *sample = cputime.sum_exec_runtime;
583 break;
584 }
585 return 0;
586}
587
588/*
589 * Guts of sys_timer_settime for CPU timers.
590 * This is called with the timer locked and interrupts disabled.
591 * If we return TIMER_RETRY, it's necessary to release the timer's lock
592 * and try again. (This happens when the timer is in the middle of firing.)
593 */
594static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
595 struct itimerspec *new, struct itimerspec *old)
596{
597 unsigned long flags;
598 struct sighand_struct *sighand;
599 struct task_struct *p = timer->it.cpu.task;
600 unsigned long long old_expires, new_expires, old_incr, val;
601 int ret;
602
603 WARN_ON_ONCE(p == NULL);
604
605 new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
606
607 /*
608 * Protect against sighand release/switch in exit/exec and p->cpu_timers
609 * and p->signal->cpu_timers read/write in arm_timer()
610 */
611 sighand = lock_task_sighand(p, &flags);
612 /*
613 * If p has just been reaped, we can no
614 * longer get any information about it at all.
615 */
616 if (unlikely(sighand == NULL)) {
617 return -ESRCH;
618 }
619
620 /*
621 * Disarm any old timer after extracting its expiry time.
622 */
623 WARN_ON_ONCE(!irqs_disabled());
624
625 ret = 0;
626 old_incr = timer->it.cpu.incr;
627 old_expires = timer->it.cpu.expires;
628 if (unlikely(timer->it.cpu.firing)) {
629 timer->it.cpu.firing = -1;
630 ret = TIMER_RETRY;
631 } else
632 list_del_init(&timer->it.cpu.entry);
633
634 /*
635 * We need to sample the current value to convert the new
636 * value from to relative and absolute, and to convert the
637 * old value from absolute to relative. To set a process
638 * timer, we need a sample to balance the thread expiry
639 * times (in arm_timer). With an absolute time, we must
640 * check if it's already passed. In short, we need a sample.
641 */
642 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
643 cpu_clock_sample(timer->it_clock, p, &val);
644 } else {
645 cpu_timer_sample_group(timer->it_clock, p, &val);
646 }
647
648 if (old) {
649 if (old_expires == 0) {
650 old->it_value.tv_sec = 0;
651 old->it_value.tv_nsec = 0;
652 } else {
653 /*
654 * Update the timer in case it has
655 * overrun already. If it has,
656 * we'll report it as having overrun
657 * and with the next reloaded timer
658 * already ticking, though we are
659 * swallowing that pending
660 * notification here to install the
661 * new setting.
662 */
663 bump_cpu_timer(timer, val);
664 if (val < timer->it.cpu.expires) {
665 old_expires = timer->it.cpu.expires - val;
666 sample_to_timespec(timer->it_clock,
667 old_expires,
668 &old->it_value);
669 } else {
670 old->it_value.tv_nsec = 1;
671 old->it_value.tv_sec = 0;
672 }
673 }
674 }
675
676 if (unlikely(ret)) {
677 /*
678 * We are colliding with the timer actually firing.
679 * Punt after filling in the timer's old value, and
680 * disable this firing since we are already reporting
681 * it as an overrun (thanks to bump_cpu_timer above).
682 */
683 unlock_task_sighand(p, &flags);
684 goto out;
685 }
686
687 if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) {
688 new_expires += val;
689 }
690
691 /*
692 * Install the new expiry time (or zero).
693 * For a timer with no notification action, we don't actually
694 * arm the timer (we'll just fake it for timer_gettime).
695 */
696 timer->it.cpu.expires = new_expires;
697 if (new_expires != 0 && val < new_expires) {
698 arm_timer(timer);
699 }
700
701 unlock_task_sighand(p, &flags);
702 /*
703 * Install the new reload setting, and
704 * set up the signal and overrun bookkeeping.
705 */
706 timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
707 &new->it_interval);
708
709 /*
710 * This acts as a modification timestamp for the timer,
711 * so any automatic reload attempt will punt on seeing
712 * that we have reset the timer manually.
713 */
714 timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
715 ~REQUEUE_PENDING;
716 timer->it_overrun_last = 0;
717 timer->it_overrun = -1;
718
719 if (new_expires != 0 && !(val < new_expires)) {
720 /*
721 * The designated time already passed, so we notify
722 * immediately, even if the thread never runs to
723 * accumulate more time on this clock.
724 */
725 cpu_timer_fire(timer);
726 }
727
728 ret = 0;
729 out:
730 if (old) {
731 sample_to_timespec(timer->it_clock,
732 old_incr, &old->it_interval);
733 }
734
735 return ret;
736}
737
738static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
739{
740 unsigned long long now;
741 struct task_struct *p = timer->it.cpu.task;
742
743 WARN_ON_ONCE(p == NULL);
744
745 /*
746 * Easy part: convert the reload time.
747 */
748 sample_to_timespec(timer->it_clock,
749 timer->it.cpu.incr, &itp->it_interval);
750
751 if (timer->it.cpu.expires == 0) { /* Timer not armed at all. */
752 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
753 return;
754 }
755
756 /*
757 * Sample the clock to take the difference with the expiry time.
758 */
759 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
760 cpu_clock_sample(timer->it_clock, p, &now);
761 } else {
762 struct sighand_struct *sighand;
763 unsigned long flags;
764
765 /*
766 * Protect against sighand release/switch in exit/exec and
767 * also make timer sampling safe if it ends up calling
768 * thread_group_cputime().
769 */
770 sighand = lock_task_sighand(p, &flags);
771 if (unlikely(sighand == NULL)) {
772 /*
773 * The process has been reaped.
774 * We can't even collect a sample any more.
775 * Call the timer disarmed, nothing else to do.
776 */
777 timer->it.cpu.expires = 0;
778 sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
779 &itp->it_value);
780 } else {
781 cpu_timer_sample_group(timer->it_clock, p, &now);
782 unlock_task_sighand(p, &flags);
783 }
784 }
785
786 if (now < timer->it.cpu.expires) {
787 sample_to_timespec(timer->it_clock,
788 timer->it.cpu.expires - now,
789 &itp->it_value);
790 } else {
791 /*
792 * The timer should have expired already, but the firing
793 * hasn't taken place yet. Say it's just about to expire.
794 */
795 itp->it_value.tv_nsec = 1;
796 itp->it_value.tv_sec = 0;
797 }
798}
799
800static unsigned long long
801check_timers_list(struct list_head *timers,
802 struct list_head *firing,
803 unsigned long long curr)
804{
805 int maxfire = 20;
806
807 while (!list_empty(timers)) {
808 struct cpu_timer_list *t;
809
810 t = list_first_entry(timers, struct cpu_timer_list, entry);
811
812 if (!--maxfire || curr < t->expires)
813 return t->expires;
814
815 t->firing = 1;
816 list_move_tail(&t->entry, firing);
817 }
818
819 return 0;
820}
821
822/*
823 * Check for any per-thread CPU timers that have fired and move them off
824 * the tsk->cpu_timers[N] list onto the firing list. Here we update the
825 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
826 */
827static void check_thread_timers(struct task_struct *tsk,
828 struct list_head *firing)
829{
830 struct list_head *timers = tsk->cpu_timers;
831 struct signal_struct *const sig = tsk->signal;
832 struct task_cputime *tsk_expires = &tsk->cputime_expires;
833 unsigned long long expires;
834 unsigned long soft;
835
836 /*
837 * If cputime_expires is zero, then there are no active
838 * per thread CPU timers.
839 */
840 if (task_cputime_zero(&tsk->cputime_expires))
841 return;
842
843 expires = check_timers_list(timers, firing, prof_ticks(tsk));
844 tsk_expires->prof_exp = expires_to_cputime(expires);
845
846 expires = check_timers_list(++timers, firing, virt_ticks(tsk));
847 tsk_expires->virt_exp = expires_to_cputime(expires);
848
849 tsk_expires->sched_exp = check_timers_list(++timers, firing,
850 tsk->se.sum_exec_runtime);
851
852 /*
853 * Check for the special case thread timers.
854 */
855 soft = READ_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
856 if (soft != RLIM_INFINITY) {
857 unsigned long hard =
858 READ_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
859
860 if (hard != RLIM_INFINITY &&
861 tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
862 /*
863 * At the hard limit, we just die.
864 * No need to calculate anything else now.
865 */
866 __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
867 return;
868 }
869 if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
870 /*
871 * At the soft limit, send a SIGXCPU every second.
872 */
873 if (soft < hard) {
874 soft += USEC_PER_SEC;
875 sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
876 }
877 printk(KERN_INFO
878 "RT Watchdog Timeout: %s[%d]\n",
879 tsk->comm, task_pid_nr(tsk));
880 __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
881 }
882 }
883 if (task_cputime_zero(tsk_expires))
884 tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
885}
886
887static inline void stop_process_timers(struct signal_struct *sig)
888{
889 struct thread_group_cputimer *cputimer = &sig->cputimer;
890
891 /* Turn off cputimer->running. This is done without locking. */
892 WRITE_ONCE(cputimer->running, false);
893 tick_dep_clear_signal(sig, TICK_DEP_BIT_POSIX_TIMER);
894}
895
896static u32 onecputick;
897
898static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
899 unsigned long long *expires,
900 unsigned long long cur_time, int signo)
901{
902 if (!it->expires)
903 return;
904
905 if (cur_time >= it->expires) {
906 if (it->incr) {
907 it->expires += it->incr;
908 it->error += it->incr_error;
909 if (it->error >= onecputick) {
910 it->expires -= cputime_one_jiffy;
911 it->error -= onecputick;
912 }
913 } else {
914 it->expires = 0;
915 }
916
917 trace_itimer_expire(signo == SIGPROF ?
918 ITIMER_PROF : ITIMER_VIRTUAL,
919 tsk->signal->leader_pid, cur_time);
920 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
921 }
922
923 if (it->expires && (!*expires || it->expires < *expires)) {
924 *expires = it->expires;
925 }
926}
927
928/*
929 * Check for any per-thread CPU timers that have fired and move them
930 * off the tsk->*_timers list onto the firing list. Per-thread timers
931 * have already been taken off.
932 */
933static void check_process_timers(struct task_struct *tsk,
934 struct list_head *firing)
935{
936 struct signal_struct *const sig = tsk->signal;
937 unsigned long long utime, ptime, virt_expires, prof_expires;
938 unsigned long long sum_sched_runtime, sched_expires;
939 struct list_head *timers = sig->cpu_timers;
940 struct task_cputime cputime;
941 unsigned long soft;
942
943 /*
944 * If cputimer is not running, then there are no active
945 * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU).
946 */
947 if (!READ_ONCE(tsk->signal->cputimer.running))
948 return;
949
950 /*
951 * Signify that a thread is checking for process timers.
952 * Write access to this field is protected by the sighand lock.
953 */
954 sig->cputimer.checking_timer = true;
955
956 /*
957 * Collect the current process totals.
958 */
959 thread_group_cputimer(tsk, &cputime);
960 utime = cputime_to_expires(cputime.utime);
961 ptime = utime + cputime_to_expires(cputime.stime);
962 sum_sched_runtime = cputime.sum_exec_runtime;
963
964 prof_expires = check_timers_list(timers, firing, ptime);
965 virt_expires = check_timers_list(++timers, firing, utime);
966 sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);
967
968 /*
969 * Check for the special case process timers.
970 */
971 check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
972 SIGPROF);
973 check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
974 SIGVTALRM);
975 soft = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
976 if (soft != RLIM_INFINITY) {
977 unsigned long psecs = cputime_to_secs(ptime);
978 unsigned long hard =
979 READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
980 cputime_t x;
981 if (psecs >= hard) {
982 /*
983 * At the hard limit, we just die.
984 * No need to calculate anything else now.
985 */
986 __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
987 return;
988 }
989 if (psecs >= soft) {
990 /*
991 * At the soft limit, send a SIGXCPU every second.
992 */
993 __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
994 if (soft < hard) {
995 soft++;
996 sig->rlim[RLIMIT_CPU].rlim_cur = soft;
997 }
998 }
999 x = secs_to_cputime(soft);
1000 if (!prof_expires || x < prof_expires) {
1001 prof_expires = x;
1002 }
1003 }
1004
1005 sig->cputime_expires.prof_exp = expires_to_cputime(prof_expires);
1006 sig->cputime_expires.virt_exp = expires_to_cputime(virt_expires);
1007 sig->cputime_expires.sched_exp = sched_expires;
1008 if (task_cputime_zero(&sig->cputime_expires))
1009 stop_process_timers(sig);
1010
1011 sig->cputimer.checking_timer = false;
1012}
1013
1014/*
1015 * This is called from the signal code (via do_schedule_next_timer)
1016 * when the last timer signal was delivered and we have to reload the timer.
1017 */
1018void posix_cpu_timer_schedule(struct k_itimer *timer)
1019{
1020 struct sighand_struct *sighand;
1021 unsigned long flags;
1022 struct task_struct *p = timer->it.cpu.task;
1023 unsigned long long now;
1024
1025 WARN_ON_ONCE(p == NULL);
1026
1027 /*
1028 * Fetch the current sample and update the timer's expiry time.
1029 */
1030 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1031 cpu_clock_sample(timer->it_clock, p, &now);
1032 bump_cpu_timer(timer, now);
1033 if (unlikely(p->exit_state))
1034 goto out;
1035
1036 /* Protect timer list r/w in arm_timer() */
1037 sighand = lock_task_sighand(p, &flags);
1038 if (!sighand)
1039 goto out;
1040 } else {
1041 /*
1042 * Protect arm_timer() and timer sampling in case of call to
1043 * thread_group_cputime().
1044 */
1045 sighand = lock_task_sighand(p, &flags);
1046 if (unlikely(sighand == NULL)) {
1047 /*
1048 * The process has been reaped.
1049 * We can't even collect a sample any more.
1050 */
1051 timer->it.cpu.expires = 0;
1052 goto out;
1053 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1054 unlock_task_sighand(p, &flags);
1055 /* Optimizations: if the process is dying, no need to rearm */
1056 goto out;
1057 }
1058 cpu_timer_sample_group(timer->it_clock, p, &now);
1059 bump_cpu_timer(timer, now);
1060 /* Leave the sighand locked for the call below. */
1061 }
1062
1063 /*
1064 * Now re-arm for the new expiry time.
1065 */
1066 WARN_ON_ONCE(!irqs_disabled());
1067 arm_timer(timer);
1068 unlock_task_sighand(p, &flags);
1069
1070out:
1071 timer->it_overrun_last = timer->it_overrun;
1072 timer->it_overrun = -1;
1073 ++timer->it_requeue_pending;
1074}
1075
1076/**
1077 * task_cputime_expired - Compare two task_cputime entities.
1078 *
1079 * @sample: The task_cputime structure to be checked for expiration.
1080 * @expires: Expiration times, against which @sample will be checked.
1081 *
1082 * Checks @sample against @expires to see if any field of @sample has expired.
1083 * Returns true if any field of the former is greater than the corresponding
1084 * field of the latter if the latter field is set. Otherwise returns false.
1085 */
1086static inline int task_cputime_expired(const struct task_cputime *sample,
1087 const struct task_cputime *expires)
1088{
1089 if (expires->utime && sample->utime >= expires->utime)
1090 return 1;
1091 if (expires->stime && sample->utime + sample->stime >= expires->stime)
1092 return 1;
1093 if (expires->sum_exec_runtime != 0 &&
1094 sample->sum_exec_runtime >= expires->sum_exec_runtime)
1095 return 1;
1096 return 0;
1097}
1098
1099/**
1100 * fastpath_timer_check - POSIX CPU timers fast path.
1101 *
1102 * @tsk: The task (thread) being checked.
1103 *
1104 * Check the task and thread group timers. If both are zero (there are no
1105 * timers set) return false. Otherwise snapshot the task and thread group
1106 * timers and compare them with the corresponding expiration times. Return
1107 * true if a timer has expired, else return false.
1108 */
1109static inline int fastpath_timer_check(struct task_struct *tsk)
1110{
1111 struct signal_struct *sig;
1112
1113 if (!task_cputime_zero(&tsk->cputime_expires)) {
1114 struct task_cputime task_sample;
1115
1116 task_cputime(tsk, &task_sample.utime, &task_sample.stime);
1117 task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
1118 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1119 return 1;
1120 }
1121
1122 sig = tsk->signal;
1123 /*
1124 * Check if thread group timers expired when the cputimer is
1125 * running and no other thread in the group is already checking
1126 * for thread group cputimers. These fields are read without the
1127 * sighand lock. However, this is fine because this is meant to
1128 * be a fastpath heuristic to determine whether we should try to
1129 * acquire the sighand lock to check/handle timers.
1130 *
1131 * In the worst case scenario, if 'running' or 'checking_timer' gets
1132 * set but the current thread doesn't see the change yet, we'll wait
1133 * until the next thread in the group gets a scheduler interrupt to
1134 * handle the timer. This isn't an issue in practice because these
1135 * types of delays with signals actually getting sent are expected.
1136 */
1137 if (READ_ONCE(sig->cputimer.running) &&
1138 !READ_ONCE(sig->cputimer.checking_timer)) {
1139 struct task_cputime group_sample;
1140
1141 sample_cputime_atomic(&group_sample, &sig->cputimer.cputime_atomic);
1142
1143 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1144 return 1;
1145 }
1146
1147 return 0;
1148}
1149
1150/*
1151 * This is called from the timer interrupt handler. The irq handler has
1152 * already updated our counts. We need to check if any timers fire now.
1153 * Interrupts are disabled.
1154 */
1155void run_posix_cpu_timers(struct task_struct *tsk)
1156{
1157 LIST_HEAD(firing);
1158 struct k_itimer *timer, *next;
1159 unsigned long flags;
1160
1161 WARN_ON_ONCE(!irqs_disabled());
1162
1163 /*
1164 * The fast path checks that there are no expired thread or thread
1165 * group timers. If that's so, just return.
1166 */
1167 if (!fastpath_timer_check(tsk))
1168 return;
1169
1170 if (!lock_task_sighand(tsk, &flags))
1171 return;
1172 /*
1173 * Here we take off tsk->signal->cpu_timers[N] and
1174 * tsk->cpu_timers[N] all the timers that are firing, and
1175 * put them on the firing list.
1176 */
1177 check_thread_timers(tsk, &firing);
1178
1179 check_process_timers(tsk, &firing);
1180
1181 /*
1182 * We must release these locks before taking any timer's lock.
1183 * There is a potential race with timer deletion here, as the
1184 * siglock now protects our private firing list. We have set
1185 * the firing flag in each timer, so that a deletion attempt
1186 * that gets the timer lock before we do will give it up and
1187 * spin until we've taken care of that timer below.
1188 */
1189 unlock_task_sighand(tsk, &flags);
1190
1191 /*
1192 * Now that all the timers on our list have the firing flag,
1193 * no one will touch their list entries but us. We'll take
1194 * each timer's lock before clearing its firing flag, so no
1195 * timer call will interfere.
1196 */
1197 list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1198 int cpu_firing;
1199
1200 spin_lock(&timer->it_lock);
1201 list_del_init(&timer->it.cpu.entry);
1202 cpu_firing = timer->it.cpu.firing;
1203 timer->it.cpu.firing = 0;
1204 /*
1205 * The firing flag is -1 if we collided with a reset
1206 * of the timer, which already reported this
1207 * almost-firing as an overrun. So don't generate an event.
1208 */
1209 if (likely(cpu_firing >= 0))
1210 cpu_timer_fire(timer);
1211 spin_unlock(&timer->it_lock);
1212 }
1213}
1214
1215/*
1216 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1217 * The tsk->sighand->siglock must be held by the caller.
1218 */
1219void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1220 cputime_t *newval, cputime_t *oldval)
1221{
1222 unsigned long long now;
1223
1224 WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED);
1225 cpu_timer_sample_group(clock_idx, tsk, &now);
1226
1227 if (oldval) {
1228 /*
1229 * We are setting itimer. The *oldval is absolute and we update
1230 * it to be relative, *newval argument is relative and we update
1231 * it to be absolute.
1232 */
1233 if (*oldval) {
1234 if (*oldval <= now) {
1235 /* Just about to fire. */
1236 *oldval = cputime_one_jiffy;
1237 } else {
1238 *oldval -= now;
1239 }
1240 }
1241
1242 if (!*newval)
1243 return;
1244 *newval += now;
1245 }
1246
1247 /*
1248 * Update expiration cache if we are the earliest timer, or eventually
1249 * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1250 */
1251 switch (clock_idx) {
1252 case CPUCLOCK_PROF:
1253 if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1254 tsk->signal->cputime_expires.prof_exp = *newval;
1255 break;
1256 case CPUCLOCK_VIRT:
1257 if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1258 tsk->signal->cputime_expires.virt_exp = *newval;
1259 break;
1260 }
1261
1262 tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER);
1263}
1264
1265static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1266 struct timespec *rqtp, struct itimerspec *it)
1267{
1268 struct k_itimer timer;
1269 int error;
1270
1271 /*
1272 * Set up a temporary timer and then wait for it to go off.
1273 */
1274 memset(&timer, 0, sizeof timer);
1275 spin_lock_init(&timer.it_lock);
1276 timer.it_clock = which_clock;
1277 timer.it_overrun = -1;
1278 error = posix_cpu_timer_create(&timer);
1279 timer.it_process = current;
1280 if (!error) {
1281 static struct itimerspec zero_it;
1282
1283 memset(it, 0, sizeof *it);
1284 it->it_value = *rqtp;
1285
1286 spin_lock_irq(&timer.it_lock);
1287 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1288 if (error) {
1289 spin_unlock_irq(&timer.it_lock);
1290 return error;
1291 }
1292
1293 while (!signal_pending(current)) {
1294 if (timer.it.cpu.expires == 0) {
1295 /*
1296 * Our timer fired and was reset, below
1297 * deletion can not fail.
1298 */
1299 posix_cpu_timer_del(&timer);
1300 spin_unlock_irq(&timer.it_lock);
1301 return 0;
1302 }
1303
1304 /*
1305 * Block until cpu_timer_fire (or a signal) wakes us.
1306 */
1307 __set_current_state(TASK_INTERRUPTIBLE);
1308 spin_unlock_irq(&timer.it_lock);
1309 schedule();
1310 spin_lock_irq(&timer.it_lock);
1311 }
1312
1313 /*
1314 * We were interrupted by a signal.
1315 */
1316 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1317 error = posix_cpu_timer_set(&timer, 0, &zero_it, it);
1318 if (!error) {
1319 /*
1320 * Timer is now unarmed, deletion can not fail.
1321 */
1322 posix_cpu_timer_del(&timer);
1323 }
1324 spin_unlock_irq(&timer.it_lock);
1325
1326 while (error == TIMER_RETRY) {
1327 /*
1328 * We need to handle case when timer was or is in the
1329 * middle of firing. In other cases we already freed
1330 * resources.
1331 */
1332 spin_lock_irq(&timer.it_lock);
1333 error = posix_cpu_timer_del(&timer);
1334 spin_unlock_irq(&timer.it_lock);
1335 }
1336
1337 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1338 /*
1339 * It actually did fire already.
1340 */
1341 return 0;
1342 }
1343
1344 error = -ERESTART_RESTARTBLOCK;
1345 }
1346
1347 return error;
1348}
1349
1350static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1351
1352static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1353 struct timespec *rqtp, struct timespec __user *rmtp)
1354{
1355 struct restart_block *restart_block = ¤t->restart_block;
1356 struct itimerspec it;
1357 int error;
1358
1359 /*
1360 * Diagnose required errors first.
1361 */
1362 if (CPUCLOCK_PERTHREAD(which_clock) &&
1363 (CPUCLOCK_PID(which_clock) == 0 ||
1364 CPUCLOCK_PID(which_clock) == current->pid))
1365 return -EINVAL;
1366
1367 error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1368
1369 if (error == -ERESTART_RESTARTBLOCK) {
1370
1371 if (flags & TIMER_ABSTIME)
1372 return -ERESTARTNOHAND;
1373 /*
1374 * Report back to the user the time still remaining.
1375 */
1376 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1377 return -EFAULT;
1378
1379 restart_block->fn = posix_cpu_nsleep_restart;
1380 restart_block->nanosleep.clockid = which_clock;
1381 restart_block->nanosleep.rmtp = rmtp;
1382 restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1383 }
1384 return error;
1385}
1386
1387static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1388{
1389 clockid_t which_clock = restart_block->nanosleep.clockid;
1390 struct timespec t;
1391 struct itimerspec it;
1392 int error;
1393
1394 t = ns_to_timespec(restart_block->nanosleep.expires);
1395
1396 error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1397
1398 if (error == -ERESTART_RESTARTBLOCK) {
1399 struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1400 /*
1401 * Report back to the user the time still remaining.
1402 */
1403 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1404 return -EFAULT;
1405
1406 restart_block->nanosleep.expires = timespec_to_ns(&t);
1407 }
1408 return error;
1409
1410}
1411
1412#define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1413#define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1414
1415static int process_cpu_clock_getres(const clockid_t which_clock,
1416 struct timespec *tp)
1417{
1418 return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1419}
1420static int process_cpu_clock_get(const clockid_t which_clock,
1421 struct timespec *tp)
1422{
1423 return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1424}
1425static int process_cpu_timer_create(struct k_itimer *timer)
1426{
1427 timer->it_clock = PROCESS_CLOCK;
1428 return posix_cpu_timer_create(timer);
1429}
1430static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1431 struct timespec *rqtp,
1432 struct timespec __user *rmtp)
1433{
1434 return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1435}
1436static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1437{
1438 return -EINVAL;
1439}
1440static int thread_cpu_clock_getres(const clockid_t which_clock,
1441 struct timespec *tp)
1442{
1443 return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1444}
1445static int thread_cpu_clock_get(const clockid_t which_clock,
1446 struct timespec *tp)
1447{
1448 return posix_cpu_clock_get(THREAD_CLOCK, tp);
1449}
1450static int thread_cpu_timer_create(struct k_itimer *timer)
1451{
1452 timer->it_clock = THREAD_CLOCK;
1453 return posix_cpu_timer_create(timer);
1454}
1455
1456struct k_clock clock_posix_cpu = {
1457 .clock_getres = posix_cpu_clock_getres,
1458 .clock_set = posix_cpu_clock_set,
1459 .clock_get = posix_cpu_clock_get,
1460 .timer_create = posix_cpu_timer_create,
1461 .nsleep = posix_cpu_nsleep,
1462 .nsleep_restart = posix_cpu_nsleep_restart,
1463 .timer_set = posix_cpu_timer_set,
1464 .timer_del = posix_cpu_timer_del,
1465 .timer_get = posix_cpu_timer_get,
1466};
1467
1468static __init int init_posix_cpu_timers(void)
1469{
1470 struct k_clock process = {
1471 .clock_getres = process_cpu_clock_getres,
1472 .clock_get = process_cpu_clock_get,
1473 .timer_create = process_cpu_timer_create,
1474 .nsleep = process_cpu_nsleep,
1475 .nsleep_restart = process_cpu_nsleep_restart,
1476 };
1477 struct k_clock thread = {
1478 .clock_getres = thread_cpu_clock_getres,
1479 .clock_get = thread_cpu_clock_get,
1480 .timer_create = thread_cpu_timer_create,
1481 };
1482 struct timespec ts;
1483
1484 posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1485 posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1486
1487 cputime_to_timespec(cputime_one_jiffy, &ts);
1488 onecputick = ts.tv_nsec;
1489 WARN_ON(ts.tv_sec != 0);
1490
1491 return 0;
1492}
1493__initcall(init_posix_cpu_timers);
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
21static void posix_cpu_timer_rearm(struct k_itimer *timer);
22
23void posix_cputimers_group_init(struct posix_cputimers *pct, u64 cpu_limit)
24{
25 posix_cputimers_init(pct);
26 if (cpu_limit != RLIM_INFINITY) {
27 pct->bases[CPUCLOCK_PROF].nextevt = cpu_limit * NSEC_PER_SEC;
28 pct->timers_active = true;
29 }
30}
31
32/*
33 * Called after updating RLIMIT_CPU to run cpu timer and update
34 * tsk->signal->posix_cputimers.bases[clock].nextevt expiration cache if
35 * necessary. Needs siglock protection since other code may update the
36 * expiration cache as well.
37 */
38void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
39{
40 u64 nsecs = rlim_new * NSEC_PER_SEC;
41
42 spin_lock_irq(&task->sighand->siglock);
43 set_process_cpu_timer(task, CPUCLOCK_PROF, &nsecs, NULL);
44 spin_unlock_irq(&task->sighand->siglock);
45}
46
47/*
48 * Functions for validating access to tasks.
49 */
50static struct pid *pid_for_clock(const clockid_t clock, bool gettime)
51{
52 const bool thread = !!CPUCLOCK_PERTHREAD(clock);
53 const pid_t upid = CPUCLOCK_PID(clock);
54 struct pid *pid;
55
56 if (CPUCLOCK_WHICH(clock) >= CPUCLOCK_MAX)
57 return NULL;
58
59 /*
60 * If the encoded PID is 0, then the timer is targeted at current
61 * or the process to which current belongs.
62 */
63 if (upid == 0)
64 return thread ? task_pid(current) : task_tgid(current);
65
66 pid = find_vpid(upid);
67 if (!pid)
68 return NULL;
69
70 if (thread) {
71 struct task_struct *tsk = pid_task(pid, PIDTYPE_PID);
72 return (tsk && same_thread_group(tsk, current)) ? pid : NULL;
73 }
74
75 /*
76 * For clock_gettime(PROCESS) allow finding the process by
77 * with the pid of the current task. The code needs the tgid
78 * of the process so that pid_task(pid, PIDTYPE_TGID) can be
79 * used to find the process.
80 */
81 if (gettime && (pid == task_pid(current)))
82 return task_tgid(current);
83
84 /*
85 * For processes require that pid identifies a process.
86 */
87 return pid_has_task(pid, PIDTYPE_TGID) ? pid : NULL;
88}
89
90static inline int validate_clock_permissions(const clockid_t clock)
91{
92 int ret;
93
94 rcu_read_lock();
95 ret = pid_for_clock(clock, false) ? 0 : -EINVAL;
96 rcu_read_unlock();
97
98 return ret;
99}
100
101static inline enum pid_type clock_pid_type(const clockid_t clock)
102{
103 return CPUCLOCK_PERTHREAD(clock) ? PIDTYPE_PID : PIDTYPE_TGID;
104}
105
106static inline struct task_struct *cpu_timer_task_rcu(struct k_itimer *timer)
107{
108 return pid_task(timer->it.cpu.pid, clock_pid_type(timer->it_clock));
109}
110
111/*
112 * Update expiry time from increment, and increase overrun count,
113 * given the current clock sample.
114 */
115static u64 bump_cpu_timer(struct k_itimer *timer, u64 now)
116{
117 u64 delta, incr, expires = timer->it.cpu.node.expires;
118 int i;
119
120 if (!timer->it_interval)
121 return expires;
122
123 if (now < expires)
124 return expires;
125
126 incr = timer->it_interval;
127 delta = now + incr - expires;
128
129 /* Don't use (incr*2 < delta), incr*2 might overflow. */
130 for (i = 0; incr < delta - incr; i++)
131 incr = incr << 1;
132
133 for (; i >= 0; incr >>= 1, i--) {
134 if (delta < incr)
135 continue;
136
137 timer->it.cpu.node.expires += incr;
138 timer->it_overrun += 1LL << i;
139 delta -= incr;
140 }
141 return timer->it.cpu.node.expires;
142}
143
144/* Check whether all cache entries contain U64_MAX, i.e. eternal expiry time */
145static inline bool expiry_cache_is_inactive(const struct posix_cputimers *pct)
146{
147 return !(~pct->bases[CPUCLOCK_PROF].nextevt |
148 ~pct->bases[CPUCLOCK_VIRT].nextevt |
149 ~pct->bases[CPUCLOCK_SCHED].nextevt);
150}
151
152static int
153posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
154{
155 int error = validate_clock_permissions(which_clock);
156
157 if (!error) {
158 tp->tv_sec = 0;
159 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
160 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
161 /*
162 * If sched_clock is using a cycle counter, we
163 * don't have any idea of its true resolution
164 * exported, but it is much more than 1s/HZ.
165 */
166 tp->tv_nsec = 1;
167 }
168 }
169 return error;
170}
171
172static int
173posix_cpu_clock_set(const clockid_t clock, const struct timespec64 *tp)
174{
175 int error = validate_clock_permissions(clock);
176
177 /*
178 * You can never reset a CPU clock, but we check for other errors
179 * in the call before failing with EPERM.
180 */
181 return error ? : -EPERM;
182}
183
184/*
185 * Sample a per-thread clock for the given task. clkid is validated.
186 */
187static u64 cpu_clock_sample(const clockid_t clkid, struct task_struct *p)
188{
189 u64 utime, stime;
190
191 if (clkid == CPUCLOCK_SCHED)
192 return task_sched_runtime(p);
193
194 task_cputime(p, &utime, &stime);
195
196 switch (clkid) {
197 case CPUCLOCK_PROF:
198 return utime + stime;
199 case CPUCLOCK_VIRT:
200 return utime;
201 default:
202 WARN_ON_ONCE(1);
203 }
204 return 0;
205}
206
207static inline void store_samples(u64 *samples, u64 stime, u64 utime, u64 rtime)
208{
209 samples[CPUCLOCK_PROF] = stime + utime;
210 samples[CPUCLOCK_VIRT] = utime;
211 samples[CPUCLOCK_SCHED] = rtime;
212}
213
214static void task_sample_cputime(struct task_struct *p, u64 *samples)
215{
216 u64 stime, utime;
217
218 task_cputime(p, &utime, &stime);
219 store_samples(samples, stime, utime, p->se.sum_exec_runtime);
220}
221
222static void proc_sample_cputime_atomic(struct task_cputime_atomic *at,
223 u64 *samples)
224{
225 u64 stime, utime, rtime;
226
227 utime = atomic64_read(&at->utime);
228 stime = atomic64_read(&at->stime);
229 rtime = atomic64_read(&at->sum_exec_runtime);
230 store_samples(samples, stime, utime, rtime);
231}
232
233/*
234 * Set cputime to sum_cputime if sum_cputime > cputime. Use cmpxchg
235 * to avoid race conditions with concurrent updates to cputime.
236 */
237static inline void __update_gt_cputime(atomic64_t *cputime, u64 sum_cputime)
238{
239 u64 curr_cputime;
240retry:
241 curr_cputime = atomic64_read(cputime);
242 if (sum_cputime > curr_cputime) {
243 if (atomic64_cmpxchg(cputime, curr_cputime, sum_cputime) != curr_cputime)
244 goto retry;
245 }
246}
247
248static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic,
249 struct task_cputime *sum)
250{
251 __update_gt_cputime(&cputime_atomic->utime, sum->utime);
252 __update_gt_cputime(&cputime_atomic->stime, sum->stime);
253 __update_gt_cputime(&cputime_atomic->sum_exec_runtime, sum->sum_exec_runtime);
254}
255
256/**
257 * thread_group_sample_cputime - Sample cputime for a given task
258 * @tsk: Task for which cputime needs to be started
259 * @samples: Storage for time samples
260 *
261 * Called from sys_getitimer() to calculate the expiry time of an active
262 * timer. That means group cputime accounting is already active. Called
263 * with task sighand lock held.
264 *
265 * Updates @times with an uptodate sample of the thread group cputimes.
266 */
267void thread_group_sample_cputime(struct task_struct *tsk, u64 *samples)
268{
269 struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
270 struct posix_cputimers *pct = &tsk->signal->posix_cputimers;
271
272 WARN_ON_ONCE(!pct->timers_active);
273
274 proc_sample_cputime_atomic(&cputimer->cputime_atomic, samples);
275}
276
277/**
278 * thread_group_start_cputime - Start cputime and return a sample
279 * @tsk: Task for which cputime needs to be started
280 * @samples: Storage for time samples
281 *
282 * The thread group cputime accounting is avoided when there are no posix
283 * CPU timers armed. Before starting a timer it's required to check whether
284 * the time accounting is active. If not, a full update of the atomic
285 * accounting store needs to be done and the accounting enabled.
286 *
287 * Updates @times with an uptodate sample of the thread group cputimes.
288 */
289static void thread_group_start_cputime(struct task_struct *tsk, u64 *samples)
290{
291 struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
292 struct posix_cputimers *pct = &tsk->signal->posix_cputimers;
293
294 /* Check if cputimer isn't running. This is accessed without locking. */
295 if (!READ_ONCE(pct->timers_active)) {
296 struct task_cputime sum;
297
298 /*
299 * The POSIX timer interface allows for absolute time expiry
300 * values through the TIMER_ABSTIME flag, therefore we have
301 * to synchronize the timer to the clock every time we start it.
302 */
303 thread_group_cputime(tsk, &sum);
304 update_gt_cputime(&cputimer->cputime_atomic, &sum);
305
306 /*
307 * We're setting timers_active without a lock. Ensure this
308 * only gets written to in one operation. We set it after
309 * update_gt_cputime() as a small optimization, but
310 * barriers are not required because update_gt_cputime()
311 * can handle concurrent updates.
312 */
313 WRITE_ONCE(pct->timers_active, true);
314 }
315 proc_sample_cputime_atomic(&cputimer->cputime_atomic, samples);
316}
317
318static void __thread_group_cputime(struct task_struct *tsk, u64 *samples)
319{
320 struct task_cputime ct;
321
322 thread_group_cputime(tsk, &ct);
323 store_samples(samples, ct.stime, ct.utime, ct.sum_exec_runtime);
324}
325
326/*
327 * Sample a process (thread group) clock for the given task clkid. If the
328 * group's cputime accounting is already enabled, read the atomic
329 * store. Otherwise a full update is required. clkid is already validated.
330 */
331static u64 cpu_clock_sample_group(const clockid_t clkid, struct task_struct *p,
332 bool start)
333{
334 struct thread_group_cputimer *cputimer = &p->signal->cputimer;
335 struct posix_cputimers *pct = &p->signal->posix_cputimers;
336 u64 samples[CPUCLOCK_MAX];
337
338 if (!READ_ONCE(pct->timers_active)) {
339 if (start)
340 thread_group_start_cputime(p, samples);
341 else
342 __thread_group_cputime(p, samples);
343 } else {
344 proc_sample_cputime_atomic(&cputimer->cputime_atomic, samples);
345 }
346
347 return samples[clkid];
348}
349
350static int posix_cpu_clock_get(const clockid_t clock, struct timespec64 *tp)
351{
352 const clockid_t clkid = CPUCLOCK_WHICH(clock);
353 struct task_struct *tsk;
354 u64 t;
355
356 rcu_read_lock();
357 tsk = pid_task(pid_for_clock(clock, true), clock_pid_type(clock));
358 if (!tsk) {
359 rcu_read_unlock();
360 return -EINVAL;
361 }
362
363 if (CPUCLOCK_PERTHREAD(clock))
364 t = cpu_clock_sample(clkid, tsk);
365 else
366 t = cpu_clock_sample_group(clkid, tsk, false);
367 rcu_read_unlock();
368
369 *tp = ns_to_timespec64(t);
370 return 0;
371}
372
373/*
374 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
375 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
376 * new timer already all-zeros initialized.
377 */
378static int posix_cpu_timer_create(struct k_itimer *new_timer)
379{
380 static struct lock_class_key posix_cpu_timers_key;
381 struct pid *pid;
382
383 rcu_read_lock();
384 pid = pid_for_clock(new_timer->it_clock, false);
385 if (!pid) {
386 rcu_read_unlock();
387 return -EINVAL;
388 }
389
390 /*
391 * If posix timer expiry is handled in task work context then
392 * timer::it_lock can be taken without disabling interrupts as all
393 * other locking happens in task context. This requires a separate
394 * lock class key otherwise regular posix timer expiry would record
395 * the lock class being taken in interrupt context and generate a
396 * false positive warning.
397 */
398 if (IS_ENABLED(CONFIG_POSIX_CPU_TIMERS_TASK_WORK))
399 lockdep_set_class(&new_timer->it_lock, &posix_cpu_timers_key);
400
401 new_timer->kclock = &clock_posix_cpu;
402 timerqueue_init(&new_timer->it.cpu.node);
403 new_timer->it.cpu.pid = get_pid(pid);
404 rcu_read_unlock();
405 return 0;
406}
407
408/*
409 * Clean up a CPU-clock timer that is about to be destroyed.
410 * This is called from timer deletion with the timer already locked.
411 * If we return TIMER_RETRY, it's necessary to release the timer's lock
412 * and try again. (This happens when the timer is in the middle of firing.)
413 */
414static int posix_cpu_timer_del(struct k_itimer *timer)
415{
416 struct cpu_timer *ctmr = &timer->it.cpu;
417 struct sighand_struct *sighand;
418 struct task_struct *p;
419 unsigned long flags;
420 int ret = 0;
421
422 rcu_read_lock();
423 p = cpu_timer_task_rcu(timer);
424 if (!p)
425 goto out;
426
427 /*
428 * Protect against sighand release/switch in exit/exec and process/
429 * thread timer list entry concurrent read/writes.
430 */
431 sighand = lock_task_sighand(p, &flags);
432 if (unlikely(sighand == NULL)) {
433 /*
434 * This raced with the reaping of the task. The exit cleanup
435 * should have removed this timer from the timer queue.
436 */
437 WARN_ON_ONCE(ctmr->head || timerqueue_node_queued(&ctmr->node));
438 } else {
439 if (timer->it.cpu.firing)
440 ret = TIMER_RETRY;
441 else
442 cpu_timer_dequeue(ctmr);
443
444 unlock_task_sighand(p, &flags);
445 }
446
447out:
448 rcu_read_unlock();
449 if (!ret)
450 put_pid(ctmr->pid);
451
452 return ret;
453}
454
455static void cleanup_timerqueue(struct timerqueue_head *head)
456{
457 struct timerqueue_node *node;
458 struct cpu_timer *ctmr;
459
460 while ((node = timerqueue_getnext(head))) {
461 timerqueue_del(head, node);
462 ctmr = container_of(node, struct cpu_timer, node);
463 ctmr->head = NULL;
464 }
465}
466
467/*
468 * Clean out CPU timers which are still armed when a thread exits. The
469 * timers are only removed from the list. No other updates are done. The
470 * corresponding posix timers are still accessible, but cannot be rearmed.
471 *
472 * This must be called with the siglock held.
473 */
474static void cleanup_timers(struct posix_cputimers *pct)
475{
476 cleanup_timerqueue(&pct->bases[CPUCLOCK_PROF].tqhead);
477 cleanup_timerqueue(&pct->bases[CPUCLOCK_VIRT].tqhead);
478 cleanup_timerqueue(&pct->bases[CPUCLOCK_SCHED].tqhead);
479}
480
481/*
482 * These are both called with the siglock held, when the current thread
483 * is being reaped. When the final (leader) thread in the group is reaped,
484 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
485 */
486void posix_cpu_timers_exit(struct task_struct *tsk)
487{
488 cleanup_timers(&tsk->posix_cputimers);
489}
490void posix_cpu_timers_exit_group(struct task_struct *tsk)
491{
492 cleanup_timers(&tsk->signal->posix_cputimers);
493}
494
495/*
496 * Insert the timer on the appropriate list before any timers that
497 * expire later. This must be called with the sighand lock held.
498 */
499static void arm_timer(struct k_itimer *timer, struct task_struct *p)
500{
501 int clkidx = CPUCLOCK_WHICH(timer->it_clock);
502 struct cpu_timer *ctmr = &timer->it.cpu;
503 u64 newexp = cpu_timer_getexpires(ctmr);
504 struct posix_cputimer_base *base;
505
506 if (CPUCLOCK_PERTHREAD(timer->it_clock))
507 base = p->posix_cputimers.bases + clkidx;
508 else
509 base = p->signal->posix_cputimers.bases + clkidx;
510
511 if (!cpu_timer_enqueue(&base->tqhead, ctmr))
512 return;
513
514 /*
515 * We are the new earliest-expiring POSIX 1.b timer, hence
516 * need to update expiration cache. Take into account that
517 * for process timers we share expiration cache with itimers
518 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
519 */
520 if (newexp < base->nextevt)
521 base->nextevt = newexp;
522
523 if (CPUCLOCK_PERTHREAD(timer->it_clock))
524 tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
525 else
526 tick_dep_set_signal(p, TICK_DEP_BIT_POSIX_TIMER);
527}
528
529/*
530 * The timer is locked, fire it and arrange for its reload.
531 */
532static void cpu_timer_fire(struct k_itimer *timer)
533{
534 struct cpu_timer *ctmr = &timer->it.cpu;
535
536 if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
537 /*
538 * User don't want any signal.
539 */
540 cpu_timer_setexpires(ctmr, 0);
541 } else if (unlikely(timer->sigq == NULL)) {
542 /*
543 * This a special case for clock_nanosleep,
544 * not a normal timer from sys_timer_create.
545 */
546 wake_up_process(timer->it_process);
547 cpu_timer_setexpires(ctmr, 0);
548 } else if (!timer->it_interval) {
549 /*
550 * One-shot timer. Clear it as soon as it's fired.
551 */
552 posix_timer_event(timer, 0);
553 cpu_timer_setexpires(ctmr, 0);
554 } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
555 /*
556 * The signal did not get queued because the signal
557 * was ignored, so we won't get any callback to
558 * reload the timer. But we need to keep it
559 * ticking in case the signal is deliverable next time.
560 */
561 posix_cpu_timer_rearm(timer);
562 ++timer->it_requeue_pending;
563 }
564}
565
566/*
567 * Guts of sys_timer_settime for CPU timers.
568 * This is called with the timer locked and interrupts disabled.
569 * If we return TIMER_RETRY, it's necessary to release the timer's lock
570 * and try again. (This happens when the timer is in the middle of firing.)
571 */
572static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
573 struct itimerspec64 *new, struct itimerspec64 *old)
574{
575 clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
576 u64 old_expires, new_expires, old_incr, val;
577 struct cpu_timer *ctmr = &timer->it.cpu;
578 struct sighand_struct *sighand;
579 struct task_struct *p;
580 unsigned long flags;
581 int ret = 0;
582
583 rcu_read_lock();
584 p = cpu_timer_task_rcu(timer);
585 if (!p) {
586 /*
587 * If p has just been reaped, we can no
588 * longer get any information about it at all.
589 */
590 rcu_read_unlock();
591 return -ESRCH;
592 }
593
594 /*
595 * Use the to_ktime conversion because that clamps the maximum
596 * value to KTIME_MAX and avoid multiplication overflows.
597 */
598 new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value));
599
600 /*
601 * Protect against sighand release/switch in exit/exec and p->cpu_timers
602 * and p->signal->cpu_timers read/write in arm_timer()
603 */
604 sighand = lock_task_sighand(p, &flags);
605 /*
606 * If p has just been reaped, we can no
607 * longer get any information about it at all.
608 */
609 if (unlikely(sighand == NULL)) {
610 rcu_read_unlock();
611 return -ESRCH;
612 }
613
614 /*
615 * Disarm any old timer after extracting its expiry time.
616 */
617 old_incr = timer->it_interval;
618 old_expires = cpu_timer_getexpires(ctmr);
619
620 if (unlikely(timer->it.cpu.firing)) {
621 timer->it.cpu.firing = -1;
622 ret = TIMER_RETRY;
623 } else {
624 cpu_timer_dequeue(ctmr);
625 }
626
627 /*
628 * We need to sample the current value to convert the new
629 * value from to relative and absolute, and to convert the
630 * old value from absolute to relative. To set a process
631 * timer, we need a sample to balance the thread expiry
632 * times (in arm_timer). With an absolute time, we must
633 * check if it's already passed. In short, we need a sample.
634 */
635 if (CPUCLOCK_PERTHREAD(timer->it_clock))
636 val = cpu_clock_sample(clkid, p);
637 else
638 val = cpu_clock_sample_group(clkid, p, true);
639
640 if (old) {
641 if (old_expires == 0) {
642 old->it_value.tv_sec = 0;
643 old->it_value.tv_nsec = 0;
644 } else {
645 /*
646 * Update the timer in case it has overrun already.
647 * If it has, we'll report it as having overrun and
648 * with the next reloaded timer already ticking,
649 * though we are swallowing that pending
650 * notification here to install the new setting.
651 */
652 u64 exp = bump_cpu_timer(timer, val);
653
654 if (val < exp) {
655 old_expires = exp - val;
656 old->it_value = ns_to_timespec64(old_expires);
657 } else {
658 old->it_value.tv_nsec = 1;
659 old->it_value.tv_sec = 0;
660 }
661 }
662 }
663
664 if (unlikely(ret)) {
665 /*
666 * We are colliding with the timer actually firing.
667 * Punt after filling in the timer's old value, and
668 * disable this firing since we are already reporting
669 * it as an overrun (thanks to bump_cpu_timer above).
670 */
671 unlock_task_sighand(p, &flags);
672 goto out;
673 }
674
675 if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) {
676 new_expires += val;
677 }
678
679 /*
680 * Install the new expiry time (or zero).
681 * For a timer with no notification action, we don't actually
682 * arm the timer (we'll just fake it for timer_gettime).
683 */
684 cpu_timer_setexpires(ctmr, new_expires);
685 if (new_expires != 0 && val < new_expires) {
686 arm_timer(timer, p);
687 }
688
689 unlock_task_sighand(p, &flags);
690 /*
691 * Install the new reload setting, and
692 * set up the signal and overrun bookkeeping.
693 */
694 timer->it_interval = timespec64_to_ktime(new->it_interval);
695
696 /*
697 * This acts as a modification timestamp for the timer,
698 * so any automatic reload attempt will punt on seeing
699 * that we have reset the timer manually.
700 */
701 timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
702 ~REQUEUE_PENDING;
703 timer->it_overrun_last = 0;
704 timer->it_overrun = -1;
705
706 if (new_expires != 0 && !(val < new_expires)) {
707 /*
708 * The designated time already passed, so we notify
709 * immediately, even if the thread never runs to
710 * accumulate more time on this clock.
711 */
712 cpu_timer_fire(timer);
713 }
714
715 ret = 0;
716 out:
717 rcu_read_unlock();
718 if (old)
719 old->it_interval = ns_to_timespec64(old_incr);
720
721 return ret;
722}
723
724static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
725{
726 clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
727 struct cpu_timer *ctmr = &timer->it.cpu;
728 u64 now, expires = cpu_timer_getexpires(ctmr);
729 struct task_struct *p;
730
731 rcu_read_lock();
732 p = cpu_timer_task_rcu(timer);
733 if (!p)
734 goto out;
735
736 /*
737 * Easy part: convert the reload time.
738 */
739 itp->it_interval = ktime_to_timespec64(timer->it_interval);
740
741 if (!expires)
742 goto out;
743
744 /*
745 * Sample the clock to take the difference with the expiry time.
746 */
747 if (CPUCLOCK_PERTHREAD(timer->it_clock))
748 now = cpu_clock_sample(clkid, p);
749 else
750 now = cpu_clock_sample_group(clkid, p, false);
751
752 if (now < expires) {
753 itp->it_value = ns_to_timespec64(expires - now);
754 } else {
755 /*
756 * The timer should have expired already, but the firing
757 * hasn't taken place yet. Say it's just about to expire.
758 */
759 itp->it_value.tv_nsec = 1;
760 itp->it_value.tv_sec = 0;
761 }
762out:
763 rcu_read_unlock();
764}
765
766#define MAX_COLLECTED 20
767
768static u64 collect_timerqueue(struct timerqueue_head *head,
769 struct list_head *firing, u64 now)
770{
771 struct timerqueue_node *next;
772 int i = 0;
773
774 while ((next = timerqueue_getnext(head))) {
775 struct cpu_timer *ctmr;
776 u64 expires;
777
778 ctmr = container_of(next, struct cpu_timer, node);
779 expires = cpu_timer_getexpires(ctmr);
780 /* Limit the number of timers to expire at once */
781 if (++i == MAX_COLLECTED || now < expires)
782 return expires;
783
784 ctmr->firing = 1;
785 cpu_timer_dequeue(ctmr);
786 list_add_tail(&ctmr->elist, firing);
787 }
788
789 return U64_MAX;
790}
791
792static void collect_posix_cputimers(struct posix_cputimers *pct, u64 *samples,
793 struct list_head *firing)
794{
795 struct posix_cputimer_base *base = pct->bases;
796 int i;
797
798 for (i = 0; i < CPUCLOCK_MAX; i++, base++) {
799 base->nextevt = collect_timerqueue(&base->tqhead, firing,
800 samples[i]);
801 }
802}
803
804static inline void check_dl_overrun(struct task_struct *tsk)
805{
806 if (tsk->dl.dl_overrun) {
807 tsk->dl.dl_overrun = 0;
808 __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
809 }
810}
811
812static bool check_rlimit(u64 time, u64 limit, int signo, bool rt, bool hard)
813{
814 if (time < limit)
815 return false;
816
817 if (print_fatal_signals) {
818 pr_info("%s Watchdog Timeout (%s): %s[%d]\n",
819 rt ? "RT" : "CPU", hard ? "hard" : "soft",
820 current->comm, task_pid_nr(current));
821 }
822 __group_send_sig_info(signo, SEND_SIG_PRIV, current);
823 return true;
824}
825
826/*
827 * Check for any per-thread CPU timers that have fired and move them off
828 * the tsk->cpu_timers[N] list onto the firing list. Here we update the
829 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
830 */
831static void check_thread_timers(struct task_struct *tsk,
832 struct list_head *firing)
833{
834 struct posix_cputimers *pct = &tsk->posix_cputimers;
835 u64 samples[CPUCLOCK_MAX];
836 unsigned long soft;
837
838 if (dl_task(tsk))
839 check_dl_overrun(tsk);
840
841 if (expiry_cache_is_inactive(pct))
842 return;
843
844 task_sample_cputime(tsk, samples);
845 collect_posix_cputimers(pct, samples, firing);
846
847 /*
848 * Check for the special case thread timers.
849 */
850 soft = task_rlimit(tsk, RLIMIT_RTTIME);
851 if (soft != RLIM_INFINITY) {
852 /* Task RT timeout is accounted in jiffies. RTTIME is usec */
853 unsigned long rttime = tsk->rt.timeout * (USEC_PER_SEC / HZ);
854 unsigned long hard = task_rlimit_max(tsk, RLIMIT_RTTIME);
855
856 /* At the hard limit, send SIGKILL. No further action. */
857 if (hard != RLIM_INFINITY &&
858 check_rlimit(rttime, hard, SIGKILL, true, true))
859 return;
860
861 /* At the soft limit, send a SIGXCPU every second */
862 if (check_rlimit(rttime, soft, SIGXCPU, true, false)) {
863 soft += USEC_PER_SEC;
864 tsk->signal->rlim[RLIMIT_RTTIME].rlim_cur = soft;
865 }
866 }
867
868 if (expiry_cache_is_inactive(pct))
869 tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
870}
871
872static inline void stop_process_timers(struct signal_struct *sig)
873{
874 struct posix_cputimers *pct = &sig->posix_cputimers;
875
876 /* Turn off the active flag. This is done without locking. */
877 WRITE_ONCE(pct->timers_active, false);
878 tick_dep_clear_signal(sig, TICK_DEP_BIT_POSIX_TIMER);
879}
880
881static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
882 u64 *expires, u64 cur_time, int signo)
883{
884 if (!it->expires)
885 return;
886
887 if (cur_time >= it->expires) {
888 if (it->incr)
889 it->expires += it->incr;
890 else
891 it->expires = 0;
892
893 trace_itimer_expire(signo == SIGPROF ?
894 ITIMER_PROF : ITIMER_VIRTUAL,
895 task_tgid(tsk), cur_time);
896 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
897 }
898
899 if (it->expires && it->expires < *expires)
900 *expires = it->expires;
901}
902
903/*
904 * Check for any per-thread CPU timers that have fired and move them
905 * off the tsk->*_timers list onto the firing list. Per-thread timers
906 * have already been taken off.
907 */
908static void check_process_timers(struct task_struct *tsk,
909 struct list_head *firing)
910{
911 struct signal_struct *const sig = tsk->signal;
912 struct posix_cputimers *pct = &sig->posix_cputimers;
913 u64 samples[CPUCLOCK_MAX];
914 unsigned long soft;
915
916 /*
917 * If there are no active process wide timers (POSIX 1.b, itimers,
918 * RLIMIT_CPU) nothing to check. Also skip the process wide timer
919 * processing when there is already another task handling them.
920 */
921 if (!READ_ONCE(pct->timers_active) || pct->expiry_active)
922 return;
923
924 /*
925 * Signify that a thread is checking for process timers.
926 * Write access to this field is protected by the sighand lock.
927 */
928 pct->expiry_active = true;
929
930 /*
931 * Collect the current process totals. Group accounting is active
932 * so the sample can be taken directly.
933 */
934 proc_sample_cputime_atomic(&sig->cputimer.cputime_atomic, samples);
935 collect_posix_cputimers(pct, samples, firing);
936
937 /*
938 * Check for the special case process timers.
939 */
940 check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF],
941 &pct->bases[CPUCLOCK_PROF].nextevt,
942 samples[CPUCLOCK_PROF], SIGPROF);
943 check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT],
944 &pct->bases[CPUCLOCK_VIRT].nextevt,
945 samples[CPUCLOCK_VIRT], SIGVTALRM);
946
947 soft = task_rlimit(tsk, RLIMIT_CPU);
948 if (soft != RLIM_INFINITY) {
949 /* RLIMIT_CPU is in seconds. Samples are nanoseconds */
950 unsigned long hard = task_rlimit_max(tsk, RLIMIT_CPU);
951 u64 ptime = samples[CPUCLOCK_PROF];
952 u64 softns = (u64)soft * NSEC_PER_SEC;
953 u64 hardns = (u64)hard * NSEC_PER_SEC;
954
955 /* At the hard limit, send SIGKILL. No further action. */
956 if (hard != RLIM_INFINITY &&
957 check_rlimit(ptime, hardns, SIGKILL, false, true))
958 return;
959
960 /* At the soft limit, send a SIGXCPU every second */
961 if (check_rlimit(ptime, softns, SIGXCPU, false, false)) {
962 sig->rlim[RLIMIT_CPU].rlim_cur = soft + 1;
963 softns += NSEC_PER_SEC;
964 }
965
966 /* Update the expiry cache */
967 if (softns < pct->bases[CPUCLOCK_PROF].nextevt)
968 pct->bases[CPUCLOCK_PROF].nextevt = softns;
969 }
970
971 if (expiry_cache_is_inactive(pct))
972 stop_process_timers(sig);
973
974 pct->expiry_active = false;
975}
976
977/*
978 * This is called from the signal code (via posixtimer_rearm)
979 * when the last timer signal was delivered and we have to reload the timer.
980 */
981static void posix_cpu_timer_rearm(struct k_itimer *timer)
982{
983 clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
984 struct task_struct *p;
985 struct sighand_struct *sighand;
986 unsigned long flags;
987 u64 now;
988
989 rcu_read_lock();
990 p = cpu_timer_task_rcu(timer);
991 if (!p)
992 goto out;
993
994 /* Protect timer list r/w in arm_timer() */
995 sighand = lock_task_sighand(p, &flags);
996 if (unlikely(sighand == NULL))
997 goto out;
998
999 /*
1000 * Fetch the current sample and update the timer's expiry time.
1001 */
1002 if (CPUCLOCK_PERTHREAD(timer->it_clock))
1003 now = cpu_clock_sample(clkid, p);
1004 else
1005 now = cpu_clock_sample_group(clkid, p, true);
1006
1007 bump_cpu_timer(timer, now);
1008
1009 /*
1010 * Now re-arm for the new expiry time.
1011 */
1012 arm_timer(timer, p);
1013 unlock_task_sighand(p, &flags);
1014out:
1015 rcu_read_unlock();
1016}
1017
1018/**
1019 * task_cputimers_expired - Check whether posix CPU timers are expired
1020 *
1021 * @samples: Array of current samples for the CPUCLOCK clocks
1022 * @pct: Pointer to a posix_cputimers container
1023 *
1024 * Returns true if any member of @samples is greater than the corresponding
1025 * member of @pct->bases[CLK].nextevt. False otherwise
1026 */
1027static inline bool
1028task_cputimers_expired(const u64 *samples, struct posix_cputimers *pct)
1029{
1030 int i;
1031
1032 for (i = 0; i < CPUCLOCK_MAX; i++) {
1033 if (samples[i] >= pct->bases[i].nextevt)
1034 return true;
1035 }
1036 return false;
1037}
1038
1039/**
1040 * fastpath_timer_check - POSIX CPU timers fast path.
1041 *
1042 * @tsk: The task (thread) being checked.
1043 *
1044 * Check the task and thread group timers. If both are zero (there are no
1045 * timers set) return false. Otherwise snapshot the task and thread group
1046 * timers and compare them with the corresponding expiration times. Return
1047 * true if a timer has expired, else return false.
1048 */
1049static inline bool fastpath_timer_check(struct task_struct *tsk)
1050{
1051 struct posix_cputimers *pct = &tsk->posix_cputimers;
1052 struct signal_struct *sig;
1053
1054 if (!expiry_cache_is_inactive(pct)) {
1055 u64 samples[CPUCLOCK_MAX];
1056
1057 task_sample_cputime(tsk, samples);
1058 if (task_cputimers_expired(samples, pct))
1059 return true;
1060 }
1061
1062 sig = tsk->signal;
1063 pct = &sig->posix_cputimers;
1064 /*
1065 * Check if thread group timers expired when timers are active and
1066 * no other thread in the group is already handling expiry for
1067 * thread group cputimers. These fields are read without the
1068 * sighand lock. However, this is fine because this is meant to be
1069 * a fastpath heuristic to determine whether we should try to
1070 * acquire the sighand lock to handle timer expiry.
1071 *
1072 * In the worst case scenario, if concurrently timers_active is set
1073 * or expiry_active is cleared, but the current thread doesn't see
1074 * the change yet, the timer checks are delayed until the next
1075 * thread in the group gets a scheduler interrupt to handle the
1076 * timer. This isn't an issue in practice because these types of
1077 * delays with signals actually getting sent are expected.
1078 */
1079 if (READ_ONCE(pct->timers_active) && !READ_ONCE(pct->expiry_active)) {
1080 u64 samples[CPUCLOCK_MAX];
1081
1082 proc_sample_cputime_atomic(&sig->cputimer.cputime_atomic,
1083 samples);
1084
1085 if (task_cputimers_expired(samples, pct))
1086 return true;
1087 }
1088
1089 if (dl_task(tsk) && tsk->dl.dl_overrun)
1090 return true;
1091
1092 return false;
1093}
1094
1095static void handle_posix_cpu_timers(struct task_struct *tsk);
1096
1097#ifdef CONFIG_POSIX_CPU_TIMERS_TASK_WORK
1098static void posix_cpu_timers_work(struct callback_head *work)
1099{
1100 handle_posix_cpu_timers(current);
1101}
1102
1103/*
1104 * Initialize posix CPU timers task work in init task. Out of line to
1105 * keep the callback static and to avoid header recursion hell.
1106 */
1107void __init posix_cputimers_init_work(void)
1108{
1109 init_task_work(¤t->posix_cputimers_work.work,
1110 posix_cpu_timers_work);
1111}
1112
1113/*
1114 * Note: All operations on tsk->posix_cputimer_work.scheduled happen either
1115 * in hard interrupt context or in task context with interrupts
1116 * disabled. Aside of that the writer/reader interaction is always in the
1117 * context of the current task, which means they are strict per CPU.
1118 */
1119static inline bool posix_cpu_timers_work_scheduled(struct task_struct *tsk)
1120{
1121 return tsk->posix_cputimers_work.scheduled;
1122}
1123
1124static inline void __run_posix_cpu_timers(struct task_struct *tsk)
1125{
1126 if (WARN_ON_ONCE(tsk->posix_cputimers_work.scheduled))
1127 return;
1128
1129 /* Schedule task work to actually expire the timers */
1130 tsk->posix_cputimers_work.scheduled = true;
1131 task_work_add(tsk, &tsk->posix_cputimers_work.work, TWA_RESUME);
1132}
1133
1134static inline bool posix_cpu_timers_enable_work(struct task_struct *tsk,
1135 unsigned long start)
1136{
1137 bool ret = true;
1138
1139 /*
1140 * On !RT kernels interrupts are disabled while collecting expired
1141 * timers, so no tick can happen and the fast path check can be
1142 * reenabled without further checks.
1143 */
1144 if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
1145 tsk->posix_cputimers_work.scheduled = false;
1146 return true;
1147 }
1148
1149 /*
1150 * On RT enabled kernels ticks can happen while the expired timers
1151 * are collected under sighand lock. But any tick which observes
1152 * the CPUTIMERS_WORK_SCHEDULED bit set, does not run the fastpath
1153 * checks. So reenabling the tick work has do be done carefully:
1154 *
1155 * Disable interrupts and run the fast path check if jiffies have
1156 * advanced since the collecting of expired timers started. If
1157 * jiffies have not advanced or the fast path check did not find
1158 * newly expired timers, reenable the fast path check in the timer
1159 * interrupt. If there are newly expired timers, return false and
1160 * let the collection loop repeat.
1161 */
1162 local_irq_disable();
1163 if (start != jiffies && fastpath_timer_check(tsk))
1164 ret = false;
1165 else
1166 tsk->posix_cputimers_work.scheduled = false;
1167 local_irq_enable();
1168
1169 return ret;
1170}
1171#else /* CONFIG_POSIX_CPU_TIMERS_TASK_WORK */
1172static inline void __run_posix_cpu_timers(struct task_struct *tsk)
1173{
1174 lockdep_posixtimer_enter();
1175 handle_posix_cpu_timers(tsk);
1176 lockdep_posixtimer_exit();
1177}
1178
1179static inline bool posix_cpu_timers_work_scheduled(struct task_struct *tsk)
1180{
1181 return false;
1182}
1183
1184static inline bool posix_cpu_timers_enable_work(struct task_struct *tsk,
1185 unsigned long start)
1186{
1187 return true;
1188}
1189#endif /* CONFIG_POSIX_CPU_TIMERS_TASK_WORK */
1190
1191static void handle_posix_cpu_timers(struct task_struct *tsk)
1192{
1193 struct k_itimer *timer, *next;
1194 unsigned long flags, start;
1195 LIST_HEAD(firing);
1196
1197 if (!lock_task_sighand(tsk, &flags))
1198 return;
1199
1200 do {
1201 /*
1202 * On RT locking sighand lock does not disable interrupts,
1203 * so this needs to be careful vs. ticks. Store the current
1204 * jiffies value.
1205 */
1206 start = READ_ONCE(jiffies);
1207 barrier();
1208
1209 /*
1210 * Here we take off tsk->signal->cpu_timers[N] and
1211 * tsk->cpu_timers[N] all the timers that are firing, and
1212 * put them on the firing list.
1213 */
1214 check_thread_timers(tsk, &firing);
1215
1216 check_process_timers(tsk, &firing);
1217
1218 /*
1219 * The above timer checks have updated the expiry cache and
1220 * because nothing can have queued or modified timers after
1221 * sighand lock was taken above it is guaranteed to be
1222 * consistent. So the next timer interrupt fastpath check
1223 * will find valid data.
1224 *
1225 * If timer expiry runs in the timer interrupt context then
1226 * the loop is not relevant as timers will be directly
1227 * expired in interrupt context. The stub function below
1228 * returns always true which allows the compiler to
1229 * optimize the loop out.
1230 *
1231 * If timer expiry is deferred to task work context then
1232 * the following rules apply:
1233 *
1234 * - On !RT kernels no tick can have happened on this CPU
1235 * after sighand lock was acquired because interrupts are
1236 * disabled. So reenabling task work before dropping
1237 * sighand lock and reenabling interrupts is race free.
1238 *
1239 * - On RT kernels ticks might have happened but the tick
1240 * work ignored posix CPU timer handling because the
1241 * CPUTIMERS_WORK_SCHEDULED bit is set. Reenabling work
1242 * must be done very carefully including a check whether
1243 * ticks have happened since the start of the timer
1244 * expiry checks. posix_cpu_timers_enable_work() takes
1245 * care of that and eventually lets the expiry checks
1246 * run again.
1247 */
1248 } while (!posix_cpu_timers_enable_work(tsk, start));
1249
1250 /*
1251 * We must release sighand lock before taking any timer's lock.
1252 * There is a potential race with timer deletion here, as the
1253 * siglock now protects our private firing list. We have set
1254 * the firing flag in each timer, so that a deletion attempt
1255 * that gets the timer lock before we do will give it up and
1256 * spin until we've taken care of that timer below.
1257 */
1258 unlock_task_sighand(tsk, &flags);
1259
1260 /*
1261 * Now that all the timers on our list have the firing flag,
1262 * no one will touch their list entries but us. We'll take
1263 * each timer's lock before clearing its firing flag, so no
1264 * timer call will interfere.
1265 */
1266 list_for_each_entry_safe(timer, next, &firing, it.cpu.elist) {
1267 int cpu_firing;
1268
1269 /*
1270 * spin_lock() is sufficient here even independent of the
1271 * expiry context. If expiry happens in hard interrupt
1272 * context it's obvious. For task work context it's safe
1273 * because all other operations on timer::it_lock happen in
1274 * task context (syscall or exit).
1275 */
1276 spin_lock(&timer->it_lock);
1277 list_del_init(&timer->it.cpu.elist);
1278 cpu_firing = timer->it.cpu.firing;
1279 timer->it.cpu.firing = 0;
1280 /*
1281 * The firing flag is -1 if we collided with a reset
1282 * of the timer, which already reported this
1283 * almost-firing as an overrun. So don't generate an event.
1284 */
1285 if (likely(cpu_firing >= 0))
1286 cpu_timer_fire(timer);
1287 spin_unlock(&timer->it_lock);
1288 }
1289}
1290
1291/*
1292 * This is called from the timer interrupt handler. The irq handler has
1293 * already updated our counts. We need to check if any timers fire now.
1294 * Interrupts are disabled.
1295 */
1296void run_posix_cpu_timers(void)
1297{
1298 struct task_struct *tsk = current;
1299
1300 lockdep_assert_irqs_disabled();
1301
1302 /*
1303 * If the actual expiry is deferred to task work context and the
1304 * work is already scheduled there is no point to do anything here.
1305 */
1306 if (posix_cpu_timers_work_scheduled(tsk))
1307 return;
1308
1309 /*
1310 * The fast path checks that there are no expired thread or thread
1311 * group timers. If that's so, just return.
1312 */
1313 if (!fastpath_timer_check(tsk))
1314 return;
1315
1316 __run_posix_cpu_timers(tsk);
1317}
1318
1319/*
1320 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1321 * The tsk->sighand->siglock must be held by the caller.
1322 */
1323void set_process_cpu_timer(struct task_struct *tsk, unsigned int clkid,
1324 u64 *newval, u64 *oldval)
1325{
1326 u64 now, *nextevt;
1327
1328 if (WARN_ON_ONCE(clkid >= CPUCLOCK_SCHED))
1329 return;
1330
1331 nextevt = &tsk->signal->posix_cputimers.bases[clkid].nextevt;
1332 now = cpu_clock_sample_group(clkid, tsk, true);
1333
1334 if (oldval) {
1335 /*
1336 * We are setting itimer. The *oldval is absolute and we update
1337 * it to be relative, *newval argument is relative and we update
1338 * it to be absolute.
1339 */
1340 if (*oldval) {
1341 if (*oldval <= now) {
1342 /* Just about to fire. */
1343 *oldval = TICK_NSEC;
1344 } else {
1345 *oldval -= now;
1346 }
1347 }
1348
1349 if (!*newval)
1350 return;
1351 *newval += now;
1352 }
1353
1354 /*
1355 * Update expiration cache if this is the earliest timer. CPUCLOCK_PROF
1356 * expiry cache is also used by RLIMIT_CPU!.
1357 */
1358 if (*newval < *nextevt)
1359 *nextevt = *newval;
1360
1361 tick_dep_set_signal(tsk, TICK_DEP_BIT_POSIX_TIMER);
1362}
1363
1364static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1365 const struct timespec64 *rqtp)
1366{
1367 struct itimerspec64 it;
1368 struct k_itimer timer;
1369 u64 expires;
1370 int error;
1371
1372 /*
1373 * Set up a temporary timer and then wait for it to go off.
1374 */
1375 memset(&timer, 0, sizeof timer);
1376 spin_lock_init(&timer.it_lock);
1377 timer.it_clock = which_clock;
1378 timer.it_overrun = -1;
1379 error = posix_cpu_timer_create(&timer);
1380 timer.it_process = current;
1381
1382 if (!error) {
1383 static struct itimerspec64 zero_it;
1384 struct restart_block *restart;
1385
1386 memset(&it, 0, sizeof(it));
1387 it.it_value = *rqtp;
1388
1389 spin_lock_irq(&timer.it_lock);
1390 error = posix_cpu_timer_set(&timer, flags, &it, NULL);
1391 if (error) {
1392 spin_unlock_irq(&timer.it_lock);
1393 return error;
1394 }
1395
1396 while (!signal_pending(current)) {
1397 if (!cpu_timer_getexpires(&timer.it.cpu)) {
1398 /*
1399 * Our timer fired and was reset, below
1400 * deletion can not fail.
1401 */
1402 posix_cpu_timer_del(&timer);
1403 spin_unlock_irq(&timer.it_lock);
1404 return 0;
1405 }
1406
1407 /*
1408 * Block until cpu_timer_fire (or a signal) wakes us.
1409 */
1410 __set_current_state(TASK_INTERRUPTIBLE);
1411 spin_unlock_irq(&timer.it_lock);
1412 schedule();
1413 spin_lock_irq(&timer.it_lock);
1414 }
1415
1416 /*
1417 * We were interrupted by a signal.
1418 */
1419 expires = cpu_timer_getexpires(&timer.it.cpu);
1420 error = posix_cpu_timer_set(&timer, 0, &zero_it, &it);
1421 if (!error) {
1422 /*
1423 * Timer is now unarmed, deletion can not fail.
1424 */
1425 posix_cpu_timer_del(&timer);
1426 }
1427 spin_unlock_irq(&timer.it_lock);
1428
1429 while (error == TIMER_RETRY) {
1430 /*
1431 * We need to handle case when timer was or is in the
1432 * middle of firing. In other cases we already freed
1433 * resources.
1434 */
1435 spin_lock_irq(&timer.it_lock);
1436 error = posix_cpu_timer_del(&timer);
1437 spin_unlock_irq(&timer.it_lock);
1438 }
1439
1440 if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
1441 /*
1442 * It actually did fire already.
1443 */
1444 return 0;
1445 }
1446
1447 error = -ERESTART_RESTARTBLOCK;
1448 /*
1449 * Report back to the user the time still remaining.
1450 */
1451 restart = ¤t->restart_block;
1452 restart->nanosleep.expires = expires;
1453 if (restart->nanosleep.type != TT_NONE)
1454 error = nanosleep_copyout(restart, &it.it_value);
1455 }
1456
1457 return error;
1458}
1459
1460static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1461
1462static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1463 const struct timespec64 *rqtp)
1464{
1465 struct restart_block *restart_block = ¤t->restart_block;
1466 int error;
1467
1468 /*
1469 * Diagnose required errors first.
1470 */
1471 if (CPUCLOCK_PERTHREAD(which_clock) &&
1472 (CPUCLOCK_PID(which_clock) == 0 ||
1473 CPUCLOCK_PID(which_clock) == task_pid_vnr(current)))
1474 return -EINVAL;
1475
1476 error = do_cpu_nanosleep(which_clock, flags, rqtp);
1477
1478 if (error == -ERESTART_RESTARTBLOCK) {
1479
1480 if (flags & TIMER_ABSTIME)
1481 return -ERESTARTNOHAND;
1482
1483 restart_block->nanosleep.clockid = which_clock;
1484 set_restart_fn(restart_block, posix_cpu_nsleep_restart);
1485 }
1486 return error;
1487}
1488
1489static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1490{
1491 clockid_t which_clock = restart_block->nanosleep.clockid;
1492 struct timespec64 t;
1493
1494 t = ns_to_timespec64(restart_block->nanosleep.expires);
1495
1496 return do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t);
1497}
1498
1499#define PROCESS_CLOCK make_process_cpuclock(0, CPUCLOCK_SCHED)
1500#define THREAD_CLOCK make_thread_cpuclock(0, CPUCLOCK_SCHED)
1501
1502static int process_cpu_clock_getres(const clockid_t which_clock,
1503 struct timespec64 *tp)
1504{
1505 return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1506}
1507static int process_cpu_clock_get(const clockid_t which_clock,
1508 struct timespec64 *tp)
1509{
1510 return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1511}
1512static int process_cpu_timer_create(struct k_itimer *timer)
1513{
1514 timer->it_clock = PROCESS_CLOCK;
1515 return posix_cpu_timer_create(timer);
1516}
1517static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1518 const struct timespec64 *rqtp)
1519{
1520 return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp);
1521}
1522static int thread_cpu_clock_getres(const clockid_t which_clock,
1523 struct timespec64 *tp)
1524{
1525 return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1526}
1527static int thread_cpu_clock_get(const clockid_t which_clock,
1528 struct timespec64 *tp)
1529{
1530 return posix_cpu_clock_get(THREAD_CLOCK, tp);
1531}
1532static int thread_cpu_timer_create(struct k_itimer *timer)
1533{
1534 timer->it_clock = THREAD_CLOCK;
1535 return posix_cpu_timer_create(timer);
1536}
1537
1538const struct k_clock clock_posix_cpu = {
1539 .clock_getres = posix_cpu_clock_getres,
1540 .clock_set = posix_cpu_clock_set,
1541 .clock_get_timespec = posix_cpu_clock_get,
1542 .timer_create = posix_cpu_timer_create,
1543 .nsleep = posix_cpu_nsleep,
1544 .timer_set = posix_cpu_timer_set,
1545 .timer_del = posix_cpu_timer_del,
1546 .timer_get = posix_cpu_timer_get,
1547 .timer_rearm = posix_cpu_timer_rearm,
1548};
1549
1550const struct k_clock clock_process = {
1551 .clock_getres = process_cpu_clock_getres,
1552 .clock_get_timespec = process_cpu_clock_get,
1553 .timer_create = process_cpu_timer_create,
1554 .nsleep = process_cpu_nsleep,
1555};
1556
1557const struct k_clock clock_thread = {
1558 .clock_getres = thread_cpu_clock_getres,
1559 .clock_get_timespec = thread_cpu_clock_get,
1560 .timer_create = thread_cpu_timer_create,
1561};