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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
199static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
200{
201 if (b->utime > a->utime)
202 a->utime = b->utime;
203
204 if (b->stime > a->stime)
205 a->stime = b->stime;
206
207 if (b->sum_exec_runtime > a->sum_exec_runtime)
208 a->sum_exec_runtime = b->sum_exec_runtime;
209}
210
211void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
212{
213 struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
214 struct task_cputime sum;
215 unsigned long flags;
216
217 if (!cputimer->running) {
218 /*
219 * The POSIX timer interface allows for absolute time expiry
220 * values through the TIMER_ABSTIME flag, therefore we have
221 * to synchronize the timer to the clock every time we start
222 * it.
223 */
224 thread_group_cputime(tsk, &sum);
225 raw_spin_lock_irqsave(&cputimer->lock, flags);
226 cputimer->running = 1;
227 update_gt_cputime(&cputimer->cputime, &sum);
228 } else
229 raw_spin_lock_irqsave(&cputimer->lock, flags);
230 *times = cputimer->cputime;
231 raw_spin_unlock_irqrestore(&cputimer->lock, flags);
232}
233
234/*
235 * Sample a process (thread group) clock for the given group_leader task.
236 * Must be called with task sighand lock held for safe while_each_thread()
237 * traversal.
238 */
239static int cpu_clock_sample_group(const clockid_t which_clock,
240 struct task_struct *p,
241 unsigned long long *sample)
242{
243 struct task_cputime cputime;
244
245 switch (CPUCLOCK_WHICH(which_clock)) {
246 default:
247 return -EINVAL;
248 case CPUCLOCK_PROF:
249 thread_group_cputime(p, &cputime);
250 *sample = cputime_to_expires(cputime.utime + cputime.stime);
251 break;
252 case CPUCLOCK_VIRT:
253 thread_group_cputime(p, &cputime);
254 *sample = cputime_to_expires(cputime.utime);
255 break;
256 case CPUCLOCK_SCHED:
257 thread_group_cputime(p, &cputime);
258 *sample = cputime.sum_exec_runtime;
259 break;
260 }
261 return 0;
262}
263
264static int posix_cpu_clock_get_task(struct task_struct *tsk,
265 const clockid_t which_clock,
266 struct timespec *tp)
267{
268 int err = -EINVAL;
269 unsigned long long rtn;
270
271 if (CPUCLOCK_PERTHREAD(which_clock)) {
272 if (same_thread_group(tsk, current))
273 err = cpu_clock_sample(which_clock, tsk, &rtn);
274 } else {
275 unsigned long flags;
276 struct sighand_struct *sighand;
277
278 /*
279 * while_each_thread() is not yet entirely RCU safe,
280 * keep locking the group while sampling process
281 * clock for now.
282 */
283 sighand = lock_task_sighand(tsk, &flags);
284 if (!sighand)
285 return err;
286
287 if (tsk == current || thread_group_leader(tsk))
288 err = cpu_clock_sample_group(which_clock, tsk, &rtn);
289
290 unlock_task_sighand(tsk, &flags);
291 }
292
293 if (!err)
294 sample_to_timespec(which_clock, rtn, tp);
295
296 return err;
297}
298
299
300static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
301{
302 const pid_t pid = CPUCLOCK_PID(which_clock);
303 int err = -EINVAL;
304
305 if (pid == 0) {
306 /*
307 * Special case constant value for our own clocks.
308 * We don't have to do any lookup to find ourselves.
309 */
310 err = posix_cpu_clock_get_task(current, which_clock, tp);
311 } else {
312 /*
313 * Find the given PID, and validate that the caller
314 * should be able to see it.
315 */
316 struct task_struct *p;
317 rcu_read_lock();
318 p = find_task_by_vpid(pid);
319 if (p)
320 err = posix_cpu_clock_get_task(p, which_clock, tp);
321 rcu_read_unlock();
322 }
323
324 return err;
325}
326
327
328/*
329 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
330 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
331 * new timer already all-zeros initialized.
332 */
333static int posix_cpu_timer_create(struct k_itimer *new_timer)
334{
335 int ret = 0;
336 const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
337 struct task_struct *p;
338
339 if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
340 return -EINVAL;
341
342 INIT_LIST_HEAD(&new_timer->it.cpu.entry);
343
344 rcu_read_lock();
345 if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
346 if (pid == 0) {
347 p = current;
348 } else {
349 p = find_task_by_vpid(pid);
350 if (p && !same_thread_group(p, current))
351 p = NULL;
352 }
353 } else {
354 if (pid == 0) {
355 p = current->group_leader;
356 } else {
357 p = find_task_by_vpid(pid);
358 if (p && !has_group_leader_pid(p))
359 p = NULL;
360 }
361 }
362 new_timer->it.cpu.task = p;
363 if (p) {
364 get_task_struct(p);
365 } else {
366 ret = -EINVAL;
367 }
368 rcu_read_unlock();
369
370 return ret;
371}
372
373/*
374 * Clean up a CPU-clock timer that is about to be destroyed.
375 * This is called from timer deletion with the timer already locked.
376 * If we return TIMER_RETRY, it's necessary to release the timer's lock
377 * and try again. (This happens when the timer is in the middle of firing.)
378 */
379static int posix_cpu_timer_del(struct k_itimer *timer)
380{
381 int ret = 0;
382 unsigned long flags;
383 struct sighand_struct *sighand;
384 struct task_struct *p = timer->it.cpu.task;
385
386 WARN_ON_ONCE(p == NULL);
387
388 /*
389 * Protect against sighand release/switch in exit/exec and process/
390 * thread timer list entry concurrent read/writes.
391 */
392 sighand = lock_task_sighand(p, &flags);
393 if (unlikely(sighand == NULL)) {
394 /*
395 * We raced with the reaping of the task.
396 * The deletion should have cleared us off the list.
397 */
398 WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry));
399 } else {
400 if (timer->it.cpu.firing)
401 ret = TIMER_RETRY;
402 else
403 list_del(&timer->it.cpu.entry);
404
405 unlock_task_sighand(p, &flags);
406 }
407
408 if (!ret)
409 put_task_struct(p);
410
411 return ret;
412}
413
414static void cleanup_timers_list(struct list_head *head)
415{
416 struct cpu_timer_list *timer, *next;
417
418 list_for_each_entry_safe(timer, next, head, entry)
419 list_del_init(&timer->entry);
420}
421
422/*
423 * Clean out CPU timers still ticking when a thread exited. The task
424 * pointer is cleared, and the expiry time is replaced with the residual
425 * time for later timer_gettime calls to return.
426 * This must be called with the siglock held.
427 */
428static void cleanup_timers(struct list_head *head)
429{
430 cleanup_timers_list(head);
431 cleanup_timers_list(++head);
432 cleanup_timers_list(++head);
433}
434
435/*
436 * These are both called with the siglock held, when the current thread
437 * is being reaped. When the final (leader) thread in the group is reaped,
438 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
439 */
440void posix_cpu_timers_exit(struct task_struct *tsk)
441{
442 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
443 sizeof(unsigned long long));
444 cleanup_timers(tsk->cpu_timers);
445
446}
447void posix_cpu_timers_exit_group(struct task_struct *tsk)
448{
449 cleanup_timers(tsk->signal->cpu_timers);
450}
451
452static inline int expires_gt(cputime_t expires, cputime_t new_exp)
453{
454 return expires == 0 || expires > new_exp;
455}
456
457/*
458 * Insert the timer on the appropriate list before any timers that
459 * expire later. This must be called with the sighand lock held.
460 */
461static void arm_timer(struct k_itimer *timer)
462{
463 struct task_struct *p = timer->it.cpu.task;
464 struct list_head *head, *listpos;
465 struct task_cputime *cputime_expires;
466 struct cpu_timer_list *const nt = &timer->it.cpu;
467 struct cpu_timer_list *next;
468
469 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
470 head = p->cpu_timers;
471 cputime_expires = &p->cputime_expires;
472 } else {
473 head = p->signal->cpu_timers;
474 cputime_expires = &p->signal->cputime_expires;
475 }
476 head += CPUCLOCK_WHICH(timer->it_clock);
477
478 listpos = head;
479 list_for_each_entry(next, head, entry) {
480 if (nt->expires < next->expires)
481 break;
482 listpos = &next->entry;
483 }
484 list_add(&nt->entry, listpos);
485
486 if (listpos == head) {
487 unsigned long long exp = nt->expires;
488
489 /*
490 * We are the new earliest-expiring POSIX 1.b timer, hence
491 * need to update expiration cache. Take into account that
492 * for process timers we share expiration cache with itimers
493 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
494 */
495
496 switch (CPUCLOCK_WHICH(timer->it_clock)) {
497 case CPUCLOCK_PROF:
498 if (expires_gt(cputime_expires->prof_exp, expires_to_cputime(exp)))
499 cputime_expires->prof_exp = expires_to_cputime(exp);
500 break;
501 case CPUCLOCK_VIRT:
502 if (expires_gt(cputime_expires->virt_exp, expires_to_cputime(exp)))
503 cputime_expires->virt_exp = expires_to_cputime(exp);
504 break;
505 case CPUCLOCK_SCHED:
506 if (cputime_expires->sched_exp == 0 ||
507 cputime_expires->sched_exp > exp)
508 cputime_expires->sched_exp = exp;
509 break;
510 }
511 }
512}
513
514/*
515 * The timer is locked, fire it and arrange for its reload.
516 */
517static void cpu_timer_fire(struct k_itimer *timer)
518{
519 if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
520 /*
521 * User don't want any signal.
522 */
523 timer->it.cpu.expires = 0;
524 } else if (unlikely(timer->sigq == NULL)) {
525 /*
526 * This a special case for clock_nanosleep,
527 * not a normal timer from sys_timer_create.
528 */
529 wake_up_process(timer->it_process);
530 timer->it.cpu.expires = 0;
531 } else if (timer->it.cpu.incr == 0) {
532 /*
533 * One-shot timer. Clear it as soon as it's fired.
534 */
535 posix_timer_event(timer, 0);
536 timer->it.cpu.expires = 0;
537 } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
538 /*
539 * The signal did not get queued because the signal
540 * was ignored, so we won't get any callback to
541 * reload the timer. But we need to keep it
542 * ticking in case the signal is deliverable next time.
543 */
544 posix_cpu_timer_schedule(timer);
545 }
546}
547
548/*
549 * Sample a process (thread group) timer for the given group_leader task.
550 * Must be called with task sighand lock held for safe while_each_thread()
551 * traversal.
552 */
553static int cpu_timer_sample_group(const clockid_t which_clock,
554 struct task_struct *p,
555 unsigned long long *sample)
556{
557 struct task_cputime cputime;
558
559 thread_group_cputimer(p, &cputime);
560 switch (CPUCLOCK_WHICH(which_clock)) {
561 default:
562 return -EINVAL;
563 case CPUCLOCK_PROF:
564 *sample = cputime_to_expires(cputime.utime + cputime.stime);
565 break;
566 case CPUCLOCK_VIRT:
567 *sample = cputime_to_expires(cputime.utime);
568 break;
569 case CPUCLOCK_SCHED:
570 *sample = cputime.sum_exec_runtime + task_delta_exec(p);
571 break;
572 }
573 return 0;
574}
575
576#ifdef CONFIG_NO_HZ_FULL
577static void nohz_kick_work_fn(struct work_struct *work)
578{
579 tick_nohz_full_kick_all();
580}
581
582static DECLARE_WORK(nohz_kick_work, nohz_kick_work_fn);
583
584/*
585 * We need the IPIs to be sent from sane process context.
586 * The posix cpu timers are always set with irqs disabled.
587 */
588static void posix_cpu_timer_kick_nohz(void)
589{
590 if (context_tracking_is_enabled())
591 schedule_work(&nohz_kick_work);
592}
593
594bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk)
595{
596 if (!task_cputime_zero(&tsk->cputime_expires))
597 return false;
598
599 if (tsk->signal->cputimer.running)
600 return false;
601
602 return true;
603}
604#else
605static inline void posix_cpu_timer_kick_nohz(void) { }
606#endif
607
608/*
609 * Guts of sys_timer_settime for CPU timers.
610 * This is called with the timer locked and interrupts disabled.
611 * If we return TIMER_RETRY, it's necessary to release the timer's lock
612 * and try again. (This happens when the timer is in the middle of firing.)
613 */
614static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
615 struct itimerspec *new, struct itimerspec *old)
616{
617 unsigned long flags;
618 struct sighand_struct *sighand;
619 struct task_struct *p = timer->it.cpu.task;
620 unsigned long long old_expires, new_expires, old_incr, val;
621 int ret;
622
623 WARN_ON_ONCE(p == NULL);
624
625 new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
626
627 /*
628 * Protect against sighand release/switch in exit/exec and p->cpu_timers
629 * and p->signal->cpu_timers read/write in arm_timer()
630 */
631 sighand = lock_task_sighand(p, &flags);
632 /*
633 * If p has just been reaped, we can no
634 * longer get any information about it at all.
635 */
636 if (unlikely(sighand == NULL)) {
637 return -ESRCH;
638 }
639
640 /*
641 * Disarm any old timer after extracting its expiry time.
642 */
643 WARN_ON_ONCE(!irqs_disabled());
644
645 ret = 0;
646 old_incr = timer->it.cpu.incr;
647 old_expires = timer->it.cpu.expires;
648 if (unlikely(timer->it.cpu.firing)) {
649 timer->it.cpu.firing = -1;
650 ret = TIMER_RETRY;
651 } else
652 list_del_init(&timer->it.cpu.entry);
653
654 /*
655 * We need to sample the current value to convert the new
656 * value from to relative and absolute, and to convert the
657 * old value from absolute to relative. To set a process
658 * timer, we need a sample to balance the thread expiry
659 * times (in arm_timer). With an absolute time, we must
660 * check if it's already passed. In short, we need a sample.
661 */
662 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
663 cpu_clock_sample(timer->it_clock, p, &val);
664 } else {
665 cpu_timer_sample_group(timer->it_clock, p, &val);
666 }
667
668 if (old) {
669 if (old_expires == 0) {
670 old->it_value.tv_sec = 0;
671 old->it_value.tv_nsec = 0;
672 } else {
673 /*
674 * Update the timer in case it has
675 * overrun already. If it has,
676 * we'll report it as having overrun
677 * and with the next reloaded timer
678 * already ticking, though we are
679 * swallowing that pending
680 * notification here to install the
681 * new setting.
682 */
683 bump_cpu_timer(timer, val);
684 if (val < timer->it.cpu.expires) {
685 old_expires = timer->it.cpu.expires - val;
686 sample_to_timespec(timer->it_clock,
687 old_expires,
688 &old->it_value);
689 } else {
690 old->it_value.tv_nsec = 1;
691 old->it_value.tv_sec = 0;
692 }
693 }
694 }
695
696 if (unlikely(ret)) {
697 /*
698 * We are colliding with the timer actually firing.
699 * Punt after filling in the timer's old value, and
700 * disable this firing since we are already reporting
701 * it as an overrun (thanks to bump_cpu_timer above).
702 */
703 unlock_task_sighand(p, &flags);
704 goto out;
705 }
706
707 if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) {
708 new_expires += val;
709 }
710
711 /*
712 * Install the new expiry time (or zero).
713 * For a timer with no notification action, we don't actually
714 * arm the timer (we'll just fake it for timer_gettime).
715 */
716 timer->it.cpu.expires = new_expires;
717 if (new_expires != 0 && val < new_expires) {
718 arm_timer(timer);
719 }
720
721 unlock_task_sighand(p, &flags);
722 /*
723 * Install the new reload setting, and
724 * set up the signal and overrun bookkeeping.
725 */
726 timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
727 &new->it_interval);
728
729 /*
730 * This acts as a modification timestamp for the timer,
731 * so any automatic reload attempt will punt on seeing
732 * that we have reset the timer manually.
733 */
734 timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
735 ~REQUEUE_PENDING;
736 timer->it_overrun_last = 0;
737 timer->it_overrun = -1;
738
739 if (new_expires != 0 && !(val < new_expires)) {
740 /*
741 * The designated time already passed, so we notify
742 * immediately, even if the thread never runs to
743 * accumulate more time on this clock.
744 */
745 cpu_timer_fire(timer);
746 }
747
748 ret = 0;
749 out:
750 if (old) {
751 sample_to_timespec(timer->it_clock,
752 old_incr, &old->it_interval);
753 }
754 if (!ret)
755 posix_cpu_timer_kick_nohz();
756 return ret;
757}
758
759static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
760{
761 unsigned long long now;
762 struct task_struct *p = timer->it.cpu.task;
763
764 WARN_ON_ONCE(p == NULL);
765
766 /*
767 * Easy part: convert the reload time.
768 */
769 sample_to_timespec(timer->it_clock,
770 timer->it.cpu.incr, &itp->it_interval);
771
772 if (timer->it.cpu.expires == 0) { /* Timer not armed at all. */
773 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
774 return;
775 }
776
777 /*
778 * Sample the clock to take the difference with the expiry time.
779 */
780 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
781 cpu_clock_sample(timer->it_clock, p, &now);
782 } else {
783 struct sighand_struct *sighand;
784 unsigned long flags;
785
786 /*
787 * Protect against sighand release/switch in exit/exec and
788 * also make timer sampling safe if it ends up calling
789 * thread_group_cputime().
790 */
791 sighand = lock_task_sighand(p, &flags);
792 if (unlikely(sighand == NULL)) {
793 /*
794 * The process has been reaped.
795 * We can't even collect a sample any more.
796 * Call the timer disarmed, nothing else to do.
797 */
798 timer->it.cpu.expires = 0;
799 sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
800 &itp->it_value);
801 } else {
802 cpu_timer_sample_group(timer->it_clock, p, &now);
803 unlock_task_sighand(p, &flags);
804 }
805 }
806
807 if (now < timer->it.cpu.expires) {
808 sample_to_timespec(timer->it_clock,
809 timer->it.cpu.expires - now,
810 &itp->it_value);
811 } else {
812 /*
813 * The timer should have expired already, but the firing
814 * hasn't taken place yet. Say it's just about to expire.
815 */
816 itp->it_value.tv_nsec = 1;
817 itp->it_value.tv_sec = 0;
818 }
819}
820
821static unsigned long long
822check_timers_list(struct list_head *timers,
823 struct list_head *firing,
824 unsigned long long curr)
825{
826 int maxfire = 20;
827
828 while (!list_empty(timers)) {
829 struct cpu_timer_list *t;
830
831 t = list_first_entry(timers, struct cpu_timer_list, entry);
832
833 if (!--maxfire || curr < t->expires)
834 return t->expires;
835
836 t->firing = 1;
837 list_move_tail(&t->entry, firing);
838 }
839
840 return 0;
841}
842
843/*
844 * Check for any per-thread CPU timers that have fired and move them off
845 * the tsk->cpu_timers[N] list onto the firing list. Here we update the
846 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
847 */
848static void check_thread_timers(struct task_struct *tsk,
849 struct list_head *firing)
850{
851 struct list_head *timers = tsk->cpu_timers;
852 struct signal_struct *const sig = tsk->signal;
853 struct task_cputime *tsk_expires = &tsk->cputime_expires;
854 unsigned long long expires;
855 unsigned long soft;
856
857 expires = check_timers_list(timers, firing, prof_ticks(tsk));
858 tsk_expires->prof_exp = expires_to_cputime(expires);
859
860 expires = check_timers_list(++timers, firing, virt_ticks(tsk));
861 tsk_expires->virt_exp = expires_to_cputime(expires);
862
863 tsk_expires->sched_exp = check_timers_list(++timers, firing,
864 tsk->se.sum_exec_runtime);
865
866 /*
867 * Check for the special case thread timers.
868 */
869 soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
870 if (soft != RLIM_INFINITY) {
871 unsigned long hard =
872 ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
873
874 if (hard != RLIM_INFINITY &&
875 tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
876 /*
877 * At the hard limit, we just die.
878 * No need to calculate anything else now.
879 */
880 __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
881 return;
882 }
883 if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
884 /*
885 * At the soft limit, send a SIGXCPU every second.
886 */
887 if (soft < hard) {
888 soft += USEC_PER_SEC;
889 sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
890 }
891 printk(KERN_INFO
892 "RT Watchdog Timeout: %s[%d]\n",
893 tsk->comm, task_pid_nr(tsk));
894 __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
895 }
896 }
897}
898
899static void stop_process_timers(struct signal_struct *sig)
900{
901 struct thread_group_cputimer *cputimer = &sig->cputimer;
902 unsigned long flags;
903
904 raw_spin_lock_irqsave(&cputimer->lock, flags);
905 cputimer->running = 0;
906 raw_spin_unlock_irqrestore(&cputimer->lock, flags);
907}
908
909static u32 onecputick;
910
911static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
912 unsigned long long *expires,
913 unsigned long long cur_time, int signo)
914{
915 if (!it->expires)
916 return;
917
918 if (cur_time >= it->expires) {
919 if (it->incr) {
920 it->expires += it->incr;
921 it->error += it->incr_error;
922 if (it->error >= onecputick) {
923 it->expires -= cputime_one_jiffy;
924 it->error -= onecputick;
925 }
926 } else {
927 it->expires = 0;
928 }
929
930 trace_itimer_expire(signo == SIGPROF ?
931 ITIMER_PROF : ITIMER_VIRTUAL,
932 tsk->signal->leader_pid, cur_time);
933 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
934 }
935
936 if (it->expires && (!*expires || it->expires < *expires)) {
937 *expires = it->expires;
938 }
939}
940
941/*
942 * Check for any per-thread CPU timers that have fired and move them
943 * off the tsk->*_timers list onto the firing list. Per-thread timers
944 * have already been taken off.
945 */
946static void check_process_timers(struct task_struct *tsk,
947 struct list_head *firing)
948{
949 struct signal_struct *const sig = tsk->signal;
950 unsigned long long utime, ptime, virt_expires, prof_expires;
951 unsigned long long sum_sched_runtime, sched_expires;
952 struct list_head *timers = sig->cpu_timers;
953 struct task_cputime cputime;
954 unsigned long soft;
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 = ACCESS_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 ACCESS_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
1012/*
1013 * This is called from the signal code (via do_schedule_next_timer)
1014 * when the last timer signal was delivered and we have to reload the timer.
1015 */
1016void posix_cpu_timer_schedule(struct k_itimer *timer)
1017{
1018 struct sighand_struct *sighand;
1019 unsigned long flags;
1020 struct task_struct *p = timer->it.cpu.task;
1021 unsigned long long now;
1022
1023 WARN_ON_ONCE(p == NULL);
1024
1025 /*
1026 * Fetch the current sample and update the timer's expiry time.
1027 */
1028 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1029 cpu_clock_sample(timer->it_clock, p, &now);
1030 bump_cpu_timer(timer, now);
1031 if (unlikely(p->exit_state))
1032 goto out;
1033
1034 /* Protect timer list r/w in arm_timer() */
1035 sighand = lock_task_sighand(p, &flags);
1036 if (!sighand)
1037 goto out;
1038 } else {
1039 /*
1040 * Protect arm_timer() and timer sampling in case of call to
1041 * thread_group_cputime().
1042 */
1043 sighand = lock_task_sighand(p, &flags);
1044 if (unlikely(sighand == NULL)) {
1045 /*
1046 * The process has been reaped.
1047 * We can't even collect a sample any more.
1048 */
1049 timer->it.cpu.expires = 0;
1050 goto out;
1051 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1052 unlock_task_sighand(p, &flags);
1053 /* Optimizations: if the process is dying, no need to rearm */
1054 goto out;
1055 }
1056 cpu_timer_sample_group(timer->it_clock, p, &now);
1057 bump_cpu_timer(timer, now);
1058 /* Leave the sighand locked for the call below. */
1059 }
1060
1061 /*
1062 * Now re-arm for the new expiry time.
1063 */
1064 WARN_ON_ONCE(!irqs_disabled());
1065 arm_timer(timer);
1066 unlock_task_sighand(p, &flags);
1067
1068 /* Kick full dynticks CPUs in case they need to tick on the new timer */
1069 posix_cpu_timer_kick_nohz();
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 cputime_t utime, stime;
1113
1114 task_cputime(tsk, &utime, &stime);
1115
1116 if (!task_cputime_zero(&tsk->cputime_expires)) {
1117 struct task_cputime task_sample = {
1118 .utime = utime,
1119 .stime = stime,
1120 .sum_exec_runtime = tsk->se.sum_exec_runtime
1121 };
1122
1123 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1124 return 1;
1125 }
1126
1127 sig = tsk->signal;
1128 if (sig->cputimer.running) {
1129 struct task_cputime group_sample;
1130
1131 raw_spin_lock(&sig->cputimer.lock);
1132 group_sample = sig->cputimer.cputime;
1133 raw_spin_unlock(&sig->cputimer.lock);
1134
1135 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1136 return 1;
1137 }
1138
1139 return 0;
1140}
1141
1142/*
1143 * This is called from the timer interrupt handler. The irq handler has
1144 * already updated our counts. We need to check if any timers fire now.
1145 * Interrupts are disabled.
1146 */
1147void run_posix_cpu_timers(struct task_struct *tsk)
1148{
1149 LIST_HEAD(firing);
1150 struct k_itimer *timer, *next;
1151 unsigned long flags;
1152
1153 WARN_ON_ONCE(!irqs_disabled());
1154
1155 /*
1156 * The fast path checks that there are no expired thread or thread
1157 * group timers. If that's so, just return.
1158 */
1159 if (!fastpath_timer_check(tsk))
1160 return;
1161
1162 if (!lock_task_sighand(tsk, &flags))
1163 return;
1164 /*
1165 * Here we take off tsk->signal->cpu_timers[N] and
1166 * tsk->cpu_timers[N] all the timers that are firing, and
1167 * put them on the firing list.
1168 */
1169 check_thread_timers(tsk, &firing);
1170 /*
1171 * If there are any active process wide timers (POSIX 1.b, itimers,
1172 * RLIMIT_CPU) cputimer must be running.
1173 */
1174 if (tsk->signal->cputimer.running)
1175 check_process_timers(tsk, &firing);
1176
1177 /*
1178 * We must release these locks before taking any timer's lock.
1179 * There is a potential race with timer deletion here, as the
1180 * siglock now protects our private firing list. We have set
1181 * the firing flag in each timer, so that a deletion attempt
1182 * that gets the timer lock before we do will give it up and
1183 * spin until we've taken care of that timer below.
1184 */
1185 unlock_task_sighand(tsk, &flags);
1186
1187 /*
1188 * Now that all the timers on our list have the firing flag,
1189 * no one will touch their list entries but us. We'll take
1190 * each timer's lock before clearing its firing flag, so no
1191 * timer call will interfere.
1192 */
1193 list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1194 int cpu_firing;
1195
1196 spin_lock(&timer->it_lock);
1197 list_del_init(&timer->it.cpu.entry);
1198 cpu_firing = timer->it.cpu.firing;
1199 timer->it.cpu.firing = 0;
1200 /*
1201 * The firing flag is -1 if we collided with a reset
1202 * of the timer, which already reported this
1203 * almost-firing as an overrun. So don't generate an event.
1204 */
1205 if (likely(cpu_firing >= 0))
1206 cpu_timer_fire(timer);
1207 spin_unlock(&timer->it_lock);
1208 }
1209}
1210
1211/*
1212 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1213 * The tsk->sighand->siglock must be held by the caller.
1214 */
1215void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1216 cputime_t *newval, cputime_t *oldval)
1217{
1218 unsigned long long now;
1219
1220 WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED);
1221 cpu_timer_sample_group(clock_idx, tsk, &now);
1222
1223 if (oldval) {
1224 /*
1225 * We are setting itimer. The *oldval is absolute and we update
1226 * it to be relative, *newval argument is relative and we update
1227 * it to be absolute.
1228 */
1229 if (*oldval) {
1230 if (*oldval <= now) {
1231 /* Just about to fire. */
1232 *oldval = cputime_one_jiffy;
1233 } else {
1234 *oldval -= now;
1235 }
1236 }
1237
1238 if (!*newval)
1239 goto out;
1240 *newval += now;
1241 }
1242
1243 /*
1244 * Update expiration cache if we are the earliest timer, or eventually
1245 * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1246 */
1247 switch (clock_idx) {
1248 case CPUCLOCK_PROF:
1249 if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1250 tsk->signal->cputime_expires.prof_exp = *newval;
1251 break;
1252 case CPUCLOCK_VIRT:
1253 if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1254 tsk->signal->cputime_expires.virt_exp = *newval;
1255 break;
1256 }
1257out:
1258 posix_cpu_timer_kick_nohz();
1259}
1260
1261static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1262 struct timespec *rqtp, struct itimerspec *it)
1263{
1264 struct k_itimer timer;
1265 int error;
1266
1267 /*
1268 * Set up a temporary timer and then wait for it to go off.
1269 */
1270 memset(&timer, 0, sizeof timer);
1271 spin_lock_init(&timer.it_lock);
1272 timer.it_clock = which_clock;
1273 timer.it_overrun = -1;
1274 error = posix_cpu_timer_create(&timer);
1275 timer.it_process = current;
1276 if (!error) {
1277 static struct itimerspec zero_it;
1278
1279 memset(it, 0, sizeof *it);
1280 it->it_value = *rqtp;
1281
1282 spin_lock_irq(&timer.it_lock);
1283 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1284 if (error) {
1285 spin_unlock_irq(&timer.it_lock);
1286 return error;
1287 }
1288
1289 while (!signal_pending(current)) {
1290 if (timer.it.cpu.expires == 0) {
1291 /*
1292 * Our timer fired and was reset, below
1293 * deletion can not fail.
1294 */
1295 posix_cpu_timer_del(&timer);
1296 spin_unlock_irq(&timer.it_lock);
1297 return 0;
1298 }
1299
1300 /*
1301 * Block until cpu_timer_fire (or a signal) wakes us.
1302 */
1303 __set_current_state(TASK_INTERRUPTIBLE);
1304 spin_unlock_irq(&timer.it_lock);
1305 schedule();
1306 spin_lock_irq(&timer.it_lock);
1307 }
1308
1309 /*
1310 * We were interrupted by a signal.
1311 */
1312 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1313 error = posix_cpu_timer_set(&timer, 0, &zero_it, it);
1314 if (!error) {
1315 /*
1316 * Timer is now unarmed, deletion can not fail.
1317 */
1318 posix_cpu_timer_del(&timer);
1319 }
1320 spin_unlock_irq(&timer.it_lock);
1321
1322 while (error == TIMER_RETRY) {
1323 /*
1324 * We need to handle case when timer was or is in the
1325 * middle of firing. In other cases we already freed
1326 * resources.
1327 */
1328 spin_lock_irq(&timer.it_lock);
1329 error = posix_cpu_timer_del(&timer);
1330 spin_unlock_irq(&timer.it_lock);
1331 }
1332
1333 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1334 /*
1335 * It actually did fire already.
1336 */
1337 return 0;
1338 }
1339
1340 error = -ERESTART_RESTARTBLOCK;
1341 }
1342
1343 return error;
1344}
1345
1346static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1347
1348static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1349 struct timespec *rqtp, struct timespec __user *rmtp)
1350{
1351 struct restart_block *restart_block =
1352 ¤t_thread_info()->restart_block;
1353 struct itimerspec it;
1354 int error;
1355
1356 /*
1357 * Diagnose required errors first.
1358 */
1359 if (CPUCLOCK_PERTHREAD(which_clock) &&
1360 (CPUCLOCK_PID(which_clock) == 0 ||
1361 CPUCLOCK_PID(which_clock) == current->pid))
1362 return -EINVAL;
1363
1364 error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1365
1366 if (error == -ERESTART_RESTARTBLOCK) {
1367
1368 if (flags & TIMER_ABSTIME)
1369 return -ERESTARTNOHAND;
1370 /*
1371 * Report back to the user the time still remaining.
1372 */
1373 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1374 return -EFAULT;
1375
1376 restart_block->fn = posix_cpu_nsleep_restart;
1377 restart_block->nanosleep.clockid = which_clock;
1378 restart_block->nanosleep.rmtp = rmtp;
1379 restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1380 }
1381 return error;
1382}
1383
1384static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1385{
1386 clockid_t which_clock = restart_block->nanosleep.clockid;
1387 struct timespec t;
1388 struct itimerspec it;
1389 int error;
1390
1391 t = ns_to_timespec(restart_block->nanosleep.expires);
1392
1393 error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1394
1395 if (error == -ERESTART_RESTARTBLOCK) {
1396 struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1397 /*
1398 * Report back to the user the time still remaining.
1399 */
1400 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1401 return -EFAULT;
1402
1403 restart_block->nanosleep.expires = timespec_to_ns(&t);
1404 }
1405 return error;
1406
1407}
1408
1409#define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1410#define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1411
1412static int process_cpu_clock_getres(const clockid_t which_clock,
1413 struct timespec *tp)
1414{
1415 return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1416}
1417static int process_cpu_clock_get(const clockid_t which_clock,
1418 struct timespec *tp)
1419{
1420 return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1421}
1422static int process_cpu_timer_create(struct k_itimer *timer)
1423{
1424 timer->it_clock = PROCESS_CLOCK;
1425 return posix_cpu_timer_create(timer);
1426}
1427static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1428 struct timespec *rqtp,
1429 struct timespec __user *rmtp)
1430{
1431 return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1432}
1433static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1434{
1435 return -EINVAL;
1436}
1437static int thread_cpu_clock_getres(const clockid_t which_clock,
1438 struct timespec *tp)
1439{
1440 return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1441}
1442static int thread_cpu_clock_get(const clockid_t which_clock,
1443 struct timespec *tp)
1444{
1445 return posix_cpu_clock_get(THREAD_CLOCK, tp);
1446}
1447static int thread_cpu_timer_create(struct k_itimer *timer)
1448{
1449 timer->it_clock = THREAD_CLOCK;
1450 return posix_cpu_timer_create(timer);
1451}
1452
1453struct k_clock clock_posix_cpu = {
1454 .clock_getres = posix_cpu_clock_getres,
1455 .clock_set = posix_cpu_clock_set,
1456 .clock_get = posix_cpu_clock_get,
1457 .timer_create = posix_cpu_timer_create,
1458 .nsleep = posix_cpu_nsleep,
1459 .nsleep_restart = posix_cpu_nsleep_restart,
1460 .timer_set = posix_cpu_timer_set,
1461 .timer_del = posix_cpu_timer_del,
1462 .timer_get = posix_cpu_timer_get,
1463};
1464
1465static __init int init_posix_cpu_timers(void)
1466{
1467 struct k_clock process = {
1468 .clock_getres = process_cpu_clock_getres,
1469 .clock_get = process_cpu_clock_get,
1470 .timer_create = process_cpu_timer_create,
1471 .nsleep = process_cpu_nsleep,
1472 .nsleep_restart = process_cpu_nsleep_restart,
1473 };
1474 struct k_clock thread = {
1475 .clock_getres = thread_cpu_clock_getres,
1476 .clock_get = thread_cpu_clock_get,
1477 .timer_create = thread_cpu_timer_create,
1478 };
1479 struct timespec ts;
1480
1481 posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1482 posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1483
1484 cputime_to_timespec(cputime_one_jiffy, &ts);
1485 onecputick = ts.tv_nsec;
1486 WARN_ON(ts.tv_sec != 0);
1487
1488 return 0;
1489}
1490__initcall(init_posix_cpu_timers);
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
13/*
14 * Called after updating RLIMIT_CPU to run cpu timer and update
15 * tsk->signal->cputime_expires expiration cache if necessary. Needs
16 * siglock protection since other code may update expiration cache as
17 * well.
18 */
19void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
20{
21 cputime_t cputime = secs_to_cputime(rlim_new);
22
23 spin_lock_irq(&task->sighand->siglock);
24 set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
25 spin_unlock_irq(&task->sighand->siglock);
26}
27
28static int check_clock(const clockid_t which_clock)
29{
30 int error = 0;
31 struct task_struct *p;
32 const pid_t pid = CPUCLOCK_PID(which_clock);
33
34 if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
35 return -EINVAL;
36
37 if (pid == 0)
38 return 0;
39
40 rcu_read_lock();
41 p = find_task_by_vpid(pid);
42 if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
43 same_thread_group(p, current) : has_group_leader_pid(p))) {
44 error = -EINVAL;
45 }
46 rcu_read_unlock();
47
48 return error;
49}
50
51static inline union cpu_time_count
52timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
53{
54 union cpu_time_count ret;
55 ret.sched = 0; /* high half always zero when .cpu used */
56 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
57 ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
58 } else {
59 ret.cpu = timespec_to_cputime(tp);
60 }
61 return ret;
62}
63
64static void sample_to_timespec(const clockid_t which_clock,
65 union cpu_time_count cpu,
66 struct timespec *tp)
67{
68 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED)
69 *tp = ns_to_timespec(cpu.sched);
70 else
71 cputime_to_timespec(cpu.cpu, tp);
72}
73
74static inline int cpu_time_before(const clockid_t which_clock,
75 union cpu_time_count now,
76 union cpu_time_count then)
77{
78 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
79 return now.sched < then.sched;
80 } else {
81 return cputime_lt(now.cpu, then.cpu);
82 }
83}
84static inline void cpu_time_add(const clockid_t which_clock,
85 union cpu_time_count *acc,
86 union cpu_time_count val)
87{
88 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
89 acc->sched += val.sched;
90 } else {
91 acc->cpu = cputime_add(acc->cpu, val.cpu);
92 }
93}
94static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
95 union cpu_time_count a,
96 union cpu_time_count b)
97{
98 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
99 a.sched -= b.sched;
100 } else {
101 a.cpu = cputime_sub(a.cpu, b.cpu);
102 }
103 return a;
104}
105
106/*
107 * Divide and limit the result to res >= 1
108 *
109 * This is necessary to prevent signal delivery starvation, when the result of
110 * the division would be rounded down to 0.
111 */
112static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
113{
114 cputime_t res = cputime_div(time, div);
115
116 return max_t(cputime_t, res, 1);
117}
118
119/*
120 * Update expiry time from increment, and increase overrun count,
121 * given the current clock sample.
122 */
123static void bump_cpu_timer(struct k_itimer *timer,
124 union cpu_time_count now)
125{
126 int i;
127
128 if (timer->it.cpu.incr.sched == 0)
129 return;
130
131 if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
132 unsigned long long delta, incr;
133
134 if (now.sched < timer->it.cpu.expires.sched)
135 return;
136 incr = timer->it.cpu.incr.sched;
137 delta = now.sched + incr - timer->it.cpu.expires.sched;
138 /* Don't use (incr*2 < delta), incr*2 might overflow. */
139 for (i = 0; incr < delta - incr; i++)
140 incr = incr << 1;
141 for (; i >= 0; incr >>= 1, i--) {
142 if (delta < incr)
143 continue;
144 timer->it.cpu.expires.sched += incr;
145 timer->it_overrun += 1 << i;
146 delta -= incr;
147 }
148 } else {
149 cputime_t delta, incr;
150
151 if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu))
152 return;
153 incr = timer->it.cpu.incr.cpu;
154 delta = cputime_sub(cputime_add(now.cpu, incr),
155 timer->it.cpu.expires.cpu);
156 /* Don't use (incr*2 < delta), incr*2 might overflow. */
157 for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
158 incr = cputime_add(incr, incr);
159 for (; i >= 0; incr = cputime_halve(incr), i--) {
160 if (cputime_lt(delta, incr))
161 continue;
162 timer->it.cpu.expires.cpu =
163 cputime_add(timer->it.cpu.expires.cpu, incr);
164 timer->it_overrun += 1 << i;
165 delta = cputime_sub(delta, incr);
166 }
167 }
168}
169
170static inline cputime_t prof_ticks(struct task_struct *p)
171{
172 return cputime_add(p->utime, p->stime);
173}
174static inline cputime_t virt_ticks(struct task_struct *p)
175{
176 return p->utime;
177}
178
179static int
180posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
181{
182 int error = check_clock(which_clock);
183 if (!error) {
184 tp->tv_sec = 0;
185 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
186 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
187 /*
188 * If sched_clock is using a cycle counter, we
189 * don't have any idea of its true resolution
190 * exported, but it is much more than 1s/HZ.
191 */
192 tp->tv_nsec = 1;
193 }
194 }
195 return error;
196}
197
198static int
199posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
200{
201 /*
202 * You can never reset a CPU clock, but we check for other errors
203 * in the call before failing with EPERM.
204 */
205 int error = check_clock(which_clock);
206 if (error == 0) {
207 error = -EPERM;
208 }
209 return error;
210}
211
212
213/*
214 * Sample a per-thread clock for the given task.
215 */
216static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
217 union cpu_time_count *cpu)
218{
219 switch (CPUCLOCK_WHICH(which_clock)) {
220 default:
221 return -EINVAL;
222 case CPUCLOCK_PROF:
223 cpu->cpu = prof_ticks(p);
224 break;
225 case CPUCLOCK_VIRT:
226 cpu->cpu = virt_ticks(p);
227 break;
228 case CPUCLOCK_SCHED:
229 cpu->sched = task_sched_runtime(p);
230 break;
231 }
232 return 0;
233}
234
235void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
236{
237 struct signal_struct *sig = tsk->signal;
238 struct task_struct *t;
239
240 times->utime = sig->utime;
241 times->stime = sig->stime;
242 times->sum_exec_runtime = sig->sum_sched_runtime;
243
244 rcu_read_lock();
245 /* make sure we can trust tsk->thread_group list */
246 if (!likely(pid_alive(tsk)))
247 goto out;
248
249 t = tsk;
250 do {
251 times->utime = cputime_add(times->utime, t->utime);
252 times->stime = cputime_add(times->stime, t->stime);
253 times->sum_exec_runtime += task_sched_runtime(t);
254 } while_each_thread(tsk, t);
255out:
256 rcu_read_unlock();
257}
258
259static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
260{
261 if (cputime_gt(b->utime, a->utime))
262 a->utime = b->utime;
263
264 if (cputime_gt(b->stime, a->stime))
265 a->stime = b->stime;
266
267 if (b->sum_exec_runtime > a->sum_exec_runtime)
268 a->sum_exec_runtime = b->sum_exec_runtime;
269}
270
271void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
272{
273 struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
274 struct task_cputime sum;
275 unsigned long flags;
276
277 if (!cputimer->running) {
278 /*
279 * The POSIX timer interface allows for absolute time expiry
280 * values through the TIMER_ABSTIME flag, therefore we have
281 * to synchronize the timer to the clock every time we start
282 * it.
283 */
284 thread_group_cputime(tsk, &sum);
285 spin_lock_irqsave(&cputimer->lock, flags);
286 cputimer->running = 1;
287 update_gt_cputime(&cputimer->cputime, &sum);
288 } else
289 spin_lock_irqsave(&cputimer->lock, flags);
290 *times = cputimer->cputime;
291 spin_unlock_irqrestore(&cputimer->lock, flags);
292}
293
294/*
295 * Sample a process (thread group) clock for the given group_leader task.
296 * Must be called with tasklist_lock held for reading.
297 */
298static int cpu_clock_sample_group(const clockid_t which_clock,
299 struct task_struct *p,
300 union cpu_time_count *cpu)
301{
302 struct task_cputime cputime;
303
304 switch (CPUCLOCK_WHICH(which_clock)) {
305 default:
306 return -EINVAL;
307 case CPUCLOCK_PROF:
308 thread_group_cputime(p, &cputime);
309 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
310 break;
311 case CPUCLOCK_VIRT:
312 thread_group_cputime(p, &cputime);
313 cpu->cpu = cputime.utime;
314 break;
315 case CPUCLOCK_SCHED:
316 thread_group_cputime(p, &cputime);
317 cpu->sched = cputime.sum_exec_runtime;
318 break;
319 }
320 return 0;
321}
322
323
324static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
325{
326 const pid_t pid = CPUCLOCK_PID(which_clock);
327 int error = -EINVAL;
328 union cpu_time_count rtn;
329
330 if (pid == 0) {
331 /*
332 * Special case constant value for our own clocks.
333 * We don't have to do any lookup to find ourselves.
334 */
335 if (CPUCLOCK_PERTHREAD(which_clock)) {
336 /*
337 * Sampling just ourselves we can do with no locking.
338 */
339 error = cpu_clock_sample(which_clock,
340 current, &rtn);
341 } else {
342 read_lock(&tasklist_lock);
343 error = cpu_clock_sample_group(which_clock,
344 current, &rtn);
345 read_unlock(&tasklist_lock);
346 }
347 } else {
348 /*
349 * Find the given PID, and validate that the caller
350 * should be able to see it.
351 */
352 struct task_struct *p;
353 rcu_read_lock();
354 p = find_task_by_vpid(pid);
355 if (p) {
356 if (CPUCLOCK_PERTHREAD(which_clock)) {
357 if (same_thread_group(p, current)) {
358 error = cpu_clock_sample(which_clock,
359 p, &rtn);
360 }
361 } else {
362 read_lock(&tasklist_lock);
363 if (thread_group_leader(p) && p->sighand) {
364 error =
365 cpu_clock_sample_group(which_clock,
366 p, &rtn);
367 }
368 read_unlock(&tasklist_lock);
369 }
370 }
371 rcu_read_unlock();
372 }
373
374 if (error)
375 return error;
376 sample_to_timespec(which_clock, rtn, tp);
377 return 0;
378}
379
380
381/*
382 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
383 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
384 * new timer already all-zeros initialized.
385 */
386static int posix_cpu_timer_create(struct k_itimer *new_timer)
387{
388 int ret = 0;
389 const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
390 struct task_struct *p;
391
392 if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
393 return -EINVAL;
394
395 INIT_LIST_HEAD(&new_timer->it.cpu.entry);
396
397 rcu_read_lock();
398 if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
399 if (pid == 0) {
400 p = current;
401 } else {
402 p = find_task_by_vpid(pid);
403 if (p && !same_thread_group(p, current))
404 p = NULL;
405 }
406 } else {
407 if (pid == 0) {
408 p = current->group_leader;
409 } else {
410 p = find_task_by_vpid(pid);
411 if (p && !has_group_leader_pid(p))
412 p = NULL;
413 }
414 }
415 new_timer->it.cpu.task = p;
416 if (p) {
417 get_task_struct(p);
418 } else {
419 ret = -EINVAL;
420 }
421 rcu_read_unlock();
422
423 return ret;
424}
425
426/*
427 * Clean up a CPU-clock timer that is about to be destroyed.
428 * This is called from timer deletion with the timer already locked.
429 * If we return TIMER_RETRY, it's necessary to release the timer's lock
430 * and try again. (This happens when the timer is in the middle of firing.)
431 */
432static int posix_cpu_timer_del(struct k_itimer *timer)
433{
434 struct task_struct *p = timer->it.cpu.task;
435 int ret = 0;
436
437 if (likely(p != NULL)) {
438 read_lock(&tasklist_lock);
439 if (unlikely(p->sighand == NULL)) {
440 /*
441 * We raced with the reaping of the task.
442 * The deletion should have cleared us off the list.
443 */
444 BUG_ON(!list_empty(&timer->it.cpu.entry));
445 } else {
446 spin_lock(&p->sighand->siglock);
447 if (timer->it.cpu.firing)
448 ret = TIMER_RETRY;
449 else
450 list_del(&timer->it.cpu.entry);
451 spin_unlock(&p->sighand->siglock);
452 }
453 read_unlock(&tasklist_lock);
454
455 if (!ret)
456 put_task_struct(p);
457 }
458
459 return ret;
460}
461
462/*
463 * Clean out CPU timers still ticking when a thread exited. The task
464 * pointer is cleared, and the expiry time is replaced with the residual
465 * time for later timer_gettime calls to return.
466 * This must be called with the siglock held.
467 */
468static void cleanup_timers(struct list_head *head,
469 cputime_t utime, cputime_t stime,
470 unsigned long long sum_exec_runtime)
471{
472 struct cpu_timer_list *timer, *next;
473 cputime_t ptime = cputime_add(utime, stime);
474
475 list_for_each_entry_safe(timer, next, head, entry) {
476 list_del_init(&timer->entry);
477 if (cputime_lt(timer->expires.cpu, ptime)) {
478 timer->expires.cpu = cputime_zero;
479 } else {
480 timer->expires.cpu = cputime_sub(timer->expires.cpu,
481 ptime);
482 }
483 }
484
485 ++head;
486 list_for_each_entry_safe(timer, next, head, entry) {
487 list_del_init(&timer->entry);
488 if (cputime_lt(timer->expires.cpu, utime)) {
489 timer->expires.cpu = cputime_zero;
490 } else {
491 timer->expires.cpu = cputime_sub(timer->expires.cpu,
492 utime);
493 }
494 }
495
496 ++head;
497 list_for_each_entry_safe(timer, next, head, entry) {
498 list_del_init(&timer->entry);
499 if (timer->expires.sched < sum_exec_runtime) {
500 timer->expires.sched = 0;
501 } else {
502 timer->expires.sched -= sum_exec_runtime;
503 }
504 }
505}
506
507/*
508 * These are both called with the siglock held, when the current thread
509 * is being reaped. When the final (leader) thread in the group is reaped,
510 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
511 */
512void posix_cpu_timers_exit(struct task_struct *tsk)
513{
514 cleanup_timers(tsk->cpu_timers,
515 tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
516
517}
518void posix_cpu_timers_exit_group(struct task_struct *tsk)
519{
520 struct signal_struct *const sig = tsk->signal;
521
522 cleanup_timers(tsk->signal->cpu_timers,
523 cputime_add(tsk->utime, sig->utime),
524 cputime_add(tsk->stime, sig->stime),
525 tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
526}
527
528static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
529{
530 /*
531 * That's all for this thread or process.
532 * We leave our residual in expires to be reported.
533 */
534 put_task_struct(timer->it.cpu.task);
535 timer->it.cpu.task = NULL;
536 timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
537 timer->it.cpu.expires,
538 now);
539}
540
541static inline int expires_gt(cputime_t expires, cputime_t new_exp)
542{
543 return cputime_eq(expires, cputime_zero) ||
544 cputime_gt(expires, new_exp);
545}
546
547/*
548 * Insert the timer on the appropriate list before any timers that
549 * expire later. This must be called with the tasklist_lock held
550 * for reading, interrupts disabled and p->sighand->siglock taken.
551 */
552static void arm_timer(struct k_itimer *timer)
553{
554 struct task_struct *p = timer->it.cpu.task;
555 struct list_head *head, *listpos;
556 struct task_cputime *cputime_expires;
557 struct cpu_timer_list *const nt = &timer->it.cpu;
558 struct cpu_timer_list *next;
559
560 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
561 head = p->cpu_timers;
562 cputime_expires = &p->cputime_expires;
563 } else {
564 head = p->signal->cpu_timers;
565 cputime_expires = &p->signal->cputime_expires;
566 }
567 head += CPUCLOCK_WHICH(timer->it_clock);
568
569 listpos = head;
570 list_for_each_entry(next, head, entry) {
571 if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
572 break;
573 listpos = &next->entry;
574 }
575 list_add(&nt->entry, listpos);
576
577 if (listpos == head) {
578 union cpu_time_count *exp = &nt->expires;
579
580 /*
581 * We are the new earliest-expiring POSIX 1.b timer, hence
582 * need to update expiration cache. Take into account that
583 * for process timers we share expiration cache with itimers
584 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
585 */
586
587 switch (CPUCLOCK_WHICH(timer->it_clock)) {
588 case CPUCLOCK_PROF:
589 if (expires_gt(cputime_expires->prof_exp, exp->cpu))
590 cputime_expires->prof_exp = exp->cpu;
591 break;
592 case CPUCLOCK_VIRT:
593 if (expires_gt(cputime_expires->virt_exp, exp->cpu))
594 cputime_expires->virt_exp = exp->cpu;
595 break;
596 case CPUCLOCK_SCHED:
597 if (cputime_expires->sched_exp == 0 ||
598 cputime_expires->sched_exp > exp->sched)
599 cputime_expires->sched_exp = exp->sched;
600 break;
601 }
602 }
603}
604
605/*
606 * The timer is locked, fire it and arrange for its reload.
607 */
608static void cpu_timer_fire(struct k_itimer *timer)
609{
610 if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
611 /*
612 * User don't want any signal.
613 */
614 timer->it.cpu.expires.sched = 0;
615 } else if (unlikely(timer->sigq == NULL)) {
616 /*
617 * This a special case for clock_nanosleep,
618 * not a normal timer from sys_timer_create.
619 */
620 wake_up_process(timer->it_process);
621 timer->it.cpu.expires.sched = 0;
622 } else if (timer->it.cpu.incr.sched == 0) {
623 /*
624 * One-shot timer. Clear it as soon as it's fired.
625 */
626 posix_timer_event(timer, 0);
627 timer->it.cpu.expires.sched = 0;
628 } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
629 /*
630 * The signal did not get queued because the signal
631 * was ignored, so we won't get any callback to
632 * reload the timer. But we need to keep it
633 * ticking in case the signal is deliverable next time.
634 */
635 posix_cpu_timer_schedule(timer);
636 }
637}
638
639/*
640 * Sample a process (thread group) timer for the given group_leader task.
641 * Must be called with tasklist_lock held for reading.
642 */
643static int cpu_timer_sample_group(const clockid_t which_clock,
644 struct task_struct *p,
645 union cpu_time_count *cpu)
646{
647 struct task_cputime cputime;
648
649 thread_group_cputimer(p, &cputime);
650 switch (CPUCLOCK_WHICH(which_clock)) {
651 default:
652 return -EINVAL;
653 case CPUCLOCK_PROF:
654 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
655 break;
656 case CPUCLOCK_VIRT:
657 cpu->cpu = cputime.utime;
658 break;
659 case CPUCLOCK_SCHED:
660 cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
661 break;
662 }
663 return 0;
664}
665
666/*
667 * Guts of sys_timer_settime for CPU timers.
668 * This is called with the timer locked and interrupts disabled.
669 * If we return TIMER_RETRY, it's necessary to release the timer's lock
670 * and try again. (This happens when the timer is in the middle of firing.)
671 */
672static int posix_cpu_timer_set(struct k_itimer *timer, int flags,
673 struct itimerspec *new, struct itimerspec *old)
674{
675 struct task_struct *p = timer->it.cpu.task;
676 union cpu_time_count old_expires, new_expires, old_incr, val;
677 int ret;
678
679 if (unlikely(p == NULL)) {
680 /*
681 * Timer refers to a dead task's clock.
682 */
683 return -ESRCH;
684 }
685
686 new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
687
688 read_lock(&tasklist_lock);
689 /*
690 * We need the tasklist_lock to protect against reaping that
691 * clears p->sighand. If p has just been reaped, we can no
692 * longer get any information about it at all.
693 */
694 if (unlikely(p->sighand == NULL)) {
695 read_unlock(&tasklist_lock);
696 put_task_struct(p);
697 timer->it.cpu.task = NULL;
698 return -ESRCH;
699 }
700
701 /*
702 * Disarm any old timer after extracting its expiry time.
703 */
704 BUG_ON(!irqs_disabled());
705
706 ret = 0;
707 old_incr = timer->it.cpu.incr;
708 spin_lock(&p->sighand->siglock);
709 old_expires = timer->it.cpu.expires;
710 if (unlikely(timer->it.cpu.firing)) {
711 timer->it.cpu.firing = -1;
712 ret = TIMER_RETRY;
713 } else
714 list_del_init(&timer->it.cpu.entry);
715
716 /*
717 * We need to sample the current value to convert the new
718 * value from to relative and absolute, and to convert the
719 * old value from absolute to relative. To set a process
720 * timer, we need a sample to balance the thread expiry
721 * times (in arm_timer). With an absolute time, we must
722 * check if it's already passed. In short, we need a sample.
723 */
724 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
725 cpu_clock_sample(timer->it_clock, p, &val);
726 } else {
727 cpu_timer_sample_group(timer->it_clock, p, &val);
728 }
729
730 if (old) {
731 if (old_expires.sched == 0) {
732 old->it_value.tv_sec = 0;
733 old->it_value.tv_nsec = 0;
734 } else {
735 /*
736 * Update the timer in case it has
737 * overrun already. If it has,
738 * we'll report it as having overrun
739 * and with the next reloaded timer
740 * already ticking, though we are
741 * swallowing that pending
742 * notification here to install the
743 * new setting.
744 */
745 bump_cpu_timer(timer, val);
746 if (cpu_time_before(timer->it_clock, val,
747 timer->it.cpu.expires)) {
748 old_expires = cpu_time_sub(
749 timer->it_clock,
750 timer->it.cpu.expires, val);
751 sample_to_timespec(timer->it_clock,
752 old_expires,
753 &old->it_value);
754 } else {
755 old->it_value.tv_nsec = 1;
756 old->it_value.tv_sec = 0;
757 }
758 }
759 }
760
761 if (unlikely(ret)) {
762 /*
763 * We are colliding with the timer actually firing.
764 * Punt after filling in the timer's old value, and
765 * disable this firing since we are already reporting
766 * it as an overrun (thanks to bump_cpu_timer above).
767 */
768 spin_unlock(&p->sighand->siglock);
769 read_unlock(&tasklist_lock);
770 goto out;
771 }
772
773 if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
774 cpu_time_add(timer->it_clock, &new_expires, val);
775 }
776
777 /*
778 * Install the new expiry time (or zero).
779 * For a timer with no notification action, we don't actually
780 * arm the timer (we'll just fake it for timer_gettime).
781 */
782 timer->it.cpu.expires = new_expires;
783 if (new_expires.sched != 0 &&
784 cpu_time_before(timer->it_clock, val, new_expires)) {
785 arm_timer(timer);
786 }
787
788 spin_unlock(&p->sighand->siglock);
789 read_unlock(&tasklist_lock);
790
791 /*
792 * Install the new reload setting, and
793 * set up the signal and overrun bookkeeping.
794 */
795 timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
796 &new->it_interval);
797
798 /*
799 * This acts as a modification timestamp for the timer,
800 * so any automatic reload attempt will punt on seeing
801 * that we have reset the timer manually.
802 */
803 timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
804 ~REQUEUE_PENDING;
805 timer->it_overrun_last = 0;
806 timer->it_overrun = -1;
807
808 if (new_expires.sched != 0 &&
809 !cpu_time_before(timer->it_clock, val, new_expires)) {
810 /*
811 * The designated time already passed, so we notify
812 * immediately, even if the thread never runs to
813 * accumulate more time on this clock.
814 */
815 cpu_timer_fire(timer);
816 }
817
818 ret = 0;
819 out:
820 if (old) {
821 sample_to_timespec(timer->it_clock,
822 old_incr, &old->it_interval);
823 }
824 return ret;
825}
826
827static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
828{
829 union cpu_time_count now;
830 struct task_struct *p = timer->it.cpu.task;
831 int clear_dead;
832
833 /*
834 * Easy part: convert the reload time.
835 */
836 sample_to_timespec(timer->it_clock,
837 timer->it.cpu.incr, &itp->it_interval);
838
839 if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all. */
840 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
841 return;
842 }
843
844 if (unlikely(p == NULL)) {
845 /*
846 * This task already died and the timer will never fire.
847 * In this case, expires is actually the dead value.
848 */
849 dead:
850 sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
851 &itp->it_value);
852 return;
853 }
854
855 /*
856 * Sample the clock to take the difference with the expiry time.
857 */
858 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
859 cpu_clock_sample(timer->it_clock, p, &now);
860 clear_dead = p->exit_state;
861 } else {
862 read_lock(&tasklist_lock);
863 if (unlikely(p->sighand == NULL)) {
864 /*
865 * The process has been reaped.
866 * We can't even collect a sample any more.
867 * Call the timer disarmed, nothing else to do.
868 */
869 put_task_struct(p);
870 timer->it.cpu.task = NULL;
871 timer->it.cpu.expires.sched = 0;
872 read_unlock(&tasklist_lock);
873 goto dead;
874 } else {
875 cpu_timer_sample_group(timer->it_clock, p, &now);
876 clear_dead = (unlikely(p->exit_state) &&
877 thread_group_empty(p));
878 }
879 read_unlock(&tasklist_lock);
880 }
881
882 if (unlikely(clear_dead)) {
883 /*
884 * We've noticed that the thread is dead, but
885 * not yet reaped. Take this opportunity to
886 * drop our task ref.
887 */
888 clear_dead_task(timer, now);
889 goto dead;
890 }
891
892 if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
893 sample_to_timespec(timer->it_clock,
894 cpu_time_sub(timer->it_clock,
895 timer->it.cpu.expires, now),
896 &itp->it_value);
897 } else {
898 /*
899 * The timer should have expired already, but the firing
900 * hasn't taken place yet. Say it's just about to expire.
901 */
902 itp->it_value.tv_nsec = 1;
903 itp->it_value.tv_sec = 0;
904 }
905}
906
907/*
908 * Check for any per-thread CPU timers that have fired and move them off
909 * the tsk->cpu_timers[N] list onto the firing list. Here we update the
910 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
911 */
912static void check_thread_timers(struct task_struct *tsk,
913 struct list_head *firing)
914{
915 int maxfire;
916 struct list_head *timers = tsk->cpu_timers;
917 struct signal_struct *const sig = tsk->signal;
918 unsigned long soft;
919
920 maxfire = 20;
921 tsk->cputime_expires.prof_exp = cputime_zero;
922 while (!list_empty(timers)) {
923 struct cpu_timer_list *t = list_first_entry(timers,
924 struct cpu_timer_list,
925 entry);
926 if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
927 tsk->cputime_expires.prof_exp = t->expires.cpu;
928 break;
929 }
930 t->firing = 1;
931 list_move_tail(&t->entry, firing);
932 }
933
934 ++timers;
935 maxfire = 20;
936 tsk->cputime_expires.virt_exp = cputime_zero;
937 while (!list_empty(timers)) {
938 struct cpu_timer_list *t = list_first_entry(timers,
939 struct cpu_timer_list,
940 entry);
941 if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
942 tsk->cputime_expires.virt_exp = t->expires.cpu;
943 break;
944 }
945 t->firing = 1;
946 list_move_tail(&t->entry, firing);
947 }
948
949 ++timers;
950 maxfire = 20;
951 tsk->cputime_expires.sched_exp = 0;
952 while (!list_empty(timers)) {
953 struct cpu_timer_list *t = list_first_entry(timers,
954 struct cpu_timer_list,
955 entry);
956 if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
957 tsk->cputime_expires.sched_exp = t->expires.sched;
958 break;
959 }
960 t->firing = 1;
961 list_move_tail(&t->entry, firing);
962 }
963
964 /*
965 * Check for the special case thread timers.
966 */
967 soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
968 if (soft != RLIM_INFINITY) {
969 unsigned long hard =
970 ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
971
972 if (hard != RLIM_INFINITY &&
973 tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
974 /*
975 * At the hard limit, we just die.
976 * No need to calculate anything else now.
977 */
978 __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
979 return;
980 }
981 if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
982 /*
983 * At the soft limit, send a SIGXCPU every second.
984 */
985 if (soft < hard) {
986 soft += USEC_PER_SEC;
987 sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
988 }
989 printk(KERN_INFO
990 "RT Watchdog Timeout: %s[%d]\n",
991 tsk->comm, task_pid_nr(tsk));
992 __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
993 }
994 }
995}
996
997static void stop_process_timers(struct signal_struct *sig)
998{
999 struct thread_group_cputimer *cputimer = &sig->cputimer;
1000 unsigned long flags;
1001
1002 spin_lock_irqsave(&cputimer->lock, flags);
1003 cputimer->running = 0;
1004 spin_unlock_irqrestore(&cputimer->lock, flags);
1005}
1006
1007static u32 onecputick;
1008
1009static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
1010 cputime_t *expires, cputime_t cur_time, int signo)
1011{
1012 if (cputime_eq(it->expires, cputime_zero))
1013 return;
1014
1015 if (cputime_ge(cur_time, it->expires)) {
1016 if (!cputime_eq(it->incr, cputime_zero)) {
1017 it->expires = cputime_add(it->expires, it->incr);
1018 it->error += it->incr_error;
1019 if (it->error >= onecputick) {
1020 it->expires = cputime_sub(it->expires,
1021 cputime_one_jiffy);
1022 it->error -= onecputick;
1023 }
1024 } else {
1025 it->expires = cputime_zero;
1026 }
1027
1028 trace_itimer_expire(signo == SIGPROF ?
1029 ITIMER_PROF : ITIMER_VIRTUAL,
1030 tsk->signal->leader_pid, cur_time);
1031 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
1032 }
1033
1034 if (!cputime_eq(it->expires, cputime_zero) &&
1035 (cputime_eq(*expires, cputime_zero) ||
1036 cputime_lt(it->expires, *expires))) {
1037 *expires = it->expires;
1038 }
1039}
1040
1041/**
1042 * task_cputime_zero - Check a task_cputime struct for all zero fields.
1043 *
1044 * @cputime: The struct to compare.
1045 *
1046 * Checks @cputime to see if all fields are zero. Returns true if all fields
1047 * are zero, false if any field is nonzero.
1048 */
1049static inline int task_cputime_zero(const struct task_cputime *cputime)
1050{
1051 if (cputime_eq(cputime->utime, cputime_zero) &&
1052 cputime_eq(cputime->stime, cputime_zero) &&
1053 cputime->sum_exec_runtime == 0)
1054 return 1;
1055 return 0;
1056}
1057
1058/*
1059 * Check for any per-thread CPU timers that have fired and move them
1060 * off the tsk->*_timers list onto the firing list. Per-thread timers
1061 * have already been taken off.
1062 */
1063static void check_process_timers(struct task_struct *tsk,
1064 struct list_head *firing)
1065{
1066 int maxfire;
1067 struct signal_struct *const sig = tsk->signal;
1068 cputime_t utime, ptime, virt_expires, prof_expires;
1069 unsigned long long sum_sched_runtime, sched_expires;
1070 struct list_head *timers = sig->cpu_timers;
1071 struct task_cputime cputime;
1072 unsigned long soft;
1073
1074 /*
1075 * Collect the current process totals.
1076 */
1077 thread_group_cputimer(tsk, &cputime);
1078 utime = cputime.utime;
1079 ptime = cputime_add(utime, cputime.stime);
1080 sum_sched_runtime = cputime.sum_exec_runtime;
1081 maxfire = 20;
1082 prof_expires = cputime_zero;
1083 while (!list_empty(timers)) {
1084 struct cpu_timer_list *tl = list_first_entry(timers,
1085 struct cpu_timer_list,
1086 entry);
1087 if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) {
1088 prof_expires = tl->expires.cpu;
1089 break;
1090 }
1091 tl->firing = 1;
1092 list_move_tail(&tl->entry, firing);
1093 }
1094
1095 ++timers;
1096 maxfire = 20;
1097 virt_expires = cputime_zero;
1098 while (!list_empty(timers)) {
1099 struct cpu_timer_list *tl = list_first_entry(timers,
1100 struct cpu_timer_list,
1101 entry);
1102 if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) {
1103 virt_expires = tl->expires.cpu;
1104 break;
1105 }
1106 tl->firing = 1;
1107 list_move_tail(&tl->entry, firing);
1108 }
1109
1110 ++timers;
1111 maxfire = 20;
1112 sched_expires = 0;
1113 while (!list_empty(timers)) {
1114 struct cpu_timer_list *tl = list_first_entry(timers,
1115 struct cpu_timer_list,
1116 entry);
1117 if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1118 sched_expires = tl->expires.sched;
1119 break;
1120 }
1121 tl->firing = 1;
1122 list_move_tail(&tl->entry, firing);
1123 }
1124
1125 /*
1126 * Check for the special case process timers.
1127 */
1128 check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1129 SIGPROF);
1130 check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1131 SIGVTALRM);
1132 soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1133 if (soft != RLIM_INFINITY) {
1134 unsigned long psecs = cputime_to_secs(ptime);
1135 unsigned long hard =
1136 ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
1137 cputime_t x;
1138 if (psecs >= hard) {
1139 /*
1140 * At the hard limit, we just die.
1141 * No need to calculate anything else now.
1142 */
1143 __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1144 return;
1145 }
1146 if (psecs >= soft) {
1147 /*
1148 * At the soft limit, send a SIGXCPU every second.
1149 */
1150 __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1151 if (soft < hard) {
1152 soft++;
1153 sig->rlim[RLIMIT_CPU].rlim_cur = soft;
1154 }
1155 }
1156 x = secs_to_cputime(soft);
1157 if (cputime_eq(prof_expires, cputime_zero) ||
1158 cputime_lt(x, prof_expires)) {
1159 prof_expires = x;
1160 }
1161 }
1162
1163 sig->cputime_expires.prof_exp = prof_expires;
1164 sig->cputime_expires.virt_exp = virt_expires;
1165 sig->cputime_expires.sched_exp = sched_expires;
1166 if (task_cputime_zero(&sig->cputime_expires))
1167 stop_process_timers(sig);
1168}
1169
1170/*
1171 * This is called from the signal code (via do_schedule_next_timer)
1172 * when the last timer signal was delivered and we have to reload the timer.
1173 */
1174void posix_cpu_timer_schedule(struct k_itimer *timer)
1175{
1176 struct task_struct *p = timer->it.cpu.task;
1177 union cpu_time_count now;
1178
1179 if (unlikely(p == NULL))
1180 /*
1181 * The task was cleaned up already, no future firings.
1182 */
1183 goto out;
1184
1185 /*
1186 * Fetch the current sample and update the timer's expiry time.
1187 */
1188 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1189 cpu_clock_sample(timer->it_clock, p, &now);
1190 bump_cpu_timer(timer, now);
1191 if (unlikely(p->exit_state)) {
1192 clear_dead_task(timer, now);
1193 goto out;
1194 }
1195 read_lock(&tasklist_lock); /* arm_timer needs it. */
1196 spin_lock(&p->sighand->siglock);
1197 } else {
1198 read_lock(&tasklist_lock);
1199 if (unlikely(p->sighand == NULL)) {
1200 /*
1201 * The process has been reaped.
1202 * We can't even collect a sample any more.
1203 */
1204 put_task_struct(p);
1205 timer->it.cpu.task = p = NULL;
1206 timer->it.cpu.expires.sched = 0;
1207 goto out_unlock;
1208 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1209 /*
1210 * We've noticed that the thread is dead, but
1211 * not yet reaped. Take this opportunity to
1212 * drop our task ref.
1213 */
1214 clear_dead_task(timer, now);
1215 goto out_unlock;
1216 }
1217 spin_lock(&p->sighand->siglock);
1218 cpu_timer_sample_group(timer->it_clock, p, &now);
1219 bump_cpu_timer(timer, now);
1220 /* Leave the tasklist_lock locked for the call below. */
1221 }
1222
1223 /*
1224 * Now re-arm for the new expiry time.
1225 */
1226 BUG_ON(!irqs_disabled());
1227 arm_timer(timer);
1228 spin_unlock(&p->sighand->siglock);
1229
1230out_unlock:
1231 read_unlock(&tasklist_lock);
1232
1233out:
1234 timer->it_overrun_last = timer->it_overrun;
1235 timer->it_overrun = -1;
1236 ++timer->it_requeue_pending;
1237}
1238
1239/**
1240 * task_cputime_expired - Compare two task_cputime entities.
1241 *
1242 * @sample: The task_cputime structure to be checked for expiration.
1243 * @expires: Expiration times, against which @sample will be checked.
1244 *
1245 * Checks @sample against @expires to see if any field of @sample has expired.
1246 * Returns true if any field of the former is greater than the corresponding
1247 * field of the latter if the latter field is set. Otherwise returns false.
1248 */
1249static inline int task_cputime_expired(const struct task_cputime *sample,
1250 const struct task_cputime *expires)
1251{
1252 if (!cputime_eq(expires->utime, cputime_zero) &&
1253 cputime_ge(sample->utime, expires->utime))
1254 return 1;
1255 if (!cputime_eq(expires->stime, cputime_zero) &&
1256 cputime_ge(cputime_add(sample->utime, sample->stime),
1257 expires->stime))
1258 return 1;
1259 if (expires->sum_exec_runtime != 0 &&
1260 sample->sum_exec_runtime >= expires->sum_exec_runtime)
1261 return 1;
1262 return 0;
1263}
1264
1265/**
1266 * fastpath_timer_check - POSIX CPU timers fast path.
1267 *
1268 * @tsk: The task (thread) being checked.
1269 *
1270 * Check the task and thread group timers. If both are zero (there are no
1271 * timers set) return false. Otherwise snapshot the task and thread group
1272 * timers and compare them with the corresponding expiration times. Return
1273 * true if a timer has expired, else return false.
1274 */
1275static inline int fastpath_timer_check(struct task_struct *tsk)
1276{
1277 struct signal_struct *sig;
1278
1279 if (!task_cputime_zero(&tsk->cputime_expires)) {
1280 struct task_cputime task_sample = {
1281 .utime = tsk->utime,
1282 .stime = tsk->stime,
1283 .sum_exec_runtime = tsk->se.sum_exec_runtime
1284 };
1285
1286 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1287 return 1;
1288 }
1289
1290 sig = tsk->signal;
1291 if (sig->cputimer.running) {
1292 struct task_cputime group_sample;
1293
1294 spin_lock(&sig->cputimer.lock);
1295 group_sample = sig->cputimer.cputime;
1296 spin_unlock(&sig->cputimer.lock);
1297
1298 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1299 return 1;
1300 }
1301
1302 return 0;
1303}
1304
1305/*
1306 * This is called from the timer interrupt handler. The irq handler has
1307 * already updated our counts. We need to check if any timers fire now.
1308 * Interrupts are disabled.
1309 */
1310void run_posix_cpu_timers(struct task_struct *tsk)
1311{
1312 LIST_HEAD(firing);
1313 struct k_itimer *timer, *next;
1314 unsigned long flags;
1315
1316 BUG_ON(!irqs_disabled());
1317
1318 /*
1319 * The fast path checks that there are no expired thread or thread
1320 * group timers. If that's so, just return.
1321 */
1322 if (!fastpath_timer_check(tsk))
1323 return;
1324
1325 if (!lock_task_sighand(tsk, &flags))
1326 return;
1327 /*
1328 * Here we take off tsk->signal->cpu_timers[N] and
1329 * tsk->cpu_timers[N] all the timers that are firing, and
1330 * put them on the firing list.
1331 */
1332 check_thread_timers(tsk, &firing);
1333 /*
1334 * If there are any active process wide timers (POSIX 1.b, itimers,
1335 * RLIMIT_CPU) cputimer must be running.
1336 */
1337 if (tsk->signal->cputimer.running)
1338 check_process_timers(tsk, &firing);
1339
1340 /*
1341 * We must release these locks before taking any timer's lock.
1342 * There is a potential race with timer deletion here, as the
1343 * siglock now protects our private firing list. We have set
1344 * the firing flag in each timer, so that a deletion attempt
1345 * that gets the timer lock before we do will give it up and
1346 * spin until we've taken care of that timer below.
1347 */
1348 unlock_task_sighand(tsk, &flags);
1349
1350 /*
1351 * Now that all the timers on our list have the firing flag,
1352 * no one will touch their list entries but us. We'll take
1353 * each timer's lock before clearing its firing flag, so no
1354 * timer call will interfere.
1355 */
1356 list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1357 int cpu_firing;
1358
1359 spin_lock(&timer->it_lock);
1360 list_del_init(&timer->it.cpu.entry);
1361 cpu_firing = timer->it.cpu.firing;
1362 timer->it.cpu.firing = 0;
1363 /*
1364 * The firing flag is -1 if we collided with a reset
1365 * of the timer, which already reported this
1366 * almost-firing as an overrun. So don't generate an event.
1367 */
1368 if (likely(cpu_firing >= 0))
1369 cpu_timer_fire(timer);
1370 spin_unlock(&timer->it_lock);
1371 }
1372}
1373
1374/*
1375 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1376 * The tsk->sighand->siglock must be held by the caller.
1377 */
1378void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1379 cputime_t *newval, cputime_t *oldval)
1380{
1381 union cpu_time_count now;
1382
1383 BUG_ON(clock_idx == CPUCLOCK_SCHED);
1384 cpu_timer_sample_group(clock_idx, tsk, &now);
1385
1386 if (oldval) {
1387 /*
1388 * We are setting itimer. The *oldval is absolute and we update
1389 * it to be relative, *newval argument is relative and we update
1390 * it to be absolute.
1391 */
1392 if (!cputime_eq(*oldval, cputime_zero)) {
1393 if (cputime_le(*oldval, now.cpu)) {
1394 /* Just about to fire. */
1395 *oldval = cputime_one_jiffy;
1396 } else {
1397 *oldval = cputime_sub(*oldval, now.cpu);
1398 }
1399 }
1400
1401 if (cputime_eq(*newval, cputime_zero))
1402 return;
1403 *newval = cputime_add(*newval, now.cpu);
1404 }
1405
1406 /*
1407 * Update expiration cache if we are the earliest timer, or eventually
1408 * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1409 */
1410 switch (clock_idx) {
1411 case CPUCLOCK_PROF:
1412 if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1413 tsk->signal->cputime_expires.prof_exp = *newval;
1414 break;
1415 case CPUCLOCK_VIRT:
1416 if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1417 tsk->signal->cputime_expires.virt_exp = *newval;
1418 break;
1419 }
1420}
1421
1422static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1423 struct timespec *rqtp, struct itimerspec *it)
1424{
1425 struct k_itimer timer;
1426 int error;
1427
1428 /*
1429 * Set up a temporary timer and then wait for it to go off.
1430 */
1431 memset(&timer, 0, sizeof timer);
1432 spin_lock_init(&timer.it_lock);
1433 timer.it_clock = which_clock;
1434 timer.it_overrun = -1;
1435 error = posix_cpu_timer_create(&timer);
1436 timer.it_process = current;
1437 if (!error) {
1438 static struct itimerspec zero_it;
1439
1440 memset(it, 0, sizeof *it);
1441 it->it_value = *rqtp;
1442
1443 spin_lock_irq(&timer.it_lock);
1444 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1445 if (error) {
1446 spin_unlock_irq(&timer.it_lock);
1447 return error;
1448 }
1449
1450 while (!signal_pending(current)) {
1451 if (timer.it.cpu.expires.sched == 0) {
1452 /*
1453 * Our timer fired and was reset.
1454 */
1455 spin_unlock_irq(&timer.it_lock);
1456 return 0;
1457 }
1458
1459 /*
1460 * Block until cpu_timer_fire (or a signal) wakes us.
1461 */
1462 __set_current_state(TASK_INTERRUPTIBLE);
1463 spin_unlock_irq(&timer.it_lock);
1464 schedule();
1465 spin_lock_irq(&timer.it_lock);
1466 }
1467
1468 /*
1469 * We were interrupted by a signal.
1470 */
1471 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1472 posix_cpu_timer_set(&timer, 0, &zero_it, it);
1473 spin_unlock_irq(&timer.it_lock);
1474
1475 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1476 /*
1477 * It actually did fire already.
1478 */
1479 return 0;
1480 }
1481
1482 error = -ERESTART_RESTARTBLOCK;
1483 }
1484
1485 return error;
1486}
1487
1488static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1489
1490static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1491 struct timespec *rqtp, struct timespec __user *rmtp)
1492{
1493 struct restart_block *restart_block =
1494 ¤t_thread_info()->restart_block;
1495 struct itimerspec it;
1496 int error;
1497
1498 /*
1499 * Diagnose required errors first.
1500 */
1501 if (CPUCLOCK_PERTHREAD(which_clock) &&
1502 (CPUCLOCK_PID(which_clock) == 0 ||
1503 CPUCLOCK_PID(which_clock) == current->pid))
1504 return -EINVAL;
1505
1506 error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1507
1508 if (error == -ERESTART_RESTARTBLOCK) {
1509
1510 if (flags & TIMER_ABSTIME)
1511 return -ERESTARTNOHAND;
1512 /*
1513 * Report back to the user the time still remaining.
1514 */
1515 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1516 return -EFAULT;
1517
1518 restart_block->fn = posix_cpu_nsleep_restart;
1519 restart_block->nanosleep.clockid = which_clock;
1520 restart_block->nanosleep.rmtp = rmtp;
1521 restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1522 }
1523 return error;
1524}
1525
1526static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1527{
1528 clockid_t which_clock = restart_block->nanosleep.clockid;
1529 struct timespec t;
1530 struct itimerspec it;
1531 int error;
1532
1533 t = ns_to_timespec(restart_block->nanosleep.expires);
1534
1535 error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1536
1537 if (error == -ERESTART_RESTARTBLOCK) {
1538 struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1539 /*
1540 * Report back to the user the time still remaining.
1541 */
1542 if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1543 return -EFAULT;
1544
1545 restart_block->nanosleep.expires = timespec_to_ns(&t);
1546 }
1547 return error;
1548
1549}
1550
1551#define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1552#define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1553
1554static int process_cpu_clock_getres(const clockid_t which_clock,
1555 struct timespec *tp)
1556{
1557 return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1558}
1559static int process_cpu_clock_get(const clockid_t which_clock,
1560 struct timespec *tp)
1561{
1562 return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1563}
1564static int process_cpu_timer_create(struct k_itimer *timer)
1565{
1566 timer->it_clock = PROCESS_CLOCK;
1567 return posix_cpu_timer_create(timer);
1568}
1569static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1570 struct timespec *rqtp,
1571 struct timespec __user *rmtp)
1572{
1573 return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1574}
1575static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1576{
1577 return -EINVAL;
1578}
1579static int thread_cpu_clock_getres(const clockid_t which_clock,
1580 struct timespec *tp)
1581{
1582 return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1583}
1584static int thread_cpu_clock_get(const clockid_t which_clock,
1585 struct timespec *tp)
1586{
1587 return posix_cpu_clock_get(THREAD_CLOCK, tp);
1588}
1589static int thread_cpu_timer_create(struct k_itimer *timer)
1590{
1591 timer->it_clock = THREAD_CLOCK;
1592 return posix_cpu_timer_create(timer);
1593}
1594
1595struct k_clock clock_posix_cpu = {
1596 .clock_getres = posix_cpu_clock_getres,
1597 .clock_set = posix_cpu_clock_set,
1598 .clock_get = posix_cpu_clock_get,
1599 .timer_create = posix_cpu_timer_create,
1600 .nsleep = posix_cpu_nsleep,
1601 .nsleep_restart = posix_cpu_nsleep_restart,
1602 .timer_set = posix_cpu_timer_set,
1603 .timer_del = posix_cpu_timer_del,
1604 .timer_get = posix_cpu_timer_get,
1605};
1606
1607static __init int init_posix_cpu_timers(void)
1608{
1609 struct k_clock process = {
1610 .clock_getres = process_cpu_clock_getres,
1611 .clock_get = process_cpu_clock_get,
1612 .timer_create = process_cpu_timer_create,
1613 .nsleep = process_cpu_nsleep,
1614 .nsleep_restart = process_cpu_nsleep_restart,
1615 };
1616 struct k_clock thread = {
1617 .clock_getres = thread_cpu_clock_getres,
1618 .clock_get = thread_cpu_clock_get,
1619 .timer_create = thread_cpu_timer_create,
1620 };
1621 struct timespec ts;
1622
1623 posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1624 posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1625
1626 cputime_to_timespec(cputime_one_jiffy, &ts);
1627 onecputick = ts.tv_nsec;
1628 WARN_ON(ts.tv_sec != 0);
1629
1630 return 0;
1631}
1632__initcall(init_posix_cpu_timers);