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Linux/kernel/time/posix-timers.c

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  1 // SPDX-License-Identifier: GPL-2.0+
  2 /*
  3  * 2002-10-15  Posix Clocks & timers
  4  *                           by George Anzinger george@mvista.com
  5  *                           Copyright (C) 2002 2003 by MontaVista Software.
  6  *
  7  * 2004-06-01  Fix CLOCK_REALTIME clock/timer TIMER_ABSTIME bug.
  8  *                           Copyright (C) 2004 Boris Hu
  9  *
 10  * These are all the functions necessary to implement POSIX clocks & timers
 11  */
 12 #include <linux/mm.h>
 13 #include <linux/interrupt.h>
 14 #include <linux/slab.h>
 15 #include <linux/time.h>
 16 #include <linux/mutex.h>
 17 #include <linux/sched/task.h>
 18 
 19 #include <linux/uaccess.h>
 20 #include <linux/list.h>
 21 #include <linux/init.h>
 22 #include <linux/compiler.h>
 23 #include <linux/hash.h>
 24 #include <linux/posix-clock.h>
 25 #include <linux/posix-timers.h>
 26 #include <linux/syscalls.h>
 27 #include <linux/wait.h>
 28 #include <linux/workqueue.h>
 29 #include <linux/export.h>
 30 #include <linux/hashtable.h>
 31 #include <linux/compat.h>
 32 #include <linux/nospec.h>
 33 
 34 #include "timekeeping.h"
 35 #include "posix-timers.h"
 36 
 37 /*
 38  * Management arrays for POSIX timers. Timers are now kept in static hash table
 39  * with 512 entries.
 40  * Timer ids are allocated by local routine, which selects proper hash head by
 41  * key, constructed from current->signal address and per signal struct counter.
 42  * This keeps timer ids unique per process, but now they can intersect between
 43  * processes.
 44  */
 45 
 46 /*
 47  * Lets keep our timers in a slab cache :-)
 48  */
 49 static struct kmem_cache *posix_timers_cache;
 50 
 51 static DEFINE_HASHTABLE(posix_timers_hashtable, 9);
 52 static DEFINE_SPINLOCK(hash_lock);
 53 
 54 static const struct k_clock * const posix_clocks[];
 55 static const struct k_clock *clockid_to_kclock(const clockid_t id);
 56 static const struct k_clock clock_realtime, clock_monotonic;
 57 
 58 /*
 59  * we assume that the new SIGEV_THREAD_ID shares no bits with the other
 60  * SIGEV values.  Here we put out an error if this assumption fails.
 61  */
 62 #if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
 63                        ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
 64 #error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
 65 #endif
 66 
 67 /*
 68  * The timer ID is turned into a timer address by idr_find().
 69  * Verifying a valid ID consists of:
 70  *
 71  * a) checking that idr_find() returns other than -1.
 72  * b) checking that the timer id matches the one in the timer itself.
 73  * c) that the timer owner is in the callers thread group.
 74  */
 75 
 76 /*
 77  * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
 78  *          to implement others.  This structure defines the various
 79  *          clocks.
 80  *
 81  * RESOLUTION: Clock resolution is used to round up timer and interval
 82  *          times, NOT to report clock times, which are reported with as
 83  *          much resolution as the system can muster.  In some cases this
 84  *          resolution may depend on the underlying clock hardware and
 85  *          may not be quantifiable until run time, and only then is the
 86  *          necessary code is written.  The standard says we should say
 87  *          something about this issue in the documentation...
 88  *
 89  * FUNCTIONS: The CLOCKs structure defines possible functions to
 90  *          handle various clock functions.
 91  *
 92  *          The standard POSIX timer management code assumes the
 93  *          following: 1.) The k_itimer struct (sched.h) is used for
 94  *          the timer.  2.) The list, it_lock, it_clock, it_id and
 95  *          it_pid fields are not modified by timer code.
 96  *
 97  * Permissions: It is assumed that the clock_settime() function defined
 98  *          for each clock will take care of permission checks.  Some
 99  *          clocks may be set able by any user (i.e. local process
100  *          clocks) others not.  Currently the only set able clock we
101  *          have is CLOCK_REALTIME and its high res counter part, both of
102  *          which we beg off on and pass to do_sys_settimeofday().
103  */
104 static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
105 
106 #define lock_timer(tid, flags)                                             \
107 ({      struct k_itimer *__timr;                                           \
108         __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags));  \
109         __timr;                                                            \
110 })
111 
112 static int hash(struct signal_struct *sig, unsigned int nr)
113 {
114         return hash_32(hash32_ptr(sig) ^ nr, HASH_BITS(posix_timers_hashtable));
115 }
116 
117 static struct k_itimer *__posix_timers_find(struct hlist_head *head,
118                                             struct signal_struct *sig,
119                                             timer_t id)
120 {
121         struct k_itimer *timer;
122 
123         hlist_for_each_entry_rcu(timer, head, t_hash) {
124                 if ((timer->it_signal == sig) && (timer->it_id == id))
125                         return timer;
126         }
127         return NULL;
128 }
129 
130 static struct k_itimer *posix_timer_by_id(timer_t id)
131 {
132         struct signal_struct *sig = current->signal;
133         struct hlist_head *head = &posix_timers_hashtable[hash(sig, id)];
134 
135         return __posix_timers_find(head, sig, id);
136 }
137 
138 static int posix_timer_add(struct k_itimer *timer)
139 {
140         struct signal_struct *sig = current->signal;
141         int first_free_id = sig->posix_timer_id;
142         struct hlist_head *head;
143         int ret = -ENOENT;
144 
145         do {
146                 spin_lock(&hash_lock);
147                 head = &posix_timers_hashtable[hash(sig, sig->posix_timer_id)];
148                 if (!__posix_timers_find(head, sig, sig->posix_timer_id)) {
149                         hlist_add_head_rcu(&timer->t_hash, head);
150                         ret = sig->posix_timer_id;
151                 }
152                 if (++sig->posix_timer_id < 0)
153                         sig->posix_timer_id = 0;
154                 if ((sig->posix_timer_id == first_free_id) && (ret == -ENOENT))
155                         /* Loop over all possible ids completed */
156                         ret = -EAGAIN;
157                 spin_unlock(&hash_lock);
158         } while (ret == -ENOENT);
159         return ret;
160 }
161 
162 static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
163 {
164         spin_unlock_irqrestore(&timr->it_lock, flags);
165 }
166 
167 /* Get clock_realtime */
168 static int posix_clock_realtime_get(clockid_t which_clock, struct timespec64 *tp)
169 {
170         ktime_get_real_ts64(tp);
171         return 0;
172 }
173 
174 /* Set clock_realtime */
175 static int posix_clock_realtime_set(const clockid_t which_clock,
176                                     const struct timespec64 *tp)
177 {
178         return do_sys_settimeofday64(tp, NULL);
179 }
180 
181 static int posix_clock_realtime_adj(const clockid_t which_clock,
182                                     struct __kernel_timex *t)
183 {
184         return do_adjtimex(t);
185 }
186 
187 /*
188  * Get monotonic time for posix timers
189  */
190 static int posix_ktime_get_ts(clockid_t which_clock, struct timespec64 *tp)
191 {
192         ktime_get_ts64(tp);
193         return 0;
194 }
195 
196 /*
197  * Get monotonic-raw time for posix timers
198  */
199 static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec64 *tp)
200 {
201         ktime_get_raw_ts64(tp);
202         return 0;
203 }
204 
205 
206 static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec64 *tp)
207 {
208         ktime_get_coarse_real_ts64(tp);
209         return 0;
210 }
211 
212 static int posix_get_monotonic_coarse(clockid_t which_clock,
213                                                 struct timespec64 *tp)
214 {
215         ktime_get_coarse_ts64(tp);
216         return 0;
217 }
218 
219 static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *tp)
220 {
221         *tp = ktime_to_timespec64(KTIME_LOW_RES);
222         return 0;
223 }
224 
225 static int posix_get_boottime(const clockid_t which_clock, struct timespec64 *tp)
226 {
227         ktime_get_boottime_ts64(tp);
228         return 0;
229 }
230 
231 static int posix_get_tai(clockid_t which_clock, struct timespec64 *tp)
232 {
233         ktime_get_clocktai_ts64(tp);
234         return 0;
235 }
236 
237 static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
238 {
239         tp->tv_sec = 0;
240         tp->tv_nsec = hrtimer_resolution;
241         return 0;
242 }
243 
244 /*
245  * Initialize everything, well, just everything in Posix clocks/timers ;)
246  */
247 static __init int init_posix_timers(void)
248 {
249         posix_timers_cache = kmem_cache_create("posix_timers_cache",
250                                         sizeof (struct k_itimer), 0, SLAB_PANIC,
251                                         NULL);
252         return 0;
253 }
254 __initcall(init_posix_timers);
255 
256 /*
257  * The siginfo si_overrun field and the return value of timer_getoverrun(2)
258  * are of type int. Clamp the overrun value to INT_MAX
259  */
260 static inline int timer_overrun_to_int(struct k_itimer *timr, int baseval)
261 {
262         s64 sum = timr->it_overrun_last + (s64)baseval;
263 
264         return sum > (s64)INT_MAX ? INT_MAX : (int)sum;
265 }
266 
267 static void common_hrtimer_rearm(struct k_itimer *timr)
268 {
269         struct hrtimer *timer = &timr->it.real.timer;
270 
271         timr->it_overrun += hrtimer_forward(timer, timer->base->get_time(),
272                                             timr->it_interval);
273         hrtimer_restart(timer);
274 }
275 
276 /*
277  * This function is exported for use by the signal deliver code.  It is
278  * called just prior to the info block being released and passes that
279  * block to us.  It's function is to update the overrun entry AND to
280  * restart the timer.  It should only be called if the timer is to be
281  * restarted (i.e. we have flagged this in the sys_private entry of the
282  * info block).
283  *
284  * To protect against the timer going away while the interrupt is queued,
285  * we require that the it_requeue_pending flag be set.
286  */
287 void posixtimer_rearm(struct kernel_siginfo *info)
288 {
289         struct k_itimer *timr;
290         unsigned long flags;
291 
292         timr = lock_timer(info->si_tid, &flags);
293         if (!timr)
294                 return;
295 
296         if (timr->it_interval && timr->it_requeue_pending == info->si_sys_private) {
297                 timr->kclock->timer_rearm(timr);
298 
299                 timr->it_active = 1;
300                 timr->it_overrun_last = timr->it_overrun;
301                 timr->it_overrun = -1LL;
302                 ++timr->it_requeue_pending;
303 
304                 info->si_overrun = timer_overrun_to_int(timr, info->si_overrun);
305         }
306 
307         unlock_timer(timr, flags);
308 }
309 
310 int posix_timer_event(struct k_itimer *timr, int si_private)
311 {
312         enum pid_type type;
313         int ret = -1;
314         /*
315          * FIXME: if ->sigq is queued we can race with
316          * dequeue_signal()->posixtimer_rearm().
317          *
318          * If dequeue_signal() sees the "right" value of
319          * si_sys_private it calls posixtimer_rearm().
320          * We re-queue ->sigq and drop ->it_lock().
321          * posixtimer_rearm() locks the timer
322          * and re-schedules it while ->sigq is pending.
323          * Not really bad, but not that we want.
324          */
325         timr->sigq->info.si_sys_private = si_private;
326 
327         type = !(timr->it_sigev_notify & SIGEV_THREAD_ID) ? PIDTYPE_TGID : PIDTYPE_PID;
328         ret = send_sigqueue(timr->sigq, timr->it_pid, type);
329         /* If we failed to send the signal the timer stops. */
330         return ret > 0;
331 }
332 
333 /*
334  * This function gets called when a POSIX.1b interval timer expires.  It
335  * is used as a callback from the kernel internal timer.  The
336  * run_timer_list code ALWAYS calls with interrupts on.
337 
338  * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
339  */
340 static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
341 {
342         struct k_itimer *timr;
343         unsigned long flags;
344         int si_private = 0;
345         enum hrtimer_restart ret = HRTIMER_NORESTART;
346 
347         timr = container_of(timer, struct k_itimer, it.real.timer);
348         spin_lock_irqsave(&timr->it_lock, flags);
349 
350         timr->it_active = 0;
351         if (timr->it_interval != 0)
352                 si_private = ++timr->it_requeue_pending;
353 
354         if (posix_timer_event(timr, si_private)) {
355                 /*
356                  * signal was not sent because of sig_ignor
357                  * we will not get a call back to restart it AND
358                  * it should be restarted.
359                  */
360                 if (timr->it_interval != 0) {
361                         ktime_t now = hrtimer_cb_get_time(timer);
362 
363                         /*
364                          * FIXME: What we really want, is to stop this
365                          * timer completely and restart it in case the
366                          * SIG_IGN is removed. This is a non trivial
367                          * change which involves sighand locking
368                          * (sigh !), which we don't want to do late in
369                          * the release cycle.
370                          *
371                          * For now we just let timers with an interval
372                          * less than a jiffie expire every jiffie to
373                          * avoid softirq starvation in case of SIG_IGN
374                          * and a very small interval, which would put
375                          * the timer right back on the softirq pending
376                          * list. By moving now ahead of time we trick
377                          * hrtimer_forward() to expire the timer
378                          * later, while we still maintain the overrun
379                          * accuracy, but have some inconsistency in
380                          * the timer_gettime() case. This is at least
381                          * better than a starved softirq. A more
382                          * complex fix which solves also another related
383                          * inconsistency is already in the pipeline.
384                          */
385 #ifdef CONFIG_HIGH_RES_TIMERS
386                         {
387                                 ktime_t kj = NSEC_PER_SEC / HZ;
388 
389                                 if (timr->it_interval < kj)
390                                         now = ktime_add(now, kj);
391                         }
392 #endif
393                         timr->it_overrun += hrtimer_forward(timer, now,
394                                                             timr->it_interval);
395                         ret = HRTIMER_RESTART;
396                         ++timr->it_requeue_pending;
397                         timr->it_active = 1;
398                 }
399         }
400 
401         unlock_timer(timr, flags);
402         return ret;
403 }
404 
405 static struct pid *good_sigevent(sigevent_t * event)
406 {
407         struct pid *pid = task_tgid(current);
408         struct task_struct *rtn;
409 
410         switch (event->sigev_notify) {
411         case SIGEV_SIGNAL | SIGEV_THREAD_ID:
412                 pid = find_vpid(event->sigev_notify_thread_id);
413                 rtn = pid_task(pid, PIDTYPE_PID);
414                 if (!rtn || !same_thread_group(rtn, current))
415                         return NULL;
416                 /* FALLTHRU */
417         case SIGEV_SIGNAL:
418         case SIGEV_THREAD:
419                 if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
420                         return NULL;
421                 /* FALLTHRU */
422         case SIGEV_NONE:
423                 return pid;
424         default:
425                 return NULL;
426         }
427 }
428 
429 static struct k_itimer * alloc_posix_timer(void)
430 {
431         struct k_itimer *tmr;
432         tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
433         if (!tmr)
434                 return tmr;
435         if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
436                 kmem_cache_free(posix_timers_cache, tmr);
437                 return NULL;
438         }
439         clear_siginfo(&tmr->sigq->info);
440         return tmr;
441 }
442 
443 static void k_itimer_rcu_free(struct rcu_head *head)
444 {
445         struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu);
446 
447         kmem_cache_free(posix_timers_cache, tmr);
448 }
449 
450 #define IT_ID_SET       1
451 #define IT_ID_NOT_SET   0
452 static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
453 {
454         if (it_id_set) {
455                 unsigned long flags;
456                 spin_lock_irqsave(&hash_lock, flags);
457                 hlist_del_rcu(&tmr->t_hash);
458                 spin_unlock_irqrestore(&hash_lock, flags);
459         }
460         put_pid(tmr->it_pid);
461         sigqueue_free(tmr->sigq);
462         call_rcu(&tmr->it.rcu, k_itimer_rcu_free);
463 }
464 
465 static int common_timer_create(struct k_itimer *new_timer)
466 {
467         hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
468         return 0;
469 }
470 
471 /* Create a POSIX.1b interval timer. */
472 static int do_timer_create(clockid_t which_clock, struct sigevent *event,
473                            timer_t __user *created_timer_id)
474 {
475         const struct k_clock *kc = clockid_to_kclock(which_clock);
476         struct k_itimer *new_timer;
477         int error, new_timer_id;
478         int it_id_set = IT_ID_NOT_SET;
479 
480         if (!kc)
481                 return -EINVAL;
482         if (!kc->timer_create)
483                 return -EOPNOTSUPP;
484 
485         new_timer = alloc_posix_timer();
486         if (unlikely(!new_timer))
487                 return -EAGAIN;
488 
489         spin_lock_init(&new_timer->it_lock);
490         new_timer_id = posix_timer_add(new_timer);
491         if (new_timer_id < 0) {
492                 error = new_timer_id;
493                 goto out;
494         }
495 
496         it_id_set = IT_ID_SET;
497         new_timer->it_id = (timer_t) new_timer_id;
498         new_timer->it_clock = which_clock;
499         new_timer->kclock = kc;
500         new_timer->it_overrun = -1LL;
501 
502         if (event) {
503                 rcu_read_lock();
504                 new_timer->it_pid = get_pid(good_sigevent(event));
505                 rcu_read_unlock();
506                 if (!new_timer->it_pid) {
507                         error = -EINVAL;
508                         goto out;
509                 }
510                 new_timer->it_sigev_notify     = event->sigev_notify;
511                 new_timer->sigq->info.si_signo = event->sigev_signo;
512                 new_timer->sigq->info.si_value = event->sigev_value;
513         } else {
514                 new_timer->it_sigev_notify     = SIGEV_SIGNAL;
515                 new_timer->sigq->info.si_signo = SIGALRM;
516                 memset(&new_timer->sigq->info.si_value, 0, sizeof(sigval_t));
517                 new_timer->sigq->info.si_value.sival_int = new_timer->it_id;
518                 new_timer->it_pid = get_pid(task_tgid(current));
519         }
520 
521         new_timer->sigq->info.si_tid   = new_timer->it_id;
522         new_timer->sigq->info.si_code  = SI_TIMER;
523 
524         if (copy_to_user(created_timer_id,
525                          &new_timer_id, sizeof (new_timer_id))) {
526                 error = -EFAULT;
527                 goto out;
528         }
529 
530         error = kc->timer_create(new_timer);
531         if (error)
532                 goto out;
533 
534         spin_lock_irq(&current->sighand->siglock);
535         new_timer->it_signal = current->signal;
536         list_add(&new_timer->list, &current->signal->posix_timers);
537         spin_unlock_irq(&current->sighand->siglock);
538 
539         return 0;
540         /*
541          * In the case of the timer belonging to another task, after
542          * the task is unlocked, the timer is owned by the other task
543          * and may cease to exist at any time.  Don't use or modify
544          * new_timer after the unlock call.
545          */
546 out:
547         release_posix_timer(new_timer, it_id_set);
548         return error;
549 }
550 
551 SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
552                 struct sigevent __user *, timer_event_spec,
553                 timer_t __user *, created_timer_id)
554 {
555         if (timer_event_spec) {
556                 sigevent_t event;
557 
558                 if (copy_from_user(&event, timer_event_spec, sizeof (event)))
559                         return -EFAULT;
560                 return do_timer_create(which_clock, &event, created_timer_id);
561         }
562         return do_timer_create(which_clock, NULL, created_timer_id);
563 }
564 
565 #ifdef CONFIG_COMPAT
566 COMPAT_SYSCALL_DEFINE3(timer_create, clockid_t, which_clock,
567                        struct compat_sigevent __user *, timer_event_spec,
568                        timer_t __user *, created_timer_id)
569 {
570         if (timer_event_spec) {
571                 sigevent_t event;
572 
573                 if (get_compat_sigevent(&event, timer_event_spec))
574                         return -EFAULT;
575                 return do_timer_create(which_clock, &event, created_timer_id);
576         }
577         return do_timer_create(which_clock, NULL, created_timer_id);
578 }
579 #endif
580 
581 /*
582  * Locking issues: We need to protect the result of the id look up until
583  * we get the timer locked down so it is not deleted under us.  The
584  * removal is done under the idr spinlock so we use that here to bridge
585  * the find to the timer lock.  To avoid a dead lock, the timer id MUST
586  * be release with out holding the timer lock.
587  */
588 static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
589 {
590         struct k_itimer *timr;
591 
592         /*
593          * timer_t could be any type >= int and we want to make sure any
594          * @timer_id outside positive int range fails lookup.
595          */
596         if ((unsigned long long)timer_id > INT_MAX)
597                 return NULL;
598 
599         rcu_read_lock();
600         timr = posix_timer_by_id(timer_id);
601         if (timr) {
602                 spin_lock_irqsave(&timr->it_lock, *flags);
603                 if (timr->it_signal == current->signal) {
604                         rcu_read_unlock();
605                         return timr;
606                 }
607                 spin_unlock_irqrestore(&timr->it_lock, *flags);
608         }
609         rcu_read_unlock();
610 
611         return NULL;
612 }
613 
614 static ktime_t common_hrtimer_remaining(struct k_itimer *timr, ktime_t now)
615 {
616         struct hrtimer *timer = &timr->it.real.timer;
617 
618         return __hrtimer_expires_remaining_adjusted(timer, now);
619 }
620 
621 static s64 common_hrtimer_forward(struct k_itimer *timr, ktime_t now)
622 {
623         struct hrtimer *timer = &timr->it.real.timer;
624 
625         return hrtimer_forward(timer, now, timr->it_interval);
626 }
627 
628 /*
629  * Get the time remaining on a POSIX.1b interval timer.  This function
630  * is ALWAYS called with spin_lock_irq on the timer, thus it must not
631  * mess with irq.
632  *
633  * We have a couple of messes to clean up here.  First there is the case
634  * of a timer that has a requeue pending.  These timers should appear to
635  * be in the timer list with an expiry as if we were to requeue them
636  * now.
637  *
638  * The second issue is the SIGEV_NONE timer which may be active but is
639  * not really ever put in the timer list (to save system resources).
640  * This timer may be expired, and if so, we will do it here.  Otherwise
641  * it is the same as a requeue pending timer WRT to what we should
642  * report.
643  */
644 void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
645 {
646         const struct k_clock *kc = timr->kclock;
647         ktime_t now, remaining, iv;
648         struct timespec64 ts64;
649         bool sig_none;
650 
651         sig_none = timr->it_sigev_notify == SIGEV_NONE;
652         iv = timr->it_interval;
653 
654         /* interval timer ? */
655         if (iv) {
656                 cur_setting->it_interval = ktime_to_timespec64(iv);
657         } else if (!timr->it_active) {
658                 /*
659                  * SIGEV_NONE oneshot timers are never queued. Check them
660                  * below.
661                  */
662                 if (!sig_none)
663                         return;
664         }
665 
666         /*
667          * The timespec64 based conversion is suboptimal, but it's not
668          * worth to implement yet another callback.
669          */
670         kc->clock_get(timr->it_clock, &ts64);
671         now = timespec64_to_ktime(ts64);
672 
673         /*
674          * When a requeue is pending or this is a SIGEV_NONE timer move the
675          * expiry time forward by intervals, so expiry is > now.
676          */
677         if (iv && (timr->it_requeue_pending & REQUEUE_PENDING || sig_none))
678                 timr->it_overrun += kc->timer_forward(timr, now);
679 
680         remaining = kc->timer_remaining(timr, now);
681         /* Return 0 only, when the timer is expired and not pending */
682         if (remaining <= 0) {
683                 /*
684                  * A single shot SIGEV_NONE timer must return 0, when
685                  * it is expired !
686                  */
687                 if (!sig_none)
688                         cur_setting->it_value.tv_nsec = 1;
689         } else {
690                 cur_setting->it_value = ktime_to_timespec64(remaining);
691         }
692 }
693 
694 /* Get the time remaining on a POSIX.1b interval timer. */
695 static int do_timer_gettime(timer_t timer_id,  struct itimerspec64 *setting)
696 {
697         struct k_itimer *timr;
698         const struct k_clock *kc;
699         unsigned long flags;
700         int ret = 0;
701 
702         timr = lock_timer(timer_id, &flags);
703         if (!timr)
704                 return -EINVAL;
705 
706         memset(setting, 0, sizeof(*setting));
707         kc = timr->kclock;
708         if (WARN_ON_ONCE(!kc || !kc->timer_get))
709                 ret = -EINVAL;
710         else
711                 kc->timer_get(timr, setting);
712 
713         unlock_timer(timr, flags);
714         return ret;
715 }
716 
717 /* Get the time remaining on a POSIX.1b interval timer. */
718 SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
719                 struct __kernel_itimerspec __user *, setting)
720 {
721         struct itimerspec64 cur_setting;
722 
723         int ret = do_timer_gettime(timer_id, &cur_setting);
724         if (!ret) {
725                 if (put_itimerspec64(&cur_setting, setting))
726                         ret = -EFAULT;
727         }
728         return ret;
729 }
730 
731 #ifdef CONFIG_COMPAT_32BIT_TIME
732 
733 SYSCALL_DEFINE2(timer_gettime32, timer_t, timer_id,
734                 struct old_itimerspec32 __user *, setting)
735 {
736         struct itimerspec64 cur_setting;
737 
738         int ret = do_timer_gettime(timer_id, &cur_setting);
739         if (!ret) {
740                 if (put_old_itimerspec32(&cur_setting, setting))
741                         ret = -EFAULT;
742         }
743         return ret;
744 }
745 
746 #endif
747 
748 /*
749  * Get the number of overruns of a POSIX.1b interval timer.  This is to
750  * be the overrun of the timer last delivered.  At the same time we are
751  * accumulating overruns on the next timer.  The overrun is frozen when
752  * the signal is delivered, either at the notify time (if the info block
753  * is not queued) or at the actual delivery time (as we are informed by
754  * the call back to posixtimer_rearm().  So all we need to do is
755  * to pick up the frozen overrun.
756  */
757 SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
758 {
759         struct k_itimer *timr;
760         int overrun;
761         unsigned long flags;
762 
763         timr = lock_timer(timer_id, &flags);
764         if (!timr)
765                 return -EINVAL;
766 
767         overrun = timer_overrun_to_int(timr, 0);
768         unlock_timer(timr, flags);
769 
770         return overrun;
771 }
772 
773 static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
774                                bool absolute, bool sigev_none)
775 {
776         struct hrtimer *timer = &timr->it.real.timer;
777         enum hrtimer_mode mode;
778 
779         mode = absolute ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
780         /*
781          * Posix magic: Relative CLOCK_REALTIME timers are not affected by
782          * clock modifications, so they become CLOCK_MONOTONIC based under the
783          * hood. See hrtimer_init(). Update timr->kclock, so the generic
784          * functions which use timr->kclock->clock_get() work.
785          *
786          * Note: it_clock stays unmodified, because the next timer_set() might
787          * use ABSTIME, so it needs to switch back.
788          */
789         if (timr->it_clock == CLOCK_REALTIME)
790                 timr->kclock = absolute ? &clock_realtime : &clock_monotonic;
791 
792         hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
793         timr->it.real.timer.function = posix_timer_fn;
794 
795         if (!absolute)
796                 expires = ktime_add_safe(expires, timer->base->get_time());
797         hrtimer_set_expires(timer, expires);
798 
799         if (!sigev_none)
800                 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
801 }
802 
803 static int common_hrtimer_try_to_cancel(struct k_itimer *timr)
804 {
805         return hrtimer_try_to_cancel(&timr->it.real.timer);
806 }
807 
808 /* Set a POSIX.1b interval timer. */
809 int common_timer_set(struct k_itimer *timr, int flags,
810                      struct itimerspec64 *new_setting,
811                      struct itimerspec64 *old_setting)
812 {
813         const struct k_clock *kc = timr->kclock;
814         bool sigev_none;
815         ktime_t expires;
816 
817         if (old_setting)
818                 common_timer_get(timr, old_setting);
819 
820         /* Prevent rearming by clearing the interval */
821         timr->it_interval = 0;
822         /*
823          * Careful here. On SMP systems the timer expiry function could be
824          * active and spinning on timr->it_lock.
825          */
826         if (kc->timer_try_to_cancel(timr) < 0)
827                 return TIMER_RETRY;
828 
829         timr->it_active = 0;
830         timr->it_requeue_pending = (timr->it_requeue_pending + 2) &
831                 ~REQUEUE_PENDING;
832         timr->it_overrun_last = 0;
833 
834         /* Switch off the timer when it_value is zero */
835         if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
836                 return 0;
837 
838         timr->it_interval = timespec64_to_ktime(new_setting->it_interval);
839         expires = timespec64_to_ktime(new_setting->it_value);
840         sigev_none = timr->it_sigev_notify == SIGEV_NONE;
841 
842         kc->timer_arm(timr, expires, flags & TIMER_ABSTIME, sigev_none);
843         timr->it_active = !sigev_none;
844         return 0;
845 }
846 
847 static int do_timer_settime(timer_t timer_id, int flags,
848                             struct itimerspec64 *new_spec64,
849                             struct itimerspec64 *old_spec64)
850 {
851         const struct k_clock *kc;
852         struct k_itimer *timr;
853         unsigned long flag;
854         int error = 0;
855 
856         if (!timespec64_valid(&new_spec64->it_interval) ||
857             !timespec64_valid(&new_spec64->it_value))
858                 return -EINVAL;
859 
860         if (old_spec64)
861                 memset(old_spec64, 0, sizeof(*old_spec64));
862 retry:
863         timr = lock_timer(timer_id, &flag);
864         if (!timr)
865                 return -EINVAL;
866 
867         kc = timr->kclock;
868         if (WARN_ON_ONCE(!kc || !kc->timer_set))
869                 error = -EINVAL;
870         else
871                 error = kc->timer_set(timr, flags, new_spec64, old_spec64);
872 
873         unlock_timer(timr, flag);
874         if (error == TIMER_RETRY) {
875                 old_spec64 = NULL;      // We already got the old time...
876                 goto retry;
877         }
878 
879         return error;
880 }
881 
882 /* Set a POSIX.1b interval timer */
883 SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
884                 const struct __kernel_itimerspec __user *, new_setting,
885                 struct __kernel_itimerspec __user *, old_setting)
886 {
887         struct itimerspec64 new_spec, old_spec;
888         struct itimerspec64 *rtn = old_setting ? &old_spec : NULL;
889         int error = 0;
890 
891         if (!new_setting)
892                 return -EINVAL;
893 
894         if (get_itimerspec64(&new_spec, new_setting))
895                 return -EFAULT;
896 
897         error = do_timer_settime(timer_id, flags, &new_spec, rtn);
898         if (!error && old_setting) {
899                 if (put_itimerspec64(&old_spec, old_setting))
900                         error = -EFAULT;
901         }
902         return error;
903 }
904 
905 #ifdef CONFIG_COMPAT_32BIT_TIME
906 SYSCALL_DEFINE4(timer_settime32, timer_t, timer_id, int, flags,
907                 struct old_itimerspec32 __user *, new,
908                 struct old_itimerspec32 __user *, old)
909 {
910         struct itimerspec64 new_spec, old_spec;
911         struct itimerspec64 *rtn = old ? &old_spec : NULL;
912         int error = 0;
913 
914         if (!new)
915                 return -EINVAL;
916         if (get_old_itimerspec32(&new_spec, new))
917                 return -EFAULT;
918 
919         error = do_timer_settime(timer_id, flags, &new_spec, rtn);
920         if (!error && old) {
921                 if (put_old_itimerspec32(&old_spec, old))
922                         error = -EFAULT;
923         }
924         return error;
925 }
926 #endif
927 
928 int common_timer_del(struct k_itimer *timer)
929 {
930         const struct k_clock *kc = timer->kclock;
931 
932         timer->it_interval = 0;
933         if (kc->timer_try_to_cancel(timer) < 0)
934                 return TIMER_RETRY;
935         timer->it_active = 0;
936         return 0;
937 }
938 
939 static inline int timer_delete_hook(struct k_itimer *timer)
940 {
941         const struct k_clock *kc = timer->kclock;
942 
943         if (WARN_ON_ONCE(!kc || !kc->timer_del))
944                 return -EINVAL;
945         return kc->timer_del(timer);
946 }
947 
948 /* Delete a POSIX.1b interval timer. */
949 SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
950 {
951         struct k_itimer *timer;
952         unsigned long flags;
953 
954 retry_delete:
955         timer = lock_timer(timer_id, &flags);
956         if (!timer)
957                 return -EINVAL;
958 
959         if (timer_delete_hook(timer) == TIMER_RETRY) {
960                 unlock_timer(timer, flags);
961                 goto retry_delete;
962         }
963 
964         spin_lock(&current->sighand->siglock);
965         list_del(&timer->list);
966         spin_unlock(&current->sighand->siglock);
967         /*
968          * This keeps any tasks waiting on the spin lock from thinking
969          * they got something (see the lock code above).
970          */
971         timer->it_signal = NULL;
972 
973         unlock_timer(timer, flags);
974         release_posix_timer(timer, IT_ID_SET);
975         return 0;
976 }
977 
978 /*
979  * return timer owned by the process, used by exit_itimers
980  */
981 static void itimer_delete(struct k_itimer *timer)
982 {
983         unsigned long flags;
984 
985 retry_delete:
986         spin_lock_irqsave(&timer->it_lock, flags);
987 
988         if (timer_delete_hook(timer) == TIMER_RETRY) {
989                 unlock_timer(timer, flags);
990                 goto retry_delete;
991         }
992         list_del(&timer->list);
993         /*
994          * This keeps any tasks waiting on the spin lock from thinking
995          * they got something (see the lock code above).
996          */
997         timer->it_signal = NULL;
998 
999         unlock_timer(timer, flags);
1000         release_posix_timer(timer, IT_ID_SET);
1001 }
1002 
1003 /*
1004  * This is called by do_exit or de_thread, only when there are no more
1005  * references to the shared signal_struct.
1006  */
1007 void exit_itimers(struct signal_struct *sig)
1008 {
1009         struct k_itimer *tmr;
1010 
1011         while (!list_empty(&sig->posix_timers)) {
1012                 tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
1013                 itimer_delete(tmr);
1014         }
1015 }
1016 
1017 SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
1018                 const struct __kernel_timespec __user *, tp)
1019 {
1020         const struct k_clock *kc = clockid_to_kclock(which_clock);
1021         struct timespec64 new_tp;
1022 
1023         if (!kc || !kc->clock_set)
1024                 return -EINVAL;
1025 
1026         if (get_timespec64(&new_tp, tp))
1027                 return -EFAULT;
1028 
1029         return kc->clock_set(which_clock, &new_tp);
1030 }
1031 
1032 SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
1033                 struct __kernel_timespec __user *, tp)
1034 {
1035         const struct k_clock *kc = clockid_to_kclock(which_clock);
1036         struct timespec64 kernel_tp;
1037         int error;
1038 
1039         if (!kc)
1040                 return -EINVAL;
1041 
1042         error = kc->clock_get(which_clock, &kernel_tp);
1043 
1044         if (!error && put_timespec64(&kernel_tp, tp))
1045                 error = -EFAULT;
1046 
1047         return error;
1048 }
1049 
1050 int do_clock_adjtime(const clockid_t which_clock, struct __kernel_timex * ktx)
1051 {
1052         const struct k_clock *kc = clockid_to_kclock(which_clock);
1053 
1054         if (!kc)
1055                 return -EINVAL;
1056         if (!kc->clock_adj)
1057                 return -EOPNOTSUPP;
1058 
1059         return kc->clock_adj(which_clock, ktx);
1060 }
1061 
1062 SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
1063                 struct __kernel_timex __user *, utx)
1064 {
1065         struct __kernel_timex ktx;
1066         int err;
1067 
1068         if (copy_from_user(&ktx, utx, sizeof(ktx)))
1069                 return -EFAULT;
1070 
1071         err = do_clock_adjtime(which_clock, &ktx);
1072 
1073         if (err >= 0 && copy_to_user(utx, &ktx, sizeof(ktx)))
1074                 return -EFAULT;
1075 
1076         return err;
1077 }
1078 
1079 SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
1080                 struct __kernel_timespec __user *, tp)
1081 {
1082         const struct k_clock *kc = clockid_to_kclock(which_clock);
1083         struct timespec64 rtn_tp;
1084         int error;
1085 
1086         if (!kc)
1087                 return -EINVAL;
1088 
1089         error = kc->clock_getres(which_clock, &rtn_tp);
1090 
1091         if (!error && tp && put_timespec64(&rtn_tp, tp))
1092                 error = -EFAULT;
1093 
1094         return error;
1095 }
1096 
1097 #ifdef CONFIG_COMPAT_32BIT_TIME
1098 
1099 SYSCALL_DEFINE2(clock_settime32, clockid_t, which_clock,
1100                 struct old_timespec32 __user *, tp)
1101 {
1102         const struct k_clock *kc = clockid_to_kclock(which_clock);
1103         struct timespec64 ts;
1104 
1105         if (!kc || !kc->clock_set)
1106                 return -EINVAL;
1107 
1108         if (get_old_timespec32(&ts, tp))
1109                 return -EFAULT;
1110 
1111         return kc->clock_set(which_clock, &ts);
1112 }
1113 
1114 SYSCALL_DEFINE2(clock_gettime32, clockid_t, which_clock,
1115                 struct old_timespec32 __user *, tp)
1116 {
1117         const struct k_clock *kc = clockid_to_kclock(which_clock);
1118         struct timespec64 ts;
1119         int err;
1120 
1121         if (!kc)
1122                 return -EINVAL;
1123 
1124         err = kc->clock_get(which_clock, &ts);
1125 
1126         if (!err && put_old_timespec32(&ts, tp))
1127                 err = -EFAULT;
1128 
1129         return err;
1130 }
1131 
1132 SYSCALL_DEFINE2(clock_adjtime32, clockid_t, which_clock,
1133                 struct old_timex32 __user *, utp)
1134 {
1135         struct __kernel_timex ktx;
1136         int err;
1137 
1138         err = get_old_timex32(&ktx, utp);
1139         if (err)
1140                 return err;
1141 
1142         err = do_clock_adjtime(which_clock, &ktx);
1143 
1144         if (err >= 0)
1145                 err = put_old_timex32(utp, &ktx);
1146 
1147         return err;
1148 }
1149 
1150 SYSCALL_DEFINE2(clock_getres_time32, clockid_t, which_clock,
1151                 struct old_timespec32 __user *, tp)
1152 {
1153         const struct k_clock *kc = clockid_to_kclock(which_clock);
1154         struct timespec64 ts;
1155         int err;
1156 
1157         if (!kc)
1158                 return -EINVAL;
1159 
1160         err = kc->clock_getres(which_clock, &ts);
1161         if (!err && tp && put_old_timespec32(&ts, tp))
1162                 return -EFAULT;
1163 
1164         return err;
1165 }
1166 
1167 #endif
1168 
1169 /*
1170  * nanosleep for monotonic and realtime clocks
1171  */
1172 static int common_nsleep(const clockid_t which_clock, int flags,
1173                          const struct timespec64 *rqtp)
1174 {
1175         return hrtimer_nanosleep(rqtp, flags & TIMER_ABSTIME ?
1176                                  HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
1177                                  which_clock);
1178 }
1179 
1180 SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
1181                 const struct __kernel_timespec __user *, rqtp,
1182                 struct __kernel_timespec __user *, rmtp)
1183 {
1184         const struct k_clock *kc = clockid_to_kclock(which_clock);
1185         struct timespec64 t;
1186 
1187         if (!kc)
1188                 return -EINVAL;
1189         if (!kc->nsleep)
1190                 return -EOPNOTSUPP;
1191 
1192         if (get_timespec64(&t, rqtp))
1193                 return -EFAULT;
1194 
1195         if (!timespec64_valid(&t))
1196                 return -EINVAL;
1197         if (flags & TIMER_ABSTIME)
1198                 rmtp = NULL;
1199         current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
1200         current->restart_block.nanosleep.rmtp = rmtp;
1201 
1202         return kc->nsleep(which_clock, flags, &t);
1203 }
1204 
1205 #ifdef CONFIG_COMPAT_32BIT_TIME
1206 
1207 SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
1208                 struct old_timespec32 __user *, rqtp,
1209                 struct old_timespec32 __user *, rmtp)
1210 {
1211         const struct k_clock *kc = clockid_to_kclock(which_clock);
1212         struct timespec64 t;
1213 
1214         if (!kc)
1215                 return -EINVAL;
1216         if (!kc->nsleep)
1217                 return -EOPNOTSUPP;
1218 
1219         if (get_old_timespec32(&t, rqtp))
1220                 return -EFAULT;
1221 
1222         if (!timespec64_valid(&t))
1223                 return -EINVAL;
1224         if (flags & TIMER_ABSTIME)
1225                 rmtp = NULL;
1226         current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
1227         current->restart_block.nanosleep.compat_rmtp = rmtp;
1228 
1229         return kc->nsleep(which_clock, flags, &t);
1230 }
1231 
1232 #endif
1233 
1234 static const struct k_clock clock_realtime = {
1235         .clock_getres           = posix_get_hrtimer_res,
1236         .clock_get              = posix_clock_realtime_get,
1237         .clock_set              = posix_clock_realtime_set,
1238         .clock_adj              = posix_clock_realtime_adj,
1239         .nsleep                 = common_nsleep,
1240         .timer_create           = common_timer_create,
1241         .timer_set              = common_timer_set,
1242         .timer_get              = common_timer_get,
1243         .timer_del              = common_timer_del,
1244         .timer_rearm            = common_hrtimer_rearm,
1245         .timer_forward          = common_hrtimer_forward,
1246         .timer_remaining        = common_hrtimer_remaining,
1247         .timer_try_to_cancel    = common_hrtimer_try_to_cancel,
1248         .timer_arm              = common_hrtimer_arm,
1249 };
1250 
1251 static const struct k_clock clock_monotonic = {
1252         .clock_getres           = posix_get_hrtimer_res,
1253         .clock_get              = posix_ktime_get_ts,
1254         .nsleep                 = common_nsleep,
1255         .timer_create           = common_timer_create,
1256         .timer_set              = common_timer_set,
1257         .timer_get              = common_timer_get,
1258         .timer_del              = common_timer_del,
1259         .timer_rearm            = common_hrtimer_rearm,
1260         .timer_forward          = common_hrtimer_forward,
1261         .timer_remaining        = common_hrtimer_remaining,
1262         .timer_try_to_cancel    = common_hrtimer_try_to_cancel,
1263         .timer_arm              = common_hrtimer_arm,
1264 };
1265 
1266 static const struct k_clock clock_monotonic_raw = {
1267         .clock_getres           = posix_get_hrtimer_res,
1268         .clock_get              = posix_get_monotonic_raw,
1269 };
1270 
1271 static const struct k_clock clock_realtime_coarse = {
1272         .clock_getres           = posix_get_coarse_res,
1273         .clock_get              = posix_get_realtime_coarse,
1274 };
1275 
1276 static const struct k_clock clock_monotonic_coarse = {
1277         .clock_getres           = posix_get_coarse_res,
1278         .clock_get              = posix_get_monotonic_coarse,
1279 };
1280 
1281 static const struct k_clock clock_tai = {
1282         .clock_getres           = posix_get_hrtimer_res,
1283         .clock_get              = posix_get_tai,
1284         .nsleep                 = common_nsleep,
1285         .timer_create           = common_timer_create,
1286         .timer_set              = common_timer_set,
1287         .timer_get              = common_timer_get,
1288         .timer_del              = common_timer_del,
1289         .timer_rearm            = common_hrtimer_rearm,
1290         .timer_forward          = common_hrtimer_forward,
1291         .timer_remaining        = common_hrtimer_remaining,
1292         .timer_try_to_cancel    = common_hrtimer_try_to_cancel,
1293         .timer_arm              = common_hrtimer_arm,
1294 };
1295 
1296 static const struct k_clock clock_boottime = {
1297         .clock_getres           = posix_get_hrtimer_res,
1298         .clock_get              = posix_get_boottime,
1299         .nsleep                 = common_nsleep,
1300         .timer_create           = common_timer_create,
1301         .timer_set              = common_timer_set,
1302         .timer_get              = common_timer_get,
1303         .timer_del              = common_timer_del,
1304         .timer_rearm            = common_hrtimer_rearm,
1305         .timer_forward          = common_hrtimer_forward,
1306         .timer_remaining        = common_hrtimer_remaining,
1307         .timer_try_to_cancel    = common_hrtimer_try_to_cancel,
1308         .timer_arm              = common_hrtimer_arm,
1309 };
1310 
1311 static const struct k_clock * const posix_clocks[] = {
1312         [CLOCK_REALTIME]                = &clock_realtime,
1313         [CLOCK_MONOTONIC]               = &clock_monotonic,
1314         [CLOCK_PROCESS_CPUTIME_ID]      = &clock_process,
1315         [CLOCK_THREAD_CPUTIME_ID]       = &clock_thread,
1316         [CLOCK_MONOTONIC_RAW]           = &clock_monotonic_raw,
1317         [CLOCK_REALTIME_COARSE]         = &clock_realtime_coarse,
1318         [CLOCK_MONOTONIC_COARSE]        = &clock_monotonic_coarse,
1319         [CLOCK_BOOTTIME]                = &clock_boottime,
1320         [CLOCK_REALTIME_ALARM]          = &alarm_clock,
1321         [CLOCK_BOOTTIME_ALARM]          = &alarm_clock,
1322         [CLOCK_TAI]                     = &clock_tai,
1323 };
1324 
1325 static const struct k_clock *clockid_to_kclock(const clockid_t id)
1326 {
1327         clockid_t idx = id;
1328 
1329         if (id < 0) {
1330                 return (id & CLOCKFD_MASK) == CLOCKFD ?
1331                         &clock_posix_dynamic : &clock_posix_cpu;
1332         }
1333 
1334         if (id >= ARRAY_SIZE(posix_clocks))
1335                 return NULL;
1336 
1337         return posix_clocks[array_index_nospec(idx, ARRAY_SIZE(posix_clocks))];
1338 }
1339 

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