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/compat.h>
13 #include <linux/compiler.h>
14 #include <linux/init.h>
15 #include <linux/jhash.h>
16 #include <linux/interrupt.h>
17 #include <linux/list.h>
18 #include <linux/memblock.h>
19 #include <linux/nospec.h>
20 #include <linux/posix-clock.h>
21 #include <linux/posix-timers.h>
22 #include <linux/prctl.h>
23 #include <linux/sched/task.h>
24 #include <linux/slab.h>
25 #include <linux/syscalls.h>
26 #include <linux/time.h>
27 #include <linux/time_namespace.h>
28 #include <linux/uaccess.h>
29
30 #include "timekeeping.h"
31 #include "posix-timers.h"
32
33 static struct kmem_cache *posix_timers_cache;
34
35 /*
36 * Timers are managed in a hash table for lockless lookup. The hash key is
37 * constructed from current::signal and the timer ID and the timer is
38 * matched against current::signal and the timer ID when walking the hash
39 * bucket list.
40 *
41 * This allows checkpoint/restore to reconstruct the exact timer IDs for
42 * a process.
43 */
44 struct timer_hash_bucket {
45 spinlock_t lock;
46 struct hlist_head head;
47 };
48
49 static struct {
50 struct timer_hash_bucket *buckets;
51 unsigned long mask;
52 } __timer_data __ro_after_init __aligned(2*sizeof(long));
53
54 #define timer_buckets (__timer_data.buckets)
55 #define timer_hashmask (__timer_data.mask)
56
57 static const struct k_clock * const posix_clocks[];
58 static const struct k_clock *clockid_to_kclock(const clockid_t id);
59 static const struct k_clock clock_realtime, clock_monotonic;
60
61 #define TIMER_ANY_ID INT_MIN
62
63 /* SIGEV_THREAD_ID cannot share a bit with the other SIGEV values. */
64 #if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
65 ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
66 #error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
67 #endif
68
69 static struct k_itimer *__lock_timer(timer_t timer_id);
70
71 #define lock_timer(tid) \
72 ({ struct k_itimer *__timr; \
73 __cond_lock(&__timr->it_lock, __timr = __lock_timer(tid)); \
74 __timr; \
75 })
76
unlock_timer(struct k_itimer * timr)77 static inline void unlock_timer(struct k_itimer *timr)
78 {
79 if (likely((timr)))
80 spin_unlock_irq(&timr->it_lock);
81 }
82
83 #define scoped_timer_get_or_fail(_id) \
84 scoped_cond_guard(lock_timer, return -EINVAL, _id)
85
86 #define scoped_timer (scope)
87
88 DEFINE_CLASS(lock_timer, struct k_itimer *, unlock_timer(_T), __lock_timer(id), timer_t id);
89 DEFINE_CLASS_IS_COND_GUARD(lock_timer);
90
hash_bucket(struct signal_struct * sig,unsigned int nr)91 static struct timer_hash_bucket *hash_bucket(struct signal_struct *sig, unsigned int nr)
92 {
93 return &timer_buckets[jhash2((u32 *)&sig, sizeof(sig) / sizeof(u32), nr) & timer_hashmask];
94 }
95
posix_timer_by_id(timer_t id)96 static struct k_itimer *posix_timer_by_id(timer_t id)
97 {
98 struct signal_struct *sig = current->signal;
99 struct timer_hash_bucket *bucket = hash_bucket(sig, id);
100 struct k_itimer *timer;
101
102 hlist_for_each_entry_rcu(timer, &bucket->head, t_hash) {
103 /* timer->it_signal can be set concurrently */
104 if ((READ_ONCE(timer->it_signal) == sig) && (timer->it_id == id))
105 return timer;
106 }
107 return NULL;
108 }
109
posix_sig_owner(const struct k_itimer * timer)110 static inline struct signal_struct *posix_sig_owner(const struct k_itimer *timer)
111 {
112 unsigned long val = (unsigned long)timer->it_signal;
113
114 /*
115 * Mask out bit 0, which acts as invalid marker to prevent
116 * posix_timer_by_id() detecting it as valid.
117 */
118 return (struct signal_struct *)(val & ~1UL);
119 }
120
posix_timer_hashed(struct timer_hash_bucket * bucket,struct signal_struct * sig,timer_t id)121 static bool posix_timer_hashed(struct timer_hash_bucket *bucket, struct signal_struct *sig,
122 timer_t id)
123 {
124 struct hlist_head *head = &bucket->head;
125 struct k_itimer *timer;
126
127 hlist_for_each_entry_rcu(timer, head, t_hash, lockdep_is_held(&bucket->lock)) {
128 if ((posix_sig_owner(timer) == sig) && (timer->it_id == id))
129 return true;
130 }
131 return false;
132 }
133
posix_timer_add_at(struct k_itimer * timer,struct signal_struct * sig,unsigned int id)134 static bool posix_timer_add_at(struct k_itimer *timer, struct signal_struct *sig, unsigned int id)
135 {
136 struct timer_hash_bucket *bucket = hash_bucket(sig, id);
137
138 scoped_guard (spinlock, &bucket->lock) {
139 /*
140 * Validate under the lock as this could have raced against
141 * another thread ending up with the same ID, which is
142 * highly unlikely, but possible.
143 */
144 if (!posix_timer_hashed(bucket, sig, id)) {
145 /*
146 * Set the timer ID and the signal pointer to make
147 * it identifiable in the hash table. The signal
148 * pointer has bit 0 set to indicate that it is not
149 * yet fully initialized. posix_timer_hashed()
150 * masks this bit out, but the syscall lookup fails
151 * to match due to it being set. This guarantees
152 * that there can't be duplicate timer IDs handed
153 * out.
154 */
155 timer->it_id = (timer_t)id;
156 timer->it_signal = (struct signal_struct *)((unsigned long)sig | 1UL);
157 hlist_add_head_rcu(&timer->t_hash, &bucket->head);
158 return true;
159 }
160 }
161 return false;
162 }
163
posix_timer_add(struct k_itimer * timer,int req_id)164 static int posix_timer_add(struct k_itimer *timer, int req_id)
165 {
166 struct signal_struct *sig = current->signal;
167
168 if (unlikely(req_id != TIMER_ANY_ID)) {
169 if (!posix_timer_add_at(timer, sig, req_id))
170 return -EBUSY;
171
172 /*
173 * Move the ID counter past the requested ID, so that after
174 * switching back to normal mode the IDs are outside of the
175 * exact allocated region. That avoids ID collisions on the
176 * next regular timer_create() invocations.
177 */
178 atomic_set(&sig->next_posix_timer_id, req_id + 1);
179 return req_id;
180 }
181
182 for (unsigned int cnt = 0; cnt <= INT_MAX; cnt++) {
183 /* Get the next timer ID and clamp it to positive space */
184 unsigned int id = atomic_fetch_inc(&sig->next_posix_timer_id) & INT_MAX;
185
186 if (posix_timer_add_at(timer, sig, id))
187 return id;
188 cond_resched();
189 }
190 /* POSIX return code when no timer ID could be allocated */
191 return -EAGAIN;
192 }
193
posix_get_realtime_timespec(clockid_t which_clock,struct timespec64 * tp)194 static int posix_get_realtime_timespec(clockid_t which_clock, struct timespec64 *tp)
195 {
196 ktime_get_real_ts64(tp);
197 return 0;
198 }
199
posix_get_realtime_ktime(clockid_t which_clock)200 static ktime_t posix_get_realtime_ktime(clockid_t which_clock)
201 {
202 return ktime_get_real();
203 }
204
posix_clock_realtime_set(const clockid_t which_clock,const struct timespec64 * tp)205 static int posix_clock_realtime_set(const clockid_t which_clock,
206 const struct timespec64 *tp)
207 {
208 return do_sys_settimeofday64(tp, NULL);
209 }
210
posix_clock_realtime_adj(const clockid_t which_clock,struct __kernel_timex * t)211 static int posix_clock_realtime_adj(const clockid_t which_clock,
212 struct __kernel_timex *t)
213 {
214 return do_adjtimex(t);
215 }
216
posix_get_monotonic_timespec(clockid_t which_clock,struct timespec64 * tp)217 static int posix_get_monotonic_timespec(clockid_t which_clock, struct timespec64 *tp)
218 {
219 ktime_get_ts64(tp);
220 timens_add_monotonic(tp);
221 return 0;
222 }
223
posix_get_monotonic_ktime(clockid_t which_clock)224 static ktime_t posix_get_monotonic_ktime(clockid_t which_clock)
225 {
226 return ktime_get();
227 }
228
posix_get_monotonic_raw(clockid_t which_clock,struct timespec64 * tp)229 static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec64 *tp)
230 {
231 ktime_get_raw_ts64(tp);
232 timens_add_monotonic(tp);
233 return 0;
234 }
235
posix_get_realtime_coarse(clockid_t which_clock,struct timespec64 * tp)236 static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec64 *tp)
237 {
238 ktime_get_coarse_real_ts64(tp);
239 return 0;
240 }
241
posix_get_monotonic_coarse(clockid_t which_clock,struct timespec64 * tp)242 static int posix_get_monotonic_coarse(clockid_t which_clock,
243 struct timespec64 *tp)
244 {
245 ktime_get_coarse_ts64(tp);
246 timens_add_monotonic(tp);
247 return 0;
248 }
249
posix_get_coarse_res(const clockid_t which_clock,struct timespec64 * tp)250 static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *tp)
251 {
252 *tp = ktime_to_timespec64(KTIME_LOW_RES);
253 return 0;
254 }
255
posix_get_boottime_timespec(const clockid_t which_clock,struct timespec64 * tp)256 static int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
257 {
258 ktime_get_boottime_ts64(tp);
259 timens_add_boottime(tp);
260 return 0;
261 }
262
posix_get_boottime_ktime(const clockid_t which_clock)263 static ktime_t posix_get_boottime_ktime(const clockid_t which_clock)
264 {
265 return ktime_get_boottime();
266 }
267
posix_get_tai_timespec(clockid_t which_clock,struct timespec64 * tp)268 static int posix_get_tai_timespec(clockid_t which_clock, struct timespec64 *tp)
269 {
270 ktime_get_clocktai_ts64(tp);
271 return 0;
272 }
273
posix_get_tai_ktime(clockid_t which_clock)274 static ktime_t posix_get_tai_ktime(clockid_t which_clock)
275 {
276 return ktime_get_clocktai();
277 }
278
posix_get_hrtimer_res(clockid_t which_clock,struct timespec64 * tp)279 static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
280 {
281 tp->tv_sec = 0;
282 tp->tv_nsec = hrtimer_resolution;
283 return 0;
284 }
285
init_posix_timers(void)286 static __init int init_posix_timers(void)
287 {
288 posix_timers_cache = kmem_cache_create("posix_timers_cache", sizeof(struct k_itimer),
289 __alignof__(struct k_itimer), SLAB_ACCOUNT, NULL);
290 return 0;
291 }
292 __initcall(init_posix_timers);
293
294 /*
295 * The siginfo si_overrun field and the return value of timer_getoverrun(2)
296 * are of type int. Clamp the overrun value to INT_MAX
297 */
timer_overrun_to_int(struct k_itimer * timr)298 static inline int timer_overrun_to_int(struct k_itimer *timr)
299 {
300 if (timr->it_overrun_last > (s64)INT_MAX)
301 return INT_MAX;
302
303 return (int)timr->it_overrun_last;
304 }
305
common_hrtimer_rearm(struct k_itimer * timr)306 static void common_hrtimer_rearm(struct k_itimer *timr)
307 {
308 struct hrtimer *timer = &timr->it.real.timer;
309
310 timr->it_overrun += hrtimer_forward(timer, timer->base->get_time(),
311 timr->it_interval);
312 hrtimer_restart(timer);
313 }
314
__posixtimer_deliver_signal(struct kernel_siginfo * info,struct k_itimer * timr)315 static bool __posixtimer_deliver_signal(struct kernel_siginfo *info, struct k_itimer *timr)
316 {
317 guard(spinlock)(&timr->it_lock);
318
319 /*
320 * Check if the timer is still alive or whether it got modified
321 * since the signal was queued. In either case, don't rearm and
322 * drop the signal.
323 */
324 if (timr->it_signal_seq != timr->it_sigqueue_seq || WARN_ON_ONCE(!posixtimer_valid(timr)))
325 return false;
326
327 if (!timr->it_interval || WARN_ON_ONCE(timr->it_status != POSIX_TIMER_REQUEUE_PENDING))
328 return true;
329
330 timr->kclock->timer_rearm(timr);
331 timr->it_status = POSIX_TIMER_ARMED;
332 timr->it_overrun_last = timr->it_overrun;
333 timr->it_overrun = -1LL;
334 ++timr->it_signal_seq;
335 info->si_overrun = timer_overrun_to_int(timr);
336 return true;
337 }
338
339 /*
340 * This function is called from the signal delivery code. It decides
341 * whether the signal should be dropped and rearms interval timers. The
342 * timer can be unconditionally accessed as there is a reference held on
343 * it.
344 */
posixtimer_deliver_signal(struct kernel_siginfo * info,struct sigqueue * timer_sigq)345 bool posixtimer_deliver_signal(struct kernel_siginfo *info, struct sigqueue *timer_sigq)
346 {
347 struct k_itimer *timr = container_of(timer_sigq, struct k_itimer, sigq);
348 bool ret;
349
350 /*
351 * Release siglock to ensure proper locking order versus
352 * timr::it_lock. Keep interrupts disabled.
353 */
354 spin_unlock(¤t->sighand->siglock);
355
356 ret = __posixtimer_deliver_signal(info, timr);
357
358 /* Drop the reference which was acquired when the signal was queued */
359 posixtimer_putref(timr);
360
361 spin_lock(¤t->sighand->siglock);
362 return ret;
363 }
364
posix_timer_queue_signal(struct k_itimer * timr)365 void posix_timer_queue_signal(struct k_itimer *timr)
366 {
367 lockdep_assert_held(&timr->it_lock);
368
369 if (!posixtimer_valid(timr))
370 return;
371
372 timr->it_status = timr->it_interval ? POSIX_TIMER_REQUEUE_PENDING : POSIX_TIMER_DISARMED;
373 posixtimer_send_sigqueue(timr);
374 }
375
376 /*
377 * This function gets called when a POSIX.1b interval timer expires from
378 * the HRTIMER interrupt (soft interrupt on RT kernels).
379 *
380 * Handles CLOCK_REALTIME, CLOCK_MONOTONIC, CLOCK_BOOTTIME and CLOCK_TAI
381 * based timers.
382 */
posix_timer_fn(struct hrtimer * timer)383 static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
384 {
385 struct k_itimer *timr = container_of(timer, struct k_itimer, it.real.timer);
386
387 guard(spinlock_irqsave)(&timr->it_lock);
388 posix_timer_queue_signal(timr);
389 return HRTIMER_NORESTART;
390 }
391
posixtimer_create_prctl(unsigned long ctrl)392 long posixtimer_create_prctl(unsigned long ctrl)
393 {
394 switch (ctrl) {
395 case PR_TIMER_CREATE_RESTORE_IDS_OFF:
396 current->signal->timer_create_restore_ids = 0;
397 return 0;
398 case PR_TIMER_CREATE_RESTORE_IDS_ON:
399 current->signal->timer_create_restore_ids = 1;
400 return 0;
401 case PR_TIMER_CREATE_RESTORE_IDS_GET:
402 return current->signal->timer_create_restore_ids;
403 }
404 return -EINVAL;
405 }
406
good_sigevent(sigevent_t * event)407 static struct pid *good_sigevent(sigevent_t * event)
408 {
409 struct pid *pid = task_tgid(current);
410 struct task_struct *rtn;
411
412 switch (event->sigev_notify) {
413 case SIGEV_SIGNAL | SIGEV_THREAD_ID:
414 pid = find_vpid(event->sigev_notify_thread_id);
415 rtn = pid_task(pid, PIDTYPE_PID);
416 if (!rtn || !same_thread_group(rtn, current))
417 return NULL;
418 fallthrough;
419 case SIGEV_SIGNAL:
420 case SIGEV_THREAD:
421 if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
422 return NULL;
423 fallthrough;
424 case SIGEV_NONE:
425 return pid;
426 default:
427 return NULL;
428 }
429 }
430
alloc_posix_timer(void)431 static struct k_itimer *alloc_posix_timer(void)
432 {
433 struct k_itimer *tmr;
434
435 if (unlikely(!posix_timers_cache))
436 return NULL;
437
438 tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
439 if (!tmr)
440 return tmr;
441
442 if (unlikely(!posixtimer_init_sigqueue(&tmr->sigq))) {
443 kmem_cache_free(posix_timers_cache, tmr);
444 return NULL;
445 }
446 rcuref_init(&tmr->rcuref, 1);
447 return tmr;
448 }
449
posixtimer_free_timer(struct k_itimer * tmr)450 void posixtimer_free_timer(struct k_itimer *tmr)
451 {
452 put_pid(tmr->it_pid);
453 if (tmr->sigq.ucounts)
454 dec_rlimit_put_ucounts(tmr->sigq.ucounts, UCOUNT_RLIMIT_SIGPENDING);
455 kfree_rcu(tmr, rcu);
456 }
457
posix_timer_unhash_and_free(struct k_itimer * tmr)458 static void posix_timer_unhash_and_free(struct k_itimer *tmr)
459 {
460 struct timer_hash_bucket *bucket = hash_bucket(posix_sig_owner(tmr), tmr->it_id);
461
462 scoped_guard (spinlock, &bucket->lock)
463 hlist_del_rcu(&tmr->t_hash);
464 posixtimer_putref(tmr);
465 }
466
common_timer_create(struct k_itimer * new_timer)467 static int common_timer_create(struct k_itimer *new_timer)
468 {
469 hrtimer_setup(&new_timer->it.real.timer, posix_timer_fn, new_timer->it_clock, 0);
470 return 0;
471 }
472
473 /* Create a POSIX.1b interval timer. */
do_timer_create(clockid_t which_clock,struct sigevent * event,timer_t __user * created_timer_id)474 static int do_timer_create(clockid_t which_clock, struct sigevent *event,
475 timer_t __user *created_timer_id)
476 {
477 const struct k_clock *kc = clockid_to_kclock(which_clock);
478 timer_t req_id = TIMER_ANY_ID;
479 struct k_itimer *new_timer;
480 int error, new_timer_id;
481
482 if (!kc)
483 return -EINVAL;
484 if (!kc->timer_create)
485 return -EOPNOTSUPP;
486
487 new_timer = alloc_posix_timer();
488 if (unlikely(!new_timer))
489 return -EAGAIN;
490
491 spin_lock_init(&new_timer->it_lock);
492
493 /* Special case for CRIU to restore timers with a given timer ID. */
494 if (unlikely(current->signal->timer_create_restore_ids)) {
495 if (copy_from_user(&req_id, created_timer_id, sizeof(req_id)))
496 return -EFAULT;
497 /* Valid IDs are 0..INT_MAX */
498 if ((unsigned int)req_id > INT_MAX)
499 return -EINVAL;
500 }
501
502 /*
503 * Add the timer to the hash table. The timer is not yet valid
504 * after insertion, but has a unique ID allocated.
505 */
506 new_timer_id = posix_timer_add(new_timer, req_id);
507 if (new_timer_id < 0) {
508 posixtimer_free_timer(new_timer);
509 return new_timer_id;
510 }
511
512 new_timer->it_clock = which_clock;
513 new_timer->kclock = kc;
514 new_timer->it_overrun = -1LL;
515
516 if (event) {
517 scoped_guard (rcu)
518 new_timer->it_pid = get_pid(good_sigevent(event));
519 if (!new_timer->it_pid) {
520 error = -EINVAL;
521 goto out;
522 }
523 new_timer->it_sigev_notify = event->sigev_notify;
524 new_timer->sigq.info.si_signo = event->sigev_signo;
525 new_timer->sigq.info.si_value = event->sigev_value;
526 } else {
527 new_timer->it_sigev_notify = SIGEV_SIGNAL;
528 new_timer->sigq.info.si_signo = SIGALRM;
529 new_timer->sigq.info.si_value.sival_int = new_timer->it_id;
530 new_timer->it_pid = get_pid(task_tgid(current));
531 }
532
533 if (new_timer->it_sigev_notify & SIGEV_THREAD_ID)
534 new_timer->it_pid_type = PIDTYPE_PID;
535 else
536 new_timer->it_pid_type = PIDTYPE_TGID;
537
538 new_timer->sigq.info.si_tid = new_timer->it_id;
539 new_timer->sigq.info.si_code = SI_TIMER;
540
541 if (copy_to_user(created_timer_id, &new_timer_id, sizeof (new_timer_id))) {
542 error = -EFAULT;
543 goto out;
544 }
545 /*
546 * After succesful copy out, the timer ID is visible to user space
547 * now but not yet valid because new_timer::signal low order bit is 1.
548 *
549 * Complete the initialization with the clock specific create
550 * callback.
551 */
552 error = kc->timer_create(new_timer);
553 if (error)
554 goto out;
555
556 /*
557 * timer::it_lock ensures that __lock_timer() observes a fully
558 * initialized timer when it observes a valid timer::it_signal.
559 *
560 * sighand::siglock is required to protect signal::posix_timers.
561 */
562 scoped_guard (spinlock_irq, &new_timer->it_lock) {
563 guard(spinlock)(¤t->sighand->siglock);
564 /*
565 * new_timer::it_signal contains the signal pointer with
566 * bit 0 set, which makes it invalid for syscall operations.
567 * Store the unmodified signal pointer to make it valid.
568 */
569 WRITE_ONCE(new_timer->it_signal, current->signal);
570 hlist_add_head_rcu(&new_timer->list, ¤t->signal->posix_timers);
571 }
572 /*
573 * After unlocking @new_timer is subject to concurrent removal and
574 * cannot be touched anymore
575 */
576 return 0;
577 out:
578 posix_timer_unhash_and_free(new_timer);
579 return error;
580 }
581
SYSCALL_DEFINE3(timer_create,const clockid_t,which_clock,struct sigevent __user *,timer_event_spec,timer_t __user *,created_timer_id)582 SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
583 struct sigevent __user *, timer_event_spec,
584 timer_t __user *, created_timer_id)
585 {
586 if (timer_event_spec) {
587 sigevent_t event;
588
589 if (copy_from_user(&event, timer_event_spec, sizeof (event)))
590 return -EFAULT;
591 return do_timer_create(which_clock, &event, created_timer_id);
592 }
593 return do_timer_create(which_clock, NULL, created_timer_id);
594 }
595
596 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(timer_create,clockid_t,which_clock,struct compat_sigevent __user *,timer_event_spec,timer_t __user *,created_timer_id)597 COMPAT_SYSCALL_DEFINE3(timer_create, clockid_t, which_clock,
598 struct compat_sigevent __user *, timer_event_spec,
599 timer_t __user *, created_timer_id)
600 {
601 if (timer_event_spec) {
602 sigevent_t event;
603
604 if (get_compat_sigevent(&event, timer_event_spec))
605 return -EFAULT;
606 return do_timer_create(which_clock, &event, created_timer_id);
607 }
608 return do_timer_create(which_clock, NULL, created_timer_id);
609 }
610 #endif
611
__lock_timer(timer_t timer_id)612 static struct k_itimer *__lock_timer(timer_t timer_id)
613 {
614 struct k_itimer *timr;
615
616 /*
617 * timer_t could be any type >= int and we want to make sure any
618 * @timer_id outside positive int range fails lookup.
619 */
620 if ((unsigned long long)timer_id > INT_MAX)
621 return NULL;
622
623 /*
624 * The hash lookup and the timers are RCU protected.
625 *
626 * Timers are added to the hash in invalid state where
627 * timr::it_signal is marked invalid. timer::it_signal is only set
628 * after the rest of the initialization succeeded.
629 *
630 * Timer destruction happens in steps:
631 * 1) Set timr::it_signal marked invalid with timr::it_lock held
632 * 2) Release timr::it_lock
633 * 3) Remove from the hash under hash_lock
634 * 4) Put the reference count.
635 *
636 * The reference count might not drop to zero if timr::sigq is
637 * queued. In that case the signal delivery or flush will put the
638 * last reference count.
639 *
640 * When the reference count reaches zero, the timer is scheduled
641 * for RCU removal after the grace period.
642 *
643 * Holding rcu_read_lock() across the lookup ensures that
644 * the timer cannot be freed.
645 *
646 * The lookup validates locklessly that timr::it_signal ==
647 * current::it_signal and timr::it_id == @timer_id. timr::it_id
648 * can't change, but timr::it_signal can become invalid during
649 * destruction, which makes the locked check fail.
650 */
651 guard(rcu)();
652 timr = posix_timer_by_id(timer_id);
653 if (timr) {
654 spin_lock_irq(&timr->it_lock);
655 /*
656 * Validate under timr::it_lock that timr::it_signal is
657 * still valid. Pairs with #1 above.
658 */
659 if (timr->it_signal == current->signal)
660 return timr;
661 spin_unlock_irq(&timr->it_lock);
662 }
663 return NULL;
664 }
665
common_hrtimer_remaining(struct k_itimer * timr,ktime_t now)666 static ktime_t common_hrtimer_remaining(struct k_itimer *timr, ktime_t now)
667 {
668 struct hrtimer *timer = &timr->it.real.timer;
669
670 return __hrtimer_expires_remaining_adjusted(timer, now);
671 }
672
common_hrtimer_forward(struct k_itimer * timr,ktime_t now)673 static s64 common_hrtimer_forward(struct k_itimer *timr, ktime_t now)
674 {
675 struct hrtimer *timer = &timr->it.real.timer;
676
677 return hrtimer_forward(timer, now, timr->it_interval);
678 }
679
680 /*
681 * Get the time remaining on a POSIX.1b interval timer.
682 *
683 * Two issues to handle here:
684 *
685 * 1) The timer has a requeue pending. The return value must appear as
686 * if the timer has been requeued right now.
687 *
688 * 2) The timer is a SIGEV_NONE timer. These timers are never enqueued
689 * into the hrtimer queue and therefore never expired. Emulate expiry
690 * here taking #1 into account.
691 */
common_timer_get(struct k_itimer * timr,struct itimerspec64 * cur_setting)692 void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
693 {
694 const struct k_clock *kc = timr->kclock;
695 ktime_t now, remaining, iv;
696 bool sig_none;
697
698 sig_none = timr->it_sigev_notify == SIGEV_NONE;
699 iv = timr->it_interval;
700
701 /* interval timer ? */
702 if (iv) {
703 cur_setting->it_interval = ktime_to_timespec64(iv);
704 } else if (timr->it_status == POSIX_TIMER_DISARMED) {
705 /*
706 * SIGEV_NONE oneshot timers are never queued and therefore
707 * timr->it_status is always DISARMED. The check below
708 * vs. remaining time will handle this case.
709 *
710 * For all other timers there is nothing to update here, so
711 * return.
712 */
713 if (!sig_none)
714 return;
715 }
716
717 now = kc->clock_get_ktime(timr->it_clock);
718
719 /*
720 * If this is an interval timer and either has requeue pending or
721 * is a SIGEV_NONE timer move the expiry time forward by intervals,
722 * so expiry is > now.
723 */
724 if (iv && timr->it_status != POSIX_TIMER_ARMED)
725 timr->it_overrun += kc->timer_forward(timr, now);
726
727 remaining = kc->timer_remaining(timr, now);
728 /*
729 * As @now is retrieved before a possible timer_forward() and
730 * cannot be reevaluated by the compiler @remaining is based on the
731 * same @now value. Therefore @remaining is consistent vs. @now.
732 *
733 * Consequently all interval timers, i.e. @iv > 0, cannot have a
734 * remaining time <= 0 because timer_forward() guarantees to move
735 * them forward so that the next timer expiry is > @now.
736 */
737 if (remaining <= 0) {
738 /*
739 * A single shot SIGEV_NONE timer must return 0, when it is
740 * expired! Timers which have a real signal delivery mode
741 * must return a remaining time greater than 0 because the
742 * signal has not yet been delivered.
743 */
744 if (!sig_none)
745 cur_setting->it_value.tv_nsec = 1;
746 } else {
747 cur_setting->it_value = ktime_to_timespec64(remaining);
748 }
749 }
750
do_timer_gettime(timer_t timer_id,struct itimerspec64 * setting)751 static int do_timer_gettime(timer_t timer_id, struct itimerspec64 *setting)
752 {
753 memset(setting, 0, sizeof(*setting));
754 scoped_timer_get_or_fail(timer_id)
755 scoped_timer->kclock->timer_get(scoped_timer, setting);
756 return 0;
757 }
758
759 /* Get the time remaining on a POSIX.1b interval timer. */
SYSCALL_DEFINE2(timer_gettime,timer_t,timer_id,struct __kernel_itimerspec __user *,setting)760 SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
761 struct __kernel_itimerspec __user *, setting)
762 {
763 struct itimerspec64 cur_setting;
764
765 int ret = do_timer_gettime(timer_id, &cur_setting);
766 if (!ret) {
767 if (put_itimerspec64(&cur_setting, setting))
768 ret = -EFAULT;
769 }
770 return ret;
771 }
772
773 #ifdef CONFIG_COMPAT_32BIT_TIME
774
SYSCALL_DEFINE2(timer_gettime32,timer_t,timer_id,struct old_itimerspec32 __user *,setting)775 SYSCALL_DEFINE2(timer_gettime32, timer_t, timer_id,
776 struct old_itimerspec32 __user *, setting)
777 {
778 struct itimerspec64 cur_setting;
779
780 int ret = do_timer_gettime(timer_id, &cur_setting);
781 if (!ret) {
782 if (put_old_itimerspec32(&cur_setting, setting))
783 ret = -EFAULT;
784 }
785 return ret;
786 }
787
788 #endif
789
790 /**
791 * sys_timer_getoverrun - Get the number of overruns of a POSIX.1b interval timer
792 * @timer_id: The timer ID which identifies the timer
793 *
794 * The "overrun count" of a timer is one plus the number of expiration
795 * intervals which have elapsed between the first expiry, which queues the
796 * signal and the actual signal delivery. On signal delivery the "overrun
797 * count" is calculated and cached, so it can be returned directly here.
798 *
799 * As this is relative to the last queued signal the returned overrun count
800 * is meaningless outside of the signal delivery path and even there it
801 * does not accurately reflect the current state when user space evaluates
802 * it.
803 *
804 * Returns:
805 * -EINVAL @timer_id is invalid
806 * 1..INT_MAX The number of overruns related to the last delivered signal
807 */
SYSCALL_DEFINE1(timer_getoverrun,timer_t,timer_id)808 SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
809 {
810 scoped_timer_get_or_fail(timer_id)
811 return timer_overrun_to_int(scoped_timer);
812 }
813
common_hrtimer_arm(struct k_itimer * timr,ktime_t expires,bool absolute,bool sigev_none)814 static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
815 bool absolute, bool sigev_none)
816 {
817 struct hrtimer *timer = &timr->it.real.timer;
818 enum hrtimer_mode mode;
819
820 mode = absolute ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
821 /*
822 * Posix magic: Relative CLOCK_REALTIME timers are not affected by
823 * clock modifications, so they become CLOCK_MONOTONIC based under the
824 * hood. See hrtimer_setup(). Update timr->kclock, so the generic
825 * functions which use timr->kclock->clock_get_*() work.
826 *
827 * Note: it_clock stays unmodified, because the next timer_set() might
828 * use ABSTIME, so it needs to switch back.
829 */
830 if (timr->it_clock == CLOCK_REALTIME)
831 timr->kclock = absolute ? &clock_realtime : &clock_monotonic;
832
833 hrtimer_setup(&timr->it.real.timer, posix_timer_fn, timr->it_clock, mode);
834
835 if (!absolute)
836 expires = ktime_add_safe(expires, timer->base->get_time());
837 hrtimer_set_expires(timer, expires);
838
839 if (!sigev_none)
840 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
841 }
842
common_hrtimer_try_to_cancel(struct k_itimer * timr)843 static int common_hrtimer_try_to_cancel(struct k_itimer *timr)
844 {
845 return hrtimer_try_to_cancel(&timr->it.real.timer);
846 }
847
common_timer_wait_running(struct k_itimer * timer)848 static void common_timer_wait_running(struct k_itimer *timer)
849 {
850 hrtimer_cancel_wait_running(&timer->it.real.timer);
851 }
852
853 /*
854 * On PREEMPT_RT this prevents priority inversion and a potential livelock
855 * against the ksoftirqd thread in case that ksoftirqd gets preempted while
856 * executing a hrtimer callback.
857 *
858 * See the comments in hrtimer_cancel_wait_running(). For PREEMPT_RT=n this
859 * just results in a cpu_relax().
860 *
861 * For POSIX CPU timers with CONFIG_POSIX_CPU_TIMERS_TASK_WORK=n this is
862 * just a cpu_relax(). With CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y this
863 * prevents spinning on an eventually scheduled out task and a livelock
864 * when the task which tries to delete or disarm the timer has preempted
865 * the task which runs the expiry in task work context.
866 */
timer_wait_running(struct k_itimer * timer)867 static void timer_wait_running(struct k_itimer *timer)
868 {
869 /*
870 * kc->timer_wait_running() might drop RCU lock. So @timer
871 * cannot be touched anymore after the function returns!
872 */
873 timer->kclock->timer_wait_running(timer);
874 }
875
876 /*
877 * Set up the new interval and reset the signal delivery data
878 */
posix_timer_set_common(struct k_itimer * timer,struct itimerspec64 * new_setting)879 void posix_timer_set_common(struct k_itimer *timer, struct itimerspec64 *new_setting)
880 {
881 if (new_setting->it_value.tv_sec || new_setting->it_value.tv_nsec)
882 timer->it_interval = timespec64_to_ktime(new_setting->it_interval);
883 else
884 timer->it_interval = 0;
885
886 /* Reset overrun accounting */
887 timer->it_overrun_last = 0;
888 timer->it_overrun = -1LL;
889 }
890
891 /* Set a POSIX.1b interval timer. */
common_timer_set(struct k_itimer * timr,int flags,struct itimerspec64 * new_setting,struct itimerspec64 * old_setting)892 int common_timer_set(struct k_itimer *timr, int flags,
893 struct itimerspec64 *new_setting,
894 struct itimerspec64 *old_setting)
895 {
896 const struct k_clock *kc = timr->kclock;
897 bool sigev_none;
898 ktime_t expires;
899
900 if (old_setting)
901 common_timer_get(timr, old_setting);
902
903 /*
904 * Careful here. On SMP systems the timer expiry function could be
905 * active and spinning on timr->it_lock.
906 */
907 if (kc->timer_try_to_cancel(timr) < 0)
908 return TIMER_RETRY;
909
910 timr->it_status = POSIX_TIMER_DISARMED;
911 posix_timer_set_common(timr, new_setting);
912
913 /* Keep timer disarmed when it_value is zero */
914 if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
915 return 0;
916
917 expires = timespec64_to_ktime(new_setting->it_value);
918 if (flags & TIMER_ABSTIME)
919 expires = timens_ktime_to_host(timr->it_clock, expires);
920 sigev_none = timr->it_sigev_notify == SIGEV_NONE;
921
922 kc->timer_arm(timr, expires, flags & TIMER_ABSTIME, sigev_none);
923 if (!sigev_none)
924 timr->it_status = POSIX_TIMER_ARMED;
925 return 0;
926 }
927
do_timer_settime(timer_t timer_id,int tmr_flags,struct itimerspec64 * new_spec64,struct itimerspec64 * old_spec64)928 static int do_timer_settime(timer_t timer_id, int tmr_flags, struct itimerspec64 *new_spec64,
929 struct itimerspec64 *old_spec64)
930 {
931 if (!timespec64_valid(&new_spec64->it_interval) ||
932 !timespec64_valid(&new_spec64->it_value))
933 return -EINVAL;
934
935 if (old_spec64)
936 memset(old_spec64, 0, sizeof(*old_spec64));
937
938 for (; ; old_spec64 = NULL) {
939 struct k_itimer *timr;
940
941 scoped_timer_get_or_fail(timer_id) {
942 timr = scoped_timer;
943
944 if (old_spec64)
945 old_spec64->it_interval = ktime_to_timespec64(timr->it_interval);
946
947 /* Prevent signal delivery and rearming. */
948 timr->it_signal_seq++;
949
950 int ret = timr->kclock->timer_set(timr, tmr_flags, new_spec64, old_spec64);
951 if (ret != TIMER_RETRY)
952 return ret;
953
954 /* Protect the timer from being freed when leaving the lock scope */
955 rcu_read_lock();
956 }
957 timer_wait_running(timr);
958 rcu_read_unlock();
959 }
960 }
961
962 /* Set a POSIX.1b interval timer */
SYSCALL_DEFINE4(timer_settime,timer_t,timer_id,int,flags,const struct __kernel_itimerspec __user *,new_setting,struct __kernel_itimerspec __user *,old_setting)963 SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
964 const struct __kernel_itimerspec __user *, new_setting,
965 struct __kernel_itimerspec __user *, old_setting)
966 {
967 struct itimerspec64 new_spec, old_spec, *rtn;
968 int error = 0;
969
970 if (!new_setting)
971 return -EINVAL;
972
973 if (get_itimerspec64(&new_spec, new_setting))
974 return -EFAULT;
975
976 rtn = old_setting ? &old_spec : NULL;
977 error = do_timer_settime(timer_id, flags, &new_spec, rtn);
978 if (!error && old_setting) {
979 if (put_itimerspec64(&old_spec, old_setting))
980 error = -EFAULT;
981 }
982 return error;
983 }
984
985 #ifdef CONFIG_COMPAT_32BIT_TIME
SYSCALL_DEFINE4(timer_settime32,timer_t,timer_id,int,flags,struct old_itimerspec32 __user *,new,struct old_itimerspec32 __user *,old)986 SYSCALL_DEFINE4(timer_settime32, timer_t, timer_id, int, flags,
987 struct old_itimerspec32 __user *, new,
988 struct old_itimerspec32 __user *, old)
989 {
990 struct itimerspec64 new_spec, old_spec;
991 struct itimerspec64 *rtn = old ? &old_spec : NULL;
992 int error = 0;
993
994 if (!new)
995 return -EINVAL;
996 if (get_old_itimerspec32(&new_spec, new))
997 return -EFAULT;
998
999 error = do_timer_settime(timer_id, flags, &new_spec, rtn);
1000 if (!error && old) {
1001 if (put_old_itimerspec32(&old_spec, old))
1002 error = -EFAULT;
1003 }
1004 return error;
1005 }
1006 #endif
1007
common_timer_del(struct k_itimer * timer)1008 int common_timer_del(struct k_itimer *timer)
1009 {
1010 const struct k_clock *kc = timer->kclock;
1011
1012 if (kc->timer_try_to_cancel(timer) < 0)
1013 return TIMER_RETRY;
1014 timer->it_status = POSIX_TIMER_DISARMED;
1015 return 0;
1016 }
1017
1018 /*
1019 * If the deleted timer is on the ignored list, remove it and
1020 * drop the associated reference.
1021 */
posix_timer_cleanup_ignored(struct k_itimer * tmr)1022 static inline void posix_timer_cleanup_ignored(struct k_itimer *tmr)
1023 {
1024 if (!hlist_unhashed(&tmr->ignored_list)) {
1025 hlist_del_init(&tmr->ignored_list);
1026 posixtimer_putref(tmr);
1027 }
1028 }
1029
posix_timer_delete(struct k_itimer * timer)1030 static void posix_timer_delete(struct k_itimer *timer)
1031 {
1032 /*
1033 * Invalidate the timer, remove it from the linked list and remove
1034 * it from the ignored list if pending.
1035 *
1036 * The invalidation must be written with siglock held so that the
1037 * signal code observes the invalidated timer::it_signal in
1038 * do_sigaction(), which prevents it from moving a pending signal
1039 * of a deleted timer to the ignore list.
1040 *
1041 * The invalidation also prevents signal queueing, signal delivery
1042 * and therefore rearming from the signal delivery path.
1043 *
1044 * A concurrent lookup can still find the timer in the hash, but it
1045 * will check timer::it_signal with timer::it_lock held and observe
1046 * bit 0 set, which invalidates it. That also prevents the timer ID
1047 * from being handed out before this timer is completely gone.
1048 */
1049 timer->it_signal_seq++;
1050
1051 scoped_guard (spinlock, ¤t->sighand->siglock) {
1052 unsigned long sig = (unsigned long)timer->it_signal | 1UL;
1053
1054 WRITE_ONCE(timer->it_signal, (struct signal_struct *)sig);
1055 hlist_del_rcu(&timer->list);
1056 posix_timer_cleanup_ignored(timer);
1057 }
1058
1059 while (timer->kclock->timer_del(timer) == TIMER_RETRY) {
1060 guard(rcu)();
1061 spin_unlock_irq(&timer->it_lock);
1062 timer_wait_running(timer);
1063 spin_lock_irq(&timer->it_lock);
1064 }
1065 }
1066
1067 /* Delete a POSIX.1b interval timer. */
SYSCALL_DEFINE1(timer_delete,timer_t,timer_id)1068 SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
1069 {
1070 struct k_itimer *timer;
1071
1072 scoped_timer_get_or_fail(timer_id) {
1073 timer = scoped_timer;
1074 posix_timer_delete(timer);
1075 }
1076 /* Remove it from the hash, which frees up the timer ID */
1077 posix_timer_unhash_and_free(timer);
1078 return 0;
1079 }
1080
1081 /*
1082 * Invoked from do_exit() when the last thread of a thread group exits.
1083 * At that point no other task can access the timers of the dying
1084 * task anymore.
1085 */
exit_itimers(struct task_struct * tsk)1086 void exit_itimers(struct task_struct *tsk)
1087 {
1088 struct hlist_head timers;
1089 struct hlist_node *next;
1090 struct k_itimer *timer;
1091
1092 /* Clear restore mode for exec() */
1093 tsk->signal->timer_create_restore_ids = 0;
1094
1095 if (hlist_empty(&tsk->signal->posix_timers))
1096 return;
1097
1098 /* Protect against concurrent read via /proc/$PID/timers */
1099 scoped_guard (spinlock_irq, &tsk->sighand->siglock)
1100 hlist_move_list(&tsk->signal->posix_timers, &timers);
1101
1102 /* The timers are not longer accessible via tsk::signal */
1103 hlist_for_each_entry_safe(timer, next, &timers, list) {
1104 scoped_guard (spinlock_irq, &timer->it_lock)
1105 posix_timer_delete(timer);
1106 posix_timer_unhash_and_free(timer);
1107 cond_resched();
1108 }
1109
1110 /*
1111 * There should be no timers on the ignored list. itimer_delete() has
1112 * mopped them up.
1113 */
1114 if (!WARN_ON_ONCE(!hlist_empty(&tsk->signal->ignored_posix_timers)))
1115 return;
1116
1117 hlist_move_list(&tsk->signal->ignored_posix_timers, &timers);
1118 while (!hlist_empty(&timers)) {
1119 posix_timer_cleanup_ignored(hlist_entry(timers.first, struct k_itimer,
1120 ignored_list));
1121 }
1122 }
1123
SYSCALL_DEFINE2(clock_settime,const clockid_t,which_clock,const struct __kernel_timespec __user *,tp)1124 SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
1125 const struct __kernel_timespec __user *, tp)
1126 {
1127 const struct k_clock *kc = clockid_to_kclock(which_clock);
1128 struct timespec64 new_tp;
1129
1130 if (!kc || !kc->clock_set)
1131 return -EINVAL;
1132
1133 if (get_timespec64(&new_tp, tp))
1134 return -EFAULT;
1135
1136 /*
1137 * Permission checks have to be done inside the clock specific
1138 * setter callback.
1139 */
1140 return kc->clock_set(which_clock, &new_tp);
1141 }
1142
SYSCALL_DEFINE2(clock_gettime,const clockid_t,which_clock,struct __kernel_timespec __user *,tp)1143 SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
1144 struct __kernel_timespec __user *, tp)
1145 {
1146 const struct k_clock *kc = clockid_to_kclock(which_clock);
1147 struct timespec64 kernel_tp;
1148 int error;
1149
1150 if (!kc)
1151 return -EINVAL;
1152
1153 error = kc->clock_get_timespec(which_clock, &kernel_tp);
1154
1155 if (!error && put_timespec64(&kernel_tp, tp))
1156 error = -EFAULT;
1157
1158 return error;
1159 }
1160
do_clock_adjtime(const clockid_t which_clock,struct __kernel_timex * ktx)1161 int do_clock_adjtime(const clockid_t which_clock, struct __kernel_timex * ktx)
1162 {
1163 const struct k_clock *kc = clockid_to_kclock(which_clock);
1164
1165 if (!kc)
1166 return -EINVAL;
1167 if (!kc->clock_adj)
1168 return -EOPNOTSUPP;
1169
1170 return kc->clock_adj(which_clock, ktx);
1171 }
1172
SYSCALL_DEFINE2(clock_adjtime,const clockid_t,which_clock,struct __kernel_timex __user *,utx)1173 SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
1174 struct __kernel_timex __user *, utx)
1175 {
1176 struct __kernel_timex ktx;
1177 int err;
1178
1179 if (copy_from_user(&ktx, utx, sizeof(ktx)))
1180 return -EFAULT;
1181
1182 err = do_clock_adjtime(which_clock, &ktx);
1183
1184 if (err >= 0 && copy_to_user(utx, &ktx, sizeof(ktx)))
1185 return -EFAULT;
1186
1187 return err;
1188 }
1189
1190 /**
1191 * sys_clock_getres - Get the resolution of a clock
1192 * @which_clock: The clock to get the resolution for
1193 * @tp: Pointer to a a user space timespec64 for storage
1194 *
1195 * POSIX defines:
1196 *
1197 * "The clock_getres() function shall return the resolution of any
1198 * clock. Clock resolutions are implementation-defined and cannot be set by
1199 * a process. If the argument res is not NULL, the resolution of the
1200 * specified clock shall be stored in the location pointed to by res. If
1201 * res is NULL, the clock resolution is not returned. If the time argument
1202 * of clock_settime() is not a multiple of res, then the value is truncated
1203 * to a multiple of res."
1204 *
1205 * Due to the various hardware constraints the real resolution can vary
1206 * wildly and even change during runtime when the underlying devices are
1207 * replaced. The kernel also can use hardware devices with different
1208 * resolutions for reading the time and for arming timers.
1209 *
1210 * The kernel therefore deviates from the POSIX spec in various aspects:
1211 *
1212 * 1) The resolution returned to user space
1213 *
1214 * For CLOCK_REALTIME, CLOCK_MONOTONIC, CLOCK_BOOTTIME, CLOCK_TAI,
1215 * CLOCK_REALTIME_ALARM, CLOCK_BOOTTIME_ALAREM and CLOCK_MONOTONIC_RAW
1216 * the kernel differentiates only two cases:
1217 *
1218 * I) Low resolution mode:
1219 *
1220 * When high resolution timers are disabled at compile or runtime
1221 * the resolution returned is nanoseconds per tick, which represents
1222 * the precision at which timers expire.
1223 *
1224 * II) High resolution mode:
1225 *
1226 * When high resolution timers are enabled the resolution returned
1227 * is always one nanosecond independent of the actual resolution of
1228 * the underlying hardware devices.
1229 *
1230 * For CLOCK_*_ALARM the actual resolution depends on system
1231 * state. When system is running the resolution is the same as the
1232 * resolution of the other clocks. During suspend the actual
1233 * resolution is the resolution of the underlying RTC device which
1234 * might be way less precise than the clockevent device used during
1235 * running state.
1236 *
1237 * For CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE the resolution
1238 * returned is always nanoseconds per tick.
1239 *
1240 * For CLOCK_PROCESS_CPUTIME and CLOCK_THREAD_CPUTIME the resolution
1241 * returned is always one nanosecond under the assumption that the
1242 * underlying scheduler clock has a better resolution than nanoseconds
1243 * per tick.
1244 *
1245 * For dynamic POSIX clocks (PTP devices) the resolution returned is
1246 * always one nanosecond.
1247 *
1248 * 2) Affect on sys_clock_settime()
1249 *
1250 * The kernel does not truncate the time which is handed in to
1251 * sys_clock_settime(). The kernel internal timekeeping is always using
1252 * nanoseconds precision independent of the clocksource device which is
1253 * used to read the time from. The resolution of that device only
1254 * affects the presicion of the time returned by sys_clock_gettime().
1255 *
1256 * Returns:
1257 * 0 Success. @tp contains the resolution
1258 * -EINVAL @which_clock is not a valid clock ID
1259 * -EFAULT Copying the resolution to @tp faulted
1260 * -ENODEV Dynamic POSIX clock is not backed by a device
1261 * -EOPNOTSUPP Dynamic POSIX clock does not support getres()
1262 */
SYSCALL_DEFINE2(clock_getres,const clockid_t,which_clock,struct __kernel_timespec __user *,tp)1263 SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
1264 struct __kernel_timespec __user *, tp)
1265 {
1266 const struct k_clock *kc = clockid_to_kclock(which_clock);
1267 struct timespec64 rtn_tp;
1268 int error;
1269
1270 if (!kc)
1271 return -EINVAL;
1272
1273 error = kc->clock_getres(which_clock, &rtn_tp);
1274
1275 if (!error && tp && put_timespec64(&rtn_tp, tp))
1276 error = -EFAULT;
1277
1278 return error;
1279 }
1280
1281 #ifdef CONFIG_COMPAT_32BIT_TIME
1282
SYSCALL_DEFINE2(clock_settime32,clockid_t,which_clock,struct old_timespec32 __user *,tp)1283 SYSCALL_DEFINE2(clock_settime32, clockid_t, which_clock,
1284 struct old_timespec32 __user *, tp)
1285 {
1286 const struct k_clock *kc = clockid_to_kclock(which_clock);
1287 struct timespec64 ts;
1288
1289 if (!kc || !kc->clock_set)
1290 return -EINVAL;
1291
1292 if (get_old_timespec32(&ts, tp))
1293 return -EFAULT;
1294
1295 return kc->clock_set(which_clock, &ts);
1296 }
1297
SYSCALL_DEFINE2(clock_gettime32,clockid_t,which_clock,struct old_timespec32 __user *,tp)1298 SYSCALL_DEFINE2(clock_gettime32, clockid_t, which_clock,
1299 struct old_timespec32 __user *, tp)
1300 {
1301 const struct k_clock *kc = clockid_to_kclock(which_clock);
1302 struct timespec64 ts;
1303 int err;
1304
1305 if (!kc)
1306 return -EINVAL;
1307
1308 err = kc->clock_get_timespec(which_clock, &ts);
1309
1310 if (!err && put_old_timespec32(&ts, tp))
1311 err = -EFAULT;
1312
1313 return err;
1314 }
1315
SYSCALL_DEFINE2(clock_adjtime32,clockid_t,which_clock,struct old_timex32 __user *,utp)1316 SYSCALL_DEFINE2(clock_adjtime32, clockid_t, which_clock,
1317 struct old_timex32 __user *, utp)
1318 {
1319 struct __kernel_timex ktx;
1320 int err;
1321
1322 err = get_old_timex32(&ktx, utp);
1323 if (err)
1324 return err;
1325
1326 err = do_clock_adjtime(which_clock, &ktx);
1327
1328 if (err >= 0 && put_old_timex32(utp, &ktx))
1329 return -EFAULT;
1330
1331 return err;
1332 }
1333
SYSCALL_DEFINE2(clock_getres_time32,clockid_t,which_clock,struct old_timespec32 __user *,tp)1334 SYSCALL_DEFINE2(clock_getres_time32, clockid_t, which_clock,
1335 struct old_timespec32 __user *, tp)
1336 {
1337 const struct k_clock *kc = clockid_to_kclock(which_clock);
1338 struct timespec64 ts;
1339 int err;
1340
1341 if (!kc)
1342 return -EINVAL;
1343
1344 err = kc->clock_getres(which_clock, &ts);
1345 if (!err && tp && put_old_timespec32(&ts, tp))
1346 return -EFAULT;
1347
1348 return err;
1349 }
1350
1351 #endif
1352
1353 /*
1354 * sys_clock_nanosleep() for CLOCK_REALTIME and CLOCK_TAI
1355 */
common_nsleep(const clockid_t which_clock,int flags,const struct timespec64 * rqtp)1356 static int common_nsleep(const clockid_t which_clock, int flags,
1357 const struct timespec64 *rqtp)
1358 {
1359 ktime_t texp = timespec64_to_ktime(*rqtp);
1360
1361 return hrtimer_nanosleep(texp, flags & TIMER_ABSTIME ?
1362 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
1363 which_clock);
1364 }
1365
1366 /*
1367 * sys_clock_nanosleep() for CLOCK_MONOTONIC and CLOCK_BOOTTIME
1368 *
1369 * Absolute nanosleeps for these clocks are time-namespace adjusted.
1370 */
common_nsleep_timens(const clockid_t which_clock,int flags,const struct timespec64 * rqtp)1371 static int common_nsleep_timens(const clockid_t which_clock, int flags,
1372 const struct timespec64 *rqtp)
1373 {
1374 ktime_t texp = timespec64_to_ktime(*rqtp);
1375
1376 if (flags & TIMER_ABSTIME)
1377 texp = timens_ktime_to_host(which_clock, texp);
1378
1379 return hrtimer_nanosleep(texp, flags & TIMER_ABSTIME ?
1380 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
1381 which_clock);
1382 }
1383
SYSCALL_DEFINE4(clock_nanosleep,const clockid_t,which_clock,int,flags,const struct __kernel_timespec __user *,rqtp,struct __kernel_timespec __user *,rmtp)1384 SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
1385 const struct __kernel_timespec __user *, rqtp,
1386 struct __kernel_timespec __user *, rmtp)
1387 {
1388 const struct k_clock *kc = clockid_to_kclock(which_clock);
1389 struct timespec64 t;
1390
1391 if (!kc)
1392 return -EINVAL;
1393 if (!kc->nsleep)
1394 return -EOPNOTSUPP;
1395
1396 if (get_timespec64(&t, rqtp))
1397 return -EFAULT;
1398
1399 if (!timespec64_valid(&t))
1400 return -EINVAL;
1401 if (flags & TIMER_ABSTIME)
1402 rmtp = NULL;
1403 current->restart_block.fn = do_no_restart_syscall;
1404 current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
1405 current->restart_block.nanosleep.rmtp = rmtp;
1406
1407 return kc->nsleep(which_clock, flags, &t);
1408 }
1409
1410 #ifdef CONFIG_COMPAT_32BIT_TIME
1411
SYSCALL_DEFINE4(clock_nanosleep_time32,clockid_t,which_clock,int,flags,struct old_timespec32 __user *,rqtp,struct old_timespec32 __user *,rmtp)1412 SYSCALL_DEFINE4(clock_nanosleep_time32, clockid_t, which_clock, int, flags,
1413 struct old_timespec32 __user *, rqtp,
1414 struct old_timespec32 __user *, rmtp)
1415 {
1416 const struct k_clock *kc = clockid_to_kclock(which_clock);
1417 struct timespec64 t;
1418
1419 if (!kc)
1420 return -EINVAL;
1421 if (!kc->nsleep)
1422 return -EOPNOTSUPP;
1423
1424 if (get_old_timespec32(&t, rqtp))
1425 return -EFAULT;
1426
1427 if (!timespec64_valid(&t))
1428 return -EINVAL;
1429 if (flags & TIMER_ABSTIME)
1430 rmtp = NULL;
1431 current->restart_block.fn = do_no_restart_syscall;
1432 current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
1433 current->restart_block.nanosleep.compat_rmtp = rmtp;
1434
1435 return kc->nsleep(which_clock, flags, &t);
1436 }
1437
1438 #endif
1439
1440 static const struct k_clock clock_realtime = {
1441 .clock_getres = posix_get_hrtimer_res,
1442 .clock_get_timespec = posix_get_realtime_timespec,
1443 .clock_get_ktime = posix_get_realtime_ktime,
1444 .clock_set = posix_clock_realtime_set,
1445 .clock_adj = posix_clock_realtime_adj,
1446 .nsleep = common_nsleep,
1447 .timer_create = common_timer_create,
1448 .timer_set = common_timer_set,
1449 .timer_get = common_timer_get,
1450 .timer_del = common_timer_del,
1451 .timer_rearm = common_hrtimer_rearm,
1452 .timer_forward = common_hrtimer_forward,
1453 .timer_remaining = common_hrtimer_remaining,
1454 .timer_try_to_cancel = common_hrtimer_try_to_cancel,
1455 .timer_wait_running = common_timer_wait_running,
1456 .timer_arm = common_hrtimer_arm,
1457 };
1458
1459 static const struct k_clock clock_monotonic = {
1460 .clock_getres = posix_get_hrtimer_res,
1461 .clock_get_timespec = posix_get_monotonic_timespec,
1462 .clock_get_ktime = posix_get_monotonic_ktime,
1463 .nsleep = common_nsleep_timens,
1464 .timer_create = common_timer_create,
1465 .timer_set = common_timer_set,
1466 .timer_get = common_timer_get,
1467 .timer_del = common_timer_del,
1468 .timer_rearm = common_hrtimer_rearm,
1469 .timer_forward = common_hrtimer_forward,
1470 .timer_remaining = common_hrtimer_remaining,
1471 .timer_try_to_cancel = common_hrtimer_try_to_cancel,
1472 .timer_wait_running = common_timer_wait_running,
1473 .timer_arm = common_hrtimer_arm,
1474 };
1475
1476 static const struct k_clock clock_monotonic_raw = {
1477 .clock_getres = posix_get_hrtimer_res,
1478 .clock_get_timespec = posix_get_monotonic_raw,
1479 };
1480
1481 static const struct k_clock clock_realtime_coarse = {
1482 .clock_getres = posix_get_coarse_res,
1483 .clock_get_timespec = posix_get_realtime_coarse,
1484 };
1485
1486 static const struct k_clock clock_monotonic_coarse = {
1487 .clock_getres = posix_get_coarse_res,
1488 .clock_get_timespec = posix_get_monotonic_coarse,
1489 };
1490
1491 static const struct k_clock clock_tai = {
1492 .clock_getres = posix_get_hrtimer_res,
1493 .clock_get_ktime = posix_get_tai_ktime,
1494 .clock_get_timespec = posix_get_tai_timespec,
1495 .nsleep = common_nsleep,
1496 .timer_create = common_timer_create,
1497 .timer_set = common_timer_set,
1498 .timer_get = common_timer_get,
1499 .timer_del = common_timer_del,
1500 .timer_rearm = common_hrtimer_rearm,
1501 .timer_forward = common_hrtimer_forward,
1502 .timer_remaining = common_hrtimer_remaining,
1503 .timer_try_to_cancel = common_hrtimer_try_to_cancel,
1504 .timer_wait_running = common_timer_wait_running,
1505 .timer_arm = common_hrtimer_arm,
1506 };
1507
1508 static const struct k_clock clock_boottime = {
1509 .clock_getres = posix_get_hrtimer_res,
1510 .clock_get_ktime = posix_get_boottime_ktime,
1511 .clock_get_timespec = posix_get_boottime_timespec,
1512 .nsleep = common_nsleep_timens,
1513 .timer_create = common_timer_create,
1514 .timer_set = common_timer_set,
1515 .timer_get = common_timer_get,
1516 .timer_del = common_timer_del,
1517 .timer_rearm = common_hrtimer_rearm,
1518 .timer_forward = common_hrtimer_forward,
1519 .timer_remaining = common_hrtimer_remaining,
1520 .timer_try_to_cancel = common_hrtimer_try_to_cancel,
1521 .timer_wait_running = common_timer_wait_running,
1522 .timer_arm = common_hrtimer_arm,
1523 };
1524
1525 static const struct k_clock * const posix_clocks[] = {
1526 [CLOCK_REALTIME] = &clock_realtime,
1527 [CLOCK_MONOTONIC] = &clock_monotonic,
1528 [CLOCK_PROCESS_CPUTIME_ID] = &clock_process,
1529 [CLOCK_THREAD_CPUTIME_ID] = &clock_thread,
1530 [CLOCK_MONOTONIC_RAW] = &clock_monotonic_raw,
1531 [CLOCK_REALTIME_COARSE] = &clock_realtime_coarse,
1532 [CLOCK_MONOTONIC_COARSE] = &clock_monotonic_coarse,
1533 [CLOCK_BOOTTIME] = &clock_boottime,
1534 [CLOCK_REALTIME_ALARM] = &alarm_clock,
1535 [CLOCK_BOOTTIME_ALARM] = &alarm_clock,
1536 [CLOCK_TAI] = &clock_tai,
1537 };
1538
clockid_to_kclock(const clockid_t id)1539 static const struct k_clock *clockid_to_kclock(const clockid_t id)
1540 {
1541 clockid_t idx = id;
1542
1543 if (id < 0) {
1544 return (id & CLOCKFD_MASK) == CLOCKFD ?
1545 &clock_posix_dynamic : &clock_posix_cpu;
1546 }
1547
1548 if (id >= ARRAY_SIZE(posix_clocks))
1549 return NULL;
1550
1551 return posix_clocks[array_index_nospec(idx, ARRAY_SIZE(posix_clocks))];
1552 }
1553
posixtimer_init(void)1554 static int __init posixtimer_init(void)
1555 {
1556 unsigned long i, size;
1557 unsigned int shift;
1558
1559 if (IS_ENABLED(CONFIG_BASE_SMALL))
1560 size = 512;
1561 else
1562 size = roundup_pow_of_two(512 * num_possible_cpus());
1563
1564 timer_buckets = alloc_large_system_hash("posixtimers", sizeof(*timer_buckets),
1565 size, 0, 0, &shift, NULL, size, size);
1566 size = 1UL << shift;
1567 timer_hashmask = size - 1;
1568
1569 for (i = 0; i < size; i++) {
1570 spin_lock_init(&timer_buckets[i].lock);
1571 INIT_HLIST_HEAD(&timer_buckets[i].head);
1572 }
1573 return 0;
1574 }
1575 core_initcall(posixtimer_init);
1576