Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1367 insertions, 0 deletions

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
new file mode 100644
index 000000000..48758108e
--- /dev/null
+++ b/kernel/time/posix-timers.c
@@ -0,0 +1,1367 @@
+/*
+ * linux/kernel/posix-timers.c
+ *
+ *
+ * 2002-10-15  Posix Clocks & timers
+ *                           by George Anzinger george@mvista.com
+ *
+ *			     Copyright (C) 2002 2003 by MontaVista Software.
+ *
+ * 2004-06-01  Fix CLOCK_REALTIME clock/timer TIMER_ABSTIME bug.
+ *			     Copyright (C) 2004 Boris Hu
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * MontaVista Software | 1237 East Arques Avenue | Sunnyvale | CA 94085 | USA
+ */
+
+/* These are all the functions necessary to implement
+ * POSIX clocks & timers
+ */
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/mutex.h>
+#include <linux/sched/task.h>
+
+#include <linux/uaccess.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/compiler.h>
+#include <linux/hash.h>
+#include <linux/posix-clock.h>
+#include <linux/posix-timers.h>
+#include <linux/syscalls.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include <linux/export.h>
+#include <linux/hashtable.h>
+#include <linux/compat.h>
+#include <linux/nospec.h>
+
+#include "timekeeping.h"
+#include "posix-timers.h"
+
+/*
+ * Management arrays for POSIX timers. Timers are now kept in static hash table
+ * with 512 entries.
+ * Timer ids are allocated by local routine, which selects proper hash head by
+ * key, constructed from current->signal address and per signal struct counter.
+ * This keeps timer ids unique per process, but now they can intersect between
+ * processes.
+ */
+
+/*
+ * Lets keep our timers in a slab cache :-)
+ */
+static struct kmem_cache *posix_timers_cache;
+
+static DEFINE_HASHTABLE(posix_timers_hashtable, 9);
+static DEFINE_SPINLOCK(hash_lock);
+
+static const struct k_clock * const posix_clocks[];
+static const struct k_clock *clockid_to_kclock(const clockid_t id);
+static const struct k_clock clock_realtime, clock_monotonic;
+
+/*
+ * we assume that the new SIGEV_THREAD_ID shares no bits with the other
+ * SIGEV values.  Here we put out an error if this assumption fails.
+ */
+#if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \
+                       ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD))
+#error "SIGEV_THREAD_ID must not share bit with other SIGEV values!"
+#endif
+
+/*
+ * The timer ID is turned into a timer address by idr_find().
+ * Verifying a valid ID consists of:
+ *
+ * a) checking that idr_find() returns other than -1.
+ * b) checking that the timer id matches the one in the timer itself.
+ * c) that the timer owner is in the callers thread group.
+ */
+
+/*
+ * CLOCKs: The POSIX standard calls for a couple of clocks and allows us
+ *	    to implement others.  This structure defines the various
+ *	    clocks.
+ *
+ * RESOLUTION: Clock resolution is used to round up timer and interval
+ *	    times, NOT to report clock times, which are reported with as
+ *	    much resolution as the system can muster.  In some cases this
+ *	    resolution may depend on the underlying clock hardware and
+ *	    may not be quantifiable until run time, and only then is the
+ *	    necessary code is written.	The standard says we should say
+ *	    something about this issue in the documentation...
+ *
+ * FUNCTIONS: The CLOCKs structure defines possible functions to
+ *	    handle various clock functions.
+ *
+ *	    The standard POSIX timer management code assumes the
+ *	    following: 1.) The k_itimer struct (sched.h) is used for
+ *	    the timer.  2.) The list, it_lock, it_clock, it_id and
+ *	    it_pid fields are not modified by timer code.
+ *
+ * Permissions: It is assumed that the clock_settime() function defined
+ *	    for each clock will take care of permission checks.	 Some
+ *	    clocks may be set able by any user (i.e. local process
+ *	    clocks) others not.	 Currently the only set able clock we
+ *	    have is CLOCK_REALTIME and its high res counter part, both of
+ *	    which we beg off on and pass to do_sys_settimeofday().
+ */
+static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
+
+#define lock_timer(tid, flags)						   \
+({	struct k_itimer *__timr;					   \
+	__cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags));  \
+	__timr;								   \
+})
+
+static int hash(struct signal_struct *sig, unsigned int nr)
+{
+	return hash_32(hash32_ptr(sig) ^ nr, HASH_BITS(posix_timers_hashtable));
+}
+
+static struct k_itimer *__posix_timers_find(struct hlist_head *head,
+					    struct signal_struct *sig,
+					    timer_t id)
+{
+	struct k_itimer *timer;
+
+	hlist_for_each_entry_rcu(timer, head, t_hash) {
+		if ((timer->it_signal == sig) && (timer->it_id == id))
+			return timer;
+	}
+	return NULL;
+}
+
+static struct k_itimer *posix_timer_by_id(timer_t id)
+{
+	struct signal_struct *sig = current->signal;
+	struct hlist_head *head = &posix_timers_hashtable[hash(sig, id)];
+
+	return __posix_timers_find(head, sig, id);
+}
+
+static int posix_timer_add(struct k_itimer *timer)
+{
+	struct signal_struct *sig = current->signal;
+	int first_free_id = sig->posix_timer_id;
+	struct hlist_head *head;
+	int ret = -ENOENT;
+
+	do {
+		spin_lock(&hash_lock);
+		head = &posix_timers_hashtable[hash(sig, sig->posix_timer_id)];
+		if (!__posix_timers_find(head, sig, sig->posix_timer_id)) {
+			hlist_add_head_rcu(&timer->t_hash, head);
+			ret = sig->posix_timer_id;
+		}
+		if (++sig->posix_timer_id < 0)
+			sig->posix_timer_id = 0;
+		if ((sig->posix_timer_id == first_free_id) && (ret == -ENOENT))
+			/* Loop over all possible ids completed */
+			ret = -EAGAIN;
+		spin_unlock(&hash_lock);
+	} while (ret == -ENOENT);
+	return ret;
+}
+
+static inline void unlock_timer(struct k_itimer *timr, unsigned long flags)
+{
+	spin_unlock_irqrestore(&timr->it_lock, flags);
+}
+
+/* Get clock_realtime */
+static int posix_clock_realtime_get(clockid_t which_clock, struct timespec64 *tp)
+{
+	ktime_get_real_ts64(tp);
+	return 0;
+}
+
+/* Set clock_realtime */
+static int posix_clock_realtime_set(const clockid_t which_clock,
+				    const struct timespec64 *tp)
+{
+	return do_sys_settimeofday64(tp, NULL);
+}
+
+static int posix_clock_realtime_adj(const clockid_t which_clock,
+				    struct timex *t)
+{
+	return do_adjtimex(t);
+}
+
+/*
+ * Get monotonic time for posix timers
+ */
+static int posix_ktime_get_ts(clockid_t which_clock, struct timespec64 *tp)
+{
+	ktime_get_ts64(tp);
+	return 0;
+}
+
+/*
+ * Get monotonic-raw time for posix timers
+ */
+static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec64 *tp)
+{
+	ktime_get_raw_ts64(tp);
+	return 0;
+}
+
+
+static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec64 *tp)
+{
+	ktime_get_coarse_real_ts64(tp);
+	return 0;
+}
+
+static int posix_get_monotonic_coarse(clockid_t which_clock,
+						struct timespec64 *tp)
+{
+	ktime_get_coarse_ts64(tp);
+	return 0;
+}
+
+static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *tp)
+{
+	*tp = ktime_to_timespec64(KTIME_LOW_RES);
+	return 0;
+}
+
+static int posix_get_boottime(const clockid_t which_clock, struct timespec64 *tp)
+{
+	ktime_get_boottime_ts64(tp);
+	return 0;
+}
+
+static int posix_get_tai(clockid_t which_clock, struct timespec64 *tp)
+{
+	ktime_get_clocktai_ts64(tp);
+	return 0;
+}
+
+static int posix_get_hrtimer_res(clockid_t which_clock, struct timespec64 *tp)
+{
+	tp->tv_sec = 0;
+	tp->tv_nsec = hrtimer_resolution;
+	return 0;
+}
+
+/*
+ * Initialize everything, well, just everything in Posix clocks/timers ;)
+ */
+static __init int init_posix_timers(void)
+{
+	posix_timers_cache = kmem_cache_create("posix_timers_cache",
+					sizeof (struct k_itimer), 0, SLAB_PANIC,
+					NULL);
+	return 0;
+}
+__initcall(init_posix_timers);
+
+/*
+ * The siginfo si_overrun field and the return value of timer_getoverrun(2)
+ * are of type int. Clamp the overrun value to INT_MAX
+ */
+static inline int timer_overrun_to_int(struct k_itimer *timr, int baseval)
+{
+	s64 sum = timr->it_overrun_last + (s64)baseval;
+
+	return sum > (s64)INT_MAX ? INT_MAX : (int)sum;
+}
+
+static void common_hrtimer_rearm(struct k_itimer *timr)
+{
+	struct hrtimer *timer = &timr->it.real.timer;
+
+	timr->it_overrun += hrtimer_forward(timer, timer->base->get_time(),
+					    timr->it_interval);
+	hrtimer_restart(timer);
+}
+
+/*
+ * This function is exported for use by the signal deliver code.  It is
+ * called just prior to the info block being released and passes that
+ * block to us.  It's function is to update the overrun entry AND to
+ * restart the timer.  It should only be called if the timer is to be
+ * restarted (i.e. we have flagged this in the sys_private entry of the
+ * info block).
+ *
+ * To protect against the timer going away while the interrupt is queued,
+ * we require that the it_requeue_pending flag be set.
+ */
+void posixtimer_rearm(struct siginfo *info)
+{
+	struct k_itimer *timr;
+	unsigned long flags;
+
+	timr = lock_timer(info->si_tid, &flags);
+	if (!timr)
+		return;
+
+	if (timr->it_interval && timr->it_requeue_pending == info->si_sys_private) {
+		timr->kclock->timer_rearm(timr);
+
+		timr->it_active = 1;
+		timr->it_overrun_last = timr->it_overrun;
+		timr->it_overrun = -1LL;
+		++timr->it_requeue_pending;
+
+		info->si_overrun = timer_overrun_to_int(timr, info->si_overrun);
+	}
+
+	unlock_timer(timr, flags);
+}
+
+int posix_timer_event(struct k_itimer *timr, int si_private)
+{
+	enum pid_type type;
+	int ret = -1;
+	/*
+	 * FIXME: if ->sigq is queued we can race with
+	 * dequeue_signal()->posixtimer_rearm().
+	 *
+	 * If dequeue_signal() sees the "right" value of
+	 * si_sys_private it calls posixtimer_rearm().
+	 * We re-queue ->sigq and drop ->it_lock().
+	 * posixtimer_rearm() locks the timer
+	 * and re-schedules it while ->sigq is pending.
+	 * Not really bad, but not that we want.
+	 */
+	timr->sigq->info.si_sys_private = si_private;
+
+	type = !(timr->it_sigev_notify & SIGEV_THREAD_ID) ? PIDTYPE_TGID : PIDTYPE_PID;
+	ret = send_sigqueue(timr->sigq, timr->it_pid, type);
+	/* If we failed to send the signal the timer stops. */
+	return ret > 0;
+}
+
+/*
+ * This function gets called when a POSIX.1b interval timer expires.  It
+ * is used as a callback from the kernel internal timer.  The
+ * run_timer_list code ALWAYS calls with interrupts on.
+
+ * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
+ */
+static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
+{
+	struct k_itimer *timr;
+	unsigned long flags;
+	int si_private = 0;
+	enum hrtimer_restart ret = HRTIMER_NORESTART;
+
+	timr = container_of(timer, struct k_itimer, it.real.timer);
+	spin_lock_irqsave(&timr->it_lock, flags);
+
+	timr->it_active = 0;
+	if (timr->it_interval != 0)
+		si_private = ++timr->it_requeue_pending;
+
+	if (posix_timer_event(timr, si_private)) {
+		/*
+		 * signal was not sent because of sig_ignor
+		 * we will not get a call back to restart it AND
+		 * it should be restarted.
+		 */
+		if (timr->it_interval != 0) {
+			ktime_t now = hrtimer_cb_get_time(timer);
+
+			/*
+			 * FIXME: What we really want, is to stop this
+			 * timer completely and restart it in case the
+			 * SIG_IGN is removed. This is a non trivial
+			 * change which involves sighand locking
+			 * (sigh !), which we don't want to do late in
+			 * the release cycle.
+			 *
+			 * For now we just let timers with an interval
+			 * less than a jiffie expire every jiffie to
+			 * avoid softirq starvation in case of SIG_IGN
+			 * and a very small interval, which would put
+			 * the timer right back on the softirq pending
+			 * list. By moving now ahead of time we trick
+			 * hrtimer_forward() to expire the timer
+			 * later, while we still maintain the overrun
+			 * accuracy, but have some inconsistency in
+			 * the timer_gettime() case. This is at least
+			 * better than a starved softirq. A more
+			 * complex fix which solves also another related
+			 * inconsistency is already in the pipeline.
+			 */
+#ifdef CONFIG_HIGH_RES_TIMERS
+			{
+				ktime_t kj = NSEC_PER_SEC / HZ;
+
+				if (timr->it_interval < kj)
+					now = ktime_add(now, kj);
+			}
+#endif
+			timr->it_overrun += hrtimer_forward(timer, now,
+							    timr->it_interval);
+			ret = HRTIMER_RESTART;
+			++timr->it_requeue_pending;
+			timr->it_active = 1;
+		}
+	}
+
+	unlock_timer(timr, flags);
+	return ret;
+}
+
+static struct pid *good_sigevent(sigevent_t * event)
+{
+	struct pid *pid = task_tgid(current);
+	struct task_struct *rtn;
+
+	switch (event->sigev_notify) {
+	case SIGEV_SIGNAL | SIGEV_THREAD_ID:
+		pid = find_vpid(event->sigev_notify_thread_id);
+		rtn = pid_task(pid, PIDTYPE_PID);
+		if (!rtn || !same_thread_group(rtn, current))
+			return NULL;
+		/* FALLTHRU */
+	case SIGEV_SIGNAL:
+	case SIGEV_THREAD:
+		if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
+			return NULL;
+		/* FALLTHRU */
+	case SIGEV_NONE:
+		return pid;
+	default:
+		return NULL;
+	}
+}
+
+static struct k_itimer * alloc_posix_timer(void)
+{
+	struct k_itimer *tmr;
+	tmr = kmem_cache_zalloc(posix_timers_cache, GFP_KERNEL);
+	if (!tmr)
+		return tmr;
+	if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
+		kmem_cache_free(posix_timers_cache, tmr);
+		return NULL;
+	}
+	clear_siginfo(&tmr->sigq->info);
+	return tmr;
+}
+
+static void k_itimer_rcu_free(struct rcu_head *head)
+{
+	struct k_itimer *tmr = container_of(head, struct k_itimer, it.rcu);
+
+	kmem_cache_free(posix_timers_cache, tmr);
+}
+
+#define IT_ID_SET	1
+#define IT_ID_NOT_SET	0
+static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
+{
+	if (it_id_set) {
+		unsigned long flags;
+		spin_lock_irqsave(&hash_lock, flags);
+		hlist_del_rcu(&tmr->t_hash);
+		spin_unlock_irqrestore(&hash_lock, flags);
+	}
+	put_pid(tmr->it_pid);
+	sigqueue_free(tmr->sigq);
+	call_rcu(&tmr->it.rcu, k_itimer_rcu_free);
+}
+
+static int common_timer_create(struct k_itimer *new_timer)
+{
+	hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
+	return 0;
+}
+
+/* Create a POSIX.1b interval timer. */
+static int do_timer_create(clockid_t which_clock, struct sigevent *event,
+			   timer_t __user *created_timer_id)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct k_itimer *new_timer;
+	int error, new_timer_id;
+	int it_id_set = IT_ID_NOT_SET;
+
+	if (!kc)
+		return -EINVAL;
+	if (!kc->timer_create)
+		return -EOPNOTSUPP;
+
+	new_timer = alloc_posix_timer();
+	if (unlikely(!new_timer))
+		return -EAGAIN;
+
+	spin_lock_init(&new_timer->it_lock);
+	new_timer_id = posix_timer_add(new_timer);
+	if (new_timer_id < 0) {
+		error = new_timer_id;
+		goto out;
+	}
+
+	it_id_set = IT_ID_SET;
+	new_timer->it_id = (timer_t) new_timer_id;
+	new_timer->it_clock = which_clock;
+	new_timer->kclock = kc;
+	new_timer->it_overrun = -1LL;
+
+	if (event) {
+		rcu_read_lock();
+		new_timer->it_pid = get_pid(good_sigevent(event));
+		rcu_read_unlock();
+		if (!new_timer->it_pid) {
+			error = -EINVAL;
+			goto out;
+		}
+		new_timer->it_sigev_notify     = event->sigev_notify;
+		new_timer->sigq->info.si_signo = event->sigev_signo;
+		new_timer->sigq->info.si_value = event->sigev_value;
+	} else {
+		new_timer->it_sigev_notify     = SIGEV_SIGNAL;
+		new_timer->sigq->info.si_signo = SIGALRM;
+		memset(&new_timer->sigq->info.si_value, 0, sizeof(sigval_t));
+		new_timer->sigq->info.si_value.sival_int = new_timer->it_id;
+		new_timer->it_pid = get_pid(task_tgid(current));
+	}
+
+	new_timer->sigq->info.si_tid   = new_timer->it_id;
+	new_timer->sigq->info.si_code  = SI_TIMER;
+
+	if (copy_to_user(created_timer_id,
+			 &new_timer_id, sizeof (new_timer_id))) {
+		error = -EFAULT;
+		goto out;
+	}
+
+	error = kc->timer_create(new_timer);
+	if (error)
+		goto out;
+
+	spin_lock_irq(&current->sighand->siglock);
+	new_timer->it_signal = current->signal;
+	list_add(&new_timer->list, &current->signal->posix_timers);
+	spin_unlock_irq(&current->sighand->siglock);
+
+	return 0;
+	/*
+	 * In the case of the timer belonging to another task, after
+	 * the task is unlocked, the timer is owned by the other task
+	 * and may cease to exist at any time.  Don't use or modify
+	 * new_timer after the unlock call.
+	 */
+out:
+	release_posix_timer(new_timer, it_id_set);
+	return error;
+}
+
+SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
+		struct sigevent __user *, timer_event_spec,
+		timer_t __user *, created_timer_id)
+{
+	if (timer_event_spec) {
+		sigevent_t event;
+
+		if (copy_from_user(&event, timer_event_spec, sizeof (event)))
+			return -EFAULT;
+		return do_timer_create(which_clock, &event, created_timer_id);
+	}
+	return do_timer_create(which_clock, NULL, created_timer_id);
+}
+
+#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)
+{
+	if (timer_event_spec) {
+		sigevent_t event;
+
+		if (get_compat_sigevent(&event, timer_event_spec))
+			return -EFAULT;
+		return do_timer_create(which_clock, &event, created_timer_id);
+	}
+	return do_timer_create(which_clock, NULL, created_timer_id);
+}
+#endif
+
+/*
+ * Locking issues: We need to protect the result of the id look up until
+ * we get the timer locked down so it is not deleted under us.  The
+ * removal is done under the idr spinlock so we use that here to bridge
+ * the find to the timer lock.  To avoid a dead lock, the timer id MUST
+ * be release with out holding the timer lock.
+ */
+static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags)
+{
+	struct k_itimer *timr;
+
+	/*
+	 * timer_t could be any type >= int and we want to make sure any
+	 * @timer_id outside positive int range fails lookup.
+	 */
+	if ((unsigned long long)timer_id > INT_MAX)
+		return NULL;
+
+	rcu_read_lock();
+	timr = posix_timer_by_id(timer_id);
+	if (timr) {
+		spin_lock_irqsave(&timr->it_lock, *flags);
+		if (timr->it_signal == current->signal) {
+			rcu_read_unlock();
+			return timr;
+		}
+		spin_unlock_irqrestore(&timr->it_lock, *flags);
+	}
+	rcu_read_unlock();
+
+	return NULL;
+}
+
+static ktime_t common_hrtimer_remaining(struct k_itimer *timr, ktime_t now)
+{
+	struct hrtimer *timer = &timr->it.real.timer;
+
+	return __hrtimer_expires_remaining_adjusted(timer, now);
+}
+
+static s64 common_hrtimer_forward(struct k_itimer *timr, ktime_t now)
+{
+	struct hrtimer *timer = &timr->it.real.timer;
+
+	return hrtimer_forward(timer, now, timr->it_interval);
+}
+
+/*
+ * Get the time remaining on a POSIX.1b interval timer.  This function
+ * is ALWAYS called with spin_lock_irq on the timer, thus it must not
+ * mess with irq.
+ *
+ * We have a couple of messes to clean up here.  First there is the case
+ * of a timer that has a requeue pending.  These timers should appear to
+ * be in the timer list with an expiry as if we were to requeue them
+ * now.
+ *
+ * The second issue is the SIGEV_NONE timer which may be active but is
+ * not really ever put in the timer list (to save system resources).
+ * This timer may be expired, and if so, we will do it here.  Otherwise
+ * it is the same as a requeue pending timer WRT to what we should
+ * report.
+ */
+void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
+{
+	const struct k_clock *kc = timr->kclock;
+	ktime_t now, remaining, iv;
+	struct timespec64 ts64;
+	bool sig_none;
+
+	sig_none = timr->it_sigev_notify == SIGEV_NONE;
+	iv = timr->it_interval;
+
+	/* interval timer ? */
+	if (iv) {
+		cur_setting->it_interval = ktime_to_timespec64(iv);
+	} else if (!timr->it_active) {
+		/*
+		 * SIGEV_NONE oneshot timers are never queued. Check them
+		 * below.
+		 */
+		if (!sig_none)
+			return;
+	}
+
+	/*
+	 * The timespec64 based conversion is suboptimal, but it's not
+	 * worth to implement yet another callback.
+	 */
+	kc->clock_get(timr->it_clock, &ts64);
+	now = timespec64_to_ktime(ts64);
+
+	/*
+	 * When a requeue is pending or this is a SIGEV_NONE timer move the
+	 * expiry time forward by intervals, so expiry is > now.
+	 */
+	if (iv && (timr->it_requeue_pending & REQUEUE_PENDING || sig_none))
+		timr->it_overrun += kc->timer_forward(timr, now);
+
+	remaining = kc->timer_remaining(timr, now);
+	/* Return 0 only, when the timer is expired and not pending */
+	if (remaining <= 0) {
+		/*
+		 * A single shot SIGEV_NONE timer must return 0, when
+		 * it is expired !
+		 */
+		if (!sig_none)
+			cur_setting->it_value.tv_nsec = 1;
+	} else {
+		cur_setting->it_value = ktime_to_timespec64(remaining);
+	}
+}
+
+/* Get the time remaining on a POSIX.1b interval timer. */
+static int do_timer_gettime(timer_t timer_id,  struct itimerspec64 *setting)
+{
+	struct k_itimer *timr;
+	const struct k_clock *kc;
+	unsigned long flags;
+	int ret = 0;
+
+	timr = lock_timer(timer_id, &flags);
+	if (!timr)
+		return -EINVAL;
+
+	memset(setting, 0, sizeof(*setting));
+	kc = timr->kclock;
+	if (WARN_ON_ONCE(!kc || !kc->timer_get))
+		ret = -EINVAL;
+	else
+		kc->timer_get(timr, setting);
+
+	unlock_timer(timr, flags);
+	return ret;
+}
+
+/* Get the time remaining on a POSIX.1b interval timer. */
+SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
+		struct __kernel_itimerspec __user *, setting)
+{
+	struct itimerspec64 cur_setting;
+
+	int ret = do_timer_gettime(timer_id, &cur_setting);
+	if (!ret) {
+		if (put_itimerspec64(&cur_setting, setting))
+			ret = -EFAULT;
+	}
+	return ret;
+}
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+
+COMPAT_SYSCALL_DEFINE2(timer_gettime, timer_t, timer_id,
+		       struct compat_itimerspec __user *, setting)
+{
+	struct itimerspec64 cur_setting;
+
+	int ret = do_timer_gettime(timer_id, &cur_setting);
+	if (!ret) {
+		if (put_compat_itimerspec64(&cur_setting, setting))
+			ret = -EFAULT;
+	}
+	return ret;
+}
+
+#endif
+
+/*
+ * Get the number of overruns of a POSIX.1b interval timer.  This is to
+ * be the overrun of the timer last delivered.  At the same time we are
+ * accumulating overruns on the next timer.  The overrun is frozen when
+ * the signal is delivered, either at the notify time (if the info block
+ * is not queued) or at the actual delivery time (as we are informed by
+ * the call back to posixtimer_rearm().  So all we need to do is
+ * to pick up the frozen overrun.
+ */
+SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
+{
+	struct k_itimer *timr;
+	int overrun;
+	unsigned long flags;
+
+	timr = lock_timer(timer_id, &flags);
+	if (!timr)
+		return -EINVAL;
+
+	overrun = timer_overrun_to_int(timr, 0);
+	unlock_timer(timr, flags);
+
+	return overrun;
+}
+
+static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
+			       bool absolute, bool sigev_none)
+{
+	struct hrtimer *timer = &timr->it.real.timer;
+	enum hrtimer_mode mode;
+
+	mode = absolute ? HRTIMER_MODE_ABS : HRTIMER_MODE_REL;
+	/*
+	 * Posix magic: Relative CLOCK_REALTIME timers are not affected by
+	 * clock modifications, so they become CLOCK_MONOTONIC based under the
+	 * hood. See hrtimer_init(). Update timr->kclock, so the generic
+	 * functions which use timr->kclock->clock_get() work.
+	 *
+	 * Note: it_clock stays unmodified, because the next timer_set() might
+	 * use ABSTIME, so it needs to switch back.
+	 */
+	if (timr->it_clock == CLOCK_REALTIME)
+		timr->kclock = absolute ? &clock_realtime : &clock_monotonic;
+
+	hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
+	timr->it.real.timer.function = posix_timer_fn;
+
+	if (!absolute)
+		expires = ktime_add_safe(expires, timer->base->get_time());
+	hrtimer_set_expires(timer, expires);
+
+	if (!sigev_none)
+		hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
+}
+
+static int common_hrtimer_try_to_cancel(struct k_itimer *timr)
+{
+	return hrtimer_try_to_cancel(&timr->it.real.timer);
+}
+
+/* Set a POSIX.1b interval timer. */
+int common_timer_set(struct k_itimer *timr, int flags,
+		     struct itimerspec64 *new_setting,
+		     struct itimerspec64 *old_setting)
+{
+	const struct k_clock *kc = timr->kclock;
+	bool sigev_none;
+	ktime_t expires;
+
+	if (old_setting)
+		common_timer_get(timr, old_setting);
+
+	/* Prevent rearming by clearing the interval */
+	timr->it_interval = 0;
+	/*
+	 * Careful here. On SMP systems the timer expiry function could be
+	 * active and spinning on timr->it_lock.
+	 */
+	if (kc->timer_try_to_cancel(timr) < 0)
+		return TIMER_RETRY;
+
+	timr->it_active = 0;
+	timr->it_requeue_pending = (timr->it_requeue_pending + 2) &
+		~REQUEUE_PENDING;
+	timr->it_overrun_last = 0;
+
+	/* Switch off the timer when it_value is zero */
+	if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec)
+		return 0;
+
+	timr->it_interval = timespec64_to_ktime(new_setting->it_interval);
+	expires = timespec64_to_ktime(new_setting->it_value);
+	sigev_none = timr->it_sigev_notify == SIGEV_NONE;
+
+	kc->timer_arm(timr, expires, flags & TIMER_ABSTIME, sigev_none);
+	timr->it_active = !sigev_none;
+	return 0;
+}
+
+static int do_timer_settime(timer_t timer_id, int flags,
+			    struct itimerspec64 *new_spec64,
+			    struct itimerspec64 *old_spec64)
+{
+	const struct k_clock *kc;
+	struct k_itimer *timr;
+	unsigned long flag;
+	int error = 0;
+
+	if (!timespec64_valid(&new_spec64->it_interval) ||
+	    !timespec64_valid(&new_spec64->it_value))
+		return -EINVAL;
+
+	if (old_spec64)
+		memset(old_spec64, 0, sizeof(*old_spec64));
+retry:
+	timr = lock_timer(timer_id, &flag);
+	if (!timr)
+		return -EINVAL;
+
+	kc = timr->kclock;
+	if (WARN_ON_ONCE(!kc || !kc->timer_set))
+		error = -EINVAL;
+	else
+		error = kc->timer_set(timr, flags, new_spec64, old_spec64);
+
+	unlock_timer(timr, flag);
+	if (error == TIMER_RETRY) {
+		old_spec64 = NULL;	// We already got the old time...
+		goto retry;
+	}
+
+	return error;
+}
+
+/* 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)
+{
+	struct itimerspec64 new_spec, old_spec;
+	struct itimerspec64 *rtn = old_setting ? &old_spec : NULL;
+	int error = 0;
+
+	if (!new_setting)
+		return -EINVAL;
+
+	if (get_itimerspec64(&new_spec, new_setting))
+		return -EFAULT;
+
+	error = do_timer_settime(timer_id, flags, &new_spec, rtn);
+	if (!error && old_setting) {
+		if (put_itimerspec64(&old_spec, old_setting))
+			error = -EFAULT;
+	}
+	return error;
+}
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+COMPAT_SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
+		       struct compat_itimerspec __user *, new,
+		       struct compat_itimerspec __user *, old)
+{
+	struct itimerspec64 new_spec, old_spec;
+	struct itimerspec64 *rtn = old ? &old_spec : NULL;
+	int error = 0;
+
+	if (!new)
+		return -EINVAL;
+	if (get_compat_itimerspec64(&new_spec, new))
+		return -EFAULT;
+
+	error = do_timer_settime(timer_id, flags, &new_spec, rtn);
+	if (!error && old) {
+		if (put_compat_itimerspec64(&old_spec, old))
+			error = -EFAULT;
+	}
+	return error;
+}
+#endif
+
+int common_timer_del(struct k_itimer *timer)
+{
+	const struct k_clock *kc = timer->kclock;
+
+	timer->it_interval = 0;
+	if (kc->timer_try_to_cancel(timer) < 0)
+		return TIMER_RETRY;
+	timer->it_active = 0;
+	return 0;
+}
+
+static inline int timer_delete_hook(struct k_itimer *timer)
+{
+	const struct k_clock *kc = timer->kclock;
+
+	if (WARN_ON_ONCE(!kc || !kc->timer_del))
+		return -EINVAL;
+	return kc->timer_del(timer);
+}
+
+/* Delete a POSIX.1b interval timer. */
+SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
+{
+	struct k_itimer *timer;
+	unsigned long flags;
+
+retry_delete:
+	timer = lock_timer(timer_id, &flags);
+	if (!timer)
+		return -EINVAL;
+
+	if (timer_delete_hook(timer) == TIMER_RETRY) {
+		unlock_timer(timer, flags);
+		goto retry_delete;
+	}
+
+	spin_lock(&current->sighand->siglock);
+	list_del(&timer->list);
+	spin_unlock(&current->sighand->siglock);
+	/*
+	 * This keeps any tasks waiting on the spin lock from thinking
+	 * they got something (see the lock code above).
+	 */
+	timer->it_signal = NULL;
+
+	unlock_timer(timer, flags);
+	release_posix_timer(timer, IT_ID_SET);
+	return 0;
+}
+
+/*
+ * return timer owned by the process, used by exit_itimers
+ */
+static void itimer_delete(struct k_itimer *timer)
+{
+	unsigned long flags;
+
+retry_delete:
+	spin_lock_irqsave(&timer->it_lock, flags);
+
+	if (timer_delete_hook(timer) == TIMER_RETRY) {
+		unlock_timer(timer, flags);
+		goto retry_delete;
+	}
+	list_del(&timer->list);
+	/*
+	 * This keeps any tasks waiting on the spin lock from thinking
+	 * they got something (see the lock code above).
+	 */
+	timer->it_signal = NULL;
+
+	unlock_timer(timer, flags);
+	release_posix_timer(timer, IT_ID_SET);
+}
+
+/*
+ * This is called by do_exit or de_thread, only when there are no more
+ * references to the shared signal_struct.
+ */
+void exit_itimers(struct signal_struct *sig)
+{
+	struct k_itimer *tmr;
+
+	while (!list_empty(&sig->posix_timers)) {
+		tmr = list_entry(sig->posix_timers.next, struct k_itimer, list);
+		itimer_delete(tmr);
+	}
+}
+
+SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
+		const struct __kernel_timespec __user *, tp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timespec64 new_tp;
+
+	if (!kc || !kc->clock_set)
+		return -EINVAL;
+
+	if (get_timespec64(&new_tp, tp))
+		return -EFAULT;
+
+	return kc->clock_set(which_clock, &new_tp);
+}
+
+SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
+		struct __kernel_timespec __user *, tp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timespec64 kernel_tp;
+	int error;
+
+	if (!kc)
+		return -EINVAL;
+
+	error = kc->clock_get(which_clock, &kernel_tp);
+
+	if (!error && put_timespec64(&kernel_tp, tp))
+		error = -EFAULT;
+
+	return error;
+}
+
+SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
+		struct timex __user *, utx)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timex ktx;
+	int err;
+
+	if (!kc)
+		return -EINVAL;
+	if (!kc->clock_adj)
+		return -EOPNOTSUPP;
+
+	if (copy_from_user(&ktx, utx, sizeof(ktx)))
+		return -EFAULT;
+
+	err = kc->clock_adj(which_clock, &ktx);
+
+	if (err >= 0 && copy_to_user(utx, &ktx, sizeof(ktx)))
+		return -EFAULT;
+
+	return err;
+}
+
+SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
+		struct __kernel_timespec __user *, tp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timespec64 rtn_tp;
+	int error;
+
+	if (!kc)
+		return -EINVAL;
+
+	error = kc->clock_getres(which_clock, &rtn_tp);
+
+	if (!error && tp && put_timespec64(&rtn_tp, tp))
+		error = -EFAULT;
+
+	return error;
+}
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+
+COMPAT_SYSCALL_DEFINE2(clock_settime, clockid_t, which_clock,
+		       struct compat_timespec __user *, tp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timespec64 ts;
+
+	if (!kc || !kc->clock_set)
+		return -EINVAL;
+
+	if (compat_get_timespec64(&ts, tp))
+		return -EFAULT;
+
+	return kc->clock_set(which_clock, &ts);
+}
+
+COMPAT_SYSCALL_DEFINE2(clock_gettime, clockid_t, which_clock,
+		       struct compat_timespec __user *, tp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timespec64 ts;
+	int err;
+
+	if (!kc)
+		return -EINVAL;
+
+	err = kc->clock_get(which_clock, &ts);
+
+	if (!err && compat_put_timespec64(&ts, tp))
+		err = -EFAULT;
+
+	return err;
+}
+
+#endif
+
+#ifdef CONFIG_COMPAT
+
+COMPAT_SYSCALL_DEFINE2(clock_adjtime, clockid_t, which_clock,
+		       struct compat_timex __user *, utp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timex ktx;
+	int err;
+
+	if (!kc)
+		return -EINVAL;
+	if (!kc->clock_adj)
+		return -EOPNOTSUPP;
+
+	err = compat_get_timex(&ktx, utp);
+	if (err)
+		return err;
+
+	err = kc->clock_adj(which_clock, &ktx);
+
+	if (err >= 0 && compat_put_timex(utp, &ktx))
+		return -EFAULT;
+
+	return err;
+}
+
+#endif
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+
+COMPAT_SYSCALL_DEFINE2(clock_getres, clockid_t, which_clock,
+		       struct compat_timespec __user *, tp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timespec64 ts;
+	int err;
+
+	if (!kc)
+		return -EINVAL;
+
+	err = kc->clock_getres(which_clock, &ts);
+	if (!err && tp && compat_put_timespec64(&ts, tp))
+		return -EFAULT;
+
+	return err;
+}
+
+#endif
+
+/*
+ * nanosleep for monotonic and realtime clocks
+ */
+static int common_nsleep(const clockid_t which_clock, int flags,
+			 const struct timespec64 *rqtp)
+{
+	return hrtimer_nanosleep(rqtp, flags & TIMER_ABSTIME ?
+				 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
+				 which_clock);
+}
+
+SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
+		const struct __kernel_timespec __user *, rqtp,
+		struct __kernel_timespec __user *, rmtp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timespec64 t;
+
+	if (!kc)
+		return -EINVAL;
+	if (!kc->nsleep)
+		return -EOPNOTSUPP;
+
+	if (get_timespec64(&t, rqtp))
+		return -EFAULT;
+
+	if (!timespec64_valid(&t))
+		return -EINVAL;
+	if (flags & TIMER_ABSTIME)
+		rmtp = NULL;
+	current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
+	current->restart_block.nanosleep.rmtp = rmtp;
+
+	return kc->nsleep(which_clock, flags, &t);
+}
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+
+COMPAT_SYSCALL_DEFINE4(clock_nanosleep, clockid_t, which_clock, int, flags,
+		       struct compat_timespec __user *, rqtp,
+		       struct compat_timespec __user *, rmtp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timespec64 t;
+
+	if (!kc)
+		return -EINVAL;
+	if (!kc->nsleep)
+		return -EOPNOTSUPP;
+
+	if (compat_get_timespec64(&t, rqtp))
+		return -EFAULT;
+
+	if (!timespec64_valid(&t))
+		return -EINVAL;
+	if (flags & TIMER_ABSTIME)
+		rmtp = NULL;
+	current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
+	current->restart_block.nanosleep.compat_rmtp = rmtp;
+
+	return kc->nsleep(which_clock, flags, &t);
+}
+
+#endif
+
+static const struct k_clock clock_realtime = {
+	.clock_getres		= posix_get_hrtimer_res,
+	.clock_get		= posix_clock_realtime_get,
+	.clock_set		= posix_clock_realtime_set,
+	.clock_adj		= posix_clock_realtime_adj,
+	.nsleep			= common_nsleep,
+	.timer_create		= common_timer_create,
+	.timer_set		= common_timer_set,
+	.timer_get		= common_timer_get,
+	.timer_del		= common_timer_del,
+	.timer_rearm		= common_hrtimer_rearm,
+	.timer_forward		= common_hrtimer_forward,
+	.timer_remaining	= common_hrtimer_remaining,
+	.timer_try_to_cancel	= common_hrtimer_try_to_cancel,
+	.timer_arm		= common_hrtimer_arm,
+};
+
+static const struct k_clock clock_monotonic = {
+	.clock_getres		= posix_get_hrtimer_res,
+	.clock_get		= posix_ktime_get_ts,
+	.nsleep			= common_nsleep,
+	.timer_create		= common_timer_create,
+	.timer_set		= common_timer_set,
+	.timer_get		= common_timer_get,
+	.timer_del		= common_timer_del,
+	.timer_rearm		= common_hrtimer_rearm,
+	.timer_forward		= common_hrtimer_forward,
+	.timer_remaining	= common_hrtimer_remaining,
+	.timer_try_to_cancel	= common_hrtimer_try_to_cancel,
+	.timer_arm		= common_hrtimer_arm,
+};
+
+static const struct k_clock clock_monotonic_raw = {
+	.clock_getres		= posix_get_hrtimer_res,
+	.clock_get		= posix_get_monotonic_raw,
+};
+
+static const struct k_clock clock_realtime_coarse = {
+	.clock_getres		= posix_get_coarse_res,
+	.clock_get		= posix_get_realtime_coarse,
+};
+
+static const struct k_clock clock_monotonic_coarse = {
+	.clock_getres		= posix_get_coarse_res,
+	.clock_get		= posix_get_monotonic_coarse,
+};
+
+static const struct k_clock clock_tai = {
+	.clock_getres		= posix_get_hrtimer_res,
+	.clock_get		= posix_get_tai,
+	.nsleep			= common_nsleep,
+	.timer_create		= common_timer_create,
+	.timer_set		= common_timer_set,
+	.timer_get		= common_timer_get,
+	.timer_del		= common_timer_del,
+	.timer_rearm		= common_hrtimer_rearm,
+	.timer_forward		= common_hrtimer_forward,
+	.timer_remaining	= common_hrtimer_remaining,
+	.timer_try_to_cancel	= common_hrtimer_try_to_cancel,
+	.timer_arm		= common_hrtimer_arm,
+};
+
+static const struct k_clock clock_boottime = {
+	.clock_getres		= posix_get_hrtimer_res,
+	.clock_get		= posix_get_boottime,
+	.nsleep			= common_nsleep,
+	.timer_create		= common_timer_create,
+	.timer_set		= common_timer_set,
+	.timer_get		= common_timer_get,
+	.timer_del		= common_timer_del,
+	.timer_rearm		= common_hrtimer_rearm,
+	.timer_forward		= common_hrtimer_forward,
+	.timer_remaining	= common_hrtimer_remaining,
+	.timer_try_to_cancel	= common_hrtimer_try_to_cancel,
+	.timer_arm		= common_hrtimer_arm,
+};
+
+static const struct k_clock * const posix_clocks[] = {
+	[CLOCK_REALTIME]		= &clock_realtime,
+	[CLOCK_MONOTONIC]		= &clock_monotonic,
+	[CLOCK_PROCESS_CPUTIME_ID]	= &clock_process,
+	[CLOCK_THREAD_CPUTIME_ID]	= &clock_thread,
+	[CLOCK_MONOTONIC_RAW]		= &clock_monotonic_raw,
+	[CLOCK_REALTIME_COARSE]		= &clock_realtime_coarse,
+	[CLOCK_MONOTONIC_COARSE]	= &clock_monotonic_coarse,
+	[CLOCK_BOOTTIME]		= &clock_boottime,
+	[CLOCK_REALTIME_ALARM]		= &alarm_clock,
+	[CLOCK_BOOTTIME_ALARM]		= &alarm_clock,
+	[CLOCK_TAI]			= &clock_tai,
+};
+
+static const struct k_clock *clockid_to_kclock(const clockid_t id)
+{
+	clockid_t idx = id;
+
+	if (id < 0) {
+		return (id & CLOCKFD_MASK) == CLOCKFD ?
+			&clock_posix_dynamic : &clock_posix_cpu;
+	}
+
+	if (id >= ARRAY_SIZE(posix_clocks))
+		return NULL;
+
+	return posix_clocks[array_index_nospec(idx, ARRAY_SIZE(posix_clocks))];
+}