v4.19.13 snapshot.
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
new file mode 100644
index 0000000..ce32cf7
--- /dev/null
+++ b/kernel/time/posix-cpu-timers.c
@@ -0,0 +1,1445 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Implement CPU time clocks for the POSIX clock interface.
+ */
+
+#include <linux/sched/signal.h>
+#include <linux/sched/cputime.h>
+#include <linux/posix-timers.h>
+#include <linux/errno.h>
+#include <linux/math64.h>
+#include <linux/uaccess.h>
+#include <linux/kernel_stat.h>
+#include <trace/events/timer.h>
+#include <linux/tick.h>
+#include <linux/workqueue.h>
+#include <linux/compat.h>
+#include <linux/sched/deadline.h>
+
+#include "posix-timers.h"
+
+static void posix_cpu_timer_rearm(struct k_itimer *timer);
+
+/*
+ * Called after updating RLIMIT_CPU to run cpu timer and update
+ * tsk->signal->cputime_expires expiration cache if necessary. Needs
+ * siglock protection since other code may update expiration cache as
+ * well.
+ */
+void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
+{
+ u64 nsecs = rlim_new * NSEC_PER_SEC;
+
+ spin_lock_irq(&task->sighand->siglock);
+ set_process_cpu_timer(task, CPUCLOCK_PROF, &nsecs, NULL);
+ spin_unlock_irq(&task->sighand->siglock);
+}
+
+static int check_clock(const clockid_t which_clock)
+{
+ int error = 0;
+ struct task_struct *p;
+ const pid_t pid = CPUCLOCK_PID(which_clock);
+
+ if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
+ return -EINVAL;
+
+ if (pid == 0)
+ return 0;
+
+ rcu_read_lock();
+ p = find_task_by_vpid(pid);
+ if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
+ same_thread_group(p, current) : has_group_leader_pid(p))) {
+ error = -EINVAL;
+ }
+ rcu_read_unlock();
+
+ return error;
+}
+
+/*
+ * Update expiry time from increment, and increase overrun count,
+ * given the current clock sample.
+ */
+static void bump_cpu_timer(struct k_itimer *timer, u64 now)
+{
+ int i;
+ u64 delta, incr;
+
+ if (timer->it.cpu.incr == 0)
+ return;
+
+ if (now < timer->it.cpu.expires)
+ return;
+
+ incr = timer->it.cpu.incr;
+ delta = now + incr - timer->it.cpu.expires;
+
+ /* Don't use (incr*2 < delta), incr*2 might overflow. */
+ for (i = 0; incr < delta - incr; i++)
+ incr = incr << 1;
+
+ for (; i >= 0; incr >>= 1, i--) {
+ if (delta < incr)
+ continue;
+
+ timer->it.cpu.expires += incr;
+ timer->it_overrun += 1LL << i;
+ delta -= incr;
+ }
+}
+
+/**
+ * task_cputime_zero - Check a task_cputime struct for all zero fields.
+ *
+ * @cputime: The struct to compare.
+ *
+ * Checks @cputime to see if all fields are zero. Returns true if all fields
+ * are zero, false if any field is nonzero.
+ */
+static inline int task_cputime_zero(const struct task_cputime *cputime)
+{
+ if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
+ return 1;
+ return 0;
+}
+
+static inline u64 prof_ticks(struct task_struct *p)
+{
+ u64 utime, stime;
+
+ task_cputime(p, &utime, &stime);
+
+ return utime + stime;
+}
+static inline u64 virt_ticks(struct task_struct *p)
+{
+ u64 utime, stime;
+
+ task_cputime(p, &utime, &stime);
+
+ return utime;
+}
+
+static int
+posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
+{
+ int error = check_clock(which_clock);
+ if (!error) {
+ tp->tv_sec = 0;
+ tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
+ if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
+ /*
+ * If sched_clock is using a cycle counter, we
+ * don't have any idea of its true resolution
+ * exported, but it is much more than 1s/HZ.
+ */
+ tp->tv_nsec = 1;
+ }
+ }
+ return error;
+}
+
+static int
+posix_cpu_clock_set(const clockid_t which_clock, const struct timespec64 *tp)
+{
+ /*
+ * You can never reset a CPU clock, but we check for other errors
+ * in the call before failing with EPERM.
+ */
+ int error = check_clock(which_clock);
+ if (error == 0) {
+ error = -EPERM;
+ }
+ return error;
+}
+
+
+/*
+ * Sample a per-thread clock for the given task.
+ */
+static int cpu_clock_sample(const clockid_t which_clock,
+ struct task_struct *p, u64 *sample)
+{
+ switch (CPUCLOCK_WHICH(which_clock)) {
+ default:
+ return -EINVAL;
+ case CPUCLOCK_PROF:
+ *sample = prof_ticks(p);
+ break;
+ case CPUCLOCK_VIRT:
+ *sample = virt_ticks(p);
+ break;
+ case CPUCLOCK_SCHED:
+ *sample = task_sched_runtime(p);
+ break;
+ }
+ return 0;
+}
+
+/*
+ * Set cputime to sum_cputime if sum_cputime > cputime. Use cmpxchg
+ * to avoid race conditions with concurrent updates to cputime.
+ */
+static inline void __update_gt_cputime(atomic64_t *cputime, u64 sum_cputime)
+{
+ u64 curr_cputime;
+retry:
+ curr_cputime = atomic64_read(cputime);
+ if (sum_cputime > curr_cputime) {
+ if (atomic64_cmpxchg(cputime, curr_cputime, sum_cputime) != curr_cputime)
+ goto retry;
+ }
+}
+
+static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic, struct task_cputime *sum)
+{
+ __update_gt_cputime(&cputime_atomic->utime, sum->utime);
+ __update_gt_cputime(&cputime_atomic->stime, sum->stime);
+ __update_gt_cputime(&cputime_atomic->sum_exec_runtime, sum->sum_exec_runtime);
+}
+
+/* Sample task_cputime_atomic values in "atomic_timers", store results in "times". */
+static inline void sample_cputime_atomic(struct task_cputime *times,
+ struct task_cputime_atomic *atomic_times)
+{
+ times->utime = atomic64_read(&atomic_times->utime);
+ times->stime = atomic64_read(&atomic_times->stime);
+ times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime);
+}
+
+void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
+{
+ struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+ struct task_cputime sum;
+
+ /* Check if cputimer isn't running. This is accessed without locking. */
+ if (!READ_ONCE(cputimer->running)) {
+ /*
+ * The POSIX timer interface allows for absolute time expiry
+ * values through the TIMER_ABSTIME flag, therefore we have
+ * to synchronize the timer to the clock every time we start it.
+ */
+ thread_group_cputime(tsk, &sum);
+ update_gt_cputime(&cputimer->cputime_atomic, &sum);
+
+ /*
+ * We're setting cputimer->running without a lock. Ensure
+ * this only gets written to in one operation. We set
+ * running after update_gt_cputime() as a small optimization,
+ * but barriers are not required because update_gt_cputime()
+ * can handle concurrent updates.
+ */
+ WRITE_ONCE(cputimer->running, true);
+ }
+ sample_cputime_atomic(times, &cputimer->cputime_atomic);
+}
+
+/*
+ * Sample a process (thread group) clock for the given group_leader task.
+ * Must be called with task sighand lock held for safe while_each_thread()
+ * traversal.
+ */
+static int cpu_clock_sample_group(const clockid_t which_clock,
+ struct task_struct *p,
+ u64 *sample)
+{
+ struct task_cputime cputime;
+
+ switch (CPUCLOCK_WHICH(which_clock)) {
+ default:
+ return -EINVAL;
+ case CPUCLOCK_PROF:
+ thread_group_cputime(p, &cputime);
+ *sample = cputime.utime + cputime.stime;
+ break;
+ case CPUCLOCK_VIRT:
+ thread_group_cputime(p, &cputime);
+ *sample = cputime.utime;
+ break;
+ case CPUCLOCK_SCHED:
+ thread_group_cputime(p, &cputime);
+ *sample = cputime.sum_exec_runtime;
+ break;
+ }
+ return 0;
+}
+
+static int posix_cpu_clock_get_task(struct task_struct *tsk,
+ const clockid_t which_clock,
+ struct timespec64 *tp)
+{
+ int err = -EINVAL;
+ u64 rtn;
+
+ if (CPUCLOCK_PERTHREAD(which_clock)) {
+ if (same_thread_group(tsk, current))
+ err = cpu_clock_sample(which_clock, tsk, &rtn);
+ } else {
+ if (tsk == current || thread_group_leader(tsk))
+ err = cpu_clock_sample_group(which_clock, tsk, &rtn);
+ }
+
+ if (!err)
+ *tp = ns_to_timespec64(rtn);
+
+ return err;
+}
+
+
+static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec64 *tp)
+{
+ const pid_t pid = CPUCLOCK_PID(which_clock);
+ int err = -EINVAL;
+
+ if (pid == 0) {
+ /*
+ * Special case constant value for our own clocks.
+ * We don't have to do any lookup to find ourselves.
+ */
+ err = posix_cpu_clock_get_task(current, which_clock, tp);
+ } else {
+ /*
+ * Find the given PID, and validate that the caller
+ * should be able to see it.
+ */
+ struct task_struct *p;
+ rcu_read_lock();
+ p = find_task_by_vpid(pid);
+ if (p)
+ err = posix_cpu_clock_get_task(p, which_clock, tp);
+ rcu_read_unlock();
+ }
+
+ return err;
+}
+
+/*
+ * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
+ * This is called from sys_timer_create() and do_cpu_nanosleep() with the
+ * new timer already all-zeros initialized.
+ */
+static int posix_cpu_timer_create(struct k_itimer *new_timer)
+{
+ int ret = 0;
+ const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
+ struct task_struct *p;
+
+ if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
+ return -EINVAL;
+
+ new_timer->kclock = &clock_posix_cpu;
+
+ INIT_LIST_HEAD(&new_timer->it.cpu.entry);
+
+ rcu_read_lock();
+ if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
+ if (pid == 0) {
+ p = current;
+ } else {
+ p = find_task_by_vpid(pid);
+ if (p && !same_thread_group(p, current))
+ p = NULL;
+ }
+ } else {
+ if (pid == 0) {
+ p = current->group_leader;
+ } else {
+ p = find_task_by_vpid(pid);
+ if (p && !has_group_leader_pid(p))
+ p = NULL;
+ }
+ }
+ new_timer->it.cpu.task = p;
+ if (p) {
+ get_task_struct(p);
+ } else {
+ ret = -EINVAL;
+ }
+ rcu_read_unlock();
+
+ return ret;
+}
+
+/*
+ * Clean up a CPU-clock timer that is about to be destroyed.
+ * This is called from timer deletion with the timer already locked.
+ * If we return TIMER_RETRY, it's necessary to release the timer's lock
+ * and try again. (This happens when the timer is in the middle of firing.)
+ */
+static int posix_cpu_timer_del(struct k_itimer *timer)
+{
+ int ret = 0;
+ unsigned long flags;
+ struct sighand_struct *sighand;
+ struct task_struct *p = timer->it.cpu.task;
+
+ WARN_ON_ONCE(p == NULL);
+
+ /*
+ * Protect against sighand release/switch in exit/exec and process/
+ * thread timer list entry concurrent read/writes.
+ */
+ sighand = lock_task_sighand(p, &flags);
+ if (unlikely(sighand == NULL)) {
+ /*
+ * We raced with the reaping of the task.
+ * The deletion should have cleared us off the list.
+ */
+ WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry));
+ } else {
+ if (timer->it.cpu.firing)
+ ret = TIMER_RETRY;
+ else
+ list_del(&timer->it.cpu.entry);
+
+ unlock_task_sighand(p, &flags);
+ }
+
+ if (!ret)
+ put_task_struct(p);
+
+ return ret;
+}
+
+static void cleanup_timers_list(struct list_head *head)
+{
+ struct cpu_timer_list *timer, *next;
+
+ list_for_each_entry_safe(timer, next, head, entry)
+ list_del_init(&timer->entry);
+}
+
+/*
+ * Clean out CPU timers still ticking when a thread exited. The task
+ * pointer is cleared, and the expiry time is replaced with the residual
+ * time for later timer_gettime calls to return.
+ * This must be called with the siglock held.
+ */
+static void cleanup_timers(struct list_head *head)
+{
+ cleanup_timers_list(head);
+ cleanup_timers_list(++head);
+ cleanup_timers_list(++head);
+}
+
+/*
+ * These are both called with the siglock held, when the current thread
+ * is being reaped. When the final (leader) thread in the group is reaped,
+ * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
+ */
+void posix_cpu_timers_exit(struct task_struct *tsk)
+{
+ cleanup_timers(tsk->cpu_timers);
+}
+void posix_cpu_timers_exit_group(struct task_struct *tsk)
+{
+ cleanup_timers(tsk->signal->cpu_timers);
+}
+
+static inline int expires_gt(u64 expires, u64 new_exp)
+{
+ return expires == 0 || expires > new_exp;
+}
+
+/*
+ * Insert the timer on the appropriate list before any timers that
+ * expire later. This must be called with the sighand lock held.
+ */
+static void arm_timer(struct k_itimer *timer)
+{
+ struct task_struct *p = timer->it.cpu.task;
+ struct list_head *head, *listpos;
+ struct task_cputime *cputime_expires;
+ struct cpu_timer_list *const nt = &timer->it.cpu;
+ struct cpu_timer_list *next;
+
+ if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
+ head = p->cpu_timers;
+ cputime_expires = &p->cputime_expires;
+ } else {
+ head = p->signal->cpu_timers;
+ cputime_expires = &p->signal->cputime_expires;
+ }
+ head += CPUCLOCK_WHICH(timer->it_clock);
+
+ listpos = head;
+ list_for_each_entry(next, head, entry) {
+ if (nt->expires < next->expires)
+ break;
+ listpos = &next->entry;
+ }
+ list_add(&nt->entry, listpos);
+
+ if (listpos == head) {
+ u64 exp = nt->expires;
+
+ /*
+ * We are the new earliest-expiring POSIX 1.b timer, hence
+ * need to update expiration cache. Take into account that
+ * for process timers we share expiration cache with itimers
+ * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
+ */
+
+ switch (CPUCLOCK_WHICH(timer->it_clock)) {
+ case CPUCLOCK_PROF:
+ if (expires_gt(cputime_expires->prof_exp, exp))
+ cputime_expires->prof_exp = exp;
+ break;
+ case CPUCLOCK_VIRT:
+ if (expires_gt(cputime_expires->virt_exp, exp))
+ cputime_expires->virt_exp = exp;
+ break;
+ case CPUCLOCK_SCHED:
+ if (expires_gt(cputime_expires->sched_exp, exp))
+ cputime_expires->sched_exp = exp;
+ break;
+ }
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
+ tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
+ else
+ tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
+ }
+}
+
+/*
+ * The timer is locked, fire it and arrange for its reload.
+ */
+static void cpu_timer_fire(struct k_itimer *timer)
+{
+ if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
+ /*
+ * User don't want any signal.
+ */
+ timer->it.cpu.expires = 0;
+ } else if (unlikely(timer->sigq == NULL)) {
+ /*
+ * This a special case for clock_nanosleep,
+ * not a normal timer from sys_timer_create.
+ */
+ wake_up_process(timer->it_process);
+ timer->it.cpu.expires = 0;
+ } else if (timer->it.cpu.incr == 0) {
+ /*
+ * One-shot timer. Clear it as soon as it's fired.
+ */
+ posix_timer_event(timer, 0);
+ timer->it.cpu.expires = 0;
+ } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
+ /*
+ * The signal did not get queued because the signal
+ * was ignored, so we won't get any callback to
+ * reload the timer. But we need to keep it
+ * ticking in case the signal is deliverable next time.
+ */
+ posix_cpu_timer_rearm(timer);
+ ++timer->it_requeue_pending;
+ }
+}
+
+/*
+ * Sample a process (thread group) timer for the given group_leader task.
+ * Must be called with task sighand lock held for safe while_each_thread()
+ * traversal.
+ */
+static int cpu_timer_sample_group(const clockid_t which_clock,
+ struct task_struct *p, u64 *sample)
+{
+ struct task_cputime cputime;
+
+ thread_group_cputimer(p, &cputime);
+ switch (CPUCLOCK_WHICH(which_clock)) {
+ default:
+ return -EINVAL;
+ case CPUCLOCK_PROF:
+ *sample = cputime.utime + cputime.stime;
+ break;
+ case CPUCLOCK_VIRT:
+ *sample = cputime.utime;
+ break;
+ case CPUCLOCK_SCHED:
+ *sample = cputime.sum_exec_runtime;
+ break;
+ }
+ return 0;
+}
+
+/*
+ * Guts of sys_timer_settime for CPU timers.
+ * This is called with the timer locked and interrupts disabled.
+ * If we return TIMER_RETRY, it's necessary to release the timer's lock
+ * and try again. (This happens when the timer is in the middle of firing.)
+ */
+static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
+ struct itimerspec64 *new, struct itimerspec64 *old)
+{
+ unsigned long flags;
+ struct sighand_struct *sighand;
+ struct task_struct *p = timer->it.cpu.task;
+ u64 old_expires, new_expires, old_incr, val;
+ int ret;
+
+ WARN_ON_ONCE(p == NULL);
+
+ /*
+ * Use the to_ktime conversion because that clamps the maximum
+ * value to KTIME_MAX and avoid multiplication overflows.
+ */
+ new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value));
+
+ /*
+ * Protect against sighand release/switch in exit/exec and p->cpu_timers
+ * and p->signal->cpu_timers read/write in arm_timer()
+ */
+ sighand = lock_task_sighand(p, &flags);
+ /*
+ * If p has just been reaped, we can no
+ * longer get any information about it at all.
+ */
+ if (unlikely(sighand == NULL)) {
+ return -ESRCH;
+ }
+
+ /*
+ * Disarm any old timer after extracting its expiry time.
+ */
+
+ ret = 0;
+ old_incr = timer->it.cpu.incr;
+ old_expires = timer->it.cpu.expires;
+ if (unlikely(timer->it.cpu.firing)) {
+ timer->it.cpu.firing = -1;
+ ret = TIMER_RETRY;
+ } else
+ list_del_init(&timer->it.cpu.entry);
+
+ /*
+ * We need to sample the current value to convert the new
+ * value from to relative and absolute, and to convert the
+ * old value from absolute to relative. To set a process
+ * timer, we need a sample to balance the thread expiry
+ * times (in arm_timer). With an absolute time, we must
+ * check if it's already passed. In short, we need a sample.
+ */
+ if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
+ cpu_clock_sample(timer->it_clock, p, &val);
+ } else {
+ cpu_timer_sample_group(timer->it_clock, p, &val);
+ }
+
+ if (old) {
+ if (old_expires == 0) {
+ old->it_value.tv_sec = 0;
+ old->it_value.tv_nsec = 0;
+ } else {
+ /*
+ * Update the timer in case it has
+ * overrun already. If it has,
+ * we'll report it as having overrun
+ * and with the next reloaded timer
+ * already ticking, though we are
+ * swallowing that pending
+ * notification here to install the
+ * new setting.
+ */
+ bump_cpu_timer(timer, val);
+ if (val < timer->it.cpu.expires) {
+ old_expires = timer->it.cpu.expires - val;
+ old->it_value = ns_to_timespec64(old_expires);
+ } else {
+ old->it_value.tv_nsec = 1;
+ old->it_value.tv_sec = 0;
+ }
+ }
+ }
+
+ if (unlikely(ret)) {
+ /*
+ * We are colliding with the timer actually firing.
+ * Punt after filling in the timer's old value, and
+ * disable this firing since we are already reporting
+ * it as an overrun (thanks to bump_cpu_timer above).
+ */
+ unlock_task_sighand(p, &flags);
+ goto out;
+ }
+
+ if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) {
+ new_expires += val;
+ }
+
+ /*
+ * Install the new expiry time (or zero).
+ * For a timer with no notification action, we don't actually
+ * arm the timer (we'll just fake it for timer_gettime).
+ */
+ timer->it.cpu.expires = new_expires;
+ if (new_expires != 0 && val < new_expires) {
+ arm_timer(timer);
+ }
+
+ unlock_task_sighand(p, &flags);
+ /*
+ * Install the new reload setting, and
+ * set up the signal and overrun bookkeeping.
+ */
+ timer->it.cpu.incr = timespec64_to_ns(&new->it_interval);
+
+ /*
+ * This acts as a modification timestamp for the timer,
+ * so any automatic reload attempt will punt on seeing
+ * that we have reset the timer manually.
+ */
+ timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
+ ~REQUEUE_PENDING;
+ timer->it_overrun_last = 0;
+ timer->it_overrun = -1;
+
+ if (new_expires != 0 && !(val < new_expires)) {
+ /*
+ * The designated time already passed, so we notify
+ * immediately, even if the thread never runs to
+ * accumulate more time on this clock.
+ */
+ cpu_timer_fire(timer);
+ }
+
+ ret = 0;
+ out:
+ if (old)
+ old->it_interval = ns_to_timespec64(old_incr);
+
+ return ret;
+}
+
+static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
+{
+ u64 now;
+ struct task_struct *p = timer->it.cpu.task;
+
+ WARN_ON_ONCE(p == NULL);
+
+ /*
+ * Easy part: convert the reload time.
+ */
+ itp->it_interval = ns_to_timespec64(timer->it.cpu.incr);
+
+ if (!timer->it.cpu.expires)
+ return;
+
+ /*
+ * Sample the clock to take the difference with the expiry time.
+ */
+ if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
+ cpu_clock_sample(timer->it_clock, p, &now);
+ } else {
+ struct sighand_struct *sighand;
+ unsigned long flags;
+
+ /*
+ * Protect against sighand release/switch in exit/exec and
+ * also make timer sampling safe if it ends up calling
+ * thread_group_cputime().
+ */
+ sighand = lock_task_sighand(p, &flags);
+ if (unlikely(sighand == NULL)) {
+ /*
+ * The process has been reaped.
+ * We can't even collect a sample any more.
+ * Call the timer disarmed, nothing else to do.
+ */
+ timer->it.cpu.expires = 0;
+ return;
+ } else {
+ cpu_timer_sample_group(timer->it_clock, p, &now);
+ unlock_task_sighand(p, &flags);
+ }
+ }
+
+ if (now < timer->it.cpu.expires) {
+ itp->it_value = ns_to_timespec64(timer->it.cpu.expires - now);
+ } else {
+ /*
+ * The timer should have expired already, but the firing
+ * hasn't taken place yet. Say it's just about to expire.
+ */
+ itp->it_value.tv_nsec = 1;
+ itp->it_value.tv_sec = 0;
+ }
+}
+
+static unsigned long long
+check_timers_list(struct list_head *timers,
+ struct list_head *firing,
+ unsigned long long curr)
+{
+ int maxfire = 20;
+
+ while (!list_empty(timers)) {
+ struct cpu_timer_list *t;
+
+ t = list_first_entry(timers, struct cpu_timer_list, entry);
+
+ if (!--maxfire || curr < t->expires)
+ return t->expires;
+
+ t->firing = 1;
+ list_move_tail(&t->entry, firing);
+ }
+
+ return 0;
+}
+
+static inline void check_dl_overrun(struct task_struct *tsk)
+{
+ if (tsk->dl.dl_overrun) {
+ tsk->dl.dl_overrun = 0;
+ __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
+ }
+}
+
+/*
+ * Check for any per-thread CPU timers that have fired and move them off
+ * the tsk->cpu_timers[N] list onto the firing list. Here we update the
+ * tsk->it_*_expires values to reflect the remaining thread CPU timers.
+ */
+static void check_thread_timers(struct task_struct *tsk,
+ struct list_head *firing)
+{
+ struct list_head *timers = tsk->cpu_timers;
+ struct task_cputime *tsk_expires = &tsk->cputime_expires;
+ u64 expires;
+ unsigned long soft;
+
+ if (dl_task(tsk))
+ check_dl_overrun(tsk);
+
+ /*
+ * If cputime_expires is zero, then there are no active
+ * per thread CPU timers.
+ */
+ if (task_cputime_zero(&tsk->cputime_expires))
+ return;
+
+ expires = check_timers_list(timers, firing, prof_ticks(tsk));
+ tsk_expires->prof_exp = expires;
+
+ expires = check_timers_list(++timers, firing, virt_ticks(tsk));
+ tsk_expires->virt_exp = expires;
+
+ tsk_expires->sched_exp = check_timers_list(++timers, firing,
+ tsk->se.sum_exec_runtime);
+
+ /*
+ * Check for the special case thread timers.
+ */
+ soft = task_rlimit(tsk, RLIMIT_RTTIME);
+ if (soft != RLIM_INFINITY) {
+ unsigned long hard = task_rlimit_max(tsk, RLIMIT_RTTIME);
+
+ if (hard != RLIM_INFINITY &&
+ tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
+ /*
+ * At the hard limit, we just die.
+ * No need to calculate anything else now.
+ */
+ if (print_fatal_signals) {
+ pr_info("CPU Watchdog Timeout (hard): %s[%d]\n",
+ tsk->comm, task_pid_nr(tsk));
+ }
+ __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
+ return;
+ }
+ if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
+ /*
+ * At the soft limit, send a SIGXCPU every second.
+ */
+ if (soft < hard) {
+ soft += USEC_PER_SEC;
+ tsk->signal->rlim[RLIMIT_RTTIME].rlim_cur =
+ soft;
+ }
+ if (print_fatal_signals) {
+ pr_info("RT Watchdog Timeout (soft): %s[%d]\n",
+ tsk->comm, task_pid_nr(tsk));
+ }
+ __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
+ }
+ }
+ if (task_cputime_zero(tsk_expires))
+ tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
+}
+
+static inline void stop_process_timers(struct signal_struct *sig)
+{
+ struct thread_group_cputimer *cputimer = &sig->cputimer;
+
+ /* Turn off cputimer->running. This is done without locking. */
+ WRITE_ONCE(cputimer->running, false);
+ tick_dep_clear_signal(sig, TICK_DEP_BIT_POSIX_TIMER);
+}
+
+static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
+ u64 *expires, u64 cur_time, int signo)
+{
+ if (!it->expires)
+ return;
+
+ if (cur_time >= it->expires) {
+ if (it->incr)
+ it->expires += it->incr;
+ else
+ it->expires = 0;
+
+ trace_itimer_expire(signo == SIGPROF ?
+ ITIMER_PROF : ITIMER_VIRTUAL,
+ task_tgid(tsk), cur_time);
+ __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
+ }
+
+ if (it->expires && (!*expires || it->expires < *expires))
+ *expires = it->expires;
+}
+
+/*
+ * Check for any per-thread CPU timers that have fired and move them
+ * off the tsk->*_timers list onto the firing list. Per-thread timers
+ * have already been taken off.
+ */
+static void check_process_timers(struct task_struct *tsk,
+ struct list_head *firing)
+{
+ struct signal_struct *const sig = tsk->signal;
+ u64 utime, ptime, virt_expires, prof_expires;
+ u64 sum_sched_runtime, sched_expires;
+ struct list_head *timers = sig->cpu_timers;
+ struct task_cputime cputime;
+ unsigned long soft;
+
+ if (dl_task(tsk))
+ check_dl_overrun(tsk);
+
+ /*
+ * If cputimer is not running, then there are no active
+ * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU).
+ */
+ if (!READ_ONCE(tsk->signal->cputimer.running))
+ return;
+
+ /*
+ * Signify that a thread is checking for process timers.
+ * Write access to this field is protected by the sighand lock.
+ */
+ sig->cputimer.checking_timer = true;
+
+ /*
+ * Collect the current process totals.
+ */
+ thread_group_cputimer(tsk, &cputime);
+ utime = cputime.utime;
+ ptime = utime + cputime.stime;
+ sum_sched_runtime = cputime.sum_exec_runtime;
+
+ prof_expires = check_timers_list(timers, firing, ptime);
+ virt_expires = check_timers_list(++timers, firing, utime);
+ sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);
+
+ /*
+ * Check for the special case process timers.
+ */
+ check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
+ SIGPROF);
+ check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
+ SIGVTALRM);
+ soft = task_rlimit(tsk, RLIMIT_CPU);
+ if (soft != RLIM_INFINITY) {
+ unsigned long psecs = div_u64(ptime, NSEC_PER_SEC);
+ unsigned long hard = task_rlimit_max(tsk, RLIMIT_CPU);
+ u64 x;
+ if (psecs >= hard) {
+ /*
+ * At the hard limit, we just die.
+ * No need to calculate anything else now.
+ */
+ if (print_fatal_signals) {
+ pr_info("RT Watchdog Timeout (hard): %s[%d]\n",
+ tsk->comm, task_pid_nr(tsk));
+ }
+ __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
+ return;
+ }
+ if (psecs >= soft) {
+ /*
+ * At the soft limit, send a SIGXCPU every second.
+ */
+ if (print_fatal_signals) {
+ pr_info("CPU Watchdog Timeout (soft): %s[%d]\n",
+ tsk->comm, task_pid_nr(tsk));
+ }
+ __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
+ if (soft < hard) {
+ soft++;
+ sig->rlim[RLIMIT_CPU].rlim_cur = soft;
+ }
+ }
+ x = soft * NSEC_PER_SEC;
+ if (!prof_expires || x < prof_expires)
+ prof_expires = x;
+ }
+
+ sig->cputime_expires.prof_exp = prof_expires;
+ sig->cputime_expires.virt_exp = virt_expires;
+ sig->cputime_expires.sched_exp = sched_expires;
+ if (task_cputime_zero(&sig->cputime_expires))
+ stop_process_timers(sig);
+
+ sig->cputimer.checking_timer = false;
+}
+
+/*
+ * This is called from the signal code (via posixtimer_rearm)
+ * when the last timer signal was delivered and we have to reload the timer.
+ */
+static void posix_cpu_timer_rearm(struct k_itimer *timer)
+{
+ struct sighand_struct *sighand;
+ unsigned long flags;
+ struct task_struct *p = timer->it.cpu.task;
+ u64 now;
+
+ WARN_ON_ONCE(p == NULL);
+
+ /*
+ * Fetch the current sample and update the timer's expiry time.
+ */
+ if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
+ cpu_clock_sample(timer->it_clock, p, &now);
+ bump_cpu_timer(timer, now);
+ if (unlikely(p->exit_state))
+ return;
+
+ /* Protect timer list r/w in arm_timer() */
+ sighand = lock_task_sighand(p, &flags);
+ if (!sighand)
+ return;
+ } else {
+ /*
+ * Protect arm_timer() and timer sampling in case of call to
+ * thread_group_cputime().
+ */
+ sighand = lock_task_sighand(p, &flags);
+ if (unlikely(sighand == NULL)) {
+ /*
+ * The process has been reaped.
+ * We can't even collect a sample any more.
+ */
+ timer->it.cpu.expires = 0;
+ return;
+ } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
+ /* If the process is dying, no need to rearm */
+ goto unlock;
+ }
+ cpu_timer_sample_group(timer->it_clock, p, &now);
+ bump_cpu_timer(timer, now);
+ /* Leave the sighand locked for the call below. */
+ }
+
+ /*
+ * Now re-arm for the new expiry time.
+ */
+ arm_timer(timer);
+unlock:
+ unlock_task_sighand(p, &flags);
+}
+
+/**
+ * task_cputime_expired - Compare two task_cputime entities.
+ *
+ * @sample: The task_cputime structure to be checked for expiration.
+ * @expires: Expiration times, against which @sample will be checked.
+ *
+ * Checks @sample against @expires to see if any field of @sample has expired.
+ * Returns true if any field of the former is greater than the corresponding
+ * field of the latter if the latter field is set. Otherwise returns false.
+ */
+static inline int task_cputime_expired(const struct task_cputime *sample,
+ const struct task_cputime *expires)
+{
+ if (expires->utime && sample->utime >= expires->utime)
+ return 1;
+ if (expires->stime && sample->utime + sample->stime >= expires->stime)
+ return 1;
+ if (expires->sum_exec_runtime != 0 &&
+ sample->sum_exec_runtime >= expires->sum_exec_runtime)
+ return 1;
+ return 0;
+}
+
+/**
+ * fastpath_timer_check - POSIX CPU timers fast path.
+ *
+ * @tsk: The task (thread) being checked.
+ *
+ * Check the task and thread group timers. If both are zero (there are no
+ * timers set) return false. Otherwise snapshot the task and thread group
+ * timers and compare them with the corresponding expiration times. Return
+ * true if a timer has expired, else return false.
+ */
+static inline int fastpath_timer_check(struct task_struct *tsk)
+{
+ struct signal_struct *sig;
+
+ if (!task_cputime_zero(&tsk->cputime_expires)) {
+ struct task_cputime task_sample;
+
+ task_cputime(tsk, &task_sample.utime, &task_sample.stime);
+ task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
+ if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
+ return 1;
+ }
+
+ sig = tsk->signal;
+ /*
+ * Check if thread group timers expired when the cputimer is
+ * running and no other thread in the group is already checking
+ * for thread group cputimers. These fields are read without the
+ * sighand lock. However, this is fine because this is meant to
+ * be a fastpath heuristic to determine whether we should try to
+ * acquire the sighand lock to check/handle timers.
+ *
+ * In the worst case scenario, if 'running' or 'checking_timer' gets
+ * set but the current thread doesn't see the change yet, we'll wait
+ * until the next thread in the group gets a scheduler interrupt to
+ * handle the timer. This isn't an issue in practice because these
+ * types of delays with signals actually getting sent are expected.
+ */
+ if (READ_ONCE(sig->cputimer.running) &&
+ !READ_ONCE(sig->cputimer.checking_timer)) {
+ struct task_cputime group_sample;
+
+ sample_cputime_atomic(&group_sample, &sig->cputimer.cputime_atomic);
+
+ if (task_cputime_expired(&group_sample, &sig->cputime_expires))
+ return 1;
+ }
+
+ if (dl_task(tsk) && tsk->dl.dl_overrun)
+ return 1;
+
+ return 0;
+}
+
+/*
+ * This is called from the timer interrupt handler. The irq handler has
+ * already updated our counts. We need to check if any timers fire now.
+ * Interrupts are disabled.
+ */
+void run_posix_cpu_timers(struct task_struct *tsk)
+{
+ LIST_HEAD(firing);
+ struct k_itimer *timer, *next;
+ unsigned long flags;
+
+ lockdep_assert_irqs_disabled();
+
+ /*
+ * The fast path checks that there are no expired thread or thread
+ * group timers. If that's so, just return.
+ */
+ if (!fastpath_timer_check(tsk))
+ return;
+
+ if (!lock_task_sighand(tsk, &flags))
+ return;
+ /*
+ * Here we take off tsk->signal->cpu_timers[N] and
+ * tsk->cpu_timers[N] all the timers that are firing, and
+ * put them on the firing list.
+ */
+ check_thread_timers(tsk, &firing);
+
+ check_process_timers(tsk, &firing);
+
+ /*
+ * We must release these locks before taking any timer's lock.
+ * There is a potential race with timer deletion here, as the
+ * siglock now protects our private firing list. We have set
+ * the firing flag in each timer, so that a deletion attempt
+ * that gets the timer lock before we do will give it up and
+ * spin until we've taken care of that timer below.
+ */
+ unlock_task_sighand(tsk, &flags);
+
+ /*
+ * Now that all the timers on our list have the firing flag,
+ * no one will touch their list entries but us. We'll take
+ * each timer's lock before clearing its firing flag, so no
+ * timer call will interfere.
+ */
+ list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
+ int cpu_firing;
+
+ spin_lock(&timer->it_lock);
+ list_del_init(&timer->it.cpu.entry);
+ cpu_firing = timer->it.cpu.firing;
+ timer->it.cpu.firing = 0;
+ /*
+ * The firing flag is -1 if we collided with a reset
+ * of the timer, which already reported this
+ * almost-firing as an overrun. So don't generate an event.
+ */
+ if (likely(cpu_firing >= 0))
+ cpu_timer_fire(timer);
+ spin_unlock(&timer->it_lock);
+ }
+}
+
+/*
+ * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
+ * The tsk->sighand->siglock must be held by the caller.
+ */
+void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
+ u64 *newval, u64 *oldval)
+{
+ u64 now;
+ int ret;
+
+ WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED);
+ ret = cpu_timer_sample_group(clock_idx, tsk, &now);
+
+ if (oldval && ret != -EINVAL) {
+ /*
+ * We are setting itimer. The *oldval is absolute and we update
+ * it to be relative, *newval argument is relative and we update
+ * it to be absolute.
+ */
+ if (*oldval) {
+ if (*oldval <= now) {
+ /* Just about to fire. */
+ *oldval = TICK_NSEC;
+ } else {
+ *oldval -= now;
+ }
+ }
+
+ if (!*newval)
+ return;
+ *newval += now;
+ }
+
+ /*
+ * Update expiration cache if we are the earliest timer, or eventually
+ * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
+ */
+ switch (clock_idx) {
+ case CPUCLOCK_PROF:
+ if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
+ tsk->signal->cputime_expires.prof_exp = *newval;
+ break;
+ case CPUCLOCK_VIRT:
+ if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
+ tsk->signal->cputime_expires.virt_exp = *newval;
+ break;
+ }
+
+ tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER);
+}
+
+static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
+ const struct timespec64 *rqtp)
+{
+ struct itimerspec64 it;
+ struct k_itimer timer;
+ u64 expires;
+ int error;
+
+ /*
+ * Set up a temporary timer and then wait for it to go off.
+ */
+ memset(&timer, 0, sizeof timer);
+ spin_lock_init(&timer.it_lock);
+ timer.it_clock = which_clock;
+ timer.it_overrun = -1;
+ error = posix_cpu_timer_create(&timer);
+ timer.it_process = current;
+ if (!error) {
+ static struct itimerspec64 zero_it;
+ struct restart_block *restart;
+
+ memset(&it, 0, sizeof(it));
+ it.it_value = *rqtp;
+
+ spin_lock_irq(&timer.it_lock);
+ error = posix_cpu_timer_set(&timer, flags, &it, NULL);
+ if (error) {
+ spin_unlock_irq(&timer.it_lock);
+ return error;
+ }
+
+ while (!signal_pending(current)) {
+ if (timer.it.cpu.expires == 0) {
+ /*
+ * Our timer fired and was reset, below
+ * deletion can not fail.
+ */
+ posix_cpu_timer_del(&timer);
+ spin_unlock_irq(&timer.it_lock);
+ return 0;
+ }
+
+ /*
+ * Block until cpu_timer_fire (or a signal) wakes us.
+ */
+ __set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irq(&timer.it_lock);
+ schedule();
+ spin_lock_irq(&timer.it_lock);
+ }
+
+ /*
+ * We were interrupted by a signal.
+ */
+ expires = timer.it.cpu.expires;
+ error = posix_cpu_timer_set(&timer, 0, &zero_it, &it);
+ if (!error) {
+ /*
+ * Timer is now unarmed, deletion can not fail.
+ */
+ posix_cpu_timer_del(&timer);
+ }
+ spin_unlock_irq(&timer.it_lock);
+
+ while (error == TIMER_RETRY) {
+ /*
+ * We need to handle case when timer was or is in the
+ * middle of firing. In other cases we already freed
+ * resources.
+ */
+ spin_lock_irq(&timer.it_lock);
+ error = posix_cpu_timer_del(&timer);
+ spin_unlock_irq(&timer.it_lock);
+ }
+
+ if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
+ /*
+ * It actually did fire already.
+ */
+ return 0;
+ }
+
+ error = -ERESTART_RESTARTBLOCK;
+ /*
+ * Report back to the user the time still remaining.
+ */
+ restart = ¤t->restart_block;
+ restart->nanosleep.expires = expires;
+ if (restart->nanosleep.type != TT_NONE)
+ error = nanosleep_copyout(restart, &it.it_value);
+ }
+
+ return error;
+}
+
+static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
+
+static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
+ const struct timespec64 *rqtp)
+{
+ struct restart_block *restart_block = ¤t->restart_block;
+ int error;
+
+ /*
+ * Diagnose required errors first.
+ */
+ if (CPUCLOCK_PERTHREAD(which_clock) &&
+ (CPUCLOCK_PID(which_clock) == 0 ||
+ CPUCLOCK_PID(which_clock) == task_pid_vnr(current)))
+ return -EINVAL;
+
+ error = do_cpu_nanosleep(which_clock, flags, rqtp);
+
+ if (error == -ERESTART_RESTARTBLOCK) {
+
+ if (flags & TIMER_ABSTIME)
+ return -ERESTARTNOHAND;
+
+ restart_block->fn = posix_cpu_nsleep_restart;
+ restart_block->nanosleep.clockid = which_clock;
+ }
+ return error;
+}
+
+static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
+{
+ clockid_t which_clock = restart_block->nanosleep.clockid;
+ struct timespec64 t;
+
+ t = ns_to_timespec64(restart_block->nanosleep.expires);
+
+ return do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t);
+}
+
+#define PROCESS_CLOCK make_process_cpuclock(0, CPUCLOCK_SCHED)
+#define THREAD_CLOCK make_thread_cpuclock(0, CPUCLOCK_SCHED)
+
+static int process_cpu_clock_getres(const clockid_t which_clock,
+ struct timespec64 *tp)
+{
+ return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
+}
+static int process_cpu_clock_get(const clockid_t which_clock,
+ struct timespec64 *tp)
+{
+ return posix_cpu_clock_get(PROCESS_CLOCK, tp);
+}
+static int process_cpu_timer_create(struct k_itimer *timer)
+{
+ timer->it_clock = PROCESS_CLOCK;
+ return posix_cpu_timer_create(timer);
+}
+static int process_cpu_nsleep(const clockid_t which_clock, int flags,
+ const struct timespec64 *rqtp)
+{
+ return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp);
+}
+static int thread_cpu_clock_getres(const clockid_t which_clock,
+ struct timespec64 *tp)
+{
+ return posix_cpu_clock_getres(THREAD_CLOCK, tp);
+}
+static int thread_cpu_clock_get(const clockid_t which_clock,
+ struct timespec64 *tp)
+{
+ return posix_cpu_clock_get(THREAD_CLOCK, tp);
+}
+static int thread_cpu_timer_create(struct k_itimer *timer)
+{
+ timer->it_clock = THREAD_CLOCK;
+ return posix_cpu_timer_create(timer);
+}
+
+const struct k_clock clock_posix_cpu = {
+ .clock_getres = posix_cpu_clock_getres,
+ .clock_set = posix_cpu_clock_set,
+ .clock_get = posix_cpu_clock_get,
+ .timer_create = posix_cpu_timer_create,
+ .nsleep = posix_cpu_nsleep,
+ .timer_set = posix_cpu_timer_set,
+ .timer_del = posix_cpu_timer_del,
+ .timer_get = posix_cpu_timer_get,
+ .timer_rearm = posix_cpu_timer_rearm,
+};
+
+const struct k_clock clock_process = {
+ .clock_getres = process_cpu_clock_getres,
+ .clock_get = process_cpu_clock_get,
+ .timer_create = process_cpu_timer_create,
+ .nsleep = process_cpu_nsleep,
+};
+
+const struct k_clock clock_thread = {
+ .clock_getres = thread_cpu_clock_getres,
+ .clock_get = thread_cpu_clock_get,
+ .timer_create = thread_cpu_timer_create,
+};