// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1992 Darren Senn
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*/
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/* These are all the functions necessary to implement itimers */
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <linux/syscalls.h>
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#include <linux/time.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/cputime.h>
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#include <linux/posix-timers.h>
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#include <linux/hrtimer.h>
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#include <trace/events/timer.h>
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#include <linux/compat.h>
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#include <linux/uaccess.h>
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/**
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* itimer_get_remtime - get remaining time for the timer
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*
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* @timer: the timer to read
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*
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* Returns the delta between the expiry time and now, which can be
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* less than zero or 1usec for an pending expired timer
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*/
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static struct timespec64 itimer_get_remtime(struct hrtimer *timer)
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{
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ktime_t rem = __hrtimer_get_remaining(timer, true);
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/*
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* Racy but safe: if the itimer expires after the above
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* hrtimer_get_remtime() call but before this condition
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* then we return 0 - which is correct.
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*/
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if (hrtimer_active(timer)) {
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if (rem <= 0)
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rem = NSEC_PER_USEC;
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} else
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rem = 0;
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return ktime_to_timespec64(rem);
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}
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static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
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struct itimerspec64 *const value)
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{
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u64 val, interval;
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struct cpu_itimer *it = &tsk->signal->it[clock_id];
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spin_lock_irq(&tsk->sighand->siglock);
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val = it->expires;
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interval = it->incr;
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if (val) {
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u64 t, samples[CPUCLOCK_MAX];
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thread_group_sample_cputime(tsk, samples);
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t = samples[clock_id];
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if (val < t)
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/* about to fire */
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val = TICK_NSEC;
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else
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val -= t;
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}
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spin_unlock_irq(&tsk->sighand->siglock);
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value->it_value = ns_to_timespec64(val);
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value->it_interval = ns_to_timespec64(interval);
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}
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static int do_getitimer(int which, struct itimerspec64 *value)
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{
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struct task_struct *tsk = current;
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switch (which) {
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case ITIMER_REAL:
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spin_lock_irq(&tsk->sighand->siglock);
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value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
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value->it_interval =
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ktime_to_timespec64(tsk->signal->it_real_incr);
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spin_unlock_irq(&tsk->sighand->siglock);
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break;
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case ITIMER_VIRTUAL:
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get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
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break;
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case ITIMER_PROF:
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get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
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break;
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default:
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return(-EINVAL);
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}
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return 0;
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}
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static int put_itimerval(struct __kernel_old_itimerval __user *o,
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const struct itimerspec64 *i)
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{
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struct __kernel_old_itimerval v;
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v.it_interval.tv_sec = i->it_interval.tv_sec;
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v.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
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v.it_value.tv_sec = i->it_value.tv_sec;
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v.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
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return copy_to_user(o, &v, sizeof(struct __kernel_old_itimerval)) ? -EFAULT : 0;
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}
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SYSCALL_DEFINE2(getitimer, int, which, struct __kernel_old_itimerval __user *, value)
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{
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struct itimerspec64 get_buffer;
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int error = do_getitimer(which, &get_buffer);
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if (!error && put_itimerval(value, &get_buffer))
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error = -EFAULT;
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return error;
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}
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#if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
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struct old_itimerval32 {
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struct old_timeval32 it_interval;
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struct old_timeval32 it_value;
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};
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static int put_old_itimerval32(struct old_itimerval32 __user *o,
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const struct itimerspec64 *i)
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{
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struct old_itimerval32 v32;
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v32.it_interval.tv_sec = i->it_interval.tv_sec;
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v32.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
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v32.it_value.tv_sec = i->it_value.tv_sec;
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v32.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
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return copy_to_user(o, &v32, sizeof(struct old_itimerval32)) ? -EFAULT : 0;
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}
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COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
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struct old_itimerval32 __user *, value)
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{
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struct itimerspec64 get_buffer;
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int error = do_getitimer(which, &get_buffer);
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if (!error && put_old_itimerval32(value, &get_buffer))
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error = -EFAULT;
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return error;
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}
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#endif
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/*
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* The timer is automagically restarted, when interval != 0
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*/
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enum hrtimer_restart it_real_fn(struct hrtimer *timer)
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{
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struct signal_struct *sig =
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container_of(timer, struct signal_struct, real_timer);
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struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
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trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
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kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
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return HRTIMER_NORESTART;
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}
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static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
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const struct itimerspec64 *const value,
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struct itimerspec64 *const ovalue)
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{
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u64 oval, nval, ointerval, ninterval;
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struct cpu_itimer *it = &tsk->signal->it[clock_id];
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nval = timespec64_to_ns(&value->it_value);
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ninterval = timespec64_to_ns(&value->it_interval);
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spin_lock_irq(&tsk->sighand->siglock);
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oval = it->expires;
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ointerval = it->incr;
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if (oval || nval) {
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if (nval > 0)
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nval += TICK_NSEC;
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set_process_cpu_timer(tsk, clock_id, &nval, &oval);
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}
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it->expires = nval;
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it->incr = ninterval;
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trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
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ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
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spin_unlock_irq(&tsk->sighand->siglock);
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if (ovalue) {
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ovalue->it_value = ns_to_timespec64(oval);
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ovalue->it_interval = ns_to_timespec64(ointerval);
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}
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}
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/*
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* Returns true if the timeval is in canonical form
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*/
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#define timeval_valid(t) \
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(((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
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static int do_setitimer(int which, struct itimerspec64 *value,
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struct itimerspec64 *ovalue)
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{
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struct task_struct *tsk = current;
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struct hrtimer *timer;
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ktime_t expires;
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switch (which) {
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case ITIMER_REAL:
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again:
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spin_lock_irq(&tsk->sighand->siglock);
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timer = &tsk->signal->real_timer;
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if (ovalue) {
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ovalue->it_value = itimer_get_remtime(timer);
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ovalue->it_interval
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= ktime_to_timespec64(tsk->signal->it_real_incr);
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}
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/* We are sharing ->siglock with it_real_fn() */
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if (hrtimer_try_to_cancel(timer) < 0) {
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spin_unlock_irq(&tsk->sighand->siglock);
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hrtimer_cancel_wait_running(timer);
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goto again;
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}
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expires = timespec64_to_ktime(value->it_value);
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if (expires != 0) {
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tsk->signal->it_real_incr =
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timespec64_to_ktime(value->it_interval);
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hrtimer_start(timer, expires, HRTIMER_MODE_REL);
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} else
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tsk->signal->it_real_incr = 0;
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trace_itimer_state(ITIMER_REAL, value, 0);
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spin_unlock_irq(&tsk->sighand->siglock);
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break;
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case ITIMER_VIRTUAL:
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set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
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break;
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case ITIMER_PROF:
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set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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#ifdef CONFIG_SECURITY_SELINUX
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void clear_itimer(void)
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{
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struct itimerspec64 v = {};
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int i;
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for (i = 0; i < 3; i++)
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do_setitimer(i, &v, NULL);
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}
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#endif
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#ifdef __ARCH_WANT_SYS_ALARM
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/**
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* alarm_setitimer - set alarm in seconds
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*
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* @seconds: number of seconds until alarm
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* 0 disables the alarm
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*
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* Returns the remaining time in seconds of a pending timer or 0 when
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* the timer is not active.
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*
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* On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
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* negative timeval settings which would cause immediate expiry.
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*/
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static unsigned int alarm_setitimer(unsigned int seconds)
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{
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struct itimerspec64 it_new, it_old;
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#if BITS_PER_LONG < 64
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if (seconds > INT_MAX)
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seconds = INT_MAX;
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#endif
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it_new.it_value.tv_sec = seconds;
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it_new.it_value.tv_nsec = 0;
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it_new.it_interval.tv_sec = it_new.it_interval.tv_nsec = 0;
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do_setitimer(ITIMER_REAL, &it_new, &it_old);
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/*
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* We can't return 0 if we have an alarm pending ... And we'd
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* better return too much than too little anyway
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*/
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if ((!it_old.it_value.tv_sec && it_old.it_value.tv_nsec) ||
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it_old.it_value.tv_nsec >= (NSEC_PER_SEC / 2))
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it_old.it_value.tv_sec++;
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return it_old.it_value.tv_sec;
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}
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/*
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* For backwards compatibility? This can be done in libc so Alpha
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* and all newer ports shouldn't need it.
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*/
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SYSCALL_DEFINE1(alarm, unsigned int, seconds)
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{
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return alarm_setitimer(seconds);
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}
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#endif
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static int get_itimerval(struct itimerspec64 *o, const struct __kernel_old_itimerval __user *i)
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{
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struct __kernel_old_itimerval v;
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if (copy_from_user(&v, i, sizeof(struct __kernel_old_itimerval)))
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return -EFAULT;
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/* Validate the timevals in value. */
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if (!timeval_valid(&v.it_value) ||
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!timeval_valid(&v.it_interval))
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return -EINVAL;
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o->it_interval.tv_sec = v.it_interval.tv_sec;
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o->it_interval.tv_nsec = v.it_interval.tv_usec * NSEC_PER_USEC;
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o->it_value.tv_sec = v.it_value.tv_sec;
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o->it_value.tv_nsec = v.it_value.tv_usec * NSEC_PER_USEC;
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return 0;
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}
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SYSCALL_DEFINE3(setitimer, int, which, struct __kernel_old_itimerval __user *, value,
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struct __kernel_old_itimerval __user *, ovalue)
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{
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struct itimerspec64 set_buffer, get_buffer;
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int error;
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if (value) {
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error = get_itimerval(&set_buffer, value);
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if (error)
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return error;
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} else {
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memset(&set_buffer, 0, sizeof(set_buffer));
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printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
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" Misfeature support will be removed\n",
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current->comm);
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}
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error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
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if (error || !ovalue)
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return error;
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if (put_itimerval(ovalue, &get_buffer))
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return -EFAULT;
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return 0;
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}
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#if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
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static int get_old_itimerval32(struct itimerspec64 *o, const struct old_itimerval32 __user *i)
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{
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struct old_itimerval32 v32;
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if (copy_from_user(&v32, i, sizeof(struct old_itimerval32)))
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return -EFAULT;
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/* Validate the timevals in value. */
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if (!timeval_valid(&v32.it_value) ||
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!timeval_valid(&v32.it_interval))
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return -EINVAL;
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o->it_interval.tv_sec = v32.it_interval.tv_sec;
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o->it_interval.tv_nsec = v32.it_interval.tv_usec * NSEC_PER_USEC;
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o->it_value.tv_sec = v32.it_value.tv_sec;
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o->it_value.tv_nsec = v32.it_value.tv_usec * NSEC_PER_USEC;
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return 0;
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}
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COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
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struct old_itimerval32 __user *, value,
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struct old_itimerval32 __user *, ovalue)
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{
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struct itimerspec64 set_buffer, get_buffer;
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int error;
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if (value) {
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error = get_old_itimerval32(&set_buffer, value);
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if (error)
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return error;
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} else {
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memset(&set_buffer, 0, sizeof(set_buffer));
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printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
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" Misfeature support will be removed\n",
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current->comm);
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}
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error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
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if (error || !ovalue)
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return error;
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if (put_old_itimerval32(ovalue, &get_buffer))
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return -EFAULT;
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return 0;
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}
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#endif
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