/*

 * linux/kernel/itimer.c

 *

 * Copyright (C) 1992 Darren Senn

 */

/* These are all the functions necessary to implement itimers */

#include <linux/mm.h>

#include <linux/interrupt.h>

#include <linux/syscalls.h>

#include <linux/time.h>

#include <linux/posix-timers.h>

#include <linux/hrtimer.h>

#include <asm/uaccess.h>

/**

 * itimer_get_remtime - get remaining time for the timer

 *

 * @timer: the timer to read

 *

 * Returns the delta between the expiry time and now, which can be

 * less than zero or 1usec for an pending expired timer

 */

static struct timeval itimer_get_remtime(struct hrtimer *timer)

{

	ktime_t rem = hrtimer_get_remaining(timer);

	/*

	 * Racy but safe: if the itimer expires after the above

	 * hrtimer_get_remtime() call but before this condition

	 * then we return 0 - which is correct.

	 */

	if (hrtimer_active(timer)) {

		if (rem.tv64 <= 0)

			rem.tv64 = NSEC_PER_USEC;

	} else

		rem.tv64 = 0;

	return ktime_to_timeval(rem);

}

int do_getitimer(int which, struct itimerval *value)

{

	struct task_struct *tsk = current;

	cputime_t cinterval, cval;

	switch (which) {

	case ITIMER_REAL:

		spin_lock_irq(&tsk->sighand->siglock);

		value->it_value = itimer_get_remtime(&tsk->signal->real_timer);

		value->it_interval =

			ktime_to_timeval(tsk->signal->it_real_incr);

		spin_unlock_irq(&tsk->sighand->siglock);

		break;

	case ITIMER_VIRTUAL:

		spin_lock_irq(&tsk->sighand->siglock);

		cval = tsk->signal->it_virt_expires;

		cinterval = tsk->signal->it_virt_incr;

		if (!cputime_eq(cval, cputime_zero)) {

			struct task_cputime cputime;

			cputime_t utime;

			utime = cputime.utime;

			if (cputime_le(cval, utime)) { /* about to fire */

				cval = jiffies_to_cputime(1);

			} else {

				cval = cputime_sub(cval, utime);

			}

		}

		spin_unlock_irq(&tsk->sighand->siglock);

		cputime_to_timeval(cval, &value->it_value);

		cputime_to_timeval(cinterval, &value->it_interval);

		break;

	case ITIMER_PROF:

		spin_lock_irq(&tsk->sighand->siglock);

		cval = tsk->signal->it_prof_expires;

		cinterval = tsk->signal->it_prof_incr;

		if (!cputime_eq(cval, cputime_zero)) {

			struct task_cputime times;

			cputime_t ptime;

			ptime = cputime_add(times.utime, times.stime);

			if (cputime_le(cval, ptime)) { /* about to fire */

				cval = jiffies_to_cputime(1);

			} else {

				cval = cputime_sub(cval, ptime);

			}

		}

		spin_unlock_irq(&tsk->sighand->siglock);

		cputime_to_timeval(cval, &value->it_value);

		cputime_to_timeval(cinterval, &value->it_interval);

		break;

	default:

		return(-EINVAL);

	}

	return 0;

}

{

	int error = -EFAULT;

	struct itimerval get_buffer;

	if (value) {

		error = do_getitimer(which, &get_buffer);

		if (!error &&

		    copy_to_user(value, &get_buffer, sizeof(get_buffer)))

			error = -EFAULT;

	}

	return error;

}

/*

 * The timer is automagically restarted, when interval != 0

 */

enum hrtimer_restart it_real_fn(struct hrtimer *timer)

{

	struct signal_struct *sig =

		container_of(timer, struct signal_struct, real_timer);

	kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);

	return HRTIMER_NORESTART;

}

/*

 * Returns true if the timeval is in canonical form

 */

#define timeval_valid(t) \

	(((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))

int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)

{

	struct task_struct *tsk = current;

	struct hrtimer *timer;

	ktime_t expires;

	cputime_t cval, cinterval, nval, ninterval;

	/*

	 * Validate the timevals in value.

	 */

	if (!timeval_valid(&value->it_value) ||

	    !timeval_valid(&value->it_interval))

		return -EINVAL;

	switch (which) {

	case ITIMER_REAL:

again:

		spin_lock_irq(&tsk->sighand->siglock);

		timer = &tsk->signal->real_timer;

		if (ovalue) {

			ovalue->it_value = itimer_get_remtime(timer);

			ovalue->it_interval

				= ktime_to_timeval(tsk->signal->it_real_incr);

		}

		/* We are sharing ->siglock with it_real_fn() */

		if (hrtimer_try_to_cancel(timer) < 0) {

			spin_unlock_irq(&tsk->sighand->siglock);

			goto again;

		}

		expires = timeval_to_ktime(value->it_value);

		if (expires.tv64 != 0) {

			tsk->signal->it_real_incr =

				timeval_to_ktime(value->it_interval);

			hrtimer_start(timer, expires, HRTIMER_MODE_REL);

		} else

			tsk->signal->it_real_incr.tv64 = 0;

		spin_unlock_irq(&tsk->sighand->siglock);

		break;

	case ITIMER_VIRTUAL:

		nval = timeval_to_cputime(&value->it_value);

		ninterval = timeval_to_cputime(&value->it_interval);

		spin_lock_irq(&tsk->sighand->siglock);

		cval = tsk->signal->it_virt_expires;

		cinterval = tsk->signal->it_virt_incr;

		if (!cputime_eq(cval, cputime_zero) ||

		    !cputime_eq(nval, cputime_zero)) {

			if (cputime_gt(nval, cputime_zero))

				nval = cputime_add(nval,

						   jiffies_to_cputime(1));

			set_process_cpu_timer(tsk, CPUCLOCK_VIRT,

					      &nval, &cval);

		}

		tsk->signal->it_virt_expires = nval;

		tsk->signal->it_virt_incr = ninterval;

		spin_unlock_irq(&tsk->sighand->siglock);

		if (ovalue) {

			cputime_to_timeval(cval, &ovalue->it_value);

			cputime_to_timeval(cinterval, &ovalue->it_interval);

		}

		break;

	case ITIMER_PROF:

		nval = timeval_to_cputime(&value->it_value);

		ninterval = timeval_to_cputime(&value->it_interval);

		spin_lock_irq(&tsk->sighand->siglock);

		cval = tsk->signal->it_prof_expires;

		cinterval = tsk->signal->it_prof_incr;

		if (!cputime_eq(cval, cputime_zero) ||

		    !cputime_eq(nval, cputime_zero)) {

			if (cputime_gt(nval, cputime_zero))

				nval = cputime_add(nval,

						   jiffies_to_cputime(1));

			set_process_cpu_timer(tsk, CPUCLOCK_PROF,

					      &nval, &cval);

		}

		tsk->signal->it_prof_expires = nval;

		tsk->signal->it_prof_incr = ninterval;

		spin_unlock_irq(&tsk->sighand->siglock);

		if (ovalue) {

			cputime_to_timeval(cval, &ovalue->it_value);

			cputime_to_timeval(cinterval, &ovalue->it_interval);

		}

		break;

	default:

		return -EINVAL;

	}

	return 0;

}

/**

 * alarm_setitimer - set alarm in seconds

 *

 * @seconds:	number of seconds until alarm

 *		0 disables the alarm

 *

 * Returns the remaining time in seconds of a pending timer or 0 when

 * the timer is not active.

 *

 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid

 * negative timeval settings which would cause immediate expiry.

 */

unsigned int alarm_setitimer(unsigned int seconds)

{

	struct itimerval it_new, it_old;

#if BITS_PER_LONG < 64

	if (seconds > INT_MAX)

		seconds = INT_MAX;

#endif

	it_new.it_value.tv_sec = seconds;

	it_new.it_value.tv_usec = 0;

	it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;

	do_setitimer(ITIMER_REAL, &it_new, &it_old);

	/*

	 * We can't return 0 if we have an alarm pending ...  And we'd

	 * better return too much than too little anyway

	 */

	if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||

	      it_old.it_value.tv_usec >= 500000)

		it_old.it_value.tv_sec++;

	return it_old.it_value.tv_sec;

}

{

	struct itimerval set_buffer, get_buffer;

	int error;

	if (value) {

		if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))

			return -EFAULT;

	} else

		memset((char *) &set_buffer, 0, sizeof(set_buffer));

	error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);

	if (error || !ovalue)

		return error;

	if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))

		return -EFAULT;

	return 0;

}