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/*

 * 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:

                read_lock(&tasklist_lock);

                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_struct *t = tsk;

                        cputime_t utime = tsk->signal->utime;

                        do {

                                utime = cputime_add(utime, t->utime);

                                t = next_thread(t);

                        } while (t != tsk);

                        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);

                read_unlock(&tasklist_lock);

                cputime_to_timeval(cval, &value->it_value);

                cputime_to_timeval(cinterval, &value->it_interval);

                break;

        case ITIMER_PROF:

                read_lock(&tasklist_lock);

                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_struct *t = tsk;

                        cputime_t ptime = cputime_add(tsk->signal->utime,

                                                      tsk->signal->stime);

                        do {

                                ptime = cputime_add(ptime,

                                                    cputime_add(t->utime,

                                                                t->stime));

                                t = next_thread(t);

                        } while (t != tsk);

                        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);

                read_unlock(&tasklist_lock);

                cputime_to_timeval(cval, &value->it_value);

                cputime_to_timeval(cinterval, &value->it_interval);

                break;

        default:

                return(-EINVAL);

        }

        return 0;

}

asmlinkage long sys_getitimer(int which, struct itimerval __user *value)

{

        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);

        send_group_sig_info(SIGALRM, SEND_SIG_PRIV, sig->tsk);

        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);

                read_lock(&tasklist_lock);

                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);

                read_unlock(&tasklist_lock);

                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);

                read_lock(&tasklist_lock);

                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);

                read_unlock(&tasklist_lock);

                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;

}

asmlinkage long sys_setitimer(int which,

                              struct itimerval __user *value,

                              struct itimerval __user *ovalue)

{

        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;

}