/* * 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; 			thread_group_cputimer(tsk, &cputime);			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; 			thread_group_cputimer(tsk, &times);			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;} SYSCALL_DEFINE2(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); 	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;} SYSCALL_DEFINE3(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;}