/* * 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 <trace/events/timer.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, true); 	/*	 * 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);} static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,			   struct itimerval *const value){	cputime_t cval, cinterval;	struct cpu_itimer *it = &tsk->signal->it[clock_id]; 	spin_lock_irq(&tsk->sighand->siglock); 	cval = it->expires;	cinterval = it->incr;	if (cval) {		struct task_cputime cputime;		cputime_t t; 		thread_group_cputimer(tsk, &cputime);		if (clock_id == CPUCLOCK_PROF)			t = cputime.utime + cputime.stime;		else			/* CPUCLOCK_VIRT */			t = cputime.utime; 		if (cval < t)			/* about to fire */			cval = cputime_one_jiffy;		else			cval = cval - t;	} 	spin_unlock_irq(&tsk->sighand->siglock); 	cputime_to_timeval(cval, &value->it_value);	cputime_to_timeval(cinterval, &value->it_interval);} int do_getitimer(int which, struct itimerval *value){	struct task_struct *tsk = current; 	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:		get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);		break;	case ITIMER_PROF:		get_cpu_itimer(tsk, CPUCLOCK_PROF, value);		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); 	trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);	kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid); 	return HRTIMER_NORESTART;} static inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns){	struct timespec ts;	s64 cpu_ns; 	cputime_to_timespec(ct, &ts);	cpu_ns = timespec_to_ns(&ts); 	return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns;} static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,			   const struct itimerval *const value,			   struct itimerval *const ovalue){	cputime_t cval, nval, cinterval, ninterval;	s64 ns_ninterval, ns_nval;	u32 error, incr_error;	struct cpu_itimer *it = &tsk->signal->it[clock_id]; 	nval = timeval_to_cputime(&value->it_value);	ns_nval = timeval_to_ns(&value->it_value);	ninterval = timeval_to_cputime(&value->it_interval);	ns_ninterval = timeval_to_ns(&value->it_interval); 	error = cputime_sub_ns(nval, ns_nval);	incr_error = cputime_sub_ns(ninterval, ns_ninterval); 	spin_lock_irq(&tsk->sighand->siglock); 	cval = it->expires;	cinterval = it->incr;	if (cval || nval) {		if (nval > 0)			nval += cputime_one_jiffy;		set_process_cpu_timer(tsk, clock_id, &nval, &cval);	}	it->expires = nval;	it->incr = ninterval;	it->error = error;	it->incr_error = incr_error;	trace_itimer_state(clock_id == CPUCLOCK_VIRT ?			   ITIMER_VIRTUAL : ITIMER_PROF, value, nval); 	spin_unlock_irq(&tsk->sighand->siglock); 	if (ovalue) {		cputime_to_timeval(cval, &ovalue->it_value);		cputime_to_timeval(cinterval, &ovalue->it_interval);	}} /* * 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; 	/*	 * 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; 		trace_itimer_state(ITIMER_REAL, value, 0);		spin_unlock_irq(&tsk->sighand->siglock);		break;	case ITIMER_VIRTUAL:		set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);		break;	case ITIMER_PROF:		set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);		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(&set_buffer, 0, sizeof(set_buffer));		printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."			    " Misfeature support will be removed\n",			    current->comm);	} 	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;}