[linux.git] / kernel / itimer.c

/*
 * 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);

	/*
	 * 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 (!cputime_eq(cval, cputime_zero)) {
		struct task_cputime cputime;
		cputime_t t;

		thread_group_cputimer(tsk, &cputime);
		if (clock_id == CPUCLOCK_PROF)
			t = cputime_add(cputime.utime, cputime.stime);
		else
			/* CPUCLOCK_VIRT */
			t = cputime.utime;

		if (cputime_le(cval, t))
			/* about to fire */
			cval = cputime_one_jiffy;
		else
			cval = cputime_sub(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 (!cputime_eq(cval, cputime_zero) ||
	    !cputime_eq(nval, cputime_zero)) {
		if (cputime_gt(nval, cputime_zero))
			nval = cputime_add(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((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;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/kernel/itimer.c
	3	*
	4	* Copyright (C) 1992 Darren Senn
	5	*/
	6
	7	/* These are all the functions necessary to implement itimers */
	8
	9	#include <linux/mm.h>
1da177e4 LT	10	#include <linux/interrupt.h>
	11	#include <linux/syscalls.h>
	12	#include <linux/time.h>
	13	#include <linux/posix-timers.h>
2ff678b8	14	#include <linux/hrtimer.h>
3f0a525e	15	#include <trace/events/timer.h>
1da177e4 LT	16
	17	#include <asm/uaccess.h>
	18
2ff678b8 TG	19	/**
	20	* itimer_get_remtime - get remaining time for the timer
	21	*
	22	* @timer: the timer to read
	23	*
	24	* Returns the delta between the expiry time and now, which can be
	25	* less than zero or 1usec for an pending expired timer
	26	*/
	27	static struct timeval itimer_get_remtime(struct hrtimer *timer)
1da177e4	28	{
2ff678b8	29	ktime_t rem = hrtimer_get_remaining(timer);
1da177e4	30
2ff678b8 TG	31	/*
	32	* Racy but safe: if the itimer expires after the above
	33	* hrtimer_get_remtime() call but before this condition
	34	* then we return 0 - which is correct.
	35	*/
	36	if (hrtimer_active(timer)) {
	37	if (rem.tv64 <= 0)
	38	rem.tv64 = NSEC_PER_USEC;
	39	} else
	40	rem.tv64 = 0;
	41
	42	return ktime_to_timeval(rem);
1da177e4 LT	43	}
1da177e4 LT	44
42c4ab41	45	static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
8356b5f9	46	struct itimerval *const value)
42c4ab41 SG	47	{
	48	cputime_t cval, cinterval;
	49	struct cpu_itimer *it = &tsk->signal->it[clock_id];
	50
	51	spin_lock_irq(&tsk->sighand->siglock);
	52
	53	cval = it->expires;
	54	cinterval = it->incr;
	55	if (!cputime_eq(cval, cputime_zero)) {
	56	struct task_cputime cputime;
	57	cputime_t t;
	58
	59	thread_group_cputimer(tsk, &cputime);
	60	if (clock_id == CPUCLOCK_PROF)
	61	t = cputime_add(cputime.utime, cputime.stime);
	62	else
	63	/* CPUCLOCK_VIRT */
	64	t = cputime.utime;
	65
	66	if (cputime_le(cval, t))
	67	/* about to fire */
a42548a1	68	cval = cputime_one_jiffy;
42c4ab41 SG	69	else
	70	cval = cputime_sub(cval, t);
	71	}
	72
	73	spin_unlock_irq(&tsk->sighand->siglock);
	74
	75	cputime_to_timeval(cval, &value->it_value);
	76	cputime_to_timeval(cinterval, &value->it_interval);
	77	}
	78
1da177e4 LT	79	int do_getitimer(int which, struct itimerval *value)
	80	{
	81	struct task_struct *tsk = current;
1da177e4 LT	82
	83	switch (which) {
	84	case ITIMER_REAL:
bc1978d4	85	spin_lock_irq(&tsk->sighand->siglock);
2ff678b8 TG	86	value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
	87	value->it_interval =
	88	ktime_to_timeval(tsk->signal->it_real_incr);
bc1978d4	89	spin_unlock_irq(&tsk->sighand->siglock);
1da177e4 LT	90	break;
1da177e4 LT	91	case ITIMER_VIRTUAL:
42c4ab41	92	get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
1da177e4 LT	93	break;
1da177e4 LT	94	case ITIMER_PROF:
42c4ab41	95	get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
1da177e4 LT	96	break;
	97	default:
	98	return(-EINVAL);
	99	}
	100	return 0;
	101	}
	102
b290ebe2	103	SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
1da177e4 LT	104	{
	105	int error = -EFAULT;
	106	struct itimerval get_buffer;
	107
	108	if (value) {
	109	error = do_getitimer(which, &get_buffer);
	110	if (!error &&
	111	copy_to_user(value, &get_buffer, sizeof(get_buffer)))
	112	error = -EFAULT;
	113	}
	114	return error;
	115	}
	116
1da177e4	117
2ff678b8 TG	118	/*
	119	* The timer is automagically restarted, when interval != 0
	120	*/
c9cb2e3d	121	enum hrtimer_restart it_real_fn(struct hrtimer *timer)
1da177e4	122	{
05cfb614	123	struct signal_struct *sig =
0719e370	124	container_of(timer, struct signal_struct, real_timer);
1da177e4	125
3f0a525e	126	trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
fea9d175	127	kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
2ff678b8	128
2ff678b8	129	return HRTIMER_NORESTART;
1da177e4 LT	130	}
1da177e4 LT	131
8356b5f9 SG	132	static inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns)
	133	{
	134	struct timespec ts;
	135	s64 cpu_ns;
	136
	137	cputime_to_timespec(ct, &ts);
	138	cpu_ns = timespec_to_ns(&ts);
	139
	140	return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns;
	141	}
	142
42c4ab41	143	static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
8356b5f9 SG	144	const struct itimerval *const value,
8356b5f9 SG	145	struct itimerval *const ovalue)
42c4ab41	146	{
8356b5f9 SG	147	cputime_t cval, nval, cinterval, ninterval;
8356b5f9 SG	148	s64 ns_ninterval, ns_nval;
8747d793	149	u32 error, incr_error;
42c4ab41 SG	150	struct cpu_itimer *it = &tsk->signal->it[clock_id];
	151
	152	nval = timeval_to_cputime(&value->it_value);
8356b5f9	153	ns_nval = timeval_to_ns(&value->it_value);
42c4ab41	154	ninterval = timeval_to_cputime(&value->it_interval);
8356b5f9 SG	155	ns_ninterval = timeval_to_ns(&value->it_interval);
8356b5f9 SG	156
8747d793 SG	157	error = cputime_sub_ns(nval, ns_nval);
8747d793 SG	158	incr_error = cputime_sub_ns(ninterval, ns_ninterval);
42c4ab41 SG	159
	160	spin_lock_irq(&tsk->sighand->siglock);
	161
	162	cval = it->expires;
	163	cinterval = it->incr;
	164	if (!cputime_eq(cval, cputime_zero) \|\|
	165	!cputime_eq(nval, cputime_zero)) {
	166	if (cputime_gt(nval, cputime_zero))
a42548a1	167	nval = cputime_add(nval, cputime_one_jiffy);
42c4ab41 SG	168	set_process_cpu_timer(tsk, clock_id, &nval, &cval);
	169	}
	170	it->expires = nval;
	171	it->incr = ninterval;
8747d793 SG	172	it->error = error;
8747d793 SG	173	it->incr_error = incr_error;
3f0a525e XG	174	trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
3f0a525e XG	175	ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
42c4ab41 SG	176
	177	spin_unlock_irq(&tsk->sighand->siglock);
	178
	179	if (ovalue) {
	180	cputime_to_timeval(cval, &ovalue->it_value);
	181	cputime_to_timeval(cinterval, &ovalue->it_interval);
	182	}
	183	}
	184
7d99b7d6 TG	185	/*
	186	* Returns true if the timeval is in canonical form
	187	*/
	188	#define timeval_valid(t) \
	189	(((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
	190
1da177e4 LT	191	int do_setitimer(int which, struct itimerval value, struct itimerval ovalue)
	192	{
	193	struct task_struct *tsk = current;
2ff678b8 TG	194	struct hrtimer *timer;
2ff678b8 TG	195	ktime_t expires;
1da177e4	196
7d99b7d6 TG	197	/*
7d99b7d6 TG	198	* Validate the timevals in value.
7d99b7d6	199	*/
35bab756 AB	200	if (!timeval_valid(&value->it_value) \|\|
	201	!timeval_valid(&value->it_interval))
	202	return -EINVAL;
7d99b7d6	203
1da177e4 LT	204	switch (which) {
1da177e4 LT	205	case ITIMER_REAL:
bc1978d4 TG	206	again:
bc1978d4 TG	207	spin_lock_irq(&tsk->sighand->siglock);
2ff678b8	208	timer = &tsk->signal->real_timer;
1da177e4	209	if (ovalue) {
2ff678b8 TG	210	ovalue->it_value = itimer_get_remtime(timer);
	211	ovalue->it_interval
	212	= ktime_to_timeval(tsk->signal->it_real_incr);
1da177e4	213	}
a16a1c09 TG	214	/* We are sharing ->siglock with it_real_fn() */
	215	if (hrtimer_try_to_cancel(timer) < 0) {
	216	spin_unlock_irq(&tsk->sighand->siglock);
	217	goto again;
	218	}
2ff678b8	219	expires = timeval_to_ktime(value->it_value);
8bfd9a7a TG	220	if (expires.tv64 != 0) {
	221	tsk->signal->it_real_incr =
	222	timeval_to_ktime(value->it_interval);
c9cb2e3d	223	hrtimer_start(timer, expires, HRTIMER_MODE_REL);
8bfd9a7a TG	224	} else
	225	tsk->signal->it_real_incr.tv64 = 0;
	226
3f0a525e	227	trace_itimer_state(ITIMER_REAL, value, 0);
bc1978d4	228	spin_unlock_irq(&tsk->sighand->siglock);
1da177e4 LT	229	break;
1da177e4 LT	230	case ITIMER_VIRTUAL:
42c4ab41	231	set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
1da177e4 LT	232	break;
1da177e4 LT	233	case ITIMER_PROF:
42c4ab41	234	set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
1da177e4 LT	235	break;
	236	default:
	237	return -EINVAL;
	238	}
	239	return 0;
	240	}
	241
c08b8a49 TG	242	/**
	243	* alarm_setitimer - set alarm in seconds
	244	*
	245	* @seconds: number of seconds until alarm
	246	* 0 disables the alarm
	247	*
	248	* Returns the remaining time in seconds of a pending timer or 0 when
	249	* the timer is not active.
	250	*
	251	* On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
	252	* negative timeval settings which would cause immediate expiry.
	253	*/
	254	unsigned int alarm_setitimer(unsigned int seconds)
	255	{
	256	struct itimerval it_new, it_old;
	257
	258	#if BITS_PER_LONG < 64
	259	if (seconds > INT_MAX)
	260	seconds = INT_MAX;
	261	#endif
	262	it_new.it_value.tv_sec = seconds;
	263	it_new.it_value.tv_usec = 0;
	264	it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
	265
	266	do_setitimer(ITIMER_REAL, &it_new, &it_old);
	267
	268	/*
	269	* We can't return 0 if we have an alarm pending ... And we'd
	270	* better return too much than too little anyway
	271	*/
	272	if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) \|\|
	273	it_old.it_value.tv_usec >= 500000)
	274	it_old.it_value.tv_sec++;
	275
	276	return it_old.it_value.tv_sec;
	277	}
	278
362e9c07 HC	279	SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
362e9c07 HC	280	struct itimerval __user *, ovalue)
1da177e4 LT	281	{
	282	struct itimerval set_buffer, get_buffer;
	283	int error;
	284
	285	if (value) {
	286	if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
	287	return -EFAULT;
	288	} else
	289	memset((char *) &set_buffer, 0, sizeof(set_buffer));
	290
	291	error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
	292	if (error \|\| !ovalue)
	293	return error;
	294
	295	if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
0719e370	296	return -EFAULT;
1da177e4 LT	297	return 0;
1da177e4 LT	298	}