[mirror_ubuntu-artful-kernel.git] / kernel / time / 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/sched/signal.h>
#include <linux/sched/cputime.h>
#include <linux/posix-timers.h>
#include <linux/hrtimer.h>
#include <trace/events/timer.h>
#include <linux/compat.h>

#include <linux/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 <= 0)
			rem = NSEC_PER_USEC;
	} else
		rem = 0;

	return ktime_to_timeval(rem);
}

static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
			   struct itimerval *const value)
{
	u64 val, interval;
	struct cpu_itimer *it = &tsk->signal->it[clock_id];

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

	val = it->expires;
	interval = it->incr;
	if (val) {
		struct task_cputime cputime;
		u64 t;

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

		if (val < t)
			/* about to fire */
			val = TICK_NSEC;
		else
			val -= t;
	}

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

	value->it_value = ns_to_timeval(val);
	value->it_interval = ns_to_timeval(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;
}

#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
		       struct compat_itimerval __user *, it)
{
	struct itimerval kit;
	int error = do_getitimer(which, &kit);

	if (!error && put_compat_itimerval(it, &kit))
		error = -EFAULT;
	return error;
}
#endif


/*
 * 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 void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
			   const struct itimerval *const value,
			   struct itimerval *const ovalue)
{
	u64 oval, nval, ointerval, ninterval;
	struct cpu_itimer *it = &tsk->signal->it[clock_id];

	/*
	 * Use the to_ktime conversion because that clamps the maximum
	 * value to KTIME_MAX and avoid multiplication overflows.
	 */
	nval = ktime_to_ns(timeval_to_ktime(value->it_value));
	ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));

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

	oval = it->expires;
	ointerval = it->incr;
	if (oval || nval) {
		if (nval > 0)
			nval += TICK_NSEC;
		set_process_cpu_timer(tsk, clock_id, &nval, &oval);
	}
	it->expires = nval;
	it->incr = ninterval;
	trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
			   ITIMER_VIRTUAL : ITIMER_PROF, value, nval);

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

	if (ovalue) {
		ovalue->it_value = ns_to_timeval(oval);
		ovalue->it_interval = ns_to_timeval(ointerval);
	}
}

/*
 * 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 != 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 = 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;
}

#ifdef __ARCH_WANT_SYS_ALARM

/**
 * 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.
 */
static 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;
}

/*
 * For backwards compatibility?  This can be done in libc so Alpha
 * and all newer ports shouldn't need it.
 */
SYSCALL_DEFINE1(alarm, unsigned int, seconds)
{
	return alarm_setitimer(seconds);
}

#endif

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;
}

#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
		       struct compat_itimerval __user *, in,
		       struct compat_itimerval __user *, out)
{
	struct itimerval kin, kout;
	int error;

	if (in) {
		if (get_compat_itimerval(&kin, in))
			return -EFAULT;
	} else {
		memset(&kin, 0, sizeof(kin));
	}

	error = do_setitimer(which, &kin, out ? &kout : NULL);
	if (error || !out)
		return error;
	if (put_compat_itimerval(out, &kout))
		return -EFAULT;
	return 0;
}
#endif
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>
3f07c014	13	#include <linux/sched/signal.h>
32ef5517	14	#include <linux/sched/cputime.h>
1da177e4	15	#include <linux/posix-timers.h>
2ff678b8	16	#include <linux/hrtimer.h>
3f0a525e	17	#include <trace/events/timer.h>
54ad9c46	18	#include <linux/compat.h>
1da177e4	19
7c0f6ba6	20	#include <linux/uaccess.h>
1da177e4	21
2ff678b8 TG	22	/**
	23	* itimer_get_remtime - get remaining time for the timer
	24	*
	25	* @timer: the timer to read
	26	*
	27	* Returns the delta between the expiry time and now, which can be
	28	* less than zero or 1usec for an pending expired timer
	29	*/
	30	static struct timeval itimer_get_remtime(struct hrtimer *timer)
1da177e4	31	{
51cbb524	32	ktime_t rem = __hrtimer_get_remaining(timer, true);
1da177e4	33
2ff678b8 TG	34	/*
	35	* Racy but safe: if the itimer expires after the above
	36	* hrtimer_get_remtime() call but before this condition
	37	* then we return 0 - which is correct.
	38	*/
	39	if (hrtimer_active(timer)) {
2456e855 TG	40	if (rem <= 0)
2456e855 TG	41	rem = NSEC_PER_USEC;
2ff678b8	42	} else
2456e855	43	rem = 0;
2ff678b8 TG	44
2ff678b8 TG	45	return ktime_to_timeval(rem);
1da177e4 LT	46	}
1da177e4 LT	47
42c4ab41	48	static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
8356b5f9	49	struct itimerval *const value)
42c4ab41	50	{
858cf3a8	51	u64 val, interval;
42c4ab41 SG	52	struct cpu_itimer *it = &tsk->signal->it[clock_id];
	53
	54	spin_lock_irq(&tsk->sighand->siglock);
	55
858cf3a8 FW	56	val = it->expires;
	57	interval = it->incr;
	58	if (val) {
ebd7e7fc	59	struct task_cputime cputime;
858cf3a8	60	u64 t;
42c4ab41 SG	61
	62	thread_group_cputimer(tsk, &cputime);
	63	if (clock_id == CPUCLOCK_PROF)
858cf3a8	64	t = cputime.utime + cputime.stime;
42c4ab41 SG	65	else
42c4ab41 SG	66	/* CPUCLOCK_VIRT */
858cf3a8	67	t = cputime.utime;
42c4ab41	68
858cf3a8	69	if (val < t)
42c4ab41	70	/* about to fire */
858cf3a8	71	val = TICK_NSEC;
42c4ab41	72	else
858cf3a8	73	val -= t;
42c4ab41 SG	74	}
	75
	76	spin_unlock_irq(&tsk->sighand->siglock);
	77
858cf3a8 FW	78	value->it_value = ns_to_timeval(val);
858cf3a8 FW	79	value->it_interval = ns_to_timeval(interval);
42c4ab41 SG	80	}
42c4ab41 SG	81
1da177e4 LT	82	int do_getitimer(int which, struct itimerval *value)
	83	{
	84	struct task_struct *tsk = current;
1da177e4 LT	85
	86	switch (which) {
	87	case ITIMER_REAL:
bc1978d4	88	spin_lock_irq(&tsk->sighand->siglock);
2ff678b8 TG	89	value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
	90	value->it_interval =
	91	ktime_to_timeval(tsk->signal->it_real_incr);
bc1978d4	92	spin_unlock_irq(&tsk->sighand->siglock);
1da177e4 LT	93	break;
1da177e4 LT	94	case ITIMER_VIRTUAL:
42c4ab41	95	get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
1da177e4 LT	96	break;
1da177e4 LT	97	case ITIMER_PROF:
42c4ab41	98	get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
1da177e4 LT	99	break;
	100	default:
	101	return(-EINVAL);
	102	}
	103	return 0;
	104	}
	105
b290ebe2	106	SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
1da177e4 LT	107	{
	108	int error = -EFAULT;
	109	struct itimerval get_buffer;
	110
	111	if (value) {
	112	error = do_getitimer(which, &get_buffer);
	113	if (!error &&
	114	copy_to_user(value, &get_buffer, sizeof(get_buffer)))
	115	error = -EFAULT;
	116	}
	117	return error;
	118	}
	119
54ad9c46 AV	120	#ifdef CONFIG_COMPAT
	121	COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
	122	struct compat_itimerval __user *, it)
	123	{
	124	struct itimerval kit;
	125	int error = do_getitimer(which, &kit);
	126
	127	if (!error && put_compat_itimerval(it, &kit))
	128	error = -EFAULT;
	129	return error;
	130	}
	131	#endif
	132
1da177e4	133
2ff678b8 TG	134	/*
	135	* The timer is automagically restarted, when interval != 0
	136	*/
c9cb2e3d	137	enum hrtimer_restart it_real_fn(struct hrtimer *timer)
1da177e4	138	{
05cfb614	139	struct signal_struct *sig =
0719e370	140	container_of(timer, struct signal_struct, real_timer);
1da177e4	141
3f0a525e	142	trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
fea9d175	143	kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
2ff678b8	144
2ff678b8	145	return HRTIMER_NORESTART;
1da177e4 LT	146	}
1da177e4 LT	147
42c4ab41	148	static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
8356b5f9 SG	149	const struct itimerval *const value,
8356b5f9 SG	150	struct itimerval *const ovalue)
42c4ab41	151	{
858cf3a8	152	u64 oval, nval, ointerval, ninterval;
42c4ab41 SG	153	struct cpu_itimer *it = &tsk->signal->it[clock_id];
42c4ab41 SG	154
35eb7258 TG	155	/*
	156	* Use the to_ktime conversion because that clamps the maximum
	157	* value to KTIME_MAX and avoid multiplication overflows.
	158	*/
	159	nval = ktime_to_ns(timeval_to_ktime(value->it_value));
	160	ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));
42c4ab41 SG	161
	162	spin_lock_irq(&tsk->sighand->siglock);
	163
858cf3a8 FW	164	oval = it->expires;
	165	ointerval = it->incr;
	166	if (oval \|\| nval) {
64861634	167	if (nval > 0)
858cf3a8 FW	168	nval += TICK_NSEC;
858cf3a8 FW	169	set_process_cpu_timer(tsk, clock_id, &nval, &oval);
42c4ab41 SG	170	}
	171	it->expires = nval;
	172	it->incr = ninterval;
3f0a525e XG	173	trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
3f0a525e XG	174	ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
42c4ab41 SG	175
	176	spin_unlock_irq(&tsk->sighand->siglock);
	177
	178	if (ovalue) {
858cf3a8 FW	179	ovalue->it_value = ns_to_timeval(oval);
858cf3a8 FW	180	ovalue->it_interval = ns_to_timeval(ointerval);
42c4ab41 SG	181	}
	182	}
	183
7d99b7d6 TG	184	/*
	185	* Returns true if the timeval is in canonical form
	186	*/
	187	#define timeval_valid(t) \
	188	(((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
	189
1da177e4 LT	190	int do_setitimer(int which, struct itimerval value, struct itimerval ovalue)
	191	{
	192	struct task_struct *tsk = current;
2ff678b8 TG	193	struct hrtimer *timer;
2ff678b8 TG	194	ktime_t expires;
1da177e4	195
7d99b7d6 TG	196	/*
7d99b7d6 TG	197	* Validate the timevals in value.
7d99b7d6	198	*/
35bab756 AB	199	if (!timeval_valid(&value->it_value) \|\|
	200	!timeval_valid(&value->it_interval))
	201	return -EINVAL;
7d99b7d6	202
1da177e4 LT	203	switch (which) {
1da177e4 LT	204	case ITIMER_REAL:
bc1978d4 TG	205	again:
bc1978d4 TG	206	spin_lock_irq(&tsk->sighand->siglock);
2ff678b8	207	timer = &tsk->signal->real_timer;
1da177e4	208	if (ovalue) {
2ff678b8 TG	209	ovalue->it_value = itimer_get_remtime(timer);
	210	ovalue->it_interval
	211	= ktime_to_timeval(tsk->signal->it_real_incr);
1da177e4	212	}
a16a1c09 TG	213	/* We are sharing ->siglock with it_real_fn() */
	214	if (hrtimer_try_to_cancel(timer) < 0) {
	215	spin_unlock_irq(&tsk->sighand->siglock);
	216	goto again;
	217	}
2ff678b8	218	expires = timeval_to_ktime(value->it_value);
2456e855	219	if (expires != 0) {
8bfd9a7a TG	220	tsk->signal->it_real_incr =
8bfd9a7a TG	221	timeval_to_ktime(value->it_interval);
c9cb2e3d	222	hrtimer_start(timer, expires, HRTIMER_MODE_REL);
8bfd9a7a	223	} else
2456e855	224	tsk->signal->it_real_incr = 0;
8bfd9a7a	225
3f0a525e	226	trace_itimer_state(ITIMER_REAL, value, 0);
bc1978d4	227	spin_unlock_irq(&tsk->sighand->siglock);
1da177e4 LT	228	break;
1da177e4 LT	229	case ITIMER_VIRTUAL:
42c4ab41	230	set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
1da177e4 LT	231	break;
1da177e4 LT	232	case ITIMER_PROF:
42c4ab41	233	set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
1da177e4 LT	234	break;
	235	default:
	236	return -EINVAL;
	237	}
	238	return 0;
	239	}
	240
74ba181e NP	241	#ifdef __ARCH_WANT_SYS_ALARM
74ba181e NP	242
c08b8a49 TG	243	/**
	244	* alarm_setitimer - set alarm in seconds
	245	*
	246	* @seconds: number of seconds until alarm
	247	* 0 disables the alarm
	248	*
	249	* Returns the remaining time in seconds of a pending timer or 0 when
	250	* the timer is not active.
	251	*
	252	* On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
	253	* negative timeval settings which would cause immediate expiry.
	254	*/
74ba181e	255	static unsigned int alarm_setitimer(unsigned int seconds)
c08b8a49 TG	256	{
	257	struct itimerval it_new, it_old;
	258
	259	#if BITS_PER_LONG < 64
	260	if (seconds > INT_MAX)
	261	seconds = INT_MAX;
	262	#endif
	263	it_new.it_value.tv_sec = seconds;
	264	it_new.it_value.tv_usec = 0;
	265	it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
	266
	267	do_setitimer(ITIMER_REAL, &it_new, &it_old);
	268
	269	/*
	270	* We can't return 0 if we have an alarm pending ... And we'd
	271	* better return too much than too little anyway
	272	*/
	273	if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) \|\|
	274	it_old.it_value.tv_usec >= 500000)
	275	it_old.it_value.tv_sec++;
	276
	277	return it_old.it_value.tv_sec;
	278	}
	279
74ba181e NP	280	/*
	281	* For backwards compatibility? This can be done in libc so Alpha
	282	* and all newer ports shouldn't need it.
	283	*/
	284	SYSCALL_DEFINE1(alarm, unsigned int, seconds)
	285	{
	286	return alarm_setitimer(seconds);
	287	}
	288
	289	#endif
	290
362e9c07 HC	291	SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
362e9c07 HC	292	struct itimerval __user *, ovalue)
1da177e4 LT	293	{
	294	struct itimerval set_buffer, get_buffer;
	295	int error;
	296
	297	if (value) {
	298	if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
	299	return -EFAULT;
aa2bf9bc	300	} else {
9886f444 TG	301	memset(&set_buffer, 0, sizeof(set_buffer));
	302	printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
	303	" Misfeature support will be removed\n",
	304	current->comm);
aa2bf9bc	305	}
1da177e4 LT	306
	307	error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
	308	if (error \|\| !ovalue)
	309	return error;
	310
	311	if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
0719e370	312	return -EFAULT;
1da177e4 LT	313	return 0;
1da177e4 LT	314	}
54ad9c46 AV	315
	316	#ifdef CONFIG_COMPAT
	317	COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
	318	struct compat_itimerval __user *, in,
	319	struct compat_itimerval __user *, out)
	320	{
	321	struct itimerval kin, kout;
	322	int error;
	323
	324	if (in) {
	325	if (get_compat_itimerval(&kin, in))
	326	return -EFAULT;
	327	} else {
	328	memset(&kin, 0, sizeof(kin));
	329	}
	330
	331	error = do_setitimer(which, &kin, out ? &kout : NULL);
	332	if (error \|\| !out)
	333	return error;
	334	if (put_compat_itimerval(out, &kout))
	335	return -EFAULT;
	336	return 0;
	337	}
	338	#endif