[linux-2.6-block.git] / kernel / futex / syscalls.c

// SPDX-License-Identifier: GPL-2.0-or-later

#include <linux/compat.h>
#include <linux/syscalls.h>
#include <linux/time_namespace.h>

#include "futex.h"

/*
 * Support for robust futexes: the kernel cleans up held futexes at
 * thread exit time.
 *
 * Implementation: user-space maintains a per-thread list of locks it
 * is holding. Upon do_exit(), the kernel carefully walks this list,
 * and marks all locks that are owned by this thread with the
 * FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is
 * always manipulated with the lock held, so the list is private and
 * per-thread. Userspace also maintains a per-thread 'list_op_pending'
 * field, to allow the kernel to clean up if the thread dies after
 * acquiring the lock, but just before it could have added itself to
 * the list. There can only be one such pending lock.
 */

/**
 * sys_set_robust_list() - Set the robust-futex list head of a task
 * @head:	pointer to the list-head
 * @len:	length of the list-head, as userspace expects
 */
SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head,
		size_t, len)
{
	/*
	 * The kernel knows only one size for now:
	 */
	if (unlikely(len != sizeof(*head)))
		return -EINVAL;

	current->robust_list = head;

	return 0;
}

/**
 * sys_get_robust_list() - Get the robust-futex list head of a task
 * @pid:	pid of the process [zero for current task]
 * @head_ptr:	pointer to a list-head pointer, the kernel fills it in
 * @len_ptr:	pointer to a length field, the kernel fills in the header size
 */
SYSCALL_DEFINE3(get_robust_list, int, pid,
		struct robust_list_head __user * __user *, head_ptr,
		size_t __user *, len_ptr)
{
	struct robust_list_head __user *head;
	unsigned long ret;
	struct task_struct *p;

	rcu_read_lock();

	ret = -ESRCH;
	if (!pid)
		p = current;
	else {
		p = find_task_by_vpid(pid);
		if (!p)
			goto err_unlock;
	}

	ret = -EPERM;
	if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS))
		goto err_unlock;

	head = p->robust_list;
	rcu_read_unlock();

	if (put_user(sizeof(*head), len_ptr))
		return -EFAULT;
	return put_user(head, head_ptr);

err_unlock:
	rcu_read_unlock();

	return ret;
}

long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
		u32 __user *uaddr2, u32 val2, u32 val3)
{
	int cmd = op & FUTEX_CMD_MASK;
	unsigned int flags = 0;

	if (!(op & FUTEX_PRIVATE_FLAG))
		flags |= FLAGS_SHARED;

	if (op & FUTEX_CLOCK_REALTIME) {
		flags |= FLAGS_CLOCKRT;
		if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI &&
		    cmd != FUTEX_LOCK_PI2)
			return -ENOSYS;
	}

	switch (cmd) {
	case FUTEX_WAIT:
		val3 = FUTEX_BITSET_MATCH_ANY;
		fallthrough;
	case FUTEX_WAIT_BITSET:
		return futex_wait(uaddr, flags, val, timeout, val3);
	case FUTEX_WAKE:
		val3 = FUTEX_BITSET_MATCH_ANY;
		fallthrough;
	case FUTEX_WAKE_BITSET:
		return futex_wake(uaddr, flags, val, val3);
	case FUTEX_REQUEUE:
		return futex_requeue(uaddr, flags, uaddr2, val, val2, NULL, 0);
	case FUTEX_CMP_REQUEUE:
		return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 0);
	case FUTEX_WAKE_OP:
		return futex_wake_op(uaddr, flags, uaddr2, val, val2, val3);
	case FUTEX_LOCK_PI:
		flags |= FLAGS_CLOCKRT;
		fallthrough;
	case FUTEX_LOCK_PI2:
		return futex_lock_pi(uaddr, flags, timeout, 0);
	case FUTEX_UNLOCK_PI:
		return futex_unlock_pi(uaddr, flags);
	case FUTEX_TRYLOCK_PI:
		return futex_lock_pi(uaddr, flags, NULL, 1);
	case FUTEX_WAIT_REQUEUE_PI:
		val3 = FUTEX_BITSET_MATCH_ANY;
		return futex_wait_requeue_pi(uaddr, flags, val, timeout, val3,
					     uaddr2);
	case FUTEX_CMP_REQUEUE_PI:
		return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 1);
	}
	return -ENOSYS;
}

static __always_inline bool futex_cmd_has_timeout(u32 cmd)
{
	switch (cmd) {
	case FUTEX_WAIT:
	case FUTEX_LOCK_PI:
	case FUTEX_LOCK_PI2:
	case FUTEX_WAIT_BITSET:
	case FUTEX_WAIT_REQUEUE_PI:
		return true;
	}
	return false;
}

static __always_inline int
futex_init_timeout(u32 cmd, u32 op, struct timespec64 *ts, ktime_t *t)
{
	if (!timespec64_valid(ts))
		return -EINVAL;

	*t = timespec64_to_ktime(*ts);
	if (cmd == FUTEX_WAIT)
		*t = ktime_add_safe(ktime_get(), *t);
	else if (cmd != FUTEX_LOCK_PI && !(op & FUTEX_CLOCK_REALTIME))
		*t = timens_ktime_to_host(CLOCK_MONOTONIC, *t);
	return 0;
}

SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
		const struct __kernel_timespec __user *, utime,
		u32 __user *, uaddr2, u32, val3)
{
	int ret, cmd = op & FUTEX_CMD_MASK;
	ktime_t t, *tp = NULL;
	struct timespec64 ts;

	if (utime && futex_cmd_has_timeout(cmd)) {
		if (unlikely(should_fail_futex(!(op & FUTEX_PRIVATE_FLAG))))
			return -EFAULT;
		if (get_timespec64(&ts, utime))
			return -EFAULT;
		ret = futex_init_timeout(cmd, op, &ts, &t);
		if (ret)
			return ret;
		tp = &t;
	}

	return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
}

/* Mask of available flags for each futex in futex_waitv list */
#define FUTEXV_WAITER_MASK (FUTEX_32 | FUTEX_PRIVATE_FLAG)

/**
 * futex_parse_waitv - Parse a waitv array from userspace
 * @futexv:	Kernel side list of waiters to be filled
 * @uwaitv:     Userspace list to be parsed
 * @nr_futexes: Length of futexv
 *
 * Return: Error code on failure, 0 on success
 */
static int futex_parse_waitv(struct futex_vector *futexv,
			     struct futex_waitv __user *uwaitv,
			     unsigned int nr_futexes)
{
	struct futex_waitv aux;
	unsigned int i;

	for (i = 0; i < nr_futexes; i++) {
		if (copy_from_user(&aux, &uwaitv[i], sizeof(aux)))
			return -EFAULT;

		if ((aux.flags & ~FUTEXV_WAITER_MASK) || aux.__reserved)
			return -EINVAL;

		if (!(aux.flags & FUTEX_32))
			return -EINVAL;

		futexv[i].w.flags = aux.flags;
		futexv[i].w.val = aux.val;
		futexv[i].w.uaddr = aux.uaddr;
		futexv[i].q = futex_q_init;
	}

	return 0;
}

/**
 * sys_futex_waitv - Wait on a list of futexes
 * @waiters:    List of futexes to wait on
 * @nr_futexes: Length of futexv
 * @flags:      Flag for timeout (monotonic/realtime)
 * @timeout:	Optional absolute timeout.
 * @clockid:	Clock to be used for the timeout, realtime or monotonic.
 *
 * Given an array of `struct futex_waitv`, wait on each uaddr. The thread wakes
 * if a futex_wake() is performed at any uaddr. The syscall returns immediately
 * if any waiter has *uaddr != val. *timeout is an optional timeout value for
 * the operation. Each waiter has individual flags. The `flags` argument for
 * the syscall should be used solely for specifying the timeout as realtime, if
 * needed. Flags for private futexes, sizes, etc. should be used on the
 * individual flags of each waiter.
 *
 * Returns the array index of one of the woken futexes. No further information
 * is provided: any number of other futexes may also have been woken by the
 * same event, and if more than one futex was woken, the retrned index may
 * refer to any one of them. (It is not necessaryily the futex with the
 * smallest index, nor the one most recently woken, nor...)
 */

SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters,
		unsigned int, nr_futexes, unsigned int, flags,
		struct __kernel_timespec __user *, timeout, clockid_t, clockid)
{
	struct hrtimer_sleeper to;
	struct futex_vector *futexv;
	struct timespec64 ts;
	ktime_t time;
	int ret;

	/* This syscall supports no flags for now */
	if (flags)
		return -EINVAL;

	if (!nr_futexes || nr_futexes > FUTEX_WAITV_MAX || !waiters)
		return -EINVAL;

	if (timeout) {
		int flag_clkid = 0, flag_init = 0;

		if (clockid == CLOCK_REALTIME) {
			flag_clkid = FLAGS_CLOCKRT;
			flag_init = FUTEX_CLOCK_REALTIME;
		}

		if (clockid != CLOCK_REALTIME && clockid != CLOCK_MONOTONIC)
			return -EINVAL;

		if (get_timespec64(&ts, timeout))
			return -EFAULT;

		/*
		 * Since there's no opcode for futex_waitv, use
		 * FUTEX_WAIT_BITSET that uses absolute timeout as well
		 */
		ret = futex_init_timeout(FUTEX_WAIT_BITSET, flag_init, &ts, &time);
		if (ret)
			return ret;

		futex_setup_timer(&time, &to, flag_clkid, 0);
	}

	futexv = kcalloc(nr_futexes, sizeof(*futexv), GFP_KERNEL);
	if (!futexv)
		return -ENOMEM;

	ret = futex_parse_waitv(futexv, waiters, nr_futexes);
	if (!ret)
		ret = futex_wait_multiple(futexv, nr_futexes, timeout ? &to : NULL);

	if (timeout) {
		hrtimer_cancel(&to.timer);
		destroy_hrtimer_on_stack(&to.timer);
	}

	kfree(futexv);
	return ret;
}

#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(set_robust_list,
		struct compat_robust_list_head __user *, head,
		compat_size_t, len)
{
	if (unlikely(len != sizeof(*head)))
		return -EINVAL;

	current->compat_robust_list = head;

	return 0;
}

COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid,
			compat_uptr_t __user *, head_ptr,
			compat_size_t __user *, len_ptr)
{
	struct compat_robust_list_head __user *head;
	unsigned long ret;
	struct task_struct *p;

	rcu_read_lock();

	ret = -ESRCH;
	if (!pid)
		p = current;
	else {
		p = find_task_by_vpid(pid);
		if (!p)
			goto err_unlock;
	}

	ret = -EPERM;
	if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS))
		goto err_unlock;

	head = p->compat_robust_list;
	rcu_read_unlock();

	if (put_user(sizeof(*head), len_ptr))
		return -EFAULT;
	return put_user(ptr_to_compat(head), head_ptr);

err_unlock:
	rcu_read_unlock();

	return ret;
}
#endif /* CONFIG_COMPAT */

#ifdef CONFIG_COMPAT_32BIT_TIME
SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
		const struct old_timespec32 __user *, utime, u32 __user *, uaddr2,
		u32, val3)
{
	int ret, cmd = op & FUTEX_CMD_MASK;
	ktime_t t, *tp = NULL;
	struct timespec64 ts;

	if (utime && futex_cmd_has_timeout(cmd)) {
		if (get_old_timespec32(&ts, utime))
			return -EFAULT;
		ret = futex_init_timeout(cmd, op, &ts, &t);
		if (ret)
			return ret;
		tp = &t;
	}

	return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
}
#endif /* CONFIG_COMPAT_32BIT_TIME */
Commit	Line	Data
af8cc960 PZ	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2
	3	#include <linux/compat.h>
	4	#include <linux/syscalls.h>
	5	#include <linux/time_namespace.h>
	6
	7	#include "futex.h"
	8
	9	/*
	10	* Support for robust futexes: the kernel cleans up held futexes at
	11	* thread exit time.
	12	*
	13	* Implementation: user-space maintains a per-thread list of locks it
	14	* is holding. Upon do_exit(), the kernel carefully walks this list,
	15	* and marks all locks that are owned by this thread with the
	16	* FUTEX_OWNER_DIED bit, and wakes up a waiter (if any). The list is
	17	* always manipulated with the lock held, so the list is private and
	18	* per-thread. Userspace also maintains a per-thread 'list_op_pending'
	19	* field, to allow the kernel to clean up if the thread dies after
	20	* acquiring the lock, but just before it could have added itself to
	21	* the list. There can only be one such pending lock.
	22	*/
	23
	24	/**
	25	* sys_set_robust_list() - Set the robust-futex list head of a task
	26	* @head: pointer to the list-head
	27	* @len: length of the list-head, as userspace expects
	28	*/
	29	SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head,
	30	size_t, len)
	31	{
af8cc960 PZ	32	/*
	33	* The kernel knows only one size for now:
	34	*/
	35	if (unlikely(len != sizeof(*head)))
	36	return -EINVAL;
	37
	38	current->robust_list = head;
	39
	40	return 0;
	41	}
	42
	43	/**
	44	* sys_get_robust_list() - Get the robust-futex list head of a task
	45	* @pid: pid of the process [zero for current task]
	46	* @head_ptr: pointer to a list-head pointer, the kernel fills it in
	47	* @len_ptr: pointer to a length field, the kernel fills in the header size
	48	*/
	49	SYSCALL_DEFINE3(get_robust_list, int, pid,
	50	struct robust_list_head __user * __user *, head_ptr,
	51	size_t __user *, len_ptr)
	52	{
	53	struct robust_list_head __user *head;
	54	unsigned long ret;
	55	struct task_struct *p;
	56
af8cc960 PZ	57	rcu_read_lock();
	58
	59	ret = -ESRCH;
	60	if (!pid)
	61	p = current;
	62	else {
	63	p = find_task_by_vpid(pid);
	64	if (!p)
	65	goto err_unlock;
	66	}
	67
	68	ret = -EPERM;
	69	if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS))
	70	goto err_unlock;
	71
	72	head = p->robust_list;
	73	rcu_read_unlock();
	74
	75	if (put_user(sizeof(*head), len_ptr))
	76	return -EFAULT;
	77	return put_user(head, head_ptr);
	78
	79	err_unlock:
	80	rcu_read_unlock();
	81
	82	return ret;
	83	}
	84
	85	long do_futex(u32 __user uaddr, int op, u32 val, ktime_t timeout,
	86	u32 __user *uaddr2, u32 val2, u32 val3)
	87	{
	88	int cmd = op & FUTEX_CMD_MASK;
	89	unsigned int flags = 0;
	90
	91	if (!(op & FUTEX_PRIVATE_FLAG))
	92	flags \|= FLAGS_SHARED;
	93
	94	if (op & FUTEX_CLOCK_REALTIME) {
	95	flags \|= FLAGS_CLOCKRT;
	96	if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI &&
	97	cmd != FUTEX_LOCK_PI2)
	98	return -ENOSYS;
	99	}
	100
af8cc960 PZ	101	switch (cmd) {
	102	case FUTEX_WAIT:
	103	val3 = FUTEX_BITSET_MATCH_ANY;
	104	fallthrough;
	105	case FUTEX_WAIT_BITSET:
	106	return futex_wait(uaddr, flags, val, timeout, val3);
	107	case FUTEX_WAKE:
	108	val3 = FUTEX_BITSET_MATCH_ANY;
	109	fallthrough;
	110	case FUTEX_WAKE_BITSET:
	111	return futex_wake(uaddr, flags, val, val3);
	112	case FUTEX_REQUEUE:
	113	return futex_requeue(uaddr, flags, uaddr2, val, val2, NULL, 0);
	114	case FUTEX_CMP_REQUEUE:
	115	return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 0);
	116	case FUTEX_WAKE_OP:
	117	return futex_wake_op(uaddr, flags, uaddr2, val, val2, val3);
	118	case FUTEX_LOCK_PI:
	119	flags \|= FLAGS_CLOCKRT;
	120	fallthrough;
	121	case FUTEX_LOCK_PI2:
	122	return futex_lock_pi(uaddr, flags, timeout, 0);
	123	case FUTEX_UNLOCK_PI:
	124	return futex_unlock_pi(uaddr, flags);
	125	case FUTEX_TRYLOCK_PI:
	126	return futex_lock_pi(uaddr, flags, NULL, 1);
	127	case FUTEX_WAIT_REQUEUE_PI:
	128	val3 = FUTEX_BITSET_MATCH_ANY;
	129	return futex_wait_requeue_pi(uaddr, flags, val, timeout, val3,
	130	uaddr2);
	131	case FUTEX_CMP_REQUEUE_PI:
	132	return futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 1);
	133	}
	134	return -ENOSYS;
	135	}
	136
	137	static __always_inline bool futex_cmd_has_timeout(u32 cmd)
	138	{
	139	switch (cmd) {
	140	case FUTEX_WAIT:
	141	case FUTEX_LOCK_PI:
	142	case FUTEX_LOCK_PI2:
	143	case FUTEX_WAIT_BITSET:
	144	case FUTEX_WAIT_REQUEUE_PI:
	145	return true;
	146	}
	147	return false;
	148	}
	149
	150	static __always_inline int
	151	futex_init_timeout(u32 cmd, u32 op, struct timespec64 ts, ktime_t t)
	152	{
	153	if (!timespec64_valid(ts))
	154	return -EINVAL;
	155
	156	t = timespec64_to_ktime(ts);
	157	if (cmd == FUTEX_WAIT)
	158	t = ktime_add_safe(ktime_get(), t);
	159	else if (cmd != FUTEX_LOCK_PI && !(op & FUTEX_CLOCK_REALTIME))
	160	t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
	161	return 0;
	162	}
	163
	164	SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
165	const struct __kernel_timespec __user *, utime,
166	u32 __user *, uaddr2, u32, val3)
167	{
168	int ret, cmd = op & FUTEX_CMD_MASK;
169	ktime_t t, *tp = NULL;
170	struct timespec64 ts;
171
172	if (utime && futex_cmd_has_timeout(cmd)) {
173	if (unlikely(should_fail_futex(!(op & FUTEX_PRIVATE_FLAG))))
174	return -EFAULT;
175	if (get_timespec64(&ts, utime))
176	return -EFAULT;
177	ret = futex_init_timeout(cmd, op, &ts, &t);
178	if (ret)
179	return ret;
180	tp = &t;
181	}
182
183	return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
184	}
185
bf69bad3 AA	186	/* Mask of available flags for each futex in futex_waitv list */
	187	#define FUTEXV_WAITER_MASK (FUTEX_32 \| FUTEX_PRIVATE_FLAG)
	188
	189	/**
	190	* futex_parse_waitv - Parse a waitv array from userspace
	191	* @futexv: Kernel side list of waiters to be filled
	192	* @uwaitv: Userspace list to be parsed
	193	* @nr_futexes: Length of futexv
	194	*
	195	* Return: Error code on failure, 0 on success
	196	*/
	197	static int futex_parse_waitv(struct futex_vector *futexv,
	198	struct futex_waitv __user *uwaitv,
	199	unsigned int nr_futexes)
	200	{
	201	struct futex_waitv aux;
	202	unsigned int i;
	203
	204	for (i = 0; i < nr_futexes; i++) {
	205	if (copy_from_user(&aux, &uwaitv[i], sizeof(aux)))
	206	return -EFAULT;
	207
	208	if ((aux.flags & ~FUTEXV_WAITER_MASK) \|\| aux.__reserved)
	209	return -EINVAL;
	210
	211	if (!(aux.flags & FUTEX_32))
	212	return -EINVAL;
	213
	214	futexv[i].w.flags = aux.flags;
	215	futexv[i].w.val = aux.val;
	216	futexv[i].w.uaddr = aux.uaddr;
	217	futexv[i].q = futex_q_init;
	218	}
	219
	220	return 0;
	221	}
	222
	223	/**
	224	* sys_futex_waitv - Wait on a list of futexes
	225	* @waiters: List of futexes to wait on
	226	* @nr_futexes: Length of futexv
	227	* @flags: Flag for timeout (monotonic/realtime)
	228	* @timeout: Optional absolute timeout.
	229	* @clockid: Clock to be used for the timeout, realtime or monotonic.
	230	*
	231	* Given an array of `struct futex_waitv`, wait on each uaddr. The thread wakes
	232	* if a futex_wake() is performed at any uaddr. The syscall returns immediately
	233	* if any waiter has uaddr != val. timeout is an optional timeout value for
	234	* the operation. Each waiter has individual flags. The `flags` argument for
	235	* the syscall should be used solely for specifying the timeout as realtime, if
	236	* needed. Flags for private futexes, sizes, etc. should be used on the
	237	* individual flags of each waiter.
	238	*
	239	* Returns the array index of one of the woken futexes. No further information
	240	* is provided: any number of other futexes may also have been woken by the
	241	* same event, and if more than one futex was woken, the retrned index may
	242	* refer to any one of them. (It is not necessaryily the futex with the
	243	* smallest index, nor the one most recently woken, nor...)
	244	*/
	245
	246	SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters,
	247	unsigned int, nr_futexes, unsigned int, flags,
	248	struct __kernel_timespec __user *, timeout, clockid_t, clockid)
	249	{
250	struct hrtimer_sleeper to;
251	struct futex_vector *futexv;
252	struct timespec64 ts;
253	ktime_t time;
254	int ret;
255
256	/* This syscall supports no flags for now */
257	if (flags)
258	return -EINVAL;
259
260	if (!nr_futexes \|\| nr_futexes > FUTEX_WAITV_MAX \|\| !waiters)
261	return -EINVAL;
262
263	if (timeout) {
264	int flag_clkid = 0, flag_init = 0;
265
266	if (clockid == CLOCK_REALTIME) {
267	flag_clkid = FLAGS_CLOCKRT;
268	flag_init = FUTEX_CLOCK_REALTIME;
269	}
270
271	if (clockid != CLOCK_REALTIME && clockid != CLOCK_MONOTONIC)
272	return -EINVAL;
273
274	if (get_timespec64(&ts, timeout))
275	return -EFAULT;
276
277	/*
278	* Since there's no opcode for futex_waitv, use
279	* FUTEX_WAIT_BITSET that uses absolute timeout as well
280	*/
281	ret = futex_init_timeout(FUTEX_WAIT_BITSET, flag_init, &ts, &time);
282	if (ret)
283	return ret;
284
285	futex_setup_timer(&time, &to, flag_clkid, 0);
286	}
287
288	futexv = kcalloc(nr_futexes, sizeof(*futexv), GFP_KERNEL);
289	if (!futexv)
290	return -ENOMEM;
291
292	ret = futex_parse_waitv(futexv, waiters, nr_futexes);
293	if (!ret)
294	ret = futex_wait_multiple(futexv, nr_futexes, timeout ? &to : NULL);
295
296	if (timeout) {
297	hrtimer_cancel(&to.timer);
298	destroy_hrtimer_on_stack(&to.timer);
299	}
300
301	kfree(futexv);
302	return ret;
303	}
304
af8cc960 PZ	305	#ifdef CONFIG_COMPAT
	306	COMPAT_SYSCALL_DEFINE2(set_robust_list,
	307	struct compat_robust_list_head __user *, head,
	308	compat_size_t, len)
	309	{
af8cc960 PZ	310	if (unlikely(len != sizeof(*head)))
	311	return -EINVAL;
	312
	313	current->compat_robust_list = head;
	314
	315	return 0;
	316	}
	317
	318	COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid,
	319	compat_uptr_t __user *, head_ptr,
	320	compat_size_t __user *, len_ptr)
	321	{
	322	struct compat_robust_list_head __user *head;
	323	unsigned long ret;
	324	struct task_struct *p;
	325
af8cc960 PZ	326	rcu_read_lock();
	327
	328	ret = -ESRCH;
	329	if (!pid)
	330	p = current;
	331	else {
	332	p = find_task_by_vpid(pid);
	333	if (!p)
	334	goto err_unlock;
	335	}
	336
	337	ret = -EPERM;
	338	if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS))
	339	goto err_unlock;
	340
	341	head = p->compat_robust_list;
	342	rcu_read_unlock();
	343
	344	if (put_user(sizeof(*head), len_ptr))
	345	return -EFAULT;
	346	return put_user(ptr_to_compat(head), head_ptr);
	347
	348	err_unlock:
	349	rcu_read_unlock();
	350
	351	return ret;
	352	}
	353	#endif /* CONFIG_COMPAT */
	354
	355	#ifdef CONFIG_COMPAT_32BIT_TIME
	356	SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
	357	const struct old_timespec32 __user , utime, u32 __user , uaddr2,
	358	u32, val3)
	359	{
	360	int ret, cmd = op & FUTEX_CMD_MASK;
	361	ktime_t t, *tp = NULL;
	362	struct timespec64 ts;
	363
	364	if (utime && futex_cmd_has_timeout(cmd)) {
	365	if (get_old_timespec32(&ts, utime))
	366	return -EFAULT;
	367	ret = futex_init_timeout(cmd, op, &ts, &t);
	368	if (ret)
	369	return ret;
	370	tp = &t;
	371	}
	372
	373	return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
	374	}
	375	#endif /* CONFIG_COMPAT_32BIT_TIME */
	376