/* * linux/kernel/futex_compat.c * * Futex compatibililty routines. * * Copyright 2006, Red Hat, Inc., Ingo Molnar */ #include <linux/linkage.h>#include <linux/compat.h>#include <linux/nsproxy.h>#include <linux/futex.h>#include <linux/ptrace.h>#include <linux/syscalls.h> #include <linux/uaccess.h>  /* * Fetch a robust-list pointer. Bit 0 signals PI futexes: */static inline intfetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry,		   compat_uptr_t __user *head, unsigned int *pi){	if (get_user(*uentry, head))		return -EFAULT; 	*entry = compat_ptr((*uentry) & ~1);	*pi = (unsigned int)(*uentry) & 1; 	return 0;} static void __user *futex_uaddr(struct robust_list __user *entry,				compat_long_t futex_offset){	compat_uptr_t base = ptr_to_compat(entry);	void __user *uaddr = compat_ptr(base + futex_offset); 	return uaddr;} /* * Walk curr->robust_list (very carefully, it's a userspace list!) * and mark any locks found there dead, and notify any waiters. * * We silently return on any sign of list-walking problem. */void compat_exit_robust_list(struct task_struct *curr){	struct compat_robust_list_head __user *head = curr->compat_robust_list;	struct robust_list __user *entry, *next_entry, *pending;	unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;	unsigned int uninitialized_var(next_pi);	compat_uptr_t uentry, next_uentry, upending;	compat_long_t futex_offset;	int rc; 	if (!futex_cmpxchg_enabled)		return; 	/*	 * Fetch the list head (which was registered earlier, via	 * sys_set_robust_list()):	 */	if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi))		return;	/*	 * Fetch the relative futex offset:	 */	if (get_user(futex_offset, &head->futex_offset))		return;	/*	 * Fetch any possibly pending lock-add first, and handle it	 * if it exists:	 */	if (fetch_robust_entry(&upending, &pending,			       &head->list_op_pending, &pip))		return; 	next_entry = NULL;	/* avoid warning with gcc */	while (entry != (struct robust_list __user *) &head->list) {		/*		 * Fetch the next entry in the list before calling		 * handle_futex_death:		 */		rc = fetch_robust_entry(&next_uentry, &next_entry,			(compat_uptr_t __user *)&entry->next, &next_pi);		/*		 * A pending lock might already be on the list, so		 * dont process it twice:		 */		if (entry != pending) {			void __user *uaddr = futex_uaddr(entry, futex_offset); 			if (handle_futex_death(uaddr, curr, pi))				return;		}		if (rc)			return;		uentry = next_uentry;		entry = next_entry;		pi = next_pi;		/*		 * Avoid excessively long or circular lists:		 */		if (!--limit)			break; 		cond_resched();	}	if (pending) {		void __user *uaddr = futex_uaddr(pending, futex_offset); 		handle_futex_death(uaddr, curr, pip);	}} COMPAT_SYSCALL_DEFINE2(set_robust_list,		struct compat_robust_list_head __user *, head,		compat_size_t, len){	if (!futex_cmpxchg_enabled)		return -ENOSYS; 	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; 	if (!futex_cmpxchg_enabled)		return -ENOSYS; 	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;} COMPAT_SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,		struct compat_timespec __user *, utime, u32 __user *, uaddr2,		u32, val3){	struct timespec ts;	ktime_t t, *tp = NULL;	int val2 = 0;	int cmd = op & FUTEX_CMD_MASK; 	if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||		      cmd == FUTEX_WAIT_BITSET ||		      cmd == FUTEX_WAIT_REQUEUE_PI)) {		if (compat_get_timespec(&ts, utime))			return -EFAULT;		if (!timespec_valid(&ts))			return -EINVAL; 		t = timespec_to_ktime(ts);		if (cmd == FUTEX_WAIT)			t = ktime_add_safe(ktime_get(), t);		tp = &t;	}	if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||	    cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)		val2 = (int) (unsigned long) utime; 	return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);}