/* * 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/futex.h> #include <asm/uaccess.h> /* * 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, *pending;	compat_uptr_t uentry, upending;	unsigned int limit = ROBUST_LIST_LIMIT;	compat_long_t futex_offset; 	/*	 * Fetch the list head (which was registered earlier, via	 * sys_set_robust_list()):	 */	if (get_user(uentry, &head->list.next))		return;	entry = compat_ptr(uentry);	/*	 * 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 (get_user(upending, &head->list_op_pending))		return;	pending = compat_ptr(upending);	if (upending)		handle_futex_death((void *)pending + futex_offset, curr); 	while (compat_ptr(uentry) != &head->list) {		/*		 * A pending lock might already be on the list, so		 * dont process it twice:		 */		if (entry != pending)			if (handle_futex_death((void *)entry + futex_offset,						curr))				return; 		/*		 * Fetch the next entry in the list:		 */		if (get_user(uentry, (compat_uptr_t *)&entry->next))			return;		entry = compat_ptr(uentry);		/*		 * Avoid excessively long or circular lists:		 */		if (!--limit)			break; 		cond_resched();	}} asmlinkage longcompat_sys_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;} asmlinkage longcompat_sys_get_robust_list(int pid, compat_uptr_t *head_ptr,			   compat_size_t __user *len_ptr){	struct compat_robust_list_head *head;	unsigned long ret; 	if (!pid)		head = current->compat_robust_list;	else {		struct task_struct *p; 		ret = -ESRCH;		read_lock(&tasklist_lock);		p = find_task_by_pid(pid);		if (!p)			goto err_unlock;		ret = -EPERM;		if ((current->euid != p->euid) && (current->euid != p->uid) &&				!capable(CAP_SYS_PTRACE))			goto err_unlock;		head = p->compat_robust_list;		read_unlock(&tasklist_lock);	} 	if (put_user(sizeof(*head), len_ptr))		return -EFAULT;	return put_user(ptr_to_compat(head), head_ptr); err_unlock:	read_unlock(&tasklist_lock); 	return ret;} asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val,		struct compat_timespec __user *utime, u32 __user *uaddr2,		u32 val3){	struct timespec t;	unsigned long timeout = MAX_SCHEDULE_TIMEOUT;	int val2 = 0; 	if (utime && (op == FUTEX_WAIT)) {		if (get_compat_timespec(&t, utime))			return -EFAULT;		if (!timespec_valid(&t))			return -EINVAL;		timeout = timespec_to_jiffies(&t) + 1;	}	if (op >= FUTEX_REQUEUE)		val2 = (int) (unsigned long) utime; 	return do_futex((unsigned long)uaddr, op, val, timeout,			(unsigned long)uaddr2, val2, val3);}