1/*
 2 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
 3 *
 4 * This program is free software; you can redistribute it and/or modify
 5 * it under the terms of the GNU General Public License version 2 and
 6 * only version 2 as published by the Free Software Foundation.
 7 *
 8 * This program is distributed in the hope that it will be useful,
 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
16 * 02110-1301, USA.
17 */
18
19/*
20 * Support for user memory access from kernel.  This will
21 * probably be inlined for performance at some point, but
22 * for ease of debug, and to a lesser degree for code size,
23 * we implement here as subroutines.
24 */
25#include <linux/types.h>
26#include <linux/uaccess.h>
27#include <asm/pgtable.h>
28
29/*
30 * For clear_user(), exploit previously defined copy_to_user function
31 * and the fact that we've got a handy zero page defined in kernel/head.S
32 *
33 * dczero here would be even faster.
34 */
35__kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count)
36{
37	long uncleared;
38
39	while (count > PAGE_SIZE) {
40		uncleared = raw_copy_to_user(dest, &empty_zero_page, PAGE_SIZE);
41		if (uncleared)
42			return count - (PAGE_SIZE - uncleared);
43		count -= PAGE_SIZE;
44		dest += PAGE_SIZE;
45	}
46	if (count)
47		count = raw_copy_to_user(dest, &empty_zero_page, count);
48
49	return count;
50}
51
52unsigned long clear_user_hexagon(void __user *dest, unsigned long count)
53{
54	if (!access_ok(VERIFY_WRITE, dest, count))
55		return count;
56	else
57		return __clear_user_hexagon(dest, count);
58}