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7567746e RK |
1 | /* |
2 | * Copyright (c) 2010-2011, Code Aurora Forum. 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 <asm/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 = __copy_to_user_hexagon(dest, &empty_zero_page, | |
41 | PAGE_SIZE); | |
42 | if (uncleared) | |
43 | return count - (PAGE_SIZE - uncleared); | |
44 | count -= PAGE_SIZE; | |
45 | dest += PAGE_SIZE; | |
46 | } | |
47 | if (count) | |
48 | count = __copy_to_user_hexagon(dest, &empty_zero_page, count); | |
49 | ||
50 | return count; | |
51 | } | |
52 | ||
53 | unsigned long clear_user_hexagon(void __user *dest, unsigned long count) | |
54 | { | |
55 | if (!access_ok(VERIFY_WRITE, dest, count)) | |
56 | return count; | |
57 | else | |
58 | return __clear_user_hexagon(dest, count); | |
59 | } |