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 <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 } 60