1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. 4 */ 5 6 /* 7 * Support for user memory access from kernel. This will 8 * probably be inlined for performance at some point, but 9 * for ease of debug, and to a lesser degree for code size, 10 * we implement here as subroutines. 11 */ 12 #include <linux/types.h> 13 #include <linux/uaccess.h> 14 #include <linux/pgtable.h> 15 16 /* 17 * For clear_user(), exploit previously defined copy_to_user function 18 * and the fact that we've got a handy zero page defined in kernel/head.S 19 * 20 * dczero here would be even faster. 21 */ 22 __kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count) 23 { 24 long uncleared; 25 26 while (count > PAGE_SIZE) { 27 uncleared = raw_copy_to_user(dest, &empty_zero_page, PAGE_SIZE); 28 if (uncleared) 29 return count - (PAGE_SIZE - uncleared); 30 count -= PAGE_SIZE; 31 dest += PAGE_SIZE; 32 } 33 if (count) 34 count = raw_copy_to_user(dest, &empty_zero_page, count); 35 36 return count; 37 } 38