| 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 | } |