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