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| 1 | +/* SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause) */ |
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1 | 2 | #ifndef LIBFDT_INTERNAL_H |
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2 | 3 | #define LIBFDT_INTERNAL_H |
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3 | 4 | /* |
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4 | 5 | * libfdt - Flat Device Tree manipulation |
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5 | 6 | * Copyright (C) 2006 David Gibson, IBM Corporation. |
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6 | | - * |
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7 | | - * libfdt is dual licensed: you can use it either under the terms of |
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8 | | - * the GPL, or the BSD license, at your option. |
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9 | | - * |
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10 | | - * a) This library is free software; you can redistribute it and/or |
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11 | | - * modify it under the terms of the GNU General Public License as |
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12 | | - * published by the Free Software Foundation; either version 2 of the |
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13 | | - * License, or (at your option) any later version. |
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14 | | - * |
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15 | | - * This library is distributed in the hope that it will be useful, |
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16 | | - * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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17 | | - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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18 | | - * GNU General Public License for more details. |
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19 | | - * |
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20 | | - * You should have received a copy of the GNU General Public |
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21 | | - * License along with this library; if not, write to the Free |
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22 | | - * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, |
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23 | | - * MA 02110-1301 USA |
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24 | | - * |
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25 | | - * Alternatively, |
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26 | | - * |
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27 | | - * b) Redistribution and use in source and binary forms, with or |
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28 | | - * without modification, are permitted provided that the following |
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29 | | - * conditions are met: |
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30 | | - * |
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31 | | - * 1. Redistributions of source code must retain the above |
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32 | | - * copyright notice, this list of conditions and the following |
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33 | | - * disclaimer. |
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34 | | - * 2. Redistributions in binary form must reproduce the above |
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35 | | - * copyright notice, this list of conditions and the following |
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36 | | - * disclaimer in the documentation and/or other materials |
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37 | | - * provided with the distribution. |
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38 | | - * |
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39 | | - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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40 | | - * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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41 | | - * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
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42 | | - * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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43 | | - * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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44 | | - * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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45 | | - * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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46 | | - * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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47 | | - * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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48 | | - * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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49 | | - * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
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50 | | - * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, |
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51 | | - * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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52 | 7 | */ |
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53 | 8 | #include <fdt.h> |
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54 | 9 | |
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55 | 10 | #define FDT_ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1)) |
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56 | 11 | #define FDT_TAGALIGN(x) (FDT_ALIGN((x), FDT_TAGSIZE)) |
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57 | 12 | |
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58 | | -#define FDT_CHECK_HEADER(fdt) \ |
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59 | | - { \ |
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60 | | - int err_; \ |
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61 | | - if ((err_ = fdt_check_header(fdt)) != 0) \ |
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62 | | - return err_; \ |
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| 13 | +int32_t fdt_ro_probe_(const void *fdt); |
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| 14 | +#define FDT_RO_PROBE(fdt) \ |
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| 15 | + { \ |
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| 16 | + int32_t totalsize_; \ |
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| 17 | + if ((totalsize_ = fdt_ro_probe_(fdt)) < 0) \ |
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| 18 | + return totalsize_; \ |
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63 | 19 | } |
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64 | 20 | |
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65 | 21 | int fdt_check_node_offset_(const void *fdt, int offset); |
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.. | .. |
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92 | 48 | |
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93 | 49 | #define FDT_SW_MAGIC (~FDT_MAGIC) |
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94 | 50 | |
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| 51 | +/**********************************************************************/ |
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| 52 | +/* Checking controls */ |
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| 53 | +/**********************************************************************/ |
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| 54 | + |
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| 55 | +#ifndef FDT_ASSUME_MASK |
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| 56 | +#define FDT_ASSUME_MASK 0 |
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| 57 | +#endif |
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| 58 | + |
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| 59 | +/* |
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| 60 | + * Defines assumptions which can be enabled. Each of these can be enabled |
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| 61 | + * individually. For maximum safety, don't enable any assumptions! |
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| 62 | + * |
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| 63 | + * For minimal code size and no safety, use ASSUME_PERFECT at your own risk. |
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| 64 | + * You should have another method of validating the device tree, such as a |
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| 65 | + * signature or hash check before using libfdt. |
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| 66 | + * |
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| 67 | + * For situations where security is not a concern it may be safe to enable |
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| 68 | + * ASSUME_SANE. |
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| 69 | + */ |
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| 70 | +enum { |
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| 71 | + /* |
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| 72 | + * This does essentially no checks. Only the latest device-tree |
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| 73 | + * version is correctly handled. Inconsistencies or errors in the device |
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| 74 | + * tree may cause undefined behaviour or crashes. Invalid parameters |
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| 75 | + * passed to libfdt may do the same. |
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| 76 | + * |
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| 77 | + * If an error occurs when modifying the tree it may leave the tree in |
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| 78 | + * an intermediate (but valid) state. As an example, adding a property |
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| 79 | + * where there is insufficient space may result in the property name |
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| 80 | + * being added to the string table even though the property itself is |
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| 81 | + * not added to the struct section. |
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| 82 | + * |
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| 83 | + * Only use this if you have a fully validated device tree with |
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| 84 | + * the latest supported version and wish to minimise code size. |
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| 85 | + */ |
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| 86 | + ASSUME_PERFECT = 0xff, |
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| 87 | + |
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| 88 | + /* |
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| 89 | + * This assumes that the device tree is sane. i.e. header metadata |
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| 90 | + * and basic hierarchy are correct. |
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| 91 | + * |
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| 92 | + * With this assumption enabled, normal device trees produced by libfdt |
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| 93 | + * and the compiler should be handled safely. Malicious device trees and |
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| 94 | + * complete garbage may cause libfdt to behave badly or crash. Truncated |
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| 95 | + * device trees (e.g. those only partially loaded) can also cause |
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| 96 | + * problems. |
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| 97 | + * |
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| 98 | + * Note: Only checks that relate exclusively to the device tree itself |
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| 99 | + * (not the parameters passed to libfdt) are disabled by this |
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| 100 | + * assumption. This includes checking headers, tags and the like. |
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| 101 | + */ |
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| 102 | + ASSUME_VALID_DTB = 1 << 0, |
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| 103 | + |
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| 104 | + /* |
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| 105 | + * This builds on ASSUME_VALID_DTB and further assumes that libfdt |
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| 106 | + * functions are called with valid parameters, i.e. not trigger |
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| 107 | + * FDT_ERR_BADOFFSET or offsets that are out of bounds. It disables any |
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| 108 | + * extensive checking of parameters and the device tree, making various |
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| 109 | + * assumptions about correctness. |
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| 110 | + * |
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| 111 | + * It doesn't make sense to enable this assumption unless |
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| 112 | + * ASSUME_VALID_DTB is also enabled. |
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| 113 | + */ |
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| 114 | + ASSUME_VALID_INPUT = 1 << 1, |
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| 115 | + |
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| 116 | + /* |
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| 117 | + * This disables checks for device-tree version and removes all code |
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| 118 | + * which handles older versions. |
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| 119 | + * |
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| 120 | + * Only enable this if you know you have a device tree with the latest |
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| 121 | + * version. |
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| 122 | + */ |
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| 123 | + ASSUME_LATEST = 1 << 2, |
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| 124 | + |
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| 125 | + /* |
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| 126 | + * This assumes that it is OK for a failed addition to the device tree, |
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| 127 | + * due to lack of space or some other problem, to skip any rollback |
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| 128 | + * steps (such as dropping the property name from the string table). |
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| 129 | + * This is safe to enable in most circumstances, even though it may |
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| 130 | + * leave the tree in a sub-optimal state. |
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| 131 | + */ |
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| 132 | + ASSUME_NO_ROLLBACK = 1 << 3, |
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| 133 | + |
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| 134 | + /* |
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| 135 | + * This assumes that the device tree components appear in a 'convenient' |
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| 136 | + * order, i.e. the memory reservation block first, then the structure |
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| 137 | + * block and finally the string block. |
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| 138 | + * |
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| 139 | + * This order is not specified by the device-tree specification, |
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| 140 | + * but is expected by libfdt. The device-tree compiler always created |
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| 141 | + * device trees with this order. |
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| 142 | + * |
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| 143 | + * This assumption disables a check in fdt_open_into() and removes the |
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| 144 | + * ability to fix the problem there. This is safe if you know that the |
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| 145 | + * device tree is correctly ordered. See fdt_blocks_misordered_(). |
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| 146 | + */ |
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| 147 | + ASSUME_LIBFDT_ORDER = 1 << 4, |
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| 148 | + |
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| 149 | + /* |
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| 150 | + * This assumes that libfdt itself does not have any internal bugs. It |
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| 151 | + * drops certain checks that should never be needed unless libfdt has an |
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| 152 | + * undiscovered bug. |
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| 153 | + * |
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| 154 | + * This can generally be considered safe to enable. |
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| 155 | + */ |
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| 156 | + ASSUME_LIBFDT_FLAWLESS = 1 << 5, |
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| 157 | +}; |
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| 158 | + |
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| 159 | +/** |
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| 160 | + * can_assume_() - check if a particular assumption is enabled |
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| 161 | + * |
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| 162 | + * @mask: Mask to check (ASSUME_...) |
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| 163 | + * @return true if that assumption is enabled, else false |
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| 164 | + */ |
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| 165 | +static inline bool can_assume_(int mask) |
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| 166 | +{ |
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| 167 | + return FDT_ASSUME_MASK & mask; |
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| 168 | +} |
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| 169 | + |
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| 170 | +/** helper macros for checking assumptions */ |
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| 171 | +#define can_assume(_assume) can_assume_(ASSUME_ ## _assume) |
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| 172 | + |
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95 | 173 | #endif /* LIBFDT_INTERNAL_H */ |
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