1 /* SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause) */ 2 #ifndef LIBFDT_INTERNAL_H 3 #define LIBFDT_INTERNAL_H 4 /* 5 * libfdt - Flat Device Tree manipulation 6 * Copyright (C) 2006 David Gibson, IBM Corporation. 7 */ 8 #include <fdt.h> 9 10 #define FDT_ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1)) 11 #define FDT_TAGALIGN(x) (FDT_ALIGN((x), FDT_TAGSIZE)) 12 13 int32_t fdt_ro_probe_(const void *fdt); 14 #define FDT_RO_PROBE(fdt) \ 15 { \ 16 int32_t totalsize_; \ 17 if ((totalsize_ = fdt_ro_probe_(fdt)) < 0) \ 18 return totalsize_; \ 19 } 20 21 int fdt_check_node_offset_(const void *fdt, int offset); 22 int fdt_check_prop_offset_(const void *fdt, int offset); 23 const char *fdt_find_string_(const char *strtab, int tabsize, const char *s); 24 int fdt_node_end_offset_(void *fdt, int nodeoffset); 25 26 static inline const void *fdt_offset_ptr_(const void *fdt, int offset) 27 { 28 return (const char *)fdt + fdt_off_dt_struct(fdt) + offset; 29 } 30 31 static inline void *fdt_offset_ptr_w_(void *fdt, int offset) 32 { 33 return (void *)(uintptr_t)fdt_offset_ptr_(fdt, offset); 34 } 35 36 static inline const struct fdt_reserve_entry *fdt_mem_rsv_(const void *fdt, int n) 37 { 38 const struct fdt_reserve_entry *rsv_table = 39 (const struct fdt_reserve_entry *) 40 ((const char *)fdt + fdt_off_mem_rsvmap(fdt)); 41 42 return rsv_table + n; 43 } 44 static inline struct fdt_reserve_entry *fdt_mem_rsv_w_(void *fdt, int n) 45 { 46 return (void *)(uintptr_t)fdt_mem_rsv_(fdt, n); 47 } 48 49 #define FDT_SW_MAGIC (~FDT_MAGIC) 50 51 /**********************************************************************/ 52 /* Checking controls */ 53 /**********************************************************************/ 54 55 #ifndef FDT_ASSUME_MASK 56 #define FDT_ASSUME_MASK 0 57 #endif 58 59 /* 60 * Defines assumptions which can be enabled. Each of these can be enabled 61 * individually. For maximum safety, don't enable any assumptions! 62 * 63 * For minimal code size and no safety, use ASSUME_PERFECT at your own risk. 64 * You should have another method of validating the device tree, such as a 65 * signature or hash check before using libfdt. 66 * 67 * For situations where security is not a concern it may be safe to enable 68 * ASSUME_SANE. 69 */ 70 enum { 71 /* 72 * This does essentially no checks. Only the latest device-tree 73 * version is correctly handled. Inconsistencies or errors in the device 74 * tree may cause undefined behaviour or crashes. Invalid parameters 75 * passed to libfdt may do the same. 76 * 77 * If an error occurs when modifying the tree it may leave the tree in 78 * an intermediate (but valid) state. As an example, adding a property 79 * where there is insufficient space may result in the property name 80 * being added to the string table even though the property itself is 81 * not added to the struct section. 82 * 83 * Only use this if you have a fully validated device tree with 84 * the latest supported version and wish to minimise code size. 85 */ 86 ASSUME_PERFECT = 0xff, 87 88 /* 89 * This assumes that the device tree is sane. i.e. header metadata 90 * and basic hierarchy are correct. 91 * 92 * With this assumption enabled, normal device trees produced by libfdt 93 * and the compiler should be handled safely. Malicious device trees and 94 * complete garbage may cause libfdt to behave badly or crash. Truncated 95 * device trees (e.g. those only partially loaded) can also cause 96 * problems. 97 * 98 * Note: Only checks that relate exclusively to the device tree itself 99 * (not the parameters passed to libfdt) are disabled by this 100 * assumption. This includes checking headers, tags and the like. 101 */ 102 ASSUME_VALID_DTB = 1 << 0, 103 104 /* 105 * This builds on ASSUME_VALID_DTB and further assumes that libfdt 106 * functions are called with valid parameters, i.e. not trigger 107 * FDT_ERR_BADOFFSET or offsets that are out of bounds. It disables any 108 * extensive checking of parameters and the device tree, making various 109 * assumptions about correctness. 110 * 111 * It doesn't make sense to enable this assumption unless 112 * ASSUME_VALID_DTB is also enabled. 113 */ 114 ASSUME_VALID_INPUT = 1 << 1, 115 116 /* 117 * This disables checks for device-tree version and removes all code 118 * which handles older versions. 119 * 120 * Only enable this if you know you have a device tree with the latest 121 * version. 122 */ 123 ASSUME_LATEST = 1 << 2, 124 125 /* 126 * This assumes that it is OK for a failed addition to the device tree, 127 * due to lack of space or some other problem, to skip any rollback 128 * steps (such as dropping the property name from the string table). 129 * This is safe to enable in most circumstances, even though it may 130 * leave the tree in a sub-optimal state. 131 */ 132 ASSUME_NO_ROLLBACK = 1 << 3, 133 134 /* 135 * This assumes that the device tree components appear in a 'convenient' 136 * order, i.e. the memory reservation block first, then the structure 137 * block and finally the string block. 138 * 139 * This order is not specified by the device-tree specification, 140 * but is expected by libfdt. The device-tree compiler always created 141 * device trees with this order. 142 * 143 * This assumption disables a check in fdt_open_into() and removes the 144 * ability to fix the problem there. This is safe if you know that the 145 * device tree is correctly ordered. See fdt_blocks_misordered_(). 146 */ 147 ASSUME_LIBFDT_ORDER = 1 << 4, 148 149 /* 150 * This assumes that libfdt itself does not have any internal bugs. It 151 * drops certain checks that should never be needed unless libfdt has an 152 * undiscovered bug. 153 * 154 * This can generally be considered safe to enable. 155 */ 156 ASSUME_LIBFDT_FLAWLESS = 1 << 5, 157 }; 158 159 /** 160 * can_assume_() - check if a particular assumption is enabled 161 * 162 * @mask: Mask to check (ASSUME_...) 163 * @return true if that assumption is enabled, else false 164 */ 165 static inline bool can_assume_(int mask) 166 { 167 return FDT_ASSUME_MASK & mask; 168 } 169 170 /** helper macros for checking assumptions */ 171 #define can_assume(_assume) can_assume_(ASSUME_ ## _assume) 172 173 #endif /* LIBFDT_INTERNAL_H */ 174