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 if (!can_assume(VALID_DTB)) { \ 17 int32_t totalsize_; \ 18 if ((totalsize_ = fdt_ro_probe_(fdt)) < 0) \ 19 return totalsize_; \ 20 } \ 21 } 22 23 int fdt_check_node_offset_(const void *fdt, int offset); 24 int fdt_check_prop_offset_(const void *fdt, int offset); 25 26 const char *fdt_find_string_len_(const char *strtab, int tabsize, const char *s, 27 int s_len); 28 static inline const char *fdt_find_string_(const char *strtab, int tabsize, 29 const char *s) 30 { 31 return fdt_find_string_len_(strtab, tabsize, s, strlen(s)); 32 } 33 34 int fdt_node_end_offset_(void *fdt, int nodeoffset); 35 36 static inline const void *fdt_offset_ptr_(const void *fdt, int offset) 37 { 38 return (const char *)fdt + fdt_off_dt_struct(fdt) + offset; 39 } 40 41 static inline void *fdt_offset_ptr_w_(void *fdt, int offset) 42 { 43 return (void *)(uintptr_t)fdt_offset_ptr_(fdt, offset); 44 } 45 46 static inline const struct fdt_reserve_entry *fdt_mem_rsv_(const void *fdt, int n) 47 { 48 const struct fdt_reserve_entry *rsv_table = 49 (const struct fdt_reserve_entry *) 50 ((const char *)fdt + fdt_off_mem_rsvmap(fdt)); 51 52 return rsv_table + n; 53 } 54 static inline struct fdt_reserve_entry *fdt_mem_rsv_w_(void *fdt, int n) 55 { 56 return (void *)(uintptr_t)fdt_mem_rsv_(fdt, n); 57 } 58 59 /* 60 * Internal helpers to access structural elements of the device tree 61 * blob (rather than for example reading integers from within property 62 * values). We assume that we are either given a naturally aligned 63 * address for the platform or if we are not, we are on a platform 64 * where unaligned memory reads will be handled in a graceful manner. 65 * If not the external helpers fdtXX_ld() from libfdt.h can be used 66 * instead. 67 */ 68 static inline uint32_t fdt32_ld_(const fdt32_t *p) 69 { 70 return fdt32_to_cpu(*p); 71 } 72 73 static inline uint64_t fdt64_ld_(const fdt64_t *p) 74 { 75 return fdt64_to_cpu(*p); 76 } 77 78 #define FDT_SW_MAGIC (~FDT_MAGIC) 79 80 /**********************************************************************/ 81 /* Checking controls */ 82 /**********************************************************************/ 83 84 #ifndef FDT_ASSUME_MASK 85 #define FDT_ASSUME_MASK 0 86 #endif 87 88 /* 89 * Defines assumptions which can be enabled. Each of these can be enabled 90 * individually. For maximum safety, don't enable any assumptions! 91 * 92 * For minimal code size and no safety, use ASSUME_PERFECT at your own risk. 93 * You should have another method of validating the device tree, such as a 94 * signature or hash check before using libfdt. 95 * 96 * For situations where security is not a concern it may be safe to enable 97 * ASSUME_PERFECT. 98 */ 99 enum { 100 /* 101 * This does essentially no checks. Only the latest device-tree 102 * version is correctly handled. Inconsistencies or errors in the device 103 * tree may cause undefined behaviour or crashes. Invalid parameters 104 * passed to libfdt may do the same. 105 * 106 * If an error occurs when modifying the tree it may leave the tree in 107 * an intermediate (but valid) state. As an example, adding a property 108 * where there is insufficient space may result in the property name 109 * being added to the string table even though the property itself is 110 * not added to the struct section. 111 * 112 * Only use this if you have a fully validated device tree with 113 * the latest supported version and wish to minimise code size. 114 */ 115 ASSUME_PERFECT = 0xff, 116 117 /* 118 * This assumes that the device tree is sane. i.e. header metadata 119 * and basic hierarchy are correct. 120 * 121 * With this assumption enabled, normal device trees produced by libfdt 122 * and the compiler should be handled safely. Malicious device trees and 123 * complete garbage may cause libfdt to behave badly or crash. Truncated 124 * device trees (e.g. those only partially loaded) can also cause 125 * problems. 126 * 127 * Note: Only checks that relate exclusively to the device tree itself 128 * (not the parameters passed to libfdt) are disabled by this 129 * assumption. This includes checking headers, tags and the like. 130 */ 131 ASSUME_VALID_DTB = 1 << 0, 132 133 /* 134 * This builds on ASSUME_VALID_DTB and further assumes that libfdt 135 * functions are called with valid parameters, i.e. not trigger 136 * FDT_ERR_BADOFFSET or offsets that are out of bounds. It disables any 137 * extensive checking of parameters and the device tree, making various 138 * assumptions about correctness. 139 * 140 * It doesn't make sense to enable this assumption unless 141 * ASSUME_VALID_DTB is also enabled. 142 */ 143 ASSUME_VALID_INPUT = 1 << 1, 144 145 /* 146 * This disables checks for device-tree version and removes all code 147 * which handles older versions. 148 * 149 * Only enable this if you know you have a device tree with the latest 150 * version. 151 */ 152 ASSUME_LATEST = 1 << 2, 153 154 /* 155 * This assumes that it is OK for a failed addition to the device tree, 156 * due to lack of space or some other problem, to skip any rollback 157 * steps (such as dropping the property name from the string table). 158 * This is safe to enable in most circumstances, even though it may 159 * leave the tree in a sub-optimal state. 160 */ 161 ASSUME_NO_ROLLBACK = 1 << 3, 162 163 /* 164 * This assumes that the device tree components appear in a 'convenient' 165 * order, i.e. the memory reservation block first, then the structure 166 * block and finally the string block. 167 * 168 * This order is not specified by the device-tree specification, 169 * but is expected by libfdt. The device-tree compiler always created 170 * device trees with this order. 171 * 172 * This assumption disables a check in fdt_open_into() and removes the 173 * ability to fix the problem there. This is safe if you know that the 174 * device tree is correctly ordered. See fdt_blocks_misordered_(). 175 */ 176 ASSUME_LIBFDT_ORDER = 1 << 4, 177 178 /* 179 * This assumes that libfdt itself does not have any internal bugs. It 180 * drops certain checks that should never be needed unless libfdt has an 181 * undiscovered bug. 182 * 183 * This can generally be considered safe to enable. 184 */ 185 ASSUME_LIBFDT_FLAWLESS = 1 << 5, 186 }; 187 188 /** 189 * can_assume_() - check if a particular assumption is enabled 190 * 191 * @mask: Mask to check (ASSUME_...) 192 * @return true if that assumption is enabled, else false 193 */ 194 static inline bool can_assume_(int mask) 195 { 196 return FDT_ASSUME_MASK & mask; 197 } 198 199 /** helper macros for checking assumptions */ 200 #define can_assume(_assume) can_assume_(ASSUME_ ## _assume) 201 202 #endif /* LIBFDT_INTERNAL_H */ 203