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