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 | /* |
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 | */ |
58 | static inline uint32_t fdt32_ld_(const fdt32_t *p) |
59 | { |
60 | return fdt32_to_cpu(*p); |
61 | } |
62 | |
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 | */ |
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 | |