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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 : 6752 : static inline const void *fdt_offset_ptr_(const void *fdt, int offset)
27 : : {
28 : 6752 : return (const char *)fdt + fdt_off_dt_struct(fdt) + offset;
29 : : }
30 : :
31 : 1853 : static inline void *fdt_offset_ptr_w_(void *fdt, int offset)
32 : : {
33 : 1853 : return (void *)(uintptr_t)fdt_offset_ptr_(fdt, offset);
34 : : }
35 : :
36 : 0 : static inline const struct fdt_reserve_entry *fdt_mem_rsv_(const void *fdt, int n)
37 : : {
38 : 0 : const struct fdt_reserve_entry *rsv_table =
39 : : (const struct fdt_reserve_entry *)
40 : 0 : ((const char *)fdt + fdt_off_mem_rsvmap(fdt));
41 : :
42 : 0 : 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 : 0 : static inline uint32_t fdt32_ld_(const fdt32_t *p)
59 : : {
60 : 0 : return fdt32_to_cpu(*p);
61 : : }
62 : :
63 : 0 : static inline uint64_t fdt64_ld_(const fdt64_t *p)
64 : : {
65 : 0 : 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 : 14878 : static inline bool can_assume_(int mask)
185 : : {
186 : 14878 : 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 */
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