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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
13int32_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
21int fdt_check_node_offset_(const void *fdt, int offset);
22int fdt_check_prop_offset_(const void *fdt, int offset);
23
24const char *fdt_find_string_len_(const char *strtab, int tabsize, const char *s,
25 int s_len);
26static inline const char *fdt_find_string_(const char *strtab, int tabsize,
27 const char *s)
28{
29 return fdt_find_string_len_(strtab, tabsize, s, strlen(s));
30}
31
32int fdt_node_end_offset_(void *fdt, int nodeoffset);
33
34static inline const void *fdt_offset_ptr_(const void *fdt, int offset)
35{
36 return (const char *)fdt + fdt_off_dt_struct(fdt) + offset;
37}
38
39static inline void *fdt_offset_ptr_w_(void *fdt, int offset)
40{
41 return (void *)(uintptr_t)fdt_offset_ptr_(fdt, offset);
42}
43
44static inline const struct fdt_reserve_entry *fdt_mem_rsv_(const void *fdt, int n)
45{
46 const struct fdt_reserve_entry *rsv_table =
47 (const struct fdt_reserve_entry *)
48 ((const char *)fdt + fdt_off_mem_rsvmap(fdt));
49
50 return rsv_table + n;
51}
52static inline struct fdt_reserve_entry *fdt_mem_rsv_w_(void *fdt, int n)
53{
54 return (void *)(uintptr_t)fdt_mem_rsv_(fdt, n);
55}
56
57/*
58 * Internal helpers to access structural elements of the device tree
59 * blob (rather than for example reading integers from within property
60 * values). We assume that we are either given a naturally aligned
61 * address for the platform or if we are not, we are on a platform
62 * where unaligned memory reads will be handled in a graceful manner.
63 * If not the external helpers fdtXX_ld() from libfdt.h can be used
64 * instead.
65 */
66static inline uint32_t fdt32_ld_(const fdt32_t *p)
67{
68 return fdt32_to_cpu(*p);
69}
70
71static inline uint64_t fdt64_ld_(const fdt64_t *p)
72{
73 return fdt64_to_cpu(*p);
74}
75
76#define FDT_SW_MAGIC (~FDT_MAGIC)
77
78/**********************************************************************/
79/* Checking controls */
80/**********************************************************************/
81
82#ifndef FDT_ASSUME_MASK
83#define FDT_ASSUME_MASK 0
84#endif
85
86/*
87 * Defines assumptions which can be enabled. Each of these can be enabled
88 * individually. For maximum safety, don't enable any assumptions!
89 *
90 * For minimal code size and no safety, use ASSUME_PERFECT at your own risk.
91 * You should have another method of validating the device tree, such as a
92 * signature or hash check before using libfdt.
93 *
94 * For situations where security is not a concern it may be safe to enable
95 * ASSUME_SANE.
96 */
97enum {
98 /*
99 * This does essentially no checks. Only the latest device-tree
100 * version is correctly handled. Inconsistencies or errors in the device
101 * tree may cause undefined behaviour or crashes. Invalid parameters
102 * passed to libfdt may do the same.
103 *
104 * If an error occurs when modifying the tree it may leave the tree in
105 * an intermediate (but valid) state. As an example, adding a property
106 * where there is insufficient space may result in the property name
107 * being added to the string table even though the property itself is
108 * not added to the struct section.
109 *
110 * Only use this if you have a fully validated device tree with
111 * the latest supported version and wish to minimise code size.
112 */
113 ASSUME_PERFECT = 0xff,
114
115 /*
116 * This assumes that the device tree is sane. i.e. header metadata
117 * and basic hierarchy are correct.
118 *
119 * With this assumption enabled, normal device trees produced by libfdt
120 * and the compiler should be handled safely. Malicious device trees and
121 * complete garbage may cause libfdt to behave badly or crash. Truncated
122 * device trees (e.g. those only partially loaded) can also cause
123 * problems.
124 *
125 * Note: Only checks that relate exclusively to the device tree itself
126 * (not the parameters passed to libfdt) are disabled by this
127 * assumption. This includes checking headers, tags and the like.
128 */
129 ASSUME_VALID_DTB = 1 << 0,
130
131 /*
132 * This builds on ASSUME_VALID_DTB and further assumes that libfdt
133 * functions are called with valid parameters, i.e. not trigger
134 * FDT_ERR_BADOFFSET or offsets that are out of bounds. It disables any
135 * extensive checking of parameters and the device tree, making various
136 * assumptions about correctness.
137 *
138 * It doesn't make sense to enable this assumption unless
139 * ASSUME_VALID_DTB is also enabled.
140 */
141 ASSUME_VALID_INPUT = 1 << 1,
142
143 /*
144 * This disables checks for device-tree version and removes all code
145 * which handles older versions.
146 *
147 * Only enable this if you know you have a device tree with the latest
148 * version.
149 */
150 ASSUME_LATEST = 1 << 2,
151
152 /*
153 * This assumes that it is OK for a failed addition to the device tree,
154 * due to lack of space or some other problem, to skip any rollback
155 * steps (such as dropping the property name from the string table).
156 * This is safe to enable in most circumstances, even though it may
157 * leave the tree in a sub-optimal state.
158 */
159 ASSUME_NO_ROLLBACK = 1 << 3,
160
161 /*
162 * This assumes that the device tree components appear in a 'convenient'
163 * order, i.e. the memory reservation block first, then the structure
164 * block and finally the string block.
165 *
166 * This order is not specified by the device-tree specification,
167 * but is expected by libfdt. The device-tree compiler always created
168 * device trees with this order.
169 *
170 * This assumption disables a check in fdt_open_into() and removes the
171 * ability to fix the problem there. This is safe if you know that the
172 * device tree is correctly ordered. See fdt_blocks_misordered_().
173 */
174 ASSUME_LIBFDT_ORDER = 1 << 4,
175
176 /*
177 * This assumes that libfdt itself does not have any internal bugs. It
178 * drops certain checks that should never be needed unless libfdt has an
179 * undiscovered bug.
180 *
181 * This can generally be considered safe to enable.
182 */
183 ASSUME_LIBFDT_FLAWLESS = 1 << 5,
184};
185
186/**
187 * can_assume_() - check if a particular assumption is enabled
188 *
189 * @mask: Mask to check (ASSUME_...)
190 * @return true if that assumption is enabled, else false
191 */
192static inline bool can_assume_(int mask)
193{
194 return FDT_ASSUME_MASK & mask;
195}
196
197/** helper macros for checking assumptions */
198#define can_assume(_assume) can_assume_(ASSUME_ ## _assume)
199
200#endif /* LIBFDT_INTERNAL_H */