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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 if (!can_assume(VALID_DTB)) { \
17 int32_t totalsize_; \
18 if ((totalsize_ = fdt_ro_probe_(fdt)) < 0) \
19 return totalsize_; \
20 } \
21 }
22
23int fdt_check_node_offset_(const void *fdt, int offset);
24int fdt_check_prop_offset_(const void *fdt, int offset);
25
26const char *fdt_find_string_len_(const char *strtab, int tabsize, const char *s,
27 int s_len);
28static 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
34int fdt_node_end_offset_(void *fdt, int nodeoffset);
35
36static 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
41static inline void *fdt_offset_ptr_w_(void *fdt, int offset)
42{
43 return (void *)(uintptr_t)fdt_offset_ptr_(fdt, offset);
44}
45
46static 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}
54static 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 */
68static inline uint32_t fdt32_ld_(const fdt32_t *p)
69{
70 return fdt32_to_cpu(*p);
71}
72
73static 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 */
99enum {
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 */
194static 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 */