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