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 int fdt_ro_probe_(const void *fdt);
14 #define FDT_RO_PROBE(fdt) \
15 { \
16 int totalsize_; \
17 if (fdt_chk_basic()) { \
18 totalsize_ = fdt_ro_probe_(fdt); \
19 if (totalsize_ < 0) \
20 return totalsize_; \
21 } \
22 }
23
24 int fdt_check_node_offset_(const void *fdt, int offset);
25 int fdt_check_prop_offset_(const void *fdt, int offset);
26 const char *fdt_find_string_(const char *strtab, int tabsize, const char *s);
27 int fdt_node_end_offset_(void *fdt, int nodeoffset);
28
fdt_offset_ptr_(const void * fdt,int offset)29 static inline const void *fdt_offset_ptr_(const void *fdt, int offset)
30 {
31 return (const char *)fdt + fdt_off_dt_struct(fdt) + offset;
32 }
33
fdt_offset_ptr_w_(void * fdt,int offset)34 static inline void *fdt_offset_ptr_w_(void *fdt, int offset)
35 {
36 return (void *)(uintptr_t)fdt_offset_ptr_(fdt, offset);
37 }
38
fdt_mem_rsv_(const void * fdt,int n)39 static inline const struct fdt_reserve_entry *fdt_mem_rsv_(const void *fdt, int n)
40 {
41 const struct fdt_reserve_entry *rsv_table =
42 (const struct fdt_reserve_entry *)
43 ((const char *)fdt + fdt_off_mem_rsvmap(fdt));
44
45 return rsv_table + n;
46 }
fdt_mem_rsv_w_(void * fdt,int n)47 static inline struct fdt_reserve_entry *fdt_mem_rsv_w_(void *fdt, int n)
48 {
49 return (void *)(uintptr_t)fdt_mem_rsv_(fdt, n);
50 }
51
52 #define FDT_SW_MAGIC (~FDT_MAGIC)
53
54 /**********************************************************************/
55 /* Checking controls */
56 /**********************************************************************/
57
58 #ifndef FDT_ASSUME_MASK
59 #define FDT_ASSUME_MASK 0
60 #endif
61
62 /*
63 * Defines assumptions which can be enabled. Each of these can be enabled
64 * individually. For maximum saftey, don't enable any assumptions!
65 *
66 * For minimal code size and no safety, use FDT_ASSUME_PERFECT at your own risk.
67 * You should have another method of validating the device tree, such as a
68 * signature or hash check before using libfdt.
69 *
70 * For situations where security is not a concern it may be safe to enable
71 * FDT_ASSUME_FRIENDLY.
72 */
73 enum {
74 /*
75 * This does essentially no checks. Only the latest device-tree
76 * version is correctly handled. Incosistencies or errors in the device
77 * tree may cause undefined behaviour or crashes.
78 *
79 * If an error occurs when modifying the tree it may leave the tree in
80 * an intermediate (but valid) state. As an example, adding a property
81 * where there is insufficient space may result in the property name
82 * being added to the string table even though the property itself is
83 * not added to the struct section.
84 *
85 * Only use this if you have a fully validated device tree with
86 * the latest supported version and wish to minimise code size.
87 */
88 FDT_ASSUME_PERFECT = 0xff,
89
90 /*
91 * This assumes that the device tree is sane. i.e. header metadata
92 * and basic hierarchy are correct.
93 *
94 * These checks will be sufficient if you have a valid device tree with
95 * no internal inconsistencies. With this assumption, libfdt will
96 * generally not return -FDT_ERR_INTERNAL, -FDT_ERR_BADLAYOUT, etc.
97 */
98 FDT_ASSUME_SANE = 1 << 0,
99
100 /*
101 * This disables checks for device-tree version and removes all code
102 * which handles older versions.
103 *
104 * Only enable this if you know you have a device tree with the latest
105 * version.
106 */
107 FDT_ASSUME_LATEST = 1 << 1,
108
109 /*
110 * This disables any extensive checking of parameters and the device
111 * tree, making various assumptions about correctness. Normal device
112 * trees produced by libfdt and the compiler should be handled safely.
113 * Malicious device trees and complete garbage may cause libfdt to
114 * behave badly or crash.
115 */
116 FDT_ASSUME_FRIENDLY = 1 << 2,
117 };
118
119 /** fdt_chk_basic() - see if basic checking of params and DT data is enabled */
fdt_chk_basic(void)120 static inline bool fdt_chk_basic(void)
121 {
122 return !(FDT_ASSUME_MASK & FDT_ASSUME_SANE);
123 }
124
125 /** fdt_chk_version() - see if we need to handle old versions of the DT */
fdt_chk_version(void)126 static inline bool fdt_chk_version(void)
127 {
128 return !(FDT_ASSUME_MASK & FDT_ASSUME_LATEST);
129 }
130
131 /** fdt_chk_extra() - see if extra checking is enabled */
fdt_chk_extra(void)132 static inline bool fdt_chk_extra(void)
133 {
134 return !(FDT_ASSUME_MASK & FDT_ASSUME_FRIENDLY);
135 }
136
137 #endif /* LIBFDT_INTERNAL_H */
138