/* SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause) */ #ifndef LIBFDT_INTERNAL_H #define LIBFDT_INTERNAL_H /* * libfdt - Flat Device Tree manipulation * Copyright (C) 2006 David Gibson, IBM Corporation. */ #include <fdt.h> #define FDT_ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1)) #define FDT_TAGALIGN(x) (FDT_ALIGN((x), FDT_TAGSIZE)) int32_t fdt_ro_probe_(const void *fdt); #define FDT_RO_PROBE(fdt) \ { \ if (!can_assume(VALID_DTB)) { \ int32_t totalsize_; \ if ((totalsize_ = fdt_ro_probe_(fdt)) < 0) \ return totalsize_; \ } \ } int fdt_check_node_offset_(const void *fdt, int offset); int fdt_check_prop_offset_(const void *fdt, int offset); const char *fdt_find_string_len_(const char *strtab, int tabsize, const char *s, int s_len); static inline const char *fdt_find_string_(const char *strtab, int tabsize, const char *s) { return fdt_find_string_len_(strtab, tabsize, s, strlen(s)); } int fdt_node_end_offset_(void *fdt, int nodeoffset); static inline const void *fdt_offset_ptr_(const void *fdt, int offset) { return (const char *)fdt + fdt_off_dt_struct(fdt) + offset; } static inline void *fdt_offset_ptr_w_(void *fdt, int offset) { return (void *)(uintptr_t)fdt_offset_ptr_(fdt, offset); } static inline const struct fdt_reserve_entry *fdt_mem_rsv_(const void *fdt, int n) { const struct fdt_reserve_entry *rsv_table = (const struct fdt_reserve_entry *) ((const char *)fdt + fdt_off_mem_rsvmap(fdt)); return rsv_table + n; } static inline struct fdt_reserve_entry *fdt_mem_rsv_w_(void *fdt, int n) { return (void *)(uintptr_t)fdt_mem_rsv_(fdt, n); } /* * Internal helpers to access structural elements of the device tree * blob (rather than for example reading integers from within property * values). We assume that we are either given a naturally aligned * address for the platform or if we are not, we are on a platform * where unaligned memory reads will be handled in a graceful manner. * If not the external helpers fdtXX_ld() from libfdt.h can be used * instead. */ static inline uint32_t fdt32_ld_(const fdt32_t *p) { return fdt32_to_cpu(*p); } static inline uint64_t fdt64_ld_(const fdt64_t *p) { return fdt64_to_cpu(*p); } #define FDT_SW_MAGIC (~FDT_MAGIC) /**********************************************************************/ /* Checking controls */ /**********************************************************************/ #ifndef FDT_ASSUME_MASK #define FDT_ASSUME_MASK 0 #endif /* * Defines assumptions which can be enabled. Each of these can be enabled * individually. For maximum safety, don't enable any assumptions! * * For minimal code size and no safety, use ASSUME_PERFECT at your own risk. * You should have another method of validating the device tree, such as a * signature or hash check before using libfdt. * * For situations where security is not a concern it may be safe to enable * ASSUME_PERFECT. */ enum { /* * This does essentially no checks. Only the latest device-tree * version is correctly handled. Inconsistencies or errors in the device * tree may cause undefined behaviour or crashes. Invalid parameters * passed to libfdt may do the same. * * If an error occurs when modifying the tree it may leave the tree in * an intermediate (but valid) state. As an example, adding a property * where there is insufficient space may result in the property name * being added to the string table even though the property itself is * not added to the struct section. * * Only use this if you have a fully validated device tree with * the latest supported version and wish to minimise code size. */ ASSUME_PERFECT = 0xff, /* * This assumes that the device tree is sane. i.e. header metadata * and basic hierarchy are correct. * * With this assumption enabled, normal device trees produced by libfdt * and the compiler should be handled safely. Malicious device trees and * complete garbage may cause libfdt to behave badly or crash. Truncated * device trees (e.g. those only partially loaded) can also cause * problems. * * Note: Only checks that relate exclusively to the device tree itself * (not the parameters passed to libfdt) are disabled by this * assumption. This includes checking headers, tags and the like. */ ASSUME_VALID_DTB = 1 << 0, /* * This builds on ASSUME_VALID_DTB and further assumes that libfdt * functions are called with valid parameters, i.e. not trigger * FDT_ERR_BADOFFSET or offsets that are out of bounds. It disables any * extensive checking of parameters and the device tree, making various * assumptions about correctness. * * It doesn't make sense to enable this assumption unless * ASSUME_VALID_DTB is also enabled. */ ASSUME_VALID_INPUT = 1 << 1, /* * This disables checks for device-tree version and removes all code * which handles older versions. * * Only enable this if you know you have a device tree with the latest * version. */ ASSUME_LATEST = 1 << 2, /* * This assumes that it is OK for a failed addition to the device tree, * due to lack of space or some other problem, to skip any rollback * steps (such as dropping the property name from the string table). * This is safe to enable in most circumstances, even though it may * leave the tree in a sub-optimal state. */ ASSUME_NO_ROLLBACK = 1 << 3, /* * This assumes that the device tree components appear in a 'convenient' * order, i.e. the memory reservation block first, then the structure * block and finally the string block. * * This order is not specified by the device-tree specification, * but is expected by libfdt. The device-tree compiler always created * device trees with this order. * * This assumption disables a check in fdt_open_into() and removes the * ability to fix the problem there. This is safe if you know that the * device tree is correctly ordered. See fdt_blocks_misordered_(). */ ASSUME_LIBFDT_ORDER = 1 << 4, /* * This assumes that libfdt itself does not have any internal bugs. It * drops certain checks that should never be needed unless libfdt has an * undiscovered bug. * * This can generally be considered safe to enable. */ ASSUME_LIBFDT_FLAWLESS = 1 << 5, }; /** * can_assume_() - check if a particular assumption is enabled * * @mask: Mask to check (ASSUME_...) * @return true if that assumption is enabled, else false */ static inline bool can_assume_(int mask) { return FDT_ASSUME_MASK & mask; } /** helper macros for checking assumptions */ #define can_assume(_assume) can_assume_(ASSUME_ ## _assume) #endif /* LIBFDT_INTERNAL_H */
