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/* SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause) */
* 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))
int32_t fdt_ro_probe_(const void *fdt);
#define FDT_RO_PROBE(fdt) \
{ \
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_(const char *strtab, int tabsize, const char *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 tructural elements of the device tree
* blob (rather than for exaple 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);
/* Checking controls */
* 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
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.
* 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.
* 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.
* 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.
* 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.
* 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_().
* 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.
* 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 */