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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                 :            : 
      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                 :            : 
      26                 :       6752 : static inline const void *fdt_offset_ptr_(const void *fdt, int offset)
      27                 :            : {
      28                 :       6752 :         return (const char *)fdt + fdt_off_dt_struct(fdt) + offset;
      29                 :            : }
      30                 :            : 
      31                 :       1853 : static inline void *fdt_offset_ptr_w_(void *fdt, int offset)
      32                 :            : {
      33                 :       1853 :         return (void *)(uintptr_t)fdt_offset_ptr_(fdt, offset);
      34                 :            : }
      35                 :            : 
      36                 :          0 : static inline const struct fdt_reserve_entry *fdt_mem_rsv_(const void *fdt, int n)
      37                 :            : {
      38                 :          0 :         const struct fdt_reserve_entry *rsv_table =
      39                 :            :                 (const struct fdt_reserve_entry *)
      40                 :          0 :                 ((const char *)fdt + fdt_off_mem_rsvmap(fdt));
      41                 :            : 
      42                 :          0 :         return rsv_table + n;
      43                 :            : }
      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                 :            :  */
      58                 :          0 : static inline uint32_t fdt32_ld_(const fdt32_t *p)
      59                 :            : {
      60                 :          0 :         return fdt32_to_cpu(*p);
      61                 :            : }
      62                 :            : 
      63                 :          0 : static inline uint64_t fdt64_ld_(const fdt64_t *p)
      64                 :            : {
      65                 :          0 :         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                 :            :  */
     184                 :      14878 : static inline bool can_assume_(int mask)
     185                 :            : {
     186                 :      14878 :         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 */