include/binman_sym.h

   1 /* SPDX-License-Identifier: GPL-2.0+ */
   2 /*
   3  * Symbol access for symbols set up by binman as part of the build.
   4  *
   5  * This allows C code to access the position of a particular part of the image
   6  * assembled by binman.
   7  *
   8  * Copyright (c) 2017 Google, Inc
   9  */
  10
  11 #ifndef __BINMAN_SYM_H
  12 #define __BINMAN_SYM_H
  13
  14 /* BSYM in little endian, keep in sync with tools/binman/elf.py */
  15 #define BINMAN_SYM_MAGIC_VALUE  (0x4d595342UL)
  16 #define BINMAN_SYM_MISSING      (-1UL)
  17
  18 #if CONFIG_IS_ENABLED(BINMAN_SYMBOLS)
  19
  20 /**
  21  * binman_symname() - Internal function to get a binman symbol name
  22  *
  23  * @entry_name: Name of the entry to look for (e.g. 'u_boot_spl')
  24  * @_prop_name: Property value to get from that entry (e.g. 'pos')
  25  * @returns name of the symbol for that entry and property
  26  */
  27 #define binman_symname(_entry_name, _prop_name) \
  28         _binman_ ## _entry_name ## _prop_ ## _prop_name
  29
  30 /**
  31  * binman_sym_declare() - Declare a symbol that will be used at run-time
  32  *
  33  * @_type: Type f the symbol (e.g. unsigned long)
  34  * @entry_name: Name of the entry to look for (e.g. 'u_boot_spl')
  35  * @_prop_name: Property value to get from that entry (e.g. 'pos')
  36  */
  37 #define binman_sym_declare(_type, _entry_name, _prop_name) \
  38         _type binman_symname(_entry_name, _prop_name) \
  39                 __attribute__((aligned(4), unused, section(".binman_sym")))
  40
  41 /**
  42  * binman_sym_extern() - Declare a extern symbol that will be used at run-time
  43  *
  44  * @_type: Type f the symbol (e.g. unsigned long)
  45  * @entry_name: Name of the entry to look for (e.g. 'u_boot_spl')
  46  * @_prop_name: Property value to get from that entry (e.g. 'pos')
  47  */
  48 #define binman_sym_extern(_type, _entry_name, _prop_name) \
  49         extern _type binman_symname(_entry_name, _prop_name) \
  50                 __attribute__((aligned(4), unused, section(".binman_sym")))
  51
  52 /**
  53  * binman_sym_declare_optional() - Declare an optional symbol
  54  *
  55  * If this symbol cannot be provided by binman, an error will not be generated.
  56  * Instead the image will be assigned the value BINMAN_SYM_MISSING.
  57  *
  58  * @_type: Type f the symbol (e.g. unsigned long)
  59  * @entry_name: Name of the entry to look for (e.g. 'u_boot_spl')
  60  * @_prop_name: Property value to get from that entry (e.g. 'pos')
  61  */
  62 #define binman_sym_declare_optional(_type, _entry_name, _prop_name) \
  63         _type binman_symname(_entry_name, _prop_name) \
  64                 __attribute__((aligned(4), weak, unused, \
  65                 section(".binman_sym")))
  66
  67 /**
  68  * _binman_sym_magic - Internal magic symbol for validity checks
  69  *
  70  * When building images, binman fills in this symbol with the magic
  71  * value #defined above. This is used to check at runtime if the
  72  * symbol values were filled in and are OK to use.
  73  */
  74 extern unsigned long _binman_sym_magic;
  75
  76 /**
  77  * DECLARE_BINMAN_MAGIC_SYM - Declare the internal magic symbol
  78  *
  79  * This macro declares the _binman_sym_magic symbol so that it exists.
  80  * Declaring it here would cause errors during linking due to multiple
  81  * definitions of the symbol.
  82  */
  83 #define DECLARE_BINMAN_MAGIC_SYM \
  84         unsigned long _binman_sym_magic \
  85                 __attribute__((aligned(4), section(".binman_sym")))
  86
  87 /**
  88  * BINMAN_SYMS_OK - Check if the symbol values are valid
  89  *
  90  * This macro checks if the magic symbol's value is filled properly,
  91  * which indicates that other symbols are OK to use as well.
  92  *
  93  * Return: 1 if binman symbol values are usable, 0 if not
  94  */
  95 #define BINMAN_SYMS_OK \
  96         (*(unsigned long *)&_binman_sym_magic == BINMAN_SYM_MAGIC_VALUE)
  97
  98 /**
  99  * binman_sym() - Access a previously declared symbol
 100  *
 101  * This is used to get the value of a symbol. E.g.:
 102  *
 103  *    unsigned long address = binman_sym(unsigned long, u_boot_spl, pos);
 104  *
 105  * @_type: Type f the symbol (e.g. unsigned long)
 106  * @entry_name: Name of the entry to look for (e.g. 'u_boot_spl')
 107  * @_prop_name: Property value to get from that entry (e.g. 'pos')
 108  *
 109  * Return: value of that property (filled in by binman), or
 110  *         BINMAN_SYM_MISSING if the value is unavailable
 111  */
 112 #define binman_sym(_type, _entry_name, _prop_name) \
 113         (BINMAN_SYMS_OK ? \
 114          (*(_type *)&binman_symname(_entry_name, _prop_name)) : \
 115          BINMAN_SYM_MISSING)
 116
 117 #else /* !CONFIG_IS_ENABLED(BINMAN_SYMBOLS) */
 118
 119 #define binman_sym_declare(_type, _entry_name, _prop_name)
 120
 121 #define binman_sym_declare_optional(_type, _entry_name, _prop_name)
 122
 123 #define binman_sym_extern(_type, _entry_name, _prop_name)
 124
 125 #define DECLARE_BINMAN_MAGIC_SYM
 126
 127 #define BINMAN_SYMS_OK (0)
 128
 129 #define binman_sym(_type, _entry_name, _prop_name) BINMAN_SYM_MISSING
 130
 131 #endif /* CONFIG_IS_ENABLED(BINMAN_SYMBOLS) */
 132
 133 #endif