1 /* SPDX-License-Identifier: GPL-2.0+ */ 2 /* 3 * include/linker_lists.h 4 * 5 * Implementation of linker-generated arrays 6 * 7 * Copyright (C) 2012 Marek Vasut <marex@denx.de> 8 */ 9 10 #ifndef __LINKER_LISTS_H__ 11 #define __LINKER_LISTS_H__ 12 13 #include <linux/compiler.h> 14 15 /* 16 * There is no use in including this from ASM files. 17 * So just don't define anything when included from ASM. 18 */ 19 20 #if !defined(__ASSEMBLY__) 21 22 /** 23 * llsym() - Access a linker-generated array entry 24 * @_type: Data type of the entry 25 * @_name: Name of the entry 26 * @_list: name of the list. Should contain only characters allowed 27 * in a C variable name! 28 */ 29 #define llsym(_type, _name, _list) \ 30 ((_type *)&_u_boot_list_2_##_list##_2_##_name) 31 32 /** 33 * ll_entry_declare() - Declare linker-generated array entry 34 * @_type: Data type of the entry 35 * @_name: Name of the entry 36 * @_list: name of the list. Should contain only characters allowed 37 * in a C variable name! 38 * 39 * This macro declares a variable that is placed into a linker-generated 40 * array. This is a basic building block for more advanced use of linker- 41 * generated arrays. The user is expected to build their own macro wrapper 42 * around this one. 43 * 44 * A variable declared using this macro must be compile-time initialized. 45 * 46 * Special precaution must be made when using this macro: 47 * 48 * 1) The _type must not contain the "static" keyword, otherwise the 49 * entry is generated and can be iterated but is listed in the map 50 * file and cannot be retrieved by name. 51 * 52 * 2) In case a section is declared that contains some array elements AND 53 * a subsection of this section is declared and contains some elements, 54 * it is imperative that the elements are of the same type. 55 * 56 * 3) In case an outer section is declared that contains some array elements 57 * AND an inner subsection of this section is declared and contains some 58 * elements, then when traversing the outer section, even the elements of 59 * the inner sections are present in the array. 60 * 61 * Example: 62 * 63 * :: 64 * 65 * ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub) = { 66 * .x = 3, 67 * .y = 4, 68 * }; 69 */ 70 #define ll_entry_declare(_type, _name, _list) \ 71 _type _u_boot_list_2_##_list##_2_##_name __aligned(4) \ 72 __attribute__((unused, \ 73 section(".u_boot_list_2_"#_list"_2_"#_name))) 74 75 /** 76 * ll_entry_declare_list() - Declare a list of link-generated array entries 77 * @_type: Data type of each entry 78 * @_name: Name of the entry 79 * @_list: name of the list. Should contain only characters allowed 80 * in a C variable name! 81 * 82 * This is like ll_entry_declare() but creates multiple entries. It should 83 * be assigned to an array. 84 * 85 * :: 86 * 87 * ll_entry_declare_list(struct my_sub_cmd, my_sub_cmd, cmd_sub) = { 88 * { .x = 3, .y = 4 }, 89 * { .x = 8, .y = 2 }, 90 * { .x = 1, .y = 7 } 91 * }; 92 */ 93 #define ll_entry_declare_list(_type, _name, _list) \ 94 _type _u_boot_list_2_##_list##_2_##_name[] __aligned(4) \ 95 __attribute__((unused, \ 96 section(".u_boot_list_2_"#_list"_2_"#_name))) 97 98 /* 99 * We need a 0-byte-size type for iterator symbols, and the compiler 100 * does not allow defining objects of C type 'void'. Using an empty 101 * struct is allowed by the compiler, but causes gcc versions 4.4 and 102 * below to complain about aliasing. Therefore we use the next best 103 * thing: zero-sized arrays, which are both 0-byte-size and exempt from 104 * aliasing warnings. 105 */ 106 107 /** 108 * ll_entry_start() - Point to first entry of linker-generated array 109 * @_type: Data type of the entry 110 * @_list: Name of the list in which this entry is placed 111 * 112 * This function returns ``(_type *)`` pointer to the very first entry of a 113 * linker-generated array placed into subsection of .u_boot_list section 114 * specified by _list argument. 115 * 116 * Since this macro defines an array start symbol, its leftmost index 117 * must be 2 and its rightmost index must be 1. 118 * 119 * Example: 120 * 121 * :: 122 * 123 * struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub); 124 */ 125 #define ll_entry_start(_type, _list) \ 126 ({ \ 127 static char start[0] __aligned(CONFIG_LINKER_LIST_ALIGN) \ 128 __attribute__((unused, \ 129 section(".u_boot_list_2_"#_list"_1"))); \ 130 (_type *)&start; \ 131 }) 132 133 /** 134 * ll_entry_end() - Point after last entry of linker-generated array 135 * @_type: Data type of the entry 136 * @_list: Name of the list in which this entry is placed 137 * (with underscores instead of dots) 138 * 139 * This function returns ``(_type *)`` pointer after the very last entry of 140 * a linker-generated array placed into subsection of .u_boot_list 141 * section specified by _list argument. 142 * 143 * Since this macro defines an array end symbol, its leftmost index 144 * must be 2 and its rightmost index must be 3. 145 * 146 * Example: 147 * 148 * :: 149 * 150 * struct my_sub_cmd *msc = ll_entry_end(struct my_sub_cmd, cmd_sub); 151 */ 152 #define ll_entry_end(_type, _list) \ 153 ({ \ 154 static char end[0] __aligned(4) __attribute__((unused, \ 155 section(".u_boot_list_2_"#_list"_3"))); \ 156 (_type *)&end; \ 157 }) 158 /** 159 * ll_entry_count() - Return the number of elements in linker-generated array 160 * @_type: Data type of the entry 161 * @_list: Name of the list of which the number of elements is computed 162 * 163 * This function returns the number of elements of a linker-generated array 164 * placed into subsection of .u_boot_list section specified by _list 165 * argument. The result is of an unsigned int type. 166 * 167 * Example: 168 * 169 * :: 170 * 171 * int i; 172 * const unsigned int count = ll_entry_count(struct my_sub_cmd, cmd_sub); 173 * struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub); 174 * for (i = 0; i < count; i++, msc++) 175 * printf("Entry %i, x=%i y=%i\n", i, msc->x, msc->y); 176 */ 177 #define ll_entry_count(_type, _list) \ 178 ({ \ 179 _type *start = ll_entry_start(_type, _list); \ 180 _type *end = ll_entry_end(_type, _list); \ 181 unsigned int _ll_result = end - start; \ 182 _ll_result; \ 183 }) 184 185 /** 186 * ll_entry_get() - Retrieve entry from linker-generated array by name 187 * @_type: Data type of the entry 188 * @_name: Name of the entry 189 * @_list: Name of the list in which this entry is placed 190 * 191 * This function returns a pointer to a particular entry in linker-generated 192 * array identified by the subsection of u_boot_list where the entry resides 193 * and it's name. 194 * 195 * Example: 196 * 197 * :: 198 * 199 * ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub) = { 200 * .x = 3, 201 * .y = 4, 202 * }; 203 * ... 204 * struct my_sub_cmd *c = ll_entry_get(struct my_sub_cmd, my_sub_cmd, cmd_sub); 205 */ 206 #define ll_entry_get(_type, _name, _list) \ 207 ({ \ 208 extern _type _u_boot_list_2_##_list##_2_##_name; \ 209 _type *_ll_result = \ 210 &_u_boot_list_2_##_list##_2_##_name; \ 211 _ll_result; \ 212 }) 213 214 /** 215 * ll_start() - Point to first entry of first linker-generated array 216 * @_type: Data type of the entry 217 * 218 * This function returns ``(_type *)`` pointer to the very first entry of 219 * the very first linker-generated array. 220 * 221 * Since this macro defines the start of the linker-generated arrays, 222 * its leftmost index must be 1. 223 * 224 * Example: 225 * 226 * :: 227 * 228 * struct my_sub_cmd *msc = ll_start(struct my_sub_cmd); 229 */ 230 #define ll_start(_type) \ 231 ({ \ 232 static char start[0] __aligned(4) __attribute__((unused, \ 233 section(".u_boot_list_1"))); \ 234 (_type *)&start; \ 235 }) 236 237 /** 238 * ll_end() - Point after last entry of last linker-generated array 239 * @_type: Data type of the entry 240 * 241 * This function returns ``(_type *)`` pointer after the very last entry of 242 * the very last linker-generated array. 243 * 244 * Since this macro defines the end of the linker-generated arrays, 245 * its leftmost index must be 3. 246 * 247 * Example: 248 * 249 * :: 250 * 251 * struct my_sub_cmd *msc = ll_end(struct my_sub_cmd); 252 */ 253 #define ll_end(_type) \ 254 ({ \ 255 static char end[0] __aligned(4) __attribute__((unused, \ 256 section(".u_boot_list_3"))); \ 257 (_type *)&end; \ 258 }) 259 260 #endif /* __ASSEMBLY__ */ 261 262 #endif /* __LINKER_LISTS_H__ */ 263