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 * tmp = (_type *)&start; \ 131 asm("":"+r"(tmp)); \ 132 tmp; \ 133}) 134 135/** 136 * ll_entry_end() - Point after last entry of linker-generated array 137 * @_type: Data type of the entry 138 * @_list: Name of the list in which this entry is placed 139 * (with underscores instead of dots) 140 * 141 * This function returns ``(_type *)`` pointer after the very last entry of 142 * a linker-generated array placed into subsection of __u_boot_list 143 * section specified by _list argument. 144 * 145 * Since this macro defines an array end symbol, its leftmost index 146 * must be 2 and its rightmost index must be 3. 147 * 148 * Example: 149 * 150 * :: 151 * 152 * struct my_sub_cmd *msc = ll_entry_end(struct my_sub_cmd, cmd_sub); 153 */ 154#define ll_entry_end(_type, _list) \ 155({ \ 156 static char end[0] __aligned(4) __attribute__((unused)) \ 157 __section("__u_boot_list_2_"#_list"_3"); \ 158 _type * tmp = (_type *)&end; \ 159 asm("":"+r"(tmp)); \ 160 tmp; \ 161}) 162/** 163 * ll_entry_count() - Return the number of elements in linker-generated array 164 * @_type: Data type of the entry 165 * @_list: Name of the list of which the number of elements is computed 166 * 167 * This function returns the number of elements of a linker-generated array 168 * placed into subsection of __u_boot_list section specified by _list 169 * argument. The result is of an unsigned int type. 170 * 171 * Example: 172 * 173 * :: 174 * 175 * int i; 176 * const unsigned int count = ll_entry_count(struct my_sub_cmd, cmd_sub); 177 * struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub); 178 * for (i = 0; i < count; i++, msc++) 179 * printf("Entry %i, x=%i y=%i\n", i, msc->x, msc->y); 180 */ 181#define ll_entry_count(_type, _list) \ 182 ({ \ 183 _type *start = ll_entry_start(_type, _list); \ 184 _type *end = ll_entry_end(_type, _list); \ 185 unsigned int _ll_result = end - start; \ 186 _ll_result; \ 187 }) 188 189/** 190 * ll_entry_get() - Retrieve entry from linker-generated array by name 191 * @_type: Data type of the entry 192 * @_name: Name of the entry 193 * @_list: Name of the list in which this entry is placed 194 * 195 * This function returns a pointer to a particular entry in linker-generated 196 * array identified by the subsection of u_boot_list where the entry resides 197 * and it's name. 198 * 199 * Example: 200 * 201 * :: 202 * 203 * ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub) = { 204 * .x = 3, 205 * .y = 4, 206 * }; 207 * ... 208 * struct my_sub_cmd *c = ll_entry_get(struct my_sub_cmd, my_sub_cmd, cmd_sub); 209 */ 210#define ll_entry_get(_type, _name, _list) \ 211 ({ \ 212 extern _type _u_boot_list_2_##_list##_2_##_name; \ 213 _type *_ll_result = \ 214 &_u_boot_list_2_##_list##_2_##_name; \ 215 _ll_result; \ 216 }) 217 218/** 219 * ll_entry_ref() - Get a reference to a linker-generated array entry 220 * 221 * Once an extern ll_entry_declare() has been used to declare the reference, 222 * this macro allows the entry to be accessed. 223 * 224 * This is like ll_entry_get(), but without the extra code, so it is suitable 225 * for putting into data structures. 226 * 227 * @_type: C type of the list entry, e.g. 'struct foo' 228 * @_name: name of the entry 229 * @_list: name of the list 230 */ 231#define ll_entry_ref(_type, _name, _list) \ 232 ((_type *)&_u_boot_list_2_##_list##_2_##_name) 233 234/** 235 * ll_start() - Point to first entry of first linker-generated array 236 * @_type: Data type of the entry 237 * 238 * This function returns ``(_type *)`` pointer to the very first entry of 239 * the very first linker-generated array. 240 * 241 * Since this macro defines the start of the linker-generated arrays, 242 * its leftmost index must be 1. 243 * 244 * Example: 245 * 246 * :: 247 * 248 * struct my_sub_cmd *msc = ll_start(struct my_sub_cmd); 249 */ 250#define ll_start(_type) \ 251({ \ 252 static char start[0] __aligned(4) __attribute__((unused)) \ 253 __section("__u_boot_list_1"); \ 254 _type * tmp = (_type *)&start; \ 255 asm("":"+r"(tmp)); \ 256 tmp; \ 257}) 258 259/** 260 * ll_end() - Point after last entry of last linker-generated array 261 * @_type: Data type of the entry 262 * 263 * This function returns ``(_type *)`` pointer after the very last entry of 264 * the very last linker-generated array. 265 * 266 * Since this macro defines the end of the linker-generated arrays, 267 * its leftmost index must be 3. 268 * 269 * Example: 270 * 271 * :: 272 * 273 * struct my_sub_cmd *msc = ll_end(struct my_sub_cmd); 274 */ 275#define ll_end(_type) \ 276({ \ 277 static char end[0] __aligned(4) __attribute__((unused)) \ 278 __section("__u_boot_list_3"); \ 279 _type * tmp = (_type *)&end; \ 280 asm("":"+r"(tmp)); \ 281 tmp; \ 282}) 283 284#endif /* __ASSEMBLY__ */ 285 286#endif /* __LINKER_LISTS_H__ */ 287