1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_INIT_H 3 #define _LINUX_INIT_H 4 5 #include <linux/build_bug.h> 6 #include <linux/compiler.h> 7 #include <linux/stringify.h> 8 #include <linux/types.h> 9 10 /* Built-in __init functions needn't be compiled with retpoline */ 11 #if defined(__noretpoline) && !defined(MODULE) 12 #define __noinitretpoline __noretpoline 13 #else 14 #define __noinitretpoline 15 #endif 16 17 /* These macros are used to mark some functions or 18 * initialized data (doesn't apply to uninitialized data) 19 * as `initialization' functions. The kernel can take this 20 * as hint that the function is used only during the initialization 21 * phase and free up used memory resources after 22 * 23 * Usage: 24 * For functions: 25 * 26 * You should add __init immediately before the function name, like: 27 * 28 * static void __init initme(int x, int y) 29 * { 30 * extern int z; z = x * y; 31 * } 32 * 33 * If the function has a prototype somewhere, you can also add 34 * __init between closing brace of the prototype and semicolon: 35 * 36 * extern int initialize_foobar_device(int, int, int) __init; 37 * 38 * For initialized data: 39 * You should insert __initdata or __initconst between the variable name 40 * and equal sign followed by value, e.g.: 41 * 42 * static int init_variable __initdata = 0; 43 * static const char linux_logo[] __initconst = { 0x32, 0x36, ... }; 44 * 45 * Don't forget to initialize data not at file scope, i.e. within a function, 46 * as gcc otherwise puts the data into the bss section and not into the init 47 * section. 48 */ 49 50 /* These are for everybody (although not all archs will actually 51 discard it in modules) */ 52 #define __init __section(".init.text") __cold __latent_entropy __noinitretpoline 53 #define __initdata __section(".init.data") 54 #define __initconst __section(".init.rodata") 55 #define __exitdata __section(".exit.data") 56 #define __exit_call __used __section(".exitcall.exit") 57 58 /* 59 * modpost check for section mismatches during the kernel build. 60 * A section mismatch happens when there are references from a 61 * code or data section to an init section (both code or data). 62 * The init sections are (for most archs) discarded by the kernel 63 * when early init has completed so all such references are potential bugs. 64 * For exit sections the same issue exists. 65 * 66 * The following markers are used for the cases where the reference to 67 * the *init / *exit section (code or data) is valid and will teach 68 * modpost not to issue a warning. Intended semantics is that a code or 69 * data tagged __ref* can reference code or data from init section without 70 * producing a warning (of course, no warning does not mean code is 71 * correct, so optimally document why the __ref is needed and why it's OK). 72 * 73 * The markers follow same syntax rules as __init / __initdata. 74 */ 75 #define __ref __section(".ref.text") noinline 76 #define __refdata __section(".ref.data") 77 #define __refconst __section(".ref.rodata") 78 79 #ifdef MODULE 80 #define __exitused 81 #else 82 #define __exitused __used 83 #endif 84 85 #define __exit __section(".exit.text") __exitused __cold notrace 86 87 /* Used for MEMORY_HOTPLUG */ 88 #define __meminit __section(".meminit.text") __cold notrace \ 89 __latent_entropy 90 #define __meminitdata __section(".meminit.data") 91 #define __meminitconst __section(".meminit.rodata") 92 #define __memexit __section(".memexit.text") __exitused __cold notrace 93 #define __memexitdata __section(".memexit.data") 94 #define __memexitconst __section(".memexit.rodata") 95 96 /* For assembly routines */ 97 #define __HEAD .section ".head.text","ax" 98 #define __INIT .section ".init.text","ax" 99 #define __FINIT .previous 100 101 #define __INITDATA .section ".init.data","aw",%progbits 102 #define __INITRODATA .section ".init.rodata","a",%progbits 103 #define __FINITDATA .previous 104 105 #define __MEMINIT .section ".meminit.text", "ax" 106 #define __MEMINITDATA .section ".meminit.data", "aw" 107 #define __MEMINITRODATA .section ".meminit.rodata", "a" 108 109 /* silence warnings when references are OK */ 110 #define __REF .section ".ref.text", "ax" 111 #define __REFDATA .section ".ref.data", "aw" 112 #define __REFCONST .section ".ref.rodata", "a" 113 114 #ifndef __ASSEMBLY__ 115 /* 116 * Used for initialization calls.. 117 */ 118 typedef int (*initcall_t)(void); 119 typedef void (*exitcall_t)(void); 120 121 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 122 typedef int initcall_entry_t; 123 124 static inline initcall_t initcall_from_entry(initcall_entry_t *entry) 125 { 126 return offset_to_ptr(entry); 127 } 128 #else 129 typedef initcall_t initcall_entry_t; 130 131 static inline initcall_t initcall_from_entry(initcall_entry_t *entry) 132 { 133 return *entry; 134 } 135 #endif 136 137 extern initcall_entry_t __con_initcall_start[], __con_initcall_end[]; 138 139 /* Used for constructor calls. */ 140 typedef void (*ctor_fn_t)(void); 141 142 struct file_system_type; 143 144 /* Defined in init/main.c */ 145 extern int do_one_initcall(initcall_t fn); 146 extern char __initdata boot_command_line[]; 147 extern char *saved_command_line; 148 extern unsigned int saved_command_line_len; 149 extern unsigned int reset_devices; 150 151 /* used by init/main.c */ 152 void setup_arch(char **); 153 void prepare_namespace(void); 154 void __init init_rootfs(void); 155 extern struct file_system_type rootfs_fs_type; 156 157 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX) 158 extern bool rodata_enabled; 159 #endif 160 #ifdef CONFIG_STRICT_KERNEL_RWX 161 void mark_rodata_ro(void); 162 #endif 163 164 extern void (*late_time_init)(void); 165 166 extern bool initcall_debug; 167 168 #endif 169 170 #ifndef MODULE 171 172 #ifndef __ASSEMBLY__ 173 174 /* 175 * initcalls are now grouped by functionality into separate 176 * subsections. Ordering inside the subsections is determined 177 * by link order. 178 * For backwards compatibility, initcall() puts the call in 179 * the device init subsection. 180 * 181 * The `id' arg to __define_initcall() is needed so that multiple initcalls 182 * can point at the same handler without causing duplicate-symbol build errors. 183 * 184 * Initcalls are run by placing pointers in initcall sections that the 185 * kernel iterates at runtime. The linker can do dead code / data elimination 186 * and remove that completely, so the initcall sections have to be marked 187 * as KEEP() in the linker script. 188 */ 189 190 /* Format: <modname>__<counter>_<line>_<fn> */ 191 #define __initcall_id(fn) \ 192 __PASTE(__KBUILD_MODNAME, \ 193 __PASTE(__, \ 194 __PASTE(__COUNTER__, \ 195 __PASTE(_, \ 196 __PASTE(__LINE__, \ 197 __PASTE(_, fn)))))) 198 199 /* Format: __<prefix>__<iid><id> */ 200 #define __initcall_name(prefix, __iid, id) \ 201 __PASTE(__, \ 202 __PASTE(prefix, \ 203 __PASTE(__, \ 204 __PASTE(__iid, id)))) 205 206 #ifdef CONFIG_LTO_CLANG 207 /* 208 * With LTO, the compiler doesn't necessarily obey link order for 209 * initcalls. In order to preserve the correct order, we add each 210 * variable into its own section and generate a linker script (in 211 * scripts/link-vmlinux.sh) to specify the order of the sections. 212 */ 213 #define __initcall_section(__sec, __iid) \ 214 #__sec ".init.." #__iid 215 216 /* 217 * With LTO, the compiler can rename static functions to avoid 218 * global naming collisions. We use a global stub function for 219 * initcalls to create a stable symbol name whose address can be 220 * taken in inline assembly when PREL32 relocations are used. 221 */ 222 #define __initcall_stub(fn, __iid, id) \ 223 __initcall_name(initstub, __iid, id) 224 225 #define __define_initcall_stub(__stub, fn) \ 226 int __init __stub(void); \ 227 int __init __stub(void) \ 228 { \ 229 return fn(); \ 230 } \ 231 __ADDRESSABLE(__stub) 232 #else 233 #define __initcall_section(__sec, __iid) \ 234 #__sec ".init" 235 236 #define __initcall_stub(fn, __iid, id) fn 237 238 #define __define_initcall_stub(__stub, fn) \ 239 __ADDRESSABLE(fn) 240 #endif 241 242 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 243 #define ____define_initcall(fn, __stub, __name, __sec) \ 244 __define_initcall_stub(__stub, fn) \ 245 asm(".section \"" __sec "\", \"a\" \n" \ 246 __stringify(__name) ": \n" \ 247 ".long " __stringify(__stub) " - . \n" \ 248 ".previous \n"); \ 249 static_assert(__same_type(initcall_t, &fn)); 250 #else 251 #define ____define_initcall(fn, __unused, __name, __sec) \ 252 static initcall_t __name __used \ 253 __attribute__((__section__(__sec))) = fn; 254 #endif 255 256 #define __unique_initcall(fn, id, __sec, __iid) \ 257 ____define_initcall(fn, \ 258 __initcall_stub(fn, __iid, id), \ 259 __initcall_name(initcall, __iid, id), \ 260 __initcall_section(__sec, __iid)) 261 262 #define ___define_initcall(fn, id, __sec) \ 263 __unique_initcall(fn, id, __sec, __initcall_id(fn)) 264 265 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id) 266 267 /* 268 * Early initcalls run before initializing SMP. 269 * 270 * Only for built-in code, not modules. 271 */ 272 #define early_initcall(fn) __define_initcall(fn, early) 273 274 /* 275 * A "pure" initcall has no dependencies on anything else, and purely 276 * initializes variables that couldn't be statically initialized. 277 * 278 * This only exists for built-in code, not for modules. 279 * Keep main.c:initcall_level_names[] in sync. 280 */ 281 #define pure_initcall(fn) __define_initcall(fn, 0) 282 283 #define core_initcall(fn) __define_initcall(fn, 1) 284 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 285 #define postcore_initcall(fn) __define_initcall(fn, 2) 286 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 287 #define arch_initcall(fn) __define_initcall(fn, 3) 288 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 289 #define subsys_initcall(fn) __define_initcall(fn, 4) 290 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 291 #define fs_initcall(fn) __define_initcall(fn, 5) 292 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 293 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 294 #define device_initcall(fn) __define_initcall(fn, 6) 295 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 296 #define late_initcall(fn) __define_initcall(fn, 7) 297 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 298 299 #define __initcall(fn) device_initcall(fn) 300 301 #define __exitcall(fn) \ 302 static exitcall_t __exitcall_##fn __exit_call = fn 303 304 #define console_initcall(fn) ___define_initcall(fn, con, .con_initcall) 305 306 struct obs_kernel_param { 307 const char *str; 308 int (*setup_func)(char *); 309 int early; 310 }; 311 312 /* 313 * Only for really core code. See moduleparam.h for the normal way. 314 * 315 * Force the alignment so the compiler doesn't space elements of the 316 * obs_kernel_param "array" too far apart in .init.setup. 317 */ 318 #define __setup_param(str, unique_id, fn, early) \ 319 static const char __setup_str_##unique_id[] __initconst \ 320 __aligned(1) = str; \ 321 static struct obs_kernel_param __setup_##unique_id \ 322 __used __section(".init.setup") \ 323 __aligned(__alignof__(struct obs_kernel_param)) \ 324 = { __setup_str_##unique_id, fn, early } 325 326 /* 327 * NOTE: __setup functions return values: 328 * @fn returns 1 (or non-zero) if the option argument is "handled" 329 * and returns 0 if the option argument is "not handled". 330 */ 331 #define __setup(str, fn) \ 332 __setup_param(str, fn, fn, 0) 333 334 /* 335 * NOTE: @fn is as per module_param, not __setup! 336 * I.e., @fn returns 0 for no error or non-zero for error 337 * (possibly @fn returns a -errno value, but it does not matter). 338 * Emits warning if @fn returns non-zero. 339 */ 340 #define early_param(str, fn) \ 341 __setup_param(str, fn, fn, 1) 342 343 #define early_param_on_off(str_on, str_off, var, config) \ 344 \ 345 int var = IS_ENABLED(config); \ 346 \ 347 static int __init parse_##var##_on(char *arg) \ 348 { \ 349 var = 1; \ 350 return 0; \ 351 } \ 352 early_param(str_on, parse_##var##_on); \ 353 \ 354 static int __init parse_##var##_off(char *arg) \ 355 { \ 356 var = 0; \ 357 return 0; \ 358 } \ 359 early_param(str_off, parse_##var##_off) 360 361 /* Relies on boot_command_line being set */ 362 void __init parse_early_param(void); 363 void __init parse_early_options(char *cmdline); 364 #endif /* __ASSEMBLY__ */ 365 366 #else /* MODULE */ 367 368 #define __setup_param(str, unique_id, fn) /* nothing */ 369 #define __setup(str, func) /* nothing */ 370 #endif 371 372 /* Data marked not to be saved by software suspend */ 373 #define __nosavedata __section(".data..nosave") 374 375 #ifdef MODULE 376 #define __exit_p(x) x 377 #else 378 #define __exit_p(x) NULL 379 #endif 380 381 #endif /* _LINUX_INIT_H */ 382