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 93 /* For assembly routines */ 94 #define __HEAD .section ".head.text","ax" 95 #define __INIT .section ".init.text","ax" 96 #define __FINIT .previous 97 98 #define __INITDATA .section ".init.data","aw",%progbits 99 #define __INITRODATA .section ".init.rodata","a",%progbits 100 #define __FINITDATA .previous 101 102 /* silence warnings when references are OK */ 103 #define __REF .section ".ref.text", "ax" 104 #define __REFDATA .section ".ref.data", "aw" 105 #define __REFCONST .section ".ref.rodata", "a" 106 107 #ifndef __ASSEMBLY__ 108 /* 109 * Used for initialization calls.. 110 */ 111 typedef int (*initcall_t)(void); 112 typedef void (*exitcall_t)(void); 113 114 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 115 typedef int initcall_entry_t; 116 117 static inline initcall_t initcall_from_entry(initcall_entry_t *entry) 118 { 119 return offset_to_ptr(entry); 120 } 121 #else 122 typedef initcall_t initcall_entry_t; 123 124 static inline initcall_t initcall_from_entry(initcall_entry_t *entry) 125 { 126 return *entry; 127 } 128 #endif 129 130 extern initcall_entry_t __con_initcall_start[], __con_initcall_end[]; 131 132 /* Used for constructor calls. */ 133 typedef void (*ctor_fn_t)(void); 134 135 struct file_system_type; 136 137 /* Defined in init/main.c */ 138 extern int do_one_initcall(initcall_t fn); 139 extern char __initdata boot_command_line[]; 140 extern char *saved_command_line; 141 extern unsigned int saved_command_line_len; 142 extern unsigned int reset_devices; 143 144 /* used by init/main.c */ 145 void setup_arch(char **); 146 void prepare_namespace(void); 147 void __init init_rootfs(void); 148 149 void init_IRQ(void); 150 void time_init(void); 151 void poking_init(void); 152 void pgtable_cache_init(void); 153 154 extern initcall_entry_t __initcall_start[]; 155 extern initcall_entry_t __initcall0_start[]; 156 extern initcall_entry_t __initcall1_start[]; 157 extern initcall_entry_t __initcall2_start[]; 158 extern initcall_entry_t __initcall3_start[]; 159 extern initcall_entry_t __initcall4_start[]; 160 extern initcall_entry_t __initcall5_start[]; 161 extern initcall_entry_t __initcall6_start[]; 162 extern initcall_entry_t __initcall7_start[]; 163 extern initcall_entry_t __initcall_end[]; 164 165 extern struct file_system_type rootfs_fs_type; 166 167 extern bool rodata_enabled; 168 void mark_rodata_ro(void); 169 170 extern void (*late_time_init)(void); 171 172 extern bool initcall_debug; 173 174 #ifdef MODULE 175 extern struct module __this_module; 176 #define THIS_MODULE (&__this_module) 177 #else 178 #define THIS_MODULE ((struct module *)0) 179 #endif 180 181 #endif 182 183 #ifndef MODULE 184 185 #ifndef __ASSEMBLY__ 186 187 /* 188 * initcalls are now grouped by functionality into separate 189 * subsections. Ordering inside the subsections is determined 190 * by link order. 191 * For backwards compatibility, initcall() puts the call in 192 * the device init subsection. 193 * 194 * The `id' arg to __define_initcall() is needed so that multiple initcalls 195 * can point at the same handler without causing duplicate-symbol build errors. 196 * 197 * Initcalls are run by placing pointers in initcall sections that the 198 * kernel iterates at runtime. The linker can do dead code / data elimination 199 * and remove that completely, so the initcall sections have to be marked 200 * as KEEP() in the linker script. 201 */ 202 203 /* Format: <modname>__<counter>_<line>_<fn> */ 204 #define __initcall_id(fn) \ 205 __PASTE(__KBUILD_MODNAME, \ 206 __PASTE(__, \ 207 __PASTE(__COUNTER__, \ 208 __PASTE(_, \ 209 __PASTE(__LINE__, \ 210 __PASTE(_, fn)))))) 211 212 /* Format: __<prefix>__<iid><id> */ 213 #define __initcall_name(prefix, __iid, id) \ 214 __PASTE(__, \ 215 __PASTE(prefix, \ 216 __PASTE(__, \ 217 __PASTE(__iid, id)))) 218 219 #ifdef CONFIG_LTO_CLANG 220 /* 221 * With LTO, the compiler doesn't necessarily obey link order for 222 * initcalls. In order to preserve the correct order, we add each 223 * variable into its own section and generate a linker script (in 224 * scripts/link-vmlinux.sh) to specify the order of the sections. 225 */ 226 #define __initcall_section(__sec, __iid) \ 227 #__sec ".init.." #__iid 228 229 /* 230 * With LTO, the compiler can rename static functions to avoid 231 * global naming collisions. We use a global stub function for 232 * initcalls to create a stable symbol name whose address can be 233 * taken in inline assembly when PREL32 relocations are used. 234 */ 235 #define __initcall_stub(fn, __iid, id) \ 236 __initcall_name(initstub, __iid, id) 237 238 #define __define_initcall_stub(__stub, fn) \ 239 int __init __stub(void); \ 240 int __init __stub(void) \ 241 { \ 242 return fn(); \ 243 } \ 244 __ADDRESSABLE(__stub) 245 #else 246 #define __initcall_section(__sec, __iid) \ 247 #__sec ".init" 248 249 #define __initcall_stub(fn, __iid, id) fn 250 251 #define __define_initcall_stub(__stub, fn) \ 252 __ADDRESSABLE(fn) 253 #endif 254 255 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 256 #define ____define_initcall(fn, __stub, __name, __sec) \ 257 __define_initcall_stub(__stub, fn) \ 258 asm(".section \"" __sec "\", \"a\" \n" \ 259 __stringify(__name) ": \n" \ 260 ".long " __stringify(__stub) " - . \n" \ 261 ".previous \n"); \ 262 static_assert(__same_type(initcall_t, &fn)); 263 #else 264 #define ____define_initcall(fn, __unused, __name, __sec) \ 265 static initcall_t __name __used \ 266 __attribute__((__section__(__sec))) = fn; 267 #endif 268 269 #define __unique_initcall(fn, id, __sec, __iid) \ 270 ____define_initcall(fn, \ 271 __initcall_stub(fn, __iid, id), \ 272 __initcall_name(initcall, __iid, id), \ 273 __initcall_section(__sec, __iid)) 274 275 #define ___define_initcall(fn, id, __sec) \ 276 __unique_initcall(fn, id, __sec, __initcall_id(fn)) 277 278 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id) 279 280 /* 281 * Early initcalls run before initializing SMP. 282 * 283 * Only for built-in code, not modules. 284 */ 285 #define early_initcall(fn) __define_initcall(fn, early) 286 287 /* 288 * A "pure" initcall has no dependencies on anything else, and purely 289 * initializes variables that couldn't be statically initialized. 290 * 291 * This only exists for built-in code, not for modules. 292 * Keep main.c:initcall_level_names[] in sync. 293 */ 294 #define pure_initcall(fn) __define_initcall(fn, 0) 295 296 #define core_initcall(fn) __define_initcall(fn, 1) 297 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 298 #define postcore_initcall(fn) __define_initcall(fn, 2) 299 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 300 #define arch_initcall(fn) __define_initcall(fn, 3) 301 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 302 #define subsys_initcall(fn) __define_initcall(fn, 4) 303 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 304 #define fs_initcall(fn) __define_initcall(fn, 5) 305 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 306 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 307 #define device_initcall(fn) __define_initcall(fn, 6) 308 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 309 #define late_initcall(fn) __define_initcall(fn, 7) 310 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 311 312 #define __initcall(fn) device_initcall(fn) 313 314 #define __exitcall(fn) \ 315 static exitcall_t __exitcall_##fn __exit_call = fn 316 317 #define console_initcall(fn) ___define_initcall(fn, con, .con_initcall) 318 319 struct obs_kernel_param { 320 const char *str; 321 int (*setup_func)(char *); 322 int early; 323 }; 324 325 extern const struct obs_kernel_param __setup_start[], __setup_end[]; 326 327 /* 328 * Only for really core code. See moduleparam.h for the normal way. 329 * 330 * Force the alignment so the compiler doesn't space elements of the 331 * obs_kernel_param "array" too far apart in .init.setup. 332 */ 333 #define __setup_param(str, unique_id, fn, early) \ 334 static const char __setup_str_##unique_id[] __initconst \ 335 __aligned(1) = str; \ 336 static struct obs_kernel_param __setup_##unique_id \ 337 __used __section(".init.setup") \ 338 __aligned(__alignof__(struct obs_kernel_param)) \ 339 = { __setup_str_##unique_id, fn, early } 340 341 /* 342 * NOTE: __setup functions return values: 343 * @fn returns 1 (or non-zero) if the option argument is "handled" 344 * and returns 0 if the option argument is "not handled". 345 */ 346 #define __setup(str, fn) \ 347 __setup_param(str, fn, fn, 0) 348 349 /* 350 * NOTE: @fn is as per module_param, not __setup! 351 * I.e., @fn returns 0 for no error or non-zero for error 352 * (possibly @fn returns a -errno value, but it does not matter). 353 * Emits warning if @fn returns non-zero. 354 */ 355 #define early_param(str, fn) \ 356 __setup_param(str, fn, fn, 1) 357 358 #define early_param_on_off(str_on, str_off, var, config) \ 359 \ 360 int var = IS_ENABLED(config); \ 361 \ 362 static int __init parse_##var##_on(char *arg) \ 363 { \ 364 var = 1; \ 365 return 0; \ 366 } \ 367 early_param(str_on, parse_##var##_on); \ 368 \ 369 static int __init parse_##var##_off(char *arg) \ 370 { \ 371 var = 0; \ 372 return 0; \ 373 } \ 374 early_param(str_off, parse_##var##_off) 375 376 /* Relies on boot_command_line being set */ 377 void __init parse_early_param(void); 378 void __init parse_early_options(char *cmdline); 379 #endif /* __ASSEMBLY__ */ 380 381 #else /* MODULE */ 382 383 #define __setup_param(str, unique_id, fn) /* nothing */ 384 #define __setup(str, func) /* nothing */ 385 #endif 386 387 /* Data marked not to be saved by software suspend */ 388 #define __nosavedata __section(".data..nosave") 389 390 #ifdef MODULE 391 #define __exit_p(x) x 392 #else 393 #define __exit_p(x) NULL 394 #endif 395 396 #endif /* _LINUX_INIT_H */ 397