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#define __MEMINIT .section ".meminit.text", "ax" 103#define __MEMINITDATA .section ".meminit.data", "aw" 104#define __MEMINITRODATA .section ".meminit.rodata", "a" 105 106/* silence warnings when references are OK */ 107#define __REF .section ".ref.text", "ax" 108#define __REFDATA .section ".ref.data", "aw" 109#define __REFCONST .section ".ref.rodata", "a" 110 111#ifndef __ASSEMBLY__ 112/* 113 * Used for initialization calls.. 114 */ 115typedef int (*initcall_t)(void); 116typedef void (*exitcall_t)(void); 117 118#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 119typedef int initcall_entry_t; 120 121static inline initcall_t initcall_from_entry(initcall_entry_t *entry) 122{ 123 return offset_to_ptr(entry); 124} 125#else 126typedef initcall_t initcall_entry_t; 127 128static inline initcall_t initcall_from_entry(initcall_entry_t *entry) 129{ 130 return *entry; 131} 132#endif 133 134extern initcall_entry_t __con_initcall_start[], __con_initcall_end[]; 135 136/* Used for constructor calls. */ 137typedef void (*ctor_fn_t)(void); 138 139struct file_system_type; 140 141/* Defined in init/main.c */ 142extern int do_one_initcall(initcall_t fn); 143extern char __initdata boot_command_line[]; 144extern char *saved_command_line; 145extern unsigned int saved_command_line_len; 146extern unsigned int reset_devices; 147 148/* used by init/main.c */ 149void setup_arch(char **); 150void prepare_namespace(void); 151void __init init_rootfs(void); 152 153void init_IRQ(void); 154void time_init(void); 155void poking_init(void); 156void pgtable_cache_init(void); 157 158extern initcall_entry_t __initcall_start[]; 159extern initcall_entry_t __initcall0_start[]; 160extern initcall_entry_t __initcall1_start[]; 161extern initcall_entry_t __initcall2_start[]; 162extern initcall_entry_t __initcall3_start[]; 163extern initcall_entry_t __initcall4_start[]; 164extern initcall_entry_t __initcall5_start[]; 165extern initcall_entry_t __initcall6_start[]; 166extern initcall_entry_t __initcall7_start[]; 167extern initcall_entry_t __initcall_end[]; 168 169extern struct file_system_type rootfs_fs_type; 170 171extern bool rodata_enabled; 172void mark_rodata_ro(void); 173 174extern void (*late_time_init)(void); 175 176extern bool initcall_debug; 177 178#ifdef MODULE 179extern struct module __this_module; 180#define THIS_MODULE (&__this_module) 181#else 182#define THIS_MODULE ((struct module *)0) 183#endif 184 185#endif 186 187#ifndef MODULE 188 189#ifndef __ASSEMBLY__ 190 191/* 192 * initcalls are now grouped by functionality into separate 193 * subsections. Ordering inside the subsections is determined 194 * by link order. 195 * For backwards compatibility, initcall() puts the call in 196 * the device init subsection. 197 * 198 * The `id' arg to __define_initcall() is needed so that multiple initcalls 199 * can point at the same handler without causing duplicate-symbol build errors. 200 * 201 * Initcalls are run by placing pointers in initcall sections that the 202 * kernel iterates at runtime. The linker can do dead code / data elimination 203 * and remove that completely, so the initcall sections have to be marked 204 * as KEEP() in the linker script. 205 */ 206 207/* Format: <modname>__<counter>_<line>_<fn> */ 208#define __initcall_id(fn) \ 209 __PASTE(__KBUILD_MODNAME, \ 210 __PASTE(__, \ 211 __PASTE(__COUNTER__, \ 212 __PASTE(_, \ 213 __PASTE(__LINE__, \ 214 __PASTE(_, fn)))))) 215 216/* Format: __<prefix>__<iid><id> */ 217#define __initcall_name(prefix, __iid, id) \ 218 __PASTE(__, \ 219 __PASTE(prefix, \ 220 __PASTE(__, \ 221 __PASTE(__iid, id)))) 222 223#ifdef CONFIG_LTO_CLANG 224/* 225 * With LTO, the compiler doesn't necessarily obey link order for 226 * initcalls. In order to preserve the correct order, we add each 227 * variable into its own section and generate a linker script (in 228 * scripts/link-vmlinux.sh) to specify the order of the sections. 229 */ 230#define __initcall_section(__sec, __iid) \ 231 #__sec ".init.." #__iid 232 233/* 234 * With LTO, the compiler can rename static functions to avoid 235 * global naming collisions. We use a global stub function for 236 * initcalls to create a stable symbol name whose address can be 237 * taken in inline assembly when PREL32 relocations are used. 238 */ 239#define __initcall_stub(fn, __iid, id) \ 240 __initcall_name(initstub, __iid, id) 241 242#define __define_initcall_stub(__stub, fn) \ 243 int __init __stub(void); \ 244 int __init __stub(void) \ 245 { \ 246 return fn(); \ 247 } \ 248 __ADDRESSABLE(__stub) 249#else 250#define __initcall_section(__sec, __iid) \ 251 #__sec ".init" 252 253#define __initcall_stub(fn, __iid, id) fn 254 255#define __define_initcall_stub(__stub, fn) \ 256 __ADDRESSABLE(fn) 257#endif 258 259#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 260#define ____define_initcall(fn, __stub, __name, __sec) \ 261 __define_initcall_stub(__stub, fn) \ 262 asm(".section \"" __sec "\", \"a\" \n" \ 263 __stringify(__name) ": \n" \ 264 ".long " __stringify(__stub) " - . \n" \ 265 ".previous \n"); \ 266 static_assert(__same_type(initcall_t, &fn)); 267#else 268#define ____define_initcall(fn, __unused, __name, __sec) \ 269 static initcall_t __name __used \ 270 __attribute__((__section__(__sec))) = fn; 271#endif 272 273#define __unique_initcall(fn, id, __sec, __iid) \ 274 ____define_initcall(fn, \ 275 __initcall_stub(fn, __iid, id), \ 276 __initcall_name(initcall, __iid, id), \ 277 __initcall_section(__sec, __iid)) 278 279#define ___define_initcall(fn, id, __sec) \ 280 __unique_initcall(fn, id, __sec, __initcall_id(fn)) 281 282#define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id) 283 284/* 285 * Early initcalls run before initializing SMP. 286 * 287 * Only for built-in code, not modules. 288 */ 289#define early_initcall(fn) __define_initcall(fn, early) 290 291/* 292 * A "pure" initcall has no dependencies on anything else, and purely 293 * initializes variables that couldn't be statically initialized. 294 * 295 * This only exists for built-in code, not for modules. 296 * Keep main.c:initcall_level_names[] in sync. 297 */ 298#define pure_initcall(fn) __define_initcall(fn, 0) 299 300#define core_initcall(fn) __define_initcall(fn, 1) 301#define core_initcall_sync(fn) __define_initcall(fn, 1s) 302#define postcore_initcall(fn) __define_initcall(fn, 2) 303#define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 304#define arch_initcall(fn) __define_initcall(fn, 3) 305#define arch_initcall_sync(fn) __define_initcall(fn, 3s) 306#define subsys_initcall(fn) __define_initcall(fn, 4) 307#define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 308#define fs_initcall(fn) __define_initcall(fn, 5) 309#define fs_initcall_sync(fn) __define_initcall(fn, 5s) 310#define rootfs_initcall(fn) __define_initcall(fn, rootfs) 311#define device_initcall(fn) __define_initcall(fn, 6) 312#define device_initcall_sync(fn) __define_initcall(fn, 6s) 313#define late_initcall(fn) __define_initcall(fn, 7) 314#define late_initcall_sync(fn) __define_initcall(fn, 7s) 315 316#define __initcall(fn) device_initcall(fn) 317 318#define __exitcall(fn) \ 319 static exitcall_t __exitcall_##fn __exit_call = fn 320 321#define console_initcall(fn) ___define_initcall(fn, con, .con_initcall) 322 323struct obs_kernel_param { 324 const char *str; 325 int (*setup_func)(char *); 326 int early; 327}; 328 329extern const struct obs_kernel_param __setup_start[], __setup_end[]; 330 331/* 332 * Only for really core code. See moduleparam.h for the normal way. 333 * 334 * Force the alignment so the compiler doesn't space elements of the 335 * obs_kernel_param "array" too far apart in .init.setup. 336 */ 337#define __setup_param(str, unique_id, fn, early) \ 338 static const char __setup_str_##unique_id[] __initconst \ 339 __aligned(1) = str; \ 340 static struct obs_kernel_param __setup_##unique_id \ 341 __used __section(".init.setup") \ 342 __aligned(__alignof__(struct obs_kernel_param)) \ 343 = { __setup_str_##unique_id, fn, early } 344 345/* 346 * NOTE: __setup functions return values: 347 * @fn returns 1 (or non-zero) if the option argument is "handled" 348 * and returns 0 if the option argument is "not handled". 349 */ 350#define __setup(str, fn) \ 351 __setup_param(str, fn, fn, 0) 352 353/* 354 * NOTE: @fn is as per module_param, not __setup! 355 * I.e., @fn returns 0 for no error or non-zero for error 356 * (possibly @fn returns a -errno value, but it does not matter). 357 * Emits warning if @fn returns non-zero. 358 */ 359#define early_param(str, fn) \ 360 __setup_param(str, fn, fn, 1) 361 362#define early_param_on_off(str_on, str_off, var, config) \ 363 \ 364 int var = IS_ENABLED(config); \ 365 \ 366 static int __init parse_##var##_on(char *arg) \ 367 { \ 368 var = 1; \ 369 return 0; \ 370 } \ 371 early_param(str_on, parse_##var##_on); \ 372 \ 373 static int __init parse_##var##_off(char *arg) \ 374 { \ 375 var = 0; \ 376 return 0; \ 377 } \ 378 early_param(str_off, parse_##var##_off) 379 380/* Relies on boot_command_line being set */ 381void __init parse_early_param(void); 382void __init parse_early_options(char *cmdline); 383#endif /* __ASSEMBLY__ */ 384 385#else /* MODULE */ 386 387#define __setup_param(str, unique_id, fn) /* nothing */ 388#define __setup(str, func) /* nothing */ 389#endif 390 391/* Data marked not to be saved by software suspend */ 392#define __nosavedata __section(".data..nosave") 393 394#ifdef MODULE 395#define __exit_p(x) x 396#else 397#define __exit_p(x) NULL 398#endif 399 400#endif /* _LINUX_INIT_H */ 401