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