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 __nocfi 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 contructor 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 reset_devices; 147 148 /* used by init/main.c */ 149 void setup_arch(char **); 150 void prepare_namespace(void); 151 void __init init_rootfs(void); 152 extern struct file_system_type rootfs_fs_type; 153 154 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX) 155 extern bool rodata_enabled; 156 #endif 157 #ifdef CONFIG_STRICT_KERNEL_RWX 158 void mark_rodata_ro(void); 159 #endif 160 161 extern void (*late_time_init)(void); 162 163 extern bool initcall_debug; 164 165 #endif 166 167 #ifndef MODULE 168 169 #ifndef __ASSEMBLY__ 170 171 /* 172 * initcalls are now grouped by functionality into separate 173 * subsections. Ordering inside the subsections is determined 174 * by link order. 175 * For backwards compatibility, initcall() puts the call in 176 * the device init subsection. 177 * 178 * The `id' arg to __define_initcall() is needed so that multiple initcalls 179 * can point at the same handler without causing duplicate-symbol build errors. 180 * 181 * Initcalls are run by placing pointers in initcall sections that the 182 * kernel iterates at runtime. The linker can do dead code / data elimination 183 * and remove that completely, so the initcall sections have to be marked 184 * as KEEP() in the linker script. 185 */ 186 187 /* Format: <modname>__<counter>_<line>_<fn> */ 188 #define __initcall_id(fn) \ 189 __PASTE(__KBUILD_MODNAME, \ 190 __PASTE(__, \ 191 __PASTE(__COUNTER__, \ 192 __PASTE(_, \ 193 __PASTE(__LINE__, \ 194 __PASTE(_, fn)))))) 195 196 /* Format: __<prefix>__<iid><id> */ 197 #define __initcall_name(prefix, __iid, id) \ 198 __PASTE(__, \ 199 __PASTE(prefix, \ 200 __PASTE(__, \ 201 __PASTE(__iid, id)))) 202 203 #ifdef CONFIG_LTO_CLANG 204 /* 205 * With LTO, the compiler doesn't necessarily obey link order for 206 * initcalls. In order to preserve the correct order, we add each 207 * variable into its own section and generate a linker script (in 208 * scripts/link-vmlinux.sh) to specify the order of the sections. 209 */ 210 #define __initcall_section(__sec, __iid) \ 211 #__sec ".init.." #__iid 212 213 /* 214 * With LTO, the compiler can rename static functions to avoid 215 * global naming collisions. We use a global stub function for 216 * initcalls to create a stable symbol name whose address can be 217 * taken in inline assembly when PREL32 relocations are used. 218 */ 219 #define __initcall_stub(fn, __iid, id) \ 220 __initcall_name(initstub, __iid, id) 221 222 #define __define_initcall_stub(__stub, fn) \ 223 int __init __cficanonical __stub(void); \ 224 int __init __cficanonical __stub(void) \ 225 { \ 226 return fn(); \ 227 } \ 228 __ADDRESSABLE(__stub) 229 #else 230 #define __initcall_section(__sec, __iid) \ 231 #__sec ".init" 232 233 #define __initcall_stub(fn, __iid, id) fn 234 235 #define __define_initcall_stub(__stub, fn) \ 236 __ADDRESSABLE(fn) 237 #endif 238 239 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 240 #define ____define_initcall(fn, __stub, __name, __sec) \ 241 __define_initcall_stub(__stub, fn) \ 242 asm(".section \"" __sec "\", \"a\" \n" \ 243 __stringify(__name) ": \n" \ 244 ".long " __stringify(__stub) " - . \n" \ 245 ".previous \n"); \ 246 static_assert(__same_type(initcall_t, &fn)); 247 #else 248 #define ____define_initcall(fn, __unused, __name, __sec) \ 249 static initcall_t __name __used \ 250 __attribute__((__section__(__sec))) = fn; 251 #endif 252 253 #define __unique_initcall(fn, id, __sec, __iid) \ 254 ____define_initcall(fn, \ 255 __initcall_stub(fn, __iid, id), \ 256 __initcall_name(initcall, __iid, id), \ 257 __initcall_section(__sec, __iid)) 258 259 #define ___define_initcall(fn, id, __sec) \ 260 __unique_initcall(fn, id, __sec, __initcall_id(fn)) 261 262 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id) 263 264 /* 265 * Early initcalls run before initializing SMP. 266 * 267 * Only for built-in code, not modules. 268 */ 269 #define early_initcall(fn) __define_initcall(fn, early) 270 271 /* 272 * A "pure" initcall has no dependencies on anything else, and purely 273 * initializes variables that couldn't be statically initialized. 274 * 275 * This only exists for built-in code, not for modules. 276 * Keep main.c:initcall_level_names[] in sync. 277 */ 278 #define pure_initcall(fn) __define_initcall(fn, 0) 279 280 #define core_initcall(fn) __define_initcall(fn, 1) 281 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 282 #define postcore_initcall(fn) __define_initcall(fn, 2) 283 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 284 #define arch_initcall(fn) __define_initcall(fn, 3) 285 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 286 #define subsys_initcall(fn) __define_initcall(fn, 4) 287 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 288 #define fs_initcall(fn) __define_initcall(fn, 5) 289 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 290 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 291 #define device_initcall(fn) __define_initcall(fn, 6) 292 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 293 #define late_initcall(fn) __define_initcall(fn, 7) 294 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 295 296 #define __initcall(fn) device_initcall(fn) 297 298 #define __exitcall(fn) \ 299 static exitcall_t __exitcall_##fn __exit_call = fn 300 301 #define console_initcall(fn) ___define_initcall(fn, con, .con_initcall) 302 303 struct obs_kernel_param { 304 const char *str; 305 int (*setup_func)(char *); 306 int early; 307 }; 308 309 /* 310 * Only for really core code. See moduleparam.h for the normal way. 311 * 312 * Force the alignment so the compiler doesn't space elements of the 313 * obs_kernel_param "array" too far apart in .init.setup. 314 */ 315 #define __setup_param(str, unique_id, fn, early) \ 316 static const char __setup_str_##unique_id[] __initconst \ 317 __aligned(1) = str; \ 318 static struct obs_kernel_param __setup_##unique_id \ 319 __used __section(".init.setup") \ 320 __aligned(__alignof__(struct obs_kernel_param)) \ 321 = { __setup_str_##unique_id, fn, early } 322 323 #define __setup(str, fn) \ 324 __setup_param(str, fn, fn, 0) 325 326 /* 327 * NOTE: fn is as per module_param, not __setup! 328 * Emits warning if fn returns non-zero. 329 */ 330 #define early_param(str, fn) \ 331 __setup_param(str, fn, fn, 1) 332 333 #define early_param_on_off(str_on, str_off, var, config) \ 334 \ 335 int var = IS_ENABLED(config); \ 336 \ 337 static int __init parse_##var##_on(char *arg) \ 338 { \ 339 var = 1; \ 340 return 0; \ 341 } \ 342 early_param(str_on, parse_##var##_on); \ 343 \ 344 static int __init parse_##var##_off(char *arg) \ 345 { \ 346 var = 0; \ 347 return 0; \ 348 } \ 349 early_param(str_off, parse_##var##_off) 350 351 /* Relies on boot_command_line being set */ 352 void __init parse_early_param(void); 353 void __init parse_early_options(char *cmdline); 354 #endif /* __ASSEMBLY__ */ 355 356 #else /* MODULE */ 357 358 #define __setup_param(str, unique_id, fn) /* nothing */ 359 #define __setup(str, func) /* nothing */ 360 #endif 361 362 /* Data marked not to be saved by software suspend */ 363 #define __nosavedata __section(".data..nosave") 364 365 #ifdef MODULE 366 #define __exit_p(x) x 367 #else 368 #define __exit_p(x) NULL 369 #endif 370 371 #endif /* _LINUX_INIT_H */ 372