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 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 #else 213 #define __initcall_section(__sec, __iid) \ 214 #__sec ".init" 215 #endif 216 217 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 218 #define ____define_initcall(fn, __name, __sec) \ 219 __ADDRESSABLE(fn) \ 220 asm(".section \"" __sec "\", \"a\" \n" \ 221 __stringify(__name) ": \n" \ 222 ".long " #fn " - . \n" \ 223 ".previous \n"); 224 #else 225 #define ____define_initcall(fn, __name, __sec) \ 226 static initcall_t __name __used \ 227 __attribute__((__section__(__sec))) = fn; 228 #endif 229 230 #define __unique_initcall(fn, id, __sec, __iid) \ 231 ____define_initcall(fn, \ 232 __initcall_name(initcall, __iid, id), \ 233 __initcall_section(__sec, __iid)) 234 235 #define ___define_initcall(fn, id, __sec) \ 236 __unique_initcall(fn, id, __sec, __initcall_id(fn)) 237 238 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id) 239 240 /* 241 * Early initcalls run before initializing SMP. 242 * 243 * Only for built-in code, not modules. 244 */ 245 #define early_initcall(fn) __define_initcall(fn, early) 246 247 /* 248 * A "pure" initcall has no dependencies on anything else, and purely 249 * initializes variables that couldn't be statically initialized. 250 * 251 * This only exists for built-in code, not for modules. 252 * Keep main.c:initcall_level_names[] in sync. 253 */ 254 #define pure_initcall(fn) __define_initcall(fn, 0) 255 256 #define core_initcall(fn) __define_initcall(fn, 1) 257 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 258 #define postcore_initcall(fn) __define_initcall(fn, 2) 259 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 260 #define arch_initcall(fn) __define_initcall(fn, 3) 261 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 262 #define subsys_initcall(fn) __define_initcall(fn, 4) 263 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 264 #define fs_initcall(fn) __define_initcall(fn, 5) 265 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 266 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 267 #define device_initcall(fn) __define_initcall(fn, 6) 268 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 269 #define late_initcall(fn) __define_initcall(fn, 7) 270 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 271 272 #define __initcall(fn) device_initcall(fn) 273 274 #define __exitcall(fn) \ 275 static exitcall_t __exitcall_##fn __exit_call = fn 276 277 #define console_initcall(fn) ___define_initcall(fn, con, .con_initcall) 278 279 struct obs_kernel_param { 280 const char *str; 281 int (*setup_func)(char *); 282 int early; 283 }; 284 285 /* 286 * Only for really core code. See moduleparam.h for the normal way. 287 * 288 * Force the alignment so the compiler doesn't space elements of the 289 * obs_kernel_param "array" too far apart in .init.setup. 290 */ 291 #define __setup_param(str, unique_id, fn, early) \ 292 static const char __setup_str_##unique_id[] __initconst \ 293 __aligned(1) = str; \ 294 static struct obs_kernel_param __setup_##unique_id \ 295 __used __section(".init.setup") \ 296 __aligned(__alignof__(struct obs_kernel_param)) \ 297 = { __setup_str_##unique_id, fn, early } 298 299 #define __setup(str, fn) \ 300 __setup_param(str, fn, fn, 0) 301 302 /* 303 * NOTE: fn is as per module_param, not __setup! 304 * Emits warning if fn returns non-zero. 305 */ 306 #define early_param(str, fn) \ 307 __setup_param(str, fn, fn, 1) 308 309 #define early_param_on_off(str_on, str_off, var, config) \ 310 \ 311 int var = IS_ENABLED(config); \ 312 \ 313 static int __init parse_##var##_on(char *arg) \ 314 { \ 315 var = 1; \ 316 return 0; \ 317 } \ 318 __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1); \ 319 \ 320 static int __init parse_##var##_off(char *arg) \ 321 { \ 322 var = 0; \ 323 return 0; \ 324 } \ 325 __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1) 326 327 /* Relies on boot_command_line being set */ 328 void __init parse_early_param(void); 329 void __init parse_early_options(char *cmdline); 330 #endif /* __ASSEMBLY__ */ 331 332 #else /* MODULE */ 333 334 #define __setup_param(str, unique_id, fn) /* nothing */ 335 #define __setup(str, func) /* nothing */ 336 #endif 337 338 /* Data marked not to be saved by software suspend */ 339 #define __nosavedata __section(".data..nosave") 340 341 #ifdef MODULE 342 #define __exit_p(x) x 343 #else 344 #define __exit_p(x) NULL 345 #endif 346 347 #endif /* _LINUX_INIT_H */ 348