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 /* Defined in init/main.c */ 141 extern int do_one_initcall(initcall_t fn); 142 extern char __initdata boot_command_line[]; 143 extern char *saved_command_line; 144 extern unsigned int reset_devices; 145 146 /* used by init/main.c */ 147 void setup_arch(char **); 148 void prepare_namespace(void); 149 void __init load_default_modules(void); 150 int __init init_rootfs(void); 151 152 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX) 153 extern bool rodata_enabled; 154 #endif 155 #ifdef CONFIG_STRICT_KERNEL_RWX 156 void mark_rodata_ro(void); 157 #endif 158 159 extern void (*late_time_init)(void); 160 161 extern bool initcall_debug; 162 163 #endif 164 165 #ifndef MODULE 166 167 #ifndef __ASSEMBLY__ 168 169 /* 170 * initcalls are now grouped by functionality into separate 171 * subsections. Ordering inside the subsections is determined 172 * by link order. 173 * For backwards compatibility, initcall() puts the call in 174 * the device init subsection. 175 * 176 * The `id' arg to __define_initcall() is needed so that multiple initcalls 177 * can point at the same handler without causing duplicate-symbol build errors. 178 * 179 * Initcalls are run by placing pointers in initcall sections that the 180 * kernel iterates at runtime. The linker can do dead code / data elimination 181 * and remove that completely, so the initcall sections have to be marked 182 * as KEEP() in the linker script. 183 */ 184 185 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 186 #define ___define_initcall(fn, id, __sec) \ 187 __ADDRESSABLE(fn) \ 188 asm(".section \"" #__sec ".init\", \"a\" \n" \ 189 "__initcall_" #fn #id ": \n" \ 190 ".long " #fn " - . \n" \ 191 ".previous \n"); 192 #else 193 #define ___define_initcall(fn, id, __sec) \ 194 static initcall_t __initcall_##fn##id __used \ 195 __attribute__((__section__(#__sec ".init"))) = fn; 196 #endif 197 198 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id) 199 200 /* 201 * Early initcalls run before initializing SMP. 202 * 203 * Only for built-in code, not modules. 204 */ 205 #define early_initcall(fn) __define_initcall(fn, early) 206 207 /* 208 * A "pure" initcall has no dependencies on anything else, and purely 209 * initializes variables that couldn't be statically initialized. 210 * 211 * This only exists for built-in code, not for modules. 212 * Keep main.c:initcall_level_names[] in sync. 213 */ 214 #define pure_initcall(fn) __define_initcall(fn, 0) 215 216 #define core_initcall(fn) __define_initcall(fn, 1) 217 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 218 #define postcore_initcall(fn) __define_initcall(fn, 2) 219 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 220 #define arch_initcall(fn) __define_initcall(fn, 3) 221 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 222 #define subsys_initcall(fn) __define_initcall(fn, 4) 223 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 224 #define fs_initcall(fn) __define_initcall(fn, 5) 225 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 226 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 227 #define device_initcall(fn) __define_initcall(fn, 6) 228 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 229 #define late_initcall(fn) __define_initcall(fn, 7) 230 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 231 232 #define __initcall(fn) device_initcall(fn) 233 234 #define __exitcall(fn) \ 235 static exitcall_t __exitcall_##fn __exit_call = fn 236 237 #define console_initcall(fn) ___define_initcall(fn,, .con_initcall) 238 239 struct obs_kernel_param { 240 const char *str; 241 int (*setup_func)(char *); 242 int early; 243 }; 244 245 /* 246 * Only for really core code. See moduleparam.h for the normal way. 247 * 248 * Force the alignment so the compiler doesn't space elements of the 249 * obs_kernel_param "array" too far apart in .init.setup. 250 */ 251 #define __setup_param(str, unique_id, fn, early) \ 252 static const char __setup_str_##unique_id[] __initconst \ 253 __aligned(1) = str; \ 254 static struct obs_kernel_param __setup_##unique_id \ 255 __used __section(.init.setup) \ 256 __attribute__((aligned((sizeof(long))))) \ 257 = { __setup_str_##unique_id, fn, early } 258 259 #define __setup(str, fn) \ 260 __setup_param(str, fn, fn, 0) 261 262 /* 263 * NOTE: fn is as per module_param, not __setup! 264 * Emits warning if fn returns non-zero. 265 */ 266 #define early_param(str, fn) \ 267 __setup_param(str, fn, fn, 1) 268 269 #define early_param_on_off(str_on, str_off, var, config) \ 270 \ 271 int var = IS_ENABLED(config); \ 272 \ 273 static int __init parse_##var##_on(char *arg) \ 274 { \ 275 var = 1; \ 276 return 0; \ 277 } \ 278 __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1); \ 279 \ 280 static int __init parse_##var##_off(char *arg) \ 281 { \ 282 var = 0; \ 283 return 0; \ 284 } \ 285 __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1) 286 287 /* Relies on boot_command_line being set */ 288 void __init parse_early_param(void); 289 void __init parse_early_options(char *cmdline); 290 #endif /* __ASSEMBLY__ */ 291 292 #else /* MODULE */ 293 294 #define __setup_param(str, unique_id, fn) /* nothing */ 295 #define __setup(str, func) /* nothing */ 296 #endif 297 298 /* Data marked not to be saved by software suspend */ 299 #define __nosavedata __section(.data..nosave) 300 301 #ifdef MODULE 302 #define __exit_p(x) x 303 #else 304 #define __exit_p(x) NULL 305 #endif 306 307 #endif /* _LINUX_INIT_H */ 308