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 extern initcall_t __con_initcall_start[], __con_initcall_end[]; 120 extern initcall_t __security_initcall_start[], __security_initcall_end[]; 121 122 /* Used for contructor calls. */ 123 typedef void (*ctor_fn_t)(void); 124 125 /* Defined in init/main.c */ 126 extern int do_one_initcall(initcall_t fn); 127 extern char __initdata boot_command_line[]; 128 extern char *saved_command_line; 129 extern unsigned int reset_devices; 130 131 /* used by init/main.c */ 132 void setup_arch(char **); 133 void prepare_namespace(void); 134 void __init load_default_modules(void); 135 int __init init_rootfs(void); 136 137 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX) 138 extern bool rodata_enabled; 139 #endif 140 #ifdef CONFIG_STRICT_KERNEL_RWX 141 void mark_rodata_ro(void); 142 #endif 143 144 extern void (*late_time_init)(void); 145 146 extern bool initcall_debug; 147 148 #endif 149 150 #ifndef MODULE 151 152 #ifndef __ASSEMBLY__ 153 154 /* 155 * initcalls are now grouped by functionality into separate 156 * subsections. Ordering inside the subsections is determined 157 * by link order. 158 * For backwards compatibility, initcall() puts the call in 159 * the device init subsection. 160 * 161 * The `id' arg to __define_initcall() is needed so that multiple initcalls 162 * can point at the same handler without causing duplicate-symbol build errors. 163 * 164 * Initcalls are run by placing pointers in initcall sections that the 165 * kernel iterates at runtime. The linker can do dead code / data elimination 166 * and remove that completely, so the initcall sections have to be marked 167 * as KEEP() in the linker script. 168 */ 169 170 #define __define_initcall(fn, id) \ 171 static initcall_t __initcall_##fn##id __used \ 172 __attribute__((__section__(".initcall" #id ".init"))) = fn; 173 174 /* 175 * Early initcalls run before initializing SMP. 176 * 177 * Only for built-in code, not modules. 178 */ 179 #define early_initcall(fn) __define_initcall(fn, early) 180 181 /* 182 * A "pure" initcall has no dependencies on anything else, and purely 183 * initializes variables that couldn't be statically initialized. 184 * 185 * This only exists for built-in code, not for modules. 186 * Keep main.c:initcall_level_names[] in sync. 187 */ 188 #define pure_initcall(fn) __define_initcall(fn, 0) 189 190 #define core_initcall(fn) __define_initcall(fn, 1) 191 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 192 #define postcore_initcall(fn) __define_initcall(fn, 2) 193 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 194 #define arch_initcall(fn) __define_initcall(fn, 3) 195 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 196 #define subsys_initcall(fn) __define_initcall(fn, 4) 197 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 198 #define fs_initcall(fn) __define_initcall(fn, 5) 199 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 200 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 201 #define device_initcall(fn) __define_initcall(fn, 6) 202 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 203 #define late_initcall(fn) __define_initcall(fn, 7) 204 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 205 206 #define __initcall(fn) device_initcall(fn) 207 208 #define __exitcall(fn) \ 209 static exitcall_t __exitcall_##fn __exit_call = fn 210 211 #define console_initcall(fn) \ 212 static initcall_t __initcall_##fn \ 213 __used __section(.con_initcall.init) = fn 214 215 #define security_initcall(fn) \ 216 static initcall_t __initcall_##fn \ 217 __used __section(.security_initcall.init) = fn 218 219 struct obs_kernel_param { 220 const char *str; 221 int (*setup_func)(char *); 222 int early; 223 }; 224 225 /* 226 * Only for really core code. See moduleparam.h for the normal way. 227 * 228 * Force the alignment so the compiler doesn't space elements of the 229 * obs_kernel_param "array" too far apart in .init.setup. 230 */ 231 #define __setup_param(str, unique_id, fn, early) \ 232 static const char __setup_str_##unique_id[] __initconst \ 233 __aligned(1) = str; \ 234 static struct obs_kernel_param __setup_##unique_id \ 235 __used __section(.init.setup) \ 236 __attribute__((aligned((sizeof(long))))) \ 237 = { __setup_str_##unique_id, fn, early } 238 239 #define __setup(str, fn) \ 240 __setup_param(str, fn, fn, 0) 241 242 /* 243 * NOTE: fn is as per module_param, not __setup! 244 * Emits warning if fn returns non-zero. 245 */ 246 #define early_param(str, fn) \ 247 __setup_param(str, fn, fn, 1) 248 249 #define early_param_on_off(str_on, str_off, var, config) \ 250 \ 251 int var = IS_ENABLED(config); \ 252 \ 253 static int __init parse_##var##_on(char *arg) \ 254 { \ 255 var = 1; \ 256 return 0; \ 257 } \ 258 __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1); \ 259 \ 260 static int __init parse_##var##_off(char *arg) \ 261 { \ 262 var = 0; \ 263 return 0; \ 264 } \ 265 __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1) 266 267 /* Relies on boot_command_line being set */ 268 void __init parse_early_param(void); 269 void __init parse_early_options(char *cmdline); 270 #endif /* __ASSEMBLY__ */ 271 272 #else /* MODULE */ 273 274 #define __setup_param(str, unique_id, fn) /* nothing */ 275 #define __setup(str, func) /* nothing */ 276 #endif 277 278 /* Data marked not to be saved by software suspend */ 279 #define __nosavedata __section(.data..nosave) 280 281 #ifdef MODULE 282 #define __exit_p(x) x 283 #else 284 #define __exit_p(x) NULL 285 #endif 286 287 #endif /* _LINUX_INIT_H */ 288