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 /* These macros are used to mark some functions or 9 * initialized data (doesn't apply to uninitialized data) 10 * as `initialization' functions. The kernel can take this 11 * as hint that the function is used only during the initialization 12 * phase and free up used memory resources after 13 * 14 * Usage: 15 * For functions: 16 * 17 * You should add __init immediately before the function name, like: 18 * 19 * static void __init initme(int x, int y) 20 * { 21 * extern int z; z = x * y; 22 * } 23 * 24 * If the function has a prototype somewhere, you can also add 25 * __init between closing brace of the prototype and semicolon: 26 * 27 * extern int initialize_foobar_device(int, int, int) __init; 28 * 29 * For initialized data: 30 * You should insert __initdata or __initconst between the variable name 31 * and equal sign followed by value, e.g.: 32 * 33 * static int init_variable __initdata = 0; 34 * static const char linux_logo[] __initconst = { 0x32, 0x36, ... }; 35 * 36 * Don't forget to initialize data not at file scope, i.e. within a function, 37 * as gcc otherwise puts the data into the bss section and not into the init 38 * section. 39 */ 40 41 /* These are for everybody (although not all archs will actually 42 discard it in modules) */ 43 #define __init __section(.init.text) __cold __latent_entropy 44 #define __initdata __section(.init.data) 45 #define __initconst __section(.init.rodata) 46 #define __exitdata __section(.exit.data) 47 #define __exit_call __used __section(.exitcall.exit) 48 49 /* 50 * modpost check for section mismatches during the kernel build. 51 * A section mismatch happens when there are references from a 52 * code or data section to an init section (both code or data). 53 * The init sections are (for most archs) discarded by the kernel 54 * when early init has completed so all such references are potential bugs. 55 * For exit sections the same issue exists. 56 * 57 * The following markers are used for the cases where the reference to 58 * the *init / *exit section (code or data) is valid and will teach 59 * modpost not to issue a warning. Intended semantics is that a code or 60 * data tagged __ref* can reference code or data from init section without 61 * producing a warning (of course, no warning does not mean code is 62 * correct, so optimally document why the __ref is needed and why it's OK). 63 * 64 * The markers follow same syntax rules as __init / __initdata. 65 */ 66 #define __ref __section(.ref.text) noinline 67 #define __refdata __section(.ref.data) 68 #define __refconst __section(.ref.rodata) 69 70 #ifdef MODULE 71 #define __exitused 72 #else 73 #define __exitused __used 74 #endif 75 76 #define __exit __section(.exit.text) __exitused __cold notrace 77 78 /* Used for MEMORY_HOTPLUG */ 79 #define __meminit __section(.meminit.text) __cold notrace \ 80 __latent_entropy 81 #define __meminitdata __section(.meminit.data) 82 #define __meminitconst __section(.meminit.rodata) 83 #define __memexit __section(.memexit.text) __exitused __cold notrace 84 #define __memexitdata __section(.memexit.data) 85 #define __memexitconst __section(.memexit.rodata) 86 87 /* For assembly routines */ 88 #define __HEAD .section ".head.text","ax" 89 #define __INIT .section ".init.text","ax" 90 #define __FINIT .previous 91 92 #define __INITDATA .section ".init.data","aw",%progbits 93 #define __INITRODATA .section ".init.rodata","a",%progbits 94 #define __FINITDATA .previous 95 96 #define __MEMINIT .section ".meminit.text", "ax" 97 #define __MEMINITDATA .section ".meminit.data", "aw" 98 #define __MEMINITRODATA .section ".meminit.rodata", "a" 99 100 /* silence warnings when references are OK */ 101 #define __REF .section ".ref.text", "ax" 102 #define __REFDATA .section ".ref.data", "aw" 103 #define __REFCONST .section ".ref.rodata", "a" 104 105 #ifndef __ASSEMBLY__ 106 /* 107 * Used for initialization calls.. 108 */ 109 typedef int (*initcall_t)(void); 110 typedef void (*exitcall_t)(void); 111 112 extern initcall_t __con_initcall_start[], __con_initcall_end[]; 113 extern initcall_t __security_initcall_start[], __security_initcall_end[]; 114 115 /* Used for contructor calls. */ 116 typedef void (*ctor_fn_t)(void); 117 118 /* Defined in init/main.c */ 119 extern int do_one_initcall(initcall_t fn); 120 extern char __initdata boot_command_line[]; 121 extern char *saved_command_line; 122 extern unsigned int reset_devices; 123 124 /* used by init/main.c */ 125 void setup_arch(char **); 126 void prepare_namespace(void); 127 void __init load_default_modules(void); 128 int __init init_rootfs(void); 129 130 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX) 131 extern bool rodata_enabled; 132 #endif 133 #ifdef CONFIG_STRICT_KERNEL_RWX 134 void mark_rodata_ro(void); 135 #endif 136 137 extern void (*late_time_init)(void); 138 139 extern bool initcall_debug; 140 141 #endif 142 143 #ifndef MODULE 144 145 #ifndef __ASSEMBLY__ 146 147 /* 148 * initcalls are now grouped by functionality into separate 149 * subsections. Ordering inside the subsections is determined 150 * by link order. 151 * For backwards compatibility, initcall() puts the call in 152 * the device init subsection. 153 * 154 * The `id' arg to __define_initcall() is needed so that multiple initcalls 155 * can point at the same handler without causing duplicate-symbol build errors. 156 * 157 * Initcalls are run by placing pointers in initcall sections that the 158 * kernel iterates at runtime. The linker can do dead code / data elimination 159 * and remove that completely, so the initcall sections have to be marked 160 * as KEEP() in the linker script. 161 */ 162 163 #define __define_initcall(fn, id) \ 164 static initcall_t __initcall_##fn##id __used \ 165 __attribute__((__section__(".initcall" #id ".init"))) = fn; 166 167 /* 168 * Early initcalls run before initializing SMP. 169 * 170 * Only for built-in code, not modules. 171 */ 172 #define early_initcall(fn) __define_initcall(fn, early) 173 174 /* 175 * A "pure" initcall has no dependencies on anything else, and purely 176 * initializes variables that couldn't be statically initialized. 177 * 178 * This only exists for built-in code, not for modules. 179 * Keep main.c:initcall_level_names[] in sync. 180 */ 181 #define pure_initcall(fn) __define_initcall(fn, 0) 182 183 #define core_initcall(fn) __define_initcall(fn, 1) 184 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 185 #define postcore_initcall(fn) __define_initcall(fn, 2) 186 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 187 #define arch_initcall(fn) __define_initcall(fn, 3) 188 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 189 #define subsys_initcall(fn) __define_initcall(fn, 4) 190 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 191 #define fs_initcall(fn) __define_initcall(fn, 5) 192 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 193 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 194 #define device_initcall(fn) __define_initcall(fn, 6) 195 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 196 #define late_initcall(fn) __define_initcall(fn, 7) 197 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 198 199 #define __initcall(fn) device_initcall(fn) 200 201 #define __exitcall(fn) \ 202 static exitcall_t __exitcall_##fn __exit_call = fn 203 204 #define console_initcall(fn) \ 205 static initcall_t __initcall_##fn \ 206 __used __section(.con_initcall.init) = fn 207 208 #define security_initcall(fn) \ 209 static initcall_t __initcall_##fn \ 210 __used __section(.security_initcall.init) = fn 211 212 struct obs_kernel_param { 213 const char *str; 214 int (*setup_func)(char *); 215 int early; 216 }; 217 218 /* 219 * Only for really core code. See moduleparam.h for the normal way. 220 * 221 * Force the alignment so the compiler doesn't space elements of the 222 * obs_kernel_param "array" too far apart in .init.setup. 223 */ 224 #define __setup_param(str, unique_id, fn, early) \ 225 static const char __setup_str_##unique_id[] __initconst \ 226 __aligned(1) = str; \ 227 static struct obs_kernel_param __setup_##unique_id \ 228 __used __section(.init.setup) \ 229 __attribute__((aligned((sizeof(long))))) \ 230 = { __setup_str_##unique_id, fn, early } 231 232 #define __setup(str, fn) \ 233 __setup_param(str, fn, fn, 0) 234 235 /* 236 * NOTE: fn is as per module_param, not __setup! 237 * Emits warning if fn returns non-zero. 238 */ 239 #define early_param(str, fn) \ 240 __setup_param(str, fn, fn, 1) 241 242 #define early_param_on_off(str_on, str_off, var, config) \ 243 \ 244 int var = IS_ENABLED(config); \ 245 \ 246 static int __init parse_##var##_on(char *arg) \ 247 { \ 248 var = 1; \ 249 return 0; \ 250 } \ 251 __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1); \ 252 \ 253 static int __init parse_##var##_off(char *arg) \ 254 { \ 255 var = 0; \ 256 return 0; \ 257 } \ 258 __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1) 259 260 /* Relies on boot_command_line being set */ 261 void __init parse_early_param(void); 262 void __init parse_early_options(char *cmdline); 263 #endif /* __ASSEMBLY__ */ 264 265 #else /* MODULE */ 266 267 #define __setup_param(str, unique_id, fn) /* nothing */ 268 #define __setup(str, func) /* nothing */ 269 #endif 270 271 /* Data marked not to be saved by software suspend */ 272 #define __nosavedata __section(.data..nosave) 273 274 #ifdef MODULE 275 #define __exit_p(x) x 276 #else 277 #define __exit_p(x) NULL 278 #endif 279 280 #endif /* _LINUX_INIT_H */ 281