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 __inittrace __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 #define __inittrace notrace 73 #else 74 #define __exitused __used 75 #define __inittrace 76 #endif 77 78 #define __exit __section(.exit.text) __exitused __cold notrace 79 80 /* Used for MEMORY_HOTPLUG */ 81 #define __meminit __section(.meminit.text) __cold notrace \ 82 __latent_entropy 83 #define __meminitdata __section(.meminit.data) 84 #define __meminitconst __section(.meminit.rodata) 85 #define __memexit __section(.memexit.text) __exitused __cold notrace 86 #define __memexitdata __section(.memexit.data) 87 #define __memexitconst __section(.memexit.rodata) 88 89 /* For assembly routines */ 90 #define __HEAD .section ".head.text","ax" 91 #define __INIT .section ".init.text","ax" 92 #define __FINIT .previous 93 94 #define __INITDATA .section ".init.data","aw",%progbits 95 #define __INITRODATA .section ".init.rodata","a",%progbits 96 #define __FINITDATA .previous 97 98 #define __MEMINIT .section ".meminit.text", "ax" 99 #define __MEMINITDATA .section ".meminit.data", "aw" 100 #define __MEMINITRODATA .section ".meminit.rodata", "a" 101 102 /* silence warnings when references are OK */ 103 #define __REF .section ".ref.text", "ax" 104 #define __REFDATA .section ".ref.data", "aw" 105 #define __REFCONST .section ".ref.rodata", "a" 106 107 #ifndef __ASSEMBLY__ 108 /* 109 * Used for initialization calls.. 110 */ 111 typedef int (*initcall_t)(void); 112 typedef void (*exitcall_t)(void); 113 114 extern initcall_t __con_initcall_start[], __con_initcall_end[]; 115 extern initcall_t __security_initcall_start[], __security_initcall_end[]; 116 117 /* Used for contructor calls. */ 118 typedef void (*ctor_fn_t)(void); 119 120 /* Defined in init/main.c */ 121 extern int do_one_initcall(initcall_t fn); 122 extern char __initdata boot_command_line[]; 123 extern char *saved_command_line; 124 extern unsigned int reset_devices; 125 126 /* used by init/main.c */ 127 void setup_arch(char **); 128 void prepare_namespace(void); 129 void __init load_default_modules(void); 130 int __init init_rootfs(void); 131 132 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX) 133 extern bool rodata_enabled; 134 #endif 135 #ifdef CONFIG_STRICT_KERNEL_RWX 136 void mark_rodata_ro(void); 137 #endif 138 139 extern void (*late_time_init)(void); 140 141 extern bool initcall_debug; 142 143 #endif 144 145 #ifndef MODULE 146 147 #ifndef __ASSEMBLY__ 148 149 /* 150 * initcalls are now grouped by functionality into separate 151 * subsections. Ordering inside the subsections is determined 152 * by link order. 153 * For backwards compatibility, initcall() puts the call in 154 * the device init subsection. 155 * 156 * The `id' arg to __define_initcall() is needed so that multiple initcalls 157 * can point at the same handler without causing duplicate-symbol build errors. 158 * 159 * Initcalls are run by placing pointers in initcall sections that the 160 * kernel iterates at runtime. The linker can do dead code / data elimination 161 * and remove that completely, so the initcall sections have to be marked 162 * as KEEP() in the linker script. 163 */ 164 165 #define __define_initcall(fn, id) \ 166 static initcall_t __initcall_##fn##id __used \ 167 __attribute__((__section__(".initcall" #id ".init"))) = fn; 168 169 /* 170 * Early initcalls run before initializing SMP. 171 * 172 * Only for built-in code, not modules. 173 */ 174 #define early_initcall(fn) __define_initcall(fn, early) 175 176 /* 177 * A "pure" initcall has no dependencies on anything else, and purely 178 * initializes variables that couldn't be statically initialized. 179 * 180 * This only exists for built-in code, not for modules. 181 * Keep main.c:initcall_level_names[] in sync. 182 */ 183 #define pure_initcall(fn) __define_initcall(fn, 0) 184 185 #define core_initcall(fn) __define_initcall(fn, 1) 186 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 187 #define postcore_initcall(fn) __define_initcall(fn, 2) 188 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 189 #define arch_initcall(fn) __define_initcall(fn, 3) 190 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 191 #define subsys_initcall(fn) __define_initcall(fn, 4) 192 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 193 #define fs_initcall(fn) __define_initcall(fn, 5) 194 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 195 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 196 #define device_initcall(fn) __define_initcall(fn, 6) 197 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 198 #define late_initcall(fn) __define_initcall(fn, 7) 199 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 200 201 #define __initcall(fn) device_initcall(fn) 202 203 #define __exitcall(fn) \ 204 static exitcall_t __exitcall_##fn __exit_call = fn 205 206 #define console_initcall(fn) \ 207 static initcall_t __initcall_##fn \ 208 __used __section(.con_initcall.init) = fn 209 210 #define security_initcall(fn) \ 211 static initcall_t __initcall_##fn \ 212 __used __section(.security_initcall.init) = fn 213 214 struct obs_kernel_param { 215 const char *str; 216 int (*setup_func)(char *); 217 int early; 218 }; 219 220 /* 221 * Only for really core code. See moduleparam.h for the normal way. 222 * 223 * Force the alignment so the compiler doesn't space elements of the 224 * obs_kernel_param "array" too far apart in .init.setup. 225 */ 226 #define __setup_param(str, unique_id, fn, early) \ 227 static const char __setup_str_##unique_id[] __initconst \ 228 __aligned(1) = str; \ 229 static struct obs_kernel_param __setup_##unique_id \ 230 __used __section(.init.setup) \ 231 __attribute__((aligned((sizeof(long))))) \ 232 = { __setup_str_##unique_id, fn, early } 233 234 #define __setup(str, fn) \ 235 __setup_param(str, fn, fn, 0) 236 237 /* 238 * NOTE: fn is as per module_param, not __setup! 239 * Emits warning if fn returns non-zero. 240 */ 241 #define early_param(str, fn) \ 242 __setup_param(str, fn, fn, 1) 243 244 #define early_param_on_off(str_on, str_off, var, config) \ 245 \ 246 int var = IS_ENABLED(config); \ 247 \ 248 static int __init parse_##var##_on(char *arg) \ 249 { \ 250 var = 1; \ 251 return 0; \ 252 } \ 253 __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1); \ 254 \ 255 static int __init parse_##var##_off(char *arg) \ 256 { \ 257 var = 0; \ 258 return 0; \ 259 } \ 260 __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1) 261 262 /* Relies on boot_command_line being set */ 263 void __init parse_early_param(void); 264 void __init parse_early_options(char *cmdline); 265 #endif /* __ASSEMBLY__ */ 266 267 #else /* MODULE */ 268 269 #define __setup_param(str, unique_id, fn) /* nothing */ 270 #define __setup(str, func) /* nothing */ 271 #endif 272 273 /* Data marked not to be saved by software suspend */ 274 #define __nosavedata __section(.data..nosave) 275 276 #ifdef MODULE 277 #define __exit_p(x) x 278 #else 279 #define __exit_p(x) NULL 280 #endif 281 282 #endif /* _LINUX_INIT_H */ 283