1 #ifndef _LINUX_INIT_H 2 #define _LINUX_INIT_H 3 4 #include <linux/compiler.h> 5 #include <linux/types.h> 6 7 /* These macros are used to mark some functions or 8 * initialized data (doesn't apply to uninitialized data) 9 * as `initialization' functions. The kernel can take this 10 * as hint that the function is used only during the initialization 11 * phase and free up used memory resources after 12 * 13 * Usage: 14 * For functions: 15 * 16 * You should add __init immediately before the function name, like: 17 * 18 * static void __init initme(int x, int y) 19 * { 20 * extern int z; z = x * y; 21 * } 22 * 23 * If the function has a prototype somewhere, you can also add 24 * __init between closing brace of the prototype and semicolon: 25 * 26 * extern int initialize_foobar_device(int, int, int) __init; 27 * 28 * For initialized data: 29 * You should insert __initdata or __initconst between the variable name 30 * and equal sign followed by value, e.g.: 31 * 32 * static int init_variable __initdata = 0; 33 * static const char linux_logo[] __initconst = { 0x32, 0x36, ... }; 34 * 35 * Don't forget to initialize data not at file scope, i.e. within a function, 36 * as gcc otherwise puts the data into the bss section and not into the init 37 * section. 38 */ 39 40 /* These are for everybody (although not all archs will actually 41 discard it in modules) */ 42 #define __init __section(.init.text) __cold notrace 43 #define __initdata __section(.init.data) 44 #define __initconst __constsection(.init.rodata) 45 #define __exitdata __section(.exit.data) 46 #define __exit_call __used __section(.exitcall.exit) 47 48 /* 49 * Some architecture have tool chains which do not handle rodata attributes 50 * correctly. For those disable special sections for const, so that other 51 * architectures can annotate correctly. 52 */ 53 #ifdef CONFIG_BROKEN_RODATA 54 #define __constsection(x) 55 #else 56 #define __constsection(x) __section(x) 57 #endif 58 59 /* 60 * modpost check for section mismatches during the kernel build. 61 * A section mismatch happens when there are references from a 62 * code or data section to an init section (both code or data). 63 * The init sections are (for most archs) discarded by the kernel 64 * when early init has completed so all such references are potential bugs. 65 * For exit sections the same issue exists. 66 * 67 * The following markers are used for the cases where the reference to 68 * the *init / *exit section (code or data) is valid and will teach 69 * modpost not to issue a warning. Intended semantics is that a code or 70 * data tagged __ref* can reference code or data from init section without 71 * producing a warning (of course, no warning does not mean code is 72 * correct, so optimally document why the __ref is needed and why it's OK). 73 * 74 * The markers follow same syntax rules as __init / __initdata. 75 */ 76 #define __ref __section(.ref.text) noinline 77 #define __refdata __section(.ref.data) 78 #define __refconst __constsection(.ref.rodata) 79 80 #ifdef MODULE 81 #define __exitused 82 #else 83 #define __exitused __used 84 #endif 85 86 #define __exit __section(.exit.text) __exitused __cold notrace 87 88 /* Used for MEMORY_HOTPLUG */ 89 #define __meminit __section(.meminit.text) __cold notrace 90 #define __meminitdata __section(.meminit.data) 91 #define __meminitconst __constsection(.meminit.rodata) 92 #define __memexit __section(.memexit.text) __exitused __cold notrace 93 #define __memexitdata __section(.memexit.data) 94 #define __memexitconst __constsection(.memexit.rodata) 95 96 /* For assembly routines */ 97 #define __HEAD .section ".head.text","ax" 98 #define __INIT .section ".init.text","ax" 99 #define __FINIT .previous 100 101 #define __INITDATA .section ".init.data","aw",%progbits 102 #define __INITRODATA .section ".init.rodata","a",%progbits 103 #define __FINITDATA .previous 104 105 #define __MEMINIT .section ".meminit.text", "ax" 106 #define __MEMINITDATA .section ".meminit.data", "aw" 107 #define __MEMINITRODATA .section ".meminit.rodata", "a" 108 109 /* silence warnings when references are OK */ 110 #define __REF .section ".ref.text", "ax" 111 #define __REFDATA .section ".ref.data", "aw" 112 #define __REFCONST .section ".ref.rodata", "a" 113 114 #ifndef __ASSEMBLY__ 115 /* 116 * Used for initialization calls.. 117 */ 118 typedef int (*initcall_t)(void); 119 typedef void (*exitcall_t)(void); 120 121 extern initcall_t __con_initcall_start[], __con_initcall_end[]; 122 extern initcall_t __security_initcall_start[], __security_initcall_end[]; 123 124 /* Used for contructor calls. */ 125 typedef void (*ctor_fn_t)(void); 126 127 /* Defined in init/main.c */ 128 extern int do_one_initcall(initcall_t fn); 129 extern char __initdata boot_command_line[]; 130 extern char *saved_command_line; 131 extern unsigned int reset_devices; 132 133 /* used by init/main.c */ 134 void setup_arch(char **); 135 void prepare_namespace(void); 136 void __init load_default_modules(void); 137 int __init init_rootfs(void); 138 139 #ifdef CONFIG_DEBUG_RODATA 140 void mark_rodata_ro(void); 141 #endif 142 143 extern void (*late_time_init)(void); 144 145 extern bool initcall_debug; 146 147 #endif 148 149 #ifndef MODULE 150 151 #ifndef __ASSEMBLY__ 152 153 #ifdef CONFIG_LTO 154 /* Work around a LTO gcc problem: when there is no reference to a variable 155 * in a module it will be moved to the end of the program. This causes 156 * reordering of initcalls which the kernel does not like. 157 * Add a dummy reference function to avoid this. The function is 158 * deleted by the linker. 159 */ 160 #define LTO_REFERENCE_INITCALL(x) \ 161 ; /* yes this is needed */ \ 162 static __used __exit void *reference_##x(void) \ 163 { \ 164 return &x; \ 165 } 166 #else 167 #define LTO_REFERENCE_INITCALL(x) 168 #endif 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 */ 179 180 #define __define_initcall(fn, id) \ 181 static initcall_t __initcall_##fn##id __used \ 182 __attribute__((__section__(".initcall" #id ".init"))) = fn; \ 183 LTO_REFERENCE_INITCALL(__initcall_##fn##id) 184 185 /* 186 * Early initcalls run before initializing SMP. 187 * 188 * Only for built-in code, not modules. 189 */ 190 #define early_initcall(fn) __define_initcall(fn, early) 191 192 /* 193 * A "pure" initcall has no dependencies on anything else, and purely 194 * initializes variables that couldn't be statically initialized. 195 * 196 * This only exists for built-in code, not for modules. 197 * Keep main.c:initcall_level_names[] in sync. 198 */ 199 #define pure_initcall(fn) __define_initcall(fn, 0) 200 201 #define core_initcall(fn) __define_initcall(fn, 1) 202 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 203 #define postcore_initcall(fn) __define_initcall(fn, 2) 204 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 205 #define arch_initcall(fn) __define_initcall(fn, 3) 206 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 207 #define subsys_initcall(fn) __define_initcall(fn, 4) 208 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 209 #define fs_initcall(fn) __define_initcall(fn, 5) 210 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 211 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 212 #define device_initcall(fn) __define_initcall(fn, 6) 213 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 214 #define late_initcall(fn) __define_initcall(fn, 7) 215 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 216 217 #define __initcall(fn) device_initcall(fn) 218 219 #define __exitcall(fn) \ 220 static exitcall_t __exitcall_##fn __exit_call = fn 221 222 #define console_initcall(fn) \ 223 static initcall_t __initcall_##fn \ 224 __used __section(.con_initcall.init) = fn 225 226 #define security_initcall(fn) \ 227 static initcall_t __initcall_##fn \ 228 __used __section(.security_initcall.init) = fn 229 230 struct obs_kernel_param { 231 const char *str; 232 int (*setup_func)(char *); 233 int early; 234 }; 235 236 /* 237 * Only for really core code. See moduleparam.h for the normal way. 238 * 239 * Force the alignment so the compiler doesn't space elements of the 240 * obs_kernel_param "array" too far apart in .init.setup. 241 */ 242 #define __setup_param(str, unique_id, fn, early) \ 243 static const char __setup_str_##unique_id[] __initconst \ 244 __aligned(1) = str; \ 245 static struct obs_kernel_param __setup_##unique_id \ 246 __used __section(.init.setup) \ 247 __attribute__((aligned((sizeof(long))))) \ 248 = { __setup_str_##unique_id, fn, early } 249 250 #define __setup(str, fn) \ 251 __setup_param(str, fn, fn, 0) 252 253 /* 254 * NOTE: fn is as per module_param, not __setup! 255 * Emits warning if fn returns non-zero. 256 */ 257 #define early_param(str, fn) \ 258 __setup_param(str, fn, fn, 1) 259 260 #define early_param_on_off(str_on, str_off, var, config) \ 261 \ 262 int var = IS_ENABLED(config); \ 263 \ 264 static int __init parse_##var##_on(char *arg) \ 265 { \ 266 var = 1; \ 267 return 0; \ 268 } \ 269 __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1); \ 270 \ 271 static int __init parse_##var##_off(char *arg) \ 272 { \ 273 var = 0; \ 274 return 0; \ 275 } \ 276 __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1) 277 278 /* Relies on boot_command_line being set */ 279 void __init parse_early_param(void); 280 void __init parse_early_options(char *cmdline); 281 #endif /* __ASSEMBLY__ */ 282 283 #else /* MODULE */ 284 285 #define __setup_param(str, unique_id, fn) /* nothing */ 286 #define __setup(str, func) /* nothing */ 287 #endif 288 289 /* Data marked not to be saved by software suspend */ 290 #define __nosavedata __section(.data..nosave) 291 292 #ifdef MODULE 293 #define __exit_p(x) x 294 #else 295 #define __exit_p(x) NULL 296 #endif 297 298 #endif /* _LINUX_INIT_H */ 299