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 /* compatibility defines */ 81 #define __init_refok __ref 82 #define __initdata_refok __refdata 83 #define __exit_refok __ref 84 85 86 #ifdef MODULE 87 #define __exitused 88 #else 89 #define __exitused __used 90 #endif 91 92 #define __exit __section(.exit.text) __exitused __cold notrace 93 94 /* Used for MEMORY_HOTPLUG */ 95 #define __meminit __section(.meminit.text) __cold notrace 96 #define __meminitdata __section(.meminit.data) 97 #define __meminitconst __constsection(.meminit.rodata) 98 #define __memexit __section(.memexit.text) __exitused __cold notrace 99 #define __memexitdata __section(.memexit.data) 100 #define __memexitconst __constsection(.memexit.rodata) 101 102 /* For assembly routines */ 103 #define __HEAD .section ".head.text","ax" 104 #define __INIT .section ".init.text","ax" 105 #define __FINIT .previous 106 107 #define __INITDATA .section ".init.data","aw",%progbits 108 #define __INITRODATA .section ".init.rodata","a",%progbits 109 #define __FINITDATA .previous 110 111 #define __MEMINIT .section ".meminit.text", "ax" 112 #define __MEMINITDATA .section ".meminit.data", "aw" 113 #define __MEMINITRODATA .section ".meminit.rodata", "a" 114 115 /* silence warnings when references are OK */ 116 #define __REF .section ".ref.text", "ax" 117 #define __REFDATA .section ".ref.data", "aw" 118 #define __REFCONST .section ".ref.rodata", "a" 119 120 #ifndef __ASSEMBLY__ 121 /* 122 * Used for initialization calls.. 123 */ 124 typedef int (*initcall_t)(void); 125 typedef void (*exitcall_t)(void); 126 127 extern initcall_t __con_initcall_start[], __con_initcall_end[]; 128 extern initcall_t __security_initcall_start[], __security_initcall_end[]; 129 130 /* Used for contructor calls. */ 131 typedef void (*ctor_fn_t)(void); 132 133 /* Defined in init/main.c */ 134 extern int do_one_initcall(initcall_t fn); 135 extern char __initdata boot_command_line[]; 136 extern char *saved_command_line; 137 extern unsigned int reset_devices; 138 139 /* used by init/main.c */ 140 void setup_arch(char **); 141 void prepare_namespace(void); 142 void __init load_default_modules(void); 143 int __init init_rootfs(void); 144 145 #ifdef CONFIG_DEBUG_RODATA 146 void mark_rodata_ro(void); 147 #endif 148 149 extern void (*late_time_init)(void); 150 151 extern bool initcall_debug; 152 153 #endif 154 155 #ifndef MODULE 156 157 #ifndef __ASSEMBLY__ 158 159 #ifdef CONFIG_LTO 160 /* Work around a LTO gcc problem: when there is no reference to a variable 161 * in a module it will be moved to the end of the program. This causes 162 * reordering of initcalls which the kernel does not like. 163 * Add a dummy reference function to avoid this. The function is 164 * deleted by the linker. 165 */ 166 #define LTO_REFERENCE_INITCALL(x) \ 167 ; /* yes this is needed */ \ 168 static __used __exit void *reference_##x(void) \ 169 { \ 170 return &x; \ 171 } 172 #else 173 #define LTO_REFERENCE_INITCALL(x) 174 #endif 175 176 /* initcalls are now grouped by functionality into separate 177 * subsections. Ordering inside the subsections is determined 178 * by link order. 179 * For backwards compatibility, initcall() puts the call in 180 * the device init subsection. 181 * 182 * The `id' arg to __define_initcall() is needed so that multiple initcalls 183 * can point at the same handler without causing duplicate-symbol build errors. 184 */ 185 186 #define __define_initcall(fn, id) \ 187 static initcall_t __initcall_##fn##id __used \ 188 __attribute__((__section__(".initcall" #id ".init"))) = fn; \ 189 LTO_REFERENCE_INITCALL(__initcall_##fn##id) 190 191 /* 192 * Early initcalls run before initializing SMP. 193 * 194 * Only for built-in code, not modules. 195 */ 196 #define early_initcall(fn) __define_initcall(fn, early) 197 198 /* 199 * A "pure" initcall has no dependencies on anything else, and purely 200 * initializes variables that couldn't be statically initialized. 201 * 202 * This only exists for built-in code, not for modules. 203 * Keep main.c:initcall_level_names[] in sync. 204 */ 205 #define pure_initcall(fn) __define_initcall(fn, 0) 206 207 #define core_initcall(fn) __define_initcall(fn, 1) 208 #define core_initcall_sync(fn) __define_initcall(fn, 1s) 209 #define postcore_initcall(fn) __define_initcall(fn, 2) 210 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s) 211 #define arch_initcall(fn) __define_initcall(fn, 3) 212 #define arch_initcall_sync(fn) __define_initcall(fn, 3s) 213 #define subsys_initcall(fn) __define_initcall(fn, 4) 214 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s) 215 #define fs_initcall(fn) __define_initcall(fn, 5) 216 #define fs_initcall_sync(fn) __define_initcall(fn, 5s) 217 #define rootfs_initcall(fn) __define_initcall(fn, rootfs) 218 #define device_initcall(fn) __define_initcall(fn, 6) 219 #define device_initcall_sync(fn) __define_initcall(fn, 6s) 220 #define late_initcall(fn) __define_initcall(fn, 7) 221 #define late_initcall_sync(fn) __define_initcall(fn, 7s) 222 223 #define __initcall(fn) device_initcall(fn) 224 225 #define __exitcall(fn) \ 226 static exitcall_t __exitcall_##fn __exit_call = fn 227 228 #define console_initcall(fn) \ 229 static initcall_t __initcall_##fn \ 230 __used __section(.con_initcall.init) = fn 231 232 #define security_initcall(fn) \ 233 static initcall_t __initcall_##fn \ 234 __used __section(.security_initcall.init) = fn 235 236 struct obs_kernel_param { 237 const char *str; 238 int (*setup_func)(char *); 239 int early; 240 }; 241 242 /* 243 * Only for really core code. See moduleparam.h for the normal way. 244 * 245 * Force the alignment so the compiler doesn't space elements of the 246 * obs_kernel_param "array" too far apart in .init.setup. 247 */ 248 #define __setup_param(str, unique_id, fn, early) \ 249 static const char __setup_str_##unique_id[] __initconst \ 250 __aligned(1) = str; \ 251 static struct obs_kernel_param __setup_##unique_id \ 252 __used __section(.init.setup) \ 253 __attribute__((aligned((sizeof(long))))) \ 254 = { __setup_str_##unique_id, fn, early } 255 256 #define __setup(str, fn) \ 257 __setup_param(str, fn, fn, 0) 258 259 /* 260 * NOTE: fn is as per module_param, not __setup! 261 * Emits warning if fn returns non-zero. 262 */ 263 #define early_param(str, fn) \ 264 __setup_param(str, fn, fn, 1) 265 266 #define early_param_on_off(str_on, str_off, var, config) \ 267 \ 268 int var = IS_ENABLED(config); \ 269 \ 270 static int __init parse_##var##_on(char *arg) \ 271 { \ 272 var = 1; \ 273 return 0; \ 274 } \ 275 __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1); \ 276 \ 277 static int __init parse_##var##_off(char *arg) \ 278 { \ 279 var = 0; \ 280 return 0; \ 281 } \ 282 __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1) 283 284 /* Relies on boot_command_line being set */ 285 void __init parse_early_param(void); 286 void __init parse_early_options(char *cmdline); 287 #endif /* __ASSEMBLY__ */ 288 289 #else /* MODULE */ 290 291 #define __setup_param(str, unique_id, fn) /* nothing */ 292 #define __setup(str, func) /* nothing */ 293 #endif 294 295 /* Data marked not to be saved by software suspend */ 296 #define __nosavedata __section(.data..nosave) 297 298 #ifdef MODULE 299 #define __exit_p(x) x 300 #else 301 #define __exit_p(x) NULL 302 #endif 303 304 #endif /* _LINUX_INIT_H */ 305