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 __section(.init.rodata) 45 #define __exitdata __section(.exit.data) 46 #define __exit_call __used __section(.exitcall.exit) 47 48 /* 49 * modpost check for section mismatches during the kernel build. 50 * A section mismatch happens when there are references from a 51 * code or data section to an init section (both code or data). 52 * The init sections are (for most archs) discarded by the kernel 53 * when early init has completed so all such references are potential bugs. 54 * For exit sections the same issue exists. 55 * 56 * The following markers are used for the cases where the reference to 57 * the *init / *exit section (code or data) is valid and will teach 58 * modpost not to issue a warning. Intended semantics is that a code or 59 * data tagged __ref* can reference code or data from init section without 60 * producing a warning (of course, no warning does not mean code is 61 * correct, so optimally document why the __ref is needed and why it's OK). 62 * 63 * The markers follow same syntax rules as __init / __initdata. 64 */ 65 #define __ref __section(.ref.text) noinline 66 #define __refdata __section(.ref.data) 67 #define __refconst __section(.ref.rodata) 68 69 #ifdef MODULE 70 #define __exitused 71 #else 72 #define __exitused __used 73 #endif 74 75 #define __exit __section(.exit.text) __exitused __cold notrace 76 77 /* Used for MEMORY_HOTPLUG */ 78 #define __meminit __section(.meminit.text) __cold notrace 79 #define __meminitdata __section(.meminit.data) 80 #define __meminitconst __section(.meminit.rodata) 81 #define __memexit __section(.memexit.text) __exitused __cold notrace 82 #define __memexitdata __section(.memexit.data) 83 #define __memexitconst __section(.memexit.rodata) 84 85 /* For assembly routines */ 86 #define __HEAD .section ".head.text","ax" 87 #define __INIT .section ".init.text","ax" 88 #define __FINIT .previous 89 90 #define __INITDATA .section ".init.data","aw",%progbits 91 #define __INITRODATA .section ".init.rodata","a",%progbits 92 #define __FINITDATA .previous 93 94 #define __MEMINIT .section ".meminit.text", "ax" 95 #define __MEMINITDATA .section ".meminit.data", "aw" 96 #define __MEMINITRODATA .section ".meminit.rodata", "a" 97 98 /* silence warnings when references are OK */ 99 #define __REF .section ".ref.text", "ax" 100 #define __REFDATA .section ".ref.data", "aw" 101 #define __REFCONST .section ".ref.rodata", "a" 102 103 #ifndef __ASSEMBLY__ 104 /* 105 * Used for initialization calls.. 106 */ 107 typedef int (*initcall_t)(void); 108 typedef void (*exitcall_t)(void); 109 110 extern initcall_t __con_initcall_start[], __con_initcall_end[]; 111 extern initcall_t __security_initcall_start[], __security_initcall_end[]; 112 113 /* Used for contructor calls. */ 114 typedef void (*ctor_fn_t)(void); 115 116 /* Defined in init/main.c */ 117 extern int do_one_initcall(initcall_t fn); 118 extern char __initdata boot_command_line[]; 119 extern char *saved_command_line; 120 extern unsigned int reset_devices; 121 122 /* used by init/main.c */ 123 void setup_arch(char **); 124 void prepare_namespace(void); 125 void __init load_default_modules(void); 126 int __init init_rootfs(void); 127 128 #ifdef CONFIG_DEBUG_RODATA 129 void mark_rodata_ro(void); 130 #endif 131 132 extern void (*late_time_init)(void); 133 134 extern bool initcall_debug; 135 136 #endif 137 138 #ifndef MODULE 139 140 #ifndef __ASSEMBLY__ 141 142 #ifdef CONFIG_LTO 143 /* Work around a LTO gcc problem: when there is no reference to a variable 144 * in a module it will be moved to the end of the program. This causes 145 * reordering of initcalls which the kernel does not like. 146 * Add a dummy reference function to avoid this. The function is 147 * deleted by the linker. 148 */ 149 #define LTO_REFERENCE_INITCALL(x) \ 150 ; /* yes this is needed */ \ 151 static __used __exit void *reference_##x(void) \ 152 { \ 153 return &x; \ 154 } 155 #else 156 #define LTO_REFERENCE_INITCALL(x) 157 #endif 158 159 /* initcalls are now grouped by functionality into separate 160 * subsections. Ordering inside the subsections is determined 161 * by link order. 162 * For backwards compatibility, initcall() puts the call in 163 * the device init subsection. 164 * 165 * The `id' arg to __define_initcall() is needed so that multiple initcalls 166 * can point at the same handler without causing duplicate-symbol build errors. 167 */ 168 169 #define __define_initcall(fn, id) \ 170 static initcall_t __initcall_##fn##id __used \ 171 __attribute__((__section__(".initcall" #id ".init"))) = fn; \ 172 LTO_REFERENCE_INITCALL(__initcall_##fn##id) 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