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