include/linux/init.h

   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 between the variable name and equal
  30  * 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  * Also note, that this data cannot be "const".
  40  */
  41
  42 /* These are for everybody (although not all archs will actually
  43    discard it in modules) */
  44 #define __init          __section(.init.text) __cold notrace
  45 #define __initdata      __section(.init.data)
  46 #define __initconst     __constsection(.init.rodata)
  47 #define __exitdata      __section(.exit.data)
  48 #define __exit_call     __used __section(.exitcall.exit)
  49
  50 /*
  51  * Some architecture have tool chains which do not handle rodata attributes
  52  * correctly. For those disable special sections for const, so that other
  53  * architectures can annotate correctly.
  54  */
  55 #ifdef CONFIG_BROKEN_RODATA
  56 #define __constsection(x)
  57 #else
  58 #define __constsection(x) __section(x)
  59 #endif
  60
  61 /*
  62  * modpost check for section mismatches during the kernel build.
  63  * A section mismatch happens when there are references from a
  64  * code or data section to an init section (both code or data).
  65  * The init sections are (for most archs) discarded by the kernel
  66  * when early init has completed so all such references are potential bugs.
  67  * For exit sections the same issue exists.
  68  *
  69  * The following markers are used for the cases where the reference to
  70  * the *init / *exit section (code or data) is valid and will teach
  71  * modpost not to issue a warning.  Intended semantics is that a code or
  72  * data tagged __ref* can reference code or data from init section without
  73  * producing a warning (of course, no warning does not mean code is
  74  * correct, so optimally document why the __ref is needed and why it's OK).
  75  *
  76  * The markers follow same syntax rules as __init / __initdata.
  77  */
  78 #define __ref            __section(.ref.text) noinline
  79 #define __refdata        __section(.ref.data)
  80 #define __refconst       __constsection(.ref.rodata)
  81
  82 /* compatibility defines */
  83 #define __init_refok     __ref
  84 #define __initdata_refok __refdata
  85 #define __exit_refok     __ref
  86
  87
  88 #ifdef MODULE
  89 #define __exitused
  90 #else
  91 #define __exitused  __used
  92 #endif
  93
  94 #define __exit          __section(.exit.text) __exitused __cold notrace
  95
  96 /* Used for HOTPLUG */
  97 #define __devinit        __section(.devinit.text) __cold notrace
  98 #define __devinitdata    __section(.devinit.data)
  99 #define __devinitconst   __section(.devinit.rodata)
 100 #define __devexit        __section(.devexit.text) __exitused __cold notrace
 101 #define __devexitdata    __section(.devexit.data)
 102 #define __devexitconst   __section(.devexit.rodata)
 103
 104 /* Used for HOTPLUG_CPU */
 105 #define __cpuinit        __section(.cpuinit.text) __cold notrace
 106 #define __cpuinitdata    __section(.cpuinit.data)
 107 #define __cpuinitconst   __constsection(.cpuinit.rodata)
 108 #define __cpuexit        __section(.cpuexit.text) __exitused __cold notrace
 109 #define __cpuexitdata    __section(.cpuexit.data)
 110 #define __cpuexitconst   __constsection(.cpuexit.rodata)
 111
 112 /* Used for MEMORY_HOTPLUG */
 113 #define __meminit        __section(.meminit.text) __cold notrace
 114 #define __meminitdata    __section(.meminit.data)
 115 #define __meminitconst   __constsection(.meminit.rodata)
 116 #define __memexit        __section(.memexit.text) __exitused __cold notrace
 117 #define __memexitdata    __section(.memexit.data)
 118 #define __memexitconst   __constsection(.memexit.rodata)
 119
 120 /* For assembly routines */
 121 #define __HEAD          .section        ".head.text","ax"
 122 #define __INIT          .section        ".init.text","ax"
 123 #define __FINIT         .previous
 124
 125 #define __INITDATA      .section        ".init.data","aw",%progbits
 126 #define __INITRODATA    .section        ".init.rodata","a",%progbits
 127 #define __FINITDATA     .previous
 128
 129 #define __DEVINIT        .section       ".devinit.text", "ax"
 130 #define __DEVINITDATA    .section       ".devinit.data", "aw"
 131 #define __DEVINITRODATA  .section       ".devinit.rodata", "a"
 132
 133 #define __CPUINIT        .section       ".cpuinit.text", "ax"
 134 #define __CPUINITDATA    .section       ".cpuinit.data", "aw"
 135 #define __CPUINITRODATA  .section       ".cpuinit.rodata", "a"
 136
 137 #define __MEMINIT        .section       ".meminit.text", "ax"
 138 #define __MEMINITDATA    .section       ".meminit.data", "aw"
 139 #define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 140
 141 /* silence warnings when references are OK */
 142 #define __REF            .section       ".ref.text", "ax"
 143 #define __REFDATA        .section       ".ref.data", "aw"
 144 #define __REFCONST       .section       ".ref.rodata", "a"
 145
 146 #ifndef __ASSEMBLY__
 147 /*
 148  * Used for initialization calls..
 149  */
 150 typedef int (*initcall_t)(void);
 151 typedef void (*exitcall_t)(void);
 152
 153 extern initcall_t __con_initcall_start[], __con_initcall_end[];
 154 extern initcall_t __security_initcall_start[], __security_initcall_end[];
 155
 156 /* Used for contructor calls. */
 157 typedef void (*ctor_fn_t)(void);
 158
 159 /* Defined in init/main.c */
 160 extern int do_one_initcall(initcall_t fn);
 161 extern char __initdata boot_command_line[];
 162 extern char *saved_command_line;
 163 extern unsigned int reset_devices;
 164
 165 /* used by init/main.c */
 166 void setup_arch(char **);
 167 void prepare_namespace(void);
 168 void __init load_default_modules(void);
 169
 170 extern void (*late_time_init)(void);
 171
 172 extern bool initcall_debug;
 173
 174 #endif
 175
 176 #ifndef MODULE
 177
 178 #ifndef __ASSEMBLY__
 179
 180 /* initcalls are now grouped by functionality into separate
 181  * subsections. Ordering inside the subsections is determined
 182  * by link order.
 183  * For backwards compatibility, initcall() puts the call in
 184  * the device init subsection.
 185  *
 186  * The `id' arg to __define_initcall() is needed so that multiple initcalls
 187  * can point at the same handler without causing duplicate-symbol build errors.
 188  */
 189
 190 #define __define_initcall(fn, id) \
 191         static initcall_t __initcall_##fn##id __used \
 192         __attribute__((__section__(".initcall" #id ".init"))) = fn
 193
 194 /*
 195  * Early initcalls run before initializing SMP.
 196  *
 197  * Only for built-in code, not modules.
 198  */
 199 #define early_initcall(fn)              __define_initcall(fn, early)
 200
 201 /*
 202  * A "pure" initcall has no dependencies on anything else, and purely
 203  * initializes variables that couldn't be statically initialized.
 204  *
 205  * This only exists for built-in code, not for modules.
 206  * Keep main.c:initcall_level_names[] in sync.
 207  */
 208 #define pure_initcall(fn)               __define_initcall(fn, 0)
 209
 210 #define core_initcall(fn)               __define_initcall(fn, 1)
 211 #define core_initcall_sync(fn)          __define_initcall(fn, 1s)
 212 #define postcore_initcall(fn)           __define_initcall(fn, 2)
 213 #define postcore_initcall_sync(fn)      __define_initcall(fn, 2s)
 214 #define arch_initcall(fn)               __define_initcall(fn, 3)
 215 #define arch_initcall_sync(fn)          __define_initcall(fn, 3s)
 216 #define subsys_initcall(fn)             __define_initcall(fn, 4)
 217 #define subsys_initcall_sync(fn)        __define_initcall(fn, 4s)
 218 #define fs_initcall(fn)                 __define_initcall(fn, 5)
 219 #define fs_initcall_sync(fn)            __define_initcall(fn, 5s)
 220 #define rootfs_initcall(fn)             __define_initcall(fn, rootfs)
 221 #define device_initcall(fn)             __define_initcall(fn, 6)
 222 #define device_initcall_sync(fn)        __define_initcall(fn, 6s)
 223 #define late_initcall(fn)               __define_initcall(fn, 7)
 224 #define late_initcall_sync(fn)          __define_initcall(fn, 7s)
 225
 226 #define __initcall(fn) device_initcall(fn)
 227
 228 #define __exitcall(fn) \
 229         static exitcall_t __exitcall_##fn __exit_call = fn
 230
 231 #define console_initcall(fn) \
 232         static initcall_t __initcall_##fn \
 233         __used __section(.con_initcall.init) = fn
 234
 235 #define security_initcall(fn) \
 236         static initcall_t __initcall_##fn \
 237         __used __section(.security_initcall.init) = fn
 238
 239 #ifdef CONFIG_DEFERRED_INITCALLS
 240 #define deferred_initcall(fn, id) \
 241         static initcall_t __initcall_##fn##id __used \
 242         __attribute__((__section__(".deferred_initcall" #id ".init"))) = fn
 243 #endif
 244
 245 struct obs_kernel_param {
 246         const char *str;
 247         int (*setup_func)(char *);
 248         int early;
 249 };
 250
 251 /*
 252  * Only for really core code.  See moduleparam.h for the normal way.
 253  *
 254  * Force the alignment so the compiler doesn't space elements of the
 255  * obs_kernel_param "array" too far apart in .init.setup.
 256  */
 257 #define __setup_param(str, unique_id, fn, early)                        \
 258         static const char __setup_str_##unique_id[] __initconst \
 259                 __aligned(1) = str; \
 260         static struct obs_kernel_param __setup_##unique_id      \
 261                 __used __section(.init.setup)                   \
 262                 __attribute__((aligned((sizeof(long)))))        \
 263                 = { __setup_str_##unique_id, fn, early }
 264
 265 #define __setup(str, fn)                                        \
 266         __setup_param(str, fn, fn, 0)
 267
 268 /* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 269  * returns non-zero. */
 270 #define early_param(str, fn)                                    \
 271         __setup_param(str, fn, fn, 1)
 272
 273 /* Relies on boot_command_line being set */
 274 void __init parse_early_param(void);
 275 void __init parse_early_options(char *cmdline);
 276 #endif /* __ASSEMBLY__ */
 277
 278 /**
 279  * module_init() - driver initialization entry point
 280  * @x: function to be run at kernel boot time or module insertion
 281  *
 282  * module_init() will either be called during do_initcalls() (if
 283  * builtin) or at module insertion time (if a module).  There can only
 284  * be one per module.
 285  */
 286 #define module_init(x)  __initcall(x);
 287 #ifdef CONFIG_DEFERRED_INITCALLS
 288 #define deferred_module_init(fn) deferred_initcall(fn, 0);
 289 #define deferred_module_init_sync(fn) deferred_initcall(fn, 0s);
 290 #endif
 291
 292 /**
 293  * module_exit() - driver exit entry point
 294  * @x: function to be run when driver is removed
 295  *
 296  * module_exit() will wrap the driver clean-up code
 297  * with cleanup_module() when used with rmmod when
 298  * the driver is a module.  If the driver is statically
 299  * compiled into the kernel, module_exit() has no effect.
 300  * There can only be one per module.
 301  */
 302 #define module_exit(x)  __exitcall(x);
 303
 304 #else /* MODULE */
 305
 306 /* Don't use these in loadable modules, but some people do... */
 307 #define early_initcall(fn)              module_init(fn)
 308 #define core_initcall(fn)               module_init(fn)
 309 #define postcore_initcall(fn)           module_init(fn)
 310 #define arch_initcall(fn)               module_init(fn)
 311 #define subsys_initcall(fn)             module_init(fn)
 312 #define fs_initcall(fn)                 module_init(fn)
 313 #define device_initcall(fn)             module_init(fn)
 314 #define late_initcall(fn)               module_init(fn)
 315
 316 #define security_initcall(fn)           module_init(fn)
 317
 318 /* Each module must use one module_init(). */
 319 #define module_init(initfn)                                     \
 320         static inline initcall_t __inittest(void)               \
 321         { return initfn; }                                      \
 322         int init_module(void) __attribute__((alias(#initfn)));
 323
 324 #ifdef CONFIG_DEFERRED_INITCALLS
 325 #define deferred_module_init(fn) module_init(fn)
 326 #endif
 327
 328 /* This is only required if you want to be unloadable. */
 329 #define module_exit(exitfn)                                     \
 330         static inline exitcall_t __exittest(void)               \
 331         { return exitfn; }                                      \
 332         void cleanup_module(void) __attribute__((alias(#exitfn)));
 333
 334 #define __setup_param(str, unique_id, fn)       /* nothing */
 335 #define __setup(str, func)                      /* nothing */
 336 #endif
 337
 338 /* Data marked not to be saved by software suspend */
 339 #define __nosavedata __section(.data..nosave)
 340
 341 /* This means "can be init if no module support, otherwise module load
 342    may call it." */
 343 #ifdef CONFIG_MODULES
 344 #define __init_or_module
 345 #define __initdata_or_module
 346 #define __initconst_or_module
 347 #define __INIT_OR_MODULE        .text
 348 #define __INITDATA_OR_MODULE    .data
 349 #define __INITRODATA_OR_MODULE  .section ".rodata","a",%progbits
 350 #else
 351 #define __init_or_module __init
 352 #define __initdata_or_module __initdata
 353 #define __initconst_or_module __initconst
 354 #define __INIT_OR_MODULE __INIT
 355 #define __INITDATA_OR_MODULE __INITDATA
 356 #define __INITRODATA_OR_MODULE __INITRODATA
 357 #endif /*CONFIG_MODULES*/
 358
 359 /* Functions marked as __devexit may be discarded at kernel link time, depending
 360    on config options.  Newer versions of binutils detect references from
 361    retained sections to discarded sections and flag an error.  Pointers to
 362    __devexit functions must use __devexit_p(function_name), the wrapper will
 363    insert either the function_name or NULL, depending on the config options.
 364  */
 365 #if defined(MODULE) || defined(CONFIG_HOTPLUG)
 366 #define __devexit_p(x) x
 367 #else
 368 #define __devexit_p(x) NULL
 369 #endif
 370
 371 #ifdef MODULE
 372 #define __exit_p(x) x
 373 #else
 374 #define __exit_p(x) NULL
 375 #endif
 376
 377 #endif /* _LINUX_INIT_H */