include/linux/init.h

   1 #ifndef _LINUX_INIT_H
   2 #define _LINUX_INIT_H
   3
   4 #include <linux/compiler.h>
   5
   6 /* These macros are used to mark some functions or
   7  * initialized data (doesn't apply to uninitialized data)
   8  * as `initialization' functions. The kernel can take this
   9  * as hint that the function is used only during the initialization
  10  * phase and free up used memory resources after
  11  *
  12  * Usage:
  13  * For functions:
  14  *
  15  * You should add __init immediately before the function name, like:
  16  *
  17  * static void __init initme(int x, int y)
  18  * {
  19  *    extern int z; z = x * y;
  20  * }
  21  *
  22  * If the function has a prototype somewhere, you can also add
  23  * __init between closing brace of the prototype and semicolon:
  24  *
  25  * extern int initialize_foobar_device(int, int, int) __init;
  26  *
  27  * For initialized data:
  28  * You should insert __initdata between the variable name and equal
  29  * sign followed by value, e.g.:
  30  *
  31  * static int init_variable __initdata = 0;
  32  * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
  33  *
  34  * Don't forget to initialize data not at file scope, i.e. within a function,
  35  * as gcc otherwise puts the data into the bss section and not into the init
  36  * section.
  37  *
  38  * Also note, that this data cannot be "const".
  39  */
  40
  41 /* These are for everybody (although not all archs will actually
  42    discard it in modules) */
  43 #define __init          __section(.init.text) __cold notrace
  44 #define __initdata      __section(.init.data)
  45 #define __initconst     __section(.init.rodata)
  46 #define __exitdata      __section(.exit.data)
  47 #define __exit_call     __used __section(.exitcall.exit)
  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  * The following markers are used for the cases where the reference to
  56  * the *init / *exit section (code or data) is valid and will teach
  57  * modpost not to issue a warning.
  58  * The markers follow same syntax rules as __init / __initdata. */
  59 #define __ref            __section(.ref.text) noinline
  60 #define __refdata        __section(.ref.data)
  61 #define __refconst       __section(.ref.rodata)
  62
  63 /* compatibility defines */
  64 #define __init_refok     __ref
  65 #define __initdata_refok __refdata
  66 #define __exit_refok     __ref
  67
  68
  69 #ifdef MODULE
  70 #define __exitused
  71 #else
  72 #define __exitused  __used
  73 #endif
  74
  75 #define __exit          __section(.exit.text) __exitused __cold
  76
  77 /* Used for HOTPLUG */
  78 #define __devinit        __section(.devinit.text) __cold
  79 #define __devinitdata    __section(.devinit.data)
  80 #define __devinitconst   __section(.devinit.rodata)
  81 #define __devexit        __section(.devexit.text) __exitused __cold
  82 #define __devexitdata    __section(.devexit.data)
  83 #define __devexitconst   __section(.devexit.rodata)
  84
  85 /* Used for HOTPLUG_CPU */
  86 #define __cpuinit        __section(.cpuinit.text) __cold
  87 #define __cpuinitdata    __section(.cpuinit.data)
  88 #define __cpuinitconst   __section(.cpuinit.rodata)
  89 #define __cpuexit        __section(.cpuexit.text) __exitused __cold
  90 #define __cpuexitdata    __section(.cpuexit.data)
  91 #define __cpuexitconst   __section(.cpuexit.rodata)
  92
  93 /* Used for MEMORY_HOTPLUG */
  94 #define __meminit        __section(.meminit.text) __cold
  95 #define __meminitdata    __section(.meminit.data)
  96 #define __meminitconst   __section(.meminit.rodata)
  97 #define __memexit        __section(.memexit.text) __exitused __cold
  98 #define __memexitdata    __section(.memexit.data)
  99 #define __memexitconst   __section(.memexit.rodata)
 100
 101 /* For assembly routines */
 102 #define __HEAD          .section        ".head.text","ax"
 103 #define __INIT          .section        ".init.text","ax"
 104 #define __FINIT         .previous
 105
 106 #define __INITDATA      .section        ".init.data","aw",%progbits
 107 #define __INITRODATA    .section        ".init.rodata","a",%progbits
 108 #define __FINITDATA     .previous
 109
 110 #define __DEVINIT        .section       ".devinit.text", "ax"
 111 #define __DEVINITDATA    .section       ".devinit.data", "aw"
 112 #define __DEVINITRODATA  .section       ".devinit.rodata", "a"
 113
 114 #define __CPUINIT        .section       ".cpuinit.text", "ax"
 115 #define __CPUINITDATA    .section       ".cpuinit.data", "aw"
 116 #define __CPUINITRODATA  .section       ".cpuinit.rodata", "a"
 117
 118 #define __MEMINIT        .section       ".meminit.text", "ax"
 119 #define __MEMINITDATA    .section       ".meminit.data", "aw"
 120 #define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 121
 122 /* silence warnings when references are OK */
 123 #define __REF            .section       ".ref.text", "ax"
 124 #define __REFDATA        .section       ".ref.data", "aw"
 125 #define __REFCONST       .section       ".ref.rodata", "a"
 126
 127 #ifndef __ASSEMBLY__
 128 /*
 129  * Used for initialization calls..
 130  */
 131 typedef int (*initcall_t)(void);
 132 typedef void (*exitcall_t)(void);
 133
 134 extern initcall_t __con_initcall_start[], __con_initcall_end[];
 135 extern initcall_t __security_initcall_start[], __security_initcall_end[];
 136
 137 /* Used for contructor calls. */
 138 typedef void (*ctor_fn_t)(void);
 139
 140 /* Defined in init/main.c */
 141 extern int do_one_initcall(initcall_t fn);
 142 extern char __initdata boot_command_line[];
 143 extern char *saved_command_line;
 144 extern unsigned int reset_devices;
 145
 146 /* used by init/main.c */
 147 void setup_arch(char **);
 148 void prepare_namespace(void);
 149
 150 extern void (*late_time_init)(void);
 151
 152 #endif
 153
 154 #ifndef MODULE
 155
 156 #ifndef __ASSEMBLY__
 157
 158 /* initcalls are now grouped by functionality into separate
 159  * subsections. Ordering inside the subsections is determined
 160  * by link order.
 161  * For backwards compatibility, initcall() puts the call in
 162  * the device init subsection.
 163  *
 164  * The `id' arg to __define_initcall() is needed so that multiple initcalls
 165  * can point at the same handler without causing duplicate-symbol build errors.
 166  */
 167
 168 #define __define_initcall(level,fn,id) \
 169         static initcall_t __initcall_##fn##id __used \
 170         __attribute__((__section__(".initcall" level ".init"))) = fn
 171
 172 /*
 173  * Early initcalls run before initializing SMP.
 174  *
 175  * Only for built-in code, not modules.
 176  */
 177 #define early_initcall(fn)              __define_initcall("early",fn,early)
 178
 179 /*
 180  * A "pure" initcall has no dependencies on anything else, and purely
 181  * initializes variables that couldn't be statically initialized.
 182  *
 183  * This only exists for built-in code, not for modules.
 184  */
 185 #define pure_initcall(fn)               __define_initcall("0",fn,0)
 186
 187 #define core_initcall(fn)               __define_initcall("1",fn,1)
 188 #define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
 189 #define postcore_initcall(fn)           __define_initcall("2",fn,2)
 190 #define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
 191 #define arch_initcall(fn)               __define_initcall("3",fn,3)
 192 #define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
 193 #define subsys_initcall(fn)             __define_initcall("4",fn,4)
 194 #define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
 195 #define fs_initcall(fn)                 __define_initcall("5",fn,5)
 196 #define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
 197 #define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
 198 #define device_initcall(fn)             __define_initcall("6",fn,6)
 199 #define device_initcall_sync(fn)        __define_initcall("6s",fn,6s)
 200 #define late_initcall(fn)               __define_initcall("7",fn,7)
 201 #define late_initcall_sync(fn)          __define_initcall("7s",fn,7s)
 202
 203 #define __initcall(fn) device_initcall(fn)
 204
 205 #define __exitcall(fn) \
 206         static exitcall_t __exitcall_##fn __exit_call = fn
 207
 208 #define console_initcall(fn) \
 209         static initcall_t __initcall_##fn \
 210         __used __section(.con_initcall.init) = fn
 211
 212 #define security_initcall(fn) \
 213         static initcall_t __initcall_##fn \
 214         __used __section(.security_initcall.init) = fn
 215
 216 struct obs_kernel_param {
 217         const char *str;
 218         int (*setup_func)(char *);
 219         int early;
 220 };
 221
 222 /*
 223  * Only for really core code.  See moduleparam.h for the normal way.
 224  *
 225  * Force the alignment so the compiler doesn't space elements of the
 226  * obs_kernel_param "array" too far apart in .init.setup.
 227  */
 228 #define __setup_param(str, unique_id, fn, early)                        \
 229         static const char __setup_str_##unique_id[] __initconst \
 230                 __aligned(1) = str; \
 231         static struct obs_kernel_param __setup_##unique_id      \
 232                 __used __section(.init.setup)                   \
 233                 __attribute__((aligned((sizeof(long)))))        \
 234                 = { __setup_str_##unique_id, fn, early }
 235
 236 #define __setup(str, fn)                                        \
 237         __setup_param(str, fn, fn, 0)
 238
 239 /* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 240  * returns non-zero. */
 241 #define early_param(str, fn)                                    \
 242         __setup_param(str, fn, fn, 1)
 243
 244 /* Relies on boot_command_line being set */
 245 void __init parse_early_param(void);
 246 void __init parse_early_options(char *cmdline);
 247 #endif /* __ASSEMBLY__ */
 248
 249 /**
 250  * module_init() - driver initialization entry point
 251  * @x: function to be run at kernel boot time or module insertion
 252  *
 253  * module_init() will either be called during do_initcalls() (if
 254  * builtin) or at module insertion time (if a module).  There can only
 255  * be one per module.
 256  */
 257 #define module_init(x)  __initcall(x);
 258
 259 /**
 260  * module_exit() - driver exit entry point
 261  * @x: function to be run when driver is removed
 262  *
 263  * module_exit() will wrap the driver clean-up code
 264  * with cleanup_module() when used with rmmod when
 265  * the driver is a module.  If the driver is statically
 266  * compiled into the kernel, module_exit() has no effect.
 267  * There can only be one per module.
 268  */
 269 #define module_exit(x)  __exitcall(x);
 270
 271 #else /* MODULE */
 272
 273 /* Don't use these in modules, but some people do... */
 274 #define core_initcall(fn)               module_init(fn)
 275 #define postcore_initcall(fn)           module_init(fn)
 276 #define arch_initcall(fn)               module_init(fn)
 277 #define subsys_initcall(fn)             module_init(fn)
 278 #define fs_initcall(fn)                 module_init(fn)
 279 #define device_initcall(fn)             module_init(fn)
 280 #define late_initcall(fn)               module_init(fn)
 281
 282 #define security_initcall(fn)           module_init(fn)
 283
 284 /* Each module must use one module_init(). */
 285 #define module_init(initfn)                                     \
 286         static inline initcall_t __inittest(void)               \
 287         { return initfn; }                                      \
 288         int init_module(void) __attribute__((alias(#initfn)));
 289
 290 /* This is only required if you want to be unloadable. */
 291 #define module_exit(exitfn)                                     \
 292         static inline exitcall_t __exittest(void)               \
 293         { return exitfn; }                                      \
 294         void cleanup_module(void) __attribute__((alias(#exitfn)));
 295
 296 #define __setup_param(str, unique_id, fn)       /* nothing */
 297 #define __setup(str, func)                      /* nothing */
 298 #endif
 299
 300 /* Data marked not to be saved by software suspend */
 301 #define __nosavedata __section(.data.nosave)
 302
 303 /* This means "can be init if no module support, otherwise module load
 304    may call it." */
 305 #ifdef CONFIG_MODULES
 306 #define __init_or_module
 307 #define __initdata_or_module
 308 #define __initconst_or_module
 309 #define __INIT_OR_MODULE        .text
 310 #define __INITDATA_OR_MODULE    .data
 311 #define __INITRODATA_OR_MODULE  .section ".rodata","a",%progbits
 312 #else
 313 #define __init_or_module __init
 314 #define __initdata_or_module __initdata
 315 #define __initconst_or_module __initconst
 316 #define __INIT_OR_MODULE __INIT
 317 #define __INITDATA_OR_MODULE __INITDATA
 318 #define __INITRODATA_OR_MODULE __INITRODATA
 319 #endif /*CONFIG_MODULES*/
 320
 321 /* Functions marked as __devexit may be discarded at kernel link time, depending
 322    on config options.  Newer versions of binutils detect references from
 323    retained sections to discarded sections and flag an error.  Pointers to
 324    __devexit functions must use __devexit_p(function_name), the wrapper will
 325    insert either the function_name or NULL, depending on the config options.
 326  */
 327 #if defined(MODULE) || defined(CONFIG_HOTPLUG)
 328 #define __devexit_p(x) x
 329 #else
 330 #define __devexit_p(x) NULL
 331 #endif
 332
 333 #ifdef MODULE
 334 #define __exit_p(x) x
 335 #else
 336 #define __exit_p(x) NULL
 337 #endif
 338
 339 #endif /* _LINUX_INIT_H */