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 char linux_logo[] __initdata = { 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
  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 /* backward compatibility note
  64  *  A few places hardcode the old section names:
  65  *  .text.init.refok
  66  *  .data.init.refok
  67  *  .exit.text.refok
  68  *  They should be converted to use the defines from this file
  69  */
  70
  71 /* compatibility defines */
  72 #define __init_refok     __ref
  73 #define __initdata_refok __refdata
  74 #define __exit_refok     __ref
  75
  76
  77 #ifdef MODULE
  78 #define __exitused
  79 #else
  80 #define __exitused  __used
  81 #endif
  82
  83 #define __exit          __section(.exit.text) __exitused __cold
  84
  85 /* Used for HOTPLUG */
  86 #define __devinit        __section(.devinit.text) __cold
  87 #define __devinitdata    __section(.devinit.data)
  88 #define __devinitconst   __section(.devinit.rodata)
  89 #define __devexit        __section(.devexit.text) __exitused __cold
  90 #define __devexitdata    __section(.devexit.data)
  91 #define __devexitconst   __section(.devexit.rodata)
  92
  93 /* Used for HOTPLUG_CPU */
  94 #define __cpuinit        __section(.cpuinit.text) __cold
  95 #define __cpuinitdata    __section(.cpuinit.data)
  96 #define __cpuinitconst   __section(.cpuinit.rodata)
  97 #define __cpuexit        __section(.cpuexit.text) __exitused __cold
  98 #define __cpuexitdata    __section(.cpuexit.data)
  99 #define __cpuexitconst   __section(.cpuexit.rodata)
 100
 101 /* Used for MEMORY_HOTPLUG */
 102 #define __meminit        __section(.meminit.text) __cold
 103 #define __meminitdata    __section(.meminit.data)
 104 #define __meminitconst   __section(.meminit.rodata)
 105 #define __memexit        __section(.memexit.text) __exitused __cold
 106 #define __memexitdata    __section(.memexit.data)
 107 #define __memexitconst   __section(.memexit.rodata)
 108
 109 /* For assembly routines */
 110 #define __HEAD          .section        ".head.text","ax"
 111 #define __INIT          .section        ".init.text","ax"
 112 #define __FINIT         .previous
 113
 114 #define __INITDATA      .section        ".init.data","aw"
 115 #define __FINITDATA     .previous
 116
 117 #define __DEVINIT        .section       ".devinit.text", "ax"
 118 #define __DEVINITDATA    .section       ".devinit.data", "aw"
 119
 120 #define __CPUINIT        .section       ".cpuinit.text", "ax"
 121 #define __CPUINITDATA    .section       ".cpuinit.data", "aw"
 122
 123 #define __MEMINIT        .section       ".meminit.text", "ax"
 124 #define __MEMINITDATA    .section       ".meminit.data", "aw"
 125
 126 /* silence warnings when references are OK */
 127 #define __REF            .section       ".ref.text", "ax"
 128 #define __REFDATA        .section       ".ref.data", "aw"
 129 #define __REFCONST       .section       ".ref.rodata", "aw"
 130
 131 #ifndef __ASSEMBLY__
 132 /*
 133  * Used for initialization calls..
 134  */
 135 typedef int (*initcall_t)(void);
 136 typedef void (*exitcall_t)(void);
 137
 138 extern initcall_t __con_initcall_start[], __con_initcall_end[];
 139 extern initcall_t __security_initcall_start[], __security_initcall_end[];
 140
 141 /* Defined in init/main.c */
 142 extern int do_one_initcall(initcall_t fn);
 143 extern char __initdata boot_command_line[];
 144 extern char *saved_command_line;
 145 extern unsigned int reset_devices;
 146
 147 /* used by init/main.c */
 148 void setup_arch(char **);
 149 void prepare_namespace(void);
 150
 151 extern void (*late_time_init)(void);
 152
 153 #endif
 154
 155 #ifndef MODULE
 156
 157 #ifndef __ASSEMBLY__
 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(level,fn,id) \
 170         static initcall_t __initcall_##fn##id __used \
 171         __attribute__((__section__(".initcall" level ".init"))) = fn
 172
 173 /*
 174  * Early initcalls run before initializing SMP.
 175  *
 176  * Only for built-in code, not modules.
 177  */
 178 #define early_initcall(fn)              __define_initcall("early",fn,early)
 179
 180 /*
 181  * A "pure" initcall has no dependencies on anything else, and purely
 182  * initializes variables that couldn't be statically initialized.
 183  *
 184  * This only exists for built-in code, not for modules.
 185  */
 186 #define pure_initcall(fn)               __define_initcall("0",fn,0)
 187
 188 #define core_initcall(fn)               __define_initcall("1",fn,1)
 189 #define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
 190 #define postcore_initcall(fn)           __define_initcall("2",fn,2)
 191 #define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
 192 #define arch_initcall(fn)               __define_initcall("3",fn,3)
 193 #define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
 194 #define subsys_initcall(fn)             __define_initcall("4",fn,4)
 195 #define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
 196 #define fs_initcall(fn)                 __define_initcall("5",fn,5)
 197 #define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
 198 #define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
 199 #define device_initcall(fn)             __define_initcall("6",fn,6)
 200 #define device_initcall_sync(fn)        __define_initcall("6s",fn,6s)
 201 #define late_initcall(fn)               __define_initcall("7",fn,7)
 202 #define late_initcall_sync(fn)          __define_initcall("7s",fn,7s)
 203
 204 #define __initcall(fn) device_initcall(fn)
 205
 206 #define __exitcall(fn) \
 207         static exitcall_t __exitcall_##fn __exit_call = fn
 208
 209 #define console_initcall(fn) \
 210         static initcall_t __initcall_##fn \
 211         __used __section(.con_initcall.init) = fn
 212
 213 #define security_initcall(fn) \
 214         static initcall_t __initcall_##fn \
 215         __used __section(.security_initcall.init) = fn
 216
 217 struct obs_kernel_param {
 218         const char *str;
 219         int (*setup_func)(char *);
 220         int early;
 221 };
 222
 223 /*
 224  * Only for really core code.  See moduleparam.h for the normal way.
 225  *
 226  * Force the alignment so the compiler doesn't space elements of the
 227  * obs_kernel_param "array" too far apart in .init.setup.
 228  */
 229 #define __setup_param(str, unique_id, fn, early)                        \
 230         static char __setup_str_##unique_id[] __initdata __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_null_param(str, unique_id)                      \
 237         __setup_param(str, unique_id, NULL, 0)
 238
 239 #define __setup(str, fn)                                        \
 240         __setup_param(str, fn, fn, 0)
 241
 242 /* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 243  * returns non-zero. */
 244 #define early_param(str, fn)                                    \
 245         __setup_param(str, fn, fn, 1)
 246
 247 /* Relies on boot_command_line being set */
 248 void __init parse_early_param(void);
 249 #endif /* __ASSEMBLY__ */
 250
 251 /**
 252  * module_init() - driver initialization entry point
 253  * @x: function to be run at kernel boot time or module insertion
 254  *
 255  * module_init() will either be called during do_initcalls() (if
 256  * builtin) or at module insertion time (if a module).  There can only
 257  * be one per module.
 258  */
 259 #define module_init(x)  __initcall(x);
 260
 261 /**
 262  * module_exit() - driver exit entry point
 263  * @x: function to be run when driver is removed
 264  *
 265  * module_exit() will wrap the driver clean-up code
 266  * with cleanup_module() when used with rmmod when
 267  * the driver is a module.  If the driver is statically
 268  * compiled into the kernel, module_exit() has no effect.
 269  * There can only be one per module.
 270  */
 271 #define module_exit(x)  __exitcall(x);
 272
 273 #else /* MODULE */
 274
 275 /* Don't use these in modules, but some people do... */
 276 #define core_initcall(fn)               module_init(fn)
 277 #define postcore_initcall(fn)           module_init(fn)
 278 #define arch_initcall(fn)               module_init(fn)
 279 #define subsys_initcall(fn)             module_init(fn)
 280 #define fs_initcall(fn)                 module_init(fn)
 281 #define device_initcall(fn)             module_init(fn)
 282 #define late_initcall(fn)               module_init(fn)
 283
 284 #define security_initcall(fn)           module_init(fn)
 285
 286 /* Each module must use one module_init(). */
 287 #define module_init(initfn)                                     \
 288         static inline initcall_t __inittest(void)               \
 289         { return initfn; }                                      \
 290         int init_module(void) __attribute__((alias(#initfn)));
 291
 292 /* This is only required if you want to be unloadable. */
 293 #define module_exit(exitfn)                                     \
 294         static inline exitcall_t __exittest(void)               \
 295         { return exitfn; }                                      \
 296         void cleanup_module(void) __attribute__((alias(#exitfn)));
 297
 298 #define __setup_param(str, unique_id, fn)       /* nothing */
 299 #define __setup_null_param(str, unique_id)      /* nothing */
 300 #define __setup(str, func)                      /* nothing */
 301 #endif
 302
 303 /* Data marked not to be saved by software suspend */
 304 #define __nosavedata __section(.data.nosave)
 305
 306 /* This means "can be init if no module support, otherwise module load
 307    may call it." */
 308 #ifdef CONFIG_MODULES
 309 #define __init_or_module
 310 #define __initdata_or_module
 311 #else
 312 #define __init_or_module __init
 313 #define __initdata_or_module __initdata
 314 #endif /*CONFIG_MODULES*/
 315
 316 /* Functions marked as __devexit may be discarded at kernel link time, depending
 317    on config options.  Newer versions of binutils detect references from
 318    retained sections to discarded sections and flag an error.  Pointers to
 319    __devexit functions must use __devexit_p(function_name), the wrapper will
 320    insert either the function_name or NULL, depending on the config options.
 321  */
 322 #if defined(MODULE) || defined(CONFIG_HOTPLUG)
 323 #define __devexit_p(x) x
 324 #else
 325 #define __devexit_p(x) NULL
 326 #endif
 327
 328 #ifdef MODULE
 329 #define __exit_p(x) x
 330 #else
 331 #define __exit_p(x) NULL
 332 #endif
 333
 334 #endif /* _LINUX_INIT_H */