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 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 /* 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 __INITRODATA    .section        ".init.rodata","a"
 116 #define __FINITDATA     .previous
 117
 118 #define __DEVINIT        .section       ".devinit.text", "ax"
 119 #define __DEVINITDATA    .section       ".devinit.data", "aw"
 120 #define __DEVINITRODATA  .section       ".devinit.rodata", "a"
 121
 122 #define __CPUINIT        .section       ".cpuinit.text", "ax"
 123 #define __CPUINITDATA    .section       ".cpuinit.data", "aw"
 124 #define __CPUINITRODATA  .section       ".cpuinit.rodata", "a"
 125
 126 #define __MEMINIT        .section       ".meminit.text", "ax"
 127 #define __MEMINITDATA    .section       ".meminit.data", "aw"
 128 #define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 129
 130 /* silence warnings when references are OK */
 131 #define __REF            .section       ".ref.text", "ax"
 132 #define __REFDATA        .section       ".ref.data", "aw"
 133 #define __REFCONST       .section       ".ref.rodata", "a"
 134
 135 #ifndef __ASSEMBLY__
 136 /*
 137  * Used for initialization calls..
 138  */
 139 typedef int (*initcall_t)(void);
 140 typedef void (*exitcall_t)(void);
 141
 142 extern initcall_t __con_initcall_start[], __con_initcall_end[];
 143 extern initcall_t __security_initcall_start[], __security_initcall_end[];
 144
 145 /* Defined in init/main.c */
 146 extern int do_one_initcall(initcall_t fn);
 147 extern char __initdata boot_command_line[];
 148 extern char *saved_command_line;
 149 extern unsigned int reset_devices;
 150
 151 /* used by init/main.c */
 152 void setup_arch(char **);
 153 void prepare_namespace(void);
 154
 155 extern void (*late_time_init)(void);
 156
 157 #endif
 158
 159 #ifndef MODULE
 160
 161 #ifndef __ASSEMBLY__
 162
 163 /* initcalls are now grouped by functionality into separate
 164  * subsections. Ordering inside the subsections is determined
 165  * by link order.
 166  * For backwards compatibility, initcall() puts the call in
 167  * the device init subsection.
 168  *
 169  * The `id' arg to __define_initcall() is needed so that multiple initcalls
 170  * can point at the same handler without causing duplicate-symbol build errors.
 171  */
 172
 173 #define __define_initcall(level,fn,id) \
 174         static initcall_t __initcall_##fn##id __used \
 175         __attribute__((__section__(".initcall" level ".init"))) = fn
 176
 177 /*
 178  * Early initcalls run before initializing SMP.
 179  *
 180  * Only for built-in code, not modules.
 181  */
 182 #define early_initcall(fn)              __define_initcall("early",fn,early)
 183
 184 /*
 185  * A "pure" initcall has no dependencies on anything else, and purely
 186  * initializes variables that couldn't be statically initialized.
 187  *
 188  * This only exists for built-in code, not for modules.
 189  */
 190 #define pure_initcall(fn)               __define_initcall("0",fn,0)
 191
 192 #define core_initcall(fn)               __define_initcall("1",fn,1)
 193 #define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
 194 #define postcore_initcall(fn)           __define_initcall("2",fn,2)
 195 #define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
 196 #define arch_initcall(fn)               __define_initcall("3",fn,3)
 197 #define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
 198 #define subsys_initcall(fn)             __define_initcall("4",fn,4)
 199 #define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
 200 #define fs_initcall(fn)                 __define_initcall("5",fn,5)
 201 #define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
 202 #define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
 203 #define device_initcall(fn)             __define_initcall("6",fn,6)
 204 #define device_initcall_sync(fn)        __define_initcall("6s",fn,6s)
 205 #define late_initcall(fn)               __define_initcall("7",fn,7)
 206 #define late_initcall_sync(fn)          __define_initcall("7s",fn,7s)
 207
 208 #define __initcall(fn) device_initcall(fn)
 209
 210 #define __exitcall(fn) \
 211         static exitcall_t __exitcall_##fn __exit_call = fn
 212
 213 #define console_initcall(fn) \
 214         static initcall_t __initcall_##fn \
 215         __used __section(.con_initcall.init) = fn
 216
 217 #define security_initcall(fn) \
 218         static initcall_t __initcall_##fn \
 219         __used __section(.security_initcall.init) = fn
 220
 221 struct obs_kernel_param {
 222         const char *str;
 223         int (*setup_func)(char *);
 224         int early;
 225 };
 226
 227 /*
 228  * Only for really core code.  See moduleparam.h for the normal way.
 229  *
 230  * Force the alignment so the compiler doesn't space elements of the
 231  * obs_kernel_param "array" too far apart in .init.setup.
 232  */
 233 #define __setup_param(str, unique_id, fn, early)                        \
 234         static char __setup_str_##unique_id[] __initdata __aligned(1) = str; \
 235         static struct obs_kernel_param __setup_##unique_id      \
 236                 __used __section(.init.setup)                   \
 237                 __attribute__((aligned((sizeof(long)))))        \
 238                 = { __setup_str_##unique_id, fn, early }
 239
 240 #define __setup(str, fn)                                        \
 241         __setup_param(str, fn, fn, 0)
 242
 243 /* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 244  * returns non-zero. */
 245 #define early_param(str, fn)                                    \
 246         __setup_param(str, fn, fn, 1)
 247
 248 /* Relies on boot_command_line being set */
 249 void __init parse_early_param(void);
 250 #endif /* __ASSEMBLY__ */
 251
 252 /**
 253  * module_init() - driver initialization entry point
 254  * @x: function to be run at kernel boot time or module insertion
 255  *
 256  * module_init() will either be called during do_initcalls() (if
 257  * builtin) or at module insertion time (if a module).  There can only
 258  * be one per module.
 259  */
 260 #define module_init(x)  __initcall(x);
 261
 262 /**
 263  * module_exit() - driver exit entry point
 264  * @x: function to be run when driver is removed
 265  *
 266  * module_exit() will wrap the driver clean-up code
 267  * with cleanup_module() when used with rmmod when
 268  * the driver is a module.  If the driver is statically
 269  * compiled into the kernel, module_exit() has no effect.
 270  * There can only be one per module.
 271  */
 272 #define module_exit(x)  __exitcall(x);
 273
 274 #else /* MODULE */
 275
 276 /* Don't use these in modules, but some people do... */
 277 #define core_initcall(fn)               module_init(fn)
 278 #define postcore_initcall(fn)           module_init(fn)
 279 #define arch_initcall(fn)               module_init(fn)
 280 #define subsys_initcall(fn)             module_init(fn)
 281 #define fs_initcall(fn)                 module_init(fn)
 282 #define device_initcall(fn)             module_init(fn)
 283 #define late_initcall(fn)               module_init(fn)
 284
 285 #define security_initcall(fn)           module_init(fn)
 286
 287 /* Each module must use one module_init(). */
 288 #define module_init(initfn)                                     \
 289         static inline initcall_t __inittest(void)               \
 290         { return initfn; }                                      \
 291         int init_module(void) __attribute__((alias(#initfn)));
 292
 293 /* This is only required if you want to be unloadable. */
 294 #define module_exit(exitfn)                                     \
 295         static inline exitcall_t __exittest(void)               \
 296         { return exitfn; }                                      \
 297         void cleanup_module(void) __attribute__((alias(#exitfn)));
 298
 299 #define __setup_param(str, unique_id, fn)       /* 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 /*
 317  * Functions marked as __devexit may be discarded at kernel link time,
 318  * depending on config options.  Newer versions of binutils detect
 319  * references from retained sections to discarded sections and flag an
 320  * error.
 321  *
 322  * Pointers to __devexit functions must use __devexit_p(function_name),
 323  * the wrapper will insert either the function_name or NULL, depending on
 324  * the config options.
 325  */
 326 #if defined(MODULE) || defined(CONFIG_HOTPLUG)
 327 # define __devexit_p(x) x
 328 #else
 329 # define __devexit_p(x) ((void *)((long)(x) & 0) /* NULL */)
 330 #endif
 331
 332 #ifdef MODULE
 333 #define __exit_p(x) x
 334 #else
 335 #define __exit_p(x) NULL
 336 #endif
 337
 338 #endif /* _LINUX_INIT_H */