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 __exitdata      __section(.exit.data)
  46 #define __exit_call     __used __section(.exitcall.exit)
  47
  48 /* modpost check for section mismatches during the kernel build.
  49  * A section mismatch happens when there are references from a
  50  * code or data section to an init section (both code or data).
  51  * The init sections are (for most archs) discarded by the kernel
  52  * when early init has completed so all such references are potential bugs.
  53  * For exit sections the same issue exists.
  54  * The following markers are used for the cases where the reference to
  55  * the *init / *exit section (code or data) is valid and will teach
  56  * modpost not to issue a warning.
  57  * The markers follow same syntax rules as __init / __initdata. */
  58 #define __ref            __section(.ref.text) noinline
  59 #define __refdata        __section(.ref.data)
  60 #define __refconst       __section(.ref.rodata)
  61
  62 /* backward compatibility note
  63  *  A few places hardcode the old section names:
  64  *  .text.init.refok
  65  *  .data.init.refok
  66  *  .exit.text.refok
  67  *  They should be converted to use the defines from this file
  68  */
  69
  70 /* compatibility defines */
  71 #define __init_refok     __ref
  72 #define __initdata_refok __refdata
  73 #define __exit_refok     __ref
  74
  75
  76 #ifdef MODULE
  77 #define __exitused
  78 #else
  79 #define __exitused  __used
  80 #endif
  81
  82 #define __exit          __section(.exit.text) __exitused __cold
  83
  84 /* Used for HOTPLUG */
  85 #define __devinit        __section(.devinit.text) __cold
  86 #define __devinitdata    __section(.devinit.data)
  87 #define __devinitconst   __section(.devinit.rodata)
  88 #define __devexit        __section(.devexit.text) __exitused __cold
  89 #define __devexitdata    __section(.devexit.data)
  90 #define __devexitconst   __section(.devexit.rodata)
  91
  92 /* Used for HOTPLUG_CPU */
  93 #define __cpuinit        __section(.cpuinit.text) __cold
  94 #define __cpuinitdata    __section(.cpuinit.data)
  95 #define __cpuinitconst   __section(.cpuinit.rodata)
  96 #define __cpuexit        __section(.cpuexit.text) __exitused __cold
  97 #define __cpuexitdata    __section(.cpuexit.data)
  98 #define __cpuexitconst   __section(.cpuexit.rodata)
  99
 100 /* Used for MEMORY_HOTPLUG */
 101 #define __meminit        __section(.meminit.text) __cold
 102 #define __meminitdata    __section(.meminit.data)
 103 #define __meminitconst   __section(.meminit.rodata)
 104 #define __memexit        __section(.memexit.text) __exitused __cold
 105 #define __memexitdata    __section(.memexit.data)
 106 #define __memexitconst   __section(.memexit.rodata)
 107
 108 /* For assembly routines */
 109 #define __INIT          .section        ".init.text","ax"
 110 #define __FINIT         .previous
 111
 112 #define __INITDATA      .section        ".init.data","aw"
 113 #define __FINITDATA     .previous
 114
 115 #define __DEVINIT        .section       ".devinit.text", "ax"
 116 #define __DEVINITDATA    .section       ".devinit.data", "aw"
 117
 118 #define __CPUINIT        .section       ".cpuinit.text", "ax"
 119 #define __CPUINITDATA    .section       ".cpuinit.data", "aw"
 120
 121 #define __MEMINIT        .section       ".meminit.text", "ax"
 122 #define __MEMINITDATA    .section       ".meminit.data", "aw"
 123
 124 /* silence warnings when references are OK */
 125 #define __REF            .section       ".ref.text", "ax"
 126 #define __REFDATA        .section       ".ref.data", "aw"
 127 #define __REFCONST       .section       ".ref.rodata", "aw"
 128
 129 #ifndef __ASSEMBLY__
 130 /*
 131  * Used for initialization calls..
 132  */
 133 typedef int (*initcall_t)(void);
 134 typedef void (*exitcall_t)(void);
 135
 136 extern initcall_t __con_initcall_start[], __con_initcall_end[];
 137 extern initcall_t __security_initcall_start[], __security_initcall_end[];
 138
 139 /* Defined in init/main.c */
 140 extern char __initdata boot_command_line[];
 141 extern char *saved_command_line;
 142 extern unsigned int reset_devices;
 143
 144 /* used by init/main.c */
 145 void setup_arch(char **);
 146 void prepare_namespace(void);
 147
 148 #endif
 149
 150 #ifndef MODULE
 151
 152 #ifndef __ASSEMBLY__
 153
 154 /* initcalls are now grouped by functionality into separate
 155  * subsections. Ordering inside the subsections is determined
 156  * by link order.
 157  * For backwards compatibility, initcall() puts the call in
 158  * the device init subsection.
 159  *
 160  * The `id' arg to __define_initcall() is needed so that multiple initcalls
 161  * can point at the same handler without causing duplicate-symbol build errors.
 162  */
 163
 164 #define __define_initcall(level,fn,id) \
 165         static initcall_t __initcall_##fn##id __used \
 166         __attribute__((__section__(".initcall" level ".init"))) = fn
 167
 168 /*
 169  * A "pure" initcall has no dependencies on anything else, and purely
 170  * initializes variables that couldn't be statically initialized.
 171  *
 172  * This only exists for built-in code, not for modules.
 173  */
 174 #define pure_initcall(fn)               __define_initcall("0",fn,0)
 175
 176 #define core_initcall(fn)               __define_initcall("1",fn,1)
 177 #define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
 178 #define postcore_initcall(fn)           __define_initcall("2",fn,2)
 179 #define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
 180 #define arch_initcall(fn)               __define_initcall("3",fn,3)
 181 #define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
 182 #define subsys_initcall(fn)             __define_initcall("4",fn,4)
 183 #define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
 184 #define fs_initcall(fn)                 __define_initcall("5",fn,5)
 185 #define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
 186 #define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
 187 #define device_initcall(fn)             __define_initcall("6",fn,6)
 188 #define device_initcall_sync(fn)        __define_initcall("6s",fn,6s)
 189 #define late_initcall(fn)               __define_initcall("7",fn,7)
 190 #define late_initcall_sync(fn)          __define_initcall("7s",fn,7s)
 191
 192 #define __initcall(fn) device_initcall(fn)
 193
 194 #define __exitcall(fn) \
 195         static exitcall_t __exitcall_##fn __exit_call = fn
 196
 197 #define console_initcall(fn) \
 198         static initcall_t __initcall_##fn \
 199         __used __section(.con_initcall.init) = fn
 200
 201 #define security_initcall(fn) \
 202         static initcall_t __initcall_##fn \
 203         __used __section(.security_initcall.init) = fn
 204
 205 struct obs_kernel_param {
 206         const char *str;
 207         int (*setup_func)(char *);
 208         int early;
 209 };
 210
 211 /*
 212  * Only for really core code.  See moduleparam.h for the normal way.
 213  *
 214  * Force the alignment so the compiler doesn't space elements of the
 215  * obs_kernel_param "array" too far apart in .init.setup.
 216  */
 217 #define __setup_param(str, unique_id, fn, early)                        \
 218         static char __setup_str_##unique_id[] __initdata __aligned(1) = str; \
 219         static struct obs_kernel_param __setup_##unique_id      \
 220                 __used __section(.init.setup)                   \
 221                 __attribute__((aligned((sizeof(long)))))        \
 222                 = { __setup_str_##unique_id, fn, early }
 223
 224 #define __setup_null_param(str, unique_id)                      \
 225         __setup_param(str, unique_id, NULL, 0)
 226
 227 #define __setup(str, fn)                                        \
 228         __setup_param(str, fn, fn, 0)
 229
 230 /* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 231  * returns non-zero. */
 232 #define early_param(str, fn)                                    \
 233         __setup_param(str, fn, fn, 1)
 234
 235 /* Relies on boot_command_line being set */
 236 void __init parse_early_param(void);
 237 #endif /* __ASSEMBLY__ */
 238
 239 /**
 240  * module_init() - driver initialization entry point
 241  * @x: function to be run at kernel boot time or module insertion
 242  *
 243  * module_init() will either be called during do_initcalls() (if
 244  * builtin) or at module insertion time (if a module).  There can only
 245  * be one per module.
 246  */
 247 #define module_init(x)  __initcall(x);
 248
 249 /**
 250  * module_exit() - driver exit entry point
 251  * @x: function to be run when driver is removed
 252  *
 253  * module_exit() will wrap the driver clean-up code
 254  * with cleanup_module() when used with rmmod when
 255  * the driver is a module.  If the driver is statically
 256  * compiled into the kernel, module_exit() has no effect.
 257  * There can only be one per module.
 258  */
 259 #define module_exit(x)  __exitcall(x);
 260
 261 #else /* MODULE */
 262
 263 /* Don't use these in modules, but some people do... */
 264 #define core_initcall(fn)               module_init(fn)
 265 #define postcore_initcall(fn)           module_init(fn)
 266 #define arch_initcall(fn)               module_init(fn)
 267 #define subsys_initcall(fn)             module_init(fn)
 268 #define fs_initcall(fn)                 module_init(fn)
 269 #define device_initcall(fn)             module_init(fn)
 270 #define late_initcall(fn)               module_init(fn)
 271
 272 #define security_initcall(fn)           module_init(fn)
 273
 274 /* These macros create a dummy inline: gcc 2.9x does not count alias
 275  as usage, hence the `unused function' warning when __init functions
 276  are declared static. We use the dummy __*_module_inline functions
 277  both to kill the warning and check the type of the init/cleanup
 278  function. */
 279
 280 /* Each module must use one module_init(), or one no_module_init */
 281 #define module_init(initfn)                                     \
 282         static inline initcall_t __inittest(void)               \
 283         { return initfn; }                                      \
 284         int init_module(void) __attribute__((alias(#initfn)));
 285
 286 /* This is only required if you want to be unloadable. */
 287 #define module_exit(exitfn)                                     \
 288         static inline exitcall_t __exittest(void)               \
 289         { return exitfn; }                                      \
 290         void cleanup_module(void) __attribute__((alias(#exitfn)));
 291
 292 #define __setup_param(str, unique_id, fn)       /* nothing */
 293 #define __setup_null_param(str, unique_id)      /* nothing */
 294 #define __setup(str, func)                      /* nothing */
 295 #endif
 296
 297 /* Data marked not to be saved by software suspend */
 298 #define __nosavedata __section(.data.nosave)
 299
 300 /* This means "can be init if no module support, otherwise module load
 301    may call it." */
 302 #ifdef CONFIG_MODULES
 303 #define __init_or_module
 304 #define __initdata_or_module
 305 #else
 306 #define __init_or_module __init
 307 #define __initdata_or_module __initdata
 308 #endif /*CONFIG_MODULES*/
 309
 310 /* Functions marked as __devexit may be discarded at kernel link time, depending
 311    on config options.  Newer versions of binutils detect references from
 312    retained sections to discarded sections and flag an error.  Pointers to
 313    __devexit functions must use __devexit_p(function_name), the wrapper will
 314    insert either the function_name or NULL, depending on the config options.
 315  */
 316 #if defined(MODULE) || defined(CONFIG_HOTPLUG)
 317 #define __devexit_p(x) x
 318 #else
 319 #define __devexit_p(x) NULL
 320 #endif
 321
 322 #ifdef MODULE
 323 #define __exit_p(x) x
 324 #else
 325 #define __exit_p(x) NULL
 326 #endif
 327
 328 #endif /* _LINUX_INIT_H */