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