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