linux/include/linux/init.h
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   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/* 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/* compatibility defines */
  64#define __init_refok     __ref
  65#define __initdata_refok __refdata
  66#define __exit_refok     __ref
  67
  68
  69#ifdef MODULE
  70#define __exitused
  71#else
  72#define __exitused  __used
  73#endif
  74
  75#define __exit          __section(.exit.text) __exitused __cold
  76
  77/* Used for HOTPLUG */
  78#define __devinit        __section(.devinit.text) __cold
  79#define __devinitdata    __section(.devinit.data)
  80#define __devinitconst   __section(.devinit.rodata)
  81#define __devexit        __section(.devexit.text) __exitused __cold
  82#define __devexitdata    __section(.devexit.data)
  83#define __devexitconst   __section(.devexit.rodata)
  84
  85/* Used for HOTPLUG_CPU */
  86#define __cpuinit        __section(.cpuinit.text) __cold
  87#define __cpuinitdata    __section(.cpuinit.data)
  88#define __cpuinitconst   __section(.cpuinit.rodata)
  89#define __cpuexit        __section(.cpuexit.text) __exitused __cold
  90#define __cpuexitdata    __section(.cpuexit.data)
  91#define __cpuexitconst   __section(.cpuexit.rodata)
  92
  93/* Used for MEMORY_HOTPLUG */
  94#define __meminit        __section(.meminit.text) __cold
  95#define __meminitdata    __section(.meminit.data)
  96#define __meminitconst   __section(.meminit.rodata)
  97#define __memexit        __section(.memexit.text) __exitused __cold
  98#define __memexitdata    __section(.memexit.data)
  99#define __memexitconst   __section(.memexit.rodata)
 100
 101/* For assembly routines */
 102#define __HEAD          .section        ".head.text","ax"
 103#define __INIT          .section        ".init.text","ax"
 104#define __FINIT         .previous
 105
 106#define __INITDATA      .section        ".init.data","aw",%progbits
 107#define __INITRODATA    .section        ".init.rodata","a",%progbits
 108#define __FINITDATA     .previous
 109
 110#define __DEVINIT        .section       ".devinit.text", "ax"
 111#define __DEVINITDATA    .section       ".devinit.data", "aw"
 112#define __DEVINITRODATA  .section       ".devinit.rodata", "a"
 113
 114#define __CPUINIT        .section       ".cpuinit.text", "ax"
 115#define __CPUINITDATA    .section       ".cpuinit.data", "aw"
 116#define __CPUINITRODATA  .section       ".cpuinit.rodata", "a"
 117
 118#define __MEMINIT        .section       ".meminit.text", "ax"
 119#define __MEMINITDATA    .section       ".meminit.data", "aw"
 120#define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 121
 122/* silence warnings when references are OK */
 123#define __REF            .section       ".ref.text", "ax"
 124#define __REFDATA        .section       ".ref.data", "aw"
 125#define __REFCONST       .section       ".ref.rodata", "a"
 126
 127#ifndef __ASSEMBLY__
 128/*
 129 * Used for initialization calls..
 130 */
 131typedef int (*initcall_t)(void);
 132typedef void (*exitcall_t)(void);
 133
 134extern initcall_t __con_initcall_start[], __con_initcall_end[];
 135extern initcall_t __security_initcall_start[], __security_initcall_end[];
 136
 137/* Used for contructor calls. */
 138typedef void (*ctor_fn_t)(void);
 139
 140/* Defined in init/main.c */
 141extern int do_one_initcall(initcall_t fn);
 142extern char __initdata boot_command_line[];
 143extern char *saved_command_line;
 144extern unsigned int reset_devices;
 145
 146/* used by init/main.c */
 147void setup_arch(char **);
 148void prepare_namespace(void);
 149
 150extern void (*late_time_init)(void);
 151
 152extern int initcall_debug;
 153
 154#endif
 155  
 156#ifndef MODULE
 157
 158#ifndef __ASSEMBLY__
 159
 160/* initcalls are now grouped by functionality into separate 
 161 * subsections. Ordering inside the subsections is determined
 162 * by link order. 
 163 * For backwards compatibility, initcall() puts the call in 
 164 * the device init subsection.
 165 *
 166 * The `id' arg to __define_initcall() is needed so that multiple initcalls
 167 * can point at the same handler without causing duplicate-symbol build errors.
 168 */
 169
 170#define __define_initcall(level,fn,id) \
 171        static initcall_t __initcall_##fn##id __used \
 172        __attribute__((__section__(".initcall" level ".init"))) = fn
 173
 174/*
 175 * Early initcalls run before initializing SMP.
 176 *
 177 * Only for built-in code, not modules.
 178 */
 179#define early_initcall(fn)              __define_initcall("early",fn,early)
 180
 181/*
 182 * A "pure" initcall has no dependencies on anything else, and purely
 183 * initializes variables that couldn't be statically initialized.
 184 *
 185 * This only exists for built-in code, not for modules.
 186 */
 187#define pure_initcall(fn)               __define_initcall("0",fn,0)
 188
 189#define core_initcall(fn)               __define_initcall("1",fn,1)
 190#define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
 191#define postcore_initcall(fn)           __define_initcall("2",fn,2)
 192#define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
 193#define arch_initcall(fn)               __define_initcall("3",fn,3)
 194#define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
 195#define subsys_initcall(fn)             __define_initcall("4",fn,4)
 196#define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
 197#define fs_initcall(fn)                 __define_initcall("5",fn,5)
 198#define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
 199#define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
 200#define device_initcall(fn)             __define_initcall("6",fn,6)
 201#define device_initcall_sync(fn)        __define_initcall("6s",fn,6s)
 202#define late_initcall(fn)               __define_initcall("7",fn,7)
 203#define late_initcall_sync(fn)          __define_initcall("7s",fn,7s)
 204
 205#define __initcall(fn) device_initcall(fn)
 206
 207#define __exitcall(fn) \
 208        static exitcall_t __exitcall_##fn __exit_call = fn
 209
 210#define console_initcall(fn) \
 211        static initcall_t __initcall_##fn \
 212        __used __section(.con_initcall.init) = fn
 213
 214#define security_initcall(fn) \
 215        static initcall_t __initcall_##fn \
 216        __used __section(.security_initcall.init) = fn
 217
 218struct obs_kernel_param {
 219        const char *str;
 220        int (*setup_func)(char *);
 221        int early;
 222};
 223
 224/*
 225 * Only for really core code.  See moduleparam.h for the normal way.
 226 *
 227 * Force the alignment so the compiler doesn't space elements of the
 228 * obs_kernel_param "array" too far apart in .init.setup.
 229 */
 230#define __setup_param(str, unique_id, fn, early)                        \
 231        static const char __setup_str_##unique_id[] __initconst \
 232                __aligned(1) = str; \
 233        static struct obs_kernel_param __setup_##unique_id      \
 234                __used __section(.init.setup)                   \
 235                __attribute__((aligned((sizeof(long)))))        \
 236                = { __setup_str_##unique_id, fn, early }
 237
 238#define __setup(str, fn)                                        \
 239        __setup_param(str, fn, fn, 0)
 240
 241/* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 242 * returns non-zero. */
 243#define early_param(str, fn)                                    \
 244        __setup_param(str, fn, fn, 1)
 245
 246/* Relies on boot_command_line being set */
 247void __init parse_early_param(void);
 248void __init parse_early_options(char *cmdline);
 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 early_initcall(fn)              module_init(fn)
 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#define __initconst_or_module
 312#define __INIT_OR_MODULE        .text
 313#define __INITDATA_OR_MODULE    .data
 314#define __INITRODATA_OR_MODULE  .section ".rodata","a",%progbits
 315#else
 316#define __init_or_module __init
 317#define __initdata_or_module __initdata
 318#define __initconst_or_module __initconst
 319#define __INIT_OR_MODULE __INIT
 320#define __INITDATA_OR_MODULE __INITDATA
 321#define __INITRODATA_OR_MODULE __INITRODATA
 322#endif /*CONFIG_MODULES*/
 323
 324/* Functions marked as __devexit may be discarded at kernel link time, depending
 325   on config options.  Newer versions of binutils detect references from
 326   retained sections to discarded sections and flag an error.  Pointers to
 327   __devexit functions must use __devexit_p(function_name), the wrapper will
 328   insert either the function_name or NULL, depending on the config options.
 329 */
 330#if defined(MODULE) || defined(CONFIG_HOTPLUG)
 331#define __devexit_p(x) x
 332#else
 333#define __devexit_p(x) NULL
 334#endif
 335
 336#ifdef MODULE
 337#define __exit_p(x) x
 338#else
 339#define __exit_p(x) NULL
 340#endif
 341
 342#endif /* _LINUX_INIT_H */
 343
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