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#include <linux/types.h>
   6
   7/* These macros are used to mark some functions or 
   8 * initialized data (doesn't apply to uninitialized data)
   9 * as `initialization' functions. The kernel can take this
  10 * as hint that the function is used only during the initialization
  11 * phase and free up used memory resources after
  12 *
  13 * Usage:
  14 * For functions:
  15 * 
  16 * You should add __init immediately before the function name, like:
  17 *
  18 * static void __init initme(int x, int y)
  19 * {
  20 *    extern int z; z = x * y;
  21 * }
  22 *
  23 * If the function has a prototype somewhere, you can also add
  24 * __init between closing brace of the prototype and semicolon:
  25 *
  26 * extern int initialize_foobar_device(int, int, int) __init;
  27 *
  28 * For initialized data:
  29 * You should insert __initdata between the variable name and equal
  30 * sign followed by value, e.g.:
  31 *
  32 * static int init_variable __initdata = 0;
  33 * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
  34 *
  35 * Don't forget to initialize data not at file scope, i.e. within a function,
  36 * as gcc otherwise puts the data into the bss section and not into the init
  37 * section.
  38 * 
  39 * Also note, that this data cannot be "const".
  40 */
  41
  42/* These are for everybody (although not all archs will actually
  43   discard it in modules) */
  44#define __init          __section(.init.text) __cold notrace
  45#define __initdata      __section(.init.data)
  46#define __initconst     __section(.init.rodata)
  47#define __exitdata      __section(.exit.data)
  48#define __exit_call     __used __section(.exitcall.exit)
  49
  50/*
  51 * modpost check for section mismatches during the kernel build.
  52 * A section mismatch happens when there are references from a
  53 * code or data section to an init section (both code or data).
  54 * The init sections are (for most archs) discarded by the kernel
  55 * when early init has completed so all such references are potential bugs.
  56 * For exit sections the same issue exists.
  57 *
  58 * The following markers are used for the cases where the reference to
  59 * the *init / *exit section (code or data) is valid and will teach
  60 * modpost not to issue a warning.  Intended semantics is that a code or
  61 * data tagged __ref* can reference code or data from init section without
  62 * producing a warning (of course, no warning does not mean code is
  63 * correct, so optimally document why the __ref is needed and why it's OK).
  64 *
  65 * The markers follow same syntax rules as __init / __initdata.
  66 */
  67#define __ref            __section(.ref.text) noinline
  68#define __refdata        __section(.ref.data)
  69#define __refconst       __section(.ref.rodata)
  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 notrace
  84
  85/* Used for HOTPLUG */
  86#define __devinit        __section(.devinit.text) __cold notrace
  87#define __devinitdata    __section(.devinit.data)
  88#define __devinitconst   __section(.devinit.rodata)
  89#define __devexit        __section(.devexit.text) __exitused __cold notrace
  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 notrace
  95#define __cpuinitdata    __section(.cpuinit.data)
  96#define __cpuinitconst   __section(.cpuinit.rodata)
  97#define __cpuexit        __section(.cpuexit.text) __exitused __cold notrace
  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 notrace
 103#define __meminitdata    __section(.meminit.data)
 104#define __meminitconst   __section(.meminit.rodata)
 105#define __memexit        __section(.memexit.text) __exitused __cold notrace
 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",%progbits
 115#define __INITRODATA    .section        ".init.rodata","a",%progbits
 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 */
 139typedef int (*initcall_t)(void);
 140typedef void (*exitcall_t)(void);
 141
 142extern initcall_t __con_initcall_start[], __con_initcall_end[];
 143extern initcall_t __security_initcall_start[], __security_initcall_end[];
 144
 145/* Used for contructor calls. */
 146typedef void (*ctor_fn_t)(void);
 147
 148/* Defined in init/main.c */
 149extern int do_one_initcall(initcall_t fn);
 150extern char __initdata boot_command_line[];
 151extern char *saved_command_line;
 152extern unsigned int reset_devices;
 153
 154/* used by init/main.c */
 155void setup_arch(char **);
 156void prepare_namespace(void);
 157
 158extern void (*late_time_init)(void);
 159
 160extern bool initcall_debug;
 161
 162#endif
 163  
 164#ifndef MODULE
 165
 166#ifndef __ASSEMBLY__
 167
 168/* initcalls are now grouped by functionality into separate 
 169 * subsections. Ordering inside the subsections is determined
 170 * by link order. 
 171 * For backwards compatibility, initcall() puts the call in 
 172 * the device init subsection.
 173 *
 174 * The `id' arg to __define_initcall() is needed so that multiple initcalls
 175 * can point at the same handler without causing duplicate-symbol build errors.
 176 */
 177
 178#define __define_initcall(level,fn,id) \
 179        static initcall_t __initcall_##fn##id __used \
 180        __attribute__((__section__(".initcall" level ".init"))) = fn
 181
 182/*
 183 * Early initcalls run before initializing SMP.
 184 *
 185 * Only for built-in code, not modules.
 186 */
 187#define early_initcall(fn)              __define_initcall("early",fn,early)
 188
 189/*
 190 * A "pure" initcall has no dependencies on anything else, and purely
 191 * initializes variables that couldn't be statically initialized.
 192 *
 193 * This only exists for built-in code, not for modules.
 194 * Keep main.c:initcall_level_names[] in sync.
 195 */
 196#define pure_initcall(fn)               __define_initcall("0",fn,0)
 197
 198#define core_initcall(fn)               __define_initcall("1",fn,1)
 199#define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
 200#define postcore_initcall(fn)           __define_initcall("2",fn,2)
 201#define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
 202#define arch_initcall(fn)               __define_initcall("3",fn,3)
 203#define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
 204#define subsys_initcall(fn)             __define_initcall("4",fn,4)
 205#define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
 206#define fs_initcall(fn)                 __define_initcall("5",fn,5)
 207#define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
 208#define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
 209#define device_initcall(fn)             __define_initcall("6",fn,6)
 210#define device_initcall_sync(fn)        __define_initcall("6s",fn,6s)
 211#define late_initcall(fn)               __define_initcall("7",fn,7)
 212#define late_initcall_sync(fn)          __define_initcall("7s",fn,7s)
 213
 214#define __initcall(fn) device_initcall(fn)
 215
 216#define __exitcall(fn) \
 217        static exitcall_t __exitcall_##fn __exit_call = fn
 218
 219#define console_initcall(fn) \
 220        static initcall_t __initcall_##fn \
 221        __used __section(.con_initcall.init) = fn
 222
 223#define security_initcall(fn) \
 224        static initcall_t __initcall_##fn \
 225        __used __section(.security_initcall.init) = fn
 226
 227struct obs_kernel_param {
 228        const char *str;
 229        int (*setup_func)(char *);
 230        int early;
 231};
 232
 233/*
 234 * Only for really core code.  See moduleparam.h for the normal way.
 235 *
 236 * Force the alignment so the compiler doesn't space elements of the
 237 * obs_kernel_param "array" too far apart in .init.setup.
 238 */
 239#define __setup_param(str, unique_id, fn, early)                        \
 240        static const char __setup_str_##unique_id[] __initconst \
 241                __aligned(1) = str; \
 242        static struct obs_kernel_param __setup_##unique_id      \
 243                __used __section(.init.setup)                   \
 244                __attribute__((aligned((sizeof(long)))))        \
 245                = { __setup_str_##unique_id, fn, early }
 246
 247#define __setup(str, fn)                                        \
 248        __setup_param(str, fn, fn, 0)
 249
 250/* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 251 * returns non-zero. */
 252#define early_param(str, fn)                                    \
 253        __setup_param(str, fn, fn, 1)
 254
 255/* Relies on boot_command_line being set */
 256void __init parse_early_param(void);
 257void __init parse_early_options(char *cmdline);
 258#endif /* __ASSEMBLY__ */
 259
 260/**
 261 * module_init() - driver initialization entry point
 262 * @x: function to be run at kernel boot time or module insertion
 263 * 
 264 * module_init() will either be called during do_initcalls() (if
 265 * builtin) or at module insertion time (if a module).  There can only
 266 * be one per module.
 267 */
 268#define module_init(x)  __initcall(x);
 269
 270/**
 271 * module_exit() - driver exit entry point
 272 * @x: function to be run when driver is removed
 273 * 
 274 * module_exit() will wrap the driver clean-up code
 275 * with cleanup_module() when used with rmmod when
 276 * the driver is a module.  If the driver is statically
 277 * compiled into the kernel, module_exit() has no effect.
 278 * There can only be one per module.
 279 */
 280#define module_exit(x)  __exitcall(x);
 281
 282#else /* MODULE */
 283
 284/* Don't use these in loadable modules, but some people do... */
 285#define early_initcall(fn)              module_init(fn)
 286#define core_initcall(fn)               module_init(fn)
 287#define postcore_initcall(fn)           module_init(fn)
 288#define arch_initcall(fn)               module_init(fn)
 289#define subsys_initcall(fn)             module_init(fn)
 290#define fs_initcall(fn)                 module_init(fn)
 291#define device_initcall(fn)             module_init(fn)
 292#define late_initcall(fn)               module_init(fn)
 293
 294#define security_initcall(fn)           module_init(fn)
 295
 296/* Each module must use one module_init(). */
 297#define module_init(initfn)                                     \
 298        static inline initcall_t __inittest(void)               \
 299        { return initfn; }                                      \
 300        int init_module(void) __attribute__((alias(#initfn)));
 301
 302/* This is only required if you want to be unloadable. */
 303#define module_exit(exitfn)                                     \
 304        static inline exitcall_t __exittest(void)               \
 305        { return exitfn; }                                      \
 306        void cleanup_module(void) __attribute__((alias(#exitfn)));
 307
 308#define __setup_param(str, unique_id, fn)       /* nothing */
 309#define __setup(str, func)                      /* nothing */
 310#endif
 311
 312/* Data marked not to be saved by software suspend */
 313#define __nosavedata __section(.data..nosave)
 314
 315/* This means "can be init if no module support, otherwise module load
 316   may call it." */
 317#ifdef CONFIG_MODULES
 318#define __init_or_module
 319#define __initdata_or_module
 320#define __initconst_or_module
 321#define __INIT_OR_MODULE        .text
 322#define __INITDATA_OR_MODULE    .data
 323#define __INITRODATA_OR_MODULE  .section ".rodata","a",%progbits
 324#else
 325#define __init_or_module __init
 326#define __initdata_or_module __initdata
 327#define __initconst_or_module __initconst
 328#define __INIT_OR_MODULE __INIT
 329#define __INITDATA_OR_MODULE __INITDATA
 330#define __INITRODATA_OR_MODULE __INITRODATA
 331#endif /*CONFIG_MODULES*/
 332
 333/* Functions marked as __devexit may be discarded at kernel link time, depending
 334   on config options.  Newer versions of binutils detect references from
 335   retained sections to discarded sections and flag an error.  Pointers to
 336   __devexit functions must use __devexit_p(function_name), the wrapper will
 337   insert either the function_name or NULL, depending on the config options.
 338 */
 339#if defined(MODULE) || defined(CONFIG_HOTPLUG)
 340#define __devexit_p(x) x
 341#else
 342#define __devexit_p(x) NULL
 343#endif
 344
 345#ifdef MODULE
 346#define __exit_p(x) x
 347#else
 348#define __exit_p(x) NULL
 349#endif
 350
 351#endif /* _LINUX_INIT_H */
 352
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