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     __constsection(.init.rodata)
  47#define __exitdata      __section(.exit.data)
  48#define __exit_call     __used __section(.exitcall.exit)
  49
  50/*
  51 * Some architecture have tool chains which do not handle rodata attributes
  52 * correctly. For those disable special sections for const, so that other
  53 * architectures can annotate correctly.
  54 */
  55#ifdef CONFIG_BROKEN_RODATA
  56#define __constsection(x)
  57#else
  58#define __constsection(x) __section(x)
  59#endif
  60
  61/*
  62 * modpost check for section mismatches during the kernel build.
  63 * A section mismatch happens when there are references from a
  64 * code or data section to an init section (both code or data).
  65 * The init sections are (for most archs) discarded by the kernel
  66 * when early init has completed so all such references are potential bugs.
  67 * For exit sections the same issue exists.
  68 *
  69 * The following markers are used for the cases where the reference to
  70 * the *init / *exit section (code or data) is valid and will teach
  71 * modpost not to issue a warning.  Intended semantics is that a code or
  72 * data tagged __ref* can reference code or data from init section without
  73 * producing a warning (of course, no warning does not mean code is
  74 * correct, so optimally document why the __ref is needed and why it's OK).
  75 *
  76 * The markers follow same syntax rules as __init / __initdata.
  77 */
  78#define __ref            __section(.ref.text) noinline
  79#define __refdata        __section(.ref.data)
  80#define __refconst       __constsection(.ref.rodata)
  81
  82/* compatibility defines */
  83#define __init_refok     __ref
  84#define __initdata_refok __refdata
  85#define __exit_refok     __ref
  86
  87
  88#ifdef MODULE
  89#define __exitused
  90#else
  91#define __exitused  __used
  92#endif
  93
  94#define __exit          __section(.exit.text) __exitused __cold notrace
  95
  96/* Used for HOTPLUG */
  97#define __devinit        __section(.devinit.text) __cold notrace
  98#define __devinitdata    __section(.devinit.data)
  99#define __devinitconst   __constsection(.devinit.rodata)
 100#define __devexit        __section(.devexit.text) __exitused __cold notrace
 101#define __devexitdata    __section(.devexit.data)
 102#define __devexitconst   __constsection(.devexit.rodata)
 103
 104/* Used for HOTPLUG_CPU */
 105#define __cpuinit        __section(.cpuinit.text) __cold notrace
 106#define __cpuinitdata    __section(.cpuinit.data)
 107#define __cpuinitconst   __constsection(.cpuinit.rodata)
 108#define __cpuexit        __section(.cpuexit.text) __exitused __cold notrace
 109#define __cpuexitdata    __section(.cpuexit.data)
 110#define __cpuexitconst   __constsection(.cpuexit.rodata)
 111
 112/* Used for MEMORY_HOTPLUG */
 113#define __meminit        __section(.meminit.text) __cold notrace
 114#define __meminitdata    __section(.meminit.data)
 115#define __meminitconst   __constsection(.meminit.rodata)
 116#define __memexit        __section(.memexit.text) __exitused __cold notrace
 117#define __memexitdata    __section(.memexit.data)
 118#define __memexitconst   __constsection(.memexit.rodata)
 119
 120/* For assembly routines */
 121#define __HEAD          .section        ".head.text","ax"
 122#define __INIT          .section        ".init.text","ax"
 123#define __FINIT         .previous
 124
 125#define __INITDATA      .section        ".init.data","aw",%progbits
 126#define __INITRODATA    .section        ".init.rodata","a",%progbits
 127#define __FINITDATA     .previous
 128
 129#define __DEVINIT        .section       ".devinit.text", "ax"
 130#define __DEVINITDATA    .section       ".devinit.data", "aw"
 131#define __DEVINITRODATA  .section       ".devinit.rodata", "a"
 132
 133#define __CPUINIT        .section       ".cpuinit.text", "ax"
 134#define __CPUINITDATA    .section       ".cpuinit.data", "aw"
 135#define __CPUINITRODATA  .section       ".cpuinit.rodata", "a"
 136
 137#define __MEMINIT        .section       ".meminit.text", "ax"
 138#define __MEMINITDATA    .section       ".meminit.data", "aw"
 139#define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 140
 141/* silence warnings when references are OK */
 142#define __REF            .section       ".ref.text", "ax"
 143#define __REFDATA        .section       ".ref.data", "aw"
 144#define __REFCONST       .section       ".ref.rodata", "a"
 145
 146#ifndef __ASSEMBLY__
 147/*
 148 * Used for initialization calls..
 149 */
 150typedef int (*initcall_t)(void);
 151typedef void (*exitcall_t)(void);
 152
 153extern initcall_t __con_initcall_start[], __con_initcall_end[];
 154extern initcall_t __security_initcall_start[], __security_initcall_end[];
 155
 156/* Used for contructor calls. */
 157typedef void (*ctor_fn_t)(void);
 158
 159/* Defined in init/main.c */
 160extern int do_one_initcall(initcall_t fn);
 161extern char __initdata boot_command_line[];
 162extern char *saved_command_line;
 163extern unsigned int reset_devices;
 164
 165/* used by init/main.c */
 166void setup_arch(char **);
 167void prepare_namespace(void);
 168
 169extern void (*late_time_init)(void);
 170
 171extern bool initcall_debug;
 172
 173#endif
 174  
 175#ifndef MODULE
 176
 177#ifndef __ASSEMBLY__
 178
 179/* initcalls are now grouped by functionality into separate 
 180 * subsections. Ordering inside the subsections is determined
 181 * by link order. 
 182 * For backwards compatibility, initcall() puts the call in 
 183 * the device init subsection.
 184 *
 185 * The `id' arg to __define_initcall() is needed so that multiple initcalls
 186 * can point at the same handler without causing duplicate-symbol build errors.
 187 */
 188
 189#define __define_initcall(level,fn,id) \
 190        static initcall_t __initcall_##fn##id __used \
 191        __attribute__((__section__(".initcall" level ".init"))) = fn
 192
 193/*
 194 * Early initcalls run before initializing SMP.
 195 *
 196 * Only for built-in code, not modules.
 197 */
 198#define early_initcall(fn)              __define_initcall("early",fn,early)
 199
 200/*
 201 * A "pure" initcall has no dependencies on anything else, and purely
 202 * initializes variables that couldn't be statically initialized.
 203 *
 204 * This only exists for built-in code, not for modules.
 205 * Keep main.c:initcall_level_names[] in sync.
 206 */
 207#define pure_initcall(fn)               __define_initcall("0",fn,0)
 208
 209#define core_initcall(fn)               __define_initcall("1",fn,1)
 210#define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
 211#define postcore_initcall(fn)           __define_initcall("2",fn,2)
 212#define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
 213#define arch_initcall(fn)               __define_initcall("3",fn,3)
 214#define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
 215#define subsys_initcall(fn)             __define_initcall("4",fn,4)
 216#define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
 217#define fs_initcall(fn)                 __define_initcall("5",fn,5)
 218#define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
 219#define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
 220#define device_initcall(fn)             __define_initcall("6",fn,6)
 221#define device_initcall_sync(fn)        __define_initcall("6s",fn,6s)
 222#define late_initcall(fn)               __define_initcall("7",fn,7)
 223#define late_initcall_sync(fn)          __define_initcall("7s",fn,7s)
 224
 225#define __initcall(fn) device_initcall(fn)
 226
 227#define __exitcall(fn) \
 228        static exitcall_t __exitcall_##fn __exit_call = fn
 229
 230#define console_initcall(fn) \
 231        static initcall_t __initcall_##fn \
 232        __used __section(.con_initcall.init) = fn
 233
 234#define security_initcall(fn) \
 235        static initcall_t __initcall_##fn \
 236        __used __section(.security_initcall.init) = fn
 237
 238struct obs_kernel_param {
 239        const char *str;
 240        int (*setup_func)(char *);
 241        int early;
 242};
 243
 244/*
 245 * Only for really core code.  See moduleparam.h for the normal way.
 246 *
 247 * Force the alignment so the compiler doesn't space elements of the
 248 * obs_kernel_param "array" too far apart in .init.setup.
 249 */
 250#define __setup_param(str, unique_id, fn, early)                        \
 251        static const char __setup_str_##unique_id[] __initconst \
 252                __aligned(1) = str; \
 253        static struct obs_kernel_param __setup_##unique_id      \
 254                __used __section(.init.setup)                   \
 255                __attribute__((aligned((sizeof(long)))))        \
 256                = { __setup_str_##unique_id, fn, early }
 257
 258#define __setup(str, fn)                                        \
 259        __setup_param(str, fn, fn, 0)
 260
 261/* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 262 * returns non-zero. */
 263#define early_param(str, fn)                                    \
 264        __setup_param(str, fn, fn, 1)
 265
 266/* Relies on boot_command_line being set */
 267void __init parse_early_param(void);
 268void __init parse_early_options(char *cmdline);
 269#endif /* __ASSEMBLY__ */
 270
 271/**
 272 * module_init() - driver initialization entry point
 273 * @x: function to be run at kernel boot time or module insertion
 274 * 
 275 * module_init() will either be called during do_initcalls() (if
 276 * builtin) or at module insertion time (if a module).  There can only
 277 * be one per module.
 278 */
 279#define module_init(x)  __initcall(x);
 280
 281/**
 282 * module_exit() - driver exit entry point
 283 * @x: function to be run when driver is removed
 284 * 
 285 * module_exit() will wrap the driver clean-up code
 286 * with cleanup_module() when used with rmmod when
 287 * the driver is a module.  If the driver is statically
 288 * compiled into the kernel, module_exit() has no effect.
 289 * There can only be one per module.
 290 */
 291#define module_exit(x)  __exitcall(x);
 292
 293#else /* MODULE */
 294
 295/* Don't use these in loadable modules, but some people do... */
 296#define early_initcall(fn)              module_init(fn)
 297#define core_initcall(fn)               module_init(fn)
 298#define postcore_initcall(fn)           module_init(fn)
 299#define arch_initcall(fn)               module_init(fn)
 300#define subsys_initcall(fn)             module_init(fn)
 301#define fs_initcall(fn)                 module_init(fn)
 302#define device_initcall(fn)             module_init(fn)
 303#define late_initcall(fn)               module_init(fn)
 304
 305#define security_initcall(fn)           module_init(fn)
 306
 307/* Each module must use one module_init(). */
 308#define module_init(initfn)                                     \
 309        static inline initcall_t __inittest(void)               \
 310        { return initfn; }                                      \
 311        int init_module(void) __attribute__((alias(#initfn)));
 312
 313/* This is only required if you want to be unloadable. */
 314#define module_exit(exitfn)                                     \
 315        static inline exitcall_t __exittest(void)               \
 316        { return exitfn; }                                      \
 317        void cleanup_module(void) __attribute__((alias(#exitfn)));
 318
 319#define __setup_param(str, unique_id, fn)       /* nothing */
 320#define __setup(str, func)                      /* nothing */
 321#endif
 322
 323/* Data marked not to be saved by software suspend */
 324#define __nosavedata __section(.data..nosave)
 325
 326/* This means "can be init if no module support, otherwise module load
 327   may call it." */
 328#ifdef CONFIG_MODULES
 329#define __init_or_module
 330#define __initdata_or_module
 331#define __initconst_or_module
 332#define __INIT_OR_MODULE        .text
 333#define __INITDATA_OR_MODULE    .data
 334#define __INITRODATA_OR_MODULE  .section ".rodata","a",%progbits
 335#else
 336#define __init_or_module __init
 337#define __initdata_or_module __initdata
 338#define __initconst_or_module __initconst
 339#define __INIT_OR_MODULE __INIT
 340#define __INITDATA_OR_MODULE __INITDATA
 341#define __INITRODATA_OR_MODULE __INITRODATA
 342#endif /*CONFIG_MODULES*/
 343
 344/* Functions marked as __devexit may be discarded at kernel link time, depending
 345   on config options.  Newer versions of binutils detect references from
 346   retained sections to discarded sections and flag an error.  Pointers to
 347   __devexit functions must use __devexit_p(function_name), the wrapper will
 348   insert either the function_name or NULL, depending on the config options.
 349 */
 350#if defined(MODULE) || defined(CONFIG_HOTPLUG)
 351#define __devexit_p(x) x
 352#else
 353#define __devexit_p(x) NULL
 354#endif
 355
 356#ifdef MODULE
 357#define __exit_p(x) x
 358#else
 359#define __exit_p(x) NULL
 360#endif
 361
 362#endif /* _LINUX_INIT_H */
 363
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