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_CPU */
  97#define __cpuinit        __section(.cpuinit.text) __cold notrace
  98#define __cpuinitdata    __section(.cpuinit.data)
  99#define __cpuinitconst   __constsection(.cpuinit.rodata)
 100#define __cpuexit        __section(.cpuexit.text) __exitused __cold notrace
 101#define __cpuexitdata    __section(.cpuexit.data)
 102#define __cpuexitconst   __constsection(.cpuexit.rodata)
 103
 104/* Used for MEMORY_HOTPLUG */
 105#define __meminit        __section(.meminit.text) __cold notrace
 106#define __meminitdata    __section(.meminit.data)
 107#define __meminitconst   __constsection(.meminit.rodata)
 108#define __memexit        __section(.memexit.text) __exitused __cold notrace
 109#define __memexitdata    __section(.memexit.data)
 110#define __memexitconst   __constsection(.memexit.rodata)
 111
 112/* For assembly routines */
 113#define __HEAD          .section        ".head.text","ax"
 114#define __INIT          .section        ".init.text","ax"
 115#define __FINIT         .previous
 116
 117#define __INITDATA      .section        ".init.data","aw",%progbits
 118#define __INITRODATA    .section        ".init.rodata","a",%progbits
 119#define __FINITDATA     .previous
 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 */
 138typedef int (*initcall_t)(void);
 139typedef void (*exitcall_t)(void);
 140
 141extern initcall_t __con_initcall_start[], __con_initcall_end[];
 142extern initcall_t __security_initcall_start[], __security_initcall_end[];
 143
 144/* Used for contructor calls. */
 145typedef void (*ctor_fn_t)(void);
 146
 147/* Defined in init/main.c */
 148extern int do_one_initcall(initcall_t fn);
 149extern char __initdata boot_command_line[];
 150extern char *saved_command_line;
 151extern unsigned int reset_devices;
 152
 153/* used by init/main.c */
 154void setup_arch(char **);
 155void prepare_namespace(void);
 156
 157extern void (*late_time_init)(void);
 158
 159extern bool 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(fn, id) \
 178        static initcall_t __initcall_##fn##id __used \
 179        __attribute__((__section__(".initcall" #id ".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(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 * Keep main.c:initcall_level_names[] in sync.
 194 */
 195#define pure_initcall(fn)               __define_initcall(fn, 0)
 196
 197#define core_initcall(fn)               __define_initcall(fn, 1)
 198#define core_initcall_sync(fn)          __define_initcall(fn, 1s)
 199#define postcore_initcall(fn)           __define_initcall(fn, 2)
 200#define postcore_initcall_sync(fn)      __define_initcall(fn, 2s)
 201#define arch_initcall(fn)               __define_initcall(fn, 3)
 202#define arch_initcall_sync(fn)          __define_initcall(fn, 3s)
 203#define subsys_initcall(fn)             __define_initcall(fn, 4)
 204#define subsys_initcall_sync(fn)        __define_initcall(fn, 4s)
 205#define fs_initcall(fn)                 __define_initcall(fn, 5)
 206#define fs_initcall_sync(fn)            __define_initcall(fn, 5s)
 207#define rootfs_initcall(fn)             __define_initcall(fn, rootfs)
 208#define device_initcall(fn)             __define_initcall(fn, 6)
 209#define device_initcall_sync(fn)        __define_initcall(fn, 6s)
 210#define late_initcall(fn)               __define_initcall(fn, 7)
 211#define late_initcall_sync(fn)          __define_initcall(fn, 7s)
 212
 213#define __initcall(fn) device_initcall(fn)
 214
 215#define __exitcall(fn) \
 216        static exitcall_t __exitcall_##fn __exit_call = fn
 217
 218#define console_initcall(fn) \
 219        static initcall_t __initcall_##fn \
 220        __used __section(.con_initcall.init) = fn
 221
 222#define security_initcall(fn) \
 223        static initcall_t __initcall_##fn \
 224        __used __section(.security_initcall.init) = fn
 225
 226struct obs_kernel_param {
 227        const char *str;
 228        int (*setup_func)(char *);
 229        int early;
 230};
 231
 232/*
 233 * Only for really core code.  See moduleparam.h for the normal way.
 234 *
 235 * Force the alignment so the compiler doesn't space elements of the
 236 * obs_kernel_param "array" too far apart in .init.setup.
 237 */
 238#define __setup_param(str, unique_id, fn, early)                        \
 239        static const char __setup_str_##unique_id[] __initconst \
 240                __aligned(1) = str; \
 241        static struct obs_kernel_param __setup_##unique_id      \
 242                __used __section(.init.setup)                   \
 243                __attribute__((aligned((sizeof(long)))))        \
 244                = { __setup_str_##unique_id, fn, early }
 245
 246#define __setup(str, fn)                                        \
 247        __setup_param(str, fn, fn, 0)
 248
 249/* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 250 * returns non-zero. */
 251#define early_param(str, fn)                                    \
 252        __setup_param(str, fn, fn, 1)
 253
 254/* Relies on boot_command_line being set */
 255void __init parse_early_param(void);
 256void __init parse_early_options(char *cmdline);
 257#endif /* __ASSEMBLY__ */
 258
 259/**
 260 * module_init() - driver initialization entry point
 261 * @x: function to be run at kernel boot time or module insertion
 262 * 
 263 * module_init() will either be called during do_initcalls() (if
 264 * builtin) or at module insertion time (if a module).  There can only
 265 * be one per module.
 266 */
 267#define module_init(x)  __initcall(x);
 268
 269/**
 270 * module_exit() - driver exit entry point
 271 * @x: function to be run when driver is removed
 272 * 
 273 * module_exit() will wrap the driver clean-up code
 274 * with cleanup_module() when used with rmmod when
 275 * the driver is a module.  If the driver is statically
 276 * compiled into the kernel, module_exit() has no effect.
 277 * There can only be one per module.
 278 */
 279#define module_exit(x)  __exitcall(x);
 280
 281#else /* MODULE */
 282
 283/* Don't use these in loadable modules, but some people do... */
 284#define early_initcall(fn)              module_init(fn)
 285#define core_initcall(fn)               module_init(fn)
 286#define postcore_initcall(fn)           module_init(fn)
 287#define arch_initcall(fn)               module_init(fn)
 288#define subsys_initcall(fn)             module_init(fn)
 289#define fs_initcall(fn)                 module_init(fn)
 290#define device_initcall(fn)             module_init(fn)
 291#define late_initcall(fn)               module_init(fn)
 292
 293#define security_initcall(fn)           module_init(fn)
 294
 295/* Each module must use one module_init(). */
 296#define module_init(initfn)                                     \
 297        static inline initcall_t __inittest(void)               \
 298        { return initfn; }                                      \
 299        int init_module(void) __attribute__((alias(#initfn)));
 300
 301/* This is only required if you want to be unloadable. */
 302#define module_exit(exitfn)                                     \
 303        static inline exitcall_t __exittest(void)               \
 304        { return exitfn; }                                      \
 305        void cleanup_module(void) __attribute__((alias(#exitfn)));
 306
 307#define __setup_param(str, unique_id, fn)       /* nothing */
 308#define __setup(str, func)                      /* nothing */
 309#endif
 310
 311/* Data marked not to be saved by software suspend */
 312#define __nosavedata __section(.data..nosave)
 313
 314/* This means "can be init if no module support, otherwise module load
 315   may call it." */
 316#ifdef CONFIG_MODULES
 317#define __init_or_module
 318#define __initdata_or_module
 319#define __initconst_or_module
 320#define __INIT_OR_MODULE        .text
 321#define __INITDATA_OR_MODULE    .data
 322#define __INITRODATA_OR_MODULE  .section ".rodata","a",%progbits
 323#else
 324#define __init_or_module __init
 325#define __initdata_or_module __initdata
 326#define __initconst_or_module __initconst
 327#define __INIT_OR_MODULE __INIT
 328#define __INITDATA_OR_MODULE __INITDATA
 329#define __INITRODATA_OR_MODULE __INITRODATA
 330#endif /*CONFIG_MODULES*/
 331
 332#ifdef MODULE
 333#define __exit_p(x) x
 334#else
 335#define __exit_p(x) NULL
 336#endif
 337
 338#endif /* _LINUX_INIT_H */
 339
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