include/linux/init.h

   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 or __initconst between the variable name
  30  * and equal 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
  40 /* These are for everybody (although not all archs will actually
  41    discard it in modules) */
  42 #define __init          __section(.init.text) __cold notrace
  43 #define __initdata      __section(.init.data)
  44 #define __initconst     __constsection(.init.rodata)
  45 #define __exitdata      __section(.exit.data)
  46 #define __exit_call     __used __section(.exitcall.exit)
  47
  48 /*
  49  * Some architecture have tool chains which do not handle rodata attributes
  50  * correctly. For those disable special sections for const, so that other
  51  * architectures can annotate correctly.
  52  */
  53 #ifdef CONFIG_BROKEN_RODATA
  54 #define __constsection(x)
  55 #else
  56 #define __constsection(x) __section(x)
  57 #endif
  58
  59 /*
  60  * modpost check for section mismatches during the kernel build.
  61  * A section mismatch happens when there are references from a
  62  * code or data section to an init section (both code or data).
  63  * The init sections are (for most archs) discarded by the kernel
  64  * when early init has completed so all such references are potential bugs.
  65  * For exit sections the same issue exists.
  66  *
  67  * The following markers are used for the cases where the reference to
  68  * the *init / *exit section (code or data) is valid and will teach
  69  * modpost not to issue a warning.  Intended semantics is that a code or
  70  * data tagged __ref* can reference code or data from init section without
  71  * producing a warning (of course, no warning does not mean code is
  72  * correct, so optimally document why the __ref is needed and why it's OK).
  73  *
  74  * The markers follow same syntax rules as __init / __initdata.
  75  */
  76 #define __ref            __section(.ref.text) noinline
  77 #define __refdata        __section(.ref.data)
  78 #define __refconst       __constsection(.ref.rodata)
  79
  80 /* compatibility defines */
  81 #define __init_refok     __ref
  82 #define __initdata_refok __refdata
  83 #define __exit_refok     __ref
  84
  85
  86 #ifdef MODULE
  87 #define __exitused
  88 #else
  89 #define __exitused  __used
  90 #endif
  91
  92 #define __exit          __section(.exit.text) __exitused __cold notrace
  93
  94 /* temporary, until all users are removed */
  95 #define __cpuinit
  96 #define __cpuinitdata
  97 #define __cpuinitconst
  98 #define __cpuexit
  99 #define __cpuexitdata
 100 #define __cpuexitconst
 101
 102 /* Used for MEMORY_HOTPLUG */
 103 #define __meminit        __section(.meminit.text) __cold notrace
 104 #define __meminitdata    __section(.meminit.data)
 105 #define __meminitconst   __constsection(.meminit.rodata)
 106 #define __memexit        __section(.memexit.text) __exitused __cold notrace
 107 #define __memexitdata    __section(.memexit.data)
 108 #define __memexitconst   __constsection(.memexit.rodata)
 109
 110 /* For assembly routines */
 111 #define __HEAD          .section        ".head.text","ax"
 112 #define __INIT          .section        ".init.text","ax"
 113 #define __FINIT         .previous
 114
 115 #define __INITDATA      .section        ".init.data","aw",%progbits
 116 #define __INITRODATA    .section        ".init.rodata","a",%progbits
 117 #define __FINITDATA     .previous
 118
 119 /* temporary, until all users are removed */
 120 #define __CPUINIT
 121
 122 #define __MEMINIT        .section       ".meminit.text", "ax"
 123 #define __MEMINITDATA    .section       ".meminit.data", "aw"
 124 #define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 125
 126 /* silence warnings when references are OK */
 127 #define __REF            .section       ".ref.text", "ax"
 128 #define __REFDATA        .section       ".ref.data", "aw"
 129 #define __REFCONST       .section       ".ref.rodata", "a"
 130
 131 #ifndef __ASSEMBLY__
 132 /*
 133  * Used for initialization calls..
 134  */
 135 typedef int (*initcall_t)(void);
 136 typedef void (*exitcall_t)(void);
 137
 138 extern initcall_t __con_initcall_start[], __con_initcall_end[];
 139 extern initcall_t __security_initcall_start[], __security_initcall_end[];
 140
 141 /* Used for contructor calls. */
 142 typedef void (*ctor_fn_t)(void);
 143
 144 /* Defined in init/main.c */
 145 extern int do_one_initcall(initcall_t fn);
 146 extern char __initdata boot_command_line[];
 147 extern char *saved_command_line;
 148 extern unsigned int reset_devices;
 149
 150 /* used by init/main.c */
 151 void setup_arch(char **);
 152 void prepare_namespace(void);
 153 void __init load_default_modules(void);
 154 int __init init_rootfs(void);
 155
 156 extern void (*late_time_init)(void);
 157
 158 extern bool initcall_debug;
 159
 160 #endif
 161
 162 #ifndef MODULE
 163
 164 #ifndef __ASSEMBLY__
 165
 166 #ifdef CONFIG_LTO
 167 /* Work around a LTO gcc problem: when there is no reference to a variable
 168  * in a module it will be moved to the end of the program. This causes
 169  * reordering of initcalls which the kernel does not like.
 170  * Add a dummy reference function to avoid this. The function is
 171  * deleted by the linker.
 172  */
 173 #define LTO_REFERENCE_INITCALL(x) \
 174         ; /* yes this is needed */                      \
 175         static __used __exit void *reference_##x(void)  \
 176         {                                               \
 177                 return &x;                              \
 178         }
 179 #else
 180 #define LTO_REFERENCE_INITCALL(x)
 181 #endif
 182
 183 /* initcalls are now grouped by functionality into separate
 184  * subsections. Ordering inside the subsections is determined
 185  * by link order.
 186  * For backwards compatibility, initcall() puts the call in
 187  * the device init subsection.
 188  *
 189  * The `id' arg to __define_initcall() is needed so that multiple initcalls
 190  * can point at the same handler without causing duplicate-symbol build errors.
 191  */
 192
 193 #define __define_initcall(fn, id) \
 194         static initcall_t __initcall_##fn##id __used \
 195         __attribute__((__section__(".initcall" #id ".init"))) = fn; \
 196         LTO_REFERENCE_INITCALL(__initcall_##fn##id)
 197
 198 /*
 199  * Early initcalls run before initializing SMP.
 200  *
 201  * Only for built-in code, not modules.
 202  */
 203 #define early_initcall(fn)              __define_initcall(fn, early)
 204
 205 /*
 206  * A "pure" initcall has no dependencies on anything else, and purely
 207  * initializes variables that couldn't be statically initialized.
 208  *
 209  * This only exists for built-in code, not for modules.
 210  * Keep main.c:initcall_level_names[] in sync.
 211  */
 212 #define pure_initcall(fn)               __define_initcall(fn, 0)
 213
 214 #define core_initcall(fn)               __define_initcall(fn, 1)
 215 #define core_initcall_sync(fn)          __define_initcall(fn, 1s)
 216 #define postcore_initcall(fn)           __define_initcall(fn, 2)
 217 #define postcore_initcall_sync(fn)      __define_initcall(fn, 2s)
 218 #define arch_initcall(fn)               __define_initcall(fn, 3)
 219 #define arch_initcall_sync(fn)          __define_initcall(fn, 3s)
 220 #define subsys_initcall(fn)             __define_initcall(fn, 4)
 221 #define subsys_initcall_sync(fn)        __define_initcall(fn, 4s)
 222 #define fs_initcall(fn)                 __define_initcall(fn, 5)
 223 #define fs_initcall_sync(fn)            __define_initcall(fn, 5s)
 224 #define rootfs_initcall(fn)             __define_initcall(fn, rootfs)
 225 #define device_initcall(fn)             __define_initcall(fn, 6)
 226 #define device_initcall_sync(fn)        __define_initcall(fn, 6s)
 227 #define late_initcall(fn)               __define_initcall(fn, 7)
 228 #define late_initcall_sync(fn)          __define_initcall(fn, 7s)
 229
 230 #define __initcall(fn) device_initcall(fn)
 231
 232 #define __exitcall(fn) \
 233         static exitcall_t __exitcall_##fn __exit_call = fn
 234
 235 #define console_initcall(fn) \
 236         static initcall_t __initcall_##fn \
 237         __used __section(.con_initcall.init) = fn
 238
 239 #define security_initcall(fn) \
 240         static initcall_t __initcall_##fn \
 241         __used __section(.security_initcall.init) = fn
 242
 243 struct obs_kernel_param {
 244         const char *str;
 245         int (*setup_func)(char *);
 246         int early;
 247 };
 248
 249 /*
 250  * Only for really core code.  See moduleparam.h for the normal way.
 251  *
 252  * Force the alignment so the compiler doesn't space elements of the
 253  * obs_kernel_param "array" too far apart in .init.setup.
 254  */
 255 #define __setup_param(str, unique_id, fn, early)                        \
 256         static const char __setup_str_##unique_id[] __initconst \
 257                 __aligned(1) = str; \
 258         static struct obs_kernel_param __setup_##unique_id      \
 259                 __used __section(.init.setup)                   \
 260                 __attribute__((aligned((sizeof(long)))))        \
 261                 = { __setup_str_##unique_id, fn, early }
 262
 263 #define __setup(str, fn)                                        \
 264         __setup_param(str, fn, fn, 0)
 265
 266 /* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 267  * returns non-zero. */
 268 #define early_param(str, fn)                                    \
 269         __setup_param(str, fn, fn, 1)
 270
 271 /* Relies on boot_command_line being set */
 272 void __init parse_early_param(void);
 273 void __init parse_early_options(char *cmdline);
 274 #endif /* __ASSEMBLY__ */
 275
 276 /**
 277  * module_init() - driver initialization entry point
 278  * @x: function to be run at kernel boot time or module insertion
 279  *
 280  * module_init() will either be called during do_initcalls() (if
 281  * builtin) or at module insertion time (if a module).  There can only
 282  * be one per module.
 283  */
 284 #define module_init(x)  __initcall(x);
 285
 286 /**
 287  * module_exit() - driver exit entry point
 288  * @x: function to be run when driver is removed
 289  *
 290  * module_exit() will wrap the driver clean-up code
 291  * with cleanup_module() when used with rmmod when
 292  * the driver is a module.  If the driver is statically
 293  * compiled into the kernel, module_exit() has no effect.
 294  * There can only be one per module.
 295  */
 296 #define module_exit(x)  __exitcall(x);
 297
 298 #else /* MODULE */
 299
 300 /*
 301  * In most cases loadable modules do not need custom
 302  * initcall levels. There are still some valid cases where
 303  * a driver may be needed early if built in, and does not
 304  * matter when built as a loadable module. Like bus
 305  * snooping debug drivers.
 306  */
 307 #define early_initcall(fn)              module_init(fn)
 308 #define core_initcall(fn)               module_init(fn)
 309 #define core_initcall_sync(fn)          module_init(fn)
 310 #define postcore_initcall(fn)           module_init(fn)
 311 #define postcore_initcall_sync(fn)      module_init(fn)
 312 #define arch_initcall(fn)               module_init(fn)
 313 #define subsys_initcall(fn)             module_init(fn)
 314 #define subsys_initcall_sync(fn)        module_init(fn)
 315 #define fs_initcall(fn)                 module_init(fn)
 316 #define fs_initcall_sync(fn)            module_init(fn)
 317 #define rootfs_initcall(fn)             module_init(fn)
 318 #define device_initcall(fn)             module_init(fn)
 319 #define device_initcall_sync(fn)        module_init(fn)
 320 #define late_initcall(fn)               module_init(fn)
 321 #define late_initcall_sync(fn)          module_init(fn)
 322
 323 #define console_initcall(fn)            module_init(fn)
 324 #define security_initcall(fn)           module_init(fn)
 325
 326 /* Each module must use one module_init(). */
 327 #define module_init(initfn)                                     \
 328         static inline initcall_t __inittest(void)               \
 329         { return initfn; }                                      \
 330         int init_module(void) __attribute__((alias(#initfn)));
 331
 332 /* This is only required if you want to be unloadable. */
 333 #define module_exit(exitfn)                                     \
 334         static inline exitcall_t __exittest(void)               \
 335         { return exitfn; }                                      \
 336         void cleanup_module(void) __attribute__((alias(#exitfn)));
 337
 338 #define __setup_param(str, unique_id, fn)       /* nothing */
 339 #define __setup(str, func)                      /* nothing */
 340 #endif
 341
 342 /* Data marked not to be saved by software suspend */
 343 #define __nosavedata __section(.data..nosave)
 344
 345 /* This means "can be init if no module support, otherwise module load
 346    may call it." */
 347 #ifdef CONFIG_MODULES
 348 #define __init_or_module
 349 #define __initdata_or_module
 350 #define __initconst_or_module
 351 #define __INIT_OR_MODULE        .text
 352 #define __INITDATA_OR_MODULE    .data
 353 #define __INITRODATA_OR_MODULE  .section ".rodata","a",%progbits
 354 #else
 355 #define __init_or_module __init
 356 #define __initdata_or_module __initdata
 357 #define __initconst_or_module __initconst
 358 #define __INIT_OR_MODULE __INIT
 359 #define __INITDATA_OR_MODULE __INITDATA
 360 #define __INITRODATA_OR_MODULE __INITRODATA
 361 #endif /*CONFIG_MODULES*/
 362
 363 #ifdef MODULE
 364 #define __exit_p(x) x
 365 #else
 366 #define __exit_p(x) NULL
 367 #endif
 368
 369 #endif /* _LINUX_INIT_H */