include/linux/init.h

   1 #ifndef _LINUX_INIT_H
   2 #define _LINUX_INIT_H
   3
   4 #include <linux/compiler.h>
   5 #include <linux/section-names.h>
   6 #include <linux/stringify.h>
   7
   8 /* These macros are used to mark some functions or
   9  * initialized data (doesn't apply to uninitialized data)
  10  * as `initialization' functions. The kernel can take this
  11  * as hint that the function is used only during the initialization
  12  * phase and free up used memory resources after
  13  *
  14  * Usage:
  15  * For functions:
  16  *
  17  * You should add __init immediately before the function name, like:
  18  *
  19  * static void __init initme(int x, int y)
  20  * {
  21  *    extern int z; z = x * y;
  22  * }
  23  *
  24  * If the function has a prototype somewhere, you can also add
  25  * __init between closing brace of the prototype and semicolon:
  26  *
  27  * extern int initialize_foobar_device(int, int, int) __init;
  28  *
  29  * For initialized data:
  30  * You should insert __initdata between the variable name and equal
  31  * sign followed by value, e.g.:
  32  *
  33  * static int init_variable __initdata = 0;
  34  * static char linux_logo[] __initdata = { 0x32, 0x36, ... };
  35  *
  36  * Don't forget to initialize data not at file scope, i.e. within a function,
  37  * as gcc otherwise puts the data into the bss section and not into the init
  38  * section.
  39  *
  40  * Also note, that this data cannot be "const".
  41  */
  42
  43 /* These are for everybody (although not all archs will actually
  44    discard it in modules) */
  45 #define __init          __section(.init.text) __cold notrace
  46 #define __initdata      __section(.init.data)
  47 #define __initconst     __section(.init.rodata)
  48 #define __exitdata      __section(.exit.data)
  49 #define __exit_call     __used __section(.exitcall.exit)
  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  * The following markers are used for the cases where the reference to
  58  * the *init / *exit section (code or data) is valid and will teach
  59  * modpost not to issue a warning.
  60  * The markers follow same syntax rules as __init / __initdata. */
  61 #define __ref            __section(.ref.text) noinline
  62 #define __refdata        __section(.ref.data)
  63 #define __refconst       __section(.ref.rodata)
  64
  65 /* compatibility defines */
  66 #define __init_refok     __ref
  67 #define __initdata_refok __refdata
  68 #define __exit_refok     __ref
  69
  70
  71 #ifdef MODULE
  72 #define __exitused
  73 #else
  74 #define __exitused  __used
  75 #endif
  76
  77 #define __exit          __section(.exit.text) __exitused __cold
  78
  79 /* Used for HOTPLUG */
  80 #define __devinit        __section(.devinit.text) __cold
  81 #define __devinitdata    __section(.devinit.data)
  82 #define __devinitconst   __section(.devinit.rodata)
  83 #define __devexit        __section(.devexit.text) __exitused __cold
  84 #define __devexitdata    __section(.devexit.data)
  85 #define __devexitconst   __section(.devexit.rodata)
  86
  87 /* Used for HOTPLUG_CPU */
  88 #define __cpuinit        __section(.cpuinit.text) __cold
  89 #define __cpuinitdata    __section(.cpuinit.data)
  90 #define __cpuinitconst   __section(.cpuinit.rodata)
  91 #define __cpuexit        __section(.cpuexit.text) __exitused __cold
  92 #define __cpuexitdata    __section(.cpuexit.data)
  93 #define __cpuexitconst   __section(.cpuexit.rodata)
  94
  95 /* Used for MEMORY_HOTPLUG */
  96 #define __meminit        __section(.meminit.text) __cold
  97 #define __meminitdata    __section(.meminit.data)
  98 #define __meminitconst   __section(.meminit.rodata)
  99 #define __memexit        __section(.memexit.text) __exitused __cold
 100 #define __memexitdata    __section(.memexit.data)
 101 #define __memexitconst   __section(.memexit.rodata)
 102
 103 /* For assembly routines */
 104 #define __HEAD          .section        __stringify(HEAD_TEXT_SECTION),"ax"
 105 #define __INIT          .section        ".init.text","ax"
 106 #define __FINIT         .previous
 107
 108 #define __INITDATA      .section        ".init.data","aw"
 109 #define __INITRODATA    .section        ".init.rodata","a"
 110 #define __FINITDATA     .previous
 111
 112 #define __DEVINIT        .section       ".devinit.text", "ax"
 113 #define __DEVINITDATA    .section       ".devinit.data", "aw"
 114 #define __DEVINITRODATA  .section       ".devinit.rodata", "a"
 115
 116 #define __CPUINIT        .section       ".cpuinit.text", "ax"
 117 #define __CPUINITDATA    .section       ".cpuinit.data", "aw"
 118 #define __CPUINITRODATA  .section       ".cpuinit.rodata", "a"
 119
 120 #define __MEMINIT        .section       ".meminit.text", "ax"
 121 #define __MEMINITDATA    .section       ".meminit.data", "aw"
 122 #define __MEMINITRODATA  .section       ".meminit.rodata", "a"
 123
 124 /* silence warnings when references are OK */
 125 #define __REF            .section       ".ref.text", "ax"
 126 #define __REFDATA        .section       ".ref.data", "aw"
 127 #define __REFCONST       .section       ".ref.rodata", "a"
 128
 129 #ifndef __ASSEMBLY__
 130 /*
 131  * Used for initialization calls..
 132  */
 133 typedef int (*initcall_t)(void);
 134 typedef void (*exitcall_t)(void);
 135
 136 extern initcall_t __con_initcall_start[], __con_initcall_end[];
 137 extern initcall_t __security_initcall_start[], __security_initcall_end[];
 138
 139 /* Defined in init/main.c */
 140 extern int do_one_initcall(initcall_t fn);
 141 extern char __initdata boot_command_line[];
 142 extern char *saved_command_line;
 143 extern unsigned int reset_devices;
 144
 145 /* used by init/main.c */
 146 void setup_arch(char **);
 147 void prepare_namespace(void);
 148
 149 extern void (*late_time_init)(void);
 150
 151 #endif
 152
 153 #ifndef MODULE
 154
 155 #ifndef __ASSEMBLY__
 156
 157 /* initcalls are now grouped by functionality into separate
 158  * subsections. Ordering inside the subsections is determined
 159  * by link order.
 160  * For backwards compatibility, initcall() puts the call in
 161  * the device init subsection.
 162  *
 163  * The `id' arg to __define_initcall() is needed so that multiple initcalls
 164  * can point at the same handler without causing duplicate-symbol build errors.
 165  */
 166
 167 #define __define_initcall(level,fn,id) \
 168         static initcall_t __initcall_##fn##id __used \
 169         __attribute__((__section__(".initcall" level ".init"))) = fn
 170
 171 /*
 172  * Early initcalls run before initializing SMP.
 173  *
 174  * Only for built-in code, not modules.
 175  */
 176 #define early_initcall(fn)              __define_initcall("early",fn,early)
 177
 178 /*
 179  * A "pure" initcall has no dependencies on anything else, and purely
 180  * initializes variables that couldn't be statically initialized.
 181  *
 182  * This only exists for built-in code, not for modules.
 183  */
 184 #define pure_initcall(fn)               __define_initcall("0",fn,0)
 185
 186 #define core_initcall(fn)               __define_initcall("1",fn,1)
 187 #define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
 188 #define postcore_initcall(fn)           __define_initcall("2",fn,2)
 189 #define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
 190 #define arch_initcall(fn)               __define_initcall("3",fn,3)
 191 #define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
 192 #define subsys_initcall(fn)             __define_initcall("4",fn,4)
 193 #define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
 194 #define fs_initcall(fn)                 __define_initcall("5",fn,5)
 195 #define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
 196 #define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
 197 #define device_initcall(fn)             __define_initcall("6",fn,6)
 198 #define device_initcall_sync(fn)        __define_initcall("6s",fn,6s)
 199 #define late_initcall(fn)               __define_initcall("7",fn,7)
 200 #define late_initcall_sync(fn)          __define_initcall("7s",fn,7s)
 201
 202 #define __initcall(fn) device_initcall(fn)
 203
 204 #define __exitcall(fn) \
 205         static exitcall_t __exitcall_##fn __exit_call = fn
 206
 207 #define console_initcall(fn) \
 208         static initcall_t __initcall_##fn \
 209         __used __section(.con_initcall.init) = fn
 210
 211 #define security_initcall(fn) \
 212         static initcall_t __initcall_##fn \
 213         __used __section(.security_initcall.init) = fn
 214
 215 struct obs_kernel_param {
 216         const char *str;
 217         int (*setup_func)(char *);
 218         int early;
 219 };
 220
 221 /*
 222  * Only for really core code.  See moduleparam.h for the normal way.
 223  *
 224  * Force the alignment so the compiler doesn't space elements of the
 225  * obs_kernel_param "array" too far apart in .init.setup.
 226  */
 227 #define __setup_param(str, unique_id, fn, early)                        \
 228         static char __setup_str_##unique_id[] __initdata __aligned(1) = str; \
 229         static struct obs_kernel_param __setup_##unique_id      \
 230                 __used __section(.init.setup)                   \
 231                 __attribute__((aligned((sizeof(long)))))        \
 232                 = { __setup_str_##unique_id, fn, early }
 233
 234 #define __setup(str, fn)                                        \
 235         __setup_param(str, fn, fn, 0)
 236
 237 /* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 238  * returns non-zero. */
 239 #define early_param(str, fn)                                    \
 240         __setup_param(str, fn, fn, 1)
 241
 242 /* Relies on boot_command_line being set */
 243 void __init parse_early_param(void);
 244 void __init parse_early_options(char *cmdline);
 245 #endif /* __ASSEMBLY__ */
 246
 247 /**
 248  * module_init() - driver initialization entry point
 249  * @x: function to be run at kernel boot time or module insertion
 250  *
 251  * module_init() will either be called during do_initcalls() (if
 252  * builtin) or at module insertion time (if a module).  There can only
 253  * be one per module.
 254  */
 255 #define module_init(x)  __initcall(x);
 256
 257 /**
 258  * module_exit() - driver exit entry point
 259  * @x: function to be run when driver is removed
 260  *
 261  * module_exit() will wrap the driver clean-up code
 262  * with cleanup_module() when used with rmmod when
 263  * the driver is a module.  If the driver is statically
 264  * compiled into the kernel, module_exit() has no effect.
 265  * There can only be one per module.
 266  */
 267 #define module_exit(x)  __exitcall(x);
 268
 269 #else /* MODULE */
 270
 271 /* Don't use these in modules, but some people do... */
 272 #define core_initcall(fn)               module_init(fn)
 273 #define postcore_initcall(fn)           module_init(fn)
 274 #define arch_initcall(fn)               module_init(fn)
 275 #define subsys_initcall(fn)             module_init(fn)
 276 #define fs_initcall(fn)                 module_init(fn)
 277 #define device_initcall(fn)             module_init(fn)
 278 #define late_initcall(fn)               module_init(fn)
 279
 280 #define security_initcall(fn)           module_init(fn)
 281
 282 /* Each module must use one module_init(). */
 283 #define module_init(initfn)                                     \
 284         static inline initcall_t __inittest(void)               \
 285         { return initfn; }                                      \
 286         int init_module(void) __attribute__((alias(#initfn)));
 287
 288 /* This is only required if you want to be unloadable. */
 289 #define module_exit(exitfn)                                     \
 290         static inline exitcall_t __exittest(void)               \
 291         { return exitfn; }                                      \
 292         void cleanup_module(void) __attribute__((alias(#exitfn)));
 293
 294 #define __setup_param(str, unique_id, fn)       /* nothing */
 295 #define __setup(str, func)                      /* nothing */
 296 #endif
 297
 298 /* Data marked not to be saved by software suspend */
 299 #define __nosavedata __section(.data.nosave)
 300
 301 /* This means "can be init if no module support, otherwise module load
 302    may call it." */
 303 #ifdef CONFIG_MODULES
 304 #define __init_or_module
 305 #define __initdata_or_module
 306 #else
 307 #define __init_or_module __init
 308 #define __initdata_or_module __initdata
 309 #endif /*CONFIG_MODULES*/
 310
 311 /* Functions marked as __devexit may be discarded at kernel link time, depending
 312    on config options.  Newer versions of binutils detect references from
 313    retained sections to discarded sections and flag an error.  Pointers to
 314    __devexit functions must use __devexit_p(function_name), the wrapper will
 315    insert either the function_name or NULL, depending on the config options.
 316  */
 317 #if defined(MODULE) || defined(CONFIG_HOTPLUG)
 318 #define __devexit_p(x) x
 319 #else
 320 #define __devexit_p(x) NULL
 321 #endif
 322
 323 #ifdef MODULE
 324 #define __exit_p(x) x
 325 #else
 326 #define __exit_p(x) NULL
 327 #endif
 328
 329 #endif /* _LINUX_INIT_H */