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Linux/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 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  */
150 typedef int (*initcall_t)(void);
151 typedef void (*exitcall_t)(void);
152 
153 extern initcall_t __con_initcall_start[], __con_initcall_end[];
154 extern initcall_t __security_initcall_start[], __security_initcall_end[];
155 
156 /* Used for contructor calls. */
157 typedef void (*ctor_fn_t)(void);
158 
159 /* Defined in init/main.c */
160 extern int do_one_initcall(initcall_t fn);
161 extern char __initdata boot_command_line[];
162 extern char *saved_command_line;
163 extern unsigned int reset_devices;
164 
165 /* used by init/main.c */
166 void setup_arch(char **);
167 void prepare_namespace(void);
168 
169 extern void (*late_time_init)(void);
170 
171 extern 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("",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 
238 struct 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 */
267 void __init parse_early_param(void);
268 void __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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