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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 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 */
370 

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