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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 /* initcalls are now grouped by functionality into separate 
167  * subsections. Ordering inside the subsections is determined
168  * by link order. 
169  * For backwards compatibility, initcall() puts the call in 
170  * the device init subsection.
171  *
172  * The `id' arg to __define_initcall() is needed so that multiple initcalls
173  * can point at the same handler without causing duplicate-symbol build errors.
174  */
175 
176 #define __define_initcall(fn, id) \
177         static initcall_t __initcall_##fn##id __used \
178         __attribute__((__section__(".initcall" #id ".init"))) = fn
179 
180 /*
181  * Early initcalls run before initializing SMP.
182  *
183  * Only for built-in code, not modules.
184  */
185 #define early_initcall(fn)              __define_initcall(fn, early)
186 
187 /*
188  * A "pure" initcall has no dependencies on anything else, and purely
189  * initializes variables that couldn't be statically initialized.
190  *
191  * This only exists for built-in code, not for modules.
192  * Keep main.c:initcall_level_names[] in sync.
193  */
194 #define pure_initcall(fn)               __define_initcall(fn, 0)
195 
196 #define core_initcall(fn)               __define_initcall(fn, 1)
197 #define core_initcall_sync(fn)          __define_initcall(fn, 1s)
198 #define postcore_initcall(fn)           __define_initcall(fn, 2)
199 #define postcore_initcall_sync(fn)      __define_initcall(fn, 2s)
200 #define arch_initcall(fn)               __define_initcall(fn, 3)
201 #define arch_initcall_sync(fn)          __define_initcall(fn, 3s)
202 #define subsys_initcall(fn)             __define_initcall(fn, 4)
203 #define subsys_initcall_sync(fn)        __define_initcall(fn, 4s)
204 #define fs_initcall(fn)                 __define_initcall(fn, 5)
205 #define fs_initcall_sync(fn)            __define_initcall(fn, 5s)
206 #define rootfs_initcall(fn)             __define_initcall(fn, rootfs)
207 #define device_initcall(fn)             __define_initcall(fn, 6)
208 #define device_initcall_sync(fn)        __define_initcall(fn, 6s)
209 #define late_initcall(fn)               __define_initcall(fn, 7)
210 #define late_initcall_sync(fn)          __define_initcall(fn, 7s)
211 
212 #define __initcall(fn) device_initcall(fn)
213 
214 #define __exitcall(fn) \
215         static exitcall_t __exitcall_##fn __exit_call = fn
216 
217 #define console_initcall(fn) \
218         static initcall_t __initcall_##fn \
219         __used __section(.con_initcall.init) = fn
220 
221 #define security_initcall(fn) \
222         static initcall_t __initcall_##fn \
223         __used __section(.security_initcall.init) = fn
224 
225 struct obs_kernel_param {
226         const char *str;
227         int (*setup_func)(char *);
228         int early;
229 };
230 
231 /*
232  * Only for really core code.  See moduleparam.h for the normal way.
233  *
234  * Force the alignment so the compiler doesn't space elements of the
235  * obs_kernel_param "array" too far apart in .init.setup.
236  */
237 #define __setup_param(str, unique_id, fn, early)                        \
238         static const char __setup_str_##unique_id[] __initconst \
239                 __aligned(1) = str; \
240         static struct obs_kernel_param __setup_##unique_id      \
241                 __used __section(.init.setup)                   \
242                 __attribute__((aligned((sizeof(long)))))        \
243                 = { __setup_str_##unique_id, fn, early }
244 
245 #define __setup(str, fn)                                        \
246         __setup_param(str, fn, fn, 0)
247 
248 /* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
249  * returns non-zero. */
250 #define early_param(str, fn)                                    \
251         __setup_param(str, fn, fn, 1)
252 
253 /* Relies on boot_command_line being set */
254 void __init parse_early_param(void);
255 void __init parse_early_options(char *cmdline);
256 #endif /* __ASSEMBLY__ */
257 
258 /**
259  * module_init() - driver initialization entry point
260  * @x: function to be run at kernel boot time or module insertion
261  * 
262  * module_init() will either be called during do_initcalls() (if
263  * builtin) or at module insertion time (if a module).  There can only
264  * be one per module.
265  */
266 #define module_init(x)  __initcall(x);
267 
268 /**
269  * module_exit() - driver exit entry point
270  * @x: function to be run when driver is removed
271  * 
272  * module_exit() will wrap the driver clean-up code
273  * with cleanup_module() when used with rmmod when
274  * the driver is a module.  If the driver is statically
275  * compiled into the kernel, module_exit() has no effect.
276  * There can only be one per module.
277  */
278 #define module_exit(x)  __exitcall(x);
279 
280 #else /* MODULE */
281 
282 /* Don't use these in loadable modules, but some people do... */
283 #define early_initcall(fn)              module_init(fn)
284 #define core_initcall(fn)               module_init(fn)
285 #define postcore_initcall(fn)           module_init(fn)
286 #define arch_initcall(fn)               module_init(fn)
287 #define subsys_initcall(fn)             module_init(fn)
288 #define fs_initcall(fn)                 module_init(fn)
289 #define rootfs_initcall(fn)             module_init(fn)
290 #define device_initcall(fn)             module_init(fn)
291 #define late_initcall(fn)               module_init(fn)
292 
293 #define console_initcall(fn)            module_init(fn)
294 #define security_initcall(fn)           module_init(fn)
295 
296 /* Each module must use one module_init(). */
297 #define module_init(initfn)                                     \
298         static inline initcall_t __inittest(void)               \
299         { return initfn; }                                      \
300         int init_module(void) __attribute__((alias(#initfn)));
301 
302 /* This is only required if you want to be unloadable. */
303 #define module_exit(exitfn)                                     \
304         static inline exitcall_t __exittest(void)               \
305         { return exitfn; }                                      \
306         void cleanup_module(void) __attribute__((alias(#exitfn)));
307 
308 #define __setup_param(str, unique_id, fn)       /* nothing */
309 #define __setup(str, func)                      /* nothing */
310 #endif
311 
312 /* Data marked not to be saved by software suspend */
313 #define __nosavedata __section(.data..nosave)
314 
315 /* This means "can be init if no module support, otherwise module load
316    may call it." */
317 #ifdef CONFIG_MODULES
318 #define __init_or_module
319 #define __initdata_or_module
320 #define __initconst_or_module
321 #define __INIT_OR_MODULE        .text
322 #define __INITDATA_OR_MODULE    .data
323 #define __INITRODATA_OR_MODULE  .section ".rodata","a",%progbits
324 #else
325 #define __init_or_module __init
326 #define __initdata_or_module __initdata
327 #define __initconst_or_module __initconst
328 #define __INIT_OR_MODULE __INIT
329 #define __INITDATA_OR_MODULE __INITDATA
330 #define __INITRODATA_OR_MODULE __INITRODATA
331 #endif /*CONFIG_MODULES*/
332 
333 #ifdef MODULE
334 #define __exit_p(x) x
335 #else
336 #define __exit_p(x) NULL
337 #endif
338 
339 #endif /* _LINUX_INIT_H */
340 

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