projects/linux·blob v3.15 · refs

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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 */
135typedef int (*initcall_t)(void);
136typedef void (*exitcall_t)(void);
137
138extern initcall_t __con_initcall_start[], __con_initcall_end[];
139extern initcall_t __security_initcall_start[], __security_initcall_end[];
140
141/* Used for contructor calls. */
142typedef void (*ctor_fn_t)(void);
143
144/* Defined in init/main.c */
145extern int do_one_initcall(initcall_t fn);
146extern char __initdata boot_command_line[];
147extern char *saved_command_line;
148extern unsigned int reset_devices;
149
150/* used by init/main.c */
151void setup_arch(char **);
152void prepare_namespace(void);
153void __init load_default_modules(void);
154int __init init_rootfs(void);
155
156extern void (*late_time_init)(void);
157
158extern 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
243struct 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 */
272void __init parse_early_param(void);
273void __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/* Don't use these in loadable modules, but some people do... */
301#define early_initcall(fn) module_init(fn)
302#define core_initcall(fn) module_init(fn)
303#define postcore_initcall(fn) module_init(fn)
304#define arch_initcall(fn) module_init(fn)
305#define subsys_initcall(fn) module_init(fn)
306#define fs_initcall(fn) module_init(fn)
307#define rootfs_initcall(fn) module_init(fn)
308#define device_initcall(fn) module_init(fn)
309#define late_initcall(fn) module_init(fn)
310
311#define console_initcall(fn) module_init(fn)
312#define security_initcall(fn) module_init(fn)
313
314/* Each module must use one module_init(). */
315#define module_init(initfn) \
316 static inline initcall_t __inittest(void) \
317 { return initfn; } \
318 int init_module(void) __attribute__((alias(#initfn)));
319
320/* This is only required if you want to be unloadable. */
321#define module_exit(exitfn) \
322 static inline exitcall_t __exittest(void) \
323 { return exitfn; } \
324 void cleanup_module(void) __attribute__((alias(#exitfn)));
325
326#define __setup_param(str, unique_id, fn) /* nothing */
327#define __setup(str, func) /* nothing */
328#endif
329
330/* Data marked not to be saved by software suspend */
331#define __nosavedata __section(.data..nosave)
332
333/* This means "can be init if no module support, otherwise module load
334 may call it." */
335#ifdef CONFIG_MODULES
336#define __init_or_module
337#define __initdata_or_module
338#define __initconst_or_module
339#define __INIT_OR_MODULE .text
340#define __INITDATA_OR_MODULE .data
341#define __INITRODATA_OR_MODULE .section ".rodata","a",%progbits
342#else
343#define __init_or_module __init
344#define __initdata_or_module __initdata
345#define __initconst_or_module __initconst
346#define __INIT_OR_MODULE __INIT
347#define __INITDATA_OR_MODULE __INITDATA
348#define __INITRODATA_OR_MODULE __INITRODATA
349#endif /*CONFIG_MODULES*/
350
351#ifdef MODULE
352#define __exit_p(x) x
353#else
354#define __exit_p(x) NULL
355#endif
356
357#endif /* _LINUX_INIT_H */