1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_INIT_H
3#define _LINUX_INIT_H
4
5#include <linux/compiler.h>
6#include <linux/types.h>
7
8/* Built-in __init functions needn't be compiled with retpoline */
9#if defined(__noretpoline) && !defined(MODULE)
10#define __noinitretpoline __noretpoline
11#else
12#define __noinitretpoline
13#endif
14
15/* These macros are used to mark some functions or
16 * initialized data (doesn't apply to uninitialized data)
17 * as `initialization' functions. The kernel can take this
18 * as hint that the function is used only during the initialization
19 * phase and free up used memory resources after
20 *
21 * Usage:
22 * For functions:
23 *
24 * You should add __init immediately before the function name, like:
25 *
26 * static void __init initme(int x, int y)
27 * {
28 * extern int z; z = x * y;
29 * }
30 *
31 * If the function has a prototype somewhere, you can also add
32 * __init between closing brace of the prototype and semicolon:
33 *
34 * extern int initialize_foobar_device(int, int, int) __init;
35 *
36 * For initialized data:
37 * You should insert __initdata or __initconst between the variable name
38 * and equal sign followed by value, e.g.:
39 *
40 * static int init_variable __initdata = 0;
41 * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
42 *
43 * Don't forget to initialize data not at file scope, i.e. within a function,
44 * as gcc otherwise puts the data into the bss section and not into the init
45 * section.
46 */
47
48/* These are for everybody (although not all archs will actually
49 discard it in modules) */
50#define __init __section(".init.text") __cold __latent_entropy __noinitretpoline __nocfi
51#define __initdata __section(".init.data")
52#define __initconst __section(".init.rodata")
53#define __exitdata __section(".exit.data")
54#define __exit_call __used __section(".exitcall.exit")
55
56/*
57 * modpost check for section mismatches during the kernel build.
58 * A section mismatch happens when there are references from a
59 * code or data section to an init section (both code or data).
60 * The init sections are (for most archs) discarded by the kernel
61 * when early init has completed so all such references are potential bugs.
62 * For exit sections the same issue exists.
63 *
64 * The following markers are used for the cases where the reference to
65 * the *init / *exit section (code or data) is valid and will teach
66 * modpost not to issue a warning. Intended semantics is that a code or
67 * data tagged __ref* can reference code or data from init section without
68 * producing a warning (of course, no warning does not mean code is
69 * correct, so optimally document why the __ref is needed and why it's OK).
70 *
71 * The markers follow same syntax rules as __init / __initdata.
72 */
73#define __ref __section(".ref.text") noinline
74#define __refdata __section(".ref.data")
75#define __refconst __section(".ref.rodata")
76
77#ifdef MODULE
78#define __exitused
79#else
80#define __exitused __used
81#endif
82
83#define __exit __section(".exit.text") __exitused __cold notrace
84
85/* Used for MEMORY_HOTPLUG */
86#define __meminit __section(".meminit.text") __cold notrace \
87 __latent_entropy
88#define __meminitdata __section(".meminit.data")
89#define __meminitconst __section(".meminit.rodata")
90#define __memexit __section(".memexit.text") __exitused __cold notrace
91#define __memexitdata __section(".memexit.data")
92#define __memexitconst __section(".memexit.rodata")
93
94/* For assembly routines */
95#define __HEAD .section ".head.text","ax"
96#define __INIT .section ".init.text","ax"
97#define __FINIT .previous
98
99#define __INITDATA .section ".init.data","aw",%progbits
100#define __INITRODATA .section ".init.rodata","a",%progbits
101#define __FINITDATA .previous
102
103#define __MEMINIT .section ".meminit.text", "ax"
104#define __MEMINITDATA .section ".meminit.data", "aw"
105#define __MEMINITRODATA .section ".meminit.rodata", "a"
106
107/* silence warnings when references are OK */
108#define __REF .section ".ref.text", "ax"
109#define __REFDATA .section ".ref.data", "aw"
110#define __REFCONST .section ".ref.rodata", "a"
111
112#ifndef __ASSEMBLY__
113/*
114 * Used for initialization calls..
115 */
116typedef int (*initcall_t)(void);
117typedef void (*exitcall_t)(void);
118
119#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
120typedef int initcall_entry_t;
121
122static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
123{
124 return offset_to_ptr(entry);
125}
126#else
127typedef initcall_t initcall_entry_t;
128
129static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
130{
131 return *entry;
132}
133#endif
134
135extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
136
137/* Used for contructor calls. */
138typedef void (*ctor_fn_t)(void);
139
140struct file_system_type;
141
142/* Defined in init/main.c */
143extern int do_one_initcall(initcall_t fn);
144extern char __initdata boot_command_line[];
145extern char *saved_command_line;
146extern unsigned int reset_devices;
147
148/* used by init/main.c */
149void setup_arch(char **);
150void prepare_namespace(void);
151void __init init_rootfs(void);
152extern struct file_system_type rootfs_fs_type;
153
154#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
155extern bool rodata_enabled;
156#endif
157#ifdef CONFIG_STRICT_KERNEL_RWX
158void mark_rodata_ro(void);
159#endif
160
161extern void (*late_time_init)(void);
162
163extern bool initcall_debug;
164
165#endif
166
167#ifndef MODULE
168
169#ifndef __ASSEMBLY__
170
171/*
172 * initcalls are now grouped by functionality into separate
173 * subsections. Ordering inside the subsections is determined
174 * by link order.
175 * For backwards compatibility, initcall() puts the call in
176 * the device init subsection.
177 *
178 * The `id' arg to __define_initcall() is needed so that multiple initcalls
179 * can point at the same handler without causing duplicate-symbol build errors.
180 *
181 * Initcalls are run by placing pointers in initcall sections that the
182 * kernel iterates at runtime. The linker can do dead code / data elimination
183 * and remove that completely, so the initcall sections have to be marked
184 * as KEEP() in the linker script.
185 */
186
187/* Format: <modname>__<counter>_<line>_<fn> */
188#define __initcall_id(fn) \
189 __PASTE(__KBUILD_MODNAME, \
190 __PASTE(__, \
191 __PASTE(__COUNTER__, \
192 __PASTE(_, \
193 __PASTE(__LINE__, \
194 __PASTE(_, fn))))))
195
196/* Format: __<prefix>__<iid><id> */
197#define __initcall_name(prefix, __iid, id) \
198 __PASTE(__, \
199 __PASTE(prefix, \
200 __PASTE(__, \
201 __PASTE(__iid, id))))
202
203#ifdef CONFIG_LTO_CLANG
204/*
205 * With LTO, the compiler doesn't necessarily obey link order for
206 * initcalls. In order to preserve the correct order, we add each
207 * variable into its own section and generate a linker script (in
208 * scripts/link-vmlinux.sh) to specify the order of the sections.
209 */
210#define __initcall_section(__sec, __iid) \
211 #__sec ".init.." #__iid
212
213/*
214 * With LTO, the compiler can rename static functions to avoid
215 * global naming collisions. We use a global stub function for
216 * initcalls to create a stable symbol name whose address can be
217 * taken in inline assembly when PREL32 relocations are used.
218 */
219#define __initcall_stub(fn, __iid, id) \
220 __initcall_name(initstub, __iid, id)
221
222#define __define_initcall_stub(__stub, fn) \
223 int __init __cficanonical __stub(void); \
224 int __init __cficanonical __stub(void) \
225 { \
226 return fn(); \
227 } \
228 __ADDRESSABLE(__stub)
229#else
230#define __initcall_section(__sec, __iid) \
231 #__sec ".init"
232
233#define __initcall_stub(fn, __iid, id) fn
234
235#define __define_initcall_stub(__stub, fn) \
236 __ADDRESSABLE(fn)
237#endif
238
239#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
240#define ____define_initcall(fn, __stub, __name, __sec) \
241 __define_initcall_stub(__stub, fn) \
242 asm(".section \"" __sec "\", \"a\" \n" \
243 __stringify(__name) ": \n" \
244 ".long " __stringify(__stub) " - . \n" \
245 ".previous \n"); \
246 static_assert(__same_type(initcall_t, &fn));
247#else
248#define ____define_initcall(fn, __unused, __name, __sec) \
249 static initcall_t __name __used \
250 __attribute__((__section__(__sec))) = fn;
251#endif
252
253#define __unique_initcall(fn, id, __sec, __iid) \
254 ____define_initcall(fn, \
255 __initcall_stub(fn, __iid, id), \
256 __initcall_name(initcall, __iid, id), \
257 __initcall_section(__sec, __iid))
258
259#define ___define_initcall(fn, id, __sec) \
260 __unique_initcall(fn, id, __sec, __initcall_id(fn))
261
262#define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
263
264/*
265 * Early initcalls run before initializing SMP.
266 *
267 * Only for built-in code, not modules.
268 */
269#define early_initcall(fn) __define_initcall(fn, early)
270
271/*
272 * A "pure" initcall has no dependencies on anything else, and purely
273 * initializes variables that couldn't be statically initialized.
274 *
275 * This only exists for built-in code, not for modules.
276 * Keep main.c:initcall_level_names[] in sync.
277 */
278#define pure_initcall(fn) __define_initcall(fn, 0)
279
280#define core_initcall(fn) __define_initcall(fn, 1)
281#define core_initcall_sync(fn) __define_initcall(fn, 1s)
282#define postcore_initcall(fn) __define_initcall(fn, 2)
283#define postcore_initcall_sync(fn) __define_initcall(fn, 2s)
284#define arch_initcall(fn) __define_initcall(fn, 3)
285#define arch_initcall_sync(fn) __define_initcall(fn, 3s)
286#define subsys_initcall(fn) __define_initcall(fn, 4)
287#define subsys_initcall_sync(fn) __define_initcall(fn, 4s)
288#define fs_initcall(fn) __define_initcall(fn, 5)
289#define fs_initcall_sync(fn) __define_initcall(fn, 5s)
290#define rootfs_initcall(fn) __define_initcall(fn, rootfs)
291#define device_initcall(fn) __define_initcall(fn, 6)
292#define device_initcall_sync(fn) __define_initcall(fn, 6s)
293#define late_initcall(fn) __define_initcall(fn, 7)
294#define late_initcall_sync(fn) __define_initcall(fn, 7s)
295
296#define __initcall(fn) device_initcall(fn)
297
298#define __exitcall(fn) \
299 static exitcall_t __exitcall_##fn __exit_call = fn
300
301#define console_initcall(fn) ___define_initcall(fn, con, .con_initcall)
302
303struct obs_kernel_param {
304 const char *str;
305 int (*setup_func)(char *);
306 int early;
307};
308
309/*
310 * Only for really core code. See moduleparam.h for the normal way.
311 *
312 * Force the alignment so the compiler doesn't space elements of the
313 * obs_kernel_param "array" too far apart in .init.setup.
314 */
315#define __setup_param(str, unique_id, fn, early) \
316 static const char __setup_str_##unique_id[] __initconst \
317 __aligned(1) = str; \
318 static struct obs_kernel_param __setup_##unique_id \
319 __used __section(".init.setup") \
320 __aligned(__alignof__(struct obs_kernel_param)) \
321 = { __setup_str_##unique_id, fn, early }
322
323/*
324 * NOTE: __setup functions return values:
325 * @fn returns 1 (or non-zero) if the option argument is "handled"
326 * and returns 0 if the option argument is "not handled".
327 */
328#define __setup(str, fn) \
329 __setup_param(str, fn, fn, 0)
330
331/*
332 * NOTE: @fn is as per module_param, not __setup!
333 * I.e., @fn returns 0 for no error or non-zero for error
334 * (possibly @fn returns a -errno value, but it does not matter).
335 * Emits warning if @fn returns non-zero.
336 */
337#define early_param(str, fn) \
338 __setup_param(str, fn, fn, 1)
339
340#define early_param_on_off(str_on, str_off, var, config) \
341 \
342 int var = IS_ENABLED(config); \
343 \
344 static int __init parse_##var##_on(char *arg) \
345 { \
346 var = 1; \
347 return 0; \
348 } \
349 early_param(str_on, parse_##var##_on); \
350 \
351 static int __init parse_##var##_off(char *arg) \
352 { \
353 var = 0; \
354 return 0; \
355 } \
356 early_param(str_off, parse_##var##_off)
357
358/* Relies on boot_command_line being set */
359void __init parse_early_param(void);
360void __init parse_early_options(char *cmdline);
361#endif /* __ASSEMBLY__ */
362
363#else /* MODULE */
364
365#define __setup_param(str, unique_id, fn) /* nothing */
366#define __setup(str, func) /* nothing */
367#endif
368
369/* Data marked not to be saved by software suspend */
370#define __nosavedata __section(".data..nosave")
371
372#ifdef MODULE
373#define __exit_p(x) x
374#else
375#define __exit_p(x) NULL
376#endif
377
378#endif /* _LINUX_INIT_H */
379

source code of linux/include/linux/init.h