1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_INIT_H
3 #define _LINUX_INIT_H
4
5 #include <linux/build_bug.h>
6 #include <linux/compiler.h>
7 #include <linux/stringify.h>
8 #include <linux/types.h>
9
10 /* Built-in __init functions needn't be compiled with retpoline */
11 #if defined(__noretpoline) && !defined(MODULE)
12 #define __noinitretpoline __noretpoline
13 #else
14 #define __noinitretpoline
15 #endif
16
17 /* These macros are used to mark some functions or
18 * initialized data (doesn't apply to uninitialized data)
19 * as `initialization' functions. The kernel can take this
20 * as hint that the function is used only during the initialization
21 * phase and free up used memory resources after
22 *
23 * Usage:
24 * For functions:
25 *
26 * You should add __init immediately before the function name, like:
27 *
28 * static void __init initme(int x, int y)
29 * {
30 * extern int z; z = x * y;
31 * }
32 *
33 * If the function has a prototype somewhere, you can also add
34 * __init between closing brace of the prototype and semicolon:
35 *
36 * extern int initialize_foobar_device(int, int, int) __init;
37 *
38 * For initialized data:
39 * You should insert __initdata or __initconst between the variable name
40 * and equal sign followed by value, e.g.:
41 *
42 * static int init_variable __initdata = 0;
43 * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
44 *
45 * Don't forget to initialize data not at file scope, i.e. within a function,
46 * as gcc otherwise puts the data into the bss section and not into the init
47 * section.
48 */
49
50 /* These are for everybody (although not all archs will actually
51 discard it in modules) */
52 #define __init __section(".init.text") __cold __latent_entropy __noinitretpoline
53 #define __initdata __section(".init.data")
54 #define __initconst __section(".init.rodata")
55 #define __exitdata __section(".exit.data")
56 #define __exit_call __used __section(".exitcall.exit")
57
58 /*
59 * modpost check for section mismatches during the kernel build.
60 * A section mismatch happens when there are references from a
61 * code or data section to an init section (both code or data).
62 * The init sections are (for most archs) discarded by the kernel
63 * when early init has completed so all such references are potential bugs.
64 * For exit sections the same issue exists.
65 *
66 * The following markers are used for the cases where the reference to
67 * the *init / *exit section (code or data) is valid and will teach
68 * modpost not to issue a warning. Intended semantics is that a code or
69 * data tagged __ref* can reference code or data from init section without
70 * producing a warning (of course, no warning does not mean code is
71 * correct, so optimally document why the __ref is needed and why it's OK).
72 *
73 * The markers follow same syntax rules as __init / __initdata.
74 */
75 #define __ref __section(".ref.text") noinline
76 #define __refdata __section(".ref.data")
77 #define __refconst __section(".ref.rodata")
78
79 #ifdef MODULE
80 #define __exitused
81 #else
82 #define __exitused __used
83 #endif
84
85 #define __exit __section(".exit.text") __exitused __cold notrace
86
87 #ifdef CONFIG_MEMORY_HOTPLUG
88 #define __meminit
89 #define __meminitdata
90 #define __meminitconst
91 #else
92 #define __meminit __init
93 #define __meminitdata __initdata
94 #define __meminitconst __initconst
95 #endif
96
97 /* For assembly routines */
98 #define __HEAD .section ".head.text","ax"
99 #define __INIT .section ".init.text","ax"
100 #define __FINIT .previous
101
102 #define __INITDATA .section ".init.data","aw",%progbits
103 #define __INITRODATA .section ".init.rodata","a",%progbits
104 #define __FINITDATA .previous
105
106 /* silence warnings when references are OK */
107 #define __REF .section ".ref.text", "ax"
108 #define __REFDATA .section ".ref.data", "aw"
109 #define __REFCONST .section ".ref.rodata", "a"
110
111 #ifndef __ASSEMBLY__
112 /*
113 * Used for initialization calls..
114 */
115 typedef int (*initcall_t)(void);
116 typedef void (*exitcall_t)(void);
117
118 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
119 typedef int initcall_entry_t;
120
initcall_from_entry(initcall_entry_t * entry)121 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
122 {
123 return offset_to_ptr(entry);
124 }
125 #else
126 typedef initcall_t initcall_entry_t;
127
initcall_from_entry(initcall_entry_t * entry)128 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
129 {
130 return *entry;
131 }
132 #endif
133
134 extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
135
136 /* Used for constructor calls. */
137 typedef void (*ctor_fn_t)(void);
138
139 struct file_system_type;
140
141 /* Defined in init/main.c */
142 extern int do_one_initcall(initcall_t fn);
143 extern char __initdata boot_command_line[];
144 extern char *saved_command_line;
145 extern unsigned int saved_command_line_len;
146 extern unsigned int reset_devices;
147
148 /* used by init/main.c */
149 void setup_arch(char **);
150 void prepare_namespace(void);
151 void __init init_rootfs(void);
152
153 void init_IRQ(void);
154 void time_init(void);
155 void poking_init(void);
156 void pgtable_cache_init(void);
157
158 extern initcall_entry_t __initcall_start[];
159 extern initcall_entry_t __initcall0_start[];
160 extern initcall_entry_t __initcall1_start[];
161 extern initcall_entry_t __initcall2_start[];
162 extern initcall_entry_t __initcall3_start[];
163 extern initcall_entry_t __initcall4_start[];
164 extern initcall_entry_t __initcall5_start[];
165 extern initcall_entry_t __initcall6_start[];
166 extern initcall_entry_t __initcall7_start[];
167 extern initcall_entry_t __initcall_end[];
168
169 extern struct file_system_type rootfs_fs_type;
170
171 extern bool rodata_enabled;
172 void mark_rodata_ro(void);
173
174 extern void (*late_time_init)(void);
175
176 extern bool initcall_debug;
177
178 #ifdef MODULE
179 extern struct module __this_module;
180 #define THIS_MODULE (&__this_module)
181 #else
182 #define THIS_MODULE ((struct module *)0)
183 #endif
184
185 #endif
186
187 #ifndef MODULE
188
189 #ifndef __ASSEMBLY__
190
191 /*
192 * initcalls are now grouped by functionality into separate
193 * subsections. Ordering inside the subsections is determined
194 * by link order.
195 * For backwards compatibility, initcall() puts the call in
196 * the device init subsection.
197 *
198 * The `id' arg to __define_initcall() is needed so that multiple initcalls
199 * can point at the same handler without causing duplicate-symbol build errors.
200 *
201 * Initcalls are run by placing pointers in initcall sections that the
202 * kernel iterates at runtime. The linker can do dead code / data elimination
203 * and remove that completely, so the initcall sections have to be marked
204 * as KEEP() in the linker script.
205 */
206
207 /* Format: <modname>__<counter>_<line>_<fn> */
208 #define __initcall_id(fn) \
209 __PASTE(__KBUILD_MODNAME, \
210 __PASTE(__, \
211 __PASTE(__COUNTER__, \
212 __PASTE(_, \
213 __PASTE(__LINE__, \
214 __PASTE(_, fn))))))
215
216 /* Format: __<prefix>__<iid><id> */
217 #define __initcall_name(prefix, __iid, id) \
218 __PASTE(__, \
219 __PASTE(prefix, \
220 __PASTE(__, \
221 __PASTE(__iid, id))))
222
223 #ifdef CONFIG_LTO_CLANG
224 /*
225 * With LTO, the compiler doesn't necessarily obey link order for
226 * initcalls. In order to preserve the correct order, we add each
227 * variable into its own section and generate a linker script (in
228 * scripts/link-vmlinux.sh) to specify the order of the sections.
229 */
230 #define __initcall_section(__sec, __iid) \
231 #__sec ".init.." #__iid
232
233 /*
234 * With LTO, the compiler can rename static functions to avoid
235 * global naming collisions. We use a global stub function for
236 * initcalls to create a stable symbol name whose address can be
237 * taken in inline assembly when PREL32 relocations are used.
238 */
239 #define __initcall_stub(fn, __iid, id) \
240 __initcall_name(initstub, __iid, id)
241
242 #define __define_initcall_stub(__stub, fn) \
243 int __init __stub(void); \
244 int __init __stub(void) \
245 { \
246 return fn(); \
247 } \
248 __ADDRESSABLE(__stub)
249 #else
250 #define __initcall_section(__sec, __iid) \
251 #__sec ".init"
252
253 #define __initcall_stub(fn, __iid, id) fn
254
255 #define __define_initcall_stub(__stub, fn) \
256 __ADDRESSABLE(fn)
257 #endif
258
259 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
260 #define ____define_initcall(fn, __stub, __name, __sec) \
261 __define_initcall_stub(__stub, fn) \
262 asm(".section \"" __sec "\", \"a\" \n" \
263 __stringify(__name) ": \n" \
264 ".long " __stringify(__stub) " - . \n" \
265 ".previous \n"); \
266 static_assert(__same_type(initcall_t, &fn));
267 #else
268 #define ____define_initcall(fn, __unused, __name, __sec) \
269 static initcall_t __name __used \
270 __attribute__((__section__(__sec))) = fn;
271 #endif
272
273 #define __unique_initcall(fn, id, __sec, __iid) \
274 ____define_initcall(fn, \
275 __initcall_stub(fn, __iid, id), \
276 __initcall_name(initcall, __iid, id), \
277 __initcall_section(__sec, __iid))
278
279 #define ___define_initcall(fn, id, __sec) \
280 __unique_initcall(fn, id, __sec, __initcall_id(fn))
281
282 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
283
284 /*
285 * Early initcalls run before initializing SMP.
286 *
287 * Only for built-in code, not modules.
288 */
289 #define early_initcall(fn) __define_initcall(fn, early)
290
291 /*
292 * A "pure" initcall has no dependencies on anything else, and purely
293 * initializes variables that couldn't be statically initialized.
294 *
295 * This only exists for built-in code, not for modules.
296 * Keep main.c:initcall_level_names[] in sync.
297 */
298 #define pure_initcall(fn) __define_initcall(fn, 0)
299
300 #define core_initcall(fn) __define_initcall(fn, 1)
301 #define core_initcall_sync(fn) __define_initcall(fn, 1s)
302 #define postcore_initcall(fn) __define_initcall(fn, 2)
303 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s)
304 #define arch_initcall(fn) __define_initcall(fn, 3)
305 #define arch_initcall_sync(fn) __define_initcall(fn, 3s)
306 #define subsys_initcall(fn) __define_initcall(fn, 4)
307 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s)
308 #define fs_initcall(fn) __define_initcall(fn, 5)
309 #define fs_initcall_sync(fn) __define_initcall(fn, 5s)
310 #define rootfs_initcall(fn) __define_initcall(fn, rootfs)
311 #define device_initcall(fn) __define_initcall(fn, 6)
312 #define device_initcall_sync(fn) __define_initcall(fn, 6s)
313 #define late_initcall(fn) __define_initcall(fn, 7)
314 #define late_initcall_sync(fn) __define_initcall(fn, 7s)
315
316 #define __initcall(fn) device_initcall(fn)
317
318 #define __exitcall(fn) \
319 static exitcall_t __exitcall_##fn __exit_call = fn
320
321 #define console_initcall(fn) ___define_initcall(fn, con, .con_initcall)
322
323 struct obs_kernel_param {
324 const char *str;
325 int (*setup_func)(char *);
326 int early;
327 };
328
329 extern const struct obs_kernel_param __setup_start[], __setup_end[];
330
331 /*
332 * Only for really core code. See moduleparam.h for the normal way.
333 *
334 * Force the alignment so the compiler doesn't space elements of the
335 * obs_kernel_param "array" too far apart in .init.setup.
336 */
337 #define __setup_param(str, unique_id, fn, early) \
338 static const char __setup_str_##unique_id[] __initconst \
339 __aligned(1) = str; \
340 static struct obs_kernel_param __setup_##unique_id \
341 __used __section(".init.setup") \
342 __aligned(__alignof__(struct obs_kernel_param)) \
343 = { __setup_str_##unique_id, fn, early }
344
345 /*
346 * NOTE: __setup functions return values:
347 * @fn returns 1 (or non-zero) if the option argument is "handled"
348 * and returns 0 if the option argument is "not handled".
349 */
350 #define __setup(str, fn) \
351 __setup_param(str, fn, fn, 0)
352
353 /*
354 * NOTE: @fn is as per module_param, not __setup!
355 * I.e., @fn returns 0 for no error or non-zero for error
356 * (possibly @fn returns a -errno value, but it does not matter).
357 * Emits warning if @fn returns non-zero.
358 */
359 #define early_param(str, fn) \
360 __setup_param(str, fn, fn, 1)
361
362 #define early_param_on_off(str_on, str_off, var, config) \
363 \
364 int var = IS_ENABLED(config); \
365 \
366 static int __init parse_##var##_on(char *arg) \
367 { \
368 var = 1; \
369 return 0; \
370 } \
371 early_param(str_on, parse_##var##_on); \
372 \
373 static int __init parse_##var##_off(char *arg) \
374 { \
375 var = 0; \
376 return 0; \
377 } \
378 early_param(str_off, parse_##var##_off)
379
380 /* Relies on boot_command_line being set */
381 void __init parse_early_param(void);
382 void __init parse_early_options(char *cmdline);
383 #endif /* __ASSEMBLY__ */
384
385 #else /* MODULE */
386
387 #define __setup_param(str, unique_id, fn) /* nothing */
388 #define __setup(str, func) /* nothing */
389 #endif
390
391 /* Data marked not to be saved by software suspend */
392 #define __nosavedata __section(".data..nosave")
393
394 #ifdef MODULE
395 #define __exit_p(x) x
396 #else
397 #define __exit_p(x) NULL
398 #endif
399
400 #endif /* _LINUX_INIT_H */
401