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 \
53 __noinitretpoline \
54 __no_kstack_erase
55 #define __initdata __section(".init.data")
56 #define __initconst __section(".init.rodata")
57 #define __exitdata __section(".exit.data")
58 #define __exit_call __used __section(".exitcall.exit")
59
60 /*
61 * modpost check for section mismatches during the kernel build.
62 * A section mismatch happens when there are references from a
63 * code or data section to an init section (both code or data).
64 * The init sections are (for most archs) discarded by the kernel
65 * when early init has completed so all such references are potential bugs.
66 * For exit sections the same issue exists.
67 *
68 * The following markers are used for the cases where the reference to
69 * the *init / *exit section (code or data) is valid and will teach
70 * modpost not to issue a warning. Intended semantics is that a code or
71 * data tagged __ref* can reference code or data from init section without
72 * producing a warning (of course, no warning does not mean code is
73 * correct, so optimally document why the __ref is needed and why it's OK).
74 *
75 * The markers follow same syntax rules as __init / __initdata.
76 */
77 #define __ref __section(".ref.text") noinline
78 #define __refdata __section(".ref.data")
79 #define __refconst __section(".ref.rodata")
80
81 #ifdef MODULE
82 #define __exitused
83 #else
84 #define __exitused __used
85 #endif
86
87 #define __exit __section(".exit.text") __exitused __cold notrace
88
89 #ifdef CONFIG_MEMORY_HOTPLUG
90 #define __meminit
91 #define __meminitdata
92 #define __meminitconst
93 #else
94 #define __meminit __init
95 #define __meminitdata __initdata
96 #define __meminitconst __initconst
97 #endif
98
99 /* For assembly routines */
100 #define __HEAD .section ".head.text","ax"
101 #define __INIT .section ".init.text","ax"
102 #define __FINIT .previous
103
104 #define __INITDATA .section ".init.data","aw",%progbits
105 #define __INITRODATA .section ".init.rodata","a",%progbits
106 #define __FINITDATA .previous
107
108 /* silence warnings when references are OK */
109 #define __REF .section ".ref.text", "ax"
110 #define __REFDATA .section ".ref.data", "aw"
111 #define __REFCONST .section ".ref.rodata", "a"
112
113 #ifndef __ASSEMBLY__
114 /*
115 * Used for initialization calls..
116 */
117 typedef int (*initcall_t)(void);
118 typedef void (*exitcall_t)(void);
119
120 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
121 typedef int initcall_entry_t;
122
initcall_from_entry(initcall_entry_t * entry)123 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
124 {
125 return offset_to_ptr(entry);
126 }
127 #else
128 typedef initcall_t initcall_entry_t;
129
initcall_from_entry(initcall_entry_t * entry)130 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
131 {
132 return *entry;
133 }
134 #endif
135
136 extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
137
138 /* Used for constructor calls. */
139 typedef void (*ctor_fn_t)(void);
140
141 struct file_system_type;
142
143 /* Defined in init/main.c */
144 extern int do_one_initcall(initcall_t fn);
145 extern char __initdata boot_command_line[];
146 extern char *saved_command_line;
147 extern unsigned int saved_command_line_len;
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 init_rootfs(void);
154
155 void init_IRQ(void);
156 void time_init(void);
157 void poking_init(void);
158 void pgtable_cache_init(void);
159
160 extern initcall_entry_t __initcall_start[];
161 extern initcall_entry_t __initcall0_start[];
162 extern initcall_entry_t __initcall1_start[];
163 extern initcall_entry_t __initcall2_start[];
164 extern initcall_entry_t __initcall3_start[];
165 extern initcall_entry_t __initcall4_start[];
166 extern initcall_entry_t __initcall5_start[];
167 extern initcall_entry_t __initcall6_start[];
168 extern initcall_entry_t __initcall7_start[];
169 extern initcall_entry_t __initcall_end[];
170
171 extern struct file_system_type rootfs_fs_type;
172
173 extern bool rodata_enabled;
174 void mark_rodata_ro(void);
175
176 extern void (*late_time_init)(void);
177
178 extern bool initcall_debug;
179
180 #ifdef MODULE
181 extern struct module __this_module;
182 #define THIS_MODULE (&__this_module)
183 #else
184 #define THIS_MODULE ((struct module *)0)
185 #endif
186
187 #endif
188
189 #ifndef MODULE
190
191 #ifndef __ASSEMBLY__
192
193 /*
194 * initcalls are now grouped by functionality into separate
195 * subsections. Ordering inside the subsections is determined
196 * by link order.
197 * For backwards compatibility, initcall() puts the call in
198 * the device init subsection.
199 *
200 * The `id' arg to __define_initcall() is needed so that multiple initcalls
201 * can point at the same handler without causing duplicate-symbol build errors.
202 *
203 * Initcalls are run by placing pointers in initcall sections that the
204 * kernel iterates at runtime. The linker can do dead code / data elimination
205 * and remove that completely, so the initcall sections have to be marked
206 * as KEEP() in the linker script.
207 */
208
209 /* Format: <modname>__<counter>_<line>_<fn> */
210 #define __initcall_id(fn) \
211 __PASTE(__KBUILD_MODNAME, \
212 __PASTE(__, \
213 __PASTE(__COUNTER__, \
214 __PASTE(_, \
215 __PASTE(__LINE__, \
216 __PASTE(_, fn))))))
217
218 /* Format: __<prefix>__<iid><id> */
219 #define __initcall_name(prefix, __iid, id) \
220 __PASTE(__, \
221 __PASTE(prefix, \
222 __PASTE(__, \
223 __PASTE(__iid, id))))
224
225 #ifdef CONFIG_LTO_CLANG
226 /*
227 * With LTO, the compiler doesn't necessarily obey link order for
228 * initcalls. In order to preserve the correct order, we add each
229 * variable into its own section and generate a linker script (in
230 * scripts/link-vmlinux.sh) to specify the order of the sections.
231 */
232 #define __initcall_section(__sec, __iid) \
233 #__sec ".init.." #__iid
234
235 /*
236 * With LTO, the compiler can rename static functions to avoid
237 * global naming collisions. We use a global stub function for
238 * initcalls to create a stable symbol name whose address can be
239 * taken in inline assembly when PREL32 relocations are used.
240 */
241 #define __initcall_stub(fn, __iid, id) \
242 __initcall_name(initstub, __iid, id)
243
244 #define __define_initcall_stub(__stub, fn) \
245 int __init __stub(void); \
246 int __init __stub(void) \
247 { \
248 return fn(); \
249 } \
250 __ADDRESSABLE(__stub)
251 #else
252 #define __initcall_section(__sec, __iid) \
253 #__sec ".init"
254
255 #define __initcall_stub(fn, __iid, id) fn
256
257 #define __define_initcall_stub(__stub, fn) \
258 __ADDRESSABLE(fn)
259 #endif
260
261 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
262 #define ____define_initcall(fn, __stub, __name, __sec) \
263 __define_initcall_stub(__stub, fn) \
264 asm(".section \"" __sec "\", \"a\" \n" \
265 __stringify(__name) ": \n" \
266 ".long " __stringify(__stub) " - . \n" \
267 ".previous \n"); \
268 static_assert(__same_type(initcall_t, &fn));
269 #else
270 #define ____define_initcall(fn, __unused, __name, __sec) \
271 static initcall_t __name __used \
272 __attribute__((__section__(__sec))) = fn;
273 #endif
274
275 #define __unique_initcall(fn, id, __sec, __iid) \
276 ____define_initcall(fn, \
277 __initcall_stub(fn, __iid, id), \
278 __initcall_name(initcall, __iid, id), \
279 __initcall_section(__sec, __iid))
280
281 #define ___define_initcall(fn, id, __sec) \
282 __unique_initcall(fn, id, __sec, __initcall_id(fn))
283
284 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
285
286 /*
287 * Early initcalls run before initializing SMP.
288 *
289 * Only for built-in code, not modules.
290 */
291 #define early_initcall(fn) __define_initcall(fn, early)
292
293 /*
294 * A "pure" initcall has no dependencies on anything else, and purely
295 * initializes variables that couldn't be statically initialized.
296 *
297 * This only exists for built-in code, not for modules.
298 * Keep main.c:initcall_level_names[] in sync.
299 */
300 #define pure_initcall(fn) __define_initcall(fn, 0)
301
302 #define core_initcall(fn) __define_initcall(fn, 1)
303 #define core_initcall_sync(fn) __define_initcall(fn, 1s)
304 #define postcore_initcall(fn) __define_initcall(fn, 2)
305 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s)
306 #define arch_initcall(fn) __define_initcall(fn, 3)
307 #define arch_initcall_sync(fn) __define_initcall(fn, 3s)
308 #define subsys_initcall(fn) __define_initcall(fn, 4)
309 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s)
310 #define fs_initcall(fn) __define_initcall(fn, 5)
311 #define fs_initcall_sync(fn) __define_initcall(fn, 5s)
312 #define rootfs_initcall(fn) __define_initcall(fn, rootfs)
313 #define device_initcall(fn) __define_initcall(fn, 6)
314 #define device_initcall_sync(fn) __define_initcall(fn, 6s)
315 #define late_initcall(fn) __define_initcall(fn, 7)
316 #define late_initcall_sync(fn) __define_initcall(fn, 7s)
317
318 #define __initcall(fn) device_initcall(fn)
319
320 #define __exitcall(fn) \
321 static exitcall_t __exitcall_##fn __exit_call = fn
322
323 #define console_initcall(fn) ___define_initcall(fn, con, .con_initcall)
324
325 struct obs_kernel_param {
326 const char *str;
327 int (*setup_func)(char *);
328 int early;
329 };
330
331 extern const struct obs_kernel_param __setup_start[], __setup_end[];
332
333 /*
334 * Only for really core code. See moduleparam.h for the normal way.
335 *
336 * Force the alignment so the compiler doesn't space elements of the
337 * obs_kernel_param "array" too far apart in .init.setup.
338 */
339 #define __setup_param(str, unique_id, fn, early) \
340 static const char __setup_str_##unique_id[] __initconst \
341 __aligned(1) = str; \
342 static struct obs_kernel_param __setup_##unique_id \
343 __used __section(".init.setup") \
344 __aligned(__alignof__(struct obs_kernel_param)) \
345 = { __setup_str_##unique_id, fn, early }
346
347 /*
348 * NOTE: __setup functions return values:
349 * @fn returns 1 (or non-zero) if the option argument is "handled"
350 * and returns 0 if the option argument is "not handled".
351 */
352 #define __setup(str, fn) \
353 __setup_param(str, fn, fn, 0)
354
355 /*
356 * NOTE: @fn is as per module_param, not __setup!
357 * I.e., @fn returns 0 for no error or non-zero for error
358 * (possibly @fn returns a -errno value, but it does not matter).
359 * Emits warning if @fn returns non-zero.
360 */
361 #define early_param(str, fn) \
362 __setup_param(str, fn, fn, 1)
363
364 #define early_param_on_off(str_on, str_off, var, config) \
365 \
366 int var = IS_ENABLED(config); \
367 \
368 static int __init parse_##var##_on(char *arg) \
369 { \
370 var = 1; \
371 return 0; \
372 } \
373 early_param(str_on, parse_##var##_on); \
374 \
375 static int __init parse_##var##_off(char *arg) \
376 { \
377 var = 0; \
378 return 0; \
379 } \
380 early_param(str_off, parse_##var##_off)
381
382 /* Relies on boot_command_line being set */
383 void __init parse_early_param(void);
384 void __init parse_early_options(char *cmdline);
385 #endif /* __ASSEMBLY__ */
386
387 #else /* MODULE */
388
389 #define __setup_param(str, unique_id, fn) /* nothing */
390 #define __setup(str, func) /* nothing */
391 #endif
392
393 /* Data marked not to be saved by software suspend */
394 #define __nosavedata __section(".data..nosave")
395
396 #ifdef MODULE
397 #define __exit_p(x) x
398 #else
399 #define __exit_p(x) NULL
400 #endif
401
402 #endif /* _LINUX_INIT_H */
403