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 #define __MEMINIT .section ".meminit.text", "ax"
107 #define __MEMINITDATA .section ".meminit.data", "aw"
108 #define __MEMINITRODATA .section ".meminit.rodata", "a"
109
110 /* silence warnings when references are OK */
111 #define __REF .section ".ref.text", "ax"
112 #define __REFDATA .section ".ref.data", "aw"
113 #define __REFCONST .section ".ref.rodata", "a"
114
115 #ifndef __ASSEMBLY__
116 /*
117 * Used for initialization calls..
118 */
119 typedef int (*initcall_t)(void);
120 typedef void (*exitcall_t)(void);
121
122 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
123 typedef int initcall_entry_t;
124
initcall_from_entry(initcall_entry_t * entry)125 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
126 {
127 return offset_to_ptr(entry);
128 }
129 #else
130 typedef initcall_t initcall_entry_t;
131
initcall_from_entry(initcall_entry_t * entry)132 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
133 {
134 return *entry;
135 }
136 #endif
137
138 extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
139
140 /* Used for constructor calls. */
141 typedef void (*ctor_fn_t)(void);
142
143 struct file_system_type;
144
145 /* Defined in init/main.c */
146 extern int do_one_initcall(initcall_t fn);
147 extern char __initdata boot_command_line[];
148 extern char *saved_command_line;
149 extern unsigned int saved_command_line_len;
150 extern unsigned int reset_devices;
151
152 /* used by init/main.c */
153 void setup_arch(char **);
154 void prepare_namespace(void);
155 void __init init_rootfs(void);
156
157 void init_IRQ(void);
158 void time_init(void);
159 void poking_init(void);
160 void pgtable_cache_init(void);
161
162 extern initcall_entry_t __initcall_start[];
163 extern initcall_entry_t __initcall0_start[];
164 extern initcall_entry_t __initcall1_start[];
165 extern initcall_entry_t __initcall2_start[];
166 extern initcall_entry_t __initcall3_start[];
167 extern initcall_entry_t __initcall4_start[];
168 extern initcall_entry_t __initcall5_start[];
169 extern initcall_entry_t __initcall6_start[];
170 extern initcall_entry_t __initcall7_start[];
171 extern initcall_entry_t __initcall_end[];
172
173 extern struct file_system_type rootfs_fs_type;
174
175 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
176 extern bool rodata_enabled;
177 #endif
178 #ifdef CONFIG_STRICT_KERNEL_RWX
179 void mark_rodata_ro(void);
180 #endif
181
182 extern void (*late_time_init)(void);
183
184 extern bool initcall_debug;
185
186 #endif
187
188 #ifndef MODULE
189
190 #ifndef __ASSEMBLY__
191
192 /*
193 * initcalls are now grouped by functionality into separate
194 * subsections. Ordering inside the subsections is determined
195 * by link order.
196 * For backwards compatibility, initcall() puts the call in
197 * the device init subsection.
198 *
199 * The `id' arg to __define_initcall() is needed so that multiple initcalls
200 * can point at the same handler without causing duplicate-symbol build errors.
201 *
202 * Initcalls are run by placing pointers in initcall sections that the
203 * kernel iterates at runtime. The linker can do dead code / data elimination
204 * and remove that completely, so the initcall sections have to be marked
205 * as KEEP() in the linker script.
206 */
207
208 /* Format: <modname>__<counter>_<line>_<fn> */
209 #define __initcall_id(fn) \
210 __PASTE(__KBUILD_MODNAME, \
211 __PASTE(__, \
212 __PASTE(__COUNTER__, \
213 __PASTE(_, \
214 __PASTE(__LINE__, \
215 __PASTE(_, fn))))))
216
217 /* Format: __<prefix>__<iid><id> */
218 #define __initcall_name(prefix, __iid, id) \
219 __PASTE(__, \
220 __PASTE(prefix, \
221 __PASTE(__, \
222 __PASTE(__iid, id))))
223
224 #ifdef CONFIG_LTO_CLANG
225 /*
226 * With LTO, the compiler doesn't necessarily obey link order for
227 * initcalls. In order to preserve the correct order, we add each
228 * variable into its own section and generate a linker script (in
229 * scripts/link-vmlinux.sh) to specify the order of the sections.
230 */
231 #define __initcall_section(__sec, __iid) \
232 #__sec ".init.." #__iid
233
234 /*
235 * With LTO, the compiler can rename static functions to avoid
236 * global naming collisions. We use a global stub function for
237 * initcalls to create a stable symbol name whose address can be
238 * taken in inline assembly when PREL32 relocations are used.
239 */
240 #define __initcall_stub(fn, __iid, id) \
241 __initcall_name(initstub, __iid, id)
242
243 #define __define_initcall_stub(__stub, fn) \
244 int __init __stub(void); \
245 int __init __stub(void) \
246 { \
247 return fn(); \
248 } \
249 __ADDRESSABLE(__stub)
250 #else
251 #define __initcall_section(__sec, __iid) \
252 #__sec ".init"
253
254 #define __initcall_stub(fn, __iid, id) fn
255
256 #define __define_initcall_stub(__stub, fn) \
257 __ADDRESSABLE(fn)
258 #endif
259
260 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
261 #define ____define_initcall(fn, __stub, __name, __sec) \
262 __define_initcall_stub(__stub, fn) \
263 asm(".section \"" __sec "\", \"a\" \n" \
264 __stringify(__name) ": \n" \
265 ".long " __stringify(__stub) " - . \n" \
266 ".previous \n"); \
267 static_assert(__same_type(initcall_t, &fn));
268 #else
269 #define ____define_initcall(fn, __unused, __name, __sec) \
270 static initcall_t __name __used \
271 __attribute__((__section__(__sec))) = fn;
272 #endif
273
274 #define __unique_initcall(fn, id, __sec, __iid) \
275 ____define_initcall(fn, \
276 __initcall_stub(fn, __iid, id), \
277 __initcall_name(initcall, __iid, id), \
278 __initcall_section(__sec, __iid))
279
280 #define ___define_initcall(fn, id, __sec) \
281 __unique_initcall(fn, id, __sec, __initcall_id(fn))
282
283 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
284
285 /*
286 * Early initcalls run before initializing SMP.
287 *
288 * Only for built-in code, not modules.
289 */
290 #define early_initcall(fn) __define_initcall(fn, early)
291
292 /*
293 * A "pure" initcall has no dependencies on anything else, and purely
294 * initializes variables that couldn't be statically initialized.
295 *
296 * This only exists for built-in code, not for modules.
297 * Keep main.c:initcall_level_names[] in sync.
298 */
299 #define pure_initcall(fn) __define_initcall(fn, 0)
300
301 #define core_initcall(fn) __define_initcall(fn, 1)
302 #define core_initcall_sync(fn) __define_initcall(fn, 1s)
303 #define postcore_initcall(fn) __define_initcall(fn, 2)
304 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s)
305 #define arch_initcall(fn) __define_initcall(fn, 3)
306 #define arch_initcall_sync(fn) __define_initcall(fn, 3s)
307 #define subsys_initcall(fn) __define_initcall(fn, 4)
308 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s)
309 #define fs_initcall(fn) __define_initcall(fn, 5)
310 #define fs_initcall_sync(fn) __define_initcall(fn, 5s)
311 #define rootfs_initcall(fn) __define_initcall(fn, rootfs)
312 #define device_initcall(fn) __define_initcall(fn, 6)
313 #define device_initcall_sync(fn) __define_initcall(fn, 6s)
314 #define late_initcall(fn) __define_initcall(fn, 7)
315 #define late_initcall_sync(fn) __define_initcall(fn, 7s)
316
317 #define __initcall(fn) device_initcall(fn)
318
319 #define __exitcall(fn) \
320 static exitcall_t __exitcall_##fn __exit_call = fn
321
322 #define console_initcall(fn) ___define_initcall(fn, con, .con_initcall)
323
324 struct obs_kernel_param {
325 const char *str;
326 int (*setup_func)(char *);
327 int early;
328 };
329
330 extern const struct obs_kernel_param __setup_start[], __setup_end[];
331
332 /*
333 * Only for really core code. See moduleparam.h for the normal way.
334 *
335 * Force the alignment so the compiler doesn't space elements of the
336 * obs_kernel_param "array" too far apart in .init.setup.
337 */
338 #define __setup_param(str, unique_id, fn, early) \
339 static const char __setup_str_##unique_id[] __initconst \
340 __aligned(1) = str; \
341 static struct obs_kernel_param __setup_##unique_id \
342 __used __section(".init.setup") \
343 __aligned(__alignof__(struct obs_kernel_param)) \
344 = { __setup_str_##unique_id, fn, early }
345
346 /*
347 * NOTE: __setup functions return values:
348 * @fn returns 1 (or non-zero) if the option argument is "handled"
349 * and returns 0 if the option argument is "not handled".
350 */
351 #define __setup(str, fn) \
352 __setup_param(str, fn, fn, 0)
353
354 /*
355 * NOTE: @fn is as per module_param, not __setup!
356 * I.e., @fn returns 0 for no error or non-zero for error
357 * (possibly @fn returns a -errno value, but it does not matter).
358 * Emits warning if @fn returns non-zero.
359 */
360 #define early_param(str, fn) \
361 __setup_param(str, fn, fn, 1)
362
363 #define early_param_on_off(str_on, str_off, var, config) \
364 \
365 int var = IS_ENABLED(config); \
366 \
367 static int __init parse_##var##_on(char *arg) \
368 { \
369 var = 1; \
370 return 0; \
371 } \
372 early_param(str_on, parse_##var##_on); \
373 \
374 static int __init parse_##var##_off(char *arg) \
375 { \
376 var = 0; \
377 return 0; \
378 } \
379 early_param(str_off, parse_##var##_off)
380
381 /* Relies on boot_command_line being set */
382 void __init parse_early_param(void);
383 void __init parse_early_options(char *cmdline);
384 #endif /* __ASSEMBLY__ */
385
386 #else /* MODULE */
387
388 #define __setup_param(str, unique_id, fn) /* nothing */
389 #define __setup(str, func) /* nothing */
390 #endif
391
392 /* Data marked not to be saved by software suspend */
393 #define __nosavedata __section(".data..nosave")
394
395 #ifdef MODULE
396 #define __exit_p(x) x
397 #else
398 #define __exit_p(x) NULL
399 #endif
400
401 #endif /* _LINUX_INIT_H */
402