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 /* Used for MEMORY_HOTPLUG */
88 #define __meminit __section(".meminit.text") __cold notrace \
89 __latent_entropy
90 #define __meminitdata __section(".meminit.data")
91 #define __meminitconst __section(".meminit.rodata")
92
93 /* For assembly routines */
94 #define __HEAD .section ".head.text","ax"
95 #define __INIT .section ".init.text","ax"
96 #define __FINIT .previous
97
98 #define __INITDATA .section ".init.data","aw",%progbits
99 #define __INITRODATA .section ".init.rodata","a",%progbits
100 #define __FINITDATA .previous
101
102 #define __MEMINIT .section ".meminit.text", "ax"
103 #define __MEMINITDATA .section ".meminit.data", "aw"
104 #define __MEMINITRODATA .section ".meminit.rodata", "a"
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 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
172 extern bool rodata_enabled;
173 #endif
174 #ifdef CONFIG_STRICT_KERNEL_RWX
175 void mark_rodata_ro(void);
176 #endif
177
178 extern void (*late_time_init)(void);
179
180 extern bool initcall_debug;
181
182 #endif
183
184 #ifndef MODULE
185
186 #ifndef __ASSEMBLY__
187
188 /*
189 * initcalls are now grouped by functionality into separate
190 * subsections. Ordering inside the subsections is determined
191 * by link order.
192 * For backwards compatibility, initcall() puts the call in
193 * the device init subsection.
194 *
195 * The `id' arg to __define_initcall() is needed so that multiple initcalls
196 * can point at the same handler without causing duplicate-symbol build errors.
197 *
198 * Initcalls are run by placing pointers in initcall sections that the
199 * kernel iterates at runtime. The linker can do dead code / data elimination
200 * and remove that completely, so the initcall sections have to be marked
201 * as KEEP() in the linker script.
202 */
203
204 /* Format: <modname>__<counter>_<line>_<fn> */
205 #define __initcall_id(fn) \
206 __PASTE(__KBUILD_MODNAME, \
207 __PASTE(__, \
208 __PASTE(__COUNTER__, \
209 __PASTE(_, \
210 __PASTE(__LINE__, \
211 __PASTE(_, fn))))))
212
213 /* Format: __<prefix>__<iid><id> */
214 #define __initcall_name(prefix, __iid, id) \
215 __PASTE(__, \
216 __PASTE(prefix, \
217 __PASTE(__, \
218 __PASTE(__iid, id))))
219
220 #ifdef CONFIG_LTO_CLANG
221 /*
222 * With LTO, the compiler doesn't necessarily obey link order for
223 * initcalls. In order to preserve the correct order, we add each
224 * variable into its own section and generate a linker script (in
225 * scripts/link-vmlinux.sh) to specify the order of the sections.
226 */
227 #define __initcall_section(__sec, __iid) \
228 #__sec ".init.." #__iid
229
230 /*
231 * With LTO, the compiler can rename static functions to avoid
232 * global naming collisions. We use a global stub function for
233 * initcalls to create a stable symbol name whose address can be
234 * taken in inline assembly when PREL32 relocations are used.
235 */
236 #define __initcall_stub(fn, __iid, id) \
237 __initcall_name(initstub, __iid, id)
238
239 #define __define_initcall_stub(__stub, fn) \
240 int __init __stub(void); \
241 int __init __stub(void) \
242 { \
243 return fn(); \
244 } \
245 __ADDRESSABLE(__stub)
246 #else
247 #define __initcall_section(__sec, __iid) \
248 #__sec ".init"
249
250 #define __initcall_stub(fn, __iid, id) fn
251
252 #define __define_initcall_stub(__stub, fn) \
253 __ADDRESSABLE(fn)
254 #endif
255
256 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
257 #define ____define_initcall(fn, __stub, __name, __sec) \
258 __define_initcall_stub(__stub, fn) \
259 asm(".section \"" __sec "\", \"a\" \n" \
260 __stringify(__name) ": \n" \
261 ".long " __stringify(__stub) " - . \n" \
262 ".previous \n"); \
263 static_assert(__same_type(initcall_t, &fn));
264 #else
265 #define ____define_initcall(fn, __unused, __name, __sec) \
266 static initcall_t __name __used \
267 __attribute__((__section__(__sec))) = fn;
268 #endif
269
270 #define __unique_initcall(fn, id, __sec, __iid) \
271 ____define_initcall(fn, \
272 __initcall_stub(fn, __iid, id), \
273 __initcall_name(initcall, __iid, id), \
274 __initcall_section(__sec, __iid))
275
276 #define ___define_initcall(fn, id, __sec) \
277 __unique_initcall(fn, id, __sec, __initcall_id(fn))
278
279 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
280
281 /*
282 * Early initcalls run before initializing SMP.
283 *
284 * Only for built-in code, not modules.
285 */
286 #define early_initcall(fn) __define_initcall(fn, early)
287
288 /*
289 * A "pure" initcall has no dependencies on anything else, and purely
290 * initializes variables that couldn't be statically initialized.
291 *
292 * This only exists for built-in code, not for modules.
293 * Keep main.c:initcall_level_names[] in sync.
294 */
295 #define pure_initcall(fn) __define_initcall(fn, 0)
296
297 #define core_initcall(fn) __define_initcall(fn, 1)
298 #define core_initcall_sync(fn) __define_initcall(fn, 1s)
299 #define postcore_initcall(fn) __define_initcall(fn, 2)
300 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s)
301 #define arch_initcall(fn) __define_initcall(fn, 3)
302 #define arch_initcall_sync(fn) __define_initcall(fn, 3s)
303 #define subsys_initcall(fn) __define_initcall(fn, 4)
304 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s)
305 #define fs_initcall(fn) __define_initcall(fn, 5)
306 #define fs_initcall_sync(fn) __define_initcall(fn, 5s)
307 #define rootfs_initcall(fn) __define_initcall(fn, rootfs)
308 #define device_initcall(fn) __define_initcall(fn, 6)
309 #define device_initcall_sync(fn) __define_initcall(fn, 6s)
310 #define late_initcall(fn) __define_initcall(fn, 7)
311 #define late_initcall_sync(fn) __define_initcall(fn, 7s)
312
313 #define __initcall(fn) device_initcall(fn)
314
315 #define __exitcall(fn) \
316 static exitcall_t __exitcall_##fn __exit_call = fn
317
318 #define console_initcall(fn) ___define_initcall(fn, con, .con_initcall)
319
320 struct obs_kernel_param {
321 const char *str;
322 int (*setup_func)(char *);
323 int early;
324 };
325
326 extern const struct obs_kernel_param __setup_start[], __setup_end[];
327
328 /*
329 * Only for really core code. See moduleparam.h for the normal way.
330 *
331 * Force the alignment so the compiler doesn't space elements of the
332 * obs_kernel_param "array" too far apart in .init.setup.
333 */
334 #define __setup_param(str, unique_id, fn, early) \
335 static const char __setup_str_##unique_id[] __initconst \
336 __aligned(1) = str; \
337 static struct obs_kernel_param __setup_##unique_id \
338 __used __section(".init.setup") \
339 __aligned(__alignof__(struct obs_kernel_param)) \
340 = { __setup_str_##unique_id, fn, early }
341
342 /*
343 * NOTE: __setup functions return values:
344 * @fn returns 1 (or non-zero) if the option argument is "handled"
345 * and returns 0 if the option argument is "not handled".
346 */
347 #define __setup(str, fn) \
348 __setup_param(str, fn, fn, 0)
349
350 /*
351 * NOTE: @fn is as per module_param, not __setup!
352 * I.e., @fn returns 0 for no error or non-zero for error
353 * (possibly @fn returns a -errno value, but it does not matter).
354 * Emits warning if @fn returns non-zero.
355 */
356 #define early_param(str, fn) \
357 __setup_param(str, fn, fn, 1)
358
359 #define early_param_on_off(str_on, str_off, var, config) \
360 \
361 int var = IS_ENABLED(config); \
362 \
363 static int __init parse_##var##_on(char *arg) \
364 { \
365 var = 1; \
366 return 0; \
367 } \
368 early_param(str_on, parse_##var##_on); \
369 \
370 static int __init parse_##var##_off(char *arg) \
371 { \
372 var = 0; \
373 return 0; \
374 } \
375 early_param(str_off, parse_##var##_off)
376
377 /* Relies on boot_command_line being set */
378 void __init parse_early_param(void);
379 void __init parse_early_options(char *cmdline);
380 #endif /* __ASSEMBLY__ */
381
382 #else /* MODULE */
383
384 #define __setup_param(str, unique_id, fn) /* nothing */
385 #define __setup(str, func) /* nothing */
386 #endif
387
388 /* Data marked not to be saved by software suspend */
389 #define __nosavedata __section(".data..nosave")
390
391 #ifdef MODULE
392 #define __exit_p(x) x
393 #else
394 #define __exit_p(x) NULL
395 #endif
396
397 #endif /* _LINUX_INIT_H */
398