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