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