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
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
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
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 #define ___define_initcall(fn, id, __sec) \
196 static initcall_t __initcall_##fn##id __used \
197 __attribute__((__section__(#__sec ".init"))) = fn;
198 #endif
199
200 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
201
202 /*
203 * Early initcalls run before initializing SMP.
204 *
205 * Only for built-in code, not modules.
206 */
207 #define early_initcall(fn) __define_initcall(fn, early)
208
209 /*
210 * A "pure" initcall has no dependencies on anything else, and purely
211 * initializes variables that couldn't be statically initialized.
212 *
213 * This only exists for built-in code, not for modules.
214 * Keep main.c:initcall_level_names[] in sync.
215 */
216 #define pure_initcall(fn) __define_initcall(fn, 0)
217
218 #define core_initcall(fn) __define_initcall(fn, 1)
219 #define core_initcall_sync(fn) __define_initcall(fn, 1s)
220 #define postcore_initcall(fn) __define_initcall(fn, 2)
221 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s)
222 #define arch_initcall(fn) __define_initcall(fn, 3)
223 #define arch_initcall_sync(fn) __define_initcall(fn, 3s)
224 #define subsys_initcall(fn) __define_initcall(fn, 4)
225 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s)
226 #define fs_initcall(fn) __define_initcall(fn, 5)
227 #define fs_initcall_sync(fn) __define_initcall(fn, 5s)
228 #define rootfs_initcall(fn) __define_initcall(fn, rootfs)
229 #define device_initcall(fn) __define_initcall(fn, 6)
230 #define device_initcall_sync(fn) __define_initcall(fn, 6s)
231 #define late_initcall(fn) __define_initcall(fn, 7)
232 #define late_initcall_sync(fn) __define_initcall(fn, 7s)
233
234 #define __initcall(fn) device_initcall(fn)
235
236 #define __exitcall(fn) \
237 static exitcall_t __exitcall_##fn __exit_call = fn
238
239 #define console_initcall(fn) ___define_initcall(fn,, .con_initcall)
240
241 struct obs_kernel_param {
242 const char *str;
243 int (*setup_func)(char *);
244 int early;
245 };
246
247 /*
248 * Only for really core code. See moduleparam.h for the normal way.
249 *
250 * Force the alignment so the compiler doesn't space elements of the
251 * obs_kernel_param "array" too far apart in .init.setup.
252 */
253 #define __setup_param(str, unique_id, fn, early) \
254 static const char __setup_str_##unique_id[] __initconst \
255 __aligned(1) = str; \
256 static struct obs_kernel_param __setup_##unique_id \
257 __used __section(.init.setup) \
258 __attribute__((aligned((sizeof(long))))) \
259 = { __setup_str_##unique_id, fn, early }
260
261 #define __setup(str, fn) \
262 __setup_param(str, fn, fn, 0)
263
264 /*
265 * NOTE: fn is as per module_param, not __setup!
266 * Emits warning if fn returns non-zero.
267 */
268 #define early_param(str, fn) \
269 __setup_param(str, fn, fn, 1)
270
271 #define early_param_on_off(str_on, str_off, var, config) \
272 \
273 int var = IS_ENABLED(config); \
274 \
275 static int __init parse_##var##_on(char *arg) \
276 { \
277 var = 1; \
278 return 0; \
279 } \
280 __setup_param(str_on, parse_##var##_on, parse_##var##_on, 1); \
281 \
282 static int __init parse_##var##_off(char *arg) \
283 { \
284 var = 0; \
285 return 0; \
286 } \
287 __setup_param(str_off, parse_##var##_off, parse_##var##_off, 1)
288
289 /* Relies on boot_command_line being set */
290 void __init parse_early_param(void);
291 void __init parse_early_options(char *cmdline);
292 #endif /* __ASSEMBLY__ */
293
294 #else /* MODULE */
295
296 #define __setup_param(str, unique_id, fn) /* nothing */
297 #define __setup(str, func) /* nothing */
298 #endif
299
300 /* Data marked not to be saved by software suspend */
301 #define __nosavedata __section(.data..nosave)
302
303 #ifdef MODULE
304 #define __exit_p(x) x
305 #else
306 #define __exit_p(x) NULL
307 #endif
308
309 #endif /* _LINUX_INIT_H */
310
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