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 #define __memexit __section(".memexit.text") __exitused __cold notrace
93 #define __memexitdata __section(".memexit.data")
94 #define __memexitconst __section(".memexit.rodata")
95
96 /* For assembly routines */
97 #define __HEAD .section ".head.text","ax"
98 #define __INIT .section ".init.text","ax"
99 #define __FINIT .previous
100
101 #define __INITDATA .section ".init.data","aw",%progbits
102 #define __INITRODATA .section ".init.rodata","a",%progbits
103 #define __FINITDATA .previous
104
105 #define __MEMINIT .section ".meminit.text", "ax"
106 #define __MEMINITDATA .section ".meminit.data", "aw"
107 #define __MEMINITRODATA .section ".meminit.rodata", "a"
108
109 /* silence warnings when references are OK */
110 #define __REF .section ".ref.text", "ax"
111 #define __REFDATA .section ".ref.data", "aw"
112 #define __REFCONST .section ".ref.rodata", "a"
113
114 #ifndef __ASSEMBLY__
115 /*
116 * Used for initialization calls..
117 */
118 typedef int (*initcall_t)(void);
119 typedef void (*exitcall_t)(void);
120
121 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
122 typedef int initcall_entry_t;
123
initcall_from_entry(initcall_entry_t * entry)124 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
125 {
126 return offset_to_ptr(entry);
127 }
128 #else
129 typedef initcall_t initcall_entry_t;
130
initcall_from_entry(initcall_entry_t * entry)131 static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
132 {
133 return *entry;
134 }
135 #endif
136
137 extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
138
139 /* Used for constructor calls. */
140 typedef void (*ctor_fn_t)(void);
141
142 struct file_system_type;
143
144 /* Defined in init/main.c */
145 extern int do_one_initcall(initcall_t fn);
146 extern char __initdata boot_command_line[];
147 extern char *saved_command_line;
148 extern unsigned int saved_command_line_len;
149 extern unsigned int reset_devices;
150
151 /* used by init/main.c */
152 void setup_arch(char **);
153 void prepare_namespace(void);
154 void __init init_rootfs(void);
155 extern struct file_system_type rootfs_fs_type;
156
157 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
158 extern bool rodata_enabled;
159 #endif
160 #ifdef CONFIG_STRICT_KERNEL_RWX
161 void mark_rodata_ro(void);
162 #endif
163
164 extern void (*late_time_init)(void);
165
166 extern bool initcall_debug;
167
168 #endif
169
170 #ifndef MODULE
171
172 #ifndef __ASSEMBLY__
173
174 /*
175 * initcalls are now grouped by functionality into separate
176 * subsections. Ordering inside the subsections is determined
177 * by link order.
178 * For backwards compatibility, initcall() puts the call in
179 * the device init subsection.
180 *
181 * The `id' arg to __define_initcall() is needed so that multiple initcalls
182 * can point at the same handler without causing duplicate-symbol build errors.
183 *
184 * Initcalls are run by placing pointers in initcall sections that the
185 * kernel iterates at runtime. The linker can do dead code / data elimination
186 * and remove that completely, so the initcall sections have to be marked
187 * as KEEP() in the linker script.
188 */
189
190 /* Format: <modname>__<counter>_<line>_<fn> */
191 #define __initcall_id(fn) \
192 __PASTE(__KBUILD_MODNAME, \
193 __PASTE(__, \
194 __PASTE(__COUNTER__, \
195 __PASTE(_, \
196 __PASTE(__LINE__, \
197 __PASTE(_, fn))))))
198
199 /* Format: __<prefix>__<iid><id> */
200 #define __initcall_name(prefix, __iid, id) \
201 __PASTE(__, \
202 __PASTE(prefix, \
203 __PASTE(__, \
204 __PASTE(__iid, id))))
205
206 #ifdef CONFIG_LTO_CLANG
207 /*
208 * With LTO, the compiler doesn't necessarily obey link order for
209 * initcalls. In order to preserve the correct order, we add each
210 * variable into its own section and generate a linker script (in
211 * scripts/link-vmlinux.sh) to specify the order of the sections.
212 */
213 #define __initcall_section(__sec, __iid) \
214 #__sec ".init.." #__iid
215
216 /*
217 * With LTO, the compiler can rename static functions to avoid
218 * global naming collisions. We use a global stub function for
219 * initcalls to create a stable symbol name whose address can be
220 * taken in inline assembly when PREL32 relocations are used.
221 */
222 #define __initcall_stub(fn, __iid, id) \
223 __initcall_name(initstub, __iid, id)
224
225 #define __define_initcall_stub(__stub, fn) \
226 int __init __stub(void); \
227 int __init __stub(void) \
228 { \
229 return fn(); \
230 } \
231 __ADDRESSABLE(__stub)
232 #else
233 #define __initcall_section(__sec, __iid) \
234 #__sec ".init"
235
236 #define __initcall_stub(fn, __iid, id) fn
237
238 #define __define_initcall_stub(__stub, fn) \
239 __ADDRESSABLE(fn)
240 #endif
241
242 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
243 #define ____define_initcall(fn, __stub, __name, __sec) \
244 __define_initcall_stub(__stub, fn) \
245 asm(".section \"" __sec "\", \"a\" \n" \
246 __stringify(__name) ": \n" \
247 ".long " __stringify(__stub) " - . \n" \
248 ".previous \n"); \
249 static_assert(__same_type(initcall_t, &fn));
250 #else
251 #define ____define_initcall(fn, __unused, __name, __sec) \
252 static initcall_t __name __used \
253 __attribute__((__section__(__sec))) = fn;
254 #endif
255
256 #define __unique_initcall(fn, id, __sec, __iid) \
257 ____define_initcall(fn, \
258 __initcall_stub(fn, __iid, id), \
259 __initcall_name(initcall, __iid, id), \
260 __initcall_section(__sec, __iid))
261
262 #define ___define_initcall(fn, id, __sec) \
263 __unique_initcall(fn, id, __sec, __initcall_id(fn))
264
265 #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
266
267 /*
268 * Early initcalls run before initializing SMP.
269 *
270 * Only for built-in code, not modules.
271 */
272 #define early_initcall(fn) __define_initcall(fn, early)
273
274 /*
275 * A "pure" initcall has no dependencies on anything else, and purely
276 * initializes variables that couldn't be statically initialized.
277 *
278 * This only exists for built-in code, not for modules.
279 * Keep main.c:initcall_level_names[] in sync.
280 */
281 #define pure_initcall(fn) __define_initcall(fn, 0)
282
283 #define core_initcall(fn) __define_initcall(fn, 1)
284 #define core_initcall_sync(fn) __define_initcall(fn, 1s)
285 #define postcore_initcall(fn) __define_initcall(fn, 2)
286 #define postcore_initcall_sync(fn) __define_initcall(fn, 2s)
287 #define arch_initcall(fn) __define_initcall(fn, 3)
288 #define arch_initcall_sync(fn) __define_initcall(fn, 3s)
289 #define subsys_initcall(fn) __define_initcall(fn, 4)
290 #define subsys_initcall_sync(fn) __define_initcall(fn, 4s)
291 #define fs_initcall(fn) __define_initcall(fn, 5)
292 #define fs_initcall_sync(fn) __define_initcall(fn, 5s)
293 #define rootfs_initcall(fn) __define_initcall(fn, rootfs)
294 #define device_initcall(fn) __define_initcall(fn, 6)
295 #define device_initcall_sync(fn) __define_initcall(fn, 6s)
296 #define late_initcall(fn) __define_initcall(fn, 7)
297 #define late_initcall_sync(fn) __define_initcall(fn, 7s)
298
299 #define __initcall(fn) device_initcall(fn)
300
301 #define __exitcall(fn) \
302 static exitcall_t __exitcall_##fn __exit_call = fn
303
304 #define console_initcall(fn) ___define_initcall(fn, con, .con_initcall)
305
306 struct obs_kernel_param {
307 const char *str;
308 int (*setup_func)(char *);
309 int early;
310 };
311
312 /*
313 * Only for really core code. See moduleparam.h for the normal way.
314 *
315 * Force the alignment so the compiler doesn't space elements of the
316 * obs_kernel_param "array" too far apart in .init.setup.
317 */
318 #define __setup_param(str, unique_id, fn, early) \
319 static const char __setup_str_##unique_id[] __initconst \
320 __aligned(1) = str; \
321 static struct obs_kernel_param __setup_##unique_id \
322 __used __section(".init.setup") \
323 __aligned(__alignof__(struct obs_kernel_param)) \
324 = { __setup_str_##unique_id, fn, early }
325
326 /*
327 * NOTE: __setup functions return values:
328 * @fn returns 1 (or non-zero) if the option argument is "handled"
329 * and returns 0 if the option argument is "not handled".
330 */
331 #define __setup(str, fn) \
332 __setup_param(str, fn, fn, 0)
333
334 /*
335 * NOTE: @fn is as per module_param, not __setup!
336 * I.e., @fn returns 0 for no error or non-zero for error
337 * (possibly @fn returns a -errno value, but it does not matter).
338 * Emits warning if @fn returns non-zero.
339 */
340 #define early_param(str, fn) \
341 __setup_param(str, fn, fn, 1)
342
343 #define early_param_on_off(str_on, str_off, var, config) \
344 \
345 int var = IS_ENABLED(config); \
346 \
347 static int __init parse_##var##_on(char *arg) \
348 { \
349 var = 1; \
350 return 0; \
351 } \
352 early_param(str_on, parse_##var##_on); \
353 \
354 static int __init parse_##var##_off(char *arg) \
355 { \
356 var = 0; \
357 return 0; \
358 } \
359 early_param(str_off, parse_##var##_off)
360
361 /* Relies on boot_command_line being set */
362 void __init parse_early_param(void);
363 void __init parse_early_options(char *cmdline);
364 #endif /* __ASSEMBLY__ */
365
366 #else /* MODULE */
367
368 #define __setup_param(str, unique_id, fn) /* nothing */
369 #define __setup(str, func) /* nothing */
370 #endif
371
372 /* Data marked not to be saved by software suspend */
373 #define __nosavedata __section(".data..nosave")
374
375 #ifdef MODULE
376 #define __exit_p(x) x
377 #else
378 #define __exit_p(x) NULL
379 #endif
380
381 #endif /* _LINUX_INIT_H */
382