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/* These macros are used to mark some functions or
11 * initialized data (doesn't apply to uninitialized data)
12 * as `initialization' functions. The kernel can take this
13 * as hint that the function is used only during the initialization
14 * phase and free up used memory resources after
15 *
16 * Usage:
17 * For functions:
18 *
19 * You should add __init immediately before the function name, like:
20 *
21 * static void __init initme(int x, int y)
22 * {
23 * extern int z; z = x * y;
24 * }
25 *
26 * If the function has a prototype somewhere, you can also add
27 * __init between closing brace of the prototype and semicolon:
28 *
29 * extern int initialize_foobar_device(int, int, int) __init;
30 *
31 * For initialized data:
32 * You should insert __initdata or __initconst between the variable name
33 * and equal sign followed by value, e.g.:
34 *
35 * static int init_variable __initdata = 0;
36 * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
37 *
38 * Don't forget to initialize data not at file scope, i.e. within a function,
39 * as gcc otherwise puts the data into the bss section and not into the init
40 * section.
41 */
42
43/* These are for everybody (although not all archs will actually
44 discard it in modules) */
45#define __init __section(".init.text") __cold __latent_entropy \
46 __no_kstack_erase
47#define __initdata __section(".init.data")
48#define __initconst __section(".init.rodata")
49#define __exitdata __section(".exit.data")
50#define __exit_call __used __section(".exitcall.exit")
51
52/*
53 * modpost check for section mismatches during the kernel build.
54 * A section mismatch happens when there are references from a
55 * code or data section to an init section (both code or data).
56 * The init sections are (for most archs) discarded by the kernel
57 * when early init has completed so all such references are potential bugs.
58 * For exit sections the same issue exists.
59 *
60 * The following markers are used for the cases where the reference to
61 * the *init / *exit section (code or data) is valid and will teach
62 * modpost not to issue a warning. Intended semantics is that a code or
63 * data tagged __ref* can reference code or data from init section without
64 * producing a warning (of course, no warning does not mean code is
65 * correct, so optimally document why the __ref is needed and why it's OK).
66 *
67 * The markers follow same syntax rules as __init / __initdata.
68 */
69#define __ref __section(".ref.text") noinline
70#define __refdata __section(".ref.data")
71#define __refconst __section(".ref.rodata")
72
73#ifdef MODULE
74#define __exitused
75#else
76#define __exitused __used
77#endif
78
79#define __exit __section(".exit.text") __exitused __cold notrace
80
81#ifdef CONFIG_MEMORY_HOTPLUG
82#define __meminit
83#define __meminitdata
84#define __meminitconst
85#else
86#define __meminit __init
87#define __meminitdata __initdata
88#define __meminitconst __initconst
89#endif
90
91/* For assembly routines */
92#define __HEAD .section ".head.text","ax"
93#define __INIT .section ".init.text","ax"
94#define __FINIT .previous
95
96#define __INITDATA .section ".init.data","aw",%progbits
97#define __INITRODATA .section ".init.rodata","a",%progbits
98#define __FINITDATA .previous
99
100/* silence warnings when references are OK */
101#define __REF .section ".ref.text", "ax"
102#define __REFDATA .section ".ref.data", "aw"
103#define __REFCONST .section ".ref.rodata", "a"
104
105#ifndef __ASSEMBLY__
106/*
107 * Used for initialization calls..
108 */
109typedef int (*initcall_t)(void);
110typedef void (*exitcall_t)(void);
111
112#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
113typedef int initcall_entry_t;
114
115static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
116{
117 return offset_to_ptr(off: entry);
118}
119#else
120typedef initcall_t initcall_entry_t;
121
122static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
123{
124 return *entry;
125}
126#endif
127
128extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
129
130/* Used for constructor calls. */
131typedef void (*ctor_fn_t)(void);
132
133struct file_system_type;
134
135/* Defined in init/main.c */
136extern int do_one_initcall(initcall_t fn);
137extern char __initdata boot_command_line[];
138extern char *saved_command_line;
139extern unsigned int saved_command_line_len;
140extern unsigned int reset_devices;
141
142/* used by init/main.c */
143void setup_arch(char **);
144void prepare_namespace(void);
145void __init init_rootfs(void);
146
147void init_IRQ(void);
148void time_init(void);
149void poking_init(void);
150void pgtable_cache_init(void);
151
152extern initcall_entry_t __initcall_start[];
153extern initcall_entry_t __initcall0_start[];
154extern initcall_entry_t __initcall1_start[];
155extern initcall_entry_t __initcall2_start[];
156extern initcall_entry_t __initcall3_start[];
157extern initcall_entry_t __initcall4_start[];
158extern initcall_entry_t __initcall5_start[];
159extern initcall_entry_t __initcall6_start[];
160extern initcall_entry_t __initcall7_start[];
161extern initcall_entry_t __initcall_end[];
162
163extern struct file_system_type rootfs_fs_type;
164
165extern bool rodata_enabled;
166void mark_rodata_ro(void);
167
168extern void (*late_time_init)(void);
169
170extern bool initcall_debug;
171
172#ifdef MODULE
173extern struct module __this_module;
174#define THIS_MODULE (&__this_module)
175#else
176#define THIS_MODULE ((struct module *)0)
177#endif
178
179#endif
180
181#ifndef MODULE
182
183#ifndef __ASSEMBLY__
184
185/*
186 * initcalls are now grouped by functionality into separate
187 * subsections. Ordering inside the subsections is determined
188 * by link order.
189 * For backwards compatibility, initcall() puts the call in
190 * the device init subsection.
191 *
192 * The `id' arg to __define_initcall() is needed so that multiple initcalls
193 * can point at the same handler without causing duplicate-symbol build errors.
194 *
195 * Initcalls are run by placing pointers in initcall sections that the
196 * kernel iterates at runtime. The linker can do dead code / data elimination
197 * and remove that completely, so the initcall sections have to be marked
198 * as KEEP() in the linker script.
199 */
200
201/* Format: <modname>__<counter>_<line>_<fn> */
202#define __initcall_id(fn) \
203 __PASTE(__KBUILD_MODNAME, \
204 __PASTE(__, \
205 __PASTE(__COUNTER__, \
206 __PASTE(_, \
207 __PASTE(__LINE__, \
208 __PASTE(_, fn))))))
209
210/* Format: __<prefix>__<iid><id> */
211#define __initcall_name(prefix, __iid, id) \
212 __PASTE(__, \
213 __PASTE(prefix, \
214 __PASTE(__, \
215 __PASTE(__iid, id))))
216
217#ifdef CONFIG_LTO_CLANG
218/*
219 * With LTO, the compiler doesn't necessarily obey link order for
220 * initcalls. In order to preserve the correct order, we add each
221 * variable into its own section and generate a linker script (in
222 * scripts/link-vmlinux.sh) to specify the order of the sections.
223 */
224#define __initcall_section(__sec, __iid) \
225 #__sec ".init.." #__iid
226
227/*
228 * With LTO, the compiler can rename static functions to avoid
229 * global naming collisions. We use a global stub function for
230 * initcalls to create a stable symbol name whose address can be
231 * taken in inline assembly when PREL32 relocations are used.
232 */
233#define __initcall_stub(fn, __iid, id) \
234 __initcall_name(initstub, __iid, id)
235
236#define __define_initcall_stub(__stub, fn) \
237 int __init __stub(void); \
238 int __init __stub(void) \
239 { \
240 return fn(); \
241 } \
242 __ADDRESSABLE(__stub)
243#else
244#define __initcall_section(__sec, __iid) \
245 #__sec ".init"
246
247#define __initcall_stub(fn, __iid, id) fn
248
249#define __define_initcall_stub(__stub, fn) \
250 __ADDRESSABLE(fn)
251#endif
252
253#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
254#define ____define_initcall(fn, __stub, __name, __sec) \
255 __define_initcall_stub(__stub, fn) \
256 asm(".section \"" __sec "\", \"a\" \n" \
257 __stringify(__name) ": \n" \
258 ".long " __stringify(__stub) " - . \n" \
259 ".previous \n"); \
260 static_assert(__same_type(initcall_t, &fn));
261#else
262#define ____define_initcall(fn, __unused, __name, __sec) \
263 static initcall_t __name __used \
264 __attribute__((__section__(__sec))) = fn;
265#endif
266
267#define __unique_initcall(fn, id, __sec, __iid) \
268 ____define_initcall(fn, \
269 __initcall_stub(fn, __iid, id), \
270 __initcall_name(initcall, __iid, id), \
271 __initcall_section(__sec, __iid))
272
273#define ___define_initcall(fn, id, __sec) \
274 __unique_initcall(fn, id, __sec, __initcall_id(fn))
275
276#define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
277
278/*
279 * Early initcalls run before initializing SMP.
280 *
281 * Only for built-in code, not modules.
282 */
283#define early_initcall(fn) __define_initcall(fn, early)
284
285/*
286 * A "pure" initcall has no dependencies on anything else, and purely
287 * initializes variables that couldn't be statically initialized.
288 *
289 * This only exists for built-in code, not for modules.
290 * Keep main.c:initcall_level_names[] in sync.
291 */
292#define pure_initcall(fn) __define_initcall(fn, 0)
293
294#define core_initcall(fn) __define_initcall(fn, 1)
295#define core_initcall_sync(fn) __define_initcall(fn, 1s)
296#define postcore_initcall(fn) __define_initcall(fn, 2)
297#define postcore_initcall_sync(fn) __define_initcall(fn, 2s)
298#define arch_initcall(fn) __define_initcall(fn, 3)
299#define arch_initcall_sync(fn) __define_initcall(fn, 3s)
300#define subsys_initcall(fn) __define_initcall(fn, 4)
301#define subsys_initcall_sync(fn) __define_initcall(fn, 4s)
302#define fs_initcall(fn) __define_initcall(fn, 5)
303#define fs_initcall_sync(fn) __define_initcall(fn, 5s)
304#define rootfs_initcall(fn) __define_initcall(fn, rootfs)
305#define device_initcall(fn) __define_initcall(fn, 6)
306#define device_initcall_sync(fn) __define_initcall(fn, 6s)
307#define late_initcall(fn) __define_initcall(fn, 7)
308#define late_initcall_sync(fn) __define_initcall(fn, 7s)
309
310#define __initcall(fn) device_initcall(fn)
311
312#define __exitcall(fn) \
313 static exitcall_t __exitcall_##fn __exit_call = fn
314
315#define console_initcall(fn) ___define_initcall(fn, con, .con_initcall)
316
317struct obs_kernel_param {
318 const char *str;
319 int (*setup_func)(char *);
320 int early;
321};
322
323extern const struct obs_kernel_param __setup_start[], __setup_end[];
324
325/*
326 * Only for really core code. See moduleparam.h for the normal way.
327 *
328 * Force the alignment so the compiler doesn't space elements of the
329 * obs_kernel_param "array" too far apart in .init.setup.
330 */
331#define __setup_param(str, unique_id, fn, early) \
332 static const char __setup_str_##unique_id[] __initconst \
333 __aligned(1) = str; \
334 static struct obs_kernel_param __setup_##unique_id \
335 __used __section(".init.setup") \
336 __aligned(__alignof__(struct obs_kernel_param)) \
337 = { __setup_str_##unique_id, fn, early }
338
339/*
340 * NOTE: __setup functions return values:
341 * @fn returns 1 (or non-zero) if the option argument is "handled"
342 * and returns 0 if the option argument is "not handled".
343 */
344#define __setup(str, fn) \
345 __setup_param(str, fn, fn, 0)
346
347/*
348 * NOTE: @fn is as per module_param, not __setup!
349 * I.e., @fn returns 0 for no error or non-zero for error
350 * (possibly @fn returns a -errno value, but it does not matter).
351 * Emits warning if @fn returns non-zero.
352 */
353#define early_param(str, fn) \
354 __setup_param(str, fn, fn, 1)
355
356#define early_param_on_off(str_on, str_off, var, config) \
357 \
358 int var = IS_ENABLED(config); \
359 \
360 static int __init parse_##var##_on(char *arg) \
361 { \
362 var = 1; \
363 return 0; \
364 } \
365 early_param(str_on, parse_##var##_on); \
366 \
367 static int __init parse_##var##_off(char *arg) \
368 { \
369 var = 0; \
370 return 0; \
371 } \
372 early_param(str_off, parse_##var##_off)
373
374/* Relies on boot_command_line being set */
375void __init parse_early_param(void);
376void __init parse_early_options(char *cmdline);
377#endif /* __ASSEMBLY__ */
378
379#else /* MODULE */
380
381#define __setup_param(str, unique_id, fn) /* nothing */
382#define __setup(str, func) /* nothing */
383#endif
384
385/* Data marked not to be saved by software suspend */
386#define __nosavedata __section(".data..nosave")
387
388#ifdef MODULE
389#define __exit_p(x) x
390#else
391#define __exit_p(x) NULL
392#endif
393
394#endif /* _LINUX_INIT_H */
395