projects/linux·blob v5.8-rc4 · refs

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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
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 */
116typedef int (*initcall_t)(void);
117typedef void (*exitcall_t)(void);
118
119#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
120typedef int initcall_entry_t;
121
122static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
123{
124 return offset_to_ptr(entry);
125}
126#else
127typedef initcall_t initcall_entry_t;
128
129static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
130{
131 return *entry;
132}
133#endif
134
135extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
136
137/* Used for contructor calls. */
138typedef void (*ctor_fn_t)(void);
139
140struct file_system_type;
141
142/* Defined in init/main.c */
143extern int do_one_initcall(initcall_t fn);
144extern char __initdata boot_command_line[];
145extern char *saved_command_line;
146extern unsigned int reset_devices;
147
148/* used by init/main.c */
149void setup_arch(char **);
150void prepare_namespace(void);
151void __init init_rootfs(void);
152extern struct file_system_type rootfs_fs_type;
153
154#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
155extern bool rodata_enabled;
156#endif
157#ifdef CONFIG_STRICT_KERNEL_RWX
158void mark_rodata_ro(void);
159#endif
160
161extern void (*late_time_init)(void);
162
163extern 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
241struct 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 */
290void __init parse_early_param(void);
291void __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 */