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  #ifdef CONFIG_MEMORY_HOTPLUG
88  #define __meminit
89  #define __meminitdata
90  #define __meminitconst
91  #else
92  #define __meminit	__init
93  #define __meminitdata	__initdata
94  #define __meminitconst	__initconst
95  #endif
96  
97  /* For assembly routines */
98  #define __HEAD		.section	".head.text","ax"
99  #define __INIT		.section	".init.text","ax"
100  #define __FINIT		.previous
101  
102  #define __INITDATA	.section	".init.data","aw",%progbits
103  #define __INITRODATA	.section	".init.rodata","a",%progbits
104  #define __FINITDATA	.previous
105  
106  /* silence warnings when references are OK */
107  #define __REF            .section       ".ref.text", "ax"
108  #define __REFDATA        .section       ".ref.data", "aw"
109  #define __REFCONST       .section       ".ref.rodata", "a"
110  
111  #ifndef __ASSEMBLY__
112  /*
113   * Used for initialization calls..
114   */
115  typedef int (*initcall_t)(void);
116  typedef void (*exitcall_t)(void);
117  
118  #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
119  typedef int initcall_entry_t;
120  
initcall_from_entry(initcall_entry_t * entry)121  static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
122  {
123  	return offset_to_ptr(entry);
124  }
125  #else
126  typedef initcall_t initcall_entry_t;
127  
initcall_from_entry(initcall_entry_t * entry)128  static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
129  {
130  	return *entry;
131  }
132  #endif
133  
134  extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
135  
136  /* Used for constructor calls. */
137  typedef void (*ctor_fn_t)(void);
138  
139  struct file_system_type;
140  
141  /* Defined in init/main.c */
142  extern int do_one_initcall(initcall_t fn);
143  extern char __initdata boot_command_line[];
144  extern char *saved_command_line;
145  extern unsigned int saved_command_line_len;
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  
153  void init_IRQ(void);
154  void time_init(void);
155  void poking_init(void);
156  void pgtable_cache_init(void);
157  
158  extern initcall_entry_t __initcall_start[];
159  extern initcall_entry_t __initcall0_start[];
160  extern initcall_entry_t __initcall1_start[];
161  extern initcall_entry_t __initcall2_start[];
162  extern initcall_entry_t __initcall3_start[];
163  extern initcall_entry_t __initcall4_start[];
164  extern initcall_entry_t __initcall5_start[];
165  extern initcall_entry_t __initcall6_start[];
166  extern initcall_entry_t __initcall7_start[];
167  extern initcall_entry_t __initcall_end[];
168  
169  extern struct file_system_type rootfs_fs_type;
170  
171  extern bool rodata_enabled;
172  void mark_rodata_ro(void);
173  
174  extern void (*late_time_init)(void);
175  
176  extern bool initcall_debug;
177  
178  #ifdef MODULE
179  extern struct module __this_module;
180  #define THIS_MODULE (&__this_module)
181  #else
182  #define THIS_MODULE ((struct module *)0)
183  #endif
184  
185  #endif
186  
187  #ifndef MODULE
188  
189  #ifndef __ASSEMBLY__
190  
191  /*
192   * initcalls are now grouped by functionality into separate
193   * subsections. Ordering inside the subsections is determined
194   * by link order.
195   * For backwards compatibility, initcall() puts the call in
196   * the device init subsection.
197   *
198   * The `id' arg to __define_initcall() is needed so that multiple initcalls
199   * can point at the same handler without causing duplicate-symbol build errors.
200   *
201   * Initcalls are run by placing pointers in initcall sections that the
202   * kernel iterates at runtime. The linker can do dead code / data elimination
203   * and remove that completely, so the initcall sections have to be marked
204   * as KEEP() in the linker script.
205   */
206  
207  /* Format: <modname>__<counter>_<line>_<fn> */
208  #define __initcall_id(fn)					\
209  	__PASTE(__KBUILD_MODNAME,				\
210  	__PASTE(__,						\
211  	__PASTE(__COUNTER__,					\
212  	__PASTE(_,						\
213  	__PASTE(__LINE__,					\
214  	__PASTE(_, fn))))))
215  
216  /* Format: __<prefix>__<iid><id> */
217  #define __initcall_name(prefix, __iid, id)			\
218  	__PASTE(__,						\
219  	__PASTE(prefix,						\
220  	__PASTE(__,						\
221  	__PASTE(__iid, id))))
222  
223  #ifdef CONFIG_LTO_CLANG
224  /*
225   * With LTO, the compiler doesn't necessarily obey link order for
226   * initcalls. In order to preserve the correct order, we add each
227   * variable into its own section and generate a linker script (in
228   * scripts/link-vmlinux.sh) to specify the order of the sections.
229   */
230  #define __initcall_section(__sec, __iid)			\
231  	#__sec ".init.." #__iid
232  
233  /*
234   * With LTO, the compiler can rename static functions to avoid
235   * global naming collisions. We use a global stub function for
236   * initcalls to create a stable symbol name whose address can be
237   * taken in inline assembly when PREL32 relocations are used.
238   */
239  #define __initcall_stub(fn, __iid, id)				\
240  	__initcall_name(initstub, __iid, id)
241  
242  #define __define_initcall_stub(__stub, fn)			\
243  	int __init __stub(void);				\
244  	int __init __stub(void)					\
245  	{ 							\
246  		return fn();					\
247  	}							\
248  	__ADDRESSABLE(__stub)
249  #else
250  #define __initcall_section(__sec, __iid)			\
251  	#__sec ".init"
252  
253  #define __initcall_stub(fn, __iid, id)	fn
254  
255  #define __define_initcall_stub(__stub, fn)			\
256  	__ADDRESSABLE(fn)
257  #endif
258  
259  #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
260  #define ____define_initcall(fn, __stub, __name, __sec)		\
261  	__define_initcall_stub(__stub, fn)			\
262  	asm(".section	\"" __sec "\", \"a\"		\n"	\
263  	    __stringify(__name) ":			\n"	\
264  	    ".long	" __stringify(__stub) " - .	\n"	\
265  	    ".previous					\n");	\
266  	static_assert(__same_type(initcall_t, &fn));
267  #else
268  #define ____define_initcall(fn, __unused, __name, __sec)	\
269  	static initcall_t __name __used 			\
270  		__attribute__((__section__(__sec))) = fn;
271  #endif
272  
273  #define __unique_initcall(fn, id, __sec, __iid)			\
274  	____define_initcall(fn,					\
275  		__initcall_stub(fn, __iid, id),			\
276  		__initcall_name(initcall, __iid, id),		\
277  		__initcall_section(__sec, __iid))
278  
279  #define ___define_initcall(fn, id, __sec)			\
280  	__unique_initcall(fn, id, __sec, __initcall_id(fn))
281  
282  #define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
283  
284  /*
285   * Early initcalls run before initializing SMP.
286   *
287   * Only for built-in code, not modules.
288   */
289  #define early_initcall(fn)		__define_initcall(fn, early)
290  
291  /*
292   * A "pure" initcall has no dependencies on anything else, and purely
293   * initializes variables that couldn't be statically initialized.
294   *
295   * This only exists for built-in code, not for modules.
296   * Keep main.c:initcall_level_names[] in sync.
297   */
298  #define pure_initcall(fn)		__define_initcall(fn, 0)
299  
300  #define core_initcall(fn)		__define_initcall(fn, 1)
301  #define core_initcall_sync(fn)		__define_initcall(fn, 1s)
302  #define postcore_initcall(fn)		__define_initcall(fn, 2)
303  #define postcore_initcall_sync(fn)	__define_initcall(fn, 2s)
304  #define arch_initcall(fn)		__define_initcall(fn, 3)
305  #define arch_initcall_sync(fn)		__define_initcall(fn, 3s)
306  #define subsys_initcall(fn)		__define_initcall(fn, 4)
307  #define subsys_initcall_sync(fn)	__define_initcall(fn, 4s)
308  #define fs_initcall(fn)			__define_initcall(fn, 5)
309  #define fs_initcall_sync(fn)		__define_initcall(fn, 5s)
310  #define rootfs_initcall(fn)		__define_initcall(fn, rootfs)
311  #define device_initcall(fn)		__define_initcall(fn, 6)
312  #define device_initcall_sync(fn)	__define_initcall(fn, 6s)
313  #define late_initcall(fn)		__define_initcall(fn, 7)
314  #define late_initcall_sync(fn)		__define_initcall(fn, 7s)
315  
316  #define __initcall(fn) device_initcall(fn)
317  
318  #define __exitcall(fn)						\
319  	static exitcall_t __exitcall_##fn __exit_call = fn
320  
321  #define console_initcall(fn)	___define_initcall(fn, con, .con_initcall)
322  
323  struct obs_kernel_param {
324  	const char *str;
325  	int (*setup_func)(char *);
326  	int early;
327  };
328  
329  extern const struct obs_kernel_param __setup_start[], __setup_end[];
330  
331  /*
332   * Only for really core code.  See moduleparam.h for the normal way.
333   *
334   * Force the alignment so the compiler doesn't space elements of the
335   * obs_kernel_param "array" too far apart in .init.setup.
336   */
337  #define __setup_param(str, unique_id, fn, early)			\
338  	static const char __setup_str_##unique_id[] __initconst		\
339  		__aligned(1) = str; 					\
340  	static struct obs_kernel_param __setup_##unique_id		\
341  		__used __section(".init.setup")				\
342  		__aligned(__alignof__(struct obs_kernel_param))		\
343  		= { __setup_str_##unique_id, fn, early }
344  
345  /*
346   * NOTE: __setup functions return values:
347   * @fn returns 1 (or non-zero) if the option argument is "handled"
348   * and returns 0 if the option argument is "not handled".
349   */
350  #define __setup(str, fn)						\
351  	__setup_param(str, fn, fn, 0)
352  
353  /*
354   * NOTE: @fn is as per module_param, not __setup!
355   * I.e., @fn returns 0 for no error or non-zero for error
356   * (possibly @fn returns a -errno value, but it does not matter).
357   * Emits warning if @fn returns non-zero.
358   */
359  #define early_param(str, fn)						\
360  	__setup_param(str, fn, fn, 1)
361  
362  #define early_param_on_off(str_on, str_off, var, config)		\
363  									\
364  	int var = IS_ENABLED(config);					\
365  									\
366  	static int __init parse_##var##_on(char *arg)			\
367  	{								\
368  		var = 1;						\
369  		return 0;						\
370  	}								\
371  	early_param(str_on, parse_##var##_on);				\
372  									\
373  	static int __init parse_##var##_off(char *arg)			\
374  	{								\
375  		var = 0;						\
376  		return 0;						\
377  	}								\
378  	early_param(str_off, parse_##var##_off)
379  
380  /* Relies on boot_command_line being set */
381  void __init parse_early_param(void);
382  void __init parse_early_options(char *cmdline);
383  #endif /* __ASSEMBLY__ */
384  
385  #else /* MODULE */
386  
387  #define __setup_param(str, unique_id, fn)	/* nothing */
388  #define __setup(str, func) 			/* nothing */
389  #endif
390  
391  /* Data marked not to be saved by software suspend */
392  #define __nosavedata __section(".data..nosave")
393  
394  #ifdef MODULE
395  #define __exit_p(x) x
396  #else
397  #define __exit_p(x) NULL
398  #endif
399  
400  #endif /* _LINUX_INIT_H */
401