xref: /openbmc/linux/include/linux/export.h (revision fa7f32422ea1ac276b45b96a540ed5981caaa61f)
1 #ifndef _LINUX_EXPORT_H
2 #define _LINUX_EXPORT_H
3 
4 /*
5  * Export symbols from the kernel to modules.  Forked from module.h
6  * to reduce the amount of pointless cruft we feed to gcc when only
7  * exporting a simple symbol or two.
8  *
9  * Try not to add #includes here.  It slows compilation and makes kernel
10  * hackers place grumpy comments in header files.
11  */
12 
13 /* Some toolchains use a `_' prefix for all user symbols. */
14 #ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
15 #define __VMLINUX_SYMBOL(x) _##x
16 #define __VMLINUX_SYMBOL_STR(x) "_" #x
17 #else
18 #define __VMLINUX_SYMBOL(x) x
19 #define __VMLINUX_SYMBOL_STR(x) #x
20 #endif
21 
22 /* Indirect, so macros are expanded before pasting. */
23 #define VMLINUX_SYMBOL(x) __VMLINUX_SYMBOL(x)
24 #define VMLINUX_SYMBOL_STR(x) __VMLINUX_SYMBOL_STR(x)
25 
26 #ifndef __ASSEMBLY__
27 struct kernel_symbol
28 {
29 	unsigned long value;
30 	const char *name;
31 };
32 
33 #ifdef MODULE
34 extern struct module __this_module;
35 #define THIS_MODULE (&__this_module)
36 #else
37 #define THIS_MODULE ((struct module *)0)
38 #endif
39 
40 #ifdef CONFIG_MODULES
41 
42 #if defined(__KERNEL__) && !defined(__GENKSYMS__)
43 #ifdef CONFIG_MODVERSIONS
44 /* Mark the CRC weak since genksyms apparently decides not to
45  * generate a checksums for some symbols */
46 #define __CRC_SYMBOL(sym, sec)						\
47 	extern __visible void *__crc_##sym __attribute__((weak));	\
48 	static const unsigned long __kcrctab_##sym			\
49 	__used								\
50 	__attribute__((section("___kcrctab" sec "+" #sym), used))	\
51 	= (unsigned long) &__crc_##sym;
52 #else
53 #define __CRC_SYMBOL(sym, sec)
54 #endif
55 
56 /* For every exported symbol, place a struct in the __ksymtab section */
57 #define ___EXPORT_SYMBOL(sym, sec)					\
58 	extern typeof(sym) sym;						\
59 	__CRC_SYMBOL(sym, sec)						\
60 	static const char __kstrtab_##sym[]				\
61 	__attribute__((section("__ksymtab_strings"), aligned(1)))	\
62 	= VMLINUX_SYMBOL_STR(sym);					\
63 	static const struct kernel_symbol __ksymtab_##sym		\
64 	__used								\
65 	__attribute__((section("___ksymtab" sec "+" #sym), used))	\
66 	= { (unsigned long)&sym, __kstrtab_##sym }
67 
68 #if defined(__KSYM_DEPS__)
69 
70 /*
71  * For fine grained build dependencies, we want to tell the build system
72  * about each possible exported symbol even if they're not actually exported.
73  * We use a string pattern that is unlikely to be valid code that the build
74  * system filters out from the preprocessor output (see ksym_dep_filter
75  * in scripts/Kbuild.include).
76  */
77 #define __EXPORT_SYMBOL(sym, sec)	=== __KSYM_##sym ===
78 
79 #elif defined(CONFIG_TRIM_UNUSED_KSYMS)
80 
81 #include <generated/autoksyms.h>
82 
83 #define __EXPORT_SYMBOL(sym, sec)				\
84 	__cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
85 #define __cond_export_sym(sym, sec, conf)			\
86 	___cond_export_sym(sym, sec, conf)
87 #define ___cond_export_sym(sym, sec, enabled)			\
88 	__cond_export_sym_##enabled(sym, sec)
89 #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
90 #define __cond_export_sym_0(sym, sec) /* nothing */
91 
92 #else
93 #define __EXPORT_SYMBOL ___EXPORT_SYMBOL
94 #endif
95 
96 #define EXPORT_SYMBOL(sym)					\
97 	__EXPORT_SYMBOL(sym, "")
98 
99 #define EXPORT_SYMBOL_GPL(sym)					\
100 	__EXPORT_SYMBOL(sym, "_gpl")
101 
102 #define EXPORT_SYMBOL_GPL_FUTURE(sym)				\
103 	__EXPORT_SYMBOL(sym, "_gpl_future")
104 
105 #ifdef CONFIG_UNUSED_SYMBOLS
106 #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
107 #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
108 #else
109 #define EXPORT_UNUSED_SYMBOL(sym)
110 #define EXPORT_UNUSED_SYMBOL_GPL(sym)
111 #endif
112 
113 #endif	/* __GENKSYMS__ */
114 
115 #else /* !CONFIG_MODULES... */
116 
117 #define EXPORT_SYMBOL(sym)
118 #define EXPORT_SYMBOL_GPL(sym)
119 #define EXPORT_SYMBOL_GPL_FUTURE(sym)
120 #define EXPORT_UNUSED_SYMBOL(sym)
121 #define EXPORT_UNUSED_SYMBOL_GPL(sym)
122 
123 #endif /* CONFIG_MODULES */
124 #endif /* !__ASSEMBLY__ */
125 
126 #endif /* _LINUX_EXPORT_H */
127