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[mirror_ubuntu-bionic-kernel.git] / include / linux / export.h
1 #ifndef _LINUX_EXPORT_H
2 #define _LINUX_EXPORT_H
3 /*
4 * Export symbols from the kernel to modules. Forked from module.h
5 * to reduce the amount of pointless cruft we feed to gcc when only
6 * exporting a simple symbol or two.
7 *
8 * Try not to add #includes here. It slows compilation and makes kernel
9 * hackers place grumpy comments in header files.
10 */
11
12 /* Some toolchains use a `_' prefix for all user symbols. */
13 #ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
14 #define __VMLINUX_SYMBOL(x) _##x
15 #define __VMLINUX_SYMBOL_STR(x) "_" #x
16 #else
17 #define __VMLINUX_SYMBOL(x) x
18 #define __VMLINUX_SYMBOL_STR(x) #x
19 #endif
20
21 /* Indirect, so macros are expanded before pasting. */
22 #define VMLINUX_SYMBOL(x) __VMLINUX_SYMBOL(x)
23 #define VMLINUX_SYMBOL_STR(x) __VMLINUX_SYMBOL_STR(x)
24
25 #ifndef __ASSEMBLY__
26 struct kernel_symbol
27 {
28 unsigned long value;
29 const char *name;
30 };
31
32 #ifdef MODULE
33 extern struct module __this_module;
34 #define THIS_MODULE (&__this_module)
35 #else
36 #define THIS_MODULE ((struct module *)0)
37 #endif
38
39 #ifdef CONFIG_MODULES
40
41 #ifndef __GENKSYMS__
42 #ifdef CONFIG_MODVERSIONS
43 /* Mark the CRC weak since genksyms apparently decides not to
44 * generate a checksums for some symbols */
45 #define __CRC_SYMBOL(sym, sec) \
46 extern void *__crc_##sym __attribute__((weak)); \
47 static const unsigned long __kcrctab_##sym \
48 __used \
49 __attribute__((section("___kcrctab" sec "+" #sym), unused)) \
50 = (unsigned long) &__crc_##sym;
51 #else
52 #define __CRC_SYMBOL(sym, sec)
53 #endif
54
55 /* For every exported symbol, place a struct in the __ksymtab section */
56 #define __EXPORT_SYMBOL(sym, sec) \
57 extern typeof(sym) sym; \
58 __CRC_SYMBOL(sym, sec) \
59 static const char __kstrtab_##sym[] \
60 __attribute__((section("__ksymtab_strings"), aligned(1))) \
61 = VMLINUX_SYMBOL_STR(sym); \
62 static const struct kernel_symbol __ksymtab_##sym \
63 __used \
64 __attribute__((section("___ksymtab" sec "+" #sym), unused)) \
65 = { (unsigned long)&sym, __kstrtab_##sym }
66
67 #define EXPORT_SYMBOL(sym) \
68 __EXPORT_SYMBOL(sym, "")
69
70 #define EXPORT_SYMBOL_GPL(sym) \
71 __EXPORT_SYMBOL(sym, "_gpl")
72
73 #define EXPORT_SYMBOL_GPL_FUTURE(sym) \
74 __EXPORT_SYMBOL(sym, "_gpl_future")
75
76 #ifdef CONFIG_UNUSED_SYMBOLS
77 #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
78 #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
79 #else
80 #define EXPORT_UNUSED_SYMBOL(sym)
81 #define EXPORT_UNUSED_SYMBOL_GPL(sym)
82 #endif
83
84 #endif /* __GENKSYMS__ */
85
86 #else /* !CONFIG_MODULES... */
87
88 #define EXPORT_SYMBOL(sym)
89 #define EXPORT_SYMBOL_GPL(sym)
90 #define EXPORT_SYMBOL_GPL_FUTURE(sym)
91 #define EXPORT_UNUSED_SYMBOL(sym)
92 #define EXPORT_UNUSED_SYMBOL_GPL(sym)
93
94 #endif /* CONFIG_MODULES */
95 #endif /* !__ASSEMBLY__ */
96
97 #endif /* _LINUX_EXPORT_H */