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 #if defined(CONFIG_MODULE_REL_CRCS)
47 #define __CRC_SYMBOL(sym, sec) \
48 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
49 " .weak " VMLINUX_SYMBOL_STR(__crc_##sym) " \n" \
50 " .long " VMLINUX_SYMBOL_STR(__crc_##sym) " - . \n" \
51 " .previous \n");
52 #else
53 #define __CRC_SYMBOL(sym, sec) \
54 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
55 " .weak " VMLINUX_SYMBOL_STR(__crc_##sym) " \n" \
56 " .long " VMLINUX_SYMBOL_STR(__crc_##sym) " \n" \
57 " .previous \n");
58 #endif
59 #else
60 #define __CRC_SYMBOL(sym, sec)
61 #endif
62
63 /* For every exported symbol, place a struct in the __ksymtab section */
64 #define ___EXPORT_SYMBOL(sym, sec) \
65 extern typeof(sym) sym; \
66 __CRC_SYMBOL(sym, sec) \
67 static const char __kstrtab_##sym[] \
68 __attribute__((section("__ksymtab_strings"), aligned(1))) \
69 = VMLINUX_SYMBOL_STR(sym); \
70 static const struct kernel_symbol __ksymtab_##sym \
71 __used \
72 __attribute__((section("___ksymtab" sec "+" #sym), used)) \
73 = { (unsigned long)&sym, __kstrtab_##sym }
74
75 #if defined(__KSYM_DEPS__)
76
77 /*
78 * For fine grained build dependencies, we want to tell the build system
79 * about each possible exported symbol even if they're not actually exported.
80 * We use a string pattern that is unlikely to be valid code that the build
81 * system filters out from the preprocessor output (see ksym_dep_filter
82 * in scripts/Kbuild.include).
83 */
84 #define __EXPORT_SYMBOL(sym, sec) === __KSYM_##sym ===
85
86 #elif defined(CONFIG_TRIM_UNUSED_KSYMS)
87
88 #include <generated/autoksyms.h>
89
90 #define __EXPORT_SYMBOL(sym, sec) \
91 __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
92 #define __cond_export_sym(sym, sec, conf) \
93 ___cond_export_sym(sym, sec, conf)
94 #define ___cond_export_sym(sym, sec, enabled) \
95 __cond_export_sym_##enabled(sym, sec)
96 #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
97 #define __cond_export_sym_0(sym, sec) /* nothing */
98
99 #else
100 #define __EXPORT_SYMBOL ___EXPORT_SYMBOL
101 #endif
102
103 #define EXPORT_SYMBOL(sym) \
104 __EXPORT_SYMBOL(sym, "")
105
106 #define EXPORT_SYMBOL_GPL(sym) \
107 __EXPORT_SYMBOL(sym, "_gpl")
108
109 #define EXPORT_SYMBOL_GPL_FUTURE(sym) \
110 __EXPORT_SYMBOL(sym, "_gpl_future")
111
112 #ifdef CONFIG_UNUSED_SYMBOLS
113 #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
114 #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
115 #else
116 #define EXPORT_UNUSED_SYMBOL(sym)
117 #define EXPORT_UNUSED_SYMBOL_GPL(sym)
118 #endif
119
120 #endif /* __GENKSYMS__ */
121
122 #else /* !CONFIG_MODULES... */
123
124 #define EXPORT_SYMBOL(sym)
125 #define EXPORT_SYMBOL_GPL(sym)
126 #define EXPORT_SYMBOL_GPL_FUTURE(sym)
127 #define EXPORT_UNUSED_SYMBOL(sym)
128 #define EXPORT_UNUSED_SYMBOL_GPL(sym)
129
130 #endif /* CONFIG_MODULES */
131 #endif /* !__ASSEMBLY__ */
132
133 #endif /* _LINUX_EXPORT_H */
134
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