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