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 #ifndef __ASSEMBLY__ 14 #ifdef MODULE 15 extern struct module __this_module; 16 #define THIS_MODULE (&__this_module) 17 #else 18 #define THIS_MODULE ((struct module *)0) 19 #endif 20 21 #ifdef CONFIG_MODULES 22 23 #if defined(__KERNEL__) && !defined(__GENKSYMS__) 24 #ifdef CONFIG_MODVERSIONS 25 /* Mark the CRC weak since genksyms apparently decides not to 26 * generate a checksums for some symbols */ 27 #if defined(CONFIG_MODULE_REL_CRCS) 28 #define __CRC_SYMBOL(sym, sec) \ 29 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ 30 " .weak __crc_" #sym " \n" \ 31 " .long __crc_" #sym " - . \n" \ 32 " .previous \n"); 33 #else 34 #define __CRC_SYMBOL(sym, sec) \ 35 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ 36 " .weak __crc_" #sym " \n" \ 37 " .long __crc_" #sym " \n" \ 38 " .previous \n"); 39 #endif 40 #else 41 #define __CRC_SYMBOL(sym, sec) 42 #endif 43 44 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 45 #include <linux/compiler.h> 46 /* 47 * Emit the ksymtab entry as a pair of relative references: this reduces 48 * the size by half on 64-bit architectures, and eliminates the need for 49 * absolute relocations that require runtime processing on relocatable 50 * kernels. 51 */ 52 #define __KSYMTAB_ENTRY(sym, sec) \ 53 __ADDRESSABLE(sym) \ 54 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ 55 " .balign 8 \n" \ 56 "__ksymtab_" #sym ": \n" \ 57 " .long " #sym "- . \n" \ 58 " .long __kstrtab_" #sym "- . \n" \ 59 " .previous \n") 60 61 struct kernel_symbol { 62 int value_offset; 63 int name_offset; 64 }; 65 #else 66 #define __KSYMTAB_ENTRY(sym, sec) \ 67 static const struct kernel_symbol __ksymtab_##sym \ 68 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 69 = { (unsigned long)&sym, __kstrtab_##sym } 70 71 struct kernel_symbol { 72 unsigned long value; 73 const char *name; 74 }; 75 #endif 76 77 /* For every exported symbol, place a struct in the __ksymtab section */ 78 #define ___EXPORT_SYMBOL(sym, sec) \ 79 extern typeof(sym) sym; \ 80 __CRC_SYMBOL(sym, sec) \ 81 static const char __kstrtab_##sym[] \ 82 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 83 = #sym; \ 84 __KSYMTAB_ENTRY(sym, sec) 85 86 #if defined(__DISABLE_EXPORTS) 87 88 /* 89 * Allow symbol exports to be disabled completely so that C code may 90 * be reused in other execution contexts such as the UEFI stub or the 91 * decompressor. 92 */ 93 #define __EXPORT_SYMBOL(sym, sec) 94 95 #elif defined(CONFIG_TRIM_UNUSED_KSYMS) 96 97 #include <generated/autoksyms.h> 98 99 /* 100 * For fine grained build dependencies, we want to tell the build system 101 * about each possible exported symbol even if they're not actually exported. 102 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters 103 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are 104 * discarded in the final link stage. 105 */ 106 #define __ksym_marker(sym) \ 107 static int __ksym_marker_##sym[0] __section(".discard.ksym") __used 108 109 #define __EXPORT_SYMBOL(sym, sec) \ 110 __ksym_marker(sym); \ 111 __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym)) 112 #define __cond_export_sym(sym, sec, conf) \ 113 ___cond_export_sym(sym, sec, conf) 114 #define ___cond_export_sym(sym, sec, enabled) \ 115 __cond_export_sym_##enabled(sym, sec) 116 #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) 117 #define __cond_export_sym_0(sym, sec) /* nothing */ 118 119 #else 120 #define __EXPORT_SYMBOL ___EXPORT_SYMBOL 121 #endif 122 123 #define EXPORT_SYMBOL(sym) \ 124 __EXPORT_SYMBOL(sym, "") 125 126 #define EXPORT_SYMBOL_GPL(sym) \ 127 __EXPORT_SYMBOL(sym, "_gpl") 128 129 #define EXPORT_SYMBOL_GPL_FUTURE(sym) \ 130 __EXPORT_SYMBOL(sym, "_gpl_future") 131 132 #ifdef CONFIG_UNUSED_SYMBOLS 133 #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") 134 #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl") 135 #else 136 #define EXPORT_UNUSED_SYMBOL(sym) 137 #define EXPORT_UNUSED_SYMBOL_GPL(sym) 138 #endif 139 140 #endif /* __GENKSYMS__ */ 141 142 #else /* !CONFIG_MODULES... */ 143 144 #define EXPORT_SYMBOL(sym) 145 #define EXPORT_SYMBOL_GPL(sym) 146 #define EXPORT_SYMBOL_GPL_FUTURE(sym) 147 #define EXPORT_UNUSED_SYMBOL(sym) 148 #define EXPORT_UNUSED_SYMBOL_GPL(sym) 149 150 #endif /* CONFIG_MODULES */ 151 #endif /* !__ASSEMBLY__ */ 152 153 #endif /* _LINUX_EXPORT_H */ 154