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