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 4 \n" \ 53 "__ksymtab_" #sym ": \n" \ 54 " .long " #sym "- . \n" \ 55 " .long __kstrtab_" #sym "- . \n" \ 56 " .long __kstrtabns_" #sym "- . \n" \ 57 " .previous \n") 58 59 struct kernel_symbol { 60 int value_offset; 61 int name_offset; 62 int namespace_offset; 63 }; 64 #else 65 #define __KSYMTAB_ENTRY(sym, sec) \ 66 static const struct kernel_symbol __ksymtab_##sym \ 67 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 68 __aligned(sizeof(void *)) \ 69 = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym } 70 71 struct kernel_symbol { 72 unsigned long value; 73 const char *name; 74 const char *namespace; 75 }; 76 #endif 77 78 #ifdef __GENKSYMS__ 79 80 #define ___EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym) 81 82 #else 83 84 /* For every exported symbol, place a struct in the __ksymtab section */ 85 #define ___EXPORT_SYMBOL(sym, sec, ns) \ 86 extern typeof(sym) sym; \ 87 __CRC_SYMBOL(sym, sec); \ 88 static const char __kstrtab_##sym[] \ 89 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 90 = #sym; \ 91 static const char __kstrtabns_##sym[] \ 92 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 93 = ns; \ 94 __KSYMTAB_ENTRY(sym, sec) 95 96 #endif 97 98 #if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS) 99 100 /* 101 * Allow symbol exports to be disabled completely so that C code may 102 * be reused in other execution contexts such as the UEFI stub or the 103 * decompressor. 104 */ 105 #define __EXPORT_SYMBOL(sym, sec, ns) 106 107 #elif defined(CONFIG_TRIM_UNUSED_KSYMS) 108 109 #include <generated/autoksyms.h> 110 111 /* 112 * For fine grained build dependencies, we want to tell the build system 113 * about each possible exported symbol even if they're not actually exported. 114 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters 115 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are 116 * discarded in the final link stage. 117 */ 118 #define __ksym_marker(sym) \ 119 static int __ksym_marker_##sym[0] __section(".discard.ksym") __used 120 121 #define __EXPORT_SYMBOL(sym, sec, ns) \ 122 __ksym_marker(sym); \ 123 __cond_export_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) 124 #define __cond_export_sym(sym, sec, ns, conf) \ 125 ___cond_export_sym(sym, sec, ns, conf) 126 #define ___cond_export_sym(sym, sec, ns, enabled) \ 127 __cond_export_sym_##enabled(sym, sec, ns) 128 #define __cond_export_sym_1(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns) 129 #define __cond_export_sym_0(sym, sec, ns) /* nothing */ 130 131 #else 132 133 #define __EXPORT_SYMBOL(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns) 134 135 #endif /* CONFIG_MODULES */ 136 137 #ifdef DEFAULT_SYMBOL_NAMESPACE 138 #include <linux/stringify.h> 139 #define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE)) 140 #else 141 #define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "") 142 #endif 143 144 #define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym, "") 145 #define EXPORT_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_gpl") 146 #define EXPORT_SYMBOL_GPL_FUTURE(sym) _EXPORT_SYMBOL(sym, "_gpl_future") 147 #define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL(sym, "", #ns) 148 #define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(sym, "_gpl", #ns) 149 150 #ifdef CONFIG_UNUSED_SYMBOLS 151 #define EXPORT_UNUSED_SYMBOL(sym) _EXPORT_SYMBOL(sym, "_unused") 152 #define EXPORT_UNUSED_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_unused_gpl") 153 #else 154 #define EXPORT_UNUSED_SYMBOL(sym) 155 #define EXPORT_UNUSED_SYMBOL_GPL(sym) 156 #endif 157 158 #endif /* !__ASSEMBLY__ */ 159 160 #endif /* _LINUX_EXPORT_H */ 161