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_NS(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 #define __KSYMTAB_ENTRY(sym, sec) \ 60 __ADDRESSABLE(sym) \ 61 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ 62 " .balign 4 \n" \ 63 "__ksymtab_" #sym ": \n" \ 64 " .long " #sym "- . \n" \ 65 " .long __kstrtab_" #sym "- . \n" \ 66 " .long 0 \n" \ 67 " .previous \n") 68 69 struct kernel_symbol { 70 int value_offset; 71 int name_offset; 72 int namespace_offset; 73 }; 74 #else 75 #define __KSYMTAB_ENTRY_NS(sym, sec) \ 76 static const struct kernel_symbol __ksymtab_##sym \ 77 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 78 __aligned(sizeof(void *)) \ 79 = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym } 80 81 #define __KSYMTAB_ENTRY(sym, sec) \ 82 static const struct kernel_symbol __ksymtab_##sym \ 83 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 84 __aligned(sizeof(void *)) \ 85 = { (unsigned long)&sym, __kstrtab_##sym, NULL } 86 87 struct kernel_symbol { 88 unsigned long value; 89 const char *name; 90 const char *namespace; 91 }; 92 #endif 93 94 #ifdef __GENKSYMS__ 95 96 #define ___EXPORT_SYMBOL(sym,sec) __GENKSYMS_EXPORT_SYMBOL(sym) 97 #define ___EXPORT_SYMBOL_NS(sym,sec,ns) __GENKSYMS_EXPORT_SYMBOL(sym) 98 99 #else 100 101 #define ___export_symbol_common(sym, sec) \ 102 extern typeof(sym) sym; \ 103 __CRC_SYMBOL(sym, sec); \ 104 static const char __kstrtab_##sym[] \ 105 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 106 = #sym \ 107 108 /* For every exported symbol, place a struct in the __ksymtab section */ 109 #define ___EXPORT_SYMBOL_NS(sym, sec, ns) \ 110 ___export_symbol_common(sym, sec); \ 111 static const char __kstrtabns_##sym[] \ 112 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 113 = #ns; \ 114 __KSYMTAB_ENTRY_NS(sym, sec) 115 116 #define ___EXPORT_SYMBOL(sym, sec) \ 117 ___export_symbol_common(sym, sec); \ 118 __KSYMTAB_ENTRY(sym, sec) 119 120 #endif 121 122 #if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS) 123 124 /* 125 * Allow symbol exports to be disabled completely so that C code may 126 * be reused in other execution contexts such as the UEFI stub or the 127 * decompressor. 128 */ 129 #define __EXPORT_SYMBOL_NS(sym, sec, ns) 130 #define __EXPORT_SYMBOL(sym, sec) 131 132 #elif defined(CONFIG_TRIM_UNUSED_KSYMS) 133 134 #include <generated/autoksyms.h> 135 136 /* 137 * For fine grained build dependencies, we want to tell the build system 138 * about each possible exported symbol even if they're not actually exported. 139 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters 140 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are 141 * discarded in the final link stage. 142 */ 143 #define __ksym_marker(sym) \ 144 static int __ksym_marker_##sym[0] __section(".discard.ksym") __used 145 146 #define __EXPORT_SYMBOL(sym, sec) \ 147 __ksym_marker(sym); \ 148 __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym)) 149 #define __cond_export_sym(sym, sec, conf) \ 150 ___cond_export_sym(sym, sec, conf) 151 #define ___cond_export_sym(sym, sec, enabled) \ 152 __cond_export_sym_##enabled(sym, sec) 153 #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) 154 #define __cond_export_sym_0(sym, sec) /* nothing */ 155 156 #define __EXPORT_SYMBOL_NS(sym, sec, ns) \ 157 __ksym_marker(sym); \ 158 __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) 159 #define __cond_export_ns_sym(sym, sec, ns, conf) \ 160 ___cond_export_ns_sym(sym, sec, ns, conf) 161 #define ___cond_export_ns_sym(sym, sec, ns, enabled) \ 162 __cond_export_ns_sym_##enabled(sym, sec, ns) 163 #define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns) 164 #define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */ 165 166 #else 167 168 #define __EXPORT_SYMBOL_NS(sym,sec,ns) ___EXPORT_SYMBOL_NS(sym,sec,ns) 169 #define __EXPORT_SYMBOL(sym,sec) ___EXPORT_SYMBOL(sym,sec) 170 171 #endif /* CONFIG_MODULES */ 172 173 #ifdef DEFAULT_SYMBOL_NAMESPACE 174 #undef __EXPORT_SYMBOL 175 #define __EXPORT_SYMBOL(sym, sec) \ 176 __EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE) 177 #endif 178 179 #define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") 180 #define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") 181 #define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") 182 #define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns) 183 #define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns) 184 185 #ifdef CONFIG_UNUSED_SYMBOLS 186 #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") 187 #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl") 188 #else 189 #define EXPORT_UNUSED_SYMBOL(sym) 190 #define EXPORT_UNUSED_SYMBOL_GPL(sym) 191 #endif 192 193 #endif /* !__ASSEMBLY__ */ 194 195 #endif /* _LINUX_EXPORT_H */ 196