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 #define NS_SEPARATOR "." 22 23 #ifdef CONFIG_MODVERSIONS 24 /* Mark the CRC weak since genksyms apparently decides not to 25 * generate a checksums for some symbols */ 26 #if defined(CONFIG_MODULE_REL_CRCS) 27 #define __CRC_SYMBOL(sym, sec) \ 28 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ 29 " .weak __crc_" #sym " \n" \ 30 " .long __crc_" #sym " - . \n" \ 31 " .previous \n") 32 #else 33 #define __CRC_SYMBOL(sym, sec) \ 34 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ 35 " .weak __crc_" #sym " \n" \ 36 " .long __crc_" #sym " \n" \ 37 " .previous \n") 38 #endif 39 #else 40 #define __CRC_SYMBOL(sym, sec) 41 #endif 42 43 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 44 #include <linux/compiler.h> 45 /* 46 * Emit the ksymtab entry as a pair of relative references: this reduces 47 * the size by half on 64-bit architectures, and eliminates the need for 48 * absolute relocations that require runtime processing on relocatable 49 * kernels. 50 */ 51 #define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ 52 __ADDRESSABLE(sym) \ 53 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ 54 " .balign 4 \n" \ 55 "__ksymtab_" #ns NS_SEPARATOR #sym ": \n" \ 56 " .long " #sym "- . \n" \ 57 " .long __kstrtab_" #sym "- . \n" \ 58 " .long __kstrtabns_" #sym "- . \n" \ 59 " .previous \n") 60 61 #define __KSYMTAB_ENTRY(sym, sec) \ 62 __ADDRESSABLE(sym) \ 63 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ 64 " .balign 4 \n" \ 65 "__ksymtab_" #sym ": \n" \ 66 " .long " #sym "- . \n" \ 67 " .long __kstrtab_" #sym "- . \n" \ 68 " .long 0 \n" \ 69 " .previous \n") 70 71 struct kernel_symbol { 72 int value_offset; 73 int name_offset; 74 int namespace_offset; 75 }; 76 #else 77 #define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ 78 static const struct kernel_symbol __ksymtab_##sym##__##ns \ 79 asm("__ksymtab_" #ns NS_SEPARATOR #sym) \ 80 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 81 __aligned(sizeof(void *)) \ 82 = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym } 83 84 #define __KSYMTAB_ENTRY(sym, sec) \ 85 static const struct kernel_symbol __ksymtab_##sym \ 86 asm("__ksymtab_" #sym) \ 87 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 88 __aligned(sizeof(void *)) \ 89 = { (unsigned long)&sym, __kstrtab_##sym, NULL } 90 91 struct kernel_symbol { 92 unsigned long value; 93 const char *name; 94 const char *namespace; 95 }; 96 #endif 97 98 #ifdef __GENKSYMS__ 99 100 #define ___EXPORT_SYMBOL(sym,sec) __GENKSYMS_EXPORT_SYMBOL(sym) 101 #define ___EXPORT_SYMBOL_NS(sym,sec,ns) __GENKSYMS_EXPORT_SYMBOL(sym) 102 103 #else 104 105 #define ___export_symbol_common(sym, sec) \ 106 extern typeof(sym) sym; \ 107 __CRC_SYMBOL(sym, sec); \ 108 static const char __kstrtab_##sym[] \ 109 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 110 = #sym \ 111 112 /* For every exported symbol, place a struct in the __ksymtab section */ 113 #define ___EXPORT_SYMBOL_NS(sym, sec, ns) \ 114 ___export_symbol_common(sym, sec); \ 115 static const char __kstrtabns_##sym[] \ 116 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 117 = #ns; \ 118 __KSYMTAB_ENTRY_NS(sym, sec, ns) 119 120 #define ___EXPORT_SYMBOL(sym, sec) \ 121 ___export_symbol_common(sym, sec); \ 122 __KSYMTAB_ENTRY(sym, sec) 123 124 #endif 125 126 #if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS) 127 128 /* 129 * Allow symbol exports to be disabled completely so that C code may 130 * be reused in other execution contexts such as the UEFI stub or the 131 * decompressor. 132 */ 133 #define __EXPORT_SYMBOL_NS(sym, sec, ns) 134 #define __EXPORT_SYMBOL(sym, sec) 135 136 #elif defined(CONFIG_TRIM_UNUSED_KSYMS) 137 138 #include <generated/autoksyms.h> 139 140 /* 141 * For fine grained build dependencies, we want to tell the build system 142 * about each possible exported symbol even if they're not actually exported. 143 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters 144 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are 145 * discarded in the final link stage. 146 */ 147 #define __ksym_marker(sym) \ 148 static int __ksym_marker_##sym[0] __section(".discard.ksym") __used 149 150 #define __EXPORT_SYMBOL(sym, sec) \ 151 __ksym_marker(sym); \ 152 __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym)) 153 #define __cond_export_sym(sym, sec, conf) \ 154 ___cond_export_sym(sym, sec, conf) 155 #define ___cond_export_sym(sym, sec, enabled) \ 156 __cond_export_sym_##enabled(sym, sec) 157 #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) 158 #define __cond_export_sym_0(sym, sec) /* nothing */ 159 160 #define __EXPORT_SYMBOL_NS(sym, sec, ns) \ 161 __ksym_marker(sym); \ 162 __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) 163 #define __cond_export_ns_sym(sym, sec, ns, conf) \ 164 ___cond_export_ns_sym(sym, sec, ns, conf) 165 #define ___cond_export_ns_sym(sym, sec, ns, enabled) \ 166 __cond_export_ns_sym_##enabled(sym, sec, ns) 167 #define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns) 168 #define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */ 169 170 #else 171 172 #define __EXPORT_SYMBOL_NS(sym,sec,ns) ___EXPORT_SYMBOL_NS(sym,sec,ns) 173 #define __EXPORT_SYMBOL(sym,sec) ___EXPORT_SYMBOL(sym,sec) 174 175 #endif /* CONFIG_MODULES */ 176 177 #ifdef DEFAULT_SYMBOL_NAMESPACE 178 #undef __EXPORT_SYMBOL 179 #define __EXPORT_SYMBOL(sym, sec) \ 180 __EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE) 181 #endif 182 183 #define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") 184 #define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") 185 #define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") 186 #define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns) 187 #define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns) 188 189 #ifdef CONFIG_UNUSED_SYMBOLS 190 #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") 191 #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl") 192 #else 193 #define EXPORT_UNUSED_SYMBOL(sym) 194 #define EXPORT_UNUSED_SYMBOL_GPL(sym) 195 #endif 196 197 #endif /* !__ASSEMBLY__ */ 198 199 #endif /* _LINUX_EXPORT_H */ 200