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 #define NS_SEPARATOR "." 24 25 #if defined(__KERNEL__) && !defined(__GENKSYMS__) 26 #ifdef CONFIG_MODVERSIONS 27 /* Mark the CRC weak since genksyms apparently decides not to 28 * generate a checksums for some symbols */ 29 #if defined(CONFIG_MODULE_REL_CRCS) 30 #define __CRC_SYMBOL(sym, sec) \ 31 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ 32 " .weak __crc_" #sym " \n" \ 33 " .long __crc_" #sym " - . \n" \ 34 " .previous \n") 35 #else 36 #define __CRC_SYMBOL(sym, sec) \ 37 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ 38 " .weak __crc_" #sym " \n" \ 39 " .long __crc_" #sym " \n" \ 40 " .previous \n") 41 #endif 42 #else 43 #define __CRC_SYMBOL(sym, sec) 44 #endif 45 46 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 47 #include <linux/compiler.h> 48 /* 49 * Emit the ksymtab entry as a pair of relative references: this reduces 50 * the size by half on 64-bit architectures, and eliminates the need for 51 * absolute relocations that require runtime processing on relocatable 52 * kernels. 53 */ 54 #define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ 55 __ADDRESSABLE(sym) \ 56 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ 57 " .balign 4 \n" \ 58 "__ksymtab_" #sym NS_SEPARATOR #ns ": \n" \ 59 " .long " #sym "- . \n" \ 60 " .long __kstrtab_" #sym "- . \n" \ 61 " .long __kstrtab_ns_" #sym "- . \n" \ 62 " .previous \n") 63 64 #define __KSYMTAB_ENTRY(sym, sec) \ 65 __ADDRESSABLE(sym) \ 66 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ 67 " .balign 4 \n" \ 68 "__ksymtab_" #sym ": \n" \ 69 " .long " #sym "- . \n" \ 70 " .long __kstrtab_" #sym "- . \n" \ 71 " .long 0 - . \n" \ 72 " .previous \n") 73 74 struct kernel_symbol { 75 int value_offset; 76 int name_offset; 77 int namespace_offset; 78 }; 79 #else 80 #define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ 81 static const struct kernel_symbol __ksymtab_##sym##__##ns \ 82 asm("__ksymtab_" #sym NS_SEPARATOR #ns) \ 83 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 84 __aligned(sizeof(void *)) \ 85 = { (unsigned long)&sym, __kstrtab_##sym, __kstrtab_ns_##sym } 86 87 #define __KSYMTAB_ENTRY(sym, sec) \ 88 static const struct kernel_symbol __ksymtab_##sym \ 89 asm("__ksymtab_" #sym) \ 90 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 91 __aligned(sizeof(void *)) \ 92 = { (unsigned long)&sym, __kstrtab_##sym, NULL } 93 94 struct kernel_symbol { 95 unsigned long value; 96 const char *name; 97 const char *namespace; 98 }; 99 #endif 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 __kstrtab_ns_##sym[] \ 112 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 113 = #ns; \ 114 __KSYMTAB_ENTRY_NS(sym, sec, ns) 115 116 #define ___EXPORT_SYMBOL(sym, sec) \ 117 ___export_symbol_common(sym, sec); \ 118 __KSYMTAB_ENTRY(sym, sec) 119 120 #if defined(__DISABLE_EXPORTS) 121 122 /* 123 * Allow symbol exports to be disabled completely so that C code may 124 * be reused in other execution contexts such as the UEFI stub or the 125 * decompressor. 126 */ 127 #define __EXPORT_SYMBOL_NS(sym, sec, ns) 128 #define __EXPORT_SYMBOL(sym, sec) 129 130 #elif defined(CONFIG_TRIM_UNUSED_KSYMS) 131 132 #include <generated/autoksyms.h> 133 134 /* 135 * For fine grained build dependencies, we want to tell the build system 136 * about each possible exported symbol even if they're not actually exported. 137 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters 138 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are 139 * discarded in the final link stage. 140 */ 141 #define __ksym_marker(sym) \ 142 static int __ksym_marker_##sym[0] __section(".discard.ksym") __used 143 144 #define __EXPORT_SYMBOL(sym, sec) \ 145 __ksym_marker(sym); \ 146 __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym)) 147 #define __cond_export_sym(sym, sec, conf) \ 148 ___cond_export_sym(sym, sec, conf) 149 #define ___cond_export_sym(sym, sec, enabled) \ 150 __cond_export_sym_##enabled(sym, sec) 151 #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) 152 #define __cond_export_sym_0(sym, sec) /* nothing */ 153 154 #define __EXPORT_SYMBOL_NS(sym, sec, ns) \ 155 __ksym_marker(sym); \ 156 __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) 157 #define __cond_export_ns_sym(sym, sec, ns, conf) \ 158 ___cond_export_ns_sym(sym, sec, ns, conf) 159 #define ___cond_export_ns_sym(sym, sec, ns, enabled) \ 160 __cond_export_ns_sym_##enabled(sym, sec, ns) 161 #define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns) 162 #define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */ 163 164 #else 165 #define __EXPORT_SYMBOL_NS ___EXPORT_SYMBOL_NS 166 #define __EXPORT_SYMBOL ___EXPORT_SYMBOL 167 #endif 168 169 #ifdef DEFAULT_SYMBOL_NAMESPACE 170 #undef __EXPORT_SYMBOL 171 #define __EXPORT_SYMBOL(sym, sec) \ 172 __EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE) 173 #endif 174 175 #define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") 176 #define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") 177 #define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") 178 #define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns) 179 #define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns) 180 181 #ifdef CONFIG_UNUSED_SYMBOLS 182 #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") 183 #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl") 184 #else 185 #define EXPORT_UNUSED_SYMBOL(sym) 186 #define EXPORT_UNUSED_SYMBOL_GPL(sym) 187 #endif 188 189 #endif /* __KERNEL__ && !__GENKSYMS__ */ 190 191 #if defined(__GENKSYMS__) 192 /* 193 * When we're running genksyms, ignore the namespace and make the _NS 194 * variants look like the normal ones. There are two reasons for this: 195 * 1) In the normal definition of EXPORT_SYMBOL_NS, the 'ns' macro 196 * argument is itself not expanded because it's always tokenized or 197 * concatenated; but when running genksyms, a blank definition of the 198 * macro does allow the argument to be expanded; if a namespace 199 * happens to collide with a #define, this can cause issues. 200 * 2) There's no need to modify genksyms to deal with the _NS variants 201 */ 202 #define EXPORT_SYMBOL_NS(sym, ns) EXPORT_SYMBOL(sym) 203 #define EXPORT_SYMBOL_NS_GPL(sym, ns) EXPORT_SYMBOL_GPL(sym) 204 #endif 205 206 #else /* !CONFIG_MODULES... */ 207 208 #define EXPORT_SYMBOL(sym) 209 #define EXPORT_SYMBOL_NS(sym, ns) 210 #define EXPORT_SYMBOL_NS_GPL(sym, ns) 211 #define EXPORT_SYMBOL_GPL(sym) 212 #define EXPORT_SYMBOL_GPL_FUTURE(sym) 213 #define EXPORT_UNUSED_SYMBOL(sym) 214 #define EXPORT_UNUSED_SYMBOL_GPL(sym) 215 216 #endif /* CONFIG_MODULES */ 217 #endif /* !__ASSEMBLY__ */ 218 219 #endif /* _LINUX_EXPORT_H */ 220