1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 #ifndef _LINUX_EXPORT_H 3 #define _LINUX_EXPORT_H 4 5 /* 6 * Export symbols from the kernel to modules. Forked from module.h 7 * to reduce the amount of pointless cruft we feed to gcc when only 8 * exporting a simple symbol or two. 9 * 10 * Try not to add #includes here. It slows compilation and makes kernel 11 * hackers place grumpy comments in header files. 12 */ 13 14 #ifndef __ASSEMBLY__ 15 #ifdef MODULE 16 extern struct module __this_module; 17 #define THIS_MODULE (&__this_module) 18 #else 19 #define THIS_MODULE ((struct module *)0) 20 #endif 21 22 #ifdef CONFIG_MODVERSIONS 23 /* Mark the CRC weak since genksyms apparently decides not to 24 * generate a checksums for some symbols */ 25 #if defined(CONFIG_MODULE_REL_CRCS) 26 #define __CRC_SYMBOL(sym, sec) \ 27 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ 28 " .weak __crc_" #sym " \n" \ 29 " .long __crc_" #sym " - . \n" \ 30 " .previous \n") 31 #else 32 #define __CRC_SYMBOL(sym, sec) \ 33 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \ 34 " .weak __crc_" #sym " \n" \ 35 " .long __crc_" #sym " \n" \ 36 " .previous \n") 37 #endif 38 #else 39 #define __CRC_SYMBOL(sym, sec) 40 #endif 41 42 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 43 #include <linux/compiler.h> 44 /* 45 * Emit the ksymtab entry as a pair of relative references: this reduces 46 * the size by half on 64-bit architectures, and eliminates the need for 47 * absolute relocations that require runtime processing on relocatable 48 * kernels. 49 */ 50 #define __KSYMTAB_ENTRY_NS(sym, sec) \ 51 __ADDRESSABLE(sym) \ 52 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ 53 " .balign 4 \n" \ 54 "__ksymtab_" #sym ": \n" \ 55 " .long " #sym "- . \n" \ 56 " .long __kstrtab_" #sym "- . \n" \ 57 " .long __kstrtabns_" #sym "- . \n" \ 58 " .previous \n") 59 60 #define __KSYMTAB_ENTRY(sym, sec) \ 61 __ADDRESSABLE(sym) \ 62 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ 63 " .balign 4 \n" \ 64 "__ksymtab_" #sym ": \n" \ 65 " .long " #sym "- . \n" \ 66 " .long __kstrtab_" #sym "- . \n" \ 67 " .long 0 \n" \ 68 " .previous \n") 69 70 struct kernel_symbol { 71 int value_offset; 72 int name_offset; 73 int namespace_offset; 74 }; 75 #else 76 #define __KSYMTAB_ENTRY_NS(sym, sec) \ 77 static const struct kernel_symbol __ksymtab_##sym \ 78 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 79 __aligned(sizeof(void *)) \ 80 = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym } 81 82 #define __KSYMTAB_ENTRY(sym, sec) \ 83 static const struct kernel_symbol __ksymtab_##sym \ 84 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 85 __aligned(sizeof(void *)) \ 86 = { (unsigned long)&sym, __kstrtab_##sym, NULL } 87 88 struct kernel_symbol { 89 unsigned long value; 90 const char *name; 91 const char *namespace; 92 }; 93 #endif 94 95 #ifdef __GENKSYMS__ 96 97 #define ___EXPORT_SYMBOL(sym,sec) __GENKSYMS_EXPORT_SYMBOL(sym) 98 #define ___EXPORT_SYMBOL_NS(sym,sec,ns) __GENKSYMS_EXPORT_SYMBOL(sym) 99 100 #else 101 102 #define ___export_symbol_common(sym, sec) \ 103 extern typeof(sym) sym; \ 104 __CRC_SYMBOL(sym, sec); \ 105 static const char __kstrtab_##sym[] \ 106 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 107 = #sym \ 108 109 /* For every exported symbol, place a struct in the __ksymtab section */ 110 #define ___EXPORT_SYMBOL_NS(sym, sec, ns) \ 111 ___export_symbol_common(sym, sec); \ 112 static const char __kstrtabns_##sym[] \ 113 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ 114 = #ns; \ 115 __KSYMTAB_ENTRY_NS(sym, sec) 116 117 #define ___EXPORT_SYMBOL(sym, sec) \ 118 ___export_symbol_common(sym, sec); \ 119 __KSYMTAB_ENTRY(sym, sec) 120 121 #endif 122 123 #if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS) 124 125 /* 126 * Allow symbol exports to be disabled completely so that C code may 127 * be reused in other execution contexts such as the UEFI stub or the 128 * decompressor. 129 */ 130 #define __EXPORT_SYMBOL_NS(sym, sec, ns) 131 #define __EXPORT_SYMBOL(sym, sec) 132 133 #elif defined(CONFIG_TRIM_UNUSED_KSYMS) 134 135 #include <generated/autoksyms.h> 136 137 /* 138 * For fine grained build dependencies, we want to tell the build system 139 * about each possible exported symbol even if they're not actually exported. 140 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters 141 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are 142 * discarded in the final link stage. 143 */ 144 #define __ksym_marker(sym) \ 145 static int __ksym_marker_##sym[0] __section(".discard.ksym") __used 146 147 #define __EXPORT_SYMBOL(sym, sec) \ 148 __ksym_marker(sym); \ 149 __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym)) 150 #define __cond_export_sym(sym, sec, conf) \ 151 ___cond_export_sym(sym, sec, conf) 152 #define ___cond_export_sym(sym, sec, enabled) \ 153 __cond_export_sym_##enabled(sym, sec) 154 #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) 155 #define __cond_export_sym_0(sym, sec) /* nothing */ 156 157 #define __EXPORT_SYMBOL_NS(sym, sec, ns) \ 158 __ksym_marker(sym); \ 159 __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) 160 #define __cond_export_ns_sym(sym, sec, ns, conf) \ 161 ___cond_export_ns_sym(sym, sec, ns, conf) 162 #define ___cond_export_ns_sym(sym, sec, ns, enabled) \ 163 __cond_export_ns_sym_##enabled(sym, sec, ns) 164 #define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns) 165 #define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */ 166 167 #else 168 169 #define __EXPORT_SYMBOL_NS(sym,sec,ns) ___EXPORT_SYMBOL_NS(sym,sec,ns) 170 #define __EXPORT_SYMBOL(sym,sec) ___EXPORT_SYMBOL(sym,sec) 171 172 #endif /* CONFIG_MODULES */ 173 174 #ifdef DEFAULT_SYMBOL_NAMESPACE 175 #undef __EXPORT_SYMBOL 176 #define __EXPORT_SYMBOL(sym, sec) \ 177 __EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE) 178 #endif 179 180 #define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") 181 #define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") 182 #define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") 183 #define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns) 184 #define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns) 185 186 #ifdef CONFIG_UNUSED_SYMBOLS 187 #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") 188 #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl") 189 #else 190 #define EXPORT_UNUSED_SYMBOL(sym) 191 #define EXPORT_UNUSED_SYMBOL_GPL(sym) 192 #endif 193 194 #endif /* !__ASSEMBLY__ */ 195 196 #endif /* _LINUX_EXPORT_H */ 197