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 /* 15 * This comment block is used by fixdep. Please do not remove. 16 * 17 * When CONFIG_MODVERSIONS is changed from n to y, all source files having 18 * EXPORT_SYMBOL variants must be re-compiled because genksyms is run as a 19 * side effect of the *.o build rule. 20 */ 21 22 #ifndef __ASSEMBLY__ 23 #ifdef MODULE 24 extern struct module __this_module; 25 #define THIS_MODULE (&__this_module) 26 #else 27 #define THIS_MODULE ((struct module *)0) 28 #endif 29 30 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS 31 #include <linux/compiler.h> 32 /* 33 * Emit the ksymtab entry as a pair of relative references: this reduces 34 * the size by half on 64-bit architectures, and eliminates the need for 35 * absolute relocations that require runtime processing on relocatable 36 * kernels. 37 */ 38 #define __KSYMTAB_ENTRY(sym, sec) \ 39 __ADDRESSABLE(sym) \ 40 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ 41 " .balign 4 \n" \ 42 "__ksymtab_" #sym ": \n" \ 43 " .long " #sym "- . \n" \ 44 " .long __kstrtab_" #sym "- . \n" \ 45 " .long __kstrtabns_" #sym "- . \n" \ 46 " .previous \n") 47 48 struct kernel_symbol { 49 int value_offset; 50 int name_offset; 51 int namespace_offset; 52 }; 53 #else 54 #define __KSYMTAB_ENTRY(sym, sec) \ 55 static const struct kernel_symbol __ksymtab_##sym \ 56 __attribute__((section("___ksymtab" sec "+" #sym), used)) \ 57 __aligned(sizeof(void *)) \ 58 = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym } 59 60 struct kernel_symbol { 61 unsigned long value; 62 const char *name; 63 const char *namespace; 64 }; 65 #endif 66 67 #ifdef __GENKSYMS__ 68 69 #define ___EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym) 70 71 #else 72 73 /* 74 * For every exported symbol, do the following: 75 * 76 * - Put the name of the symbol and namespace (empty string "" for none) in 77 * __ksymtab_strings. 78 * - Place a struct kernel_symbol entry in the __ksymtab section. 79 * 80 * note on .section use: we specify progbits since usage of the "M" (SHF_MERGE) 81 * section flag requires it. Use '%progbits' instead of '@progbits' since the 82 * former apparently works on all arches according to the binutils source. 83 */ 84 #define ___EXPORT_SYMBOL(sym, sec, ns) \ 85 extern typeof(sym) sym; \ 86 extern const char __kstrtab_##sym[]; \ 87 extern const char __kstrtabns_##sym[]; \ 88 asm(" .section \"__ksymtab_strings\",\"aMS\",%progbits,1 \n" \ 89 "__kstrtab_" #sym ": \n" \ 90 " .asciz \"" #sym "\" \n" \ 91 "__kstrtabns_" #sym ": \n" \ 92 " .asciz \"" ns "\" \n" \ 93 " .previous \n"); \ 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) 129 130 #ifdef __GENKSYMS__ 131 #define __cond_export_sym_0(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym) 132 #else 133 #define __cond_export_sym_0(sym, sec, ns) /* nothing */ 134 #endif 135 136 #else 137 138 #define __EXPORT_SYMBOL(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns) 139 140 #endif /* CONFIG_MODULES */ 141 142 #ifdef DEFAULT_SYMBOL_NAMESPACE 143 #include <linux/stringify.h> 144 #define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE)) 145 #else 146 #define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "") 147 #endif 148 149 #define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym, "") 150 #define EXPORT_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_gpl") 151 #define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL(sym, "", #ns) 152 #define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(sym, "_gpl", #ns) 153 154 #endif /* !__ASSEMBLY__ */ 155 156 #endif /* _LINUX_EXPORT_H */ 157