1 /* SPDX-License-Identifier: GPL-2.0-only */
2 #ifndef _LINUX_EXPORT_H
3 #define _LINUX_EXPORT_H
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.
10 * Try not to add #includes here. It slows compilation and makes kernel
11 * hackers place grumpy comments in header files.
16 extern struct module __this_module;
17 #define THIS_MODULE (&__this_module)
19 #define THIS_MODULE ((struct module *)0)
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" \
32 #define __CRC_SYMBOL(sym, sec) \
33 asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
34 " .weak __crc_" #sym " \n" \
35 " .long __crc_" #sym " \n" \
39 #define __CRC_SYMBOL(sym, sec)
42 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
43 #include <linux/compiler.h>
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
50 #define __KSYMTAB_ENTRY(sym, sec) \
52 asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
54 "__ksymtab_" #sym ": \n" \
55 " .long " #sym "- . \n" \
56 " .long __kstrtab_" #sym "- . \n" \
57 " .long __kstrtabns_" #sym "- . \n" \
60 struct kernel_symbol {
66 #define __KSYMTAB_ENTRY(sym, sec) \
67 static const struct kernel_symbol __ksymtab_##sym \
68 __attribute__((section("___ksymtab" sec "+" #sym), used)) \
69 __aligned(sizeof(void *)) \
70 = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym }
72 struct kernel_symbol {
75 const char *namespace;
81 #define ___EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
85 /* For every exported symbol, place a struct in the __ksymtab section */
86 #define ___EXPORT_SYMBOL(sym, sec, ns) \
87 extern typeof(sym) sym; \
88 __CRC_SYMBOL(sym, sec); \
89 static const char __kstrtab_##sym[] \
90 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \
92 static const char __kstrtabns_##sym[] \
93 __attribute__((section("__ksymtab_strings"), used, aligned(1))) \
95 __KSYMTAB_ENTRY(sym, sec)
99 #if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS)
102 * Allow symbol exports to be disabled completely so that C code may
103 * be reused in other execution contexts such as the UEFI stub or the
106 #define __EXPORT_SYMBOL(sym, sec, ns)
108 #elif defined(CONFIG_TRIM_UNUSED_KSYMS)
110 #include <generated/autoksyms.h>
113 * For fine grained build dependencies, we want to tell the build system
114 * about each possible exported symbol even if they're not actually exported.
115 * We use a symbol pattern __ksym_marker_<symbol> that the build system filters
116 * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are
117 * discarded in the final link stage.
119 #define __ksym_marker(sym) \
120 static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
122 #define __EXPORT_SYMBOL(sym, sec, ns) \
123 __ksym_marker(sym); \
124 __cond_export_sym(sym, sec, ns, __is_defined(__KSYM_##sym))
125 #define __cond_export_sym(sym, sec, ns, conf) \
126 ___cond_export_sym(sym, sec, ns, conf)
127 #define ___cond_export_sym(sym, sec, ns, enabled) \
128 __cond_export_sym_##enabled(sym, sec, ns)
129 #define __cond_export_sym_1(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns)
130 #define __cond_export_sym_0(sym, sec, ns) /* nothing */
134 #define __EXPORT_SYMBOL(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns)
136 #endif /* CONFIG_MODULES */
138 #ifdef DEFAULT_SYMBOL_NAMESPACE
139 #include <linux/stringify.h>
140 #define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE))
142 #define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "")
145 #define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym, "")
146 #define EXPORT_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_gpl")
147 #define EXPORT_SYMBOL_GPL_FUTURE(sym) _EXPORT_SYMBOL(sym, "_gpl_future")
148 #define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL(sym, "", #ns)
149 #define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(sym, "_gpl", #ns)
151 #ifdef CONFIG_UNUSED_SYMBOLS
152 #define EXPORT_UNUSED_SYMBOL(sym) _EXPORT_SYMBOL(sym, "_unused")
153 #define EXPORT_UNUSED_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_unused_gpl")
155 #define EXPORT_UNUSED_SYMBOL(sym)
156 #define EXPORT_UNUSED_SYMBOL_GPL(sym)
159 #endif /* !__ASSEMBLY__ */
161 #endif /* _LINUX_EXPORT_H */