LXR linux/include/linux/export.h

   1#ifndef _LINUX_EXPORT_H
   2#define _LINUX_EXPORT_H
   3/*
   4 * Export symbols from the kernel to modules.  Forked from module.h
   5 * to reduce the amount of pointless cruft we feed to gcc when only
   6 * exporting a simple symbol or two.
   7 *
   8 * Try not to add #includes here.  It slows compilation and makes kernel
   9 * hackers place grumpy comments in header files.
  10 */
  11
  12/* Some toolchains use a `_' prefix for all user symbols. */
  13#ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
  14#define __VMLINUX_SYMBOL(x) _##x
  15#define __VMLINUX_SYMBOL_STR(x) "_" #x
  16#else
  17#define __VMLINUX_SYMBOL(x) x
  18#define __VMLINUX_SYMBOL_STR(x) #x
  19#endif
  20
  21/* Indirect, so macros are expanded before pasting. */
  22#define VMLINUX_SYMBOL(x) __VMLINUX_SYMBOL(x)
  23#define VMLINUX_SYMBOL_STR(x) __VMLINUX_SYMBOL_STR(x)
  24
  25#ifndef __ASSEMBLY__
  26struct kernel_symbol
  27{
  28        unsigned long value;
  29        const char *name;
  30};
  31
  32#ifdef MODULE
  33extern struct module __this_module;
  34#define THIS_MODULE (&__this_module)
  35#else
  36#define THIS_MODULE ((struct module *)0)
  37#endif
  38
  39#ifdef CONFIG_MODULES
  40
  41#if defined(__KERNEL__) && !defined(__GENKSYMS__)
  42#ifdef CONFIG_MODVERSIONS
  43/* Mark the CRC weak since genksyms apparently decides not to
  44 * generate a checksums for some symbols */
  45#define __CRC_SYMBOL(sym, sec)                                  \
  46        extern __visible void *__crc_##sym __attribute__((weak));               \
  47        static const unsigned long __kcrctab_##sym              \
  48        __used                                                  \
  49        __attribute__((section("___kcrctab" sec "+" #sym), unused))     \
  50        = (unsigned long) &__crc_##sym;
  51#else
  52#define __CRC_SYMBOL(sym, sec)
  53#endif
  54
  55/* For every exported symbol, place a struct in the __ksymtab section */
  56#define ___EXPORT_SYMBOL(sym, sec)                              \
  57        extern typeof(sym) sym;                                 \
  58        __CRC_SYMBOL(sym, sec)                                  \
  59        static const char __kstrtab_##sym[]                     \
  60        __attribute__((section("__ksymtab_strings"), aligned(1))) \
  61        = VMLINUX_SYMBOL_STR(sym);                              \
  62        extern const struct kernel_symbol __ksymtab_##sym;      \
  63        __visible const struct kernel_symbol __ksymtab_##sym    \
  64        __used                                                  \
  65        __attribute__((section("___ksymtab" sec "+" #sym), unused))     \
  66        = { (unsigned long)&sym, __kstrtab_##sym }
  67
  68#if defined(__KSYM_DEPS__)
  69
  70/*
  71 * For fine grained build dependencies, we want to tell the build system
  72 * about each possible exported symbol even if they're not actually exported.
  73 * We use a string pattern that is unlikely to be valid code that the build
  74 * system filters out from the preprocessor output (see ksym_dep_filter
  75 * in scripts/Kbuild.include).
  76 */
  77#define __EXPORT_SYMBOL(sym, sec)       === __KSYM_##sym ===
  78
  79#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
  80
  81#include <linux/kconfig.h>
  82#include <generated/autoksyms.h>
  83
  84#define __EXPORT_SYMBOL(sym, sec)                               \
  85        __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
  86#define __cond_export_sym(sym, sec, conf)                       \
  87        ___cond_export_sym(sym, sec, conf)
  88#define ___cond_export_sym(sym, sec, enabled)                   \
  89        __cond_export_sym_##enabled(sym, sec)
  90#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
  91#define __cond_export_sym_0(sym, sec) /* nothing */
  92
  93#else
  94#define __EXPORT_SYMBOL ___EXPORT_SYMBOL
  95#endif
  96
  97#define EXPORT_SYMBOL(sym)                                      \
  98        __EXPORT_SYMBOL(sym, "")
  99
 100#define EXPORT_SYMBOL_GPL(sym)                                  \
 101        __EXPORT_SYMBOL(sym, "_gpl")
 102
 103#define EXPORT_SYMBOL_GPL_FUTURE(sym)                           \
 104        __EXPORT_SYMBOL(sym, "_gpl_future")
 105
 106#ifdef CONFIG_UNUSED_SYMBOLS
 107#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
 108#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
 109#else
 110#define EXPORT_UNUSED_SYMBOL(sym)
 111#define EXPORT_UNUSED_SYMBOL_GPL(sym)
 112#endif
 113
 114#endif  /* __GENKSYMS__ */
 115
 116#else /* !CONFIG_MODULES... */
 117
 118#define EXPORT_SYMBOL(sym)
 119#define EXPORT_SYMBOL_GPL(sym)
 120#define EXPORT_SYMBOL_GPL_FUTURE(sym)
 121#define EXPORT_UNUSED_SYMBOL(sym)
 122#define EXPORT_UNUSED_SYMBOL_GPL(sym)
 123
 124#endif /* CONFIG_MODULES */
 125#endif /* !__ASSEMBLY__ */
 126
 127#endif /* _LINUX_EXPORT_H */
 128