LXR linux/include/linux/export.h

   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/* Some toolchains use a `_' prefix for all user symbols. */
  14#ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
  15#define __VMLINUX_SYMBOL(x) _##x
  16#define __VMLINUX_SYMBOL_STR(x) "_" #x
  17#else
  18#define __VMLINUX_SYMBOL(x) x
  19#define __VMLINUX_SYMBOL_STR(x) #x
  20#endif
  21
  22/* Indirect, so macros are expanded before pasting. */
  23#define VMLINUX_SYMBOL(x) __VMLINUX_SYMBOL(x)
  24#define VMLINUX_SYMBOL_STR(x) __VMLINUX_SYMBOL_STR(x)
  25
  26#ifndef __ASSEMBLY__
  27struct kernel_symbol
  28{
  29        unsigned long value;
  30        const char *name;
  31};
  32
  33#ifdef MODULE
  34extern struct module __this_module;
  35#define THIS_MODULE (&__this_module)
  36#else
  37#define THIS_MODULE ((struct module *)0)
  38#endif
  39
  40#ifdef CONFIG_MODULES
  41
  42#if defined(__KERNEL__) && !defined(__GENKSYMS__)
  43#ifdef CONFIG_MODVERSIONS
  44/* Mark the CRC weak since genksyms apparently decides not to
  45 * generate a checksums for some symbols */
  46#define __CRC_SYMBOL(sym, sec)                                          \
  47        extern __visible void *__crc_##sym __attribute__((weak));       \
  48        static const unsigned long __kcrctab_##sym                      \
  49        __used                                                          \
  50        __attribute__((section("___kcrctab" sec "+" #sym), used))       \
  51        = (unsigned long) &__crc_##sym;
  52#else
  53#define __CRC_SYMBOL(sym, sec)
  54#endif
  55
  56/* For every exported symbol, place a struct in the __ksymtab section */
  57#define ___EXPORT_SYMBOL(sym, sec)                                      \
  58        extern typeof(sym) sym;                                         \
  59        __CRC_SYMBOL(sym, sec)                                          \
  60        static const char __kstrtab_##sym[]                             \
  61        __attribute__((section("__ksymtab_strings"), aligned(1)))       \
  62        = VMLINUX_SYMBOL_STR(sym);                                      \
  63        static const struct kernel_symbol __ksymtab_##sym               \
  64        __used                                                          \
  65        __attribute__((section("___ksymtab" sec "+" #sym), used))       \
  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 <generated/autoksyms.h>
  82
  83#define __EXPORT_SYMBOL(sym, sec)                               \
  84        __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
  85#define __cond_export_sym(sym, sec, conf)                       \
  86        ___cond_export_sym(sym, sec, conf)
  87#define ___cond_export_sym(sym, sec, enabled)                   \
  88        __cond_export_sym_##enabled(sym, sec)
  89#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
  90#define __cond_export_sym_0(sym, sec) /* nothing */
  91
  92#else
  93#define __EXPORT_SYMBOL ___EXPORT_SYMBOL
  94#endif
  95
  96#define EXPORT_SYMBOL(sym)                                      \
  97        __EXPORT_SYMBOL(sym, "")
  98
  99#define EXPORT_SYMBOL_GPL(sym)                                  \
 100        __EXPORT_SYMBOL(sym, "_gpl")
 101
 102#define EXPORT_SYMBOL_GPL_FUTURE(sym)                           \
 103        __EXPORT_SYMBOL(sym, "_gpl_future")
 104
 105#ifdef CONFIG_UNUSED_SYMBOLS
 106#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
 107#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
 108#else
 109#define EXPORT_UNUSED_SYMBOL(sym)
 110#define EXPORT_UNUSED_SYMBOL_GPL(sym)
 111#endif
 112
 113#endif  /* __GENKSYMS__ */
 114
 115#else /* !CONFIG_MODULES... */
 116
 117#define EXPORT_SYMBOL(sym)
 118#define EXPORT_SYMBOL_GPL(sym)
 119#define EXPORT_SYMBOL_GPL_FUTURE(sym)
 120#define EXPORT_UNUSED_SYMBOL(sym)
 121#define EXPORT_UNUSED_SYMBOL_GPL(sym)
 122
 123#endif /* CONFIG_MODULES */
 124#endif /* !__ASSEMBLY__ */
 125
 126#endif /* _LINUX_EXPORT_H */
 127