include/linux/bug.h

   1 #ifndef _LINUX_BUG_H
   2 #define _LINUX_BUG_H
   3
   4 #include <asm/bug.h>
   5
   6 enum bug_trap_type {
   7         BUG_TRAP_TYPE_NONE = 0,
   8         BUG_TRAP_TYPE_WARN = 1,
   9         BUG_TRAP_TYPE_BUG = 2,
  10 };
  11
  12 struct pt_regs;
  13
  14 #ifdef __CHECKER__
  15 #define BUILD_BUG_ON_NOT_POWER_OF_2(n)
  16 #define BUILD_BUG_ON_ZERO(e) (0)
  17 #define BUILD_BUG_ON_NULL(e) ((void*)0)
  18 #define BUILD_BUG_ON(condition)
  19 #define BUILD_BUG() (0)
  20 #else /* __CHECKER__ */
  21
  22 /* Force a compilation error if a constant expression is not a power of 2 */
  23 #define BUILD_BUG_ON_NOT_POWER_OF_2(n)                  \
  24         BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
  25
  26 /* Force a compilation error if condition is true, but also produce a
  27    result (of value 0 and type size_t), so the expression can be used
  28    e.g. in a structure initializer (or where-ever else comma expressions
  29    aren't permitted). */
  30 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
  31 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
  32
  33 /*
  34  * BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
  35  * expression but avoids the generation of any code, even if that expression
  36  * has side-effects.
  37  */
  38 #define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
  39
  40 /**
  41  * BUILD_BUG_ON - break compile if a condition is true.
  42  * @condition: the condition which the compiler should know is false.
  43  *
  44  * If you have some code which relies on certain constants being equal, or
  45  * other compile-time-evaluated condition, you should use BUILD_BUG_ON to
  46  * detect if someone changes it.
  47  *
  48  * The implementation uses gcc's reluctance to create a negative array, but
  49  * gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
  50  * to inline functions).  So as a fallback we use the optimizer; if it can't
  51  * prove the condition is false, it will cause a link error on the undefined
  52  * "__build_bug_on_failed".  This error message can be harder to track down
  53  * though, hence the two different methods.
  54  */
  55 #ifndef __OPTIMIZE__
  56 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
  57 #else
  58 extern int __build_bug_on_failed;
  59 #define BUILD_BUG_ON(condition)                                 \
  60         do {                                                    \
  61                 ((void)sizeof(char[1 - 2*!!(condition)]));      \
  62                 if (condition) __build_bug_on_failed = 1;       \
  63         } while(0)
  64 #endif
  65
  66 /**
  67  * BUILD_BUG - break compile if used.
  68  *
  69  * If you have some code that you expect the compiler to eliminate at
  70  * build time, you should use BUILD_BUG to detect if it is
  71  * unexpectedly used.
  72  */
  73 #define BUILD_BUG()                                             \
  74         do {                                                    \
  75                 extern void __build_bug_failed(void)            \
  76                         __linktime_error("BUILD_BUG failed");   \
  77                 __build_bug_failed();                           \
  78         } while (0)
  79
  80 #endif  /* __CHECKER__ */
  81
  82 #ifdef CONFIG_GENERIC_BUG
  83 #include <asm-generic/bug.h>
  84
  85 static inline int is_warning_bug(const struct bug_entry *bug)
  86 {
  87         return bug->flags & BUGFLAG_WARNING;
  88 }
  89
  90 const struct bug_entry *find_bug(unsigned long bugaddr);
  91
  92 enum bug_trap_type report_bug(unsigned long bug_addr, struct pt_regs *regs);
  93
  94 /* These are defined by the architecture */
  95 int is_valid_bugaddr(unsigned long addr);
  96
  97 #else   /* !CONFIG_GENERIC_BUG */
  98
  99 static inline enum bug_trap_type report_bug(unsigned long bug_addr,
 100                                             struct pt_regs *regs)
 101 {
 102         return BUG_TRAP_TYPE_BUG;
 103 }
 104
 105 #endif  /* CONFIG_GENERIC_BUG */
 106 #endif  /* _LINUX_BUG_H */