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 - break compile if a condition is true.
  35  * @condition: the condition which the compiler should know is false.
  36  *
  37  * If you have some code which relies on certain constants being equal, or
  38  * other compile-time-evaluated condition, you should use BUILD_BUG_ON to
  39  * detect if someone changes it.
  40  *
  41  * The implementation uses gcc's reluctance to create a negative array, but
  42  * gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
  43  * to inline functions).  So as a fallback we use the optimizer; if it can't
  44  * prove the condition is false, it will cause a link error on the undefined
  45  * "__build_bug_on_failed".  This error message can be harder to track down
  46  * though, hence the two different methods.
  47  */
  48 #ifndef __OPTIMIZE__
  49 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
  50 #else
  51 extern int __build_bug_on_failed;
  52 #define BUILD_BUG_ON(condition)                                 \
  53         do {                                                    \
  54                 ((void)sizeof(char[1 - 2*!!(condition)]));      \
  55                 if (condition) __build_bug_on_failed = 1;       \
  56         } while(0)
  57 #endif
  58
  59 /**
  60  * BUILD_BUG - break compile if used.
  61  *
  62  * If you have some code that you expect the compiler to eliminate at
  63  * build time, you should use BUILD_BUG to detect if it is
  64  * unexpectedly used.
  65  */
  66 #define BUILD_BUG()                                             \
  67         do {                                                    \
  68                 extern void __build_bug_failed(void)            \
  69                         __linktime_error("BUILD_BUG failed");   \
  70                 __build_bug_failed();                           \
  71         } while (0)
  72
  73 #endif  /* __CHECKER__ */
  74
  75 #ifdef CONFIG_GENERIC_BUG
  76 #include <asm-generic/bug.h>
  77
  78 static inline int is_warning_bug(const struct bug_entry *bug)
  79 {
  80         return bug->flags & BUGFLAG_WARNING;
  81 }
  82
  83 const struct bug_entry *find_bug(unsigned long bugaddr);
  84
  85 enum bug_trap_type report_bug(unsigned long bug_addr, struct pt_regs *regs);
  86
  87 /* These are defined by the architecture */
  88 int is_valid_bugaddr(unsigned long addr);
  89
  90 #else   /* !CONFIG_GENERIC_BUG */
  91
  92 static inline enum bug_trap_type report_bug(unsigned long bug_addr,
  93                                             struct pt_regs *regs)
  94 {
  95         return BUG_TRAP_TYPE_BUG;
  96 }
  97
  98 #endif  /* CONFIG_GENERIC_BUG */
  99 #endif  /* _LINUX_BUG_H */