compiler.h, bug.h: prevent double error messages with BUILD_BUG{,_ON}

[deliverable/linux.git] / include / linux / bug.h

#ifndef _LINUX_BUG_H
#define _LINUX_BUG_H

#include <asm/bug.h>
#include <linux/compiler.h>

enum bug_trap_type {
	BUG_TRAP_TYPE_NONE = 0,
	BUG_TRAP_TYPE_WARN = 1,
	BUG_TRAP_TYPE_BUG = 2,
};

struct pt_regs;

#ifdef __CHECKER__
#define BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)
#define BUILD_BUG_ON_ZERO(e) (0)
#define BUILD_BUG_ON_NULL(e) ((void*)0)
#define BUILD_BUG_ON_INVALID(e) (0)
#define BUILD_BUG_ON(condition) (0)
#define BUILD_BUG() (0)
#else /* __CHECKER__ */

/* Force a compilation error if a constant expression is not a power of 2 */
#define BUILD_BUG_ON_NOT_POWER_OF_2(n)			\
	BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))

/* Force a compilation error if condition is true, but also produce a
   result (of value 0 and type size_t), so the expression can be used
   e.g. in a structure initializer (or where-ever else comma expressions
   aren't permitted). */
#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))

/*
 * BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
 * expression but avoids the generation of any code, even if that expression
 * has side-effects.
 */
#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))

/**
 * BUILD_BUG_ON - break compile if a condition is true.
 * @condition: the condition which the compiler should know is false.
 *
 * If you have some code which relies on certain constants being equal, or
 * some other compile-time-evaluated condition, you should use BUILD_BUG_ON to
 * detect if someone changes it.
 *
 * The implementation uses gcc's reluctance to create a negative array, but gcc
 * (as of 4.4) only emits that error for obvious cases (e.g. not arguments to
 * inline functions).  Luckily, in 4.3 they added the "error" function
 * attribute just for this type of case.  Thus, we use a negative sized array
 * (should always create an error on gcc versions older than 4.4) and then call
 * an undefined function with the error attribute (should always create an
 * error on gcc 4.3 and later).  If for some reason, neither creates a
 * compile-time error, we'll still have a link-time error, which is harder to
 * track down.
 */
#ifndef __OPTIMIZE__
#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
#else
#define BUILD_BUG_ON(condition)						\
	do {								\
		bool __cond = !!(condition);				\
		extern void __build_bug_on_failed(void)			\
			__compiletime_error("BUILD_BUG_ON failed");	\
		if (__cond)						\
			__build_bug_on_failed();			\
		__compiletime_error_fallback(__cond);			\
	} while (0)
#endif

/**
 * BUILD_BUG - break compile if used.
 *
 * If you have some code that you expect the compiler to eliminate at
 * build time, you should use BUILD_BUG to detect if it is
 * unexpectedly used.
 */
#define BUILD_BUG()						\
	do {							\
		extern void __build_bug_failed(void)		\
			__compiletime_error("BUILD_BUG failed");\
		__build_bug_failed();				\
	} while (0)

#endif	/* __CHECKER__ */

#ifdef CONFIG_GENERIC_BUG
#include <asm-generic/bug.h>

static inline int is_warning_bug(const struct bug_entry *bug)
{
	return bug->flags & BUGFLAG_WARNING;
}

const struct bug_entry *find_bug(unsigned long bugaddr);

enum bug_trap_type report_bug(unsigned long bug_addr, struct pt_regs *regs);

/* These are defined by the architecture */
int is_valid_bugaddr(unsigned long addr);

#else	/* !CONFIG_GENERIC_BUG */

static inline enum bug_trap_type report_bug(unsigned long bug_addr,
					    struct pt_regs *regs)
{
	return BUG_TRAP_TYPE_BUG;
}

#endif	/* CONFIG_GENERIC_BUG */
#endif	/* _LINUX_BUG_H */