Commit bc6245e5 authored by Ian Abbott's avatar Ian Abbott Committed by Linus Torvalds
Browse files

bug: split BUILD_BUG stuff out into <linux/build_bug.h> 

Including <linux/bug.h> pulls in a lot of bloat from <asm/bug.h> and
<asm-generic/bug.h> that is not needed to call the BUILD_BUG() family of
macros.  Split them out into their own header, <linux/build_bug.h>.

Also correct some checkpatch.pl errors for the BUILD_BUG_ON_ZERO() and
BUILD_BUG_ON_NULL() macros by adding parentheses around the bitfield
widths that begin with a minus sign.

Link: http://lkml.kernel.org/r/20170525120316.24473-6-abbotti@mev.co.uk


Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Acked-by: default avatarMichal Nazarewicz <mina86@mina86.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 47e81e59

include/linux/bug.h

+1 −73
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 


#include <asm/bug.h>

#include <linux/compiler.h>

#include <linux/build_bug.h>



enum bug_trap_type {

	BUG_TRAP_TYPE_NONE = 0,
@@ -13,82 +14,9 @@ enum bug_trap_type { 
struct pt_regs;



#ifdef __CHECKER__

#define __BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)

#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_MSG(cond, msg) (0)

#define BUILD_BUG_ON(condition) (0)

#define BUILD_BUG() (0)

#define MAYBE_BUILD_BUG_ON(cond) (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) & ((n) - 1)) != 0)

#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_MSG - break compile if a condition is true & emit supplied

 *		      error message.

 * @condition: the condition which the compiler should know is false.

 *

 * See BUILD_BUG_ON for description.

 */

#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)



/**

 * 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) \

	BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)

#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() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")



#define MAYBE_BUILD_BUG_ON(cond)			\

	do {						\

		if (__builtin_constant_p((cond)))       \

include/linux/build_bug.h

0 → 100644
+84 −0
Original line number Diff line number Diff line 
#ifndef _LINUX_BUILD_BUG_H

#define _LINUX_BUILD_BUG_H



#include <linux/compiler.h>



#ifdef __CHECKER__

#define __BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)

#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_MSG(cond, msg) (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) & ((n) - 1)) != 0)

#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_MSG - break compile if a condition is true & emit supplied

 *		      error message.

 * @condition: the condition which the compiler should know is false.

 *

 * See BUILD_BUG_ON for description.

 */

#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)



/**

 * 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) \

	BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)

#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() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")



#endif	/* __CHECKER__ */



#endif	/* _LINUX_BUILD_BUG_H */

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