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8788994376
Having BUILD_BUG_ON_ZERO produce a value of type size_t leads to awkward casts in cases where the result needs to be signed, or of smaller type than size_t. To avoid this, cast the value to int instead and rely on implicit type conversions when a larger or unsigned type is needed. Link: http://lkml.kernel.org/r/20190811184938.1796-3-rikard.falkeborn@gmail.com Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com> Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Joe Perches <joe@perches.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
80 lines
2.8 KiB
C
80 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_BUILD_BUG_H
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#define _LINUX_BUILD_BUG_H
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#include <linux/compiler.h>
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#ifdef __CHECKER__
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#define BUILD_BUG_ON_ZERO(e) (0)
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#else /* __CHECKER__ */
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/*
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* Force a compilation error if condition is true, but also produce a
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* result (of value 0 and type int), so the expression can be used
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* e.g. in a structure initializer (or where-ever else comma expressions
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* aren't permitted).
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*/
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#define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
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#endif /* __CHECKER__ */
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/* Force a compilation error if a constant expression is not a power of 2 */
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#define __BUILD_BUG_ON_NOT_POWER_OF_2(n) \
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BUILD_BUG_ON(((n) & ((n) - 1)) != 0)
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#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
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BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
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/*
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* BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
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* expression but avoids the generation of any code, even if that expression
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* has side-effects.
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*/
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#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
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/**
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* BUILD_BUG_ON_MSG - break compile if a condition is true & emit supplied
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* error message.
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* @condition: the condition which the compiler should know is false.
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*
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* See BUILD_BUG_ON for description.
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*/
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#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
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/**
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* BUILD_BUG_ON - break compile if a condition is true.
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* @condition: the condition which the compiler should know is false.
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*
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* If you have some code which relies on certain constants being equal, or
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* some other compile-time-evaluated condition, you should use BUILD_BUG_ON to
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* detect if someone changes it.
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*/
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#define BUILD_BUG_ON(condition) \
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BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
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/**
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* BUILD_BUG - break compile if used.
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*
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* If you have some code that you expect the compiler to eliminate at
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* build time, you should use BUILD_BUG to detect if it is
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* unexpectedly used.
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*/
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#define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
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/**
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* static_assert - check integer constant expression at build time
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*
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* static_assert() is a wrapper for the C11 _Static_assert, with a
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* little macro magic to make the message optional (defaulting to the
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* stringification of the tested expression).
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*
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* Contrary to BUILD_BUG_ON(), static_assert() can be used at global
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* scope, but requires the expression to be an integer constant
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* expression (i.e., it is not enough that __builtin_constant_p() is
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* true for expr).
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*
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* Also note that BUILD_BUG_ON() fails the build if the condition is
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* true, while static_assert() fails the build if the expression is
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* false.
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*/
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#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
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#define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
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#endif /* _LINUX_BUILD_BUG_H */
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