The following commit has been merged into the x86/cleanups branch of tip: Commit-ID: cbb1133b563a63901cf778220eb17e3ff1425aed Gitweb: https://git.kernel.org/tip/cbb1133b563a63901cf778220eb17e3ff1425aed Author: Cao Jin <[email protected]> AuthorDate: Wed, 28 Aug 2019 14:11:00 +08:00 Committer: Borislav Petkov <[email protected]> CommitterDate: Wed, 28 Aug 2019 08:38:39 +02:00
x86/cpufeature: Explain the macro duplication Explain the intent behind the duplication of the BUILD_BUG_ON_ZERO(NCAPINTS != n) check in *_MASK_CHECK and its immediate use in the *MASK_BIT_SET macros too. [ bp: Massage. ] Suggested-by: Borislav Petkov <[email protected]> Signed-off-by: Cao Jin <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Fenghua Yu <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Jann Horn <[email protected]> Cc: Masahiro Yamada <[email protected]> Cc: Michael Ellerman <[email protected]> Cc: Nadav Amit <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: x86-ml <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- arch/x86/include/asm/cpufeature.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 58acda5..59bf91c 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -61,6 +61,13 @@ extern const char * const x86_bug_flags[NBUGINTS*32]; #define CHECK_BIT_IN_MASK_WORD(maskname, word, bit) \ (((bit)>>5)==(word) && (1UL<<((bit)&31) & maskname##word )) +/* + * {REQUIRED,DISABLED}_MASK_CHECK below may seem duplicated with the + * following BUILD_BUG_ON_ZERO() check but when NCAPINTS gets changed, all + * header macros which use NCAPINTS need to be changed. The duplicated macro + * use causes the compiler to issue errors for all headers so that all usage + * sites can be corrected. + */ #define REQUIRED_MASK_BIT_SET(feature_bit) \ ( CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 0, feature_bit) || \ CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 1, feature_bit) || \
