From: "tip-bot2 for Cao Jin" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>,
Cao Jin <caoj.fnst@cn.fujitsu.com>, Borislav Petkov <bp@suse.de>,
Dave Hansen <dave.hansen@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Jann Horn <jannh@google.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nadav Amit <namit@vmware.com>,
Thomas Gleixner <tglx@linutronix.de>, "x86-ml" <x86@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org
Subject: [tip: x86/cleanups] x86/cpufeature: Explain the macro duplication
Date: Wed, 28 Aug 2019 06:49:11 -0000 [thread overview]
Message-ID: <156697495154.15133.9156303181767258276.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20190828061100.27032-1-caoj.fnst@cn.fujitsu.com>
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 <caoj.fnst@cn.fujitsu.com>
AuthorDate: Wed, 28 Aug 2019 14:11:00 +08:00
Committer: Borislav Petkov <bp@suse.de>
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 <bp@alien8.de>
Signed-off-by: Cao Jin <caoj.fnst@cn.fujitsu.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nadav Amit <namit@vmware.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190828061100.27032-1-caoj.fnst@cn.fujitsu.com
---
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) || \
prev parent reply other threads:[~2019-08-28 6:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-28 6:11 [PATCH] x86/cpufeature: explicit comments for duplicate macro Cao jin
2019-08-28 6:42 ` Borislav Petkov
2019-08-28 8:16 ` Cao jin
2019-08-28 6:49 ` tip-bot2 for Cao Jin [this message]
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