linux-kernel - [PATCH] x86/boot: Make gdt 8-byte aligned

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Message-Id: <20190627045525.105266-1-xiaoyao.li@linux.intel.com>
Date:   Thu, 27 Jun 2019 12:55:25 +0800
From:   Xiaoyao Li <xiaoyao.li@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Xiaoyao Li <xiaoyao.li@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86/boot: Make gdt 8-byte aligned

When loading segment descriptor, it uses lock implicitly. Align gdt here
to avoid potential split lock from crossing cache lines case.

Signed-off-by: Xiaoyao Li <xiaoyao.li@...ux.intel.com>
---
 arch/x86/boot/compressed/head_64.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index fafb75c6c592..6233ae35d0d9 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -659,6 +659,7 @@ no_longmode:
 gdt64:
 	.word	gdt_end - gdt
 	.quad   0
+	.balign	8
 gdt:
 	.word	gdt_end - gdt
 	.long	gdt
-- 
2.19.1