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x86/boot: Make the GDT 8-byte aligned

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The segment descriptors are loaded with an implicitly LOCK-ed instruction,
which could trigger the split lock #AC exception if the variable is not
properly aligned and crosses a cache line.

Align the GDT properly so the descriptors are all 8 byte aligned.

Signed-off-by: Xiaoyao Li <xiaoyao.li@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lkml.kernel.org/r/20190627045525.105266-1-xiaoyao.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Xiaoyao Li 2019-06-27 12:55:25 +08:00 committed by Ingo Molnar
parent 5a949b3883
commit 2238246ff8
1 changed files with 1 additions and 0 deletions
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arch/x86/boot/compressed/head_64.S
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@ -659,6 +659,7 @@ no_longmode:
gdt64: gdt64:
.word gdt_end - gdt .word gdt_end - gdt
.quad 0 .quad 0
.balign 8
gdt: gdt:
.word gdt_end - gdt .word gdt_end - gdt
.long gdt .long gdt