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Date: Wed, 25 Nov 2009 11:17:36 -0500 From: Brian Gerst <brgerst@...il.com> To: Ingo Molnar <mingo@...e.hu> Cc: x86@...nel.org, linux-kernel@...r.kernel.org, Tim Blechmann <tim@...ngt.org> Subject: [PATCH] x86, 64-bit: Set data segments to null after switching to 64-bit mode This prevents kernel threads from inheriting non-null segment selectors, and causing optimizations in __switch_to() to be ineffective. Signed-off-by: Brian Gerst <brgerst@...il.com> --- arch/x86/kernel/head_64.S | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 780cd92..22db86a 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -212,8 +212,8 @@ ENTRY(secondary_startup_64) */ lgdt early_gdt_descr(%rip) - /* set up data segments. actually 0 would do too */ - movl $__KERNEL_DS,%eax + /* set up data segments */ + xorl %eax,%eax movl %eax,%ds movl %eax,%ss movl %eax,%es -- 1.6.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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