Commit 8ec6993d authored Nov 25, 2009 by Brian Gerst Committed by Ingo Molnar Nov 26, 2009

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@gmail.com>
Cc: Tim Blechmann <tim@klingt.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jan Beulich <JBeulich@novell.com>
LKML-Reference: <1259165856-3512-1-git-send-email-brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 64b028b2

arch/x86/kernel/head_64.S

+2 −2

Original line number	Diff line number	Diff line
		@@ -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