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Commit e04e0a63 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
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x86: use __KERNEL_DS as SS when returning to a kernel thread 



This is needed when the kernel is running on RING3, such as under Xen.
x86_64 has a weird feature that makes it #GP on iret when SS is a null
descriptor.

This need to be tested on bare metal to make sure it doesn't cause any
problems. AMD specs say SS is always ignored (except on iret?).

Signed-off-by: default avatarEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 478de5a9

arch/x86/kernel/entry_64.S

+1 −1
Original line number Diff line number Diff line
@@ -104,7 +104,7 @@ ENTRY(native_irq_enable_syscall_ret) 
	.macro FAKE_STACK_FRAME child_rip

	/* push in order ss, rsp, eflags, cs, rip */

	xorl %eax, %eax

	pushq %rax /* ss */

	pushq $__KERNEL_DS /* ss */

	CFI_ADJUST_CFA_OFFSET	8

	/*CFI_REL_OFFSET	ss,0*/

	pushq %rax /* rsp */