From e04e0a630d8b5c621b3a8e70ff20db737d3a5728 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge <jeremy@goop.org> Date: Wed, 25 Jun 2008 00:19:25 -0400 Subject: [PATCH] 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: Eduardo Habkost <ehabkost@redhat.com> Signed-off-by: Jeremy 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: Ingo Molnar <mingo@elte.hu> --- arch/x86/kernel/entry_64.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index ff15ab55228..6d1101469e9 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -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 */ -- 2.41.3