xen64: deal with extra words Xen pushes onto exception frames

Xen pushes two extra words containing the values of rcx and r11.  This
pvop hook copies the words back into their appropriate registers, and
cleans them off the stack.  This leaves the stack in native form, so
the normal handler can run unchanged.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.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>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index 4ec10827370b..b147b495daef 100644
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -133,6 +133,11 @@ check_events:
         ret
 #endif
 
+ENTRY(xen_adjust_exception_frame)
+        mov 8+0(%rsp),%rcx
+        mov 8+8(%rsp),%r11
+        ret $16
+
 ENTRY(xen_iret)
         pushq $0
         jmp hypercall_page + __HYPERVISOR_iret * 32