x86-64: Fix CFI data for common_interrupt()

Commit eab9e6137f23 ("x86-64: Fix CFI data for interrupt frames")
introduced a DW_CFA_def_cfa_expression in the SAVE_ARGS_IRQ
macro. To later define the CFA using a simple register+offset
rule both register and offset need to be supplied. Just using
CFI_DEF_CFA_REGISTER leaves the offset undefined. So use
CFI_DEF_CFA with reg+off explicitly at the end of
common_interrupt.

Signed-off-by: Mark Wielaard <mjw@redhat.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/1330079527-30711-1-git-send-email-mjw@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/entry_64.S

@@ -813,7 +813,7 @@ ret_from_intr:
 
 	/* Restore saved previous stack */
 	popq %rsi
-	CFI_DEF_CFA_REGISTER	rsi
+	CFI_DEF_CFA rsi,SS+8-RBP	/* reg/off reset after def_cfa_expr */
 	leaq ARGOFFSET-RBP(%rsi), %rsp
 	CFI_DEF_CFA_REGISTER	rsp
 	CFI_ADJUST_CFA_OFFSET	RBP-ARGOFFSET