xen64: register callbacks in arch-independent way

Use callback_op hypercall to register callbacks in a 32/64-bit
independent way (64-bit doesn't need a code segment, but that detail
is hidden in XEN_CALLBACK).

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>
diff --git a/include/asm-x86/xen/hypercall.h b/include/asm-x86/xen/hypercall.h
index d0c5ded..2536664 100644
--- a/include/asm-x86/xen/hypercall.h
+++ b/include/asm-x86/xen/hypercall.h
@@ -226,6 +226,7 @@
 	return _hypercall2(int, stack_switch, ss, esp);
 }
 
+#ifdef CONFIG_X86_32
 static inline int
 HYPERVISOR_set_callbacks(unsigned long event_selector,
 			 unsigned long event_address,
@@ -236,6 +237,17 @@
 			   event_selector, event_address,
 			   failsafe_selector, failsafe_address);
 }
+#else  /* CONFIG_X86_64 */
+static inline int
+HYPERVISOR_set_callbacks(unsigned long event_address,
+			unsigned long failsafe_address,
+			unsigned long syscall_address)
+{
+	return _hypercall3(int, set_callbacks,
+			   event_address, failsafe_address,
+			   syscall_address);
+}
+#endif  /* CONFIG_X86_{32,64} */
 
 static inline int
 HYPERVISOR_callback_op(int cmd, void *arg)