x86, extable: Remove open-coded exception table entries in arch/x86/xen/xen-asm_32.S

Remove open-coded exception table entries in arch/x86/xen/xen-asm_32.S,
and replace them with _ASM_EXTABLE() macros; this will allow us to
change the format and type of the exception table entries.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/CA%2B55aFyijf43qSu3N9nWHEBwaGbb7T2Oq9A=9EyR=Jtyqfq_cQ@mail.gmail.com

arch/x86/xen/xen-asm_32.S

@@ -14,6 +14,7 @@
 #include <asm/thread_info.h>
 #include <asm/processor-flags.h>
 #include <asm/segment.h>
+#include <asm/asm.h>
 
 #include <xen/interface/xen.h>
 
@@ -137,10 +138,7 @@ iret_restore_end:
 
 1:	iret
 xen_iret_end_crit:
-.section __ex_table, "a"
-	.align 4
-	.long 1b, iret_exc
-.previous
+	_ASM_EXTABLE(1b, iret_exc)
 
 hyper_iret:
 	/* put this out of line since its very rarely used */