UBUNTU: SAUCE: powerpc: add osb barrier

CVE-2017-5753 (Spectre v1 Intel)
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/powerpc/include/asm/barrier.h

@@ -36,6 +36,8 @@
 
 #define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } while (0)
 
+#define osb()   asm volatile("ori 31,31,0")
+
 #ifdef __SUBARCH_HAS_LWSYNC
 #    define SMPWMB      LWSYNC
 #else