UBUNTU: SAUCE: rfi-flush: Fallback flush add load dependency

CVE-2017-5754

BugLink: http://bugs.launchpad.net/bugs/1742772

Add a data dependency on loads for the fallback flush. This
reduces or eliminates instances of incomplete flushing on P8 and
P9.
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>

arch/powerpc/kernel/exceptions-64s.S

@@ -748,8 +748,8 @@ rfi_flush_fallback:
 	.rept	8 /* 8-way set associative */
 	ldx	r11,r10,r8
 	add	r8,r8,r12
+	add	r8,r8,r11 /* r11 will be 0, but this creates a dependency */
 	.endr
-	lwsync	/* Ensure that we do all 8 sets before others */
 	addi	r10,r10,128 /* 128 byte cache line */
 	bdnz	1b
 
@@ -790,8 +790,8 @@ hrfi_flush_fallback:
 	.rept	8 /* 8-way set associative */
 	ldx	r11,r10,r8
 	add	r8,r8,r12
+	add	r8,r8,r11 /* r11 will be 0, but this creates a dependency */
 	.endr
-	lwsync	/* Ensure that we do all 8 sets before others */
 	addi	r10,r10,128 /* 128 byte cache line */
 	bdnz	1b