[PATCH] powerpc: Add a is_kernel_addr() macro

There's a bunch of code that compares an address with KERNELBASE to see if
it's a "kernel address", ie. >= KERNELBASE. The proper test is actually to
compare with PAGE_OFFSET, since we're going to change KERNELBASE soon.

So replace all of them with an is_kernel_addr() macro that does that.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 60e852f..a47b273 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -134,14 +134,14 @@
 	else
 		unmapped_base = TASK_UNMAPPED_BASE_USER64;
 
-	if (pc >= KERNELBASE)
+	if (is_kernel_addr(pc))
 		return;
 	slb_allocate(pc);
 
 	if (GET_ESID(pc) == GET_ESID(stack))
 		return;
 
-	if (stack >= KERNELBASE)
+	if (is_kernel_addr(stack))
 		return;
 	slb_allocate(stack);
 
@@ -149,7 +149,7 @@
 	    || (GET_ESID(stack) == GET_ESID(unmapped_base)))
 		return;
 
-	if (unmapped_base >= KERNELBASE)
+	if (is_kernel_addr(unmapped_base))
 		return;
 	slb_allocate(unmapped_base);
 }