[PATCH] powerpc: Replace VMALLOCBASE with VMALLOC_START

On ppc64, we independently define VMALLOCBASE and VMALLOC_START to be
the same thing: the start of the vmalloc() area at 0xd000000000000000.
VMALLOC_START is used much more widely, including in generic code, so
this patch gets rid of the extraneous VMALLOCBASE.

This does require moving the definitions of region IDs from page_64.h
to pgtable.h, but they don't clearly belong in the former rather than
the latter, anyway.  While we're moving them, clean up the definitions
of the REGION_IDs:
	- Abolish REGION_SIZE, it was only used once, to define
REGION_MASK anyway
	- Define the specific region ids in terms of the REGION_ID()
macro.
	- Define KERNEL_REGION_ID in terms of PAGE_OFFSET rather than
KERNELBASE.  It amounts to the same thing, but conceptually this is
about the region of the linear mapping (which starts at PAGE_OFFSET)
rather than of the kernel text itself (which is at KERNELBASE).

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

include/asm-powerpc/pgtable.h

@@ -57,6 +57,17 @@ struct mm_struct;
 #define IMALLOC_BASE	(PHBS_IO_BASE + 0x80000000ul)	/* Reserve 2 gigs for PHBs */
 #define IMALLOC_END	(VMALLOC_START + PGTABLE_RANGE)
 
+/*
+ * Region IDs
+ */
+#define REGION_SHIFT		60UL
+#define REGION_MASK		(0xfUL << REGION_SHIFT)
+#define REGION_ID(ea)		(((unsigned long)(ea)) >> REGION_SHIFT)
+
+#define VMALLOC_REGION_ID	(REGION_ID(VMALLOC_START))
+#define KERNEL_REGION_ID	(REGION_ID(PAGE_OFFSET))
+#define USER_REGION_ID		(0UL)
+
 /*
  * Common bits in a linux-style PTE.  These match the bits in the
  * (hardware-defined) PowerPC PTE as closely as possible. Additional