powerpc: Fix booke hugetlb preload code for PPC_MM_SLICES and 64-bit

This patch does 2 things: It corrects the code that determines the
size to write into MAS1 for the PPC_MM_SLICES case (this originally
came from David Gibson and I had incorrectly altered it), and it
changes the methodolody used to calculate the size for !PPC_MM_SLICES
to work for 64-bit as well as 32-bit.

Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/mm/hugetlbpage-book3e.c

@@ -45,23 +45,20 @@ void book3e_hugetlb_preload(struct mm_struct *mm, unsigned long ea, pte_t pte)
 	unsigned long flags;
 
 #ifdef CONFIG_PPC_FSL_BOOK3E
-	int index, lz, ncams;
-	struct vm_area_struct *vma;
+	int index, ncams;
 #endif
 
 	if (unlikely(is_kernel_addr(ea)))
 		return;
 
 #ifdef CONFIG_PPC_MM_SLICES
-	psize = mmu_get_tsize(get_slice_psize(mm, ea));
-	tsize = mmu_get_psize(psize);
+	psize = get_slice_psize(mm, ea);
+	tsize = mmu_get_tsize(psize);
 	shift = mmu_psize_defs[psize].shift;
 #else
-	vma = find_vma(mm, ea);
-	psize = vma_mmu_pagesize(vma);	/* returns actual size in bytes */
-	asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (psize));
-	shift = 31 - lz;
-	tsize = 21 - lz;
+	psize = vma_mmu_pagesize(find_vma(mm, ea));
+	shift = __ilog2(psize);
+	tsize = shift - 10;
 #endif
 
 	/*