arm64: Handle 4 level page table for swapper

At the moment, we only support maximum of 3-level page table for
swapper. With 48bit VA, 64K has only 3 levels and 4K uses section
mapping. Add support for 4-level page table for swapper, needed
by 16K pages.

Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/head.S

@@ -271,7 +271,10 @@ ENDPROC(preserve_boot_args)
  */
 	.macro	create_pgd_entry, tbl, virt, tmp1, tmp2
 	create_table_entry \tbl, \virt, PGDIR_SHIFT, PTRS_PER_PGD, \tmp1, \tmp2
-#if SWAPPER_PGTABLE_LEVELS == 3
+#if SWAPPER_PGTABLE_LEVELS > 3
+	create_table_entry \tbl, \virt, PUD_SHIFT, PTRS_PER_PUD, \tmp1, \tmp2
+#endif
+#if SWAPPER_PGTABLE_LEVELS > 2
 	create_table_entry \tbl, \virt, SWAPPER_TABLE_SHIFT, PTRS_PER_PTE, \tmp1, \tmp2
 #endif
 	.endm