/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1994, 95, 96, 97, 98, 99, 2000, 2003 Ralf Baechle
 * Copyright (C) 1999, 2000, 2001 Silicon Graphics, Inc.
 */
#ifndef _ASM_PGTABLE_64_H
#define _ASM_PGTABLE_64_H

#include <linux/compiler.h>
#include <linux/linkage.h>

#include <asm/addrspace.h>
#include <asm/page.h>
#include <asm/cachectl.h>
#include <asm/fixmap.h>

#ifdef CONFIG_PAGE_SIZE_64KB
#include <asm-generic/pgtable-nopmd.h>
#else
#include <asm-generic/pgtable-nopud.h>
#endif

/*
 * Each address space has 2 4K pages as its page directory, giving 1024
 * (== PTRS_PER_PGD) 8 byte pointers to pmd tables. Each pmd table is a
 * single 4K page, giving 512 (== PTRS_PER_PMD) 8 byte pointers to page
 * tables. Each page table is also a single 4K page, giving 512 (==
 * PTRS_PER_PTE) 8 byte ptes. Each pud entry is initialized to point to
 * invalid_pmd_table, each pmd entry is initialized to point to
 * invalid_pte_table, each pte is initialized to 0. When memory is low,
 * and a pmd table or a page table allocation fails, empty_bad_pmd_table
 * and empty_bad_page_table is returned back to higher layer code, so
 * that the failure is recognized later on. Linux does not seem to
 * handle these failures very well though. The empty_bad_page_table has
 * invalid pte entries in it, to force page faults.
 *
 * Kernel mappings: kernel mappings are held in the swapper_pg_table.
 * The layout is identical to userspace except it's indexed with the
 * fault address - VMALLOC_START.
 */


/* PGDIR_SHIFT determines what a third-level page table entry can map */
#ifdef __PAGETABLE_PMD_FOLDED
#define PGDIR_SHIFT	(PAGE_SHIFT + PAGE_SHIFT + PTE_ORDER - 3)
#else

/* PMD_SHIFT determines the size of the area a second-level page table can map */
#define PMD_SHIFT	(PAGE_SHIFT + (PAGE_SHIFT + PTE_ORDER - 3))
#define PMD_SIZE	(1UL << PMD_SHIFT)
#define PMD_MASK	(~(PMD_SIZE-1))


#define PGDIR_SHIFT	(PMD_SHIFT + (PAGE_SHIFT + PMD_ORDER - 3))
#endif
#define PGDIR_SIZE	(1UL << PGDIR_SHIFT)
#define PGDIR_MASK	(~(PGDIR_SIZE-1))

/*
 * For 4kB page size we use a 3 level page tree and an 8kB pud, which
 * permits us mapping 40 bits of virtual address space.
 *
 * We used to implement 41 bits by having an order 1 pmd level but that seemed
 * rather pointless.
 *
 * For 8kB page size we use a 3 level page tree which permits a total of
 * 8TB of address space.  Alternatively a 33-bit / 8GB organization using
 * two levels would be easy to implement.
 *
 * For 16kB page size we use a 2 level page tree which permits a total of
 * 36 bits of virtual address space.  We could add a third level but it seems
 * like at the moment there's no need for this.
 *
 * For 64kB page size we use a 2 level page table tree for a total of 42 bits
 * of virtual address space.
 */
#ifdef CONFIG_PAGE_SIZE_4KB
#define PGD_ORDER		1
#define PUD_ORDER		aieeee_attempt_to_allocate_pud
#define PMD_ORDER		0
#define PTE_ORDER		0
#endif
#ifdef CONFIG_PAGE_SIZE_8KB
#define PGD_ORDER		0
#define PUD_ORDER		aieeee_attempt_to_allocate_pud
#define PMD_ORDER		0
#define PTE_ORDER		0
#endif
#ifdef CONFIG_PAGE_SIZE_16KB
#define PGD_ORDER		0
#define PUD_ORDER		aieeee_attempt_to_allocate_pud
#define PMD_ORDER		0
#define PTE_ORDER		0
#endif
#ifdef CONFIG_PAGE_SIZE_32KB
#define PGD_ORDER		0
#define PUD_ORDER		aieeee_attempt_to_allocate_pud
#define PMD_ORDER		0
#define PTE_ORDER		0
#endif
#ifdef CONFIG_PAGE_SIZE_64KB
#define PGD_ORDER		0
#define PUD_ORDER		aieeee_attempt_to_allocate_pud
#define PMD_ORDER		aieeee_attempt_to_allocate_pmd
#define PTE_ORDER		0
#endif

#define PTRS_PER_PGD	((PAGE_SIZE << PGD_ORDER) / sizeof(pgd_t))
#ifndef __PAGETABLE_PMD_FOLDED
#define PTRS_PER_PMD	((PAGE_SIZE << PMD_ORDER) / sizeof(pmd_t))
#endif
#define PTRS_PER_PTE	((PAGE_SIZE << PTE_ORDER) / sizeof(pte_t))

#if PGDIR_SIZE >= TASK_SIZE64
#define USER_PTRS_PER_PGD       (1)
#else
#define USER_PTRS_PER_PGD	(TASK_SIZE64 / PGDIR_SIZE)
#endif