pgtable.h

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/* pgtable.h: FR-V page table mangling
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([e-mail])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * Derived from:
 *	include/asm-m68knommu/pgtable.h
 *	include/asm-i386/pgtable.h
 */

#ifndef _ASM_PGTABLE_H
#define _ASM_PGTABLE_H

#include <asm/mem-layout.h>
#include <asm/setup.h>
#include <asm/processor.h>

#ifndef __ASSEMBLY__
#include <linux/threads.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
struct vm_area_struct;
#endif

#ifndef __ASSEMBLY__
#if defined(CONFIG_HIGHPTE)
typedef unsigned long pte_addr_t;
#else
typedef pte_t *pte_addr_t;
#endif
#endif

/*****************************************************************************/
/*
 * MMU-less operation case first
 */
#ifndef CONFIG_MMU

#define pgd_present(pgd)	(1)		/* pages are always present on NO_MM */
#define pgd_none(pgd)		(0)
#define pgd_bad(pgd)		(0)
#define pgd_clear(pgdp)
#define kern_addr_valid(addr)	(1)
#define	pmd_offset(a, b)	((void *) 0)

#define PAGE_NONE		__pgprot(0)	/* these mean nothing to NO_MM */
#define PAGE_SHARED		__pgprot(0)	/* these mean nothing to NO_MM */
#define PAGE_COPY		__pgprot(0)	/* these mean nothing to NO_MM */
#define PAGE_READONLY		__pgprot(0)	/* these mean nothing to NO_MM */
#define PAGE_KERNEL		__pgprot(0)	/* these mean nothing to NO_MM */

#define __swp_type(x)		(0)
#define __swp_offset(x)		(0)
#define __swp_entry(typ,off)	((swp_entry_t) { ((typ) | ((off) << 7)) })
#define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
#define __swp_entry_to_pte(x)	((pte_t) { (x).val })

#ifndef __ASSEMBLY__
static inline int pte_file(pte_t pte) { return 0; }
#endif

#define ZERO_PAGE(vaddr)	({ BUG(); NULL; })

#define swapper_pg_dir		((pgd_t *) NULL)

#define pgtable_cache_init()		do {} while (0)
#define arch_enter_lazy_mmu_mode()	do {} while (0)
#define arch_leave_lazy_mmu_mode()	do {} while (0)
#define arch_enter_lazy_cpu_mode()	do {} while (0)
#define arch_leave_lazy_cpu_mode()	do {} while (0)

#else /* !CONFIG_MMU */
/*****************************************************************************/
/*
 * then MMU operation
 */

/*
 * ZERO_PAGE is a global shared page that is always zero: used
 * for zero-mapped memory areas etc..
 */
#ifndef __ASSEMBLY__
extern unsigned long empty_zero_page;
#define ZERO_PAGE(vaddr)	virt_to_page(empty_zero_page)
#endif

/*
 * we use 2-level page tables, folding the PMD (mid-level table) into the PGE (top-level entry)
 * [see Documentation/fujitsu/frv/mmu-layout.txt]
 *
 * Page Directory:
 *  - Size: 16KB
 *  - 64 PGEs per PGD
 *  - Each PGE holds 1 PUD and covers 64MB
 *
 * Page Upper Directory:
 *  - Size: 256B
 *  - 1 PUE per PUD
 *  - Each PUE holds 1 PMD and covers 64MB
 *
 * Page Mid-Level Directory
 *  - Size: 256B
 *  - 1 PME per PMD
 *  - Each PME holds 64 STEs, all of which point to separate chunks of the same Page Table
 *  - All STEs are instantiated at the same time
 *
 * Page Table
 *  - Size: 16KB
 *  - 4096 PTEs per PT
 *  - Each Linux PT is subdivided into 64 FR451 PT's, each of which holds 64 entries
 *
 * Pages
 *  - Size: 4KB
 *
 * total PTEs
 *	= 1 PML4E * 64 PGEs * 1 PUEs * 1 PMEs * 4096 PTEs
 *	= 1 PML4E * 64 PGEs * 64 STEs * 64 PTEs/FR451-PT
 *	= 262144 (or 256 * 1024)
 */
#define PGDIR_SHIFT		26
#define PGDIR_SIZE		(1UL << PGDIR_SHIFT)
#define PGDIR_MASK		(~(PGDIR_SIZE - 1))
#define PTRS_PER_PGD		64

#define PUD_SHIFT		26
#define PTRS_PER_PUD		1
#define PUD_SIZE		(1UL << PUD_SHIFT)
#define PUD_MASK		(~(PUD_SIZE - 1))
#define PUE_SIZE		256

#define PMD_SHIFT		26
#define PMD_SIZE		(1UL << PMD_SHIFT)
#define PMD_MASK		(~(PMD_SIZE - 1))
#define PTRS_PER_PMD		1
#define PME_SIZE		256

#define __frv_PT_SIZE		256

#define PTRS_PER_PTE		4096

#define USER_PGDS_IN_LAST_PML4	(TASK_SIZE / PGDIR_SIZE)
#define FIRST_USER_ADDRESS	0

#define USER_PGD_PTRS		(PAGE_OFFSET >> PGDIR_SHIFT)
#define KERNEL_PGD_PTRS		(PTRS_PER_PGD - USER_PGD_PTRS)

#define TWOLEVEL_PGDIR_SHIFT	26
#define BOOT_USER_PGD_PTRS	(__PAGE_OFFSET >> TWOLEVEL_PGDIR_SHIFT)
#define BOOT_KERNEL_PGD_PTRS	(PTRS_PER_PGD - BOOT_USER_PGD_PTRS)

#ifndef __ASSEMBLY__

extern pgd_t swapper_pg_dir[PTRS_PER_PGD];

#define pte_ERROR(e) \
	printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, (e).pte)
#define pmd_ERROR(e) \
	printk("%s:%d: bad pmd %08lx.\n", __FILE__, __LINE__, pmd_val(e))
#define pud_ERROR(e) \
	printk("%s:%d: bad pud %08lx.\n", __FILE__, __LINE__, pmd_val(pud_val(e)))
#define pgd_ERROR(e) \
	printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pmd_val(pud_val(pgd_val(e))))

/*
 * Certain architectures need to do special things when PTEs
 * within a page table are directly modified.  Thus, the following
 * hook is made available.
 */
#define set_pte(pteptr, pteval)				\
do {							\
	*(pteptr) = (pteval);				\
	asm volatile("dcf %M0" :: "U"(*pteptr));	\
} while(0)
#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)

/*
 * pgd_offset() returns a (pgd_t *)
 * pgd_index() is used get the offset into the pgd page's array of pgd_t's;
 */
#define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address))

/*
 * a shortcut which implies the use of the kernel's pgd, instead
 * of a process's
 */
#define pgd_offset_k(address) pgd_offset(&init_mm, address)

/*
 * The "pgd_xxx()" functions here are trivial for a folded two-level
 * setup: the pud is never bad, and a pud always exists (as it's folded
 * into the pgd entry)
 */
static inline int pgd_none(pgd_t pgd)		{ return 0; }
static inline int pgd_bad(pgd_t pgd)		{ return 0; }
static inline int pgd_present(pgd_t pgd)	{ return 1; }
static inline void pgd_clear(pgd_t *pgd)	{ }

#define pgd_populate(mm, pgd, pud)		do { } while (0)
/*
 * (puds are folded into pgds so this doesn't get actually called,
 * but the define is needed for a generic inline function.)
 */
#define set_pgd(pgdptr, pgdval)				\
do {							\
	memcpy((pgdptr), &(pgdval), sizeof(pgd_t));	\
	asm volatile("dcf %M0" :: "U"(*(pgdptr)));	\
} while(0)

static inline pud_t *pud_offset(pgd_t *pgd, unsigned long address)
{
	return (pud_t *) pgd;
}

#define pgd_page(pgd)				(pud_page((pud_t){ pgd }))
#define pgd_page_vaddr(pgd)			(pud_page_vaddr((pud_t){ pgd }))

/*
 * allocating and freeing a pud is trivial: the 1-entry pud is
 * inside the pgd, so has no extra memory associated with it.
 */
#define pud_alloc_one(mm, address)		NULL
#define pud_free(x)				do { } while (0)
#define __pud_free_tlb(tlb, x)			do { } while (0)

/*
 * The "pud_xxx()" functions here are trivial for a folded two-level
 * setup: the pmd is never bad, and a pmd always exists (as it's folded
 * into the pud entry)
 */
static inline int pud_none(pud_t pud)		{ return 0; }
static inline int pud_bad(pud_t pud)		{ return 0; }
static inline int pud_present(pud_t pud)	{ return 1; }
static inline void pud_clear(pud_t *pud)	{ }

#define pud_populate(mm, pmd, pte)		do { } while (0)

/*
 * (pmds are folded into puds so this doesn't get actually called,
 * but the define is needed for a generic inline function.)
 */
#define set_pud(pudptr, pudval)			set_pmd((pmd_t *)(pudptr), (pmd_t) { pudval })

#define pud_page(pud)				(pmd_page((pmd_t){ pud }))
#define pud_page_vaddr(pud)			(pmd_page_vaddr((pmd_t){ pud }))

/*
 * (pmds are folded into pgds so this doesn't get actually called,
 * but the define is needed for a generic inline function.)
 */
extern void __set_pmd(pmd_t *pmdptr, unsigned long __pmd);

#define set_pmd(pmdptr, pmdval)			\
do {						\
	__set_pmd((pmdptr), (pmdval).ste[0]);	\
} while(0)

#define __pmd_index(address)			0

static inline pmd_t *pmd_offset(pud_t *dir, unsigned long address)
{
	return (pmd_t *) dir + __pmd_index(address);
}

#define pte_same(a, b)		((a).pte == (b).pte)