pgtable.h

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/*
 * 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 - 1999 by Ralf Baechle at alii
 * Copyright (C) 1999 Silicon Graphics, Inc.
 */
#ifndef _ASM_PGTABLE_H
#define _ASM_PGTABLE_H

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

#ifndef _LANGUAGE_ASSEMBLY

#include <linux/linkage.h>
#include <asm/cachectl.h>
#include <linux/config.h>

/* Cache flushing:
 *
 *  - flush_cache_all() flushes entire cache
 *  - flush_cache_mm(mm) flushes the specified mm context's cache lines
 *  - flush_cache_page(mm, vmaddr) flushes a single page
 *  - flush_cache_range(mm, start, end) flushes a range of pages
 *  - flush_page_to_ram(page) write back kernel page to ram
 */
extern void (*_flush_cache_all)(void);
extern void (*_flush_cache_mm)(struct mm_struct *mm);
extern void (*_flush_cache_range)(struct mm_struct *mm, unsigned long start,
				 unsigned long end);
extern void (*_flush_cache_page)(struct vm_area_struct *vma, unsigned long page);
extern void (*_flush_cache_sigtramp)(unsigned long addr);
extern void (*_flush_page_to_ram)(struct page * page);

#define flush_dcache_page(page)			do { } while (0)

#define flush_cache_all()		_flush_cache_all()
#define flush_cache_mm(mm)		_flush_cache_mm(mm)
#define flush_cache_range(mm,start,end)	_flush_cache_range(mm,start,end)
#define flush_cache_page(vma,page)	_flush_cache_page(vma, page)
#define flush_cache_sigtramp(addr)	_flush_cache_sigtramp(addr)
#define flush_page_to_ram(page)		_flush_page_to_ram(page)

#define flush_icache_range(start, end)	flush_cache_all()

#define flush_icache_page(vma, page)					\
do {									\
	unsigned long addr;						\
	addr = (unsigned long) page_address(page);			\
	_flush_cache_page(vma, addr);					\
} while (0)


/*
 * - add_wired_entry() add a fixed TLB entry, and move wired register
 */
extern void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
			       unsigned long entryhi, unsigned long pagemask);


/* Basically we have the same two-level (which is the logical three level
 * Linux page table layout folded) page tables as the i386.  Some day
 * when we have proper page coloring support we can have a 1% quicker
 * tlb refill handling mechanism, but for now it is a bit slower but
 * works even with the cache aliasing problem the R4k and above have.
 */

#endif /* !defined (_LANGUAGE_ASSEMBLY) */

/* PMD_SHIFT determines the size of the area a second-level page table can map */
#define PMD_SHIFT	22
#define PMD_SIZE	(1UL << PMD_SHIFT)
#define PMD_MASK	(~(PMD_SIZE-1))

/* PGDIR_SHIFT determines what a third-level page table entry can map */
#define PGDIR_SHIFT	22
#define PGDIR_SIZE	(1UL << PGDIR_SHIFT)
#define PGDIR_MASK	(~(PGDIR_SIZE-1))

/* Entries per page directory level: we use two-level, so
 * we don't really have any PMD directory physically.
 */
#define PTRS_PER_PTE	1024
#define PTRS_PER_PMD	1
#define PTRS_PER_PGD	1024
#define USER_PTRS_PER_PGD	(TASK_SIZE/PGDIR_SIZE)
#define FIRST_USER_PGD_NR	0

#define VMALLOC_START     KSEG2
#define VMALLOC_VMADDR(x) ((unsigned long)(x))
#define VMALLOC_END       KSEG3

/* Note that we shift the lower 32bits of each EntryLo[01] entry
 * 6 bits to the left. That way we can convert the PFN into the
 * physical address by a single 'and' operation and gain 6 additional
 * bits for storing information which isn't present in a normal
 * MIPS page table.
 *
 * Similar to the Alpha port, we need to keep track of the ref
 * and mod bits in software.  We have a software "yeah you can read
 * from this page" bit, and a hardware one which actually lets the
 * process read from the page.  On the same token we have a software
 * writable bit and the real hardware one which actually lets the
 * process write to the page, this keeps a mod bit via the hardware
 * dirty bit.
 *
 * Certain revisions of the R4000 and R5000 have a bug where if a
 * certain sequence occurs in the last 3 instructions of an executable
 * page, and the following page is not mapped, the cpu can do
 * unpredictable things.  The code (when it is written) to deal with
 * this problem will be in the update_mmu_cache() code for the r4k.
 */
#define _PAGE_PRESENT               (1<<0)  /* implemented in software */
#define _PAGE_READ                  (1<<1)  /* implemented in software */
#define _PAGE_WRITE                 (1<<2)  /* implemented in software */
#define _PAGE_ACCESSED              (1<<3)  /* implemented in software */
#define _PAGE_MODIFIED              (1<<4)  /* implemented in software */

#if defined(CONFIG_CPU_R3000)

#define _PAGE_GLOBAL                (1<<8)
#define _PAGE_VALID                 (1<<9)
#define _PAGE_SILENT_READ           (1<<9)  /* synonym                 */
#define _PAGE_DIRTY                 (1<<10) /* The MIPS dirty bit      */
#define _PAGE_SILENT_WRITE          (1<<10)
#define _CACHE_UNCACHED             (1<<11) /* R4[0246]00              */
#define _CACHE_MASK                 (1<<11)
#define _CACHE_CACHABLE_NONCOHERENT 0

#else
 
#define _PAGE_R4KBUG                (1<<5)  /* workaround for r4k bug  */
#define _PAGE_GLOBAL                (1<<6)
#define _PAGE_VALID                 (1<<7)
#define _PAGE_SILENT_READ           (1<<7)  /* synonym                 */
#define _PAGE_DIRTY                 (1<<8)  /* The MIPS dirty bit      */
#define _PAGE_SILENT_WRITE          (1<<8)
#define _CACHE_CACHABLE_NO_WA       (0<<9)  /* R4600 only              */
#define _CACHE_CACHABLE_WA          (1<<9)  /* R4600 only              */
#define _CACHE_UNCACHED             (2<<9)  /* R4[0246]00              */
#define _CACHE_CACHABLE_NONCOHERENT (3<<9)  /* R4[0246]00              */
#define _CACHE_CACHABLE_CE          (4<<9)  /* R4[04]00 only           */
#define _CACHE_CACHABLE_COW         (5<<9)  /* R4[04]00 only           */
#define _CACHE_CACHABLE_CUW         (6<<9)  /* R4[04]00 only           */
#define _CACHE_CACHABLE_ACCELERATED (7<<9)  /* R10000 only             */
#define _CACHE_MASK                 (7<<9)

#endif

#define __READABLE	(_PAGE_READ | _PAGE_SILENT_READ | _PAGE_ACCESSED)
#define __WRITEABLE	(_PAGE_WRITE | _PAGE_SILENT_WRITE | _PAGE_MODIFIED)

#define _PAGE_CHG_MASK  (PAGE_MASK | _PAGE_ACCESSED | _PAGE_MODIFIED | _CACHE_MASK)

#define PAGE_NONE	__pgprot(_PAGE_PRESENT | _CACHE_CACHABLE_NONCOHERENT)
#define PAGE_SHARED     __pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
			_CACHE_CACHABLE_NONCOHERENT)
#define PAGE_COPY       __pgprot(_PAGE_PRESENT | _PAGE_READ | \
			_CACHE_CACHABLE_NONCOHERENT)
#define PAGE_READONLY   __pgprot(_PAGE_PRESENT | _PAGE_READ | \
			_CACHE_CACHABLE_NONCOHERENT)
#define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \
			_CACHE_CACHABLE_NONCOHERENT)
#define PAGE_USERIO     __pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
			_CACHE_UNCACHED)
#define PAGE_KERNEL_UNCACHED __pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \
			_CACHE_UNCACHED)

/*
 * MIPS can't do page protection for execute, and considers that the same like
 * read. Also, write permissions imply read permissions. This is the closest
 * we can get by reasonable means..
 */
#define __P000	PAGE_NONE
#define __P001	PAGE_READONLY
#define __P010	PAGE_COPY
#define __P011	PAGE_COPY
#define __P100	PAGE_READONLY
#define __P101	PAGE_READONLY
#define __P110	PAGE_COPY
#define __P111	PAGE_COPY

#define __S000	PAGE_NONE
#define __S001	PAGE_READONLY
#define __S010	PAGE_SHARED
#define __S011	PAGE_SHARED
#define __S100	PAGE_READONLY
#define __S101	PAGE_READONLY
#define __S110	PAGE_SHARED
#define __S111	PAGE_SHARED

#if !defined (_LANGUAGE_ASSEMBLY)

#define pte_ERROR(e) \
	printk("%s:%d: bad pte %016lx.\n", __FILE__, __LINE__, pte_val(e))
#define pmd_ERROR(e) \
	printk("%s:%d: bad pmd %016lx.\n", __FILE__, __LINE__, pmd_val(e))
#define pgd_ERROR(e) \
	printk("%s:%d: bad pgd %016lx.\n", __FILE__, __LINE__, pgd_val(e))

/*
 * BAD_PAGETABLE is used when we need a bogus page-table, while
 * BAD_PAGE is used for a bogus page.
 *
 * ZERO_PAGE is a global shared page that is always zero: used
 * for zero-mapped memory areas etc..
 */
extern pte_t __bad_page(void);
extern pte_t *__bad_pagetable(void);

extern unsigned long empty_zero_page;
extern unsigned long zero_page_mask;

#define BAD_PAGETABLE __bad_pagetable()
#define BAD_PAGE __bad_page()
#define ZERO_PAGE(vaddr) \
	(virt_to_page(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask)))

/* number of bits that fit into a memory pointer */
#define BITS_PER_PTR			(8*sizeof(unsigned long))

/* to align the pointer to a pointer address */
#define PTR_MASK			(~(sizeof(void*)-1))

/*
 * sizeof(void*) == (1 << SIZEOF_PTR_LOG2)
 */
#define SIZEOF_PTR_LOG2			2

/* to find an entry in a page-table */
#define PAGE_PTR(address) \
((unsigned long)(address)>>(PAGE_SHIFT-SIZEOF_PTR_LOG2)&PTR_MASK&~PAGE_MASK)

extern void load_pgd(unsigned long pg_dir);

extern pmd_t invalid_pte_table[PAGE_SIZE/sizeof(pmd_t)];

/*
 * Conversion functions: convert a page and protection to a page entry,
 * and a page entry and page directory to the page they refer to.
 */
extern inline unsigned long pmd_page(pmd_t pmd)
{
	return pmd_val(pmd);
}

extern inline void pmd_set(pmd_t * pmdp, pte_t * ptep)
{
	pmd_val(*pmdp) = (((unsigned long) ptep) & PAGE_MASK);
}

extern inline int pte_none(pte_t pte)    { return !pte_val(pte); }
extern inline int pte_present(pte_t pte) { return pte_val(pte) & _PAGE_PRESENT; }

/* Certain architectures need to do special things when pte's
 * within a page table are directly modified.  Thus, the following
 * hook is made available.
 */
extern inline void set_pte(pte_t *ptep, pte_t pteval)
{
	*ptep = pteval;
}

extern inline void pte_clear(pte_t *ptep)
{
	set_pte(ptep, __pte(0));
}

/*
 * Empty pgd/pmd entries point to the invalid_pte_table.
 */
extern inline int pmd_none(pmd_t pmd)
{
	return pmd_val(pmd) == (unsigned long) invalid_pte_table;
}

extern inline int pmd_bad(pmd_t pmd)
{
	return ((pmd_page(pmd) > (unsigned long) high_memory) ||
	        (pmd_page(pmd) < PAGE_OFFSET));
}

extern inline int pmd_present(pmd_t pmd)
{
	return pmd_val(pmd);
}

extern inline void pmd_clear(pmd_t *pmdp)
{
	pmd_val(*pmdp) = ((unsigned long) invalid_pte_table);
}

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

/*
 * Permanent address of a page.  On MIPS64 we never have highmem, so this
 * is simple.
 */
#define page_address(page)	((page)->virtual)
#define pte_page(x)		(mem_map+(unsigned long)((pte_val(x) >> PAGE_SHIFT)))

/*
 * The following only work if pte_present() is true.
 * Undefined behaviour if not..
 */
extern inline int pte_read(pte_t pte)	{ return pte_val(pte) & _PAGE_READ; }
extern inline int pte_write(pte_t pte)	{ return pte_val(pte) & _PAGE_WRITE; }
extern inline int pte_dirty(pte_t pte)	{ return pte_val(pte) & _PAGE_MODIFIED; }
extern inline int pte_young(pte_t pte)	{ return pte_val(pte) & _PAGE_ACCESSED; }

extern inline pte_t pte_wrprotect(pte_t pte)
{
	pte_val(pte) &= ~(_PAGE_WRITE | _PAGE_SILENT_WRITE);
	return pte;
}

extern inline pte_t pte_rdprotect(pte_t pte)
{
	pte_val(pte) &= ~(_PAGE_READ | _PAGE_SILENT_READ);
	return pte;
}

extern inline pte_t pte_mkclean(pte_t pte)
{
	pte_val(pte) &= ~(_PAGE_MODIFIED|_PAGE_SILENT_WRITE);
	return pte;
}

extern inline pte_t pte_mkold(pte_t pte)
{
	pte_val(pte) &= ~(_PAGE_ACCESSED|_PAGE_SILENT_READ);
	return pte;
}

extern inline pte_t pte_mkwrite(pte_t pte)
{
	pte_val(pte) |= _PAGE_WRITE;
	if (pte_val(pte) & _PAGE_MODIFIED)
		pte_val(pte) |= _PAGE_SILENT_WRITE;
	return pte;
}

extern inline pte_t pte_mkread(pte_t pte)
{
	pte_val(pte) |= _PAGE_READ;
	if (pte_val(pte) & _PAGE_ACCESSED)
		pte_val(pte) |= _PAGE_SILENT_READ;
	return pte;
}

extern inline pte_t pte_mkdirty(pte_t pte)