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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 - 2002 by Ralf Baechle
* Copyright (C) 1999, 2000, 2001 Silicon Graphics, Inc.
* Copyright (C) 2002 Maciej W. Rozycki
*/
#ifndef _ASM_PGTABLE_BITS_H
#define _ASM_PGTABLE_BITS_H
/*
* 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 */
#define _PAGE_FILE (1<<4) /* set:pagecache unset:swap */
#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)
#define _CACHE_MASK (1<<11)
/*
* Cache attributes
*/
#define _CACHE_CACHABLE_NONCOHERENT 0
#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)
#endif /* _ASM_PGTABLE_BITS_H */
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