175 lines
7.0 KiB
C
175 lines
7.0 KiB
C
/* $NetBSD: pte.h,v 1.3 1998/03/18 21:52:02 matthias Exp $ */
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/*
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*
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* Copyright (c) 1997 Charles D. Cranor and Washington University.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgment:
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* This product includes software developed by Charles D. Cranor and
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* Washington University.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* pte.h rewritten by chuck based on the jolitz version, plus random
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* info on the pentium and other processors found on the net. The
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* goal of this rewrite is to provide enough documentation on the MMU
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* hardware that the reader will be able to understand it without having
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* to refer to a hardware manual.
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*
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* Modified for the ns32532 by Matthias Pfaller.
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*/
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#ifndef _NS532_PTE_H_
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#define _NS532_PTE_H_
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/*
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* ns32532 MMU hardware structure:
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*
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* The ns32532 MMU is a two-level MMU which maps 4GB of virtual memory.
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* The pagesize is 4K (4096 [0x1000] bytes).
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*
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* The first level table is called a "page directory" and it contains
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* 1024 page directory entries (PDEs). Each PDE is 4 bytes (an int),
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* so a PD fits in a single 4K page. This page is the page directory
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* page (PDP). Each PDE in a PDP maps 4MB of space (1024 * 4MB = 4GB).
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* A PDE contains the physical address of the second level
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* table: The page table.
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*
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* A page table consists of 1024 page table entries (PTEs). Each PTE is
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* 4 bytes (an int), so a page table also fits in a single 4K page. A 4K
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* page being used as a page table is called a page table page (PTP).
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* Each PTE in a PTP maps one 4K page (1024 * 4K = 4MB). A PTE contains
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* the physical address of the page it maps and some flag bits (described
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* below).
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*
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* The processor has a special register, "ptb0", which points to the
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* the PDP which is currently controlling the mappings of the virtual
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* address space.
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*
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* The following picture shows the translation process for a 4K page:
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*
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* ptb0 register [PA of PDP]
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* |
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* |
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* | bits <31-22> of VA bits <21-12> of VA bits <11-0>
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* | index the PDP (0 - 1023) index the PTP are the page offset
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* | | | |
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* | v | |
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* +--->+----------+ | |
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* | PD Page | PA of v |
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* | |---PTP-------->+------------+ |
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* | 1024 PDE | | page table |--PTE--+ |
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* | entries | | (aka PTP) | | |
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* +----------+ | 1024 PTE | | |
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* | entries | | |
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* +------------+ | |
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* | |
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* bits <31-12> bits <11-0>
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* p h y s i c a l a d d r
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*
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* The ns32532 caches PTEs in a TLB. It is important to flush out old
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* TLB mappings when making a change to a mappings. Writing to the
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* ptb0 register will flush the entire TLB. The ns32532 also has an
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* instruction that will invalidate the mapping of a single page (which
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* is useful if you are changing a single page's mappings because it
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* preserves all the cached TLB entries).
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*
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* As shows, bits 31-12 of the PTE contain PA of the page being mapped.
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* the rest of the PTE is defined as follows:
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* bit# name use
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* 11 n/a available for OS use, hardware ignores it
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* 10 n/a available for OS use, hardware ignores it
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* 9 n/a available for OS use, hardware ignores it
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* 8 M modified page
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* 7 R referenced page
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* 6 CI cache inhibited page
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* 5 n/a reserved
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* 4 n/a reserved
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* 3 n/a reserved
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* 2 U/S user/supervisor bit (0=supervisor only, 1=both u&s)
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* 1 R/W read/write bit (0=read only, 1=read-write)
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* 0 V valid page
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*
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* notes:
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* - Useraccessible pages (U/S == 1) are *always* writable in kernel mode.
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* copyout and friends use the ns32532's dual address space instructions
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* for this reason.
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*/
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#if !defined(_LOCORE)
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/*
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* here we define the data types for PDEs and PTEs
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*/
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typedef u_int32_t pd_entry_t; /* PDE */
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typedef u_int32_t pt_entry_t; /* PTE */
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#endif
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/*
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* now we define various for playing with virtual addresses
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*/
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#define PDSHIFT 22 /* offset of PD index in VA */
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#define NBPD (1 << PDSHIFT) /* # bytes mapped by PD (4MB) */
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#define PDOFSET (NBPD-1) /* mask for non-PD part of VA */
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#if 0 /* not used? */
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#define NPTEPD (NBPD / NBPG) /* # of PTEs in a PD */
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#else
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#define PTES_PER_PTP (NBPD / NBPG) /* # of PTEs in a PTP */
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#endif
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#define PD_MASK 0xffc00000 /* page directory address bits */
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#define PT_MASK 0x003ff000 /* page table address bits */
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/*
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* here we define the bits of the PDE/PTE, as described above:
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*
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* XXXCDC: need to rename these (PG_u == ugly).
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*/
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#define PG_V 0x00000001 /* present */
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#define PG_RO 0x00000000 /* read-only by user and kernel */
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#define PG_RW 0x00000002 /* read-write by user */
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#define PG_u 0x00000004 /* accessible by user */
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#define PG_PROT 0x00000006 /* all protection bits */
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#define PG_N 0x00000040 /* non-cacheable */
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#define PG_U 0x00000080 /* has been used */
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#define PG_M 0x00000100 /* has been modified */
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#define PG_AVAIL1 0x00000200 /* ignored by hardware */
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#define PG_AVAIL2 0x00000400 /* ignored by hardware */
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#define PG_AVAIL3 0x00000800 /* ignored by hardware */
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#define PG_FRAME 0xfffff000 /* page frame mask */
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/*
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* various short-hand protection codes
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*/
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#define PG_KR 0x00000000 /* kernel read-only */
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#define PG_KW 0x00000002 /* kernel read-write */
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#endif /* _NS532_PTE_H_ */
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