LCOM1920-T02G10

/*        $NetBSD: pte.h,v 1.27 2011/02/01 20:09:08 chuck Exp $        */

/*

 * Copyright (c) 2001 Wasabi Systems, Inc.

 * All rights reserved.

 *

 * Written by Frank van der Linden for Wasabi Systems, Inc.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *      This product includes software developed for the NetBSD Project by

 *      Wasabi Systems, Inc.

 * 4. The name of Wasabi Systems, Inc. may not be used to endorse

 *    or promote products derived from this software without specific prior

 *    written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC

 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGE.

 */

/*

 * Copyright (c) 1997 Charles D. Cranor and Washington University.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/*

 * pte.h rewritten by chuck based on the jolitz version, plus random

 * info on the pentium and other processors found on the net.   the

 * goal of this rewrite is to provide enough documentation on the MMU

 * hardware that the reader will be able to understand it without having

 * to refer to a hardware manual.

 */

#ifndef _I386_PTE_H_

#define _I386_PTE_H_

#ifdef _KERNEL_OPT

#include "opt_xen.h"

#endif

/*

 * i386 MMU hardware structure (without PAE extension):

 *

 * the i386 MMU is a two-level MMU which maps 4GB of virtual memory.

 * the pagesize is 4K (4096 [0x1000] bytes), although newer pentium

 * processors can support a 4MB pagesize as well.

 *

 * the first level table (segment table?) is called a "page directory"

 * and it contains 1024 page directory entries (PDEs).   each PDE is

 * 4 bytes (an int), so a PD fits in a single 4K page.   this page is

 * the page directory page (PDP).  each PDE in a PDP maps 4MB of space 

 * (1024 * 4MB = 4GB).   a PDE contains the physical address of the 

 * second level table: the page table.   or, if 4MB pages are being used,

 * then the PDE contains the PA of the 4MB page being mapped.

 *

 * a page table consists of 1024 page table entries (PTEs).  each PTE is

 * 4 bytes (an int), so a page table also fits in a single 4K page.  a

 * 4K page being used as a page table is called a page table page (PTP).

 * each PTE in a PTP maps one 4K page (1024 * 4K = 4MB).   a PTE contains

 * the physical address of the page it maps and some flag bits (described

 * below).

 * 

 * the processor has a special register, "cr3", which points to the

 * the PDP which is currently controlling the mappings of the virtual

 * address space.

 *

 * the following picture shows the translation process for a 4K page:

 *

 * %cr3 register [PA of PDP]

 *      |

 *      |

 *      |   bits <31-22> of VA         bits <21-12> of VA   bits <11-0>

 *      |   index the PDP (0 - 1023)   index the PTP        are the page offset

 *      |         |                           |                  |

 *      |         v                           |                  |

 *      +--->+----------+                     |                  |

 *           | PD Page  |   PA of             v                  |

 *           |          |---PTP-------->+------------+           |

 *           | 1024 PDE |               | page table |--PTE--+   |

 *           | entries  |               | (aka PTP)  |       |   |

 *           +----------+               | 1024 PTE   |       |   |

 *                                      | entries    |       |   |

 *                                      +------------+       |   |

 *                                                           |   |

 *                                                bits <31-12>   bits <11-0>

 *                                                p h y s i c a l  a d d r

 *

 * the i386 caches PTEs in a TLB.   it is important to flush out old

 * TLB mappings when making a change to a mappings.   writing to the 

 * %cr3 will flush the entire TLB.    newer processors also have an

 * instruction that will invalidate the mapping of a single page (which

 * is useful if you are changing a single mappings because it preserves

 * all the cached TLB entries).

 *

 * as shows, bits 31-12 of the PTE contain PA of the page being mapped.

 * the rest of the PTE is defined as follows:

 *   bit#        name        use

 *   11                n/a        available for OS use, hardware ignores it

 *   10                n/a        available for OS use, hardware ignores it

 *   9                n/a        available for OS use, hardware ignores it

 *   8                G        global bit (see discussion below)

 *   7                PS        page size [for PDEs] (0=4k, 1=4M <if supported>) 

 *   6                D        dirty (modified) page

 *   5                A        accessed (referenced) page

 *   4                PCD        cache disable

 *   3                PWT        prevent write through (cache)

 *   2                U/S        user/supervisor bit (0=supervisor only, 1=both u&s)

 *   1                R/W        read/write bit (0=read only, 1=read-write)

 *   0                P        present (valid)

 *

 * notes: 

 *  - PS is only supported on newer processors

 *  - PTEs with the G bit are global in the sense that they are not 

 *    flushed from the TLB when %cr3 is written (to flush, use the 

 *    "flush single page" instruction).   this is only supported on

 *    newer processors.    this bit can be used to keep the kernel's

 *    TLB entries around while context switching.   since the kernel

 *    is mapped into all processes at the same place it does not make 

 *    sense to flush these entries when switching from one process'

 *    pmap to another.

 *

 * The PAE extension extends the size of the PTE to 64 bits (52bits physical

 * address) and is compatible with the amd64 PTE format. The first level

 * maps 2M, the second 1G, so a third level page table is introduced to

 * map the 4GB virtual address space. This PD has only 4 entries.

 * We can't use recursive mapping at level 3 to map the PD pages, as this

 * would eat one GB of address space. In addition, Xen imposes restrictions

 * on the entries we put in the L3 page (for example, the page pointed to by

 * the last slot can't be shared among different L3 pages), which makes 

 * handling this L3 page in the same way we do for L2 on i386 (or L4 on amd64)

 * difficult. For most things we'll just pretend to have only 2 levels,

 * with the 2 high bits of the L2 index being in fact the index in the

 * L3.

 */

#if !defined(_LOCORE)

/*

 * here we define the data types for PDEs and PTEs

 */

#ifdef PAE

typedef uint64_t pd_entry_t;                /* PDE */

typedef uint64_t pt_entry_t;                /* PTE */

#else

typedef uint32_t pd_entry_t;                /* PDE */

typedef uint32_t pt_entry_t;                /* PTE */

#endif

#endif

/*

 * now we define various for playing with virtual addresses

 */

#ifdef PAE

#define        L1_SHIFT        12

#define        L2_SHIFT        21

#define        L3_SHIFT        30

#define        NBPD_L1                (1ULL << L1_SHIFT) /* # bytes mapped by L1 ent (4K) */

#define        NBPD_L2                (1ULL << L2_SHIFT) /* # bytes mapped by L2 ent (2MB) */

#define        NBPD_L3                (1ULL << L3_SHIFT) /* # bytes mapped by L3 ent (1GB) */

#define        L3_MASK                0xc0000000

#define        L2_REALMASK        0x3fe00000

#define        L2_MASK                (L2_REALMASK | L3_MASK)

#define        L1_MASK                0x001ff000

#define        L3_FRAME        (L3_MASK)

#define        L2_FRAME        (L3_FRAME | L2_MASK)

#define        L1_FRAME        (L2_FRAME|L1_MASK)

#define        PG_FRAME        0x000ffffffffff000ULL /* page frame mask */

#define        PG_LGFRAME        0x000fffffffe00000ULL /* large (2MB) page frame mask */

/* macros to get real L2 and L3 index, from our "extended" L2 index */

#define l2tol3(idx)        ((idx) >> (L3_SHIFT - L2_SHIFT))

#define l2tol2(idx)        ((idx) & (L2_REALMASK >>  L2_SHIFT))

#else /* PAE */

#define        L1_SHIFT        12

#define        L2_SHIFT        22

#define        NBPD_L1                (1UL << L1_SHIFT) /* # bytes mapped by L1 ent (4K) */

#define        NBPD_L2                (1UL << L2_SHIFT) /* # bytes mapped by L2 ent (4MB) */

#define L2_MASK                0xffc00000

#define L1_MASK                0x003ff000

#define L2_FRAME        (L2_MASK)

#define L1_FRAME        (L2_FRAME|L1_MASK)

#define        PG_FRAME        0xfffff000        /* page frame mask */

#define        PG_LGFRAME        0xffc00000        /* large (4MB) page frame mask */

#endif /* PAE */

/*

 * here we define the bits of the PDE/PTE, as described above:

 *

 * XXXCDC: need to rename these (PG_u == ugly).

 */

#define        PG_V                0x00000001        /* valid entry */

#define        PG_RO                0x00000000        /* read-only page */

#define        PG_RW                0x00000002        /* read-write page */

#define        PG_u                0x00000004        /* user accessible page */

#define        PG_PROT                0x00000806        /* all protection bits */

#define PG_WT                0x00000008        /* write through */

#define        PG_N                0x00000010        /* non-cacheable */

#define        PG_U                0x00000020        /* has been used */

#define        PG_M                0x00000040        /* has been modified */

#define PG_PAT                0x00000080        /* PAT (on pte) */

#define PG_PS                0x00000080        /* 4MB page size (2MB for PAE) */

#define PG_G                0x00000100        /* global, don't TLB flush */

#define PG_AVAIL1        0x00000200        /* ignored by hardware */

#define PG_AVAIL2        0x00000400        /* ignored by hardware */

#define PG_AVAIL3        0x00000800        /* ignored by hardware */

#define PG_LGPAT        0x00001000        /* PAT on large pages */

/*

 * various short-hand protection codes

 */

#define        PG_KR                0x00000000        /* kernel read-only */

#define        PG_KW                0x00000002        /* kernel read-write */

#ifdef PAE

#define        PG_NX                0x8000000000000000ULL /* No-execute */

#else

#define        PG_NX                0                /* dummy */

#endif

#include <x86/pte.h>

#endif /* _I386_PTE_H_ */