loader/i386/bsd_pagetable.c

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (c) 1998  Michael Smith <msmith@freebsd.org>
   4  *  Copyright (C) 2009  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 /* Based on the code from FreeBSD originally distributed under the
  21    following terms: */
  22
  23 /*-
  24  * Copyright (c) 1998  Michael Smith <msmith@freebsd.org>
  25  * All rights reserved.
  26  *
  27  * Redistribution and use in source and binary forms, with or without
  28  * modification, are permitted provided that the following conditions
  29  * are met:
  30  * 1. Redistributions of source code must retain the above copyright
  31  *    notice, this list of conditions and the following disclaimer.
  32  * 2. Redistributions in binary form must reproduce the above copyright
  33  *    notice, this list of conditions and the following disclaimer in the
  34  *    documentation and/or other materials provided with the distribution.
  35  *
  36  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  37  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  38  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  39  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  40  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  41  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  42  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  44  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  45  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  46  * SUCH DAMAGE.
  47  *
  48  * $FreeBSD$
  49  */
  50
  51
  52 static void
  53 fill_bsd64_pagetable (grub_uint8_t *target)
  54 {
  55   grub_uint64_t *pt2, *pt3, *pt4;
  56   int i;
  57
  58 #define PG_V            0x001
  59 #define PG_RW           0x002
  60 #define PG_U            0x004
  61 #define PG_PS           0x080
  62
  63   pt4 = (grub_uint64_t *) target;
  64   pt3 = (grub_uint64_t *) (target + 4096);
  65   pt2 = (grub_uint64_t *) (target + 8192);
  66
  67   grub_memset ((char *) target, 0, 4096 * 3);
  68
  69   /*
  70    * This is kinda brutal, but every single 1GB VM memory segment points to
  71    * the same first 1GB of physical memory.  But it is how BSD expects
  72    * it to be.
  73    */
  74   for (i = 0; i < 512; i++)
  75     {
  76       /* Each slot of the level 4 pages points to the same level 3 page */
  77       pt4[i] = (grub_addr_t) &pt3[0];
  78       pt4[i] |= PG_V | PG_RW | PG_U;
  79
  80       /* Each slot of the level 3 pages points to the same level 2 page */
  81       pt3[i] = (grub_addr_t) &pt2[0];
  82       pt3[i] |= PG_V | PG_RW | PG_U;
  83
  84       /* The level 2 page slots are mapped with 2MB pages for 1GB. */
  85       pt2[i] = i * (2 * 1024 * 1024);
  86       pt2[i] |= PG_V | PG_RW | PG_PS | PG_U;
  87     }
  88 }