kernel/include/paging.h

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2007  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   4  *  Copyright (C) 2008  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   5  *
   6  *  This program 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  *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20
  21 #ifndef _PAGING_H
  22 #define _PAGING_H
  23
  24 #include <build.h>
  25
  26 /* x86 dependent */
  27 #ifdef ARCH_i386
  28
  29 #define PAGE_MEM_LOW            0x400000        // 0-4MB for kernel stuff
  30 #define PAGE_MEM_FB             0x500000        // 4-5MB for framebuffer
  31 #define PAGE_MEM_HIGH           0x800000        // 5-8MB for storage (binaries, additional data)
  32
  33 #define PAGING_BIT              0x80000000
  34
  35 #define PAGE_ATTR_MAPPED        3
  36 #define PAGE_ATTR_UNMAPPED      2
  37
  38 #define PAGE_TABLE_FLAG_FREE    0x1
  39 #define PAGE_TABLE_FLAG_KERNEL  0x2
  40 #define PAGE_TABLE_FLAG_USER    0x4
  41
  42 #define PAGE_TABLE_BLOCK_SIZE   4096            // 4kB
  43 #define PAGE_DIR_BLOCK_SIZE     1024            // 4kB * 1024 = 4MB
  44
  45 // Macros used in the bitset algorithms.
  46 #define index_from_bit(a) (a/(8*4))
  47 #define offset_from_bit(a) (a%(8*4))
  48
  49 #endif
  50
  51 /* Page structure */
  52 typedef struct page_context
  53 {
  54         unsigned present : 1;
  55         unsigned rw : 1;
  56         unsigned user : 1;
  57         unsigned accessed : 1;
  58         unsigned dirty : 1;
  59         unsigned unused : 7;
  60         unsigned frame : 20;
  61 } page_t;
  62
  63 typedef struct page_table_context
  64 {
  65         page_t pages[1024];
  66 } page_table_t;
  67
  68 typedef struct page_dir_context
  69 {
  70         page_table_t *tables[1024];
  71         unsigned tables_phys[1024];
  72         unsigned addr_phys;
  73 } page_dir_t;
  74
  75 typedef struct page_entity_context
  76 {
  77         page_dir_t *page_dir;
  78         unsigned *frames;
  79 } page_ent_t;
  80
  81 /* externs */
  82 extern unsigned int init_paging ();
  83 extern unsigned paging_enable ();
  84 extern unsigned paging_disable ();
  85 extern page_ent_t *page_cover_create ();
  86 extern unsigned page_cover_delete (page_ent_t *page_cover);
  87 extern unsigned page_mmap (page_ent_t *page_cover, void *from, void *to, unsigned kernel, unsigned writeable);
  88 extern unsigned page_unmmap (page_ent_t *page_cover, void *from, void *to);
  89 extern void page_dir_switch (page_dir_t *page_dir);
  90
  91 #endif
  92