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  1. /*
  2.  * Copyright (c) 2007 Pavel Jancik, Michal Kebrt
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29.  
  30. /** @addtogroup arm32boot
  31.  * @{
  32.  */
  33. /** @file
  34.  */
  35.  
  36.  
  37. #include "mm.h"
  38.  
  39.  
  40. /** Initializes "section" page table entry.
  41.  *
  42.  *  Will be readable/writable by kernel with no access from user mode.
  43.  *  Will belong to domain 0. No cache or buffering is enabled.
  44.  *  
  45.  *  @param pte    Section entry to initialize.
  46.  *  @param frame  First frame in the section (frame number).
  47.  *
  48.  *  @note         If #frame is not 1MB aligned, first lower 1MB aligned frame will be used.
  49.  */  
  50. static void init_pte_level0_section(pte_level0_section_t* pte, unsigned int frame)
  51. {
  52.     pte->descriptor_type   = PTE_DESCRIPTOR_SECTION;
  53.     pte->bufferable        = 0;
  54.     pte->cacheable         = 0;
  55.     pte->impl_specific     = 0;
  56.     pte->domain            = 0;
  57.     pte->should_be_zero_1  = 0;
  58.     pte->access_permission = PTE_AP_USER_NO_KERNEL_RW; 
  59.     pte->should_be_zero_2  = 0;
  60.     pte->section_base_addr = frame;
  61. }
  62.  
  63.  
  64. /** Initializes page table used while booting the kernel. */
  65. static void init_page_table(void)
  66. {
  67.     int i;
  68.     const unsigned int first_kernel_page = ADDR2PFN(PA2KA(0));
  69.  
  70.     // create 1:1 virtual-physical mapping (in lower 2GB)
  71.     for (i = 0; i < first_kernel_page; i++) {
  72.         init_pte_level0_section(&page_table[i], i);
  73.     }
  74.  
  75.     // create 1:1 virtual-physical mapping in kernel space (upper 2GB),
  76.     // physical addresses start from 0
  77.     for (i = first_kernel_page; i < PTL0_ENTRIES; i++) {
  78.         init_pte_level0_section(&page_table[i], i - first_kernel_page);
  79.     }
  80. }
  81.  
  82.  
  83. /** Starts the MMU - initializes page table and enables paging.
  84.  */
  85. void mmu_start() {
  86.     init_page_table();
  87.     set_ptl0_address(page_table);
  88.     enable_paging();
  89. }
  90.  
  91.  
  92. /** @}
  93.  */
  94.  
  95.