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1 | jermar | 1 | /* |
2 | * Copyright (C) 2001-2004 Jakub Jermar |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | #include <arch/types.h> |
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30 | #include <config.h> |
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31 | #include <func.h> |
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32 | #include <mm/frame.h> |
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33 | #include <mm/page.h> |
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34 | #include <arch/mm/page.h> |
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35 | #include <arch/interrupt.h> |
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36 | #include <arch/asm.h> |
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37 | #include <synch/spinlock.h> |
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38 | |||
39 | /* |
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40 | * Note. |
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11 | jermar | 41 | * This is the preliminary code for controlling paging mechanism on ia32. It is |
1 | jermar | 42 | * needed by other parts of the kernel for its ability to map virtual addresses |
43 | * to physical. SMP code relies on this feature. Other than that, this code is |
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44 | * by no means meant to implement virtual memory in terms of swapping pages in |
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45 | * and out. |
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46 | */ |
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47 | |||
48 | __address bootstrap_dba; |
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49 | |||
50 | void page_arch_init(void) |
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51 | { |
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52 | __address dba; |
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53 | __u32 i; |
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54 | |||
55 | if (config.cpu_active == 1) { |
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56 | dba = frame_alloc(FRAME_KA | FRAME_PANIC); |
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57 | memsetb(dba, PAGE_SIZE, 0); |
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58 | cpu_write_dba(dba); |
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59 | |||
60 | bootstrap_dba = dba; |
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61 | |||
62 | /* |
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63 | * Identity mapping for all but 0th page. |
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64 | */ |
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65 | for (i = 1; i < frames; i++) |
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66 | map_page_to_frame(i * PAGE_SIZE, i * PAGE_SIZE, PAGE_CACHEABLE, 0); |
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67 | |||
68 | trap_register(14, page_fault); |
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69 | } |
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70 | else { |
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71 | |||
72 | /* |
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73 | * Application processors need to create their own view of the |
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74 | * virtual address space. Because of that, each AP copies |
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75 | * already-initialized paging information from the bootstrap |
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76 | * processor and adjusts it to fulfill its needs. |
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77 | */ |
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78 | |||
79 | dba = frame_alloc(FRAME_KA | FRAME_PANIC); |
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80 | memcopy(bootstrap_dba, dba, PAGE_SIZE); |
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81 | cpu_write_dba(dba); |
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82 | } |
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83 | |||
84 | paging_on(); |
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85 | } |
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86 | |||
87 | /* |
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88 | * Besides mapping pages to frames, this function also sets the present bit of |
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89 | * the page's specifier in both page directory and respective page table. If |
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90 | * the page table for this page has not been allocated so far, it will take |
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91 | * care of it and allocate the necessary frame. |
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92 | * |
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93 | * When the copy parameter is positive, map_page_to_frame will not overwrite |
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94 | * the current mapping. It will allocate a new frame and do the mapping on it |
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95 | * instead. |
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96 | * |
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97 | * PAGE_CACHEABLE flag: when set, it turns caches for that page on |
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98 | * PAGE_NOT_PRESENT flag: when set, it marks the page not present |
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99 | * PAGE_USER flag: when set, the page is accessible from userspace |
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100 | */ |
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101 | void map_page_to_frame(__address page, __address frame, int flags, int copy) |
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102 | { |
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103 | struct page_specifier *pd, *pt; |
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104 | __address dba, newpt; |
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105 | int pde, pte; |
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106 | |||
107 | dba = cpu_read_dba(); |
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108 | |||
109 | pde = page >> 22; /* page directory entry */ |
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110 | pte = (page >> 12) & 0x3ff; /* page table entry */ |
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111 | |||
112 | pd = (struct page_specifier *) dba; |
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113 | |||
114 | if (!pd[pde].present) { |
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115 | /* |
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116 | * There is currently no page table for this address. Allocate |
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117 | * frame for the page table and clean it. |
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118 | */ |
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119 | newpt = frame_alloc(FRAME_KA); |
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120 | pd[pde].frame_address = newpt >> 12; |
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121 | memsetb(newpt, PAGE_SIZE, 0); |
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122 | pd[pde].present = 1; |
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123 | pd[pde].uaccessible = 1; |
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124 | } |
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125 | if (copy) { |
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126 | newpt = frame_alloc(FRAME_KA); |
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127 | memcopy(pd[pde].frame_address << 12, newpt, PAGE_SIZE); |
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128 | pd[pde].frame_address = newpt >> 12; |
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129 | } |
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34 | jermar | 130 | |
1 | jermar | 131 | pt = (struct page_specifier *) (pd[pde].frame_address << 12); |
132 | |||
133 | pt[pte].frame_address = frame >> 12; |
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134 | pt[pte].present = !(flags & PAGE_NOT_PRESENT); |
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135 | pt[pte].page_cache_disable = !(flags & PAGE_CACHEABLE); |
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136 | pt[pte].uaccessible = (flags & PAGE_USER) != 0; |
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137 | pt[pte].writeable = (flags & PAGE_WRITE) != 0; |
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138 | } |