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1 | /*++\r |
2 | \r |
3 | Copyright (c) 2006, Intel Corporation \r |
4 | All rights reserved. This program and the accompanying materials \r |
5 | are licensed and made available under the terms and conditions of the BSD License \r |
6 | which accompanies this distribution. The full text of the license may be found at \r |
7 | http://opensource.org/licenses/bsd-license.php \r |
8 | \r |
9 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r |
10 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r |
11 | \r |
12 | Module Name:\r |
13 | VirtualMemory.c\r |
14 | \r |
15 | Abstract:\r |
16 | \r |
17 | x64 Virtual Memory Management Services in the form of an IA-32 driver. \r |
18 | Used to establish a 1:1 Virtual to Physical Mapping that is required to\r |
19 | enter Long Mode (x64 64-bit mode).\r |
20 | \r |
21 | While we make a 1:1 mapping (identity mapping) for all physical pages \r |
22 | we still need to use the MTRR's to ensure that the cachability attirbutes\r |
23 | for all memory regions is correct.\r |
24 | \r |
25 | The basic idea is to use 2MB page table entries where ever possible. If\r |
26 | more granularity of cachability is required then 4K page tables are used.\r |
27 | \r |
28 | References:\r |
29 | 1) IA-32 Intel(R) Atchitecture Software Developer's Manual Volume 1:Basic Architecture, Intel\r |
30 | 2) IA-32 Intel(R) Atchitecture Software Developer's Manual Volume 2:Instruction Set Reference, Intel\r |
31 | 3) IA-32 Intel(R) Atchitecture Software Developer's Manual Volume 3:System Programmer's Guide, Intel\r |
32 | \r |
33 | --*/ \r |
34 | \r |
35 | #include "VirtualMemory.h"\r |
36 | \r |
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37 | EFI_PHYSICAL_ADDRESS\r |
38 | CreateIdentityMappingPageTables (\r |
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39 | VOID\r |
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40 | )\r |
41 | /*++\r |
42 | \r |
43 | Routine Description:\r |
44 | \r |
45 | Allocates and fills in the Page Directory and Page Table Entries to\r |
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46 | establish a 1:1 Virtual to Physical mapping.\r |
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47 | \r |
48 | Arguments:\r |
49 | \r |
50 | NumberOfProcessorPhysicalAddressBits - Number of processor address bits to use.\r |
51 | Limits the number of page table entries \r |
52 | to the physical address space.\r |
53 | \r |
54 | Returns:\r |
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55 | \r |
56 | EFI_SUCCESS The 1:1 Virtual to Physical identity mapping was created\r |
57 | \r |
58 | --*/\r |
59 | { \r |
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60 | UINT32 RegEax;\r |
61 | UINT8 PhysicalAddressBits;\r |
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62 | EFI_PHYSICAL_ADDRESS PageAddress;\r |
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63 | UINTN IndexOfPml4Entries;\r |
64 | UINTN IndexOfPdpEntries;\r |
65 | UINTN IndexOfPageDirectoryEntries;\r |
66 | UINTN NumberOfPml4EntriesNeeded;\r |
67 | UINTN NumberOfPdpEntriesNeeded;\r |
68 | PAGE_MAP_AND_DIRECTORY_POINTER *PageMapLevel4Entry;\r |
69 | PAGE_MAP_AND_DIRECTORY_POINTER *PageMap;\r |
70 | PAGE_MAP_AND_DIRECTORY_POINTER *PageDirectoryPointerEntry;\r |
71 | PAGE_TABLE_ENTRY *PageDirectoryEntry;\r |
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72 | \r |
73 | //\r |
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74 | // By architecture only one PageMapLevel4 exists - so lets allocate storage for it.\r |
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75 | //\r |
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76 | PageMap = AllocatePages (1);\r |
77 | ASSERT (PageMap != NULL);\r |
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78 | \r |
79 | //\r |
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80 | // Get physical address bits supported.\r |
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81 | //\r |
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82 | AsmCpuid (0x80000000, &RegEax, NULL, NULL, NULL);\r |
83 | if (RegEax >= 0x80000008) {\r |
84 | AsmCpuid (0x80000008, &RegEax, NULL, NULL, NULL);\r |
85 | PhysicalAddressBits = (UINT8) RegEax;\r |
86 | } else {\r |
87 | PhysicalAddressBits = 36;\r |
88 | }\r |
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89 | \r |
90 | //\r |
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91 | // Calculate the table entries needed.\r |
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92 | //\r |
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93 | if (PhysicalAddressBits <= 39 ) {\r |
94 | NumberOfPml4EntriesNeeded = 1;\r |
95 | NumberOfPdpEntriesNeeded = 1 << (PhysicalAddressBits - 30);\r |
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96 | } else {\r |
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97 | NumberOfPml4EntriesNeeded = 1 << (PhysicalAddressBits - 39);\r |
98 | NumberOfPdpEntriesNeeded = 512;\r |
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99 | }\r |
100 | \r |
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101 | PageMapLevel4Entry = PageMap;\r |
102 | PageAddress = 0;\r |
103 | for (IndexOfPml4Entries = 0; IndexOfPml4Entries < NumberOfPml4EntriesNeeded; IndexOfPml4Entries++, PageMapLevel4Entry++) {\r |
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104 | //\r |
105 | // Each PML4 entry points to a page of Page Directory Pointer entires.\r |
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106 | // So lets allocate space for them and fill them in in the IndexOfPdpEntries loop.\r |
107 | //\r |
108 | PageDirectoryPointerEntry = AllocatePages (1);\r |
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109 | ASSERT (PageDirectoryPointerEntry != NULL);\r |
110 | \r |
111 | //\r |
112 | // Make a PML4 Entry\r |
113 | //\r |
114 | PageMapLevel4Entry->Uint64 = (UINT64)(UINTN)PageDirectoryPointerEntry;\r |
115 | PageMapLevel4Entry->Bits.ReadWrite = 1;\r |
116 | PageMapLevel4Entry->Bits.Present = 1;\r |
117 | \r |
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118 | for (IndexOfPdpEntries = 0; IndexOfPdpEntries < NumberOfPdpEntriesNeeded; IndexOfPdpEntries++, PageDirectoryPointerEntry++) {\r |
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119 | //\r |
120 | // Each Directory Pointer entries points to a page of Page Directory entires.\r |
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121 | // So allocate space for them and fill them in in the IndexOfPageDirectoryEntries loop.\r |
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122 | // \r |
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123 | PageDirectoryEntry = AllocatePages (1);\r |
124 | ASSERT (PageDirectoryEntry != NULL);\r |
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125 | \r |
126 | //\r |
127 | // Fill in a Page Directory Pointer Entries\r |
128 | //\r |
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129 | PageDirectoryPointerEntry->Uint64 = (UINT64)(UINTN)PageDirectoryEntry;\r |
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130 | PageDirectoryPointerEntry->Bits.ReadWrite = 1;\r |
131 | PageDirectoryPointerEntry->Bits.Present = 1;\r |
132 | \r |
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133 | for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PageAddress += 0x200000) {\r |
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134 | //\r |
135 | // Fill in the Page Directory entries\r |
136 | //\r |
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137 | PageDirectoryEntry->Uint64 = (UINT64)PageAddress;\r |
138 | PageDirectoryEntry->Bits.ReadWrite = 1;\r |
139 | PageDirectoryEntry->Bits.Present = 1;\r |
140 | PageDirectoryEntry->Bits.MustBe1 = 1;\r |
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141 | \r |
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142 | }\r |
143 | }\r |
144 | }\r |
145 | \r |
146 | //\r |
147 | // For the PML4 entries we are not using fill in a null entry.\r |
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148 | // For now we just copy the first entry.\r |
149 | //\r |
150 | for (; IndexOfPml4Entries < 512; IndexOfPml4Entries++, PageMapLevel4Entry++) {\r |
151 | CopyMem (\r |
152 | PageMapLevel4Entry,\r |
153 | PageMap,\r |
154 | sizeof (PAGE_MAP_AND_DIRECTORY_POINTER)\r |
155 | );\r |
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156 | }\r |
157 | \r |
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158 | return (EFI_PHYSICAL_ADDRESS) PageMap;\r |
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159 | }\r |
160 | \r |