EdkModulePkg/Core/DxeIplPeim/Ia32/VirtualMemory.c

   1 /*++
   2
   3 Copyright (c) 2006, Intel Corporation
   4 All rights reserved. This program and the accompanying materials
   5 are licensed and made available under the terms and conditions of the BSD License
   6 which accompanies this distribution.  The full text of the license may be found at
   7 http://opensource.org/licenses/bsd-license.php
   8
   9 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11
  12 Module Name:
  13   VirtualMemory.c
  14
  15 Abstract:
  16
  17   x64 Virtual Memory Management Services in the form of an IA-32 driver.
  18   Used to establish a 1:1 Virtual to Physical Mapping that is required to
  19   enter Long Mode (x64 64-bit mode).
  20
  21   While we make a 1:1 mapping (identity mapping) for all physical pages
  22   we still need to use the MTRR's to ensure that the cachability attirbutes
  23   for all memory regions is correct.
  24
  25   The basic idea is to use 2MB page table entries where ever possible. If
  26   more granularity of cachability is required then 4K page tables are used.
  27
  28   References:
  29     1) IA-32 Intel(R) Atchitecture Software Developer's Manual Volume 1:Basic Architecture, Intel
  30     2) IA-32 Intel(R) Atchitecture Software Developer's Manual Volume 2:Instruction Set Reference, Intel
  31     3) IA-32 Intel(R) Atchitecture Software Developer's Manual Volume 3:System Programmer's Guide, Intel
  32
  33 --*/
  34
  35 #include "VirtualMemory.h"
  36
  37 UINTN
  38 CreateIdentityMappingPageTables (
  39   VOID
  40   )
  41 /*++
  42
  43 Routine Description:
  44
  45   Allocates and fills in the Page Directory and Page Table Entries to
  46   establish a 1:1 Virtual to Physical mapping.
  47
  48 Arguments:
  49
  50   NumberOfProcessorPhysicalAddressBits - Number of processor address bits to use.
  51                                          Limits the number of page table entries
  52                                          to the physical address space.
  53
  54 Returns:
  55
  56   EFI_SUCCESS           The 1:1 Virtual to Physical identity mapping was created
  57
  58 --*/
  59 {
  60   UINT32                                        RegEax;
  61   UINT8                                         PhysicalAddressBits;
  62   EFI_PHYSICAL_ADDRESS                          PageAddress;
  63   UINTN                                         IndexOfPml4Entries;
  64   UINTN                                         IndexOfPdpEntries;
  65   UINTN                                         IndexOfPageDirectoryEntries;
  66   UINTN                                         NumberOfPml4EntriesNeeded;
  67   UINTN                                         NumberOfPdpEntriesNeeded;
  68   PAGE_MAP_AND_DIRECTORY_POINTER                *PageMapLevel4Entry;
  69   PAGE_MAP_AND_DIRECTORY_POINTER                *PageMap;
  70   PAGE_MAP_AND_DIRECTORY_POINTER                *PageDirectoryPointerEntry;
  71   PAGE_TABLE_ENTRY                              *PageDirectoryEntry;
  72   UINTN                                         TotalPagesNum;
  73   UINTN                                         BigPageAddress;
  74
  75   //
  76   // Get physical address bits supported.
  77   //
  78   AsmCpuid (0x80000000, &RegEax, NULL, NULL, NULL);
  79   if (RegEax >= 0x80000008) {
  80     AsmCpuid (0x80000008, &RegEax, NULL, NULL, NULL);
  81     PhysicalAddressBits = (UINT8) RegEax;
  82   } else {
  83     PhysicalAddressBits = 36;
  84   }
  85
  86   //
  87   // Calculate the table entries needed.
  88   //
  89   if (PhysicalAddressBits <= 39 ) {
  90     NumberOfPml4EntriesNeeded = 1;
  91     NumberOfPdpEntriesNeeded =  1 << (PhysicalAddressBits - 30);
  92   } else {
  93     NumberOfPml4EntriesNeeded = 1 << (PhysicalAddressBits - 39);
  94     NumberOfPdpEntriesNeeded = 512;
  95   }
  96
  97   //
  98   // Pre-allocate big pages to avoid later allocations.
  99   //
 100   TotalPagesNum = (NumberOfPdpEntriesNeeded + 1) * NumberOfPml4EntriesNeeded + 1;
 101   BigPageAddress = (UINTN) AllocatePages (TotalPagesNum);
 102   ASSERT (BigPageAddress != 0);
 103
 104   //
 105   // By architecture only one PageMapLevel4 exists - so lets allocate storage for it.
 106   //
 107   PageMap         = (VOID *) BigPageAddress;
 108   BigPageAddress += EFI_PAGE_SIZE;
 109
 110   PageMapLevel4Entry = PageMap;
 111   PageAddress        = 0;
 112   for (IndexOfPml4Entries = 0; IndexOfPml4Entries < NumberOfPml4EntriesNeeded; IndexOfPml4Entries++, PageMapLevel4Entry++) {
 113     //
 114     // Each PML4 entry points to a page of Page Directory Pointer entires.
 115     // So lets allocate space for them and fill them in in the IndexOfPdpEntries loop.
 116     //
 117     PageDirectoryPointerEntry = (VOID *) BigPageAddress;
 118     BigPageAddress += EFI_PAGE_SIZE;
 119
 120     //
 121     // Make a PML4 Entry
 122     //
 123     PageMapLevel4Entry->Uint64 = (UINT64)(UINTN)PageDirectoryPointerEntry;
 124     PageMapLevel4Entry->Bits.ReadWrite = 1;
 125     PageMapLevel4Entry->Bits.Present = 1;
 126
 127     for (IndexOfPdpEntries = 0; IndexOfPdpEntries < NumberOfPdpEntriesNeeded; IndexOfPdpEntries++, PageDirectoryPointerEntry++) {
 128       //
 129       // Each Directory Pointer entries points to a page of Page Directory entires.
 130       // So allocate space for them and fill them in in the IndexOfPageDirectoryEntries loop.
 131       //
 132       PageDirectoryEntry = (VOID *) BigPageAddress;
 133       BigPageAddress += EFI_PAGE_SIZE;
 134
 135       //
 136       // Fill in a Page Directory Pointer Entries
 137       //
 138       PageDirectoryPointerEntry->Uint64 = (UINT64)(UINTN)PageDirectoryEntry;
 139       PageDirectoryPointerEntry->Bits.ReadWrite = 1;
 140       PageDirectoryPointerEntry->Bits.Present = 1;
 141
 142       for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PageAddress += 0x200000) {
 143         //
 144         // Fill in the Page Directory entries
 145         //
 146         PageDirectoryEntry->Uint64 = (UINT64)PageAddress;
 147         PageDirectoryEntry->Bits.ReadWrite = 1;
 148         PageDirectoryEntry->Bits.Present = 1;
 149         PageDirectoryEntry->Bits.MustBe1 = 1;
 150
 151       }
 152     }
 153   }
 154
 155   //
 156   // For the PML4 entries we are not using fill in a null entry.
 157   // For now we just copy the first entry.
 158   //
 159   for (; IndexOfPml4Entries < 512; IndexOfPml4Entries++, PageMapLevel4Entry++) {
 160      CopyMem (
 161        PageMapLevel4Entry,
 162        PageMap,
 163        sizeof (PAGE_MAP_AND_DIRECTORY_POINTER)
 164        );
 165   }
 166
 167   return (UINTN)PageMap; // FIXME
 168 }
 169