MdeModulePkg/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 //
  36 // Include common header file for this module.
  37 //
  38 #include "CommonHeader.h"
  39
  40 #include "VirtualMemory.h"
  41
  42 UINTN
  43 CreateIdentityMappingPageTables (
  44   VOID
  45   )
  46 /*++
  47
  48 Routine Description:
  49
  50   Allocates and fills in the Page Directory and Page Table Entries to
  51   establish a 1:1 Virtual to Physical mapping.
  52
  53 Arguments:
  54
  55   NumberOfProcessorPhysicalAddressBits - Number of processor address bits to use.
  56                                          Limits the number of page table entries
  57                                          to the physical address space.
  58
  59 Returns:
  60
  61   EFI_SUCCESS           The 1:1 Virtual to Physical identity mapping was created
  62
  63 --*/
  64 {
  65   UINT8                                         PhysicalAddressBits;
  66   EFI_PHYSICAL_ADDRESS                          PageAddress;
  67   UINTN                                         IndexOfPml4Entries;
  68   UINTN                                         IndexOfPdpEntries;
  69   UINTN                                         IndexOfPageDirectoryEntries;
  70   UINTN                                         NumberOfPml4EntriesNeeded;
  71   UINTN                                         NumberOfPdpEntriesNeeded;
  72   PAGE_MAP_AND_DIRECTORY_POINTER                *PageMapLevel4Entry;
  73   PAGE_MAP_AND_DIRECTORY_POINTER                *PageMap;
  74   PAGE_MAP_AND_DIRECTORY_POINTER                *PageDirectoryPointerEntry;
  75   PAGE_TABLE_ENTRY                              *PageDirectoryEntry;
  76   UINTN                                         TotalPagesNum;
  77   UINTN                                         BigPageAddress;
  78   VOID                                          *Hob;
  79
  80   //
  81   // Get physical address bits supported from CPU HOB.
  82   //
  83   PhysicalAddressBits = 36;
  84
  85   Hob = GetFirstHob (EFI_HOB_TYPE_CPU);
  86   if (Hob != NULL) {
  87     PhysicalAddressBits = ((EFI_HOB_CPU *) Hob)->SizeOfMemorySpace;
  88   }
  89
  90   //
  91   // Calculate the table entries needed.
  92   //
  93   if (PhysicalAddressBits <= 39 ) {
  94     NumberOfPml4EntriesNeeded = 1;
  95     NumberOfPdpEntriesNeeded =  1 << (PhysicalAddressBits - 30);
  96   } else {
  97     NumberOfPml4EntriesNeeded = 1 << (PhysicalAddressBits - 39);
  98     NumberOfPdpEntriesNeeded = 512;
  99   }
 100
 101   //
 102   // Pre-allocate big pages to avoid later allocations.
 103   //
 104   TotalPagesNum = (NumberOfPdpEntriesNeeded + 1) * NumberOfPml4EntriesNeeded + 1;
 105   BigPageAddress = (UINTN) AllocatePages (TotalPagesNum);
 106   ASSERT (BigPageAddress != 0);
 107
 108   //
 109   // By architecture only one PageMapLevel4 exists - so lets allocate storage for it.
 110   //
 111   PageMap         = (VOID *) BigPageAddress;
 112   BigPageAddress += EFI_PAGE_SIZE;
 113
 114   PageMapLevel4Entry = PageMap;
 115   PageAddress        = 0;
 116   for (IndexOfPml4Entries = 0; IndexOfPml4Entries < NumberOfPml4EntriesNeeded; IndexOfPml4Entries++, PageMapLevel4Entry++) {
 117     //
 118     // Each PML4 entry points to a page of Page Directory Pointer entires.
 119     // So lets allocate space for them and fill them in in the IndexOfPdpEntries loop.
 120     //
 121     PageDirectoryPointerEntry = (VOID *) BigPageAddress;
 122     BigPageAddress += EFI_PAGE_SIZE;
 123
 124     //
 125     // Make a PML4 Entry
 126     //
 127     PageMapLevel4Entry->Uint64 = (UINT64)(UINTN)PageDirectoryPointerEntry;
 128     PageMapLevel4Entry->Bits.ReadWrite = 1;
 129     PageMapLevel4Entry->Bits.Present = 1;
 130
 131     for (IndexOfPdpEntries = 0; IndexOfPdpEntries < NumberOfPdpEntriesNeeded; IndexOfPdpEntries++, PageDirectoryPointerEntry++) {
 132       //
 133       // Each Directory Pointer entries points to a page of Page Directory entires.
 134       // So allocate space for them and fill them in in the IndexOfPageDirectoryEntries loop.
 135       //
 136       PageDirectoryEntry = (VOID *) BigPageAddress;
 137       BigPageAddress += EFI_PAGE_SIZE;
 138
 139       //
 140       // Fill in a Page Directory Pointer Entries
 141       //
 142       PageDirectoryPointerEntry->Uint64 = (UINT64)(UINTN)PageDirectoryEntry;
 143       PageDirectoryPointerEntry->Bits.ReadWrite = 1;
 144       PageDirectoryPointerEntry->Bits.Present = 1;
 145
 146       for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PageAddress += 0x200000) {
 147         //
 148         // Fill in the Page Directory entries
 149         //
 150         PageDirectoryEntry->Uint64 = (UINT64)PageAddress;
 151         PageDirectoryEntry->Bits.ReadWrite = 1;
 152         PageDirectoryEntry->Bits.Present = 1;
 153         PageDirectoryEntry->Bits.MustBe1 = 1;
 154
 155       }
 156     }
 157   }
 158
 159   //
 160   // For the PML4 entries we are not using fill in a null entry.
 161   // For now we just copy the first entry.
 162   //
 163   for (; IndexOfPml4Entries < 512; IndexOfPml4Entries++, PageMapLevel4Entry++) {
 164      CopyMem (
 165        PageMapLevel4Entry,
 166        PageMap,
 167        sizeof (PAGE_MAP_AND_DIRECTORY_POINTER)
 168        );
 169   }
 170
 171   return (UINTN)PageMap; // FIXME
 172 }
 173