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   UINT8                                         PhysicalAddressBits;
  61   EFI_PHYSICAL_ADDRESS                          PageAddress;
  62   UINTN                                         IndexOfPml4Entries;
  63   UINTN                                         IndexOfPdpEntries;
  64   UINTN                                         IndexOfPageDirectoryEntries;
  65   UINTN                                         NumberOfPml4EntriesNeeded;
  66   UINTN                                         NumberOfPdpEntriesNeeded;
  67   PAGE_MAP_AND_DIRECTORY_POINTER                *PageMapLevel4Entry;
  68   PAGE_MAP_AND_DIRECTORY_POINTER                *PageMap;
  69   PAGE_MAP_AND_DIRECTORY_POINTER                *PageDirectoryPointerEntry;
  70   PAGE_TABLE_ENTRY                              *PageDirectoryEntry;
  71   UINTN                                         TotalPagesNum;
  72   UINTN                                         BigPageAddress;
  73   VOID                                          *Hob;
  74
  75   //
  76   // Get physical address bits supported from CPU HOB.
  77   //
  78   PhysicalAddressBits = 36;
  79
  80   Hob = GetFirstHob (EFI_HOB_TYPE_CPU);
  81   if (Hob != NULL) {
  82     PhysicalAddressBits = ((EFI_HOB_CPU *) Hob)->SizeOfMemorySpace;
  83   }
  84
  85   //
  86   // Calculate the table entries needed.
  87   //
  88   if (PhysicalAddressBits <= 39 ) {
  89     NumberOfPml4EntriesNeeded = 1;
  90     NumberOfPdpEntriesNeeded =  1 << (PhysicalAddressBits - 30);
  91   } else {
  92     NumberOfPml4EntriesNeeded = 1 << (PhysicalAddressBits - 39);
  93     NumberOfPdpEntriesNeeded = 512;
  94   }
  95
  96   //
  97   // Pre-allocate big pages to avoid later allocations.
  98   //
  99   TotalPagesNum = (NumberOfPdpEntriesNeeded + 1) * NumberOfPml4EntriesNeeded + 1;
 100   BigPageAddress = (UINTN) AllocatePages (TotalPagesNum);
 101   ASSERT (BigPageAddress != 0);
 102
 103   //
 104   // By architecture only one PageMapLevel4 exists - so lets allocate storage for it.
 105   //
 106   PageMap         = (VOID *) BigPageAddress;
 107   BigPageAddress += EFI_PAGE_SIZE;
 108
 109   PageMapLevel4Entry = PageMap;
 110   PageAddress        = 0;
 111   for (IndexOfPml4Entries = 0; IndexOfPml4Entries < NumberOfPml4EntriesNeeded; IndexOfPml4Entries++, PageMapLevel4Entry++) {
 112     //
 113     // Each PML4 entry points to a page of Page Directory Pointer entires.
 114     // So lets allocate space for them and fill them in in the IndexOfPdpEntries loop.
 115     //
 116     PageDirectoryPointerEntry = (VOID *) BigPageAddress;
 117     BigPageAddress += EFI_PAGE_SIZE;
 118
 119     //
 120     // Make a PML4 Entry
 121     //
 122     PageMapLevel4Entry->Uint64 = (UINT64)(UINTN)PageDirectoryPointerEntry;
 123     PageMapLevel4Entry->Bits.ReadWrite = 1;
 124     PageMapLevel4Entry->Bits.Present = 1;
 125
 126     for (IndexOfPdpEntries = 0; IndexOfPdpEntries < NumberOfPdpEntriesNeeded; IndexOfPdpEntries++, PageDirectoryPointerEntry++) {
 127       //
 128       // Each Directory Pointer entries points to a page of Page Directory entires.
 129       // So allocate space for them and fill them in in the IndexOfPageDirectoryEntries loop.
 130       //
 131       PageDirectoryEntry = (VOID *) BigPageAddress;
 132       BigPageAddress += EFI_PAGE_SIZE;
 133
 134       //
 135       // Fill in a Page Directory Pointer Entries
 136       //
 137       PageDirectoryPointerEntry->Uint64 = (UINT64)(UINTN)PageDirectoryEntry;
 138       PageDirectoryPointerEntry->Bits.ReadWrite = 1;
 139       PageDirectoryPointerEntry->Bits.Present = 1;
 140
 141       for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PageAddress += 0x200000) {
 142         //
 143         // Fill in the Page Directory entries
 144         //
 145         PageDirectoryEntry->Uint64 = (UINT64)PageAddress;
 146         PageDirectoryEntry->Bits.ReadWrite = 1;
 147         PageDirectoryEntry->Bits.Present = 1;
 148         PageDirectoryEntry->Bits.MustBe1 = 1;
 149
 150       }
 151     }
 152   }
 153
 154   //
 155   // For the PML4 entries we are not using fill in a null entry.
 156   // For now we just copy the first entry.
 157   //
 158   for (; IndexOfPml4Entries < 512; IndexOfPml4Entries++, PageMapLevel4Entry++) {
 159      CopyMem (
 160        PageMapLevel4Entry,
 161        PageMap,
 162        sizeof (PAGE_MAP_AND_DIRECTORY_POINTER)
 163        );
 164   }
 165
 166   return (UINTN)PageMap; // FIXME
 167 }
 168