EdkModulePkg/Core/DxeIplX64Peim/x64/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 EFI_PHYSICAL_ADDRESS
  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
  73   //
  74   // By architecture only one PageMapLevel4 exists - so lets allocate storage for it.
  75   //
  76   PageMap = AllocatePages (1);
  77   ASSERT (PageMap != NULL);
  78
  79   //
  80   // Get physical address bits supported.
  81   //
  82   AsmCpuid (0x80000000, &RegEax, NULL, NULL, NULL);
  83   if (RegEax >= 0x80000008) {
  84     AsmCpuid (0x80000008, &RegEax, NULL, NULL, NULL);
  85     PhysicalAddressBits = (UINT8) RegEax;
  86   } else {
  87     PhysicalAddressBits = 36;
  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   PageMapLevel4Entry = PageMap;
 102   PageAddress        = 0;
 103   for (IndexOfPml4Entries = 0; IndexOfPml4Entries < NumberOfPml4EntriesNeeded; IndexOfPml4Entries++, PageMapLevel4Entry++) {
 104     //
 105     // Each PML4 entry points to a page of Page Directory Pointer entires.
 106     // So lets allocate space for them and fill them in in the IndexOfPdpEntries loop.
 107     //
 108     PageDirectoryPointerEntry = AllocatePages (1);
 109     ASSERT (PageDirectoryPointerEntry != NULL);
 110
 111     //
 112     // Make a PML4 Entry
 113     //
 114     PageMapLevel4Entry->Uint64 = (UINT64)(UINTN)PageDirectoryPointerEntry;
 115     PageMapLevel4Entry->Bits.ReadWrite = 1;
 116     PageMapLevel4Entry->Bits.Present = 1;
 117
 118     for (IndexOfPdpEntries = 0; IndexOfPdpEntries < NumberOfPdpEntriesNeeded; IndexOfPdpEntries++, PageDirectoryPointerEntry++) {
 119       //
 120       // Each Directory Pointer entries points to a page of Page Directory entires.
 121       // So allocate space for them and fill them in in the IndexOfPageDirectoryEntries loop.
 122       //
 123       PageDirectoryEntry = AllocatePages (1);
 124       ASSERT (PageDirectoryEntry != NULL);
 125
 126       //
 127       // Fill in a Page Directory Pointer Entries
 128       //
 129       PageDirectoryPointerEntry->Uint64 = (UINT64)(UINTN)PageDirectoryEntry;
 130       PageDirectoryPointerEntry->Bits.ReadWrite = 1;
 131       PageDirectoryPointerEntry->Bits.Present = 1;
 132
 133       for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PageAddress += 0x200000) {
 134         //
 135         // Fill in the Page Directory entries
 136         //
 137         PageDirectoryEntry->Uint64 = (UINT64)PageAddress;
 138         PageDirectoryEntry->Bits.ReadWrite = 1;
 139         PageDirectoryEntry->Bits.Present = 1;
 140         PageDirectoryEntry->Bits.MustBe1 = 1;
 141
 142       }
 143     }
 144   }
 145
 146   //
 147   // For the PML4 entries we are not using fill in a null entry.
 148   // For now we just copy the first entry.
 149   //
 150   for (; IndexOfPml4Entries < 512; IndexOfPml4Entries++, PageMapLevel4Entry++) {
 151      CopyMem (
 152        PageMapLevel4Entry,
 153        PageMap,
 154        sizeof (PAGE_MAP_AND_DIRECTORY_POINTER)
 155        );
 156   }
 157
 158   return (EFI_PHYSICAL_ADDRESS) (UINTN)PageMap; // FIXME
 159 }
 160