UefiCpuPkg/CpuDxe/CpuGdt.c

   1 /** @file
   2   C based implemention of IA32 interrupt handling only
   3   requiring a minimal assembly interrupt entry point.
   4
   5   Copyright (c) 2006 - 2009, Intel Corporation
   6   All rights reserved. This program and the accompanying materials
   7   are licensed and made available under the terms and conditions of the BSD License
   8   which accompanies this distribution.  The full text of the license may be found at
   9   http://opensource.org/licenses/bsd-license.php
  10
  11   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13
  14 **/
  15
  16 #include "CpuDxe.h"
  17
  18
  19 //
  20 // Local structure definitions
  21 //
  22
  23 #pragma pack (1)
  24
  25 //
  26 // Global Descriptor Entry structures
  27 //
  28
  29 typedef
  30 struct _GDT_ENTRY {
  31   UINT16 limit15_0;
  32   UINT16 base15_0;
  33   UINT8  base23_16;
  34   UINT8  type;
  35   UINT8  limit19_16_and_flags;
  36   UINT8  base31_24;
  37 } GDT_ENTRY;
  38
  39 typedef
  40 struct _GDT_ENTRIES {
  41   GDT_ENTRY Null;
  42   GDT_ENTRY Linear;
  43   GDT_ENTRY LinearCode;
  44   GDT_ENTRY SysData;
  45   GDT_ENTRY SysCode;
  46   GDT_ENTRY LinearCode64;
  47   GDT_ENTRY Spare4;
  48   GDT_ENTRY Spare5;
  49 } GDT_ENTRIES;
  50
  51 #define NULL_SEL          OFFSET_OF (GDT_ENTRIES, Null)
  52 #define LINEAR_SEL        OFFSET_OF (GDT_ENTRIES, Linear)
  53 #define LINEAR_CODE_SEL   OFFSET_OF (GDT_ENTRIES, LinearCode)
  54 #define SYS_DATA_SEL      OFFSET_OF (GDT_ENTRIES, SysData)
  55 #define SYS_CODE_SEL      OFFSET_OF (GDT_ENTRIES, SysCode)
  56 #define LINEAR_CODE64_SEL OFFSET_OF (GDT_ENTRIES, LinearCode64)
  57 #define SPARE4_SEL        OFFSET_OF (GDT_ENTRIES, Spare4)
  58 #define SPARE5_SEL        OFFSET_OF (GDT_ENTRIES, Spare5)
  59
  60 #if defined (MDE_CPU_IA32)
  61 #define CPU_CODE_SEL LINEAR_CODE_SEL
  62 #define CPU_DATA_SEL LINEAR_SEL
  63 #elif defined (MDE_CPU_X64)
  64 #define CPU_CODE_SEL LINEAR_CODE64_SEL
  65 #define CPU_DATA_SEL LINEAR_SEL
  66 #else
  67 #error CPU type not supported for CPU GDT initialization!
  68 #endif
  69
  70 //
  71 // Global descriptor table (GDT) Template
  72 //
  73 STATIC GDT_ENTRIES GdtTemplate = {
  74   //
  75   // NULL_SEL
  76   //
  77   {
  78     0x0,            // limit 15:0
  79     0x0,            // base 15:0
  80     0x0,            // base 23:16
  81     0x0,            // type
  82     0x0,            // limit 19:16, flags
  83     0x0,            // base 31:24
  84   },
  85   //
  86   // LINEAR_SEL
  87   //
  88   {
  89     0x0FFFF,        // limit 0xFFFFF
  90     0x0,            // base 0
  91     0x0,
  92     0x092,          // present, ring 0, data, expand-up, writable
  93     0x0CF,          // page-granular, 32-bit
  94     0x0,
  95   },
  96   //
  97   // LINEAR_CODE_SEL
  98   //
  99   {
 100     0x0FFFF,        // limit 0xFFFFF
 101     0x0,            // base 0
 102     0x0,
 103     0x09A,          // present, ring 0, data, expand-up, writable
 104     0x0CF,          // page-granular, 32-bit
 105     0x0,
 106   },
 107   //
 108   // SYS_DATA_SEL
 109   //
 110   {
 111     0x0FFFF,        // limit 0xFFFFF
 112     0x0,            // base 0
 113     0x0,
 114     0x092,          // present, ring 0, data, expand-up, writable
 115     0x0CF,          // page-granular, 32-bit
 116     0x0,
 117   },
 118   //
 119   // SYS_CODE_SEL
 120   //
 121   {
 122     0x0FFFF,        // limit 0xFFFFF
 123     0x0,            // base 0
 124     0x0,
 125     0x09A,          // present, ring 0, data, expand-up, writable
 126     0x0CF,          // page-granular, 32-bit
 127     0x0,
 128   },
 129   //
 130   // LINEAR_CODE64_SEL
 131   //
 132   {
 133     0x0FFFF,        // limit 0xFFFFF
 134     0x0,            // base 0
 135     0x0,
 136     0x09B,          // present, ring 0, code, expand-up, writable
 137     0x0AF,          // LimitHigh (CS.L=1, CS.D=0)
 138     0x0,            // base (high)
 139   },
 140   //
 141   // SPARE4_SEL
 142   //
 143   {
 144     0x0,            // limit 0
 145     0x0,            // base 0
 146     0x0,
 147     0x0,            // present, ring 0, data, expand-up, writable
 148     0x0,            // page-granular, 32-bit
 149     0x0,
 150   },
 151   //
 152   // SPARE5_SEL
 153   //
 154   {
 155     0x0,            // limit 0
 156     0x0,            // base 0
 157     0x0,
 158     0x0,            // present, ring 0, data, expand-up, writable
 159     0x0,            // page-granular, 32-bit
 160     0x0,
 161   },
 162 };
 163
 164 /**
 165   Initialize Global Descriptor Table
 166
 167 **/
 168 VOID
 169 InitGlobalDescriptorTable (
 170   )
 171 {
 172   GDT_ENTRIES *gdt;
 173   IA32_DESCRIPTOR gdtPtr;
 174
 175   //
 176   // Allocate Runtime Data for the GDT
 177   //
 178   gdt = AllocateRuntimePool (sizeof (GdtTemplate) + 8);
 179   ASSERT (gdt != NULL);
 180   gdt = ALIGN_POINTER (gdt, 8);
 181
 182   //
 183   // Initialize all GDT entries
 184   //
 185   CopyMem (gdt, &GdtTemplate, sizeof (GdtTemplate));
 186
 187   //
 188   // Write GDT register
 189   //
 190   gdtPtr.Base = (UINT32)(UINTN)(VOID*) gdt;
 191   gdtPtr.Limit = sizeof (GdtTemplate) - 1;
 192   AsmWriteGdtr (&gdtPtr);
 193
 194   //
 195   // Update selector (segment) registers base on new GDT
 196   //
 197   SetCodeSelector ((UINT16)CPU_CODE_SEL);
 198   SetDataSelectors ((UINT16)CPU_DATA_SEL);
 199 }
 200