mirror of https://github.com/acidanthera/audk.git
182 lines
3.5 KiB
C
182 lines
3.5 KiB
C
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/** @file
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Initialize GDT for Linux.
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Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#include "LoadLinuxLib.h"
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//
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// Local structure definitions
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//
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#pragma pack (1)
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//
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// Global Descriptor Entry structures
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//
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typedef struct _GDT_ENTRY {
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UINT16 Limit15_0;
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UINT16 Base15_0;
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UINT8 Base23_16;
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UINT8 Type;
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UINT8 Limit19_16_and_flags;
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UINT8 Base31_24;
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} GDT_ENTRY;
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typedef
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struct _GDT_ENTRIES {
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GDT_ENTRY Null;
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GDT_ENTRY Null2;
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GDT_ENTRY Linear;
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GDT_ENTRY LinearCode;
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GDT_ENTRY TaskSegment;
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GDT_ENTRY Spare4;
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GDT_ENTRY Spare5;
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} GDT_ENTRIES;
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#pragma pack ()
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STATIC GDT_ENTRIES *mGdt = NULL;
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//
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// Global descriptor table (GDT) Template
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//
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STATIC GDT_ENTRIES GdtTemplate = {
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//
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// Null
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//
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{
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0x0, // limit 15:0
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0x0, // base 15:0
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0x0, // base 23:16
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0x0, // type
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0x0, // limit 19:16, flags
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0x0, // base 31:24
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},
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//
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// Null2
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//
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{
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0x0, // limit 15:0
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0x0, // base 15:0
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0x0, // base 23:16
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0x0, // type
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0x0, // limit 19:16, flags
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0x0, // base 31:24
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},
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//
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// Linear
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//
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{
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0x0FFFF, // limit 0xFFFFF
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0x0, // base 0
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0x0,
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0x09A, // present, ring 0, data, expand-up, writable
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0x0CF, // page-granular, 32-bit
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0x0,
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},
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//
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// LinearCode
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//
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{
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0x0FFFF, // limit 0xFFFFF
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0x0, // base 0
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0x0,
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0x092, // present, ring 0, data, expand-up, writable
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0x0CF, // page-granular, 32-bit
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0x0,
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},
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//
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// TaskSegment
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//
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{
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0x0, // limit 0
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0x0, // base 0
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0x0,
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0x089, // ?
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0x080, // ?
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0x0,
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},
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//
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// Spare4
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//
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{
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0x0, // limit 0
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0x0, // base 0
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0x0,
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0x0, // present, ring 0, data, expand-up, writable
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0x0, // page-granular, 32-bit
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0x0,
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},
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//
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// Spare5
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//
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{
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0x0, // limit 0
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0x0, // base 0
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0x0,
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0x0, // present, ring 0, data, expand-up, writable
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0x0, // page-granular, 32-bit
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0x0,
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},
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};
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/**
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Initialize Global Descriptor Table.
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**/
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VOID
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InitLinuxDescriptorTables (
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VOID
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)
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{
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//
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// Allocate Runtime Data for the GDT
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//
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mGdt = AllocateRuntimePool (sizeof (GdtTemplate) + 8);
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ASSERT (mGdt != NULL);
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mGdt = ALIGN_POINTER (mGdt, 8);
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//
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// Initialize all GDT entries
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//
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CopyMem (mGdt, &GdtTemplate, sizeof (GdtTemplate));
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}
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/**
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Initialize Global Descriptor Table.
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**/
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VOID
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SetLinuxDescriptorTables (
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VOID
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)
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{
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IA32_DESCRIPTOR GdtPtr;
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IA32_DESCRIPTOR IdtPtr;
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//
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// Write GDT register
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//
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GdtPtr.Base = (UINT32)(UINTN)(VOID*) mGdt;
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GdtPtr.Limit = (UINT16) (sizeof (GdtTemplate) - 1);
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AsmWriteGdtr (&GdtPtr);
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IdtPtr.Base = (UINT32) 0;
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IdtPtr.Limit = (UINT16) 0;
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AsmWriteIdtr (&IdtPtr);
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}
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