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| /** @file
| C based implementation of IA32 interrupt handling only
| requiring a minimal assembly interrupt entry point.
|
| Copyright (c) 2006 - 2021, Intel Corporation. All rights reserved.<BR>
| SPDX-License-Identifier: BSD-2-Clause-Patent
|
| **/
|
| #include "CpuDxe.h"
| #include "CpuGdt.h"
|
| //
| // Global descriptor table (GDT) Template
| //
| STATIC GDT_ENTRIES mGdtTemplate = {
| //
| // NULL_SEL
| //
| {
| 0x0, // limit 15:0
| 0x0, // base 15:0
| 0x0, // base 23:16
| 0x0, // type
| 0x0, // limit 19:16, flags
| 0x0, // base 31:24
| },
| //
| // LINEAR_SEL
| //
| {
| 0x0FFFF, // limit 15:0
| 0x0, // base 15:0
| 0x0, // base 23:16
| 0x092, // present, ring 0, data, read/write
| 0x0CF, // page-granular, 32-bit
| 0x0,
| },
| //
| // LINEAR_CODE_SEL
| //
| {
| 0x0FFFF, // limit 15:0
| 0x0, // base 15:0
| 0x0, // base 23:16
| 0x09F, // present, ring 0, code, execute/read, conforming, accessed
| 0x0CF, // page-granular, 32-bit
| 0x0,
| },
| //
| // SYS_DATA_SEL
| //
| {
| 0x0FFFF, // limit 15:0
| 0x0, // base 15:0
| 0x0, // base 23:16
| 0x093, // present, ring 0, data, read/write, accessed
| 0x0CF, // page-granular, 32-bit
| 0x0,
| },
| //
| // SYS_CODE_SEL
| //
| {
| 0x0FFFF, // limit 15:0
| 0x0, // base 15:0
| 0x0, // base 23:16
| 0x09A, // present, ring 0, code, execute/read
| 0x0CF, // page-granular, 32-bit
| 0x0,
| },
| //
| // SYS_CODE16_SEL
| //
| {
| 0x0FFFF, // limit 15:0
| 0x0, // base 15:0
| 0x0, // base 23:16
| 0x09A, // present, ring 0, code, execute/read
| 0x08F, // page-granular, 16-bit
| 0x0, // base 31:24
| },
| //
| // LINEAR_DATA64_SEL
| //
| {
| 0x0FFFF, // limit 15:0
| 0x0, // base 15:0
| 0x0, // base 23:16
| 0x092, // present, ring 0, data, read/write
| 0x0CF, // page-granular, 32-bit
| 0x0,
| },
| //
| // LINEAR_CODE64_SEL
| //
| {
| 0x0FFFF, // limit 15:0
| 0x0, // base 15:0
| 0x0, // base 23:16
| 0x09A, // present, ring 0, code, execute/read
| 0x0AF, // page-granular, 64-bit code
| 0x0, // base (high)
| },
| //
| // SPARE5_SEL
| //
| {
| 0x0, // limit 15:0
| 0x0, // base 15:0
| 0x0, // base 23:16
| 0x0, // type
| 0x0, // limit 19:16, flags
| 0x0, // base 31:24
| },
| };
|
| /**
| Initialize Global Descriptor Table.
|
| **/
| VOID
| InitGlobalDescriptorTable (
| VOID
| )
| {
| EFI_STATUS Status;
| GDT_ENTRIES *Gdt;
| IA32_DESCRIPTOR Gdtr;
| EFI_PHYSICAL_ADDRESS Memory;
|
| //
| // Allocate Runtime Data below 4GB for the GDT
| // AP uses the same GDT when it's waken up from real mode so
| // the GDT needs to be below 4GB.
| //
| Memory = SIZE_4GB - 1;
| Status = gBS->AllocatePages (
| AllocateMaxAddress,
| EfiRuntimeServicesData,
| EFI_SIZE_TO_PAGES (sizeof (mGdtTemplate)),
| &Memory
| );
| ASSERT_EFI_ERROR (Status);
| ASSERT ((Memory != 0) && (Memory < SIZE_4GB));
| Gdt = (GDT_ENTRIES *) (UINTN) Memory;
|
| //
| // Initialize all GDT entries
| //
| CopyMem (Gdt, &mGdtTemplate, sizeof (mGdtTemplate));
|
| //
| // Write GDT register
| //
| Gdtr.Base = (UINT32) (UINTN) Gdt;
| Gdtr.Limit = (UINT16) (sizeof (mGdtTemplate) - 1);
| AsmWriteGdtr (&Gdtr);
|
| //
| // Update selector (segment) registers base on new GDT
| //
| SetCodeSelector ((UINT16)CPU_CODE_SEL);
| SetDataSelectors ((UINT16)CPU_DATA_SEL);
| }
|
|
