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