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/** @file
Execute 32-bit code in Long Mode
Provide a thunk function to transition from long mode to compatibility mode to execute 32-bit code and then transit
back to long mode.
Copyright (c) 2010 - 2012, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include "ScriptSave.h"
#pragma pack(1)
typedef union {
struct {
UINT32 LimitLow : 16;
UINT32 BaseLow : 16;
UINT32 BaseMid : 8;
UINT32 Type : 4;
UINT32 System : 1;
UINT32 Dpl : 2;
UINT32 Present : 1;
UINT32 LimitHigh : 4;
UINT32 Software : 1;
UINT32 Reserved : 1;
UINT32 DefaultSize : 1;
UINT32 Granularity : 1;
UINT32 BaseHigh : 8;
} Bits;
UINT64 Uint64;
} IA32_GDT;
///
/// Byte packed structure for an IA-32 Interrupt Gate Descriptor.
///
typedef union {
struct {
UINT32 OffsetLow:16; ///< Offset bits 15..0.
UINT32 Selector:16; ///< Selector.
UINT32 Reserved_0:8; ///< Reserved.
UINT32 GateType:8; ///< Gate Type. See #defines above.
UINT32 OffsetHigh:16; ///< Offset bits 31..16.
} Bits;
UINT64 Uint64;
} IA32_IDT_ENTRY;
#pragma pack()
#define COMPATIBILITY_MODE_SELECTOR 8
//
// Global Descriptor Table (GDT)
//
GLOBAL_REMOVE_IF_UNREFERENCED IA32_GDT mGdtEntries[] = {
{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}, /* 0x0: reserve */
{{0xFFFF, 0, 0, 0xB, 1, 0, 1, 0xF, 0, 0, 1, 1, 0}}, /* 0x8: compatibility mode */
{{0xFFFF, 0, 0, 0xB, 1, 0, 1, 0xF, 0, 1, 0, 1, 0}}, /* 0x10: for long mode */
{{0xFFFF, 0, 0, 0x3, 1, 0, 1, 0xF, 0, 0, 1, 1, 0}}, /* 0x18: data */
{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}, /* 0x20: reserve */
};
//
// IA32 Gdt register
//
GLOBAL_REMOVE_IF_UNREFERENCED IA32_DESCRIPTOR mGdt = {
sizeof (mGdtEntries) - 1,
(UINTN) mGdtEntries
};
/**
Assembly function to transition from long mode to compatibility mode to execute 32-bit code and then transit back to
long mode.
@param Function The 32bit code entry to be executed.
@param Param1 The first parameter to pass to 32bit code
@param Param2 The second parameter to pass to 32bit code
@param InternalGdtr The GDT and GDT descriptor used by this library
@retval EFI_SUCCESS Execute 32bit code successfully.
@retval other Something wrong when execute the 32bit code
**/
EFI_STATUS
AsmExecute32BitCode (
IN UINT64 Function,
IN UINT64 Param1,
IN UINT64 Param2,
IN IA32_DESCRIPTOR *InternalGdtr
);
/**
Wrapper for a thunk to transition from long mode to compatibility mode to execute 32-bit code and then transit back to
long mode.
@param Function The 32bit code entry to be executed.
@param Param1 The first parameter to pass to 32bit code
@param Param2 The second parameter to pass to 32bit code
@retval EFI_SUCCESS Execute 32bit code successfully.
@retval other Something wrong when execute the 32bit code
**/
EFI_STATUS
Execute32BitCode (
IN UINT64 Function,
IN UINT64 Param1,
IN UINT64 Param2
)
{
EFI_STATUS Status;
IA32_DESCRIPTOR *Ia32Idtr;
IA32_DESCRIPTOR X64Idtr;
UINTN Ia32IdtEntryCount;
UINTN Index;
IA32_IDT_ENTRY *Ia32IdtEntry;
//
// Save x64 IDT Descriptor
//
AsmReadIdtr ((IA32_DESCRIPTOR *) &X64Idtr);
//
// Get the IA32 IDT Descriptor saved in 16 bytes in front of X64 IDT table.
//
Ia32Idtr = (IA32_DESCRIPTOR *) (UINTN) (X64Idtr.Base - 16);
Ia32IdtEntryCount = (Ia32Idtr->Limit + 1) / sizeof (IA32_IDT_ENTRY);
Ia32IdtEntry = (IA32_IDT_ENTRY *)(Ia32Idtr->Base);
for (Index = 0; Index < Ia32IdtEntryCount; Index ++ ) {
//
// Use the new Code Selector value
//
Ia32IdtEntry[Index].Bits.Selector = COMPATIBILITY_MODE_SELECTOR;
}
//
// Setup IA32 IDT table for 32-bit framework Boot Script code
//
AsmWriteIdtr (Ia32Idtr);
ASSERT (Function != 0);
Status = AsmExecute32BitCode (
Function,
Param1,
Param2,
&mGdt
);
//
// Restore X64 IDT table
//
AsmWriteIdtr ((IA32_DESCRIPTOR *) &X64Idtr);
return Status;
}
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