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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) 2014 - 2015, 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 <Uefi.h>
#include <Library/BaseLib.h>
#include <FspApi.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;
#pragma pack()
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[in] Function The 32bit code entry to be executed.
@param[in] Param1 The first parameter to pass to 32bit code
@param[in] Param2 The second parameter to pass to 32bit code
@param[in] InternalGdtr The GDT and GDT descriptor used by this library
@return status.
**/
UINT32
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[in] Function The 32bit code entry to be executed.
@param[in] Param1 The first parameter to pass to 32bit code.
@return EFI_STATUS.
**/
EFI_STATUS
Execute32BitCode (
IN UINT64 Function,
IN UINT64 Param1
)
{
return AsmExecute32BitCode (Function, Param1, 0, &mGdt);
}
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