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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 - 2018, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Uefi.h>
#include <Library/BaseLib.h>
#include <FspEas.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
EFIAPI
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.
@param[in] Param2 The second parameter to pass to 32bit code.
@return EFI_STATUS.
**/
EFI_STATUS
Execute32BitCode (
IN UINT64 Function,
IN UINT64 Param1,
IN UINT64 Param2
)
{
EFI_STATUS Status;
IA32_DESCRIPTOR Idtr;
//
// Idtr might be changed inside of FSP. 32bit FSP only knows the <4G address.
// If IDTR.Base is >4G, FSP can not handle. So we need save/restore IDTR here for X64 only.
// Interrupt is already disabled here, so it is safety to update IDTR.
//
AsmReadIdtr (&Idtr);
Status = AsmExecute32BitCode (Function, Param1, Param2, &mGdt);
AsmWriteIdtr (&Idtr);
return Status;
}
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