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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;
| }
|
|
|
