mirror of https://github.com/acidanthera/audk.git
104 lines
3.0 KiB
C
104 lines
3.0 KiB
C
/** @file
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Execute 32-bit code in Long Mode.
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Provide a thunk function to transition from long mode to compatibility mode to execute 32-bit code and then transit
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back to long mode.
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Copyright (c) 2014 - 2018, 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 <Uefi.h>
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#include <Library/BaseLib.h>
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#include <FspEas.h>
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#pragma pack(1)
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typedef union {
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struct {
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UINT32 LimitLow : 16;
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UINT32 BaseLow : 16;
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UINT32 BaseMid : 8;
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UINT32 Type : 4;
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UINT32 System : 1;
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UINT32 Dpl : 2;
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UINT32 Present : 1;
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UINT32 LimitHigh : 4;
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UINT32 Software : 1;
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UINT32 Reserved : 1;
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UINT32 DefaultSize : 1;
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UINT32 Granularity : 1;
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UINT32 BaseHigh : 8;
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} Bits;
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UINT64 Uint64;
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} IA32_GDT;
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#pragma pack()
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GLOBAL_REMOVE_IF_UNREFERENCED IA32_GDT mGdtEntries[] = {
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{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}, /* 0x0: reserve */
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{{0xFFFF, 0, 0, 0xB, 1, 0, 1, 0xF, 0, 0, 1, 1, 0}}, /* 0x8: compatibility mode */
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{{0xFFFF, 0, 0, 0xB, 1, 0, 1, 0xF, 0, 1, 0, 1, 0}}, /* 0x10: for long mode */
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{{0xFFFF, 0, 0, 0x3, 1, 0, 1, 0xF, 0, 0, 1, 1, 0}}, /* 0x18: data */
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{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}, /* 0x20: reserve */
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};
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//
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// IA32 Gdt register
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//
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GLOBAL_REMOVE_IF_UNREFERENCED IA32_DESCRIPTOR mGdt = {
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sizeof (mGdtEntries) - 1,
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(UINTN) mGdtEntries
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};
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/**
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Assembly function to transition from long mode to compatibility mode to execute 32-bit code and then transit back to
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long mode.
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@param[in] Function The 32bit code entry to be executed.
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@param[in] Param1 The first parameter to pass to 32bit code
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@param[in] Param2 The second parameter to pass to 32bit code
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@param[in] InternalGdtr The GDT and GDT descriptor used by this library
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@return status.
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**/
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UINT32
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EFIAPI
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AsmExecute32BitCode (
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IN UINT64 Function,
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IN UINT64 Param1,
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IN UINT64 Param2,
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IN IA32_DESCRIPTOR *InternalGdtr
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);
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/**
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Wrapper for a thunk to transition from long mode to compatibility mode to execute 32-bit code and then transit back to
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long mode.
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@param[in] Function The 32bit code entry to be executed.
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@param[in] Param1 The first parameter to pass to 32bit code.
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@param[in] Param2 The second parameter to pass to 32bit code.
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@return EFI_STATUS.
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**/
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EFI_STATUS
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Execute32BitCode (
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IN UINT64 Function,
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IN UINT64 Param1,
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IN UINT64 Param2
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)
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{
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EFI_STATUS Status;
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IA32_DESCRIPTOR Idtr;
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//
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// Idtr might be changed inside of FSP. 32bit FSP only knows the <4G address.
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// If IDTR.Base is >4G, FSP can not handle. So we need save/restore IDTR here for X64 only.
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// Interrupt is already disabled here, so it is safety to update IDTR.
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//
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AsmReadIdtr (&Idtr);
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Status = AsmExecute32BitCode (Function, Param1, Param2, &mGdt);
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AsmWriteIdtr (&Idtr);
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return Status;
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}
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