AsmExecute32BitCode is assembly code and needs EFIAPI Cc: Jiewen Yao <Jiewen.yao@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Chasel Chiu <chasel.chiu@intel.com> Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>
		
			
				
	
	
		
			110 lines
		
	
	
		
			3.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			110 lines
		
	
	
		
			3.4 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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  This program and the accompanying materials
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  are licensed and made available under the terms and conditions of the BSD License
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  which accompanies this distribution.  The full text of the license may be found at
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  http://opensource.org/licenses/bsd-license.php.
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  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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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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