IntelFspWrapperPkg/Library/BaseFspApiLib/X64/DispatchExecute.c

   1 /** @file
   2   Execute 32-bit code in Long Mode.
   3   Provide a thunk function to transition from long mode to compatibility mode to execute 32-bit code and then transit
   4   back to long mode.
   5
   6   Copyright (c) 2014, Intel Corporation. All rights reserved.<BR>
   7   This program and the accompanying materials
   8   are licensed and made available under the terms and conditions of the BSD License
   9   which accompanies this distribution.  The full text of the license may be found at
  10   http://opensource.org/licenses/bsd-license.php.
  11
  12   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  13   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  14
  15 **/
  16
  17 #include <Uefi.h>
  18 #include <Library/BaseLib.h>
  19 #include <FspApi.h>
  20
  21 #pragma pack(1)
  22 typedef union {
  23   struct {
  24     UINT32  LimitLow    : 16;
  25     UINT32  BaseLow     : 16;
  26     UINT32  BaseMid     : 8;
  27     UINT32  Type        : 4;
  28     UINT32  System      : 1;
  29     UINT32  Dpl         : 2;
  30     UINT32  Present     : 1;
  31     UINT32  LimitHigh   : 4;
  32     UINT32  Software    : 1;
  33     UINT32  Reserved    : 1;
  34     UINT32  DefaultSize : 1;
  35     UINT32  Granularity : 1;
  36     UINT32  BaseHigh    : 8;
  37   } Bits;
  38   UINT64  Uint64;
  39 } IA32_GDT;
  40 #pragma pack()
  41
  42 GLOBAL_REMOVE_IF_UNREFERENCED IA32_GDT mGdtEntries[] = {
  43   {{0,      0,  0,  0,    0,  0,  0,  0,    0,  0, 0,  0,  0}}, /* 0x0:  reserve */
  44   {{0xFFFF, 0,  0,  0xB,  1,  0,  1,  0xF,  0,  0, 1,  1,  0}}, /* 0x8:  compatibility mode */
  45   {{0xFFFF, 0,  0,  0xB,  1,  0,  1,  0xF,  0,  1, 0,  1,  0}}, /* 0x10: for long mode */
  46   {{0xFFFF, 0,  0,  0x3,  1,  0,  1,  0xF,  0,  0, 1,  1,  0}}, /* 0x18: data */
  47   {{0,      0,  0,  0,    0,  0,  0,  0,    0,  0, 0,  0,  0}}, /* 0x20: reserve */
  48 };
  49
  50 //
  51 // IA32 Gdt register
  52 //
  53 GLOBAL_REMOVE_IF_UNREFERENCED IA32_DESCRIPTOR mGdt = {
  54   sizeof (mGdtEntries) - 1,
  55   (UINTN) mGdtEntries
  56   };
  57
  58 /**
  59   Assembly function to transition from long mode to compatibility mode to execute 32-bit code and then transit back to
  60   long mode.
  61
  62   @param[in] Function     The 32bit code entry to be executed.
  63   @param[in] Param1       The first parameter to pass to 32bit code
  64   @param[in] Param2       The second parameter to pass to 32bit code
  65   @param[in] InternalGdtr The GDT and GDT descriptor used by this library
  66
  67   @return status.
  68 **/
  69 UINT32
  70 AsmExecute32BitCode (
  71   IN UINT64           Function,
  72   IN UINT64           Param1,
  73   IN UINT64           Param2,
  74   IN IA32_DESCRIPTOR  *InternalGdtr
  75   );
  76
  77 /**
  78   Wrapper for a thunk  to transition from long mode to compatibility mode to execute 32-bit code and then transit back to
  79   long mode.
  80
  81   @param[in] Function     The 32bit code entry to be executed.
  82   @param[in] Param1       The first parameter to pass to 32bit code.
  83
  84   @return FSP_STATUS.
  85 **/
  86 FSP_STATUS
  87 Execute32BitCode (
  88   IN UINT64      Function,
  89   IN UINT64      Param1
  90   )
  91 {
  92   return AsmExecute32BitCode (Function, Param1, 0, &mGdt);
  93 }
  94