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 - 2015, 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 EFI_STATUS. 85 **/ 86 EFI_STATUS 87 Execute32BitCode ( 88 IN UINT64 Function, 89 IN UINT64 Param1 90 ) 91 { 92 EFI_STATUS Status; 93 IA32_DESCRIPTOR Idtr; 94 95 // 96 // Idtr might be changed inside of FSP. 32bit FSP only knows the <4G address. 97 // If IDTR.Base is >4G, FSP can not handle. So we need save/restore IDTR here for X64 only. 98 // Interrupt is already disabled here, so it is safety to update IDTR. 99 // 100 AsmReadIdtr (&Idtr); 101 Status = AsmExecute32BitCode (Function, Param1, 0, &mGdt); 102 AsmWriteIdtr (&Idtr); 103 104 return Status; 105 } 106 107
