[mirror_edk2.git] / EdkCompatibilityPkg / Foundation / Library / Thunk16 / X86Thunk.c

/*++\r
\r
Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>\r
This program and the accompanying materials                          \r
are licensed and made available under the terms and conditions of the BSD License         \r
which accompanies this distribution.  The full text of the license may be found at        \r
http://opensource.org/licenses/bsd-license.php                                            \r
                                                                                          \r
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     \r
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             \r
\r
\r
Module Name:\r
\r
  x86Thunk.c\r
\r
Abstract:\r
\r
  Real Mode Thunk Functions\r
\r
--*/\r
\r
#include "Thunk16Lib.h"\r
#include "EfiCommonLib.h"\r
\r
extern CONST UINTN                  mCode16Size;\r
\r
extern\r
IA32_REGISTER_SET *\r
EFIAPI\r
_Thunk16 (\r
  IN OUT  IA32_REGISTER_SET         *RegisterSet,\r
  IN      UINT32                    ThunkFlags,\r
  IN      UINT32                    RealModeCs\r
  );\r
\r
extern\r
VOID\r
EFIAPI\r
_Code16Addr (\r
  VOID\r
  );\r
\r
VOID\r
EFIAPI\r
AsmFxRestore (\r
  IN CONST IA32_FX_BUFFER *Buffer\r
  );\r
\r
VOID\r
EFIAPI\r
AsmFxSave (\r
  OUT IA32_FX_BUFFER *Buffer\r
  );\r
\r
UINTN\r
EFIAPI\r
AsmGetEflags (\r
  VOID\r
  );\r
\r
VOID\r
EFIAPI\r
AsmSetEflags (\r
  IN UINTN   Eflags\r
  );\r
\r
//\r
// Implementation\r
//\r
STATIC\r
IA32_REGISTER_SET *\r
AsmThunk16 (\r
  IN      THUNK_CONTEXT             *ThunkContext,\r
  IN OUT  IA32_REGISTER_SET         *RegisterSet,\r
  IN      UINT32                    ThunkFlags\r
  )\r
/*++\r
\r
Routine Description:\r
\r
  Do the 16-bit thunk code.\r
\r
  NOTE: This function must be called on TPL_HIGH_LEVEL or with interrupts\r
        disabled because of GDTR and IDTR manipulations.\r
        This function must be placed in identity mapped pages.\r
\r
Arguments:\r
\r
  ThunkContext  - Thunk context to use.\r
  RegisterSet   - CPU registers would be set to the values contained in this\r
                  structure before making the far call. Then CPU registers are\r
                  copied back to this structure.\r
                  SS:ESP points to the real mode stack if THUNK_USER_STACK is\r
                  set on input, otherwise ignored.\r
                  EFlages is ignored on input.\r
                  On output, values of CS, EIP, SS and ESP should be ignored.\r
  ThunkFlags    - 2 flags have currently been defined, THUNK_SAVE_FP_STATE and\r
                  THUNK_USER_STACK.\r
                  THUNK_SAVE_FP_STATE - FPU state would be saved/restored\r
                                        before/after calling real mode code.\r
                  THUNK_USER_STACK    - The stack specified by SS:ESP would be\r
                                        used instead of the default stack.\r
\r
Returns:\r
\r
  RegisterSet is returned.\r
\r
--*/\r
{\r
  IA32_FX_BUFFER                    *FpSavedState;\r
  UINT8                             FpBuffer[sizeof (*FpSavedState) + 0x10];\r
  UINTN                             Eflags;\r
\r
  FpSavedState = (IA32_FX_BUFFER*)(((UINTN)FpBuffer + 0xf) & ~0xf);\r
\r
  if (!(ThunkFlags & THUNK_USER_STACK)) {\r
    RegisterSet->E.ESP = (UINT16)ThunkContext->DefaultStack;\r
    RegisterSet->E.SS = (UINT16)((ThunkContext->DefaultStack >> 4) & 0xf000);\r
  }\r
\r
  if (ThunkFlags & THUNK_SAVE_FP_STATE) {\r
    AsmFxSave (FpSavedState);\r
  }\r
\r
  Eflags = AsmGetEflags ();\r
\r
  EfiCommonLibCopyMem (\r
    RegisterSet,\r
    _Thunk16 (\r
      RegisterSet,\r
      (UINT16)(ThunkFlags >> 16),\r
      ThunkContext->RealModeBuffer >> 4\r
      ),\r
    sizeof (*RegisterSet)\r
    );\r
\r
   AsmSetEflags (Eflags);\r
\r
  if (ThunkFlags & THUNK_SAVE_FP_STATE) {\r
    AsmFxRestore (FpSavedState);\r
  }\r
\r
  return RegisterSet;\r
}\r
\r
UINTN\r
EFIAPI\r
AsmThunk16GetProperties (\r
  OUT     UINTN                     *MinimumStackSize\r
  )\r
/*++\r
\r
Routine Description:\r
\r
  Returns the properties of this real mode thunk implementation. Currently\r
  there are 2 properties has been defined, the minimum real mode buffer size\r
  and the minimum stack size.\r
\r
Arguments:\r
\r
  MinimumStackSize  - The minimum size required for a 16-bit stack.\r
\r
Returns:\r
\r
  The minimum size of the real mode buffer needed by this thunk implementation\r
  is returned.\r
\r
--*/\r
{\r
  //\r
  // This size should be large enough to hold the register set as well as saved\r
  // CPU contexts including GDTR, CR0 and CR4\r
  //\r
  if (MinimumStackSize) {\r
    *MinimumStackSize = sizeof (IA32_REGISTER_SET) + 0x200;\r
  }\r
\r
  return mCode16Size;\r
}\r
\r
THUNK_CONTEXT *\r
EFIAPI\r
AsmThunk16SetProperties (\r
  OUT     THUNK_CONTEXT             *ThunkContext,\r
  IN      VOID                      *RealModeBuffer,\r
  IN      UINTN                     BufferSize\r
  )\r
/*++\r
\r
Routine Description:\r
\r
  Tell this real mode thunk implementation the address and size of the real\r
  mode buffer needed.\r
\r
Arguments:\r
\r
  ThunkContext    - The thunk context whose properties to set.\r
  RealModeBuffer  - The address of the buffer allocated by caller. It should be\r
                    aligned on a 16-byte boundary.\r
                    This buffer must be in identity mapped pages.\r
  BufferSize      - The size of RealModeBuffer. Must be larger than the minimum\r
                    size required as returned by AsmThunk16GetProperties().\r
\r
Returns:\r
\r
  None\r
\r
--*/\r
{\r
  BufferSize &= ~3;\r
\r
  ThunkContext->RealModeBuffer = (UINT32)(UINTN)RealModeBuffer;\r
  ThunkContext->DefaultStack   = (UINT32)(ThunkContext->RealModeBuffer + BufferSize);\r
  EfiCommonLibCopyMem (RealModeBuffer, (VOID*)(UINTN)_Code16Addr, mCode16Size);\r
\r
  return ThunkContext;\r
}\r
\r
#pragma pack (1)\r
\r
typedef struct {\r
  UINT32                            EDI;\r
  UINT32                            ESI;\r
  UINT32                            EBP;\r
  UINT32                            ESP;\r
  UINT32                            EBX;\r
  UINT32                            EDX;\r
  UINT32                            ECX;\r
  UINT32                            EAX;\r
  UINT16                            DS;\r
  UINT16                            ES;\r
  UINT16                            FS;\r
  UINT16                            GS;\r
  UINTN                             EFLAGS;\r
  UINT32                            EIP;\r
  UINT16                            CS;\r
  UINT16                            SS;\r
} IA32_REGS;\r
\r
typedef struct {\r
  UINT16  Limit;\r
  UINT32  Base;\r
} IA32_DESC;\r
\r
typedef struct {\r
  UINT32    RetEip;\r
  UINT16    RetCs;\r
  UINT16    ThunkFlags;\r
#ifdef EFI32\r
  UINT32    SavedEsp;\r
  UINT16    SavedSs;\r
#endif\r
  IA32_DESC SavedGdtr;\r
#ifdef EFIX64\r
  UINT16    Resvd1;\r
#endif\r
  UINT32    SavedCr0;\r
  UINT32    SavedCr4;\r
} _STK16;\r
#pragma pack ()\r
\r
#define STACK_PARAM_SIZE  16\r
\r
BOOLEAN\r
AsmThunk16SetUserStack (\r
  IN THUNK_CONTEXT             *ThunkContext,\r
  IN VOID                      *Stack,\r
  IN UINTN                     StackSize\r
  )\r
{\r
  if (StackSize > STACK_PARAM_SIZE) {\r
    return FALSE;\r
  }\r
\r
  EfiCommonLibCopyMem ((VOID *)(UINTN)(ThunkContext->DefaultStack - sizeof(_STK16) - sizeof(IA32_REGS) - STACK_PARAM_SIZE), Stack, StackSize);\r
\r
  return TRUE;\r
}\r
\r
VOID\r
EFIAPI\r
AsmThunk16Destroy (\r
  IN OUT  THUNK_CONTEXT             *ThunkContext\r
  )\r
/*++\r
\r
Routine Description:\r
\r
  Reset all internal states to their initial values. The caller should not\r
  release the real mode buffer until after a call to this function.\r
\r
Arguments:\r
\r
  ThunkContext  - The thunk context to destroy.\r
\r
Returns:\r
\r
  None\r
\r
--*/\r
{\r
  ThunkContext->RealModeBuffer = 0;\r
}\r
\r
IA32_REGISTER_SET *\r
EFIAPI\r
AsmThunk16FarCall86 (\r
  IN      THUNK_CONTEXT             *ThunkContext,\r
  IN OUT  IA32_REGISTER_SET         *RegisterSet,\r
  IN      UINT32                    Flags\r
  )\r
/*++\r
\r
Routine Description:\r
\r
  Make a far call to 16-bit code.\r
\r
  NOTE: This function must be called on TPL_HIGH_LEVEL or with interrupts\r
        disabled because of GDTR and IDTR manipulations.\r
        This function must be placed in identity mapped pages.\r
\r
Arguments:\r
\r
  ThunkContext  - Thunk context to use.\r
  RegisterSet   - CPU registers would be set to the values contained in this\r
                  structure before making the far call. Then CPU registers are\r
                  copied back to this structure.\r
                  CS:EIP points to the real mode code being called on input.\r
                  SS:ESP points to the real mode stack if THUNK_USER_STACK is\r
                  set on input, otherwise ignored.\r
                  EFlages is ignored on input.\r
                  On output, values of CS, EIP, SS and ESP should be ignored.\r
  ThunkFlags    - THUNK_USER_STACK: The stack specified by SS:ESP would be\r
                  used instead of the default stack.\r
\r
Returns:\r
\r
  RegisterSet is returned.\r
\r
--*/\r
{\r
  return AsmThunk16 (ThunkContext, RegisterSet, Flags);\r
}\r
\r
IA32_REGISTER_SET *\r
EFIAPI\r
AsmThunk16Int86 (\r
  IN      THUNK_CONTEXT             *ThunkContext,\r
  IN      UINT8                     IntNumber,\r
  IN OUT  IA32_REGISTER_SET         *RegisterSet,\r
  IN      UINT32                    Flags\r
  )\r
/*++\r
\r
Routine Description:\r
\r
  Invoke a 16-bit interrupt handler.\r
\r
  NOTE: This function must be called on TPL_HIGH_LEVEL or with interrupts\r
        disabled because of GDTR and IDTR manipulations.\r
        This function must be placed in identity mapped pages.\r
\r
Arguments:\r
\r
  ThunkContext  - Thunk context to use.\r
  IntNumber     - The ordinal of the interrupt handler ranging from 0 to 255.\r
  RegisterSet   - CPU registers would be set to the values contained in this\r
                  structure before making the far call. Then CPU registers are\r
                  copied back to this structure.\r
                  SS:ESP points to the real mode stack if THUNK_USER_STACK is\r
                  set on input, otherwise ignored.\r
                  EFlages is ignored on input.\r
                  On output, values of CS, EIP, SS and ESP should be ignored.\r
  ThunkFlags    - THUNK_USER_STACK: The stack specified by SS:ESP would be\r
                  used instead of the default stack.\r
\r
Returns:\r
\r
  RegisterSet is returned.\r
\r
--*/\r
{\r
  UINT32  *VectorBase;\r
  \r
  //\r
  // The base address of legacy interrupt vector table is 0.\r
  // We use this base address to get the legacy interrupt handler.\r
  //\r
  VectorBase = 0;\r
  RegisterSet->E.EIP = (UINT16)(VectorBase)[IntNumber];\r
  RegisterSet->E.CS  = (UINT16)((VectorBase)[IntNumber] >> 16);\r
\r
  return AsmThunk16 (ThunkContext, RegisterSet, Flags | THUNK_INTERRUPT);\r
}\r
Commit	Line	Data
3eb9473e	1	/*++\r
3eb9473e	2	\r
515327a3	3	Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>\r
4ea9375a	4	This program and the accompanying materials \r
3eb9473e	5	are licensed and made available under the terms and conditions of the BSD License \r
	6	which accompanies this distribution. The full text of the license may be found at \r
	7	http://opensource.org/licenses/bsd-license.php \r
	8	\r
	9	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r
	10	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r
	11	\r
	12	\r
	13	Module Name:\r
	14	\r
	15	x86Thunk.c\r
	16	\r
	17	Abstract:\r
	18	\r
	19	Real Mode Thunk Functions\r
	20	\r
	21	--*/\r
	22	\r
	23	#include "Thunk16Lib.h"\r
	24	#include "EfiCommonLib.h"\r
	25	\r
3eb9473e	26	extern CONST UINTN mCode16Size;\r
	27	\r
	28	extern\r
	29	IA32_REGISTER_SET *\r
4798ea5b	30	EFIAPI\r
3eb9473e	31	_Thunk16 (\r
	32	IN OUT IA32_REGISTER_SET *RegisterSet,\r
	33	IN UINT32 ThunkFlags,\r
	34	IN UINT32 RealModeCs\r
	35	);\r
	36	\r
	37	extern\r
	38	VOID\r
4798ea5b	39	EFIAPI\r
3eb9473e	40	_Code16Addr (\r
	41	VOID\r
	42	);\r
	43	\r
	44	VOID\r
4798ea5b	45	EFIAPI\r
3eb9473e	46	AsmFxRestore (\r
	47	IN CONST IA32_FX_BUFFER *Buffer\r
	48	);\r
	49	\r
	50	VOID\r
4798ea5b	51	EFIAPI\r
3eb9473e	52	AsmFxSave (\r
	53	OUT IA32_FX_BUFFER *Buffer\r
	54	);\r
	55	\r
3e99020d LG	56	UINTN\r
	57	EFIAPI\r
	58	AsmGetEflags (\r
	59	VOID\r
	60	);\r
	61	\r
	62	VOID\r
	63	EFIAPI\r
	64	AsmSetEflags (\r
	65	IN UINTN Eflags\r
	66	);\r
	67	\r
3eb9473e	68	//\r
	69	// Implementation\r
	70	//\r
	71	STATIC\r
	72	IA32_REGISTER_SET *\r
	73	AsmThunk16 (\r
	74	IN THUNK_CONTEXT *ThunkContext,\r
	75	IN OUT IA32_REGISTER_SET *RegisterSet,\r
	76	IN UINT32 ThunkFlags\r
	77	)\r
	78	/*++\r
	79	\r
	80	Routine Description:\r
	81	\r
	82	Do the 16-bit thunk code.\r
	83	\r
	84	NOTE: This function must be called on TPL_HIGH_LEVEL or with interrupts\r
	85	disabled because of GDTR and IDTR manipulations.\r
	86	This function must be placed in identity mapped pages.\r
	87	\r
	88	Arguments:\r
	89	\r
	90	ThunkContext - Thunk context to use.\r
	91	RegisterSet - CPU registers would be set to the values contained in this\r
	92	structure before making the far call. Then CPU registers are\r
	93	copied back to this structure.\r
	94	SS:ESP points to the real mode stack if THUNK_USER_STACK is\r
	95	set on input, otherwise ignored.\r
	96	EFlages is ignored on input.\r
	97	On output, values of CS, EIP, SS and ESP should be ignored.\r
	98	ThunkFlags - 2 flags have currently been defined, THUNK_SAVE_FP_STATE and\r
	99	THUNK_USER_STACK.\r
	100	THUNK_SAVE_FP_STATE - FPU state would be saved/restored\r
	101	before/after calling real mode code.\r
	102	THUNK_USER_STACK - The stack specified by SS:ESP would be\r
	103	used instead of the default stack.\r
	104	\r
	105	Returns:\r
	106	\r
	107	RegisterSet is returned.\r
	108	\r
	109	--*/\r
	110	{\r
	111	IA32_FX_BUFFER *FpSavedState;\r
	112	UINT8 FpBuffer[sizeof (*FpSavedState) + 0x10];\r
3e99020d	113	UINTN Eflags;\r
3eb9473e	114	\r
	115	FpSavedState = (IA32_FX_BUFFER*)(((UINTN)FpBuffer + 0xf) & ~0xf);\r
	116	\r
	117	if (!(ThunkFlags & THUNK_USER_STACK)) {\r
	118	RegisterSet->E.ESP = (UINT16)ThunkContext->DefaultStack;\r
	119	RegisterSet->E.SS = (UINT16)((ThunkContext->DefaultStack >> 4) & 0xf000);\r
	120	}\r
	121	\r
	122	if (ThunkFlags & THUNK_SAVE_FP_STATE) {\r
	123	AsmFxSave (FpSavedState);\r
	124	}\r
	125	\r
3e99020d LG	126	Eflags = AsmGetEflags ();\r
3e99020d LG	127	\r
3eb9473e	128	EfiCommonLibCopyMem (\r
	129	RegisterSet,\r
	130	_Thunk16 (\r
	131	RegisterSet,\r
	132	(UINT16)(ThunkFlags >> 16),\r
	133	ThunkContext->RealModeBuffer >> 4\r
	134	),\r
	135	sizeof (*RegisterSet)\r
	136	);\r
	137	\r
3e99020d LG	138	AsmSetEflags (Eflags);\r
3e99020d LG	139	\r
3eb9473e	140	if (ThunkFlags & THUNK_SAVE_FP_STATE) {\r
	141	AsmFxRestore (FpSavedState);\r
	142	}\r
	143	\r
	144	return RegisterSet;\r
	145	}\r
	146	\r
	147	UINTN\r
	148	EFIAPI\r
	149	AsmThunk16GetProperties (\r
	150	OUT UINTN *MinimumStackSize\r
	151	)\r
	152	/*++\r
	153	\r
	154	Routine Description:\r
	155	\r
	156	Returns the properties of this real mode thunk implementation. Currently\r
	157	there are 2 properties has been defined, the minimum real mode buffer size\r
	158	and the minimum stack size.\r
	159	\r
	160	Arguments:\r
	161	\r
	162	MinimumStackSize - The minimum size required for a 16-bit stack.\r
	163	\r
	164	Returns:\r
	165	\r
	166	The minimum size of the real mode buffer needed by this thunk implementation\r
	167	is returned.\r
	168	\r
	169	--*/\r
	170	{\r
	171	//\r
	172	// This size should be large enough to hold the register set as well as saved\r
	173	// CPU contexts including GDTR, CR0 and CR4\r
	174	//\r
	175	if (MinimumStackSize) {\r
	176	*MinimumStackSize = sizeof (IA32_REGISTER_SET) + 0x200;\r
	177	}\r
	178	\r
	179	return mCode16Size;\r
	180	}\r
	181	\r
	182	THUNK_CONTEXT *\r
	183	EFIAPI\r
	184	AsmThunk16SetProperties (\r
	185	OUT THUNK_CONTEXT *ThunkContext,\r
	186	IN VOID *RealModeBuffer,\r
	187	IN UINTN BufferSize\r
	188	)\r
	189	/*++\r
	190	\r
	191	Routine Description:\r
	192	\r
	193	Tell this real mode thunk implementation the address and size of the real\r
	194	mode buffer needed.\r
	195	\r
	196	Arguments:\r
	197	\r
	198	ThunkContext - The thunk context whose properties to set.\r
	199	RealModeBuffer - The address of the buffer allocated by caller. It should be\r
	200	aligned on a 16-byte boundary.\r
	201	This buffer must be in identity mapped pages.\r
	202	BufferSize - The size of RealModeBuffer. Must be larger than the minimum\r
	203	size required as returned by AsmThunk16GetProperties().\r
204	\r
205	Returns:\r
206	\r
207	None\r
208	\r
209	--*/\r
210	{\r
211	BufferSize &= ~3;\r
212	\r
213	ThunkContext->RealModeBuffer = (UINT32)(UINTN)RealModeBuffer;\r
214	ThunkContext->DefaultStack = (UINT32)(ThunkContext->RealModeBuffer + BufferSize);\r
215	EfiCommonLibCopyMem (RealModeBuffer, (VOID*)(UINTN)_Code16Addr, mCode16Size);\r
216	\r
217	return ThunkContext;\r
218	}\r
219	\r
3e99020d LG	220	#pragma pack (1)\r
	221	\r
	222	typedef struct {\r
	223	UINT32 EDI;\r
	224	UINT32 ESI;\r
	225	UINT32 EBP;\r
	226	UINT32 ESP;\r
	227	UINT32 EBX;\r
	228	UINT32 EDX;\r
	229	UINT32 ECX;\r
	230	UINT32 EAX;\r
	231	UINT16 DS;\r
	232	UINT16 ES;\r
	233	UINT16 FS;\r
	234	UINT16 GS;\r
	235	UINTN EFLAGS;\r
	236	UINT32 EIP;\r
	237	UINT16 CS;\r
	238	UINT16 SS;\r
	239	} IA32_REGS;\r
	240	\r
	241	typedef struct {\r
	242	UINT16 Limit;\r
	243	UINT32 Base;\r
	244	} IA32_DESC;\r
	245	\r
	246	typedef struct {\r
	247	UINT32 RetEip;\r
	248	UINT16 RetCs;\r
	249	UINT16 ThunkFlags;\r
	250	#ifdef EFI32\r
	251	UINT32 SavedEsp;\r
	252	UINT16 SavedSs;\r
	253	#endif\r
	254	IA32_DESC SavedGdtr;\r
	255	#ifdef EFIX64\r
	256	UINT16 Resvd1;\r
	257	#endif\r
	258	UINT32 SavedCr0;\r
	259	UINT32 SavedCr4;\r
	260	} _STK16;\r
	261	#pragma pack ()\r
	262	\r
	263	#define STACK_PARAM_SIZE 16\r
	264	\r
	265	BOOLEAN\r
	266	AsmThunk16SetUserStack (\r
	267	IN THUNK_CONTEXT *ThunkContext,\r
	268	IN VOID *Stack,\r
	269	IN UINTN StackSize\r
	270	)\r
	271	{\r
	272	if (StackSize > STACK_PARAM_SIZE) {\r
	273	return FALSE;\r
	274	}\r
	275	\r
	276	EfiCommonLibCopyMem ((VOID *)(UINTN)(ThunkContext->DefaultStack - sizeof(_STK16) - sizeof(IA32_REGS) - STACK_PARAM_SIZE), Stack, StackSize);\r
	277	\r
	278	return TRUE;\r
	279	}\r
	280	\r
3eb9473e	281	VOID\r
	282	EFIAPI\r
	283	AsmThunk16Destroy (\r
	284	IN OUT THUNK_CONTEXT *ThunkContext\r
	285	)\r
	286	/*++\r
	287	\r
	288	Routine Description:\r
	289	\r
	290	Reset all internal states to their initial values. The caller should not\r
	291	release the real mode buffer until after a call to this function.\r
	292	\r
	293	Arguments:\r
	294	\r
	295	ThunkContext - The thunk context to destroy.\r
	296	\r
	297	Returns:\r
	298	\r
	299	None\r
	300	\r
	301	--*/\r
	302	{\r
	303	ThunkContext->RealModeBuffer = 0;\r
	304	}\r
	305	\r
	306	IA32_REGISTER_SET *\r
	307	EFIAPI\r
	308	AsmThunk16FarCall86 (\r
	309	IN THUNK_CONTEXT *ThunkContext,\r
	310	IN OUT IA32_REGISTER_SET *RegisterSet,\r
	311	IN UINT32 Flags\r
	312	)\r
	313	/*++\r
	314	\r
	315	Routine Description:\r
	316	\r
	317	Make a far call to 16-bit code.\r
	318	\r
	319	NOTE: This function must be called on TPL_HIGH_LEVEL or with interrupts\r
	320	disabled because of GDTR and IDTR manipulations.\r
	321	This function must be placed in identity mapped pages.\r
	322	\r
	323	Arguments:\r
	324	\r
	325	ThunkContext - Thunk context to use.\r
	326	RegisterSet - CPU registers would be set to the values contained in this\r
	327	structure before making the far call. Then CPU registers are\r
	328	copied back to this structure.\r
	329	CS:EIP points to the real mode code being called on input.\r
	330	SS:ESP points to the real mode stack if THUNK_USER_STACK is\r
	331	set on input, otherwise ignored.\r
	332	EFlages is ignored on input.\r
	333	On output, values of CS, EIP, SS and ESP should be ignored.\r
3e99020d LG	334	ThunkFlags - THUNK_USER_STACK: The stack specified by SS:ESP would be\r
3e99020d LG	335	used instead of the default stack.\r
3eb9473e	336	\r
	337	Returns:\r
	338	\r
	339	RegisterSet is returned.\r
	340	\r
	341	--*/\r
	342	{\r
	343	return AsmThunk16 (ThunkContext, RegisterSet, Flags);\r
	344	}\r
	345	\r
	346	IA32_REGISTER_SET *\r
	347	EFIAPI\r
	348	AsmThunk16Int86 (\r
	349	IN THUNK_CONTEXT *ThunkContext,\r
	350	IN UINT8 IntNumber,\r
	351	IN OUT IA32_REGISTER_SET *RegisterSet,\r
	352	IN UINT32 Flags\r
	353	)\r
	354	/*++\r
	355	\r
	356	Routine Description:\r
	357	\r
	358	Invoke a 16-bit interrupt handler.\r
	359	\r
	360	NOTE: This function must be called on TPL_HIGH_LEVEL or with interrupts\r
	361	disabled because of GDTR and IDTR manipulations.\r
	362	This function must be placed in identity mapped pages.\r
	363	\r
	364	Arguments:\r
	365	\r
	366	ThunkContext - Thunk context to use.\r
	367	IntNumber - The ordinal of the interrupt handler ranging from 0 to 255.\r
	368	RegisterSet - CPU registers would be set to the values contained in this\r
	369	structure before making the far call. Then CPU registers are\r
	370	copied back to this structure.\r
	371	SS:ESP points to the real mode stack if THUNK_USER_STACK is\r
	372	set on input, otherwise ignored.\r
	373	EFlages is ignored on input.\r
	374	On output, values of CS, EIP, SS and ESP should be ignored.\r
3e99020d LG	375	ThunkFlags - THUNK_USER_STACK: The stack specified by SS:ESP would be\r
3e99020d LG	376	used instead of the default stack.\r
3eb9473e	377	\r
	378	Returns:\r
	379	\r
	380	RegisterSet is returned.\r
	381	\r
	382	--*/\r
	383	{\r
515327a3	384	UINT32 *VectorBase;\r
	385	\r
	386	//\r
	387	// The base address of legacy interrupt vector table is 0.\r
	388	// We use this base address to get the legacy interrupt handler.\r
	389	//\r
	390	VectorBase = 0;\r
	391	RegisterSet->E.EIP = (UINT16)(VectorBase)[IntNumber];\r
	392	RegisterSet->E.CS = (UINT16)((VectorBase)[IntNumber] >> 16);\r
3eb9473e	393	\r
	394	return AsmThunk16 (ThunkContext, RegisterSet, Flags \| THUNK_INTERRUPT);\r
	395	}\r