[mirror_edk2.git] / IntelFrameworkModulePkg / Csm / LegacyBiosDxe / Thunk.c

/** @file\r
  Call into 16-bit BIOS code, Use AsmThunk16 function of BaseLib.\r
\r
Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>\r
\r
This program and the accompanying materials\r
are licensed and made available under the terms and conditions\r
of the BSD License which accompanies this distribution.  The\r
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
\r
#include "LegacyBiosInterface.h"\r
\r
THUNK_CONTEXT      mThunkContext;\r
\r
/**\r
  Sets the counter value for Timer #0 in a legacy 8254 timer.\r
\r
  @param  Count - The 16-bit counter value to program into Timer #0 of the legacy 8254 timer.\r
\r
**/\r
VOID\r
SetPitCount (\r
  IN UINT16  Count\r
  )\r
{\r
  IoWrite8 (TIMER_CONTROL_PORT, TIMER0_CONTROL_WORD);\r
  IoWrite8 (TIMER0_COUNT_PORT, (UINT8) (Count & 0xFF));\r
  IoWrite8 (TIMER0_COUNT_PORT, (UINT8) ((Count>>8) & 0xFF));\r
}\r
\r
/**\r
  Thunk to 16-bit real mode and execute a software interrupt with a vector\r
  of BiosInt. Regs will contain the 16-bit register context on entry and\r
  exit.\r
\r
  @param  This    Protocol instance pointer.\r
  @param  BiosInt Processor interrupt vector to invoke\r
  @param  Regs    Register contexted passed into (and returned) from thunk to\r
                  16-bit mode\r
\r
  @retval FALSE   Thunk completed, and there were no BIOS errors in the target code.\r
                  See Regs for status.\r
  @retval TRUE    There was a BIOS erro in the target code.\r
\r
**/\r
BOOLEAN\r
EFIAPI\r
LegacyBiosInt86 (\r
  IN  EFI_LEGACY_BIOS_PROTOCOL      *This,\r
  IN  UINT8                         BiosInt,\r
  IN  EFI_IA32_REGISTER_SET         *Regs\r
  )\r
{\r
  UINT32  *VectorBase;\r
\r
  Regs->X.Flags.Reserved1 = 1;\r
  Regs->X.Flags.Reserved2 = 0;\r
  Regs->X.Flags.Reserved3 = 0;\r
  Regs->X.Flags.Reserved4 = 0;\r
  Regs->X.Flags.IOPL      = 3;\r
  Regs->X.Flags.NT        = 0;\r
  Regs->X.Flags.IF        = 0;\r
  Regs->X.Flags.TF        = 0;\r
  Regs->X.Flags.CF        = 0;\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
  \r
  return InternalLegacyBiosFarCall (\r
           This,\r
           (UINT16) ((VectorBase)[BiosInt] >> 16),\r
           (UINT16) (VectorBase)[BiosInt],\r
           Regs,\r
           &Regs->X.Flags,\r
           sizeof (Regs->X.Flags)\r
           );\r
}\r
\r
/**\r
  Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the\r
  16-bit register context on entry and exit. Arguments can be passed on\r
  the Stack argument\r
\r
  @param  This                   Protocol instance pointer.\r
  @param  Segment                Segemnt of 16-bit mode call\r
  @param  Offset                 Offset of 16-bit mdoe call\r
  @param  Regs                   Register contexted passed into (and returned) from\r
                                 thunk to  16-bit mode\r
  @param  Stack                  Caller allocated stack used to pass arguments\r
  @param  StackSize              Size of Stack in bytes\r
\r
  @retval FALSE                  Thunk completed, and there were no BIOS errors in\r
                                 the target code. See Regs for status.\r
  @retval TRUE                   There was a BIOS erro in the target code.\r
\r
**/\r
BOOLEAN\r
EFIAPI\r
LegacyBiosFarCall86 (\r
  IN  EFI_LEGACY_BIOS_PROTOCOL        *This,\r
  IN  UINT16                          Segment,\r
  IN  UINT16                          Offset,\r
  IN  EFI_IA32_REGISTER_SET           *Regs,\r
  IN  VOID                            *Stack,\r
  IN  UINTN                           StackSize\r
  )\r
{\r
  Regs->X.Flags.Reserved1 = 1;\r
  Regs->X.Flags.Reserved2 = 0;\r
  Regs->X.Flags.Reserved3 = 0;\r
  Regs->X.Flags.Reserved4 = 0;\r
  Regs->X.Flags.IOPL      = 3;\r
  Regs->X.Flags.NT        = 0;\r
  Regs->X.Flags.IF        = 1;\r
  Regs->X.Flags.TF        = 0;\r
  Regs->X.Flags.CF        = 0;\r
\r
  return InternalLegacyBiosFarCall (This, Segment, Offset, Regs, Stack, StackSize);\r
}\r
\r
/**\r
  Provide NULL interrupt handler which is used to check \r
  if there is more than one HW interrupt registers with the CPU AP.\r
\r
  @param  InterruptType - The type of interrupt that occured\r
  @param  SystemContext - A pointer to the system context when the interrupt occured\r
\r
**/\r
VOID\r
EFIAPI\r
LegacyBiosNullInterruptHandler (\r
  IN EFI_EXCEPTION_TYPE   InterruptType,\r
  IN EFI_SYSTEM_CONTEXT   SystemContext\r
  )\r
{\r
}\r
\r
/**\r
  Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the\r
  16-bit register context on entry and exit. Arguments can be passed on\r
  the Stack argument\r
\r
  @param  This       Protocol instance pointer.\r
  @param  Segment    Segemnt of 16-bit mode call\r
  @param  Offset     Offset of 16-bit mdoe call\r
  @param  Regs       Register contexted passed into (and returned) from thunk to\r
                     16-bit mode\r
  @param  Stack      Caller allocated stack used to pass arguments\r
  @param  StackSize  Size of Stack in bytes\r
\r
  @retval FALSE      Thunk completed, and there were no BIOS errors in the target code.\r
                     See Regs for status.\r
  @retval TRUE       There was a BIOS erro in the target code.\r
\r
**/\r
BOOLEAN\r
EFIAPI\r
InternalLegacyBiosFarCall (\r
  IN  EFI_LEGACY_BIOS_PROTOCOL        *This,\r
  IN  UINT16                          Segment,\r
  IN  UINT16                          Offset,\r
  IN  EFI_IA32_REGISTER_SET           *Regs,\r
  IN  VOID                            *Stack,\r
  IN  UINTN                           StackSize\r
  )\r
{\r
  UINTN                 Status;\r
  LEGACY_BIOS_INSTANCE  *Private;\r
  UINT16                *Stack16;\r
  EFI_TPL               OriginalTpl;\r
  IA32_REGISTER_SET     ThunkRegSet;\r
  BOOLEAN               InterruptState;\r
  UINT64                TimerPeriod;\r
\r
  Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);\r
\r
  ZeroMem (&ThunkRegSet, sizeof (ThunkRegSet));\r
  ThunkRegSet.X.DI   = Regs->X.DI;\r
  ThunkRegSet.X.SI   = Regs->X.SI;\r
  ThunkRegSet.X.BP   = Regs->X.BP;\r
  ThunkRegSet.X.BX   = Regs->X.BX;\r
  ThunkRegSet.X.DX   = Regs->X.DX;\r
  //\r
  // Sometimes, ECX is used to pass in 32 bit data. For example, INT 1Ah, AX = B10Dh is\r
  // "PCI BIOS v2.0c + Write Configuration DWORD" and ECX has the dword to write.\r
  //\r
  ThunkRegSet.E.ECX   = Regs->E.ECX;\r
  ThunkRegSet.X.AX   = Regs->X.AX;\r
  ThunkRegSet.E.DS   = Regs->X.DS;\r
  ThunkRegSet.E.ES   = Regs->X.ES;\r
\r
  CopyMem (&(ThunkRegSet.E.EFLAGS.UintN), &(Regs->X.Flags), sizeof (Regs->X.Flags));\r
\r
  //\r
  // Clear the error flag; thunk code may set it. Stack16 should be the high address\r
  // Make Statk16 address the low 16 bit must be not zero.\r
  //\r
  Stack16 = (UINT16 *)((UINT8 *) mThunkContext.RealModeBuffer + mThunkContext.RealModeBufferSize - sizeof (UINT16));\r
\r
  //\r
  // Save current rate of DXE Timer\r
  //\r
  Private->Timer->GetTimerPeriod (Private->Timer, &TimerPeriod);\r
\r
  //\r
  // Disable DXE Timer while executing in real mode\r
  //\r
  Private->Timer->SetTimerPeriod (Private->Timer, 0);\r
 \r
  //\r
  // Save and disable interrupt of debug timer\r
  //\r
  InterruptState = SaveAndSetDebugTimerInterrupt (FALSE);\r
\r
  //\r
  // The call to Legacy16 is a critical section to EFI\r
  //\r
  OriginalTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
\r
  //\r
  // Check to see if there is more than one HW interrupt registers with the CPU AP.\r
  // If there is, then ASSERT() since that is not compatible with the CSM because \r
  // interupts other than the Timer interrupt that was disabled above can not be \r
  // handled properly from real mode.\r
  //\r
  DEBUG_CODE (\r
    UINTN  Vector;\r
    UINTN  Count;\r
    \r
    for (Vector = 0x20, Count = 0; Vector < 0x100; Vector++) {\r
      Status = Private->Cpu->RegisterInterruptHandler (Private->Cpu, Vector, LegacyBiosNullInterruptHandler);\r
      if (Status == EFI_ALREADY_STARTED) {\r
        Count++;\r
      }\r
      if (Status == EFI_SUCCESS) {\r
        Private->Cpu->RegisterInterruptHandler (Private->Cpu, Vector, NULL);\r
      }\r
    }\r
    if (Count >= 2) {\r
      DEBUG ((EFI_D_ERROR, "ERROR: More than one HW interrupt active with CSM enabled\n"));\r
    }\r
    ASSERT (Count < 2);\r
  );\r
\r
  //\r
  // If the Timer AP has enabled the 8254 timer IRQ and the current 8254 timer \r
  // period is less than the CSM required rate of 54.9254, then force the 8254 \r
  // PIT counter to 0, which is the CSM required rate of 54.9254 ms\r
  //\r
  if (Private->TimerUses8254 && TimerPeriod < 549254) {\r
    SetPitCount (0);\r
  }\r
  \r
  if (Stack != NULL && StackSize != 0) {\r
    //\r
    // Copy Stack to low memory stack\r
    //\r
    Stack16 -= StackSize / sizeof (UINT16);\r
    CopyMem (Stack16, Stack, StackSize);\r
  }\r
\r
  ThunkRegSet.E.SS   = (UINT16) (((UINTN) Stack16 >> 16) << 12);\r
  ThunkRegSet.E.ESP  = (UINT16) (UINTN) Stack16;\r
  ThunkRegSet.E.CS   = Segment;\r
  ThunkRegSet.E.Eip  = Offset;\r
\r
  mThunkContext.RealModeState      = &ThunkRegSet;\r
\r
  //\r
  // Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.\r
  //\r
  Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259LegacyMode, NULL, NULL);\r
  ASSERT_EFI_ERROR (Status);\r
\r
  AsmThunk16 (&mThunkContext);\r
\r
  //\r
  // OPROM may allocate EBDA range by itself and change EBDA base and EBDA size.\r
  // Get the current EBDA base address, and compared with pre-allocate minimum\r
  // EBDA base address, if the current EBDA base address is smaller, it indicates\r
  // PcdEbdaReservedMemorySize should be adjusted to larger for more OPROMs.\r
  //\r
  DEBUG_CODE (\r
    {\r
      UINTN                 EbdaBaseAddress;\r
      UINTN                 ReservedEbdaBaseAddress;\r
\r
      EbdaBaseAddress = (*(UINT16 *) (UINTN) 0x40E) << 4;\r
      ReservedEbdaBaseAddress = CONVENTIONAL_MEMORY_TOP - PcdGet32 (PcdEbdaReservedMemorySize);\r
      ASSERT (ReservedEbdaBaseAddress <= EbdaBaseAddress);\r
    }\r
  );\r
\r
  if (Stack != NULL && StackSize != 0) {\r
    //\r
    // Copy low memory stack to Stack\r
    //\r
    CopyMem (Stack, Stack16, StackSize);\r
  }\r
\r
  //\r
  // Restore protected mode interrupt state\r
  //\r
  Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259ProtectedMode, NULL, NULL);\r
  ASSERT_EFI_ERROR (Status);\r
\r
  mThunkContext.RealModeState = NULL;\r
\r
  //\r
  // Enable and restore rate of DXE Timer\r
  //\r
  Private->Timer->SetTimerPeriod (Private->Timer, TimerPeriod);\r
\r
  //\r
  // End critical section\r
  //\r
  gBS->RestoreTPL (OriginalTpl);\r
  \r
  //\r
  // Restore interrupt of debug timer\r
  //\r
  SaveAndSetDebugTimerInterrupt (InterruptState);\r
\r
  Regs->E.EDI      = ThunkRegSet.E.EDI;\r
  Regs->E.ESI      = ThunkRegSet.E.ESI;\r
  Regs->E.EBP      = ThunkRegSet.E.EBP;\r
  Regs->E.EBX      = ThunkRegSet.E.EBX;\r
  Regs->E.EDX      = ThunkRegSet.E.EDX;\r
  Regs->E.ECX      = ThunkRegSet.E.ECX;\r
  Regs->E.EAX      = ThunkRegSet.E.EAX;\r
  Regs->X.SS       = ThunkRegSet.E.SS;\r
  Regs->X.CS       = ThunkRegSet.E.CS;\r
  Regs->X.DS       = ThunkRegSet.E.DS;\r
  Regs->X.ES       = ThunkRegSet.E.ES;\r
\r
  CopyMem (&(Regs->X.Flags), &(ThunkRegSet.E.EFLAGS.UintN), sizeof (Regs->X.Flags));\r
\r
  return (BOOLEAN) (Regs->X.Flags.CF == 1);\r
}\r
\r
/**\r
  Allocate memory < 1 MB and copy the thunker code into low memory. Se up\r
  all the descriptors.\r
\r
  @param  Private                Private context for Legacy BIOS\r
\r
  @retval EFI_SUCCESS            Should only pass.\r
\r
**/\r
EFI_STATUS\r
LegacyBiosInitializeThunk (\r
  IN  LEGACY_BIOS_INSTANCE    *Private\r
  )\r
{\r
  EFI_STATUS              Status;\r
  EFI_PHYSICAL_ADDRESS    MemoryAddress;\r
  UINT8                   TimerVector;\r
\r
  MemoryAddress   = (EFI_PHYSICAL_ADDRESS) (UINTN) Private->IntThunk;\r
\r
  mThunkContext.RealModeBuffer     = (VOID *) (UINTN) (MemoryAddress + ((sizeof (LOW_MEMORY_THUNK) / EFI_PAGE_SIZE) + 1) * EFI_PAGE_SIZE);\r
  mThunkContext.RealModeBufferSize = EFI_PAGE_SIZE;\r
  mThunkContext.ThunkAttributes    = THUNK_ATTRIBUTE_BIG_REAL_MODE | THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15;\r
\r
  AsmPrepareThunk16 (&mThunkContext);\r
\r
  //\r
  // Get the interrupt vector number corresponding to IRQ0 from the 8259 driver\r
  //\r
  TimerVector = 0;\r
  Status = Private->Legacy8259->GetVector (Private->Legacy8259, Efi8259Irq0, &TimerVector);\r
  ASSERT_EFI_ERROR (Status);\r
  \r
  //\r
  // Check to see if the Timer AP has hooked the IRQ0 from the 8254 PIT\r
  //  \r
  Status = Private->Cpu->RegisterInterruptHandler (\r
                           Private->Cpu, \r
                           TimerVector, \r
                           LegacyBiosNullInterruptHandler\r
                           );\r
  if (Status == EFI_SUCCESS) {\r
    //\r
    // If the Timer AP has not enabled the 8254 timer IRQ, then force the 8254 PIT \r
    // counter to 0, which is the CSM required rate of 54.9254 ms\r
    //\r
    Private->Cpu->RegisterInterruptHandler (\r
                    Private->Cpu, \r
                    TimerVector, \r
                    NULL\r
                    );\r
    SetPitCount (0);\r
    \r
    //\r
    // Save status that the Timer AP is not using the 8254 PIT\r
    //\r
    Private->TimerUses8254 = FALSE;\r
  } else if (Status == EFI_ALREADY_STARTED) {\r
    //\r
    // Save status that the Timer AP is using the 8254 PIT\r
    //\r
    Private->TimerUses8254 = TRUE;\r
  } else {\r
    //\r
    // Unexpected status from CPU AP RegisterInterruptHandler()\r
    //\r
    ASSERT (FALSE);\r
  }\r
  \r
  return EFI_SUCCESS;\r
}\r
Commit	Line	Data
bcecde14	1	/** @file\r
	2	Call into 16-bit BIOS code, Use AsmThunk16 function of BaseLib.\r
	3	\r
f767f990	4	Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>\r
bcecde14	5	\r
	6	This program and the accompanying materials\r
	7	are licensed and made available under the terms and conditions\r
	8	of the BSD License which accompanies this distribution. The\r
	9	full text of the license may be found at\r
	10	http://opensource.org/licenses/bsd-license.php\r
	11	\r
	12	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
	13	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
	14	\r
	15	**/\r
	16	\r
	17	#include "LegacyBiosInterface.h"\r
	18	\r
	19	THUNK_CONTEXT mThunkContext;\r
	20	\r
f767f990	21	/**\r
	22	Sets the counter value for Timer #0 in a legacy 8254 timer.\r
	23	\r
	24	@param Count - The 16-bit counter value to program into Timer #0 of the legacy 8254 timer.\r
	25	\r
	26	**/\r
	27	VOID\r
	28	SetPitCount (\r
	29	IN UINT16 Count\r
	30	)\r
	31	{\r
	32	IoWrite8 (TIMER_CONTROL_PORT, TIMER0_CONTROL_WORD);\r
	33	IoWrite8 (TIMER0_COUNT_PORT, (UINT8) (Count & 0xFF));\r
	34	IoWrite8 (TIMER0_COUNT_PORT, (UINT8) ((Count>>8) & 0xFF));\r
	35	}\r
	36	\r
bcecde14	37	/**\r
	38	Thunk to 16-bit real mode and execute a software interrupt with a vector\r
	39	of BiosInt. Regs will contain the 16-bit register context on entry and\r
	40	exit.\r
	41	\r
	42	@param This Protocol instance pointer.\r
	43	@param BiosInt Processor interrupt vector to invoke\r
	44	@param Regs Register contexted passed into (and returned) from thunk to\r
	45	16-bit mode\r
	46	\r
	47	@retval FALSE Thunk completed, and there were no BIOS errors in the target code.\r
	48	See Regs for status.\r
	49	@retval TRUE There was a BIOS erro in the target code.\r
	50	\r
	51	**/\r
	52	BOOLEAN\r
	53	EFIAPI\r
	54	LegacyBiosInt86 (\r
	55	IN EFI_LEGACY_BIOS_PROTOCOL *This,\r
	56	IN UINT8 BiosInt,\r
	57	IN EFI_IA32_REGISTER_SET *Regs\r
	58	)\r
	59	{\r
26a74a36	60	UINT32 *VectorBase;\r
26a74a36	61	\r
bcecde14	62	Regs->X.Flags.Reserved1 = 1;\r
	63	Regs->X.Flags.Reserved2 = 0;\r
	64	Regs->X.Flags.Reserved3 = 0;\r
	65	Regs->X.Flags.Reserved4 = 0;\r
	66	Regs->X.Flags.IOPL = 3;\r
	67	Regs->X.Flags.NT = 0;\r
	68	Regs->X.Flags.IF = 0;\r
	69	Regs->X.Flags.TF = 0;\r
	70	Regs->X.Flags.CF = 0;\r
26a74a36	71	//\r
	72	// The base address of legacy interrupt vector table is 0.\r
	73	// We use this base address to get the legacy interrupt handler.\r
	74	//\r
	75	VectorBase = 0;\r
	76	\r
bcecde14	77	return InternalLegacyBiosFarCall (\r
bcecde14	78	This,\r
26a74a36	79	(UINT16) ((VectorBase)[BiosInt] >> 16),\r
26a74a36	80	(UINT16) (VectorBase)[BiosInt],\r
bcecde14	81	Regs,\r
	82	&Regs->X.Flags,\r
	83	sizeof (Regs->X.Flags)\r
	84	);\r
	85	}\r
	86	\r
	87	/**\r
	88	Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the\r
	89	16-bit register context on entry and exit. Arguments can be passed on\r
	90	the Stack argument\r
	91	\r
	92	@param This Protocol instance pointer.\r
	93	@param Segment Segemnt of 16-bit mode call\r
	94	@param Offset Offset of 16-bit mdoe call\r
	95	@param Regs Register contexted passed into (and returned) from\r
	96	thunk to 16-bit mode\r
	97	@param Stack Caller allocated stack used to pass arguments\r
	98	@param StackSize Size of Stack in bytes\r
	99	\r
	100	@retval FALSE Thunk completed, and there were no BIOS errors in\r
	101	the target code. See Regs for status.\r
	102	@retval TRUE There was a BIOS erro in the target code.\r
	103	\r
	104	**/\r
	105	BOOLEAN\r
	106	EFIAPI\r
	107	LegacyBiosFarCall86 (\r
	108	IN EFI_LEGACY_BIOS_PROTOCOL *This,\r
	109	IN UINT16 Segment,\r
	110	IN UINT16 Offset,\r
	111	IN EFI_IA32_REGISTER_SET *Regs,\r
	112	IN VOID *Stack,\r
	113	IN UINTN StackSize\r
	114	)\r
	115	{\r
	116	Regs->X.Flags.Reserved1 = 1;\r
	117	Regs->X.Flags.Reserved2 = 0;\r
	118	Regs->X.Flags.Reserved3 = 0;\r
	119	Regs->X.Flags.Reserved4 = 0;\r
	120	Regs->X.Flags.IOPL = 3;\r
	121	Regs->X.Flags.NT = 0;\r
	122	Regs->X.Flags.IF = 1;\r
	123	Regs->X.Flags.TF = 0;\r
	124	Regs->X.Flags.CF = 0;\r
	125	\r
	126	return InternalLegacyBiosFarCall (This, Segment, Offset, Regs, Stack, StackSize);\r
	127	}\r
	128	\r
f767f990	129	/**\r
	130	Provide NULL interrupt handler which is used to check \r
	131	if there is more than one HW interrupt registers with the CPU AP.\r
	132	\r
	133	@param InterruptType - The type of interrupt that occured\r
	134	@param SystemContext - A pointer to the system context when the interrupt occured\r
	135	\r
	136	**/\r
	137	VOID\r
	138	EFIAPI\r
	139	LegacyBiosNullInterruptHandler (\r
	140	IN EFI_EXCEPTION_TYPE InterruptType,\r
	141	IN EFI_SYSTEM_CONTEXT SystemContext\r
	142	)\r
	143	{\r
	144	}\r
	145	\r
bcecde14	146	/**\r
	147	Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the\r
	148	16-bit register context on entry and exit. Arguments can be passed on\r
	149	the Stack argument\r
	150	\r
	151	@param This Protocol instance pointer.\r
	152	@param Segment Segemnt of 16-bit mode call\r
	153	@param Offset Offset of 16-bit mdoe call\r
	154	@param Regs Register contexted passed into (and returned) from thunk to\r
	155	16-bit mode\r
	156	@param Stack Caller allocated stack used to pass arguments\r
	157	@param StackSize Size of Stack in bytes\r
	158	\r
	159	@retval FALSE Thunk completed, and there were no BIOS errors in the target code.\r
	160	See Regs for status.\r
	161	@retval TRUE There was a BIOS erro in the target code.\r
	162	\r
	163	**/\r
	164	BOOLEAN\r
	165	EFIAPI\r
	166	InternalLegacyBiosFarCall (\r
	167	IN EFI_LEGACY_BIOS_PROTOCOL *This,\r
	168	IN UINT16 Segment,\r
	169	IN UINT16 Offset,\r
	170	IN EFI_IA32_REGISTER_SET *Regs,\r
	171	IN VOID *Stack,\r
	172	IN UINTN StackSize\r
	173	)\r
	174	{\r
	175	UINTN Status;\r
	176	LEGACY_BIOS_INSTANCE *Private;\r
	177	UINT16 *Stack16;\r
	178	EFI_TPL OriginalTpl;\r
	179	IA32_REGISTER_SET ThunkRegSet;\r
	180	BOOLEAN InterruptState;\r
f767f990	181	UINT64 TimerPeriod;\r
bcecde14	182	\r
	183	Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);\r
	184	\r
	185	ZeroMem (&ThunkRegSet, sizeof (ThunkRegSet));\r
	186	ThunkRegSet.X.DI = Regs->X.DI;\r
	187	ThunkRegSet.X.SI = Regs->X.SI;\r
	188	ThunkRegSet.X.BP = Regs->X.BP;\r
	189	ThunkRegSet.X.BX = Regs->X.BX;\r
	190	ThunkRegSet.X.DX = Regs->X.DX;\r
	191	//\r
	192	// Sometimes, ECX is used to pass in 32 bit data. For example, INT 1Ah, AX = B10Dh is\r
	193	// "PCI BIOS v2.0c + Write Configuration DWORD" and ECX has the dword to write.\r
	194	//\r
	195	ThunkRegSet.E.ECX = Regs->E.ECX;\r
	196	ThunkRegSet.X.AX = Regs->X.AX;\r
	197	ThunkRegSet.E.DS = Regs->X.DS;\r
	198	ThunkRegSet.E.ES = Regs->X.ES;\r
	199	\r
	200	CopyMem (&(ThunkRegSet.E.EFLAGS.UintN), &(Regs->X.Flags), sizeof (Regs->X.Flags));\r
	201	\r
	202	//\r
	203	// Clear the error flag; thunk code may set it. Stack16 should be the high address\r
	204	// Make Statk16 address the low 16 bit must be not zero.\r
	205	//\r
	206	Stack16 = (UINT16 )((UINT8 ) mThunkContext.RealModeBuffer + mThunkContext.RealModeBufferSize - sizeof (UINT16));\r
	207	\r
	208	//\r
f767f990	209	// Save current rate of DXE Timer\r
	210	//\r
	211	Private->Timer->GetTimerPeriod (Private->Timer, &TimerPeriod);\r
	212	\r
	213	//\r
	214	// Disable DXE Timer while executing in real mode\r
	215	//\r
	216	Private->Timer->SetTimerPeriod (Private->Timer, 0);\r
	217	\r
	218	//\r
	219	// Save and disable interrupt of debug timer\r
bcecde14	220	//\r
	221	InterruptState = SaveAndSetDebugTimerInterrupt (FALSE);\r
	222	\r
	223	//\r
	224	// The call to Legacy16 is a critical section to EFI\r
	225	//\r
	226	OriginalTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
	227	\r
f767f990	228	//\r
	229	// Check to see if there is more than one HW interrupt registers with the CPU AP.\r
	230	// If there is, then ASSERT() since that is not compatible with the CSM because \r
	231	// interupts other than the Timer interrupt that was disabled above can not be \r
	232	// handled properly from real mode.\r
	233	//\r
	234	DEBUG_CODE (\r
	235	UINTN Vector;\r
	236	UINTN Count;\r
	237	\r
	238	for (Vector = 0x20, Count = 0; Vector < 0x100; Vector++) {\r
	239	Status = Private->Cpu->RegisterInterruptHandler (Private->Cpu, Vector, LegacyBiosNullInterruptHandler);\r
	240	if (Status == EFI_ALREADY_STARTED) {\r
	241	Count++;\r
	242	}\r
	243	if (Status == EFI_SUCCESS) {\r
	244	Private->Cpu->RegisterInterruptHandler (Private->Cpu, Vector, NULL);\r
	245	}\r
	246	}\r
	247	if (Count >= 2) {\r
	248	DEBUG ((EFI_D_ERROR, "ERROR: More than one HW interrupt active with CSM enabled\n"));\r
	249	}\r
	250	ASSERT (Count < 2);\r
	251	);\r
	252	\r
	253	//\r
	254	// If the Timer AP has enabled the 8254 timer IRQ and the current 8254 timer \r
	255	// period is less than the CSM required rate of 54.9254, then force the 8254 \r
	256	// PIT counter to 0, which is the CSM required rate of 54.9254 ms\r
	257	//\r
	258	if (Private->TimerUses8254 && TimerPeriod < 549254) {\r
	259	SetPitCount (0);\r
	260	}\r
	261	\r
bcecde14	262	if (Stack != NULL && StackSize != 0) {\r
	263	//\r
	264	// Copy Stack to low memory stack\r
	265	//\r
	266	Stack16 -= StackSize / sizeof (UINT16);\r
	267	CopyMem (Stack16, Stack, StackSize);\r
	268	}\r
	269	\r
	270	ThunkRegSet.E.SS = (UINT16) (((UINTN) Stack16 >> 16) << 12);\r
	271	ThunkRegSet.E.ESP = (UINT16) (UINTN) Stack16;\r
	272	ThunkRegSet.E.CS = Segment;\r
	273	ThunkRegSet.E.Eip = Offset;\r
	274	\r
	275	mThunkContext.RealModeState = &ThunkRegSet;\r
	276	\r
	277	//\r
	278	// Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.\r
	279	//\r
	280	Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259LegacyMode, NULL, NULL);\r
	281	ASSERT_EFI_ERROR (Status);\r
	282	\r
	283	AsmThunk16 (&mThunkContext);\r
	284	\r
	285	//\r
	286	// OPROM may allocate EBDA range by itself and change EBDA base and EBDA size.\r
	287	// Get the current EBDA base address, and compared with pre-allocate minimum\r
	288	// EBDA base address, if the current EBDA base address is smaller, it indicates\r
	289	// PcdEbdaReservedMemorySize should be adjusted to larger for more OPROMs.\r
	290	//\r
	291	DEBUG_CODE (\r
	292	{\r
	293	UINTN EbdaBaseAddress;\r
	294	UINTN ReservedEbdaBaseAddress;\r
	295	\r
	296	EbdaBaseAddress = ((UINT16 ) (UINTN) 0x40E) << 4;\r
	297	ReservedEbdaBaseAddress = CONVENTIONAL_MEMORY_TOP - PcdGet32 (PcdEbdaReservedMemorySize);\r
	298	ASSERT (ReservedEbdaBaseAddress <= EbdaBaseAddress);\r
	299	}\r
	300	);\r
	301	\r
	302	if (Stack != NULL && StackSize != 0) {\r
	303	//\r
	304	// Copy low memory stack to Stack\r
	305	//\r
	306	CopyMem (Stack, Stack16, StackSize);\r
	307	}\r
	308	\r
	309	//\r
	310	// Restore protected mode interrupt state\r
	311	//\r
	312	Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259ProtectedMode, NULL, NULL);\r
	313	ASSERT_EFI_ERROR (Status);\r
	314	\r
	315	mThunkContext.RealModeState = NULL;\r
	316	\r
	317	//\r
b17f22f5	318	// Enable and restore rate of DXE Timer\r
bcecde14	319	//\r
b17f22f5	320	Private->Timer->SetTimerPeriod (Private->Timer, TimerPeriod);\r
bcecde14	321	\r
bcecde14	322	//\r
b17f22f5	323	// End critical section\r
f767f990	324	//\r
b17f22f5	325	gBS->RestoreTPL (OriginalTpl);\r
f767f990	326	\r
	327	//\r
	328	// Restore interrupt of debug timer\r
bcecde14	329	//\r
	330	SaveAndSetDebugTimerInterrupt (InterruptState);\r
	331	\r
	332	Regs->E.EDI = ThunkRegSet.E.EDI;\r
	333	Regs->E.ESI = ThunkRegSet.E.ESI;\r
	334	Regs->E.EBP = ThunkRegSet.E.EBP;\r
	335	Regs->E.EBX = ThunkRegSet.E.EBX;\r
	336	Regs->E.EDX = ThunkRegSet.E.EDX;\r
	337	Regs->E.ECX = ThunkRegSet.E.ECX;\r
	338	Regs->E.EAX = ThunkRegSet.E.EAX;\r
	339	Regs->X.SS = ThunkRegSet.E.SS;\r
	340	Regs->X.CS = ThunkRegSet.E.CS;\r
	341	Regs->X.DS = ThunkRegSet.E.DS;\r
	342	Regs->X.ES = ThunkRegSet.E.ES;\r
	343	\r
	344	CopyMem (&(Regs->X.Flags), &(ThunkRegSet.E.EFLAGS.UintN), sizeof (Regs->X.Flags));\r
	345	\r
	346	return (BOOLEAN) (Regs->X.Flags.CF == 1);\r
	347	}\r
	348	\r
	349	/**\r
	350	Allocate memory < 1 MB and copy the thunker code into low memory. Se up\r
	351	all the descriptors.\r
	352	\r
	353	@param Private Private context for Legacy BIOS\r
	354	\r
	355	@retval EFI_SUCCESS Should only pass.\r
	356	\r
	357	**/\r
	358	EFI_STATUS\r
	359	LegacyBiosInitializeThunk (\r
	360	IN LEGACY_BIOS_INSTANCE *Private\r
	361	)\r
	362	{\r
f767f990	363	EFI_STATUS Status;\r
bcecde14	364	EFI_PHYSICAL_ADDRESS MemoryAddress;\r
f767f990	365	UINT8 TimerVector;\r
bcecde14	366	\r
	367	MemoryAddress = (EFI_PHYSICAL_ADDRESS) (UINTN) Private->IntThunk;\r
	368	\r
	369	mThunkContext.RealModeBuffer = (VOID ) (UINTN) (MemoryAddress + ((sizeof (LOW_MEMORY_THUNK) / EFI_PAGE_SIZE) + 1) EFI_PAGE_SIZE);\r
	370	mThunkContext.RealModeBufferSize = EFI_PAGE_SIZE;\r
	371	mThunkContext.ThunkAttributes = THUNK_ATTRIBUTE_BIG_REAL_MODE \| THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15;\r
	372	\r
	373	AsmPrepareThunk16 (&mThunkContext);\r
	374	\r
f767f990	375	//\r
	376	// Get the interrupt vector number corresponding to IRQ0 from the 8259 driver\r
	377	//\r
	378	TimerVector = 0;\r
	379	Status = Private->Legacy8259->GetVector (Private->Legacy8259, Efi8259Irq0, &TimerVector);\r
	380	ASSERT_EFI_ERROR (Status);\r
	381	\r
	382	//\r
	383	// Check to see if the Timer AP has hooked the IRQ0 from the 8254 PIT\r
	384	// \r
	385	Status = Private->Cpu->RegisterInterruptHandler (\r
	386	Private->Cpu, \r
	387	TimerVector, \r
	388	LegacyBiosNullInterruptHandler\r
	389	);\r
	390	if (Status == EFI_SUCCESS) {\r
	391	//\r
	392	// If the Timer AP has not enabled the 8254 timer IRQ, then force the 8254 PIT \r
	393	// counter to 0, which is the CSM required rate of 54.9254 ms\r
	394	//\r
	395	Private->Cpu->RegisterInterruptHandler (\r
	396	Private->Cpu, \r
	397	TimerVector, \r
	398	NULL\r
	399	);\r
	400	SetPitCount (0);\r
	401	\r
	402	//\r
	403	// Save status that the Timer AP is not using the 8254 PIT\r
	404	//\r
	405	Private->TimerUses8254 = FALSE;\r
	406	} else if (Status == EFI_ALREADY_STARTED) {\r
	407	//\r
	408	// Save status that the Timer AP is using the 8254 PIT\r
	409	//\r
	410	Private->TimerUses8254 = TRUE;\r
	411	} else {\r
	412	//\r
	413	// Unexpected status from CPU AP RegisterInterruptHandler()\r
	414	//\r
	415	ASSERT (FALSE);\r
	416	}\r
	417	\r
bcecde14	418	return EFI_SUCCESS;\r
bcecde14	419	}\r