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From: "Ni, Ray" <ray.ni@intel.com>
To: "Liu, Zhiguang" <zhiguang.liu@intel.com>,
	"devel@edk2.groups.io" <devel@edk2.groups.io>
Cc: "Dong, Eric" <eric.dong@intel.com>,
	"Kumar, Rahul R" <rahul.r.kumar@intel.com>,
	Leif Lindholm <quic_llindhol@quicinc.com>,
	"Bi, Dandan" <dandan.bi@intel.com>,
	"Gao, Liming" <gaoliming@byosoft.com.cn>,
	"Wang, Jian J" <jian.j.wang@intel.com>,
	Ard Biesheuvel <ardb+tianocore@kernel.org>,
	Sami Mujawar <sami.mujawar@arm.com>
Subject: Re: [PATCH 1/2] UefiCpuPkg: Simplify InitializeSeparateExceptionStacks
Date: Thu, 4 Aug 2022 05:37:19 +0000	[thread overview]
Message-ID: <MWHPR11MB1631F6055FB20C51FB11FB4F8C9F9@MWHPR11MB1631.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20220722075737.897-2-zhiguang.liu@intel.com>

1. Old code contains a picture that describes the buffer layout. It seems the picture disappears in new code.
2. When TSS is enabled, there is one descriptor in GDT that points to the TSS. But TSS is not part of GDT. New code contains comments to treat TSS as part of GDT.
3. Did you run ECC and uncrustify? I saw some coding style issues.
4. Assertion in below code is unnecessary.
    if (BufferSize == 0 ) {
      continue;
    }
    ASSERT (BufferSize != 0);

5. EDKII coding style doesn't allow single line code comments just after the code.
6. Is it possible to simplify the ESS_DATA structure further? For example, are IdtTable/IdtTableSize needed in the structure? Please evaluate further and simplify that in a separate patch.
7. "SWITCH_STACK_DATA" semes to support the stack switch. Can we use "EXCEPTION_STACK_SWITCH_CONTEXT"? "EXCEPTION_" is used here to indicate it's not for stack switch immediately but for exception handlers.
8. Is it possible to run the AP procedure in parallel instead of one-by-one? Such optimization can be done in a separate patch.

Thanks,
Ray

> -----Original Message-----
> From: Liu, Zhiguang <zhiguang.liu@intel.com>
> Sent: Friday, July 22, 2022 3:58 PM
> To: devel@edk2.groups.io
> Cc: Liu, Zhiguang <zhiguang.liu@intel.com>; Dong, Eric
> <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Kumar, Rahul1
> <rahul1.kumar@intel.com>; Leif Lindholm <quic_llindhol@quicinc.com>; Bi,
> Dandan <dandan.bi@intel.com>; Gao, Liming <gaoliming@byosoft.com.cn>;
> Wang, Jian J <jian.j.wang@intel.com>; Ard Biesheuvel
> <ardb+tianocore@kernel.org>; Sami Mujawar <sami.mujawar@arm.com>
> Subject: [PATCH 1/2] UefiCpuPkg: Simplify InitializeSeparateExceptionStacks
> 
> Hide the Exception implementation details in CpuExcetionHandlerLib and
> caller only need to provide buffer
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> Cc: Leif Lindholm <quic_llindhol@quicinc.com>
> Cc: Dandan Bi <dandan.bi@intel.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> Cc: Sami Mujawar <sami.mujawar@arm.com>
> Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
> ---
>  .../Library/ArmExceptionLib/ArmExceptionLib.c |  15 +-
>  MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c       |   4 +-
>  .../Include/Library/CpuExceptionHandlerLib.h  |  15 +-
>  .../CpuExceptionHandlerLibNull.c              |  15 +-
>  UefiCpuPkg/CpuDxe/CpuMp.c                     | 157 +++-------------
>  UefiCpuPkg/CpuDxe/CpuMp.h                     |  10 +-
>  UefiCpuPkg/CpuMpPei/CpuMpPei.c                | 174 ++++--------------
>  UefiCpuPkg/CpuMpPei/CpuMpPei.h                |  10 +-
>  .../CpuExceptionHandlerLib/DxeException.c     |  77 +++++---
>  .../Ia32/ArchExceptionHandler.c               |   3 +-
>  .../CpuExceptionHandlerLib/PeiCpuException.c  |  62 ++++++-
>  .../PeiCpuExceptionHandlerLib.inf             |   4 +-
>  .../SecPeiCpuException.c                      |  15 +-
>  .../CpuExceptionHandlerLib/SmmException.c     |  15 +-
>  .../X64/ArchExceptionHandler.c                |   3 +-
>  15 files changed, 231 insertions(+), 348 deletions(-)
> 
> diff --git a/ArmPkg/Library/ArmExceptionLib/ArmExceptionLib.c
> b/ArmPkg/Library/ArmExceptionLib/ArmExceptionLib.c
> index 2c7bc66aa7..a521c33f32 100644
> --- a/ArmPkg/Library/ArmExceptionLib/ArmExceptionLib.c
> +++ b/ArmPkg/Library/ArmExceptionLib/ArmExceptionLib.c
> @@ -288,20 +288,23 @@ CommonCExceptionHandler (
> 
>  /**
>    Setup separate stacks for certain exception handlers.
> +  If the input Buffer and BufferSize are both NULL, use global variable if
> possible.
> 
> -  InitData is optional and processor arch dependent.
> -
> -  @param[in]  InitData      Pointer to data optional for information about how
> -                            to assign stacks for certain exception handlers.
> +  @param[in]       Buffer        Point to buffer used to separate exception stack.
> +  @param[in, out]  BufferSize    On input, it indicates the byte size of Buffer.
> +                                 If the size is not enough, the return status will
> +                                 be EFI_BUFFER_TOO_SMALL, and output BufferSize
> +                                 will be the size it needs.
> 
>    @retval EFI_SUCCESS             The stacks are assigned successfully.
>    @retval EFI_UNSUPPORTED         This function is not supported.
> -
> +  @retval EFI_BUFFER_TOO_SMALL    This BufferSize is too small.
>  **/
>  EFI_STATUS
>  EFIAPI
>  InitializeSeparateExceptionStacks (
> -  IN CPU_EXCEPTION_INIT_DATA  *InitData OPTIONAL
> +  IN     VOID   *Buffer,
> +  IN OUT UINTN  *BufferSize
>    )
>  {
>    return EFI_SUCCESS;
> diff --git a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
> b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
> index 0a1f3d79e2..5733f0c8ec 100644
> --- a/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
> +++ b/MdeModulePkg/Core/Dxe/DxeMain/DxeMain.c
> @@ -1,7 +1,7 @@
>  /** @file
>    DXE Core Main Entry Point
> 
> -Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
> +Copyright (c) 2006 - 2022, Intel Corporation. All rights reserved.<BR>
>  SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  **/
> @@ -260,7 +260,7 @@ DxeMain (
>    // Setup Stack Guard
>    //
>    if (PcdGetBool (PcdCpuStackGuard)) {
> -    Status = InitializeSeparateExceptionStacks (NULL);
> +    Status = InitializeSeparateExceptionStacks (NULL, NULL);
>      ASSERT_EFI_ERROR (Status);
>    }
> 
> diff --git a/MdeModulePkg/Include/Library/CpuExceptionHandlerLib.h
> b/MdeModulePkg/Include/Library/CpuExceptionHandlerLib.h
> index 9a495081f7..8d44ed916a 100644
> --- a/MdeModulePkg/Include/Library/CpuExceptionHandlerLib.h
> +++ b/MdeModulePkg/Include/Library/CpuExceptionHandlerLib.h
> @@ -104,20 +104,23 @@ InitializeCpuExceptionHandlers (
> 
>  /**
>    Setup separate stacks for certain exception handlers.
> +  If the input Buffer and BufferSize are both NULL, use global variable if
> possible.
> 
> -  InitData is optional and processor arch dependent.
> -
> -  @param[in]  InitData      Pointer to data optional for information about how
> -                            to assign stacks for certain exception handlers.
> +  @param[in]       Buffer        Point to buffer used to separate exception stack.
> +  @param[in, out]  BufferSize    On input, it indicates the byte size of Buffer.
> +                                 If the size is not enough, the return status will
> +                                 be EFI_BUFFER_TOO_SMALL, and output BufferSize
> +                                 will be the size it needs.
> 
>    @retval EFI_SUCCESS             The stacks are assigned successfully.
>    @retval EFI_UNSUPPORTED         This function is not supported.
> -
> +  @retval EFI_BUFFER_TOO_SMALL    This BufferSize is too small.
>  **/
>  EFI_STATUS
>  EFIAPI
>  InitializeSeparateExceptionStacks (
> -  IN CPU_EXCEPTION_INIT_DATA  *InitData OPTIONAL
> +  IN     VOID   *Buffer,
> +  IN OUT UINTN  *BufferSize
>    );
> 
>  /**
> diff --git
> a/MdeModulePkg/Library/CpuExceptionHandlerLibNull/CpuExceptionHandl
> erLibNull.c
> b/MdeModulePkg/Library/CpuExceptionHandlerLibNull/CpuExceptionHandl
> erLibNull.c
> index 8aeedcb4d1..74908a379b 100644
> ---
> a/MdeModulePkg/Library/CpuExceptionHandlerLibNull/CpuExceptionHandl
> erLibNull.c
> +++
> b/MdeModulePkg/Library/CpuExceptionHandlerLibNull/CpuExceptionHandl
> erLibNull.c
> @@ -83,20 +83,23 @@ DumpCpuContext (
> 
>  /**
>    Setup separate stacks for certain exception handlers.
> +  If the input Buffer and BufferSize are both NULL, use global variable if
> possible.
> 
> -  InitData is optional and processor arch dependent.
> -
> -  @param[in]  InitData      Pointer to data optional for information about how
> -                            to assign stacks for certain exception handlers.
> +  @param[in]       Buffer        Point to buffer used to separate exception stack.
> +  @param[in, out]  BufferSize    On input, it indicates the byte size of Buffer.
> +                                 If the size is not enough, the return status will
> +                                 be EFI_BUFFER_TOO_SMALL, and output BufferSize
> +                                 will be the size it needs.
> 
>    @retval EFI_SUCCESS             The stacks are assigned successfully.
>    @retval EFI_UNSUPPORTED         This function is not supported.
> -
> +  @retval EFI_BUFFER_TOO_SMALL    This BufferSize is too small.
>  **/
>  EFI_STATUS
>  EFIAPI
>  InitializeSeparateExceptionStacks (
> -  IN CPU_EXCEPTION_INIT_DATA  *InitData OPTIONAL
> +  IN     VOID   *Buffer,
> +  IN OUT UINTN  *BufferSize
>    )
>  {
>    return EFI_UNSUPPORTED;
> diff --git a/UefiCpuPkg/CpuDxe/CpuMp.c b/UefiCpuPkg/CpuDxe/CpuMp.c
> index e385f585c7..286ef2d3fd 100644
> --- a/UefiCpuPkg/CpuDxe/CpuMp.c
> +++ b/UefiCpuPkg/CpuDxe/CpuMp.c
> @@ -596,24 +596,6 @@ CollectBistDataFromHob (
>    }
>  }
> 
> -/**
> -  Get GDT register value.
> -
> -  This function is mainly for AP purpose because AP may have different GDT
> -  table than BSP.
> -
> -  @param[in,out] Buffer  The pointer to private data buffer.
> -
> -**/
> -VOID
> -EFIAPI
> -GetGdtr (
> -  IN OUT VOID  *Buffer
> -  )
> -{
> -  AsmReadGdtr ((IA32_DESCRIPTOR *)Buffer);
> -}
> -
>  /**
>    Initializes CPU exceptions handlers for the sake of stack switch requirement.
> 
> @@ -629,27 +611,17 @@ InitializeExceptionStackSwitchHandlers (
>    IN OUT VOID  *Buffer
>    )
>  {
> -  CPU_EXCEPTION_INIT_DATA  *EssData;
> -  IA32_DESCRIPTOR          Idtr;
> -  EFI_STATUS               Status;
> +  SWITCH_STACK_DATA  *SwitchStackData;
> 
> -  EssData = Buffer;
> -  //
> -  // We don't plan to replace IDT table with a new one, but we should not
> assume
> -  // the AP's IDT is the same as BSP's IDT either.
> -  //
> -  AsmReadIdtr (&Idtr);
> -  EssData->Ia32.IdtTable     = (VOID *)Idtr.Base;
> -  EssData->Ia32.IdtTableSize = Idtr.Limit + 1;
> -  Status                     = InitializeSeparateExceptionStacks (EssData);
> -  ASSERT_EFI_ERROR (Status);
> +  SwitchStackData = (SWITCH_STACK_DATA *)Buffer;
> +  InitializeSeparateExceptionStacks (SwitchStackData->Buffer,
> SwitchStackData->BufferSize);
>  }
> 
>  /**
>    Initializes MP exceptions handlers for the sake of stack switch requirement.
> 
>    This function will allocate required resources required to setup stack switch
> -  and pass them through CPU_EXCEPTION_INIT_DATA to each logic
> processor.
> +  and pass them through SwitchStackData to each logic processor.
> 
>  **/
>  VOID
> @@ -657,129 +629,52 @@ InitializeMpExceptionStackSwitchHandlers (
>    VOID
>    )
>  {
> -  UINTN                    Index;
> -  UINTN                    Bsp;
> -  UINTN                    ExceptionNumber;
> -  UINTN                    OldGdtSize;
> -  UINTN                    NewGdtSize;
> -  UINTN                    NewStackSize;
> -  IA32_DESCRIPTOR          Gdtr;
> -  CPU_EXCEPTION_INIT_DATA  EssData;
> -  UINT8                    *GdtBuffer;
> -  UINT8                    *StackTop;
> -
> -  ExceptionNumber = FixedPcdGetSize (PcdCpuStackSwitchExceptionList);
> -  NewStackSize    = FixedPcdGet32 (PcdCpuKnownGoodStackSize) *
> ExceptionNumber;
> -
> -  StackTop = AllocateRuntimeZeroPool (NewStackSize *
> mNumberOfProcessors);
> -  ASSERT (StackTop != NULL);
> -  StackTop += NewStackSize  * mNumberOfProcessors;
> +  UINTN              Index;
> +  UINTN              Bsp;
> +  UINT8              *Buffer;
> +  SWITCH_STACK_DATA  SwitchStackData;
> +  UINTN              BufferSize;
> 
> -  //
> -  // The default exception handlers must have been initialized. Let's just skip
> -  // it in this method.
> -  //
> -  EssData.Ia32.Revision            = CPU_EXCEPTION_INIT_DATA_REV;
> -  EssData.Ia32.InitDefaultHandlers = FALSE;
> -
> -  EssData.Ia32.StackSwitchExceptions      = FixedPcdGetPtr
> (PcdCpuStackSwitchExceptionList);
> -  EssData.Ia32.StackSwitchExceptionNumber = ExceptionNumber;
> -  EssData.Ia32.KnownGoodStackSize         = FixedPcdGet32
> (PcdCpuKnownGoodStackSize);
> -
> -  //
> -  // Initialize Gdtr to suppress incorrect compiler/analyzer warnings.
> -  //
> -  Gdtr.Base  = 0;
> -  Gdtr.Limit = 0;
> +  SwitchStackData.BufferSize = &BufferSize;
>    MpInitLibWhoAmI (&Bsp);
> +
>    for (Index = 0; Index < mNumberOfProcessors; ++Index) {
> -    //
> -    // To support stack switch, we need to re-construct GDT but not IDT.
> -    //
> +    SwitchStackData.Buffer = NULL;
> +    BufferSize             = 0;
> +
>      if (Index == Bsp) {
> -      GetGdtr (&Gdtr);
> +      InitializeExceptionStackSwitchHandlers (&SwitchStackData);
>      } else {
>        //
> -      // AP might have different size of GDT from BSP.
> +      // AP might need different buffer size from BSP.
>        //
> -      MpInitLibStartupThisAP (GetGdtr, Index, NULL, 0, (VOID *)&Gdtr, NULL);
> +      MpInitLibStartupThisAP (InitializeExceptionStackSwitchHandlers, Index,
> NULL, 0, (VOID *)&SwitchStackData, NULL);
>      }
> 
> -    //
> -    // X64 needs only one TSS of current task working for all exceptions
> -    // because of its IST feature. IA32 needs one TSS for each exception
> -    // in addition to current task. Since AP is not supposed to allocate
> -    // memory, we have to do it in BSP. To simplify the code, we allocate
> -    // memory for IA32 case to cover both IA32 and X64 exception stack
> -    // switch.
> -    //
> -    // Layout of memory to allocate for each processor:
> -    //    --------------------------------
> -    //    |            Alignment         |  (just in case)
> -    //    --------------------------------
> -    //    |                              |
> -    //    |        Original GDT          |
> -    //    |                              |
> -    //    --------------------------------
> -    //    |    Current task descriptor   |
> -    //    --------------------------------
> -    //    |                              |
> -    //    |  Exception task descriptors  |  X ExceptionNumber
> -    //    |                              |
> -    //    --------------------------------
> -    //    |  Current task-state segment  |
> -    //    --------------------------------
> -    //    |                              |
> -    //    | Exception task-state segment |  X ExceptionNumber
> -    //    |                              |
> -    //    --------------------------------
> -    //
> -    OldGdtSize                        = Gdtr.Limit + 1;
> -    EssData.Ia32.ExceptionTssDescSize = sizeof (IA32_TSS_DESCRIPTOR) *
> -                                        (ExceptionNumber + 1);
> -    EssData.Ia32.ExceptionTssSize = sizeof (IA32_TASK_STATE_SEGMENT) *
> -                                    (ExceptionNumber + 1);
> -    NewGdtSize = sizeof (IA32_TSS_DESCRIPTOR) +
> -                 OldGdtSize +
> -                 EssData.Ia32.ExceptionTssDescSize +
> -                 EssData.Ia32.ExceptionTssSize;
> -
> -    GdtBuffer = AllocateRuntimeZeroPool (NewGdtSize);
> -    ASSERT (GdtBuffer != NULL);
> -
> -    //
> -    // Make sure GDT table alignment
> -    //
> -    EssData.Ia32.GdtTable     = ALIGN_POINTER (GdtBuffer, sizeof
> (IA32_TSS_DESCRIPTOR));
> -    NewGdtSize               -= ((UINT8 *)EssData.Ia32.GdtTable - GdtBuffer);
> -    EssData.Ia32.GdtTableSize = NewGdtSize;
> -
> -    EssData.Ia32.ExceptionTssDesc = ((UINT8 *)EssData.Ia32.GdtTable +
> OldGdtSize);
> -    EssData.Ia32.ExceptionTss     = ((UINT8 *)EssData.Ia32.GdtTable +
> OldGdtSize +
> -                                     EssData.Ia32.ExceptionTssDescSize);
> -
> -    EssData.Ia32.KnownGoodStackTop = (UINTN)StackTop;
> +    ASSERT (BufferSize != 0);
> +    Buffer = AllocateRuntimeZeroPool (BufferSize);
> +    ASSERT (Buffer != NULL);
> +    SwitchStackData.Buffer = Buffer;
>      DEBUG ((
>        DEBUG_INFO,
> -      "Exception stack top[cpu%lu]: 0x%lX\n",
> +      "Buffer[cpu%lu] for InitializeExceptionStackSwitchHandlers: 0x%lX with
> size 0x%x\n",
>        (UINT64)(UINTN)Index,
> -      (UINT64)(UINTN)StackTop
> +      (UINT64)(UINTN)Buffer,
> +      (UINT32)BufferSize
>        ));
> 
>      if (Index == Bsp) {
> -      InitializeExceptionStackSwitchHandlers (&EssData);
> +      InitializeExceptionStackSwitchHandlers (&SwitchStackData);
>      } else {
>        MpInitLibStartupThisAP (
>          InitializeExceptionStackSwitchHandlers,
>          Index,
>          NULL,
>          0,
> -        (VOID *)&EssData,
> +        (VOID *)&SwitchStackData,
>          NULL
>          );
>      }
> -
> -    StackTop -= NewStackSize;
>    }
>  }
> 
> diff --git a/UefiCpuPkg/CpuDxe/CpuMp.h b/UefiCpuPkg/CpuDxe/CpuMp.h
> index b461753510..c545a711b8 100644
> --- a/UefiCpuPkg/CpuDxe/CpuMp.h
> +++ b/UefiCpuPkg/CpuDxe/CpuMp.h
> @@ -1,7 +1,7 @@
>  /** @file
>    CPU DXE MP support
> 
> -  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
> +  Copyright (c) 2006 - 2022, Intel Corporation. All rights reserved.<BR>
>    SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  **/
> @@ -9,6 +9,14 @@
>  #ifndef _CPU_MP_H_
>  #define _CPU_MP_H_
> 
> +//
> +// Structure for InitializeSeparateExceptionStacks
> +//
> +typedef struct {
> +  VOID     *Buffer;
> +  UINTN    *BufferSize;
> +} SWITCH_STACK_DATA;
> +
>  /**
>    Initialize Multi-processor support.
> 
> diff --git a/UefiCpuPkg/CpuMpPei/CpuMpPei.c
> b/UefiCpuPkg/CpuMpPei/CpuMpPei.c
> index d4786979fa..dfc0128361 100644
> --- a/UefiCpuPkg/CpuMpPei/CpuMpPei.c
> +++ b/UefiCpuPkg/CpuMpPei/CpuMpPei.c
> @@ -1,7 +1,7 @@
>  /** @file
>    CPU PEI Module installs CPU Multiple Processor PPI.
> 
> -  Copyright (c) 2015 - 2021, Intel Corporation. All rights reserved.<BR>
> +  Copyright (c) 2015 - 2022, Intel Corporation. All rights reserved.<BR>
>    SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  **/
> @@ -411,24 +411,6 @@ PeiWhoAmI (
>    return MpInitLibWhoAmI (ProcessorNumber);
>  }
> 
> -/**
> -  Get GDT register value.
> -
> -  This function is mainly for AP purpose because AP may have different GDT
> -  table than BSP.
> -
> -  @param[in,out] Buffer  The pointer to private data buffer.
> -
> -**/
> -VOID
> -EFIAPI
> -GetGdtr (
> -  IN OUT VOID  *Buffer
> -  )
> -{
> -  AsmReadGdtr ((IA32_DESCRIPTOR *)Buffer);
> -}
> -
>  /**
>    Initializes CPU exceptions handlers for the sake of stack switch requirement.
> 
> @@ -444,27 +426,17 @@ InitializeExceptionStackSwitchHandlers (
>    IN OUT VOID  *Buffer
>    )
>  {
> -  CPU_EXCEPTION_INIT_DATA  *EssData;
> -  IA32_DESCRIPTOR          Idtr;
> -  EFI_STATUS               Status;
> +  SWITCH_STACK_DATA  *SwitchStackData;
> 
> -  EssData = Buffer;
> -  //
> -  // We don't plan to replace IDT table with a new one, but we should not
> assume
> -  // the AP's IDT is the same as BSP's IDT either.
> -  //
> -  AsmReadIdtr (&Idtr);
> -  EssData->Ia32.IdtTable     = (VOID *)Idtr.Base;
> -  EssData->Ia32.IdtTableSize = Idtr.Limit + 1;
> -  Status                     = InitializeSeparateExceptionStacks (EssData);
> -  ASSERT_EFI_ERROR (Status);
> +  SwitchStackData = (SWITCH_STACK_DATA *)Buffer;
> +  InitializeSeparateExceptionStacks (SwitchStackData->Buffer,
> SwitchStackData->BufferSize);
>  }
> 
>  /**
>    Initializes MP exceptions handlers for the sake of stack switch requirement.
> 
>    This function will allocate required resources required to setup stack switch
> -  and pass them through CPU_EXCEPTION_INIT_DATA to each logic
> processor.
> +  and pass them through SwitchStackData to each logic processor.
> 
>  **/
>  VOID
> @@ -472,18 +444,14 @@ InitializeMpExceptionStackSwitchHandlers (
>    VOID
>    )
>  {
> -  EFI_STATUS               Status;
> -  UINTN                    Index;
> -  UINTN                    Bsp;
> -  UINTN                    ExceptionNumber;
> -  UINTN                    OldGdtSize;
> -  UINTN                    NewGdtSize;
> -  UINTN                    NewStackSize;
> -  IA32_DESCRIPTOR          Gdtr;
> -  CPU_EXCEPTION_INIT_DATA  EssData;
> -  UINT8                    *GdtBuffer;
> -  UINT8                    *StackTop;
> -  UINTN                    NumberOfProcessors;
> +  UINTN              Index;
> +  UINTN              Bsp;
> +  UINT8              *Buffer;
> +  SWITCH_STACK_DATA  SwitchStackData;
> +  UINTN              BufferSize;
> +
> +  SwitchStackData.BufferSize = &BufferSize;
> +  UINTN  NumberOfProcessors;
> 
>    if (!PcdGetBool (PcdCpuStackGuard)) {
>      return;
> @@ -492,128 +460,48 @@ InitializeMpExceptionStackSwitchHandlers (
>    MpInitLibGetNumberOfProcessors (&NumberOfProcessors, NULL);
>    MpInitLibWhoAmI (&Bsp);
> 
> -  ExceptionNumber = FixedPcdGetSize (PcdCpuStackSwitchExceptionList);
> -  NewStackSize    = FixedPcdGet32 (PcdCpuKnownGoodStackSize) *
> ExceptionNumber;
> -
> -  StackTop = AllocatePages (EFI_SIZE_TO_PAGES (NewStackSize *
> NumberOfProcessors));
> -  ASSERT (StackTop != NULL);
> -  if (StackTop == NULL) {
> -    return;
> -  }
> -
> -  StackTop += NewStackSize  * NumberOfProcessors;
> -
> -  //
> -  // The default exception handlers must have been initialized. Let's just skip
> -  // it in this method.
> -  //
> -  EssData.Ia32.Revision            = CPU_EXCEPTION_INIT_DATA_REV;
> -  EssData.Ia32.InitDefaultHandlers = FALSE;
> -
> -  EssData.Ia32.StackSwitchExceptions      = FixedPcdGetPtr
> (PcdCpuStackSwitchExceptionList);
> -  EssData.Ia32.StackSwitchExceptionNumber = ExceptionNumber;
> -  EssData.Ia32.KnownGoodStackSize         = FixedPcdGet32
> (PcdCpuKnownGoodStackSize);
> -
> -  //
> -  // Initialize Gdtr to suppress incorrect compiler/analyzer warnings.
> -  //
> -  Gdtr.Base  = 0;
> -  Gdtr.Limit = 0;
>    for (Index = 0; Index < NumberOfProcessors; ++Index) {
> -    //
> -    // To support stack switch, we need to re-construct GDT but not IDT.
> -    //
> +    SwitchStackData.Buffer = NULL;
> +    BufferSize             = 0;
> +
>      if (Index == Bsp) {
> -      GetGdtr (&Gdtr);
> +      InitializeExceptionStackSwitchHandlers (&SwitchStackData);
>      } else {
>        //
> -      // AP might have different size of GDT from BSP.
> +      // AP might need different buffer size from BSP.
>        //
> -      MpInitLibStartupThisAP (GetGdtr, Index, NULL, 0, (VOID *)&Gdtr, NULL);
> +      MpInitLibStartupThisAP (InitializeExceptionStackSwitchHandlers, Index,
> NULL, 0, (VOID *)&SwitchStackData, NULL);
>      }
> 
> -    //
> -    // X64 needs only one TSS of current task working for all exceptions
> -    // because of its IST feature. IA32 needs one TSS for each exception
> -    // in addition to current task. Since AP is not supposed to allocate
> -    // memory, we have to do it in BSP. To simplify the code, we allocate
> -    // memory for IA32 case to cover both IA32 and X64 exception stack
> -    // switch.
> -    //
> -    // Layout of memory to allocate for each processor:
> -    //    --------------------------------
> -    //    |            Alignment         |  (just in case)
> -    //    --------------------------------
> -    //    |                              |
> -    //    |        Original GDT          |
> -    //    |                              |
> -    //    --------------------------------
> -    //    |    Current task descriptor   |
> -    //    --------------------------------
> -    //    |                              |
> -    //    |  Exception task descriptors  |  X ExceptionNumber
> -    //    |                              |
> -    //    --------------------------------
> -    //    |  Current task-state segment  |
> -    //    --------------------------------
> -    //    |                              |
> -    //    | Exception task-state segment |  X ExceptionNumber
> -    //    |                              |
> -    //    --------------------------------
> -    //
> -    OldGdtSize                        = Gdtr.Limit + 1;
> -    EssData.Ia32.ExceptionTssDescSize = sizeof (IA32_TSS_DESCRIPTOR) *
> -                                        (ExceptionNumber + 1);
> -    EssData.Ia32.ExceptionTssSize = sizeof (IA32_TASK_STATE_SEGMENT) *
> -                                    (ExceptionNumber + 1);
> -    NewGdtSize = sizeof (IA32_TSS_DESCRIPTOR) +
> -                 OldGdtSize +
> -                 EssData.Ia32.ExceptionTssDescSize +
> -                 EssData.Ia32.ExceptionTssSize;
> -
> -    Status = PeiServicesAllocatePool (
> -               NewGdtSize,
> -               (VOID **)&GdtBuffer
> -               );
> -    ASSERT (GdtBuffer != NULL);
> -    if (EFI_ERROR (Status)) {
> -      ASSERT_EFI_ERROR (Status);
> -      return;
> +    if (BufferSize == 0 ) {
> +      continue;
>      }
> 
> -    //
> -    // Make sure GDT table alignment
> -    //
> -    EssData.Ia32.GdtTable     = ALIGN_POINTER (GdtBuffer, sizeof
> (IA32_TSS_DESCRIPTOR));
> -    NewGdtSize               -= ((UINT8 *)EssData.Ia32.GdtTable - GdtBuffer);
> -    EssData.Ia32.GdtTableSize = NewGdtSize;
> -
> -    EssData.Ia32.ExceptionTssDesc = ((UINT8 *)EssData.Ia32.GdtTable +
> OldGdtSize);
> -    EssData.Ia32.ExceptionTss     = ((UINT8 *)EssData.Ia32.GdtTable +
> OldGdtSize +
> -                                     EssData.Ia32.ExceptionTssDescSize);
> -
> -    EssData.Ia32.KnownGoodStackTop = (UINTN)StackTop;
> +    ASSERT (BufferSize != 0);
> +    Buffer = AllocatePages (EFI_SIZE_TO_PAGES (BufferSize));
> +    ASSERT (Buffer != NULL);
> +    ZeroMem (Buffer, EFI_PAGES_TO_SIZE (EFI_SIZE_TO_PAGES
> (BufferSize)));
> +    SwitchStackData.Buffer = Buffer;
>      DEBUG ((
>        DEBUG_INFO,
> -      "Exception stack top[cpu%lu]: 0x%lX\n",
> +      "Buffer[cpu%lu] for InitializeExceptionStackSwitchHandlers: 0x%lX with
> size 0x%x\n",
>        (UINT64)(UINTN)Index,
> -      (UINT64)(UINTN)StackTop
> +      (UINT64)(UINTN)Buffer,
> +      (UINT32)BufferSize
>        ));
> 
>      if (Index == Bsp) {
> -      InitializeExceptionStackSwitchHandlers (&EssData);
> +      InitializeExceptionStackSwitchHandlers (&SwitchStackData);
>      } else {
>        MpInitLibStartupThisAP (
>          InitializeExceptionStackSwitchHandlers,
>          Index,
>          NULL,
>          0,
> -        (VOID *)&EssData,
> +        (VOID *)&SwitchStackData,
>          NULL
>          );
>      }
> -
> -    StackTop -= NewStackSize;
>    }
>  }
> 
> diff --git a/UefiCpuPkg/CpuMpPei/CpuMpPei.h
> b/UefiCpuPkg/CpuMpPei/CpuMpPei.h
> index 0649c48d14..f4fe7a3d39 100644
> --- a/UefiCpuPkg/CpuMpPei/CpuMpPei.h
> +++ b/UefiCpuPkg/CpuMpPei/CpuMpPei.h
> @@ -1,7 +1,7 @@
>  /** @file
>    Definitions to install Multiple Processor PPI.
> 
> -  Copyright (c) 2015 - 2021, Intel Corporation. All rights reserved.<BR>
> +  Copyright (c) 2015 - 2022, Intel Corporation. All rights reserved.<BR>
>    SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  **/
> @@ -31,6 +31,14 @@
> 
>  extern EFI_PEI_PPI_DESCRIPTOR  mPeiCpuMpPpiDesc;
> 
> +//
> +// Structure for InitializeSeparateExceptionStacks
> +//
> +typedef struct {
> +  VOID     *Buffer;
> +  UINTN    *BufferSize;
> +} SWITCH_STACK_DATA;
> +
>  /**
>    This service retrieves the number of logical processor in the platform
>    and the number of those logical processors that are enabled on this boot.
> diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeException.c
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeException.c
> index e62bb5e6c0..4b75c42f1e 100644
> --- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeException.c
> +++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeException.c
> @@ -104,48 +104,71 @@ RegisterCpuInterruptHandler (
> 
>  /**
>    Setup separate stacks for certain exception handlers.
> +  If the input Buffer and BufferSize are both NULL, use global variable if
> possible.
> 
> -  InitData is optional and processor arch dependent.
> -
> -  @param[in]  InitData      Pointer to data optional for information about how
> -                            to assign stacks for certain exception handlers.
> +  @param[in]       Buffer        Point to buffer used to separate exception stack.
> +  @param[in, out]  BufferSize    On input, it indicates the byte size of Buffer.
> +                                 If the size is not enough, the return status will
> +                                 be EFI_BUFFER_TOO_SMALL, and output BufferSize
> +                                 will be the size it needs.
> 
>    @retval EFI_SUCCESS             The stacks are assigned successfully.
>    @retval EFI_UNSUPPORTED         This function is not supported.
> -
> +  @retval EFI_BUFFER_TOO_SMALL    This BufferSize is too small.
>  **/
>  EFI_STATUS
>  EFIAPI
>  InitializeSeparateExceptionStacks (
> -  IN CPU_EXCEPTION_INIT_DATA  *InitData OPTIONAL
> +  IN     VOID   *Buffer,
> +  IN OUT UINTN  *BufferSize
>    )
>  {
>    CPU_EXCEPTION_INIT_DATA  EssData;
>    IA32_DESCRIPTOR          Idtr;
>    IA32_DESCRIPTOR          Gdtr;
> +  UINTN                    NeedBufferSize;
> +  UINTN                    StackTop;
> +  UINT8                    *NewGdtTable;
> 
> -  if (InitData == NULL) {
> +  AsmReadGdtr (&Gdtr);
> +  if ((Buffer == NULL) && (BufferSize == NULL)) {
>      SetMem (mNewGdt, sizeof (mNewGdt), 0);
> -
> -    AsmReadIdtr (&Idtr);
> -    AsmReadGdtr (&Gdtr);
> -
> -    EssData.X64.Revision                   = CPU_EXCEPTION_INIT_DATA_REV;
> -    EssData.X64.KnownGoodStackTop          = (UINTN)mNewStack + sizeof
> (mNewStack);
> -    EssData.X64.KnownGoodStackSize         =
> CPU_KNOWN_GOOD_STACK_SIZE;
> -    EssData.X64.StackSwitchExceptions      =
> CPU_STACK_SWITCH_EXCEPTION_LIST;
> -    EssData.X64.StackSwitchExceptionNumber =
> CPU_STACK_SWITCH_EXCEPTION_NUMBER;
> -    EssData.X64.IdtTable                   = (VOID *)Idtr.Base;
> -    EssData.X64.IdtTableSize               = Idtr.Limit + 1;
> -    EssData.X64.GdtTable                   = mNewGdt;
> -    EssData.X64.GdtTableSize               = sizeof (mNewGdt);
> -    EssData.X64.ExceptionTssDesc           = mNewGdt + Gdtr.Limit + 1;
> -    EssData.X64.ExceptionTssDescSize       = CPU_TSS_DESC_SIZE;
> -    EssData.X64.ExceptionTss               = mNewGdt + Gdtr.Limit + 1 +
> CPU_TSS_DESC_SIZE;
> -    EssData.X64.ExceptionTssSize           = CPU_TSS_SIZE;
> -
> -    InitData = &EssData;
> +    StackTop    = (UINTN)mNewStack + sizeof (mNewStack);
> +    NewGdtTable = mNewGdt;
> +  } else {
> +    if (BufferSize == NULL) {
> +      return EFI_INVALID_PARAMETER;
> +    }
> +
> +    NeedBufferSize = CPU_STACK_SWITCH_EXCEPTION_NUMBER *
> CPU_KNOWN_GOOD_STACK_SIZE + // Stack size
> +                     CPU_TSS_DESC_SIZE + CPU_TSS_SIZE + Gdtr.Limit + 1 +             //
> GDT size
> +                     sizeof (IA32_TSS_DESCRIPTOR);                                   // Make sure
> GDT table alignment
> +    if (*BufferSize < NeedBufferSize) {
> +      *BufferSize = NeedBufferSize;
> +      return EFI_BUFFER_TOO_SMALL;
> +    }
> +
> +    if (Buffer == NULL) {
> +      return EFI_INVALID_PARAMETER;
> +    }
> +
> +    StackTop    = (UINTN)Buffer +
> CPU_STACK_SWITCH_EXCEPTION_NUMBER *
> CPU_KNOWN_GOOD_STACK_SIZE;
> +    NewGdtTable = ALIGN_POINTER (StackTop, sizeof
> (IA32_TSS_DESCRIPTOR));
>    }
> 
> -  return ArchSetupExceptionStack (InitData);
> +  AsmReadIdtr (&Idtr);
> +  EssData.X64.KnownGoodStackTop          = StackTop;
> +  EssData.X64.KnownGoodStackSize         =
> CPU_KNOWN_GOOD_STACK_SIZE;
> +  EssData.X64.StackSwitchExceptions      =
> CPU_STACK_SWITCH_EXCEPTION_LIST;
> +  EssData.X64.StackSwitchExceptionNumber =
> CPU_STACK_SWITCH_EXCEPTION_NUMBER;
> +  EssData.X64.IdtTable                   = (VOID *)Idtr.Base; // Won't change IDT
> table in this function
> +  EssData.X64.IdtTableSize               = Idtr.Limit + 1;
> +  EssData.X64.GdtTable                   = NewGdtTable;
> +  EssData.X64.GdtTableSize               = CPU_TSS_DESC_SIZE + CPU_TSS_SIZE +
> Gdtr.Limit + 1;
> +  EssData.X64.ExceptionTssDesc           = NewGdtTable + Gdtr.Limit + 1;
> +  EssData.X64.ExceptionTssDescSize       = CPU_TSS_DESC_SIZE;
> +  EssData.X64.ExceptionTss               = NewGdtTable + Gdtr.Limit + 1 +
> CPU_TSS_DESC_SIZE;
> +  EssData.X64.ExceptionTssSize           = CPU_TSS_SIZE;
> +
> +  return ArchSetupExceptionStack (&EssData);
>  }
> diff --git
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.
> c
> index f13e8e7020..fa62074023 100644
> ---
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c
> +++
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.
> c
> @@ -1,7 +1,7 @@
>  /** @file
>    IA32 CPU Exception Handler functons.
> 
> -  Copyright (c) 2012 - 2019, Intel Corporation. All rights reserved.<BR>
> +  Copyright (c) 2012 - 2022, Intel Corporation. All rights reserved.<BR>
>    SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  **/
> @@ -132,7 +132,6 @@ ArchSetupExceptionStack (
>    EXCEPTION_HANDLER_TEMPLATE_MAP  TemplateMap;
> 
>    if ((StackSwitchData == NULL) ||
> -      (StackSwitchData->Ia32.Revision != CPU_EXCEPTION_INIT_DATA_REV)
> ||
>        (StackSwitchData->Ia32.KnownGoodStackTop == 0) ||
>        (StackSwitchData->Ia32.KnownGoodStackSize == 0) ||
>        (StackSwitchData->Ia32.StackSwitchExceptions == NULL) ||
> diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuException.c
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuException.c
> index 494c2ab433..2868560855 100644
> --- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuException.c
> +++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuException.c
> @@ -151,25 +151,71 @@ InitializeCpuExceptionHandlers (
> 
>  /**
>    Setup separate stacks for certain exception handlers.
> +  If the input Buffer and BufferSize are both NULL, use global variable if
> possible.
> 
> -  InitData is optional and processor arch dependent.
> -
> -  @param[in]  InitData      Pointer to data optional for information about how
> -                            to assign stacks for certain exception handlers.
> +  @param[in]       Buffer        Point to buffer used to separate exception stack.
> +  @param[in, out]  BufferSize    On input, it indicates the byte size of Buffer.
> +                                 If the size is not enough, the return status will
> +                                 be EFI_BUFFER_TOO_SMALL, and output BufferSize
> +                                 will be the size it needs.
> 
>    @retval EFI_SUCCESS             The stacks are assigned successfully.
>    @retval EFI_UNSUPPORTED         This function is not supported.
> -
> +  @retval EFI_BUFFER_TOO_SMALL    This BufferSize is too small.
>  **/
>  EFI_STATUS
>  EFIAPI
>  InitializeSeparateExceptionStacks (
> -  IN CPU_EXCEPTION_INIT_DATA  *InitData OPTIONAL
> +  IN     VOID   *Buffer,
> +  IN OUT UINTN  *BufferSize
>    )
>  {
> -  if (InitData == NULL) {
> +  CPU_EXCEPTION_INIT_DATA  EssData;
> +  IA32_DESCRIPTOR          Idtr;
> +  IA32_DESCRIPTOR          Gdtr;
> +  UINTN                    NeedBufferSize;
> +  UINTN                    StackTop;
> +  UINT8                    *NewGdtTable;
> +
> +  if ((Buffer == NULL) && (BufferSize == NULL)) {
>      return EFI_UNSUPPORTED;
>    }
> 
> -  return ArchSetupExceptionStack (InitData);
> +  if (BufferSize == NULL) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  AsmReadGdtr (&Gdtr);
> +
> +  NeedBufferSize = CPU_STACK_SWITCH_EXCEPTION_NUMBER *
> CPU_KNOWN_GOOD_STACK_SIZE +  // Stack size
> +                   CPU_TSS_DESC_SIZE + CPU_TSS_SIZE + Gdtr.Limit + 1 +              //
> GDT size
> +                   sizeof (IA32_TSS_DESCRIPTOR);                                    // Make sure
> GDT table alignment
> +
> +  if (*BufferSize < NeedBufferSize) {
> +    *BufferSize = NeedBufferSize;
> +    return EFI_BUFFER_TOO_SMALL;
> +  }
> +
> +  if (Buffer == NULL) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  StackTop    = (UINTN)Buffer + CPU_STACK_SWITCH_EXCEPTION_NUMBER
> * CPU_KNOWN_GOOD_STACK_SIZE;
> +  NewGdtTable = ALIGN_POINTER (StackTop, sizeof
> (IA32_TSS_DESCRIPTOR));
> +
> +  AsmReadIdtr (&Idtr);
> +  EssData.X64.KnownGoodStackTop          = StackTop;
> +  EssData.X64.KnownGoodStackSize         =
> CPU_KNOWN_GOOD_STACK_SIZE;
> +  EssData.X64.StackSwitchExceptions      =
> CPU_STACK_SWITCH_EXCEPTION_LIST;
> +  EssData.X64.StackSwitchExceptionNumber =
> CPU_STACK_SWITCH_EXCEPTION_NUMBER;
> +  EssData.X64.IdtTable                   = (VOID *)Idtr.Base; // Won't change IDT
> table in this function
> +  EssData.X64.IdtTableSize               = Idtr.Limit + 1;
> +  EssData.X64.GdtTable                   = NewGdtTable;
> +  EssData.X64.GdtTableSize               = CPU_TSS_DESC_SIZE + CPU_TSS_SIZE +
> Gdtr.Limit + 1;
> +  EssData.X64.ExceptionTssDesc           = NewGdtTable + Gdtr.Limit + 1;
> +  EssData.X64.ExceptionTssDescSize       = CPU_TSS_DESC_SIZE;
> +  EssData.X64.ExceptionTss               = NewGdtTable + Gdtr.Limit + 1 +
> CPU_TSS_DESC_SIZE;
> +  EssData.X64.ExceptionTssSize           = CPU_TSS_SIZE;
> +
> +  return ArchSetupExceptionStack (&EssData);
>  }
> diff --git
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuExceptionHandlerLib.i
> nf
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuExceptionHandlerLib.i
> nf
> index cf5bfe4083..7c2ec3b2db 100644
> ---
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuExceptionHandlerLib.i
> nf
> +++
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuExceptionHandlerLib.i
> nf
> @@ -1,7 +1,7 @@
>  ## @file
>  #  CPU Exception Handler library instance for PEI module.
>  #
> -#  Copyright (c) 2016 - 2018, Intel Corporation. All rights reserved.<BR>
> +#  Copyright (c) 2016 - 2022, Intel Corporation. All rights reserved.<BR>
>  #  SPDX-License-Identifier: BSD-2-Clause-Patent
>  #
>  ##
> @@ -56,6 +56,8 @@
> 
>  [Pcd]
>    gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard    # CONSUMES
> +  gUefiCpuPkgTokenSpaceGuid.PcdCpuKnownGoodStackSize
> +  gUefiCpuPkgTokenSpaceGuid.PcdCpuStackSwitchExceptionList
> 
>  [FeaturePcd]
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackGuard                    ##
> CONSUMES
> diff --git
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuException.c
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuException.c
> index 4313cc5582..ad5e0e9ed4 100644
> --- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuException.c
> +++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuException.c
> @@ -201,20 +201,23 @@ RegisterCpuInterruptHandler (
> 
>  /**
>    Setup separate stacks for certain exception handlers.
> +  If the input Buffer and BufferSize are both NULL, use global variable if
> possible.
> 
> -  InitData is optional and processor arch dependent.
> -
> -  @param[in]  InitData      Pointer to data optional for information about how
> -                            to assign stacks for certain exception handlers.
> +  @param[in]       Buffer        Point to buffer used to separate exception stack.
> +  @param[in, out]  BufferSize    On input, it indicates the byte size of Buffer.
> +                                 If the size is not enough, the return status will
> +                                 be EFI_BUFFER_TOO_SMALL, and output BufferSize
> +                                 will be the size it needs.
> 
>    @retval EFI_SUCCESS             The stacks are assigned successfully.
>    @retval EFI_UNSUPPORTED         This function is not supported.
> -
> +  @retval EFI_BUFFER_TOO_SMALL    This BufferSize is too small.
>  **/
>  EFI_STATUS
>  EFIAPI
>  InitializeSeparateExceptionStacks (
> -  IN CPU_EXCEPTION_INIT_DATA  *InitData OPTIONAL
> +  IN     VOID   *Buffer,
> +  IN OUT UINTN  *BufferSize
>    )
>  {
>    return EFI_UNSUPPORTED;
> diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/SmmException.c
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/SmmException.c
> index 1c97dab926..46a86ad2c6 100644
> --- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/SmmException.c
> +++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/SmmException.c
> @@ -97,20 +97,23 @@ RegisterCpuInterruptHandler (
> 
>  /**
>    Setup separate stacks for certain exception handlers.
> +  If the input Buffer and BufferSize are both NULL, use global variable if
> possible.
> 
> -  InitData is optional and processor arch dependent.
> -
> -  @param[in]  InitData      Pointer to data optional for information about how
> -                            to assign stacks for certain exception handlers.
> +  @param[in]       Buffer        Point to buffer used to separate exception stack.
> +  @param[in, out]  BufferSize    On input, it indicates the byte size of Buffer.
> +                                 If the size is not enough, the return status will
> +                                 be EFI_BUFFER_TOO_SMALL, and output BufferSize
> +                                 will be the size it needs.
> 
>    @retval EFI_SUCCESS             The stacks are assigned successfully.
>    @retval EFI_UNSUPPORTED         This function is not supported.
> -
> +  @retval EFI_BUFFER_TOO_SMALL    This BufferSize is too small.
>  **/
>  EFI_STATUS
>  EFIAPI
>  InitializeSeparateExceptionStacks (
> -  IN CPU_EXCEPTION_INIT_DATA  *InitData OPTIONAL
> +  IN     VOID   *Buffer,
> +  IN OUT UINTN  *BufferSize
>    )
>  {
>    return EFI_UNSUPPORTED;
> diff --git
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> index cd7dccd481..ff0dde4f12 100644
> ---
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> +++
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> @@ -1,7 +1,7 @@
>  /** @file
>    x64 CPU Exception Handler.
> 
> -  Copyright (c) 2012 - 2019, Intel Corporation. All rights reserved.<BR>
> +  Copyright (c) 2012 - 2022, Intel Corporation. All rights reserved.<BR>
>    SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  **/
> @@ -136,7 +136,6 @@ ArchSetupExceptionStack (
>    UINTN                     GdtSize;
> 
>    if ((StackSwitchData == NULL) ||
> -      (StackSwitchData->Ia32.Revision != CPU_EXCEPTION_INIT_DATA_REV)
> ||
>        (StackSwitchData->X64.KnownGoodStackTop == 0) ||
>        (StackSwitchData->X64.KnownGoodStackSize == 0) ||
>        (StackSwitchData->X64.StackSwitchExceptions == NULL) ||
> --
> 2.26.2.windows.1


  parent reply	other threads:[~2022-08-04  5:37 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-22  7:57 [PATCH 0/2] Simplify InitializeSeparateExceptionStacks Zhiguang Liu
2022-07-22  7:57 ` [PATCH 1/2] UefiCpuPkg: " Zhiguang Liu
2022-07-22 10:48   ` Sami Mujawar
2022-08-04  5:37   ` Ni, Ray [this message]
2022-07-22  7:57 ` [PATCH 2/2] MdeModulePkg: Move CPU_EXCEPTION_INIT_DATA to UefiCpuPkg Zhiguang Liu

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