audk/UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeException.c

Ignoring revisions in .git-blame-ignore-revs. Click here to bypass and see the normal blame view.

138 lines
5.3 KiB
C
Raw Normal View History

/** @file
CPU exception handler library implemenation for DXE modules.
Copyright (c) 2013 - 2022, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <PiDxe.h>
#include "CpuExceptionCommon.h"
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>
CONST UINTN mDoFarReturnFlag = 0;
RESERVED_VECTORS_DATA mReservedVectorsData[CPU_INTERRUPT_NUM];
EFI_CPU_INTERRUPT_HANDLER mExternalInterruptHandlerTable[CPU_INTERRUPT_NUM];
EXCEPTION_HANDLER_DATA mExceptionHandlerData = {
CPU_INTERRUPT_NUM,
0, // To be fixed
mReservedVectorsData,
mExternalInterruptHandlerTable
};
UINT8 mBuffer[CPU_STACK_SWITCH_EXCEPTION_NUMBER * CPU_KNOWN_GOOD_STACK_SIZE
+ CPU_TSS_GDT_SIZE];
UefiCpuPkg/CpuExceptionHandlerLib: Add stack switch support If Stack Guard is enabled and there's really a stack overflow happened during boot, a Page Fault exception will be triggered. Because the stack is out of usage, the exception handler, which shares the stack with normal UEFI driver, cannot be executed and cannot dump the processor information. Without those information, it's very difficult for the BIOS developers locate the root cause of stack overflow. And without a workable stack, the developer cannot event use single step to debug the UEFI driver with JTAG debugger. In order to make sure the exception handler to execute normally after stack overflow. We need separate stacks for exception handlers in case of unusable stack. IA processor allows to switch to a new stack during handling interrupt and exception. But X64 and IA32 provides different ways to make it. X64 provides interrupt stack table (IST) to allow maximum 7 different exceptions to have new stack for its handler. IA32 doesn't have IST mechanism and can only use task gate to do it since task switch allows to load a new stack through its task-state segment (TSS). The new API, InitializeCpuExceptionHandlersEx, is implemented to complete extra initialization for stack switch of exception handler. Since setting up stack switch needs allocating new memory for new stack, new GDT table and task-state segment but the initialization method will be called in different phases which have no consistent way to reserve those memory, this new API is allowed to pass the reserved resources to complete the extra works. This is cannot be done by original InitializeCpuExceptionHandlers. Considering exception handler initialization for MP situation, this new API is also necessary, because AP is not supposed to allocate memory. So the memory needed for stack switch have to be reserved in BSP before waking up AP and then pass them to InitializeCpuExceptionHandlersEx afterwards. Since Stack Guard feature is available only for DXE phase at this time, the new API is fully implemented for DXE only. Other phases implement a dummy one which just calls InitializeCpuExceptionHandlers(). Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Cc: Michael Kinney <michael.d.kinney@intel.com> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Jeff Fan <vanjeff_919@hotmail.com> Reviewed-by: Jiewen.yao@intel.com
2017-12-07 13:15:12 +01:00
/**
Common exception handler.
@param ExceptionType Exception type.
@param SystemContext Pointer to EFI_SYSTEM_CONTEXT.
**/
VOID
EFIAPI
CommonExceptionHandler (
IN EFI_EXCEPTION_TYPE ExceptionType,
IN EFI_SYSTEM_CONTEXT SystemContext
)
{
CommonExceptionHandlerWorker (ExceptionType, SystemContext, &mExceptionHandlerData);
}
/**
Initializes all CPU exceptions entries and provides the default exception handlers.
Caller should try to get an array of interrupt and/or exception vectors that are in use and need to
persist by EFI_VECTOR_HANDOFF_INFO defined in PI 1.3 specification.
If caller cannot get reserved vector list or it does not exists, set VectorInfo to NULL.
If VectorInfo is not NULL, the exception vectors will be initialized per vector attribute accordingly.
@param[in] VectorInfo Pointer to reserved vector list.
@retval EFI_SUCCESS CPU Exception Entries have been successfully initialized
with default exception handlers.
@retval EFI_INVALID_PARAMETER VectorInfo includes the invalid content if VectorInfo is not NULL.
@retval EFI_UNSUPPORTED This function is not supported.
**/
EFI_STATUS
EFIAPI
InitializeCpuExceptionHandlers (
IN EFI_VECTOR_HANDOFF_INFO *VectorInfo OPTIONAL
)
{
InitializeSpinLock (&mExceptionHandlerData.DisplayMessageSpinLock);
return InitializeCpuExceptionHandlersWorker (VectorInfo, &mExceptionHandlerData);
}
/**
Registers a function to be called from the processor interrupt handler.
This function registers and enables the handler specified by InterruptHandler for a processor
interrupt or exception type specified by InterruptType. If InterruptHandler is NULL, then the
handler for the processor interrupt or exception type specified by InterruptType is uninstalled.
The installed handler is called once for each processor interrupt or exception.
NOTE: This function should be invoked after InitializeCpuExceptionHandlers() is invoked,
otherwise EFI_UNSUPPORTED returned.
@param[in] InterruptType Defines which interrupt or exception to hook.
@param[in] InterruptHandler A pointer to a function of type EFI_CPU_INTERRUPT_HANDLER that is called
when a processor interrupt occurs. If this parameter is NULL, then the handler
will be uninstalled.
@retval EFI_SUCCESS The handler for the processor interrupt was successfully installed or uninstalled.
@retval EFI_ALREADY_STARTED InterruptHandler is not NULL, and a handler for InterruptType was
previously installed.
@retval EFI_INVALID_PARAMETER InterruptHandler is NULL, and a handler for InterruptType was not
previously installed.
@retval EFI_UNSUPPORTED The interrupt specified by InterruptType is not supported,
or this function is not supported.
**/
EFI_STATUS
EFIAPI
RegisterCpuInterruptHandler (
IN EFI_EXCEPTION_TYPE InterruptType,
IN EFI_CPU_INTERRUPT_HANDLER InterruptHandler
)
{
return RegisterCpuInterruptHandlerWorker (InterruptType, InterruptHandler, &mExceptionHandlerData);
}
UefiCpuPkg/CpuExceptionHandlerLib: Add stack switch support If Stack Guard is enabled and there's really a stack overflow happened during boot, a Page Fault exception will be triggered. Because the stack is out of usage, the exception handler, which shares the stack with normal UEFI driver, cannot be executed and cannot dump the processor information. Without those information, it's very difficult for the BIOS developers locate the root cause of stack overflow. And without a workable stack, the developer cannot event use single step to debug the UEFI driver with JTAG debugger. In order to make sure the exception handler to execute normally after stack overflow. We need separate stacks for exception handlers in case of unusable stack. IA processor allows to switch to a new stack during handling interrupt and exception. But X64 and IA32 provides different ways to make it. X64 provides interrupt stack table (IST) to allow maximum 7 different exceptions to have new stack for its handler. IA32 doesn't have IST mechanism and can only use task gate to do it since task switch allows to load a new stack through its task-state segment (TSS). The new API, InitializeCpuExceptionHandlersEx, is implemented to complete extra initialization for stack switch of exception handler. Since setting up stack switch needs allocating new memory for new stack, new GDT table and task-state segment but the initialization method will be called in different phases which have no consistent way to reserve those memory, this new API is allowed to pass the reserved resources to complete the extra works. This is cannot be done by original InitializeCpuExceptionHandlers. Considering exception handler initialization for MP situation, this new API is also necessary, because AP is not supposed to allocate memory. So the memory needed for stack switch have to be reserved in BSP before waking up AP and then pass them to InitializeCpuExceptionHandlersEx afterwards. Since Stack Guard feature is available only for DXE phase at this time, the new API is fully implemented for DXE only. Other phases implement a dummy one which just calls InitializeCpuExceptionHandlers(). Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Cc: Michael Kinney <michael.d.kinney@intel.com> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Jeff Fan <vanjeff_919@hotmail.com> Reviewed-by: Jiewen.yao@intel.com
2017-12-07 13:15:12 +01:00
/**
CpuException: Add InitializeSeparateExceptionStacks Today InitializeCpuExceptionHandlersEx is called from three modules: 1. DxeCore (links to DxeCpuExceptionHandlerLib) DxeCore expects it initializes the IDT entries as well as assigning separate stacks for #DF and #PF. 2. CpuMpPei (links to PeiCpuExceptionHandlerLib) and CpuDxe (links to DxeCpuExceptionHandlerLib) It's called for each thread for only assigning separate stacks for #DF and #PF. The IDT entries initialization is skipped because caller sets InitData->X64.InitDefaultHandlers to FALSE. Additionally, SecPeiCpuExceptionHandlerLib, SmmCpuExceptionHandlerLib also implement such API and the behavior of the API is simply to initialize IDT entries only. Because it mixes the IDT entries initialization and separate stacks assignment for certain exception handlers together, in order to know whether the function call only initializes IDT entries, or assigns stacks, we need to check: 1. value of InitData->X64.InitDefaultHandlers 2. library instance This patch cleans up the code to separate the stack assignment to a new API: InitializeSeparateExceptionStacks(). Only when caller calls the new API, the separate stacks are assigned. With this change, the SecPei and Smm instance can return unsupported which gives caller a very clear status. The old API InitializeCpuExceptionHandlersEx() is removed in this patch. Because no platform module is consuming the old API, the impact is none. Signed-off-by: Ray Ni <ray.ni@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Jian J Wang <jian.j.wang@intel.com>
2022-05-20 13:12:35 +02:00
Setup separate stacks for certain exception handlers.
If the input Buffer and BufferSize are both NULL, use global variable if possible.
UefiCpuPkg/CpuExceptionHandlerLib: Add stack switch support If Stack Guard is enabled and there's really a stack overflow happened during boot, a Page Fault exception will be triggered. Because the stack is out of usage, the exception handler, which shares the stack with normal UEFI driver, cannot be executed and cannot dump the processor information. Without those information, it's very difficult for the BIOS developers locate the root cause of stack overflow. And without a workable stack, the developer cannot event use single step to debug the UEFI driver with JTAG debugger. In order to make sure the exception handler to execute normally after stack overflow. We need separate stacks for exception handlers in case of unusable stack. IA processor allows to switch to a new stack during handling interrupt and exception. But X64 and IA32 provides different ways to make it. X64 provides interrupt stack table (IST) to allow maximum 7 different exceptions to have new stack for its handler. IA32 doesn't have IST mechanism and can only use task gate to do it since task switch allows to load a new stack through its task-state segment (TSS). The new API, InitializeCpuExceptionHandlersEx, is implemented to complete extra initialization for stack switch of exception handler. Since setting up stack switch needs allocating new memory for new stack, new GDT table and task-state segment but the initialization method will be called in different phases which have no consistent way to reserve those memory, this new API is allowed to pass the reserved resources to complete the extra works. This is cannot be done by original InitializeCpuExceptionHandlers. Considering exception handler initialization for MP situation, this new API is also necessary, because AP is not supposed to allocate memory. So the memory needed for stack switch have to be reserved in BSP before waking up AP and then pass them to InitializeCpuExceptionHandlersEx afterwards. Since Stack Guard feature is available only for DXE phase at this time, the new API is fully implemented for DXE only. Other phases implement a dummy one which just calls InitializeCpuExceptionHandlers(). Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Cc: Michael Kinney <michael.d.kinney@intel.com> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Jeff Fan <vanjeff_919@hotmail.com> Reviewed-by: Jiewen.yao@intel.com
2017-12-07 13:15:12 +01:00
@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.
UefiCpuPkg/CpuExceptionHandlerLib: Add stack switch support If Stack Guard is enabled and there's really a stack overflow happened during boot, a Page Fault exception will be triggered. Because the stack is out of usage, the exception handler, which shares the stack with normal UEFI driver, cannot be executed and cannot dump the processor information. Without those information, it's very difficult for the BIOS developers locate the root cause of stack overflow. And without a workable stack, the developer cannot event use single step to debug the UEFI driver with JTAG debugger. In order to make sure the exception handler to execute normally after stack overflow. We need separate stacks for exception handlers in case of unusable stack. IA processor allows to switch to a new stack during handling interrupt and exception. But X64 and IA32 provides different ways to make it. X64 provides interrupt stack table (IST) to allow maximum 7 different exceptions to have new stack for its handler. IA32 doesn't have IST mechanism and can only use task gate to do it since task switch allows to load a new stack through its task-state segment (TSS). The new API, InitializeCpuExceptionHandlersEx, is implemented to complete extra initialization for stack switch of exception handler. Since setting up stack switch needs allocating new memory for new stack, new GDT table and task-state segment but the initialization method will be called in different phases which have no consistent way to reserve those memory, this new API is allowed to pass the reserved resources to complete the extra works. This is cannot be done by original InitializeCpuExceptionHandlers. Considering exception handler initialization for MP situation, this new API is also necessary, because AP is not supposed to allocate memory. So the memory needed for stack switch have to be reserved in BSP before waking up AP and then pass them to InitializeCpuExceptionHandlersEx afterwards. Since Stack Guard feature is available only for DXE phase at this time, the new API is fully implemented for DXE only. Other phases implement a dummy one which just calls InitializeCpuExceptionHandlers(). Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Cc: Michael Kinney <michael.d.kinney@intel.com> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Jeff Fan <vanjeff_919@hotmail.com> Reviewed-by: Jiewen.yao@intel.com
2017-12-07 13:15:12 +01:00
CpuException: Add InitializeSeparateExceptionStacks Today InitializeCpuExceptionHandlersEx is called from three modules: 1. DxeCore (links to DxeCpuExceptionHandlerLib) DxeCore expects it initializes the IDT entries as well as assigning separate stacks for #DF and #PF. 2. CpuMpPei (links to PeiCpuExceptionHandlerLib) and CpuDxe (links to DxeCpuExceptionHandlerLib) It's called for each thread for only assigning separate stacks for #DF and #PF. The IDT entries initialization is skipped because caller sets InitData->X64.InitDefaultHandlers to FALSE. Additionally, SecPeiCpuExceptionHandlerLib, SmmCpuExceptionHandlerLib also implement such API and the behavior of the API is simply to initialize IDT entries only. Because it mixes the IDT entries initialization and separate stacks assignment for certain exception handlers together, in order to know whether the function call only initializes IDT entries, or assigns stacks, we need to check: 1. value of InitData->X64.InitDefaultHandlers 2. library instance This patch cleans up the code to separate the stack assignment to a new API: InitializeSeparateExceptionStacks(). Only when caller calls the new API, the separate stacks are assigned. With this change, the SecPei and Smm instance can return unsupported which gives caller a very clear status. The old API InitializeCpuExceptionHandlersEx() is removed in this patch. Because no platform module is consuming the old API, the impact is none. Signed-off-by: Ray Ni <ray.ni@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Jian J Wang <jian.j.wang@intel.com>
2022-05-20 13:12:35 +02:00
@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.
UefiCpuPkg/CpuExceptionHandlerLib: Add stack switch support If Stack Guard is enabled and there's really a stack overflow happened during boot, a Page Fault exception will be triggered. Because the stack is out of usage, the exception handler, which shares the stack with normal UEFI driver, cannot be executed and cannot dump the processor information. Without those information, it's very difficult for the BIOS developers locate the root cause of stack overflow. And without a workable stack, the developer cannot event use single step to debug the UEFI driver with JTAG debugger. In order to make sure the exception handler to execute normally after stack overflow. We need separate stacks for exception handlers in case of unusable stack. IA processor allows to switch to a new stack during handling interrupt and exception. But X64 and IA32 provides different ways to make it. X64 provides interrupt stack table (IST) to allow maximum 7 different exceptions to have new stack for its handler. IA32 doesn't have IST mechanism and can only use task gate to do it since task switch allows to load a new stack through its task-state segment (TSS). The new API, InitializeCpuExceptionHandlersEx, is implemented to complete extra initialization for stack switch of exception handler. Since setting up stack switch needs allocating new memory for new stack, new GDT table and task-state segment but the initialization method will be called in different phases which have no consistent way to reserve those memory, this new API is allowed to pass the reserved resources to complete the extra works. This is cannot be done by original InitializeCpuExceptionHandlers. Considering exception handler initialization for MP situation, this new API is also necessary, because AP is not supposed to allocate memory. So the memory needed for stack switch have to be reserved in BSP before waking up AP and then pass them to InitializeCpuExceptionHandlersEx afterwards. Since Stack Guard feature is available only for DXE phase at this time, the new API is fully implemented for DXE only. Other phases implement a dummy one which just calls InitializeCpuExceptionHandlers(). Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Cc: Michael Kinney <michael.d.kinney@intel.com> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Jeff Fan <vanjeff_919@hotmail.com> Reviewed-by: Jiewen.yao@intel.com
2017-12-07 13:15:12 +01:00
**/
EFI_STATUS
EFIAPI
CpuException: Add InitializeSeparateExceptionStacks Today InitializeCpuExceptionHandlersEx is called from three modules: 1. DxeCore (links to DxeCpuExceptionHandlerLib) DxeCore expects it initializes the IDT entries as well as assigning separate stacks for #DF and #PF. 2. CpuMpPei (links to PeiCpuExceptionHandlerLib) and CpuDxe (links to DxeCpuExceptionHandlerLib) It's called for each thread for only assigning separate stacks for #DF and #PF. The IDT entries initialization is skipped because caller sets InitData->X64.InitDefaultHandlers to FALSE. Additionally, SecPeiCpuExceptionHandlerLib, SmmCpuExceptionHandlerLib also implement such API and the behavior of the API is simply to initialize IDT entries only. Because it mixes the IDT entries initialization and separate stacks assignment for certain exception handlers together, in order to know whether the function call only initializes IDT entries, or assigns stacks, we need to check: 1. value of InitData->X64.InitDefaultHandlers 2. library instance This patch cleans up the code to separate the stack assignment to a new API: InitializeSeparateExceptionStacks(). Only when caller calls the new API, the separate stacks are assigned. With this change, the SecPei and Smm instance can return unsupported which gives caller a very clear status. The old API InitializeCpuExceptionHandlersEx() is removed in this patch. Because no platform module is consuming the old API, the impact is none. Signed-off-by: Ray Ni <ray.ni@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Jian J Wang <jian.j.wang@intel.com>
2022-05-20 13:12:35 +02:00
InitializeSeparateExceptionStacks (
IN VOID *Buffer,
IN OUT UINTN *BufferSize
UefiCpuPkg/CpuExceptionHandlerLib: Add stack switch support If Stack Guard is enabled and there's really a stack overflow happened during boot, a Page Fault exception will be triggered. Because the stack is out of usage, the exception handler, which shares the stack with normal UEFI driver, cannot be executed and cannot dump the processor information. Without those information, it's very difficult for the BIOS developers locate the root cause of stack overflow. And without a workable stack, the developer cannot event use single step to debug the UEFI driver with JTAG debugger. In order to make sure the exception handler to execute normally after stack overflow. We need separate stacks for exception handlers in case of unusable stack. IA processor allows to switch to a new stack during handling interrupt and exception. But X64 and IA32 provides different ways to make it. X64 provides interrupt stack table (IST) to allow maximum 7 different exceptions to have new stack for its handler. IA32 doesn't have IST mechanism and can only use task gate to do it since task switch allows to load a new stack through its task-state segment (TSS). The new API, InitializeCpuExceptionHandlersEx, is implemented to complete extra initialization for stack switch of exception handler. Since setting up stack switch needs allocating new memory for new stack, new GDT table and task-state segment but the initialization method will be called in different phases which have no consistent way to reserve those memory, this new API is allowed to pass the reserved resources to complete the extra works. This is cannot be done by original InitializeCpuExceptionHandlers. Considering exception handler initialization for MP situation, this new API is also necessary, because AP is not supposed to allocate memory. So the memory needed for stack switch have to be reserved in BSP before waking up AP and then pass them to InitializeCpuExceptionHandlersEx afterwards. Since Stack Guard feature is available only for DXE phase at this time, the new API is fully implemented for DXE only. Other phases implement a dummy one which just calls InitializeCpuExceptionHandlers(). Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Cc: Michael Kinney <michael.d.kinney@intel.com> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Jeff Fan <vanjeff_919@hotmail.com> Reviewed-by: Jiewen.yao@intel.com
2017-12-07 13:15:12 +01:00
)
{
UINTN LocalBufferSize;
EFI_STATUS Status;
if ((Buffer == NULL) && (BufferSize == NULL)) {
SetMem (mBuffer, sizeof (mBuffer), 0);
LocalBufferSize = sizeof (mBuffer);
Status = ArchSetupExceptionStack (mBuffer, &LocalBufferSize);
ASSERT_EFI_ERROR (Status);
return Status;
} else {
return ArchSetupExceptionStack (Buffer, BufferSize);
UefiCpuPkg/CpuExceptionHandlerLib: Add stack switch support If Stack Guard is enabled and there's really a stack overflow happened during boot, a Page Fault exception will be triggered. Because the stack is out of usage, the exception handler, which shares the stack with normal UEFI driver, cannot be executed and cannot dump the processor information. Without those information, it's very difficult for the BIOS developers locate the root cause of stack overflow. And without a workable stack, the developer cannot event use single step to debug the UEFI driver with JTAG debugger. In order to make sure the exception handler to execute normally after stack overflow. We need separate stacks for exception handlers in case of unusable stack. IA processor allows to switch to a new stack during handling interrupt and exception. But X64 and IA32 provides different ways to make it. X64 provides interrupt stack table (IST) to allow maximum 7 different exceptions to have new stack for its handler. IA32 doesn't have IST mechanism and can only use task gate to do it since task switch allows to load a new stack through its task-state segment (TSS). The new API, InitializeCpuExceptionHandlersEx, is implemented to complete extra initialization for stack switch of exception handler. Since setting up stack switch needs allocating new memory for new stack, new GDT table and task-state segment but the initialization method will be called in different phases which have no consistent way to reserve those memory, this new API is allowed to pass the reserved resources to complete the extra works. This is cannot be done by original InitializeCpuExceptionHandlers. Considering exception handler initialization for MP situation, this new API is also necessary, because AP is not supposed to allocate memory. So the memory needed for stack switch have to be reserved in BSP before waking up AP and then pass them to InitializeCpuExceptionHandlersEx afterwards. Since Stack Guard feature is available only for DXE phase at this time, the new API is fully implemented for DXE only. Other phases implement a dummy one which just calls InitializeCpuExceptionHandlers(). Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Laszlo Ersek <lersek@redhat.com> Cc: Michael Kinney <michael.d.kinney@intel.com> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Jeff Fan <vanjeff_919@hotmail.com> Reviewed-by: Jiewen.yao@intel.com
2017-12-07 13:15:12 +01:00
}
}