path: root/MdeModulePkg/Universal/DebugSupportDxe/Ia32/PlDebugSupport.c

/** @file
  IA32 specific debug support functions

Copyright (c) 2006 - 2008, Intel Corporation
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution.  The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

//
// private header files
//
#include "PlDebugSupport.h"

//
// This the global main table to keep track of the interrupts
//
IDT_ENTRY   *IdtEntryTable  = NULL;
DESCRIPTOR  NullDesc        = 0;

/**
  Allocate pool for a new IDT entry stub.

  Copy the generic stub into the new buffer and fixup the vector number
  and jump target address.

  @param  ExceptionType   This is the exception type that the new stub will be created
                          for.
  @param  Stub            On successful exit, *Stub contains the newly allocated entry stub.

  @retval EFI_SUCCESS     Always.

**/
EFI_STATUS
CreateEntryStub (
  IN EFI_EXCEPTION_TYPE     ExceptionType,
  OUT VOID                  **Stub
  )
{
  UINT8       *StubCopy;

  StubCopy = *Stub;

  //
  // Fixup the stub code for this vector
  //

  // The stub code looks like this:
  //
  //    00000000  89 25 00000004 R  mov     AppEsp, esp             ; save stack top
  //    00000006  BC 00008014 R     mov     esp, offset DbgStkBot   ; switch to debugger stack
  //    0000000B  6A 00             push    0                       ; push vector number - will be modified before installed
  //    0000000D  E9                db      0e9h                    ; jump rel32
  //    0000000E  00000000          dd      0                       ; fixed up to relative address of CommonIdtEntry
  //

  //
  // poke in the exception type so the second push pushes the exception type
  //
  StubCopy[0x0c] = (UINT8) ExceptionType;

  //
  // fixup the jump target to point to the common entry
  //
  *(UINT32 *) &StubCopy[0x0e] = (UINT32) CommonIdtEntry - (UINT32) &StubCopy[StubSize];

  return EFI_SUCCESS;
}

/**
  Creates a nes entry stub.  Then saves the current IDT entry and replaces it
  with an interrupt gate for the new entry point.  The IdtEntryTable is updated
  with the new registered function.

  This code executes in boot services context.  The stub entry executes in interrupt
  context.

  @param  ExceptionType      Specifies which vector to hook.
  @param  NewCallback        A pointer to the new function to be registered.

  @retval EFI_SUCCESS        Always.

**/
EFI_STATUS
HookEntry (
  IN EFI_EXCEPTION_TYPE            ExceptionType,
  IN VOID                         (*NewCallback) ()
  )
{
  BOOLEAN     OldIntFlagState;
  EFI_STATUS  Status;

  Status = CreateEntryStub (ExceptionType, (VOID **) &IdtEntryTable[ExceptionType].StubEntry);
  if (Status == EFI_SUCCESS) {
    OldIntFlagState = WriteInterruptFlag (0);
    READ_IDT (ExceptionType, &(IdtEntryTable[ExceptionType].OrigDesc));

    ((UINT16 *) &IdtEntryTable[ExceptionType].OrigVector)[0]  = ((UINT16 *) &IdtEntryTable[ExceptionType].OrigDesc)[0];
    ((UINT16 *) &IdtEntryTable[ExceptionType].OrigVector)[1]  = ((UINT16 *) &IdtEntryTable[ExceptionType].OrigDesc)[3];

    Vect2Desc (&IdtEntryTable[ExceptionType].NewDesc, IdtEntryTable[ExceptionType].StubEntry);
    IdtEntryTable[ExceptionType].RegisteredCallback = NewCallback;
    WRITE_IDT (ExceptionType, &(IdtEntryTable[ExceptionType].NewDesc));
    WriteInterruptFlag (OldIntFlagState);
  }

  return Status;
}

/**
  Undoes HookEntry. This code executes in boot services context.

  @param  ExceptionType   Specifies which entry to unhook

  @retval EFI_SUCCESS     Always.

**/
EFI_STATUS
UnhookEntry (
  IN EFI_EXCEPTION_TYPE           ExceptionType
  )
{
  BOOLEAN     OldIntFlagState;

  OldIntFlagState = WriteInterruptFlag (0);
  WRITE_IDT (ExceptionType, &(IdtEntryTable[ExceptionType].OrigDesc));
  WriteInterruptFlag (OldIntFlagState);

  return EFI_SUCCESS;
}

/**
  This is the main worker function that manages the state of the interrupt
  handlers.  It both installs and uninstalls interrupt handlers based on the
  value of NewCallback.  If NewCallback is NULL, then uninstall is indicated.
  If NewCallback is non-NULL, then install is indicated.

  @param  NewCallback   If non-NULL, NewCallback specifies the new handler to register.
                        If NULL, specifies that the previously registered handler should
                        be uninstalled.
  @param  ExceptionType Indicates which entry to manage.

  @retval EFI_SUCCESS            Process is ok.
  @retval EFI_INVALID_PARAMETER  Requested uninstalling a handler from a vector that has
                                 no handler registered for it
  @retval EFI_ALREADY_STARTED    Requested install to a vector that already has a handler registered.
  @retval others                 Possible return values are passed through from UnHookEntry and HookEntry.

**/
EFI_STATUS
ManageIdtEntryTable (
  VOID (*NewCallback)(),
  EFI_EXCEPTION_TYPE ExceptionType
  )
{
  EFI_STATUS  Status;

  Status = EFI_SUCCESS;

  if (!FeaturePcdGet (PcdNtEmulatorEnable)) {
    if (COMPARE_DESCRIPTOR (&IdtEntryTable[ExceptionType].NewDesc, &NullDesc)) {
      //
      // we've already installed to this vector
      //
      if (NewCallback != NULL) {
        //
        // if the input handler is non-null, error
        //
        Status = EFI_ALREADY_STARTED;
      } else {
        Status = UnhookEntry (ExceptionType);
      }
    } else {
      //
      // no user handler installed on this vector
      //
      if (NewCallback == NULL) {
        //
        // if the input handler is null, error
        //
        Status = EFI_INVALID_PARAMETER;
      } else {
        Status = HookEntry (ExceptionType, NewCallback);
      }
    }
  }

  return Status;
}

/**
  This is a DebugSupport protocol member function, hard
  coded to support only 1 processor for now.

  @param  This                The DebugSupport instance
  @param  MaxProcessorIndex   The maximuim supported processor index

  @retval EFI_SUCCESS         Always returned with **MaxProcessorIndex set to 0.

**/
EFI_STATUS
EFIAPI
GetMaximumProcessorIndex (
  IN EFI_DEBUG_SUPPORT_PROTOCOL       *This,
  OUT UINTN                           *MaxProcessorIndex
  )
{
  *MaxProcessorIndex = 0;
  return (EFI_SUCCESS);
}

/**
  DebugSupport protocol member function.

  @param  This               The DebugSupport instance
  @param  ProcessorIndex     Which processor the callback applies to.
  @param  PeriodicCallback   Callback function

  @retval EFI_SUCCESS        Indicates the callback was registered.
  @retval others             Callback was not registered.

**/
EFI_STATUS
EFIAPI
RegisterPeriodicCallback (
  IN EFI_DEBUG_SUPPORT_PROTOCOL *This,
  IN UINTN                      ProcessorIndex,
  IN EFI_PERIODIC_CALLBACK      PeriodicCallback
  )
{
  return ManageIdtEntryTable (PeriodicCallback, SYSTEM_TIMER_VECTOR);
}

/**
  DebugSupport protocol member function.

  This code executes in boot services context.

  @param  This              The DebugSupport instance
  @param  ProcessorIndex    Which processor the callback applies to.
  @param  NewCallback       Callback function
  @param  ExceptionType     Which exception to hook

  @retval EFI_SUCCESS        Indicates the callback was registered.
  @retval others             Callback was not registered.

**/
EFI_STATUS
EFIAPI
RegisterExceptionCallback (
  IN EFI_DEBUG_SUPPORT_PROTOCOL *This,
  IN UINTN                      ProcessorIndex,
  IN EFI_EXCEPTION_CALLBACK     NewCallback,
  IN EFI_EXCEPTION_TYPE         ExceptionType
  )
{
  return ManageIdtEntryTable (NewCallback, ExceptionType);
}

/**
  DebugSupport protocol member function.  Calls assembly routine to flush cache.

  @param  This              The DebugSupport instance
  @param  ProcessorIndex    Which processor the callback applies to.
  @param  Start             Physical base of the memory range to be invalidated
  @param  Length            mininum number of bytes in instruction cache to invalidate

  @retval EFI_SUCCESS       Always returned.

**/
EFI_STATUS
EFIAPI
InvalidateInstructionCache (
  IN EFI_DEBUG_SUPPORT_PROTOCOL       *This,
  IN UINTN                            ProcessorIndex,
  IN VOID                             *Start,
  IN UINT64                           Length
  )
{
  AsmWbinvd ();
  return EFI_SUCCESS;
}

/**
  Initializes driver's handler registration databas. 
  
  This code executes in boot services context
  Must be public because it's referenced from DebugSupport.c

  @retval  EFI_UNSUPPORTED      If IA32 processor does not support FXSTOR/FXRSTOR instructions,
                                the context save will fail, so these processor's are not supported.
  @retval  EFI_OUT_OF_RESOURCES Fails to allocate memory.
  @retval  EFI_SUCCESS          Initializes successfully.

**/
EFI_STATUS
PlInitializeDebugSupportDriver (
  VOID
  )
{
  EFI_EXCEPTION_TYPE  ExceptionType;

  if (!FxStorSupport ()) {
    return EFI_UNSUPPORTED;
  }

  IdtEntryTable = AllocateZeroPool (sizeof (IDT_ENTRY) * NUM_IDT_ENTRIES);
  if (IdtEntryTable == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }

  for (ExceptionType = 0; ExceptionType < NUM_IDT_ENTRIES; ExceptionType++) {
    IdtEntryTable[ExceptionType].StubEntry = (DEBUG_PROC) (UINTN) AllocatePool (StubSize);
    if (IdtEntryTable[ExceptionType].StubEntry == NULL) {
      goto ErrorCleanup;
    }

    CopyMem ((VOID *)(UINTN)IdtEntryTable[ExceptionType].StubEntry, InterruptEntryStub, StubSize);
  }
  return EFI_SUCCESS;

ErrorCleanup:

  for (ExceptionType = 0; ExceptionType < NUM_IDT_ENTRIES; ExceptionType++) {
    if (IdtEntryTable[ExceptionType].StubEntry != NULL) {
      FreePool ((VOID *)(UINTN)IdtEntryTable[ExceptionType].StubEntry);
    }
  }
  FreePool (IdtEntryTable);

  return EFI_OUT_OF_RESOURCES;
}

/**
  This is the callback that is written to the LoadedImage protocol instance
  on the image handle. It uninstalls all registered handlers and frees all entry
  stub memory.

  @param  ImageHandle    The firmware allocated handle for the EFI image.

  @retval EFI_SUCCESS    Always.

**/
EFI_STATUS
EFIAPI
PlUnloadDebugSupportDriver (
  IN EFI_HANDLE ImageHandle
  )
{
  EFI_EXCEPTION_TYPE  ExceptionType;

  for (ExceptionType = 0; ExceptionType < NUM_IDT_ENTRIES; ExceptionType++) {
    ManageIdtEntryTable (NULL, ExceptionType);
  }

  FreePool (IdtEntryTable);
  return EFI_SUCCESS;
}

/**
  Common piece of code that invokes the registered handlers.

  This code executes in exception context so no efi calls are allowed.

  @param  ExceptionType     Exception type
  @param  ContextRecord     System context

**/
VOID
InterruptDistrubutionHub (
  EFI_EXCEPTION_TYPE      ExceptionType,
  EFI_SYSTEM_CONTEXT_IA32 *ContextRecord
  )
{
  if (IdtEntryTable[ExceptionType].RegisteredCallback != NULL) {
    if (ExceptionType != SYSTEM_TIMER_VECTOR) {
      IdtEntryTable[ExceptionType].RegisteredCallback (ExceptionType, ContextRecord);
    } else {
      OrigVector = IdtEntryTable[ExceptionType].OrigVector;
      IdtEntryTable[ExceptionType].RegisteredCallback (ContextRecord);
    }
  }
}