/*++

Copyright (c) 2006, 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.             

Module Name:

    plDebugSupport.c

Abstract:

    IA32 specific debug support functions

Revision History

--*/

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

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

#ifndef EFI_NT_EMULATOR
STATIC
EFI_STATUS
CreateEntryStub (
  IN EFI_EXCEPTION_TYPE     ExceptionType,
  OUT VOID                  **Stub
  )
/*++

Routine Description: 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.

Arguments:
    ExceptionType - This is the exception type that the new stub will be created
                    for.
    Stub - On successful exit, *Stub contains the newly allocated entry stub.
Returns:
  Typically EFI_SUCCESS
  other possibilities are passed through from AllocatePool

--*/
{
  EFI_STATUS  Status;
  UINT8       *StubCopy;

  //
  // First, allocate a new buffer and copy the stub code into it
  //
  Status = gBS->AllocatePool (EfiBootServicesData, StubSize, Stub);
  if (Status == EFI_SUCCESS) {
    StubCopy = *Stub;
    gBS->CopyMem (StubCopy, InterruptEntryStub, StubSize);

    //
    // Next 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 Status;
}

STATIC
EFI_STATUS
HookEntry (
  IN EFI_EXCEPTION_TYPE            ExceptionType,
  IN VOID                         (*NewCallback) ()
  )
/*++

Routine Description:
  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.

Arguments:
  ExceptionType - specifies which vector to hook.
  NewCallback - a pointer to the new function to be registered.

Returns:
  EFI_SUCCESS
  Other possibilities are passed through by CreateEntryStub

--*/
// TODO:    ) - add argument and description to function comment
{
  BOOLEAN     OldIntFlagState;
  EFI_STATUS  Status;

  Status = CreateEntryStub (ExceptionType, (VOID **) &IdtEntryTable[ExceptionType].StubEntry);
  if (Status == EFI_SUCCESS) {
    OldIntFlagState = WriteInterruptFlag (0);
    ReadIdt (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;
    WriteIdt (ExceptionType, &(IdtEntryTable[ExceptionType].NewDesc));
    WriteInterruptFlag (OldIntFlagState);
  }

  return Status;
}

STATIC
EFI_STATUS
UnhookEntry (
  IN EFI_EXCEPTION_TYPE           ExceptionType
  )
/*++

Routine Description:
  Undoes HookEntry. This code executes in boot services context.

Arguments:
  ExceptionType - specifies which entry to unhook

Returns:
  EFI_SUCCESS
  Other values are passed through from FreePool

--*/
{
  BOOLEAN     OldIntFlagState;
  EFI_STATUS  Status;

  OldIntFlagState = WriteInterruptFlag (0);
  WriteIdt (ExceptionType, &(IdtEntryTable[ExceptionType].OrigDesc));
  Status = gBS->FreePool ((VOID *) (UINTN) IdtEntryTable[ExceptionType].StubEntry);
  ZeroMem (&IdtEntryTable[ExceptionType], sizeof (IDT_ENTRY));
  WriteInterruptFlag (OldIntFlagState);

  return (Status);
}
#endif

EFI_STATUS
ManageIdtEntryTable (
  VOID (*NewCallback)(),
  EFI_EXCEPTION_TYPE ExceptionType
  )
/*++

Routine Description:
  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.

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

Returns:
  EFI_SUCCESS
  EFI_INVALID_PARAMETER - requested uninstalling a handler from a vector that has
                          no handler registered for it
  EFI_ALREADY_STARTED   - requested install to a vector that already has a handler registered.

  Other possible return values are passed through from UnHookEntry and HookEntry.

--*/
// TODO:    ) - add argument and description to function comment
{
  EFI_STATUS  Status;

  Status = EFI_SUCCESS;

#ifndef EFI_NT_EMULATOR
  if (CompareDescriptor (&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);
    }
  }
#endif
  return Status;
}

EFI_STATUS
EFIAPI
GetMaximumProcessorIndex (
  IN EFI_DEBUG_SUPPORT_PROTOCOL       *This,
  OUT UINTN                           *MaxProcessorIndex
  )
/*++

Routine Description: This is a DebugSupport protocol member function.

Arguments:

Returns: Always returns EFI_SUCCESS with *MaxProcessorIndex set to 0

--*/
// TODO:    This - add argument and description to function comment
// TODO:    MaxProcessorIndex - add argument and description to function comment
{
  *MaxProcessorIndex = 0;
  return (EFI_SUCCESS);
}

EFI_STATUS
EFIAPI
RegisterPeriodicCallback (
  IN EFI_DEBUG_SUPPORT_PROTOCOL *This,
  IN UINTN                      ProcessorIndex,
  IN EFI_PERIODIC_CALLBACK      PeriodicCallback
  )
/*++

Routine Description: This is a DebugSupport protocol member function.

Arguments:

Returns:

--*/
// TODO:    This - add argument and description to function comment
// TODO:    ProcessorIndex - add argument and description to function comment
// TODO:    PeriodicCallback - add argument and description to function comment
{
  return ManageIdtEntryTable (PeriodicCallback, SYSTEM_TIMER_VECTOR);
}

EFI_STATUS
EFIAPI
RegisterExceptionCallback (
  IN EFI_DEBUG_SUPPORT_PROTOCOL *This,
  IN UINTN                      ProcessorIndex,
  IN EFI_EXCEPTION_CALLBACK     NewCallback,
  IN EFI_EXCEPTION_TYPE         ExceptionType
  )
/*++

Routine Description:
  This is a DebugSupport protocol member function.

  This code executes in boot services context.

Arguments:

Returns:

  None

--*/
// TODO:    This - add argument and description to function comment
// TODO:    ProcessorIndex - add argument and description to function comment
// TODO:    NewCallback - add argument and description to function comment
// TODO:    ExceptionType - add argument and description to function comment
{
  return ManageIdtEntryTable (NewCallback, ExceptionType);
}

EFI_STATUS
EFIAPI
InvalidateInstructionCache (
  IN EFI_DEBUG_SUPPORT_PROTOCOL       *This,
  IN UINTN                            ProcessorIndex,
  IN VOID                             *Start,
  IN UINT64                           Length
  )
/*++

Routine Description:
  This is a DebugSupport protocol member function.
  For IA32, this is a no-op since the instruction and data caches are coherent.

Arguments:

Returns:

  None

--*/
// TODO:    This - add argument and description to function comment
// TODO:    ProcessorIndex - add argument and description to function comment
// TODO:    Start - add argument and description to function comment
// TODO:    Length - add argument and description to function comment
// TODO:    EFI_SUCCESS - add return value to function comment
{
  return EFI_SUCCESS;
}

EFI_STATUS
plInitializeDebugSupportDriver (
  VOID
  )
/*++

Routine Description:
  Initializes driver's handler registration database.

  This code executes in boot services context.

Arguments:
  None

Returns:
  EFI_SUCCESS
  EFI_UNSUPPORTED - if IA32 processor does not support FXSTOR/FXRSTOR instructions,
                    the context save will fail, so these processor's are not supported.

--*/
// TODO:    EFI_OUT_OF_RESOURCES - add return value to function comment
{
  if (!FxStorSupport ()) {
    return EFI_UNSUPPORTED;
  } else {
    IdtEntryTable = AllocateZeroPool (sizeof (IDT_ENTRY) * NUM_IDT_ENTRIES);
    if (IdtEntryTable != NULL) {
      return EFI_SUCCESS;
    } else {
      return EFI_OUT_OF_RESOURCES;
    }
  }
}

EFI_STATUS
EFIAPI
plUnloadDebugSupportDriver (
  IN EFI_HANDLE ImageHandle
  )
/*++

Routine Description:
  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.

  This code executes in boot services context.

Arguments:
  ImageHandle - The image handle of the unload handler

Returns:

  None

--*/
// TODO:    EFI_SUCCESS - add return value to function comment
{
  EFI_EXCEPTION_TYPE  ExceptionType;

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

  gBS->FreePool (IdtEntryTable);
  return EFI_SUCCESS;
}

VOID
InterruptDistrubutionHub (
  EFI_EXCEPTION_TYPE      ExceptionType,
  EFI_SYSTEM_CONTEXT_IA32 *ContextRecord
  )
/*++

Routine Description: Common piece of code that invokes the registered handlers.

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

Arguments:

Returns:

  None

--*/
// TODO:    ExceptionType - add argument and description to function comment
// TODO:    ContextRecord - add argument and description to function comment
{
  if (IdtEntryTable[ExceptionType].RegisteredCallback != NULL) {
    if (ExceptionType != SYSTEM_TIMER_VECTOR) {
      IdtEntryTable[ExceptionType].RegisteredCallback (ExceptionType, ContextRecord);
    } else {
      OrigVector = IdtEntryTable[ExceptionType].OrigVector;
      IdtEntryTable[ExceptionType].RegisteredCallback (ContextRecord);
    }
  }
}