/**@file
  IA32 specific debug support functions

Copyright (c) 2006 - 2007, 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;

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

--*/
{
  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;
}

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

--*/
{
  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

--*/
{
  BOOLEAN     OldIntFlagState;

  OldIntFlagState = WriteInterruptFlag (0);
  WriteIdt (ExceptionType, &(IdtEntryTable[ExceptionType].OrigDesc));
  WriteInterruptFlag (OldIntFlagState);

  return EFI_SUCCESS;
}

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.

--*/
{
  EFI_STATUS  Status;

  Status = EFI_SUCCESS;

  if (FeaturePcdGet (PcdNtEmulatorEnable)) {
    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);
      }
    }
  }

  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:
  This              - The DebugSupport instance
  MaxProcessorIndex - The maximuim supported processor index

Returns:
  Always returns EFI_SUCCESS with *MaxProcessorIndex set to 0

--*/
{
  *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:
  This             - The DebugSupport instance
  ProcessorIndex   - Which processor the callback applies to.
  PeriodicCallback - Callback function

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.

--*/
{
  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:
  This             - The DebugSupport instance
  ProcessorIndex   - Which processor the callback applies to.
  NewCallback      - Callback function
  ExceptionType    - Which exception to hook

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.

--*/
{
  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.
  Calls assembly routine to flush cache.

Arguments:
  This             - The DebugSupport instance
  ProcessorIndex   - Which processor the callback applies to.
  Start            - Physical base of the memory range to be invalidated
  Length           - mininum number of bytes in instruction cache to invalidate

Returns:

  EFI_SUCCESS - always return success

--*/
{
  AsmWbinvd ();
  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.
  EFI_OUT_OF_RESOURCES - not resource to finish initialization

--*/
{
  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;
}

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:

  EFI_SUCCESS - always return success

--*/
{
  EFI_EXCEPTION_TYPE  ExceptionType;

  for (ExceptionType = 0; ExceptionType < NUM_IDT_ENTRIES; ExceptionType++) {
    ManageIdtEntryTable (NULL, ExceptionType);
  }

  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:
  ExceptionType - exception type
  ContextRecord - system context

Returns:

  None

--*/
{
  if (IdtEntryTable[ExceptionType].RegisteredCallback != NULL) {
    if (ExceptionType != SYSTEM_TIMER_VECTOR) {
      IdtEntryTable[ExceptionType].RegisteredCallback (ExceptionType, ContextRecord);
    } else {
      OrigVector = IdtEntryTable[ExceptionType].OrigVector;
      IdtEntryTable[ExceptionType].RegisteredCallback (ContextRecord);
    }
  }
}