code scrub for DebugSpport Module.

[mirror_edk2.git] / MdeModulePkg / Universal / DebugSupportDxe / X64 / PlDebugSupportX64.c

/** @file\r
  X64 specific debug support functions\r
\r
Copyright (c) 2006 - 2007, Intel Corporation\r
All rights reserved. This program and the accompanying materials\r
are licensed and made available under the terms and conditions of the BSD License\r
which accompanies this distribution.  The full text of the license may be found at\r
http://opensource.org/licenses/bsd-license.php\r
\r
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
**/\r
\r
#include "DebugSupport.h"\r
\r
/**\r
  Get Interrupt Handle from IDT Gate Descriptor.\r
\r
  @param  IdtGateDecriptor  IDT Gate Descriptor.\r
\r
  @return Interrupt Handle stored in IDT Gate Descriptor.\r
\r
**/\r
UINTN\r
GetInterruptHandleFromIdt (\r
  IN IA32_IDT_GATE_DESCRIPTOR  *IdtGateDecriptor\r
  )\r
{\r
  UINTN      InterruptHandle;\r
 \r
  ((UINT16 *) &InterruptHandle)[0] = (UINT16) IdtGateDecriptor->Bits.OffsetLow;\r
  ((UINT16 *) &InterruptHandle)[1] = (UINT16) IdtGateDecriptor->Bits.OffsetHigh;\r
  ((UINT32 *) &InterruptHandle)[1] = (UINT32) IdtGateDecriptor->Bits.OffsetUpper;\r
\r
  return InterruptHandle;\r
}\r
\r
/**\r
  Allocate pool for a new IDT entry stub.\r
\r
  Copy the generic stub into the new buffer and fixup the vector number\r
  and jump target address.\r
\r
  @param  ExceptionType   This is the exception type that the new stub will be created\r
                          for.\r
  @param  Stub            On successful exit, *Stub contains the newly allocated entry stub.\r
\r
**/\r
VOID\r
CreateEntryStub (\r
  IN EFI_EXCEPTION_TYPE     ExceptionType,\r
  OUT VOID                  **Stub\r
  )\r
{\r
  UINT8       *StubCopy;\r
\r
  StubCopy = *Stub;\r
\r
  //\r
  // Fixup the stub code for this vector\r
  //\r
\r
  // The stub code looks like this:\r
  //\r
  //    00000000  6A 00               push    0                       ; push vector number - will be modified before installed\r
  //    00000002  E9                  db      0e9h                    ; jump rel32\r
  //    00000003  00000000            dd      0                       ; fixed up to relative address of CommonIdtEntry\r
  //\r
\r
  //\r
  // poke in the exception type so the second push pushes the exception type\r
  //\r
  StubCopy[0x1] = (UINT8) ExceptionType;\r
\r
  //\r
  // fixup the jump target to point to the common entry\r
  //\r
  *(UINT32 *) &StubCopy[0x3] = (UINT32)((UINTN) CommonIdtEntry - (UINTN) &StubCopy[StubSize]);\r
\r
  return;\r
}\r
\r
/**\r
  This is the main worker function that manages the state of the interrupt\r
  handlers.  It both installs and uninstalls interrupt handlers based on the\r
  value of NewCallback.  If NewCallback is NULL, then uninstall is indicated.\r
  If NewCallback is non-NULL, then install is indicated.\r
\r
  @param  NewCallback   If non-NULL, NewCallback specifies the new handler to register.\r
                        If NULL, specifies that the previously registered handler should\r
                        be uninstalled.\r
  @param  ExceptionType Indicates which entry to manage.\r
\r
  @retval EFI_SUCCESS            Process is ok.\r
  @retval EFI_INVALID_PARAMETER  Requested uninstalling a handler from a vector that has\r
                                 no handler registered for it\r
  @retval EFI_ALREADY_STARTED    Requested install to a vector that already has a handler registered.\r
  @retval others                 Possible return values are passed through from UnHookEntry and HookEntry.\r
\r
**/\r
EFI_STATUS\r
ManageIdtEntryTable (\r
  VOID (*NewCallback)(),\r
  EFI_EXCEPTION_TYPE ExceptionType\r
  )\r
{\r
  EFI_STATUS  Status;\r
\r
  Status = EFI_SUCCESS;\r
\r
  if (CompareMem (&IdtEntryTable[ExceptionType].NewDesc, &NullDesc, sizeof (IA32_IDT_GATE_DESCRIPTOR)) != 0) {\r
    //\r
    // we've already installed to this vector\r
    //\r
    if (NewCallback != NULL) {\r
      //\r
      // if the input handler is non-null, error\r
      //\r
      Status = EFI_ALREADY_STARTED;\r
    } else {\r
      UnhookEntry (ExceptionType);\r
    }\r
  } else {\r
    //\r
    // no user handler installed on this vector\r
    //\r
    if (NewCallback == NULL) {\r
      //\r
      // if the input handler is null, error\r
      //\r
      Status = EFI_INVALID_PARAMETER;\r
    } else {\r
      HookEntry (ExceptionType, NewCallback);\r
    }\r
  }\r
 \r
  return Status;\r
}\r