MdeModulePkg/Universal/DebugSupportDxe/X64/PlDebugSupportX64.c

   1 /** @file
   2   X64 specific debug support functions
   3
   4 Copyright (c) 2006 - 2007, Intel Corporation
   5 All rights reserved. This program and the accompanying materials
   6 are licensed and made available under the terms and conditions of the BSD License
   7 which accompanies this distribution.  The full text of the license may be found at
   8 http://opensource.org/licenses/bsd-license.php
   9
  10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 //
  16 // private header files
  17 //
  18 #include "DebugSupport.h"
  19
  20 /**
  21   Get Procedure Entry Point from IDT Gate Descriptor.
  22
  23   @param  IdtGateDecriptor  IDT Gate Descriptor.
  24
  25   @return Procedure Entry Point located in IDT Gate Descriptor.
  26
  27 **/
  28 UINTN GetProcedureEntryPoint (
  29   IN IA32_IDT_GATE_DESCRIPTOR  *IdtGateDecriptor
  30   )
  31 {
  32   UINTN      ProcedureEntryPoint;
  33
  34   ((UINT16 *) &ProcedureEntryPoint)[0] = (UINT16) IdtGateDecriptor->Bits.OffsetLow;
  35   ((UINT16 *) &ProcedureEntryPoint)[1] = (UINT16) IdtGateDecriptor->Bits.OffsetHigh;
  36   ((UINT32 *) &ProcedureEntryPoint)[1] = (UINT32) IdtGateDecriptor->Bits.OffsetUpper;
  37
  38   return ProcedureEntryPoint;
  39 }
  40
  41 /**
  42   Allocate pool for a new IDT entry stub.
  43
  44   Copy the generic stub into the new buffer and fixup the vector number
  45   and jump target address.
  46
  47   @param  ExceptionType   This is the exception type that the new stub will be created
  48                           for.
  49   @param  Stub            On successful exit, *Stub contains the newly allocated entry stub.
  50
  51   @retval EFI_SUCCESS     Always.
  52
  53 **/
  54 EFI_STATUS
  55 CreateEntryStub (
  56   IN EFI_EXCEPTION_TYPE     ExceptionType,
  57   OUT VOID                  **Stub
  58   )
  59 {
  60   UINT8       *StubCopy;
  61
  62   StubCopy = *Stub;
  63
  64   //
  65   // Fixup the stub code for this vector
  66   //
  67
  68   // The stub code looks like this:
  69   //
  70   //    00000000  6A 00               push    0                       ; push vector number - will be modified before installed
  71   //    00000002  E9                  db      0e9h                    ; jump rel32
  72   //    00000003  00000000            dd      0                       ; fixed up to relative address of CommonIdtEntry
  73   //
  74
  75   //
  76   // poke in the exception type so the second push pushes the exception type
  77   //
  78   StubCopy[0x1] = (UINT8) ExceptionType;
  79
  80   //
  81   // fixup the jump target to point to the common entry
  82   //
  83   *(UINT32 *) &StubCopy[0x3] = (UINT32)((UINTN) CommonIdtEntry - (UINTN) &StubCopy[StubSize]);
  84
  85   return EFI_SUCCESS;
  86 }
  87
  88 /**
  89   This is the main worker function that manages the state of the interrupt
  90   handlers.  It both installs and uninstalls interrupt handlers based on the
  91   value of NewCallback.  If NewCallback is NULL, then uninstall is indicated.
  92   If NewCallback is non-NULL, then install is indicated.
  93
  94   @param  NewCallback   If non-NULL, NewCallback specifies the new handler to register.
  95                         If NULL, specifies that the previously registered handler should
  96                         be uninstalled.
  97   @param  ExceptionType Indicates which entry to manage.
  98
  99   @retval EFI_SUCCESS            Process is ok.
 100   @retval EFI_INVALID_PARAMETER  Requested uninstalling a handler from a vector that has
 101                                  no handler registered for it
 102   @retval EFI_ALREADY_STARTED    Requested install to a vector that already has a handler registered.
 103   @retval others                 Possible return values are passed through from UnHookEntry and HookEntry.
 104
 105 **/
 106 EFI_STATUS
 107 ManageIdtEntryTable (
 108   VOID (*NewCallback)(),
 109   EFI_EXCEPTION_TYPE ExceptionType
 110   )
 111 {
 112   EFI_STATUS  Status;
 113
 114   Status = EFI_SUCCESS;
 115
 116   if (CompareMem (&IdtEntryTable[ExceptionType].NewDesc, &NullDesc, sizeof (IA32_IDT_GATE_DESCRIPTOR)) != 0) {
 117     //
 118     // we've already installed to this vector
 119     //
 120     if (NewCallback != NULL) {
 121       //
 122       // if the input handler is non-null, error
 123       //
 124       Status = EFI_ALREADY_STARTED;
 125     } else {
 126       Status = UnhookEntry (ExceptionType);
 127     }
 128   } else {
 129     //
 130     // no user handler installed on this vector
 131     //
 132     if (NewCallback == NULL) {
 133       //
 134       // if the input handler is null, error
 135       //
 136       Status = EFI_INVALID_PARAMETER;
 137     } else {
 138       Status = HookEntry (ExceptionType, NewCallback);
 139     }
 140   }
 141
 142   return Status;
 143 }