MdeModulePkg/Universal/DebugSupportDxe/Ia32/PlDebugSupportIa32.c

   1 /** @file
   2   IA32 specific debug support functions
   3
   4 Copyright (c) 2006 - 2008, 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 #include "DebugSupport.h"
  16
  17 /**
  18   Get Procedure Entry Point from IDT Gate Descriptor.
  19
  20   @param  IdtGateDecriptor  IDT Gate Descriptor.
  21
  22   @return Procedure Entry Point located in IDT Gate Descriptor.
  23
  24 **/
  25 UINTN GetProcedureEntryPoint (
  26   IN IA32_IDT_GATE_DESCRIPTOR  *IdtGateDecriptor
  27   )
  28 {
  29   UINTN      ProcedureEntryPoint;
  30
  31   ((UINT16 *) &ProcedureEntryPoint)[0] = (UINT16) IdtGateDecriptor->Bits.OffsetLow;
  32   ((UINT16 *) &ProcedureEntryPoint)[1] = (UINT16) IdtGateDecriptor->Bits.OffsetHigh;
  33
  34   return ProcedureEntryPoint;
  35 }
  36
  37 /**
  38   Allocate pool for a new IDT entry stub.
  39
  40   Copy the generic stub into the new buffer and fixup the vector number
  41   and jump target address.
  42
  43   @param  ExceptionType   This is the exception type that the new stub will be created
  44                           for.
  45   @param  Stub            On successful exit, *Stub contains the newly allocated entry stub.
  46
  47   @retval EFI_SUCCESS     Always.
  48
  49 **/
  50 EFI_STATUS
  51 CreateEntryStub (
  52   IN EFI_EXCEPTION_TYPE     ExceptionType,
  53   OUT VOID                  **Stub
  54   )
  55 {
  56   UINT8       *StubCopy;
  57
  58   StubCopy = *Stub;
  59
  60   //
  61   // Fixup the stub code for this vector
  62   //
  63
  64   // The stub code looks like this:
  65   //
  66   //    00000000  89 25 00000004 R  mov     AppEsp, esp             ; save stack top
  67   //    00000006  BC 00008014 R     mov     esp, offset DbgStkBot   ; switch to debugger stack
  68   //    0000000B  6A 00             push    0                       ; push vector number - will be modified before installed
  69   //    0000000D  E9                db      0e9h                    ; jump rel32
  70   //    0000000E  00000000          dd      0                       ; fixed up to relative address of CommonIdtEntry
  71   //
  72
  73   //
  74   // poke in the exception type so the second push pushes the exception type
  75   //
  76   StubCopy[0x0c] = (UINT8) ExceptionType;
  77
  78   //
  79   // fixup the jump target to point to the common entry
  80   //
  81   *(UINT32 *) &StubCopy[0x0e] = (UINT32) CommonIdtEntry - (UINT32) &StubCopy[StubSize];
  82
  83   return EFI_SUCCESS;
  84 }
  85
  86 /**
  87   This is the main worker function that manages the state of the interrupt
  88   handlers.  It both installs and uninstalls interrupt handlers based on the
  89   value of NewCallback.  If NewCallback is NULL, then uninstall is indicated.
  90   If NewCallback is non-NULL, then install is indicated.
  91
  92   @param  NewCallback   If non-NULL, NewCallback specifies the new handler to register.
  93                         If NULL, specifies that the previously registered handler should
  94                         be uninstalled.
  95   @param  ExceptionType Indicates which entry to manage.
  96
  97   @retval EFI_SUCCESS            Process is ok.
  98   @retval EFI_INVALID_PARAMETER  Requested uninstalling a handler from a vector that has
  99                                  no handler registered for it
 100   @retval EFI_ALREADY_STARTED    Requested install to a vector that already has a handler registered.
 101   @retval others                 Possible return values are passed through from UnHookEntry and HookEntry.
 102
 103 **/
 104 EFI_STATUS
 105 ManageIdtEntryTable (
 106   VOID (*NewCallback)(),
 107   EFI_EXCEPTION_TYPE ExceptionType
 108   )
 109 {
 110   EFI_STATUS  Status;
 111
 112   Status = EFI_SUCCESS;
 113
 114   if (!FeaturePcdGet (PcdNtEmulatorEnable)) {
 115     if (CompareMem (&IdtEntryTable[ExceptionType].NewDesc, &NullDesc, sizeof (IA32_IDT_GATE_DESCRIPTOR)) != 0) {
 116       //
 117       // we've already installed to this vector
 118       //
 119       if (NewCallback != NULL) {
 120         //
 121         // if the input handler is non-null, error
 122         //
 123         Status = EFI_ALREADY_STARTED;
 124       } else {
 125         Status = UnhookEntry (ExceptionType);
 126       }
 127     } else {
 128       //
 129       // no user handler installed on this vector
 130       //
 131       if (NewCallback == NULL) {
 132         //
 133         // if the input handler is null, error
 134         //
 135         Status = EFI_INVALID_PARAMETER;
 136       } else {
 137         Status = HookEntry (ExceptionType, NewCallback);
 138       }
 139     }
 140   }
 141
 142   return Status;
 143 }