MdeModulePkg/Universal/DebugSupportDxe/Ia32/PlDebugSupportIa32.c

   1 /** @file
   2   IA32 specific functions to support Debug Support protocol.
   3
   4 Copyright (c) 2008 - 2010, 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 "PlDebugSupport.h"
  16
  17 IA32_IDT_GATE_DESCRIPTOR  NullDesc = {{0}};
  18
  19 /**
  20   Get Interrupt Handle from IDT Gate Descriptor.
  21
  22   @param  IdtGateDescriptor  IDT Gate Descriptor.
  23
  24   @return Interrupt Handle stored in IDT Gate Descriptor.
  25
  26 **/
  27 UINTN
  28 GetInterruptHandleFromIdt (
  29   IN IA32_IDT_GATE_DESCRIPTOR  *IdtGateDescriptor
  30   )
  31 {
  32   UINTN      InterruptHandle;
  33
  34   //
  35   // InterruptHandle  0-15 : OffsetLow
  36   // InterruptHandle 16-31 : OffsetHigh
  37   //
  38   ((UINT16 *) &InterruptHandle)[0] = (UINT16) IdtGateDescriptor->Bits.OffsetLow;
  39   ((UINT16 *) &InterruptHandle)[1] = (UINT16) IdtGateDescriptor->Bits.OffsetHigh;
  40
  41   return InterruptHandle;
  42 }
  43
  44 /**
  45   Allocate pool for a new IDT entry stub.
  46
  47   Copy the generic stub into the new buffer and fixup the vector number
  48   and jump target address.
  49
  50   @param  ExceptionType   This is the exception type that the new stub will be created
  51                           for.
  52   @param  Stub            On successful exit, *Stub contains the newly allocated entry stub.
  53
  54 **/
  55 VOID
  56 CreateEntryStub (
  57   IN EFI_EXCEPTION_TYPE     ExceptionType,
  58   OUT VOID                  **Stub
  59   )
  60 {
  61   UINT8       *StubCopy;
  62
  63   StubCopy = *Stub;
  64
  65   //
  66   // Fixup the stub code for this vector
  67   //
  68
  69   // The stub code looks like this:
  70   //
  71   //    00000000  89 25 00000004 R  mov     AppEsp, esp             ; save stack top
  72   //    00000006  BC 00008014 R     mov     esp, offset DbgStkBot   ; switch to debugger stack
  73   //    0000000B  6A 00             push    0                       ; push vector number - will be modified before installed
  74   //    0000000D  E9                db      0e9h                    ; jump rel32
  75   //    0000000E  00000000          dd      0                       ; fixed up to relative address of CommonIdtEntry
  76   //
  77
  78   //
  79   // poke in the exception type so the second push pushes the exception type
  80   //
  81   StubCopy[0x0c] = (UINT8) ExceptionType;
  82
  83   //
  84   // fixup the jump target to point to the common entry
  85   //
  86   *(UINT32 *) &StubCopy[0x0e] = (UINT32) CommonIdtEntry - (UINT32) &StubCopy[StubSize];
  87
  88   return ;
  89 }
  90
  91 /**
  92   This is the main worker function that manages the state of the interrupt
  93   handlers.  It both installs and uninstalls interrupt handlers based on the
  94   value of NewCallback.  If NewCallback is NULL, then uninstall is indicated.
  95   If NewCallback is non-NULL, then install is indicated.
  96
  97   @param  NewCallback   If non-NULL, NewCallback specifies the new handler to register.
  98                         If NULL, specifies that the previously registered handler should
  99                         be uninstalled.
 100   @param  ExceptionType Indicates which entry to manage.
 101
 102   @retval EFI_SUCCESS            Installing or Uninstalling operation is ok.
 103   @retval EFI_INVALID_PARAMETER  Requested uninstalling a handler from a vector that has
 104                                  no handler registered for it
 105   @retval EFI_ALREADY_STARTED    Requested install to a vector that already has a handler registered.
 106
 107 **/
 108 EFI_STATUS
 109 ManageIdtEntryTable (
 110   CALLBACK_FUNC      NewCallback,
 111   EFI_EXCEPTION_TYPE ExceptionType
 112   )
 113 {
 114   EFI_STATUS  Status;
 115
 116   Status = EFI_SUCCESS;
 117
 118   if (CompareMem (&IdtEntryTable[ExceptionType].NewDesc, &NullDesc, sizeof (IA32_IDT_GATE_DESCRIPTOR)) != 0) {
 119     //
 120     // we've already installed to this vector
 121     //
 122     if (NewCallback != NULL) {
 123       //
 124       // if the input handler is non-null, error
 125       //
 126       Status = EFI_ALREADY_STARTED;
 127     } else {
 128       UnhookEntry (ExceptionType);
 129     }
 130   } else {
 131     //
 132     // no user handler installed on this vector
 133     //
 134     if (NewCallback == NULL) {
 135       //
 136       // if the input handler is null, error
 137       //
 138       Status = EFI_INVALID_PARAMETER;
 139     } else {
 140       HookEntry (ExceptionType, NewCallback);
 141     }
 142   }
 143
 144   return Status;
 145 }