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. All rights reserved.<BR>
   5 SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include "PlDebugSupport.h"
  10
  11 IA32_IDT_GATE_DESCRIPTOR  NullDesc = {{0}};
  12
  13 /**
  14   Get Interrupt Handle from IDT Gate Descriptor.
  15
  16   @param  IdtGateDescriptor  IDT Gate Descriptor.
  17
  18   @return Interrupt Handle stored in IDT Gate Descriptor.
  19
  20 **/
  21 UINTN
  22 GetInterruptHandleFromIdt (
  23   IN IA32_IDT_GATE_DESCRIPTOR  *IdtGateDescriptor
  24   )
  25 {
  26   UINTN      InterruptHandle;
  27
  28   //
  29   // InterruptHandle  0-15 : OffsetLow
  30   // InterruptHandle 16-31 : OffsetHigh
  31   //
  32   ((UINT16 *) &InterruptHandle)[0] = (UINT16) IdtGateDescriptor->Bits.OffsetLow;
  33   ((UINT16 *) &InterruptHandle)[1] = (UINT16) IdtGateDescriptor->Bits.OffsetHigh;
  34
  35   return InterruptHandle;
  36 }
  37
  38 /**
  39   Allocate pool for a new IDT entry stub.
  40
  41   Copy the generic stub into the new buffer and fixup the vector number
  42   and jump target address.
  43
  44   @param  ExceptionType   This is the exception type that the new stub will be created
  45                           for.
  46   @param  Stub            On successful exit, *Stub contains the newly allocated entry stub.
  47
  48 **/
  49 VOID
  50 CreateEntryStub (
  51   IN EFI_EXCEPTION_TYPE     ExceptionType,
  52   OUT VOID                  **Stub
  53   )
  54 {
  55   UINT8       *StubCopy;
  56
  57   StubCopy = *Stub;
  58
  59   //
  60   // Fixup the stub code for this vector
  61   //
  62
  63   // The stub code looks like this:
  64   //
  65   //    00000000  89 25 00000004 R  mov     AppEsp, esp             ; save stack top
  66   //    00000006  BC 00008014 R     mov     esp, offset DbgStkBot   ; switch to debugger stack
  67   //    0000000B  6A 00             push    0                       ; push vector number - will be modified before installed
  68   //    0000000D  E9                db      0e9h                    ; jump rel32
  69   //    0000000E  00000000          dd      0                       ; fixed up to relative address of CommonIdtEntry
  70   //
  71
  72   //
  73   // poke in the exception type so the second push pushes the exception type
  74   //
  75   StubCopy[0x0c] = (UINT8) ExceptionType;
  76
  77   //
  78   // fixup the jump target to point to the common entry
  79   //
  80   *(UINT32 *) &StubCopy[0x0e] = (UINT32) CommonIdtEntry - (UINT32) &StubCopy[StubSize];
  81
  82   return ;
  83 }
  84
  85 /**
  86   This is the main worker function that manages the state of the interrupt
  87   handlers.  It both installs and uninstalls interrupt handlers based on the
  88   value of NewCallback.  If NewCallback is NULL, then uninstall is indicated.
  89   If NewCallback is non-NULL, then install is indicated.
  90
  91   @param  NewCallback   If non-NULL, NewCallback specifies the new handler to register.
  92                         If NULL, specifies that the previously registered handler should
  93                         be uninstalled.
  94   @param  ExceptionType Indicates which entry to manage.
  95
  96   @retval EFI_SUCCESS            Installing or Uninstalling operation is ok.
  97   @retval EFI_INVALID_PARAMETER  Requested uninstalling a handler from a vector that has
  98                                  no handler registered for it
  99   @retval EFI_ALREADY_STARTED    Requested install to a vector that already has a handler registered.
 100
 101 **/
 102 EFI_STATUS
 103 ManageIdtEntryTable (
 104   CALLBACK_FUNC      NewCallback,
 105   EFI_EXCEPTION_TYPE ExceptionType
 106   )
 107 {
 108   EFI_STATUS  Status;
 109
 110   Status = EFI_SUCCESS;
 111
 112   if (CompareMem (&IdtEntryTable[ExceptionType].NewDesc, &NullDesc, sizeof (IA32_IDT_GATE_DESCRIPTOR)) != 0) {
 113     //
 114     // we've already installed to this vector
 115     //
 116     if (NewCallback != NULL) {
 117       //
 118       // if the input handler is non-null, error
 119       //
 120       Status = EFI_ALREADY_STARTED;
 121     } else {
 122       UnhookEntry (ExceptionType);
 123     }
 124   } else {
 125     //
 126     // no user handler installed on this vector
 127     //
 128     if (NewCallback == NULL) {
 129       //
 130       // if the input handler is null, error
 131       //
 132       Status = EFI_INVALID_PARAMETER;
 133     } else {
 134       HookEntry (ExceptionType, NewCallback);
 135     }
 136   }
 137
 138   return Status;
 139 }