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 = {
  12   { 0 }
  13 };
  14
  15 /**
  16   Get Interrupt Handle from IDT Gate Descriptor.
  17
  18   @param  IdtGateDescriptor  IDT Gate Descriptor.
  19
  20   @return Interrupt Handle stored in IDT Gate Descriptor.
  21
  22 **/
  23 UINTN
  24 GetInterruptHandleFromIdt (
  25   IN IA32_IDT_GATE_DESCRIPTOR  *IdtGateDescriptor
  26   )
  27 {
  28   UINTN  InterruptHandle;
  29
  30   //
  31   // InterruptHandle  0-15 : OffsetLow
  32   // InterruptHandle 16-31 : OffsetHigh
  33   //
  34   ((UINT16 *)&InterruptHandle)[0] = (UINT16)IdtGateDescriptor->Bits.OffsetLow;
  35   ((UINT16 *)&InterruptHandle)[1] = (UINT16)IdtGateDescriptor->Bits.OffsetHigh;
  36
  37   return InterruptHandle;
  38 }
  39
  40 /**
  41   Allocate pool for a new IDT entry stub.
  42
  43   Copy the generic stub into the new buffer and fixup the vector number
  44   and jump target address.
  45
  46   @param  ExceptionType   This is the exception type that the new stub will be created
  47                           for.
  48   @param  Stub            On successful exit, *Stub contains the newly allocated entry stub.
  49
  50 **/
  51 VOID
  52 CreateEntryStub (
  53   IN EFI_EXCEPTION_TYPE  ExceptionType,
  54   OUT VOID               **Stub
  55   )
  56 {
  57   UINT8  *StubCopy;
  58
  59   StubCopy = *Stub;
  60
  61   //
  62   // Fixup the stub code for this vector
  63   //
  64
  65   // The stub code looks like this:
  66   //
  67   //    00000000  89 25 00000004 R  mov     AppEsp, esp             ; save stack top
  68   //    00000006  BC 00008014 R     mov     esp, offset DbgStkBot   ; switch to debugger stack
  69   //    0000000B  6A 00             push    0                       ; push vector number - will be modified before installed
  70   //    0000000D  E9                db      0e9h                    ; jump rel32
  71   //    0000000E  00000000          dd      0                       ; fixed up to relative address of CommonIdtEntry
  72   //
  73
  74   //
  75   // poke in the exception type so the second push pushes the exception type
  76   //
  77   StubCopy[0x0c] = (UINT8)ExceptionType;
  78
  79   //
  80   // fixup the jump target to point to the common entry
  81   //
  82   *(UINT32 *)&StubCopy[0x0e] = (UINT32)CommonIdtEntry - (UINT32)&StubCopy[StubSize];
  83
  84   return;
  85 }
  86
  87 /**
  88   This is the main worker function that manages the state of the interrupt
  89   handlers.  It both installs and uninstalls interrupt handlers based on the
  90   value of NewCallback.  If NewCallback is NULL, then uninstall is indicated.
  91   If NewCallback is non-NULL, then install is indicated.
  92
  93   @param  NewCallback   If non-NULL, NewCallback specifies the new handler to register.
  94                         If NULL, specifies that the previously registered handler should
  95                         be uninstalled.
  96   @param  ExceptionType Indicates which entry to manage.
  97
  98   @retval EFI_SUCCESS            Installing or Uninstalling operation is ok.
  99   @retval EFI_INVALID_PARAMETER  Requested uninstalling a handler from a vector that has
 100                                  no handler registered for it
 101   @retval EFI_ALREADY_STARTED    Requested install to a vector that already has a handler registered.
 102
 103 **/
 104 EFI_STATUS
 105 ManageIdtEntryTable (
 106   CALLBACK_FUNC       NewCallback,
 107   EFI_EXCEPTION_TYPE  ExceptionType
 108   )
 109 {
 110   EFI_STATUS  Status;
 111
 112   Status = EFI_SUCCESS;
 113
 114   if (CompareMem (&IdtEntryTable[ExceptionType].NewDesc, &NullDesc, sizeof (IA32_IDT_GATE_DESCRIPTOR)) != 0) {
 115     //
 116     // we've already installed to this vector
 117     //
 118     if (NewCallback != NULL) {
 119       //
 120       // if the input handler is non-null, error
 121       //
 122       Status = EFI_ALREADY_STARTED;
 123     } else {
 124       UnhookEntry (ExceptionType);
 125     }
 126   } else {
 127     //
 128     // no user handler installed on this vector
 129     //
 130     if (NewCallback == NULL) {
 131       //
 132       // if the input handler is null, error
 133       //
 134       Status = EFI_INVALID_PARAMETER;
 135     } else {
 136       HookEntry (ExceptionType, NewCallback);
 137     }
 138   }
 139
 140   return Status;
 141 }