SourceLevelDebugPkg/Library/PeCoffExtraActionLibDebug/Ia32/IntHandlerFuncs.c

   1 /** @file
   2   Ia32 arch functions to access IDT vector.
   3
   4   Copyright (c) 2013, Intel Corporation. All rights reserved.<BR>
   5   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 <PeCoffExtraActionLib.h>
  16
  17 /**
  18   Read IDT entry to check if IDT entries are setup by Debug Agent.
  19
  20   @param[in]  IdtDescriptor      Pointer to IDT Descriptor.
  21
  22   @retval  TRUE     IDT entries were setup by Debug Agent.
  23   @retval  FALSE    IDT entries were not setuo by Debug Agent.
  24
  25 **/
  26 BOOLEAN
  27 CheckDebugAgentHandler (
  28   IN  IA32_DESCRIPTOR            *IdtDescriptor
  29   )
  30 {
  31   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  32   UINTN                      InterruptHandler;
  33
  34   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
  35   if (IdtEntry == NULL) {
  36     return FALSE;
  37   }
  38
  39   InterruptHandler = IdtEntry[0].Bits.OffsetLow + (IdtEntry[0].Bits.OffsetHigh << 16);
  40   if (InterruptHandler >= 4 &&  *(UINT32 *)(InterruptHandler - 4) == AGENT_HANDLER_SIGNATURE) {
  41     return TRUE;
  42   } else {
  43     return FALSE;
  44   }
  45 }
  46
  47 /**
  48   Save IDT entry for INT1 and update it.
  49
  50   @param[in]  IdtDescriptor      Pointer to IDT Descriptor.
  51   @param[out] SavedIdtEntry      Original IDT entry returned.
  52
  53 **/
  54 VOID
  55 SaveAndUpdateIdtEntry1 (
  56   IN  IA32_DESCRIPTOR            *IdtDescriptor,
  57   OUT IA32_IDT_GATE_DESCRIPTOR   *SavedIdtEntry
  58   )
  59 {
  60   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  61   UINT16                     CodeSegment;
  62   UINTN                      InterruptHandler;
  63
  64   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
  65   CopyMem (SavedIdtEntry, &IdtEntry[1], sizeof (IA32_IDT_GATE_DESCRIPTOR));
  66
  67     //
  68   // Use current CS as the segment selector of interrupt gate in IDT
  69   //
  70   CodeSegment = AsmReadCs ();
  71
  72   InterruptHandler = (UINTN) &AsmInterruptHandle;
  73   IdtEntry[1].Bits.OffsetLow  = (UINT16)(UINTN)InterruptHandler;
  74   IdtEntry[1].Bits.OffsetHigh = (UINT16)((UINTN)InterruptHandler >> 16);
  75   IdtEntry[1].Bits.Selector   = CodeSegment;
  76   IdtEntry[1].Bits.GateType   = IA32_IDT_GATE_TYPE_INTERRUPT_32;
  77 }
  78
  79 /**
  80   Restore IDT entry for INT1.
  81
  82   @param[in]  IdtDescriptor      Pointer to IDT Descriptor.
  83   @param[in]  RestoredIdtEntry   IDT entry to be restored.
  84
  85 **/
  86 VOID
  87 RestoreIdtEntry1 (
  88   IN  IA32_DESCRIPTOR            *IdtDescriptor,
  89   IN  IA32_IDT_GATE_DESCRIPTOR   *RestoredIdtEntry
  90   )
  91 {
  92   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  93
  94   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
  95   CopyMem (&IdtEntry[1], RestoredIdtEntry, sizeof (IA32_IDT_GATE_DESCRIPTOR));
  96 }