SourceLevelDebugPkg/Library/DebugAgent/DebugAgentCommon/X64/ArchDebugSupport.c

   1 /** @file
   2   Supporting functions for X64 architecture.
   3
   4   Copyright (c) 2010 - 2015, 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 "DebugAgent.h"
  16
  17 /**
  18   Initialize IDT entries to support source level debug.
  19
  20 **/
  21 VOID
  22 InitializeDebugIdt (
  23   VOID
  24   )
  25 {
  26   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  27   UINTN                      InterruptHandler;
  28   IA32_DESCRIPTOR            IdtDescriptor;
  29   UINTN                      Index;
  30   UINT16                     CodeSegment;
  31   UINT32                     RegEdx;
  32
  33   AsmReadIdtr (&IdtDescriptor);
  34
  35   //
  36   // Use current CS as the segment selector of interrupt gate in IDT
  37   //
  38   CodeSegment = AsmReadCs ();
  39
  40   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor.Base;
  41
  42   for (Index = 0; Index < 20; Index ++) {
  43     if (((PcdGet32 (PcdExceptionsIgnoredByDebugger) & ~(BIT1 | BIT3)) & (1 << Index)) != 0) {
  44       //
  45       // If the exception is masked to be reserved except for INT1 and INT3, skip it
  46       //
  47       continue;
  48     }
  49     InterruptHandler = (UINTN)&Exception0Handle + Index * ExceptionStubHeaderSize;
  50     IdtEntry[Index].Bits.OffsetLow       = (UINT16)(UINTN)InterruptHandler;
  51     IdtEntry[Index].Bits.OffsetHigh      = (UINT16)((UINTN)InterruptHandler >> 16);
  52     IdtEntry[Index].Bits.OffsetUpper     = (UINT32)((UINTN)InterruptHandler >> 32);
  53     IdtEntry[Index].Bits.Selector        = CodeSegment;
  54     IdtEntry[Index].Bits.GateType        = IA32_IDT_GATE_TYPE_INTERRUPT_32;
  55   }
  56
  57   InterruptHandler = (UINTN) &TimerInterruptHandle;
  58   IdtEntry[DEBUG_TIMER_VECTOR].Bits.OffsetLow       = (UINT16)(UINTN)InterruptHandler;
  59   IdtEntry[DEBUG_TIMER_VECTOR].Bits.OffsetHigh      = (UINT16)((UINTN)InterruptHandler >> 16);
  60   IdtEntry[DEBUG_TIMER_VECTOR].Bits.OffsetUpper     = (UINT32)((UINTN)InterruptHandler >> 32);
  61   IdtEntry[DEBUG_TIMER_VECTOR].Bits.Selector        = CodeSegment;
  62   IdtEntry[DEBUG_TIMER_VECTOR].Bits.GateType        = IA32_IDT_GATE_TYPE_INTERRUPT_32;
  63
  64   //
  65   // If the CPU supports Debug Extensions(CPUID:01 EDX:BIT2), then
  66   // Set DE flag in CR4 to enable IO breakpoint
  67   //
  68   AsmCpuid (1, NULL, NULL, NULL, &RegEdx);
  69   if ((RegEdx & BIT2) != 0) {
  70     AsmWriteCr4 (AsmReadCr4 () | BIT3);
  71   }
  72 }
  73
  74 /**
  75   Retrieve exception handler from IDT table by ExceptionNum.
  76
  77   @param[in]  ExceptionNum    Exception number
  78
  79   @return Exception handler
  80
  81 **/
  82 VOID *
  83 GetExceptionHandlerInIdtEntry (
  84   IN UINTN             ExceptionNum
  85   )
  86 {
  87   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  88   IA32_DESCRIPTOR            IdtDescriptor;
  89
  90   AsmReadIdtr (&IdtDescriptor);
  91   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor.Base;
  92
  93   return (VOID *) (IdtEntry[ExceptionNum].Bits.OffsetLow |
  94                   (((UINTN)IdtEntry[ExceptionNum].Bits.OffsetHigh) << 16) |
  95                   (((UINTN)IdtEntry[ExceptionNum].Bits.OffsetUpper) << 32));
  96 }
  97
  98 /**
  99   Set exception handler in IDT table by ExceptionNum.
 100
 101   @param[in]  ExceptionNum      Exception number
 102   @param[in]  ExceptionHandler  Exception Handler to be set
 103
 104 **/
 105 VOID
 106 SetExceptionHandlerInIdtEntry (
 107   IN UINTN             ExceptionNum,
 108   IN VOID              *ExceptionHandler
 109   )
 110 {
 111   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
 112   IA32_DESCRIPTOR            IdtDescriptor;
 113
 114   AsmReadIdtr (&IdtDescriptor);
 115   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor.Base;
 116
 117   IdtEntry[ExceptionNum].Bits.OffsetLow   = (UINT16)(UINTN)ExceptionHandler;
 118   IdtEntry[ExceptionNum].Bits.OffsetHigh  = (UINT16)((UINTN)ExceptionHandler >> 16);
 119   IdtEntry[ExceptionNum].Bits.OffsetUpper = (UINT32)((UINTN)ExceptionHandler >> 32);
 120 }