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

   1 /** @file
   2   Supporting functions for X64 architecture.
   3
   4   Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include "DebugAgent.h"
  10
  11 /**
  12   Initialize IDT entries to support source level debug.
  13
  14 **/
  15 VOID
  16 InitializeDebugIdt (
  17   VOID
  18   )
  19 {
  20   IA32_IDT_GATE_DESCRIPTOR  *IdtEntry;
  21   UINTN                     InterruptHandler;
  22   IA32_DESCRIPTOR           IdtDescriptor;
  23   UINTN                     Index;
  24   UINT16                    CodeSegment;
  25   UINT32                    RegEdx;
  26
  27   AsmReadIdtr (&IdtDescriptor);
  28
  29   //
  30   // Use current CS as the segment selector of interrupt gate in IDT
  31   //
  32   CodeSegment = AsmReadCs ();
  33
  34   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *)IdtDescriptor.Base;
  35
  36   for (Index = 0; Index < 20; Index++) {
  37     if (((PcdGet32 (PcdExceptionsIgnoredByDebugger) & ~(BIT1 | BIT3)) & (1 << Index)) != 0) {
  38       //
  39       // If the exception is masked to be reserved except for INT1 and INT3, skip it
  40       //
  41       continue;
  42     }
  43
  44     InterruptHandler                 = (UINTN)&Exception0Handle + Index * ExceptionStubHeaderSize;
  45     IdtEntry[Index].Bits.OffsetLow   = (UINT16)(UINTN)InterruptHandler;
  46     IdtEntry[Index].Bits.OffsetHigh  = (UINT16)((UINTN)InterruptHandler >> 16);
  47     IdtEntry[Index].Bits.OffsetUpper = (UINT32)((UINTN)InterruptHandler >> 32);
  48     IdtEntry[Index].Bits.Selector    = CodeSegment;
  49     IdtEntry[Index].Bits.GateType    = IA32_IDT_GATE_TYPE_INTERRUPT_32;
  50   }
  51
  52   InterruptHandler                              = (UINTN)&TimerInterruptHandle;
  53   IdtEntry[DEBUG_TIMER_VECTOR].Bits.OffsetLow   = (UINT16)(UINTN)InterruptHandler;
  54   IdtEntry[DEBUG_TIMER_VECTOR].Bits.OffsetHigh  = (UINT16)((UINTN)InterruptHandler >> 16);
  55   IdtEntry[DEBUG_TIMER_VECTOR].Bits.OffsetUpper = (UINT32)((UINTN)InterruptHandler >> 32);
  56   IdtEntry[DEBUG_TIMER_VECTOR].Bits.Selector    = CodeSegment;
  57   IdtEntry[DEBUG_TIMER_VECTOR].Bits.GateType    = IA32_IDT_GATE_TYPE_INTERRUPT_32;
  58
  59   //
  60   // If the CPU supports Debug Extensions(CPUID:01 EDX:BIT2), then
  61   // Set DE flag in CR4 to enable IO breakpoint
  62   //
  63   AsmCpuid (1, NULL, NULL, NULL, &RegEdx);
  64   if ((RegEdx & BIT2) != 0) {
  65     AsmWriteCr4 (AsmReadCr4 () | BIT3);
  66   }
  67 }
  68
  69 /**
  70   Retrieve exception handler from IDT table by ExceptionNum.
  71
  72   @param[in]  ExceptionNum    Exception number
  73
  74   @return Exception handler
  75
  76 **/
  77 VOID *
  78 GetExceptionHandlerInIdtEntry (
  79   IN UINTN  ExceptionNum
  80   )
  81 {
  82   IA32_IDT_GATE_DESCRIPTOR  *IdtEntry;
  83   IA32_DESCRIPTOR           IdtDescriptor;
  84
  85   AsmReadIdtr (&IdtDescriptor);
  86   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *)IdtDescriptor.Base;
  87
  88   return (VOID *)(IdtEntry[ExceptionNum].Bits.OffsetLow |
  89                   (((UINTN)IdtEntry[ExceptionNum].Bits.OffsetHigh) << 16) |
  90                   (((UINTN)IdtEntry[ExceptionNum].Bits.OffsetUpper) << 32));
  91 }
  92
  93 /**
  94   Set exception handler in IDT table by ExceptionNum.
  95
  96   @param[in]  ExceptionNum      Exception number
  97   @param[in]  ExceptionHandler  Exception Handler to be set
  98
  99 **/
 100 VOID
 101 SetExceptionHandlerInIdtEntry (
 102   IN UINTN  ExceptionNum,
 103   IN VOID   *ExceptionHandler
 104   )
 105 {
 106   IA32_IDT_GATE_DESCRIPTOR  *IdtEntry;
 107   IA32_DESCRIPTOR           IdtDescriptor;
 108
 109   AsmReadIdtr (&IdtDescriptor);
 110   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *)IdtDescriptor.Base;
 111
 112   IdtEntry[ExceptionNum].Bits.OffsetLow   = (UINT16)(UINTN)ExceptionHandler;
 113   IdtEntry[ExceptionNum].Bits.OffsetHigh  = (UINT16)((UINTN)ExceptionHandler >> 16);
 114   IdtEntry[ExceptionNum].Bits.OffsetUpper = (UINT32)((UINTN)ExceptionHandler >> 32);
 115 }