From a08e10aa1472c4e75edab7f4fd51a0a423ec4a8c Mon Sep 17 00:00:00 2001
From: Andrew Au <andrewau@microsoft.com>
Date: Fri, 12 Oct 2018 18:34:12 -0700
Subject: Stepping out of the write barrier

---
 src/debug/ee/controller.cpp | 16 ++++++++++++++--
 src/debug/ee/controller.h   | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 2 deletions(-)

(limited to 'src/debug')

diff --git a/src/debug/ee/controller.cpp b/src/debug/ee/controller.cpp
index b375e9e87c..a017c70b68 100644
--- a/src/debug/ee/controller.cpp
+++ b/src/debug/ee/controller.cpp
@@ -2733,8 +2733,6 @@ DPOSS_ACTION DebuggerController::ScanForTriggers(CORDB_ADDRESS_TYPE *address,
         DebuggerDataBreakpoint::TriggerDataBreakpoint(thread, context))
     {
         *pHitDataBp = true;
-        DebuggerDataBreakpoint *pDataBreakpoint = new (interopsafe) DebuggerDataBreakpoint(thread);
-        pDcq->dcqEnqueue(pDataBreakpoint, FALSE);
     }
 #endif
 
@@ -2955,6 +2953,7 @@ DPOSS_ACTION DebuggerController::DispatchPatchOrSingleStep(Thread *thread, CONTE
     if (hitDataBp)
     {
         PCODE ip = GetIP(context);
+        LOG((LF_CORDB|LF_ENC, LL_EVERYTHING, "DataBreakpoint: My current IP is %p.\n", ip));
 #if defined(_TARGET_X86_)
         bool withinWriteBarrierGroup = ((ip >= (PCODE) JIT_WriteBarrierGroup) && (ip <= (PCODE) JIT_WriteBarrierGroup_End));
         bool withinPatchedWriteBarrierGroup = ((ip >= (PCODE) JIT_PatchedWriteBarrierGroup) && (ip <= (PCODE) JIT_PatchedWriteBarrierGroup_End));
@@ -2983,6 +2982,19 @@ DPOSS_ACTION DebuggerController::DispatchPatchOrSingleStep(Thread *thread, CONTE
 #else
         // TODO - ARM/ARM64
 #endif
+        LOG((LF_CORDB|LF_ENC, LL_EVERYTHING, "DataBreakpoint: Unwound IP is %p.\n", GetIP(context)));
+        DebuggerDataBreakpoint *pDataBreakpoint = new (interopsafe) DebuggerDataBreakpoint(thread);
+        if (!stashedContext)
+        {
+            dcq.dcqEnqueue(pDataBreakpoint, FALSE);
+        }
+        else
+        {
+            pDataBreakpoint->AddAndActivateNativePatchForAddress((CORDB_ADDRESS_TYPE*)GetIP(context), FramePointer::MakeFramePointer(GetFP(context)), true, DPT_DEFAULT_TRACE_TYPE);
+            memcpy(context, &stash, sizeof(CONTEXT));
+            stashedContext = false;
+        }
+        LOG((LF_CORDB|LF_ENC, LL_EVERYTHING, "DataBreakpoint: Rewound IP is %p.\n", GetIP(context)));
     }
 
     LOG((LF_CORDB|LF_ENC, LL_EVERYTHING, "DC::DPOSS ScanForTriggers called and returned.\n"));
diff --git a/src/debug/ee/controller.h b/src/debug/ee/controller.h
index 4e81b847e4..1710001d10 100644
--- a/src/debug/ee/controller.h
+++ b/src/debug/ee/controller.h
@@ -1774,10 +1774,13 @@ private:
 
 class DebuggerDataBreakpoint : public DebuggerController
 {
+private:
+    CONTEXT context;
 public:
     DebuggerDataBreakpoint(Thread* pThread) : DebuggerController(pThread, NULL)
     {
         LOG((LF_CORDB, LL_INFO10000, "D:DDBP: Data Breakpoint event created\n"));
+        memcpy(&context, g_pEEInterface->GetThreadFilterContext(pThread), sizeof(CONTEXT));
     }
     
     virtual DEBUGGER_CONTROLLER_TYPE GetDCType(void)
@@ -1785,6 +1788,33 @@ public:
         return DEBUGGER_CONTROLLER_DATA_BREAKPOINT;
     }
 
+    virtual TP_RESULT TriggerPatch(DebuggerControllerPatch *patch,
+                              Thread *thread, 
+                              TRIGGER_WHY tyWhy)
+    {
+#ifndef FEATURE_PAL    
+#if defined(_TARGET_X86_) || defined(_TARGET_AMD64_)
+        CONTEXT *context = g_pEEInterface->GetThreadFilterContext(thread);
+#ifdef _TARGET_X86_
+        context->Dr0 = this->context.Dr0;
+        context->Dr1 = this->context.Dr1;
+        context->Dr2 = this->context.Dr2;
+        context->Dr3 = this->context.Dr3;
+        context->Dr6 = this->context.Dr6;
+        context->Dr7 = this->context.Dr7;
+#elif defined(_TARGET_AMD64_)
+        context->Dr0 = this->context.Dr0;
+        context->Dr1 = this->context.Dr1;
+        context->Dr2 = this->context.Dr2;
+        context->Dr3 = this->context.Dr3;
+        context->Dr6 = this->context.Dr6;
+        context->Dr7 = this->context.Dr7;
+#endif
+#endif
+#endif
+        return TPR_TRIGGER;
+    }
+
     bool SendEvent(Thread *thread, bool fInteruptedBySetIp)
     {
         CONTRACTL
@@ -1800,6 +1830,9 @@ public:
         CONTEXT *context = g_pEEInterface->GetThreadFilterContext(thread);
 
         g_pDebugger->SendDataBreakpoint(thread, context, this);
+
+        Delete();
+
         return true;
     }
 
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