Support managed debugging when CET is enabled

src/coreclr/clrdefinitions.cmake

@@ -62,6 +62,10 @@ if(CLR_CMAKE_TARGET_ARCH_AMD64 OR CLR_CMAKE_TARGET_ARCH_I386 OR CLR_CMAKE_TARGET
   endif(CLR_CMAKE_TARGET_WIN32)
 endif(CLR_CMAKE_TARGET_ARCH_AMD64 OR CLR_CMAKE_TARGET_ARCH_I386 OR CLR_CMAKE_TARGET_ARCH_ARM64)
 
+if(CLR_CMAKE_TARGET_WIN32 AND CLR_CMAKE_TARGET_ARCH_AMD64)
+add_compile_definitions(OUT_OF_PROCESS_SETTHREADCONTEXT)
+endif(CLR_CMAKE_TARGET_WIN32)
+
 # Features - please keep them alphabetically sorted
 if(CLR_CMAKE_TARGET_WIN32)
   if(NOT CLR_CMAKE_TARGET_ARCH_I386)

src/coreclr/debug/di/process.cpp

@@ -7661,6 +7661,8 @@ HRESULT CordbProcess::GetRuntimeOffsets()
          m_runtimeOffsets.m_debuggerWordTLSIndex));
 #endif // FEATURE_INTEROP_DEBUGGING
 
+    LOG((LF_CORDB, LL_INFO10000, "    m_setThreadContextNeededAddr=     0x%p\n",
+         m_runtimeOffsets.m_setThreadContextNeededAddr));
     LOG((LF_CORDB, LL_INFO10000, "    m_TLSIndex=                       0x%08x\n",
          m_runtimeOffsets.m_TLSIndex));
     LOG((LF_CORDB, LL_INFO10000, "    m_EEThreadStateOffset=            0x%08x\n",
@@ -7719,6 +7721,7 @@ HRESULT CordbProcess::GetRuntimeOffsets()
             m_runtimeOffsets.m_signalHijackCompleteBPAddr,
             m_runtimeOffsets.m_excepNotForRuntimeBPAddr,
             m_runtimeOffsets.m_notifyRSOfSyncCompleteBPAddr,
+            m_runtimeOffsets.m_setThreadContextNeededAddr,
         };
 
         const int NumFlares = ARRAY_SIZE(flares);
@@ -11152,7 +11155,162 @@ void CordbProcess::FilterClrNotification(
     }
 }
 
+#ifdef OUT_OF_PROCESS_SETTHREADCONTEXT
+void CordbProcess::HandleSetThreadContextNeeded(DWORD dwThreadId)
+{
+    LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded\n"));
+
+#if defined(TARGET_WINDOWS) && defined(TARGET_AMD64)
+    HandleHolder hThread = OpenThread(
+        THREAD_GET_CONTEXT | THREAD_SET_CONTEXT | THREAD_QUERY_INFORMATION | THREAD_SUSPEND_RESUME,
+        FALSE, // thread handle is not inheritable.
+        dwThreadId);
+
+    if (hThread == NULL)
+    {
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Unexpected result from OpenThread\n"));
+        ThrowHR(E_UNEXPECTED);
+    }
+
+    DWORD previousSuspendCount = ::SuspendThread(hThread);
+    if (previousSuspendCount == (DWORD)-1)
+    {
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Unexpected result from SuspendThread\n"));
+        ThrowHR(HRESULT_FROM_GetLastError());
+    }
+
+    CONTEXT context = { 0 };
+    context.ContextFlags = CONTEXT_FULL;
+
+    HRESULT hr = GetDataTarget()->GetThreadContext(dwThreadId, CONTEXT_FULL, sizeof(CONTEXT), reinterpret_cast<BYTE*> (&context));
+    IfFailThrow(hr);
+
+    TADDR lsContextAddr = (TADDR)context.Rcx;
+    DWORD contextSize = (DWORD)context.Rdx;
+
+    TADDR expectedRip = (TADDR)context.R8;
+    TADDR expectedRsp = (TADDR)context.R9;
+
+    if (contextSize == 0 || contextSize > sizeof(CONTEXT) + 25000)
+    {
+        _ASSERTE(!"Corrupted HandleSetThreadContextNeeded message received");
+
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Corrupted HandleSetThreadContextNeeded message received\n"));
+
+        ThrowHR(E_UNEXPECTED);
+    }
+
+    PCONTEXT pContext = (PCONTEXT)_alloca(contextSize);
+    ULONG32 cbRead;
+    hr = GetDataTarget()->ReadVirtual(lsContextAddr, reinterpret_cast<BYTE*>(pContext), contextSize, &cbRead);
+    if (FAILED(hr))
+    {
+        _ASSERTE(!"ReadVirtual failed");
+
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - ReadVirtual (error: 0x%X).\n", hr));
+
+        ThrowHR(CORDBG_E_READVIRTUAL_FAILURE);
+    }
+
+    if (cbRead != contextSize)
+    {
+        _ASSERTE(!"ReadVirtual context size mismatch");
 
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - ReadVirtual context size mismatch\n"));
+
+        ThrowHR(ERROR_PARTIAL_COPY);
+    }
+
+    if (pContext->Rip != expectedRip || pContext->Rsp != expectedRsp)
+    {
+        _ASSERTE(!"ReadVirtual unexpectedly returned mismatched Rip and Rsp registers");
+
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - ReadVirtual unexpectedly returned mismatched Rip and Rsp registers\n"));
+
+        ThrowHR(E_UNEXPECTED);
+    }
+
+    // TODO: Ideally we would use ICorDebugMutableDataTarget::SetThreadContext however this API currently only handles the legacy context.
+    // We should combine the following code with the shared implementation
+
+    // The initialize call should fail but return contextSize
+    contextSize = 0;
+    DWORD contextFlags = pContext->ContextFlags;
+    BOOL success = InitializeContext(NULL, contextFlags, NULL, &contextSize);
+
+    if(success || GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+    {
+        _ASSERTE(!"InitializeContext unexpectedly succeeded or didn't return ERROR_INSUFFICIENT_BUFFER");
+
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - InitializeContext unexpectedly succeeded or didn't return ERROR_INSUFFICIENT_BUFFER\n"));
+
+        ThrowHR(E_UNEXPECTED);
+    }
+
+    LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - InitializeContext ContextSize %d\n", contextSize));
+
+    PVOID pBuffer = _alloca(contextSize);
+    PCONTEXT pFrameContext = NULL;
+    success = InitializeContext(pBuffer, contextFlags, &pFrameContext, &contextSize);
+    if (!success)
+    {
+        HRESULT hr = HRESULT_FROM_WIN32(GetLastError());
+        _ASSERTE(!"InitializeContext failed");
+
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Unexpected result from InitializeContext (error: 0x%X [%d]).\n", hr, GetLastError()));
+
+        ThrowHR(hr);
+    }
+
+    _ASSERTE((BYTE*)pFrameContext == pBuffer);
+
+    success = CopyContext(pFrameContext, contextFlags, pContext);
+    LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - CopyContext=%s %d\n", success?"SUCCESS":"FAIL", GetLastError()));
+    if (!success)
+    {
+        HRESULT hr = HRESULT_FROM_WIN32(GetLastError());
+        _ASSERTE(!"CopyContext failed");
+
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Unexpected result from CopyContext (error: 0x%X [%d]).\n", hr, GetLastError()));
+
+        ThrowHR(hr);
+    }
+
+    LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Set Thread Context - ID = 0x%X, SS enabled = %d\n", dwThreadId,  /*(uint64_t)hThread,*/ (pContext->EFlags & 0x100) != 0));
+
+    DWORD lastError = 0;
+
+    success = ::SetThreadContext(hThread, pFrameContext);
+    if (!success)
+    {
+        lastError = ::GetLastError();
+    }
+
+    LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Set Thread Context Completed: Success=%d GetLastError=%d hr=0x%X\n", success, lastError, HRESULT_FROM_WIN32(lastError)));
+    _ASSERTE(success);
+
+    DWORD suspendCount = ::ResumeThread(hThread);
+    if (suspendCount == (DWORD)-1)
+    {
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Unexpected result from ResumeThread\n"));
+        ThrowHR(HRESULT_FROM_GetLastError());
+    }
+    if (suspendCount != previousSuspendCount + 1)
+    {
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Unexpected result from ResumeThread\n"));
+        ThrowHR(E_UNEXPECTED);
+    }
+
+    if (!success)
+    {
+        LOG((LF_CORDB, LL_INFO10000, "RS HandleSetThreadContextNeeded - Unexpected result from SetThreadContext\n"));
+        ThrowHR(HRESULT_FROM_WIN32(lastError));
+    }
+#else
+    #error Platform not supported
+#endif
+}
+#endif // OUT_OF_PROCESS_SETTHREADCONTEXT
 
 //
 // If the thread has an unhandled managed exception, hijack it.
@@ -11377,7 +11535,15 @@ HRESULT CordbProcess::Filter(
 
             // holder will invoke DeleteIPCEventHelper(pManagedEvent).
         }
+#ifdef OUT_OF_PROCESS_SETTHREADCONTEXT
+        else if (dwFirstChance && pRecord->ExceptionCode == STATUS_BREAKPOINT && pRecord->ExceptionAddress == m_runtimeOffsets.m_setThreadContextNeededAddr)
+        {
+            // this is a request to set the thread context out of process
 
+            HandleSetThreadContextNeeded(dwThreadId);
+            *pContinueStatus = DBG_CONTINUE;
+        }
+#endif
     }
     PUBLIC_API_END(hr);
     // we may not find the correct mscordacwks so fail gracefully

src/coreclr/debug/di/rspriv.h

@@ -3280,6 +3280,10 @@ class CordbProcess :
 #endif
     }
 
+#ifdef OUT_OF_PROCESS_SETTHREADCONTEXT
+    void HandleSetThreadContextNeeded(DWORD dwThreadId);
+#endif
+
     //
     // Shim  callbacks to simulate fake attach events.
     //

src/coreclr/debug/ee/amd64/dbghelpers.asm

@@ -157,7 +157,13 @@ LEAF_ENTRY NotifyRightSideOfSyncCompleteFlare, _TEXT
         ret
 LEAF_END NotifyRightSideOfSyncCompleteFlare, _TEXT
 
-
+; Flare for setting the context out of process
+LEAF_ENTRY SetThreadContextNeededFlare, _TEXT
+        int 3
+        ; make sure that the basic block is unique
+        test rax,7
+        ret
+LEAF_END SetThreadContextNeededFlare, _TEXT
 
 ; This goes at the end of the assembly file
 	end