[Release/8.0] Remove preventing EH and entering EE at shutdown

Backport of #100293 to release/8.0

src/coreclr/vm/ceemain.cpp

@@ -1328,12 +1328,6 @@ void STDMETHODCALLTYPE EEShutDownHelper(BOOL fIsDllUnloading)
             {
                 g_fEEShutDown |= ShutDown_Phase2;
 
-                // Shutdown finalizer before we suspend all background threads. Otherwise we
-                // never get to finalize anything.
-
-                // No longer process exceptions
-                g_fNoExceptions = true;
-
                 // <TODO>@TODO: This does things which shouldn't occur in part 2.  Namely,
                 // calling managed dll main callbacks (AppDomain::SignalProcessDetach), and
                 // RemoveAppDomainFromIPC.
@@ -1350,32 +1344,9 @@ void STDMETHODCALLTYPE EEShutDownHelper(BOOL fIsDllUnloading)
                 TerminateDebugger();
 #endif // DEBUGGING_SUPPORTED
 
-                StubManager::TerminateStubManagers();
-
-#ifdef FEATURE_INTERPRETER
-                Interpreter::Terminate();
-#endif // FEATURE_INTERPRETER
-
                 //@TODO: find the right place for this
                 VirtualCallStubManager::UninitStatic();
 
-                // Unregister our vectored exception and continue handlers from the OS.
-                // This will ensure that if any other DLL unload (after ours) has an exception,
-                // we wont attempt to process that exception (which could lead to various
-                // issues including AV in the runtime).
-                //
-                // This should be done:
-                //
-                // 1) As the last action during the shutdown so that any unexpected AVs
-                //    in the runtime during shutdown do result in FailFast in VEH.
-                //
-                // 2) Only when the runtime is processing DLL_PROCESS_DETACH.
-                CLRRemoveVectoredHandlers();
-
-#if USE_DISASSEMBLER
-                Disassembler::StaticClose();
-#endif // USE_DISASSEMBLER
-
                 WriteJitHelperCountToSTRESSLOG();
 
                 STRESS_LOG0(LF_STARTUP, LL_INFO10, "EEShutdown shutting down logging");
@@ -1699,10 +1670,6 @@ BOOL STDMETHODCALLTYPE EEDllMain( // TRUE on success, FALSE on error.
                     LOG((LF_STARTUP, INFO3, "EEShutDown invoked from EEDllMain"));
                     EEShutDown(TRUE); // shut down EE if it was started up
                 }
-                else
-                {
-                    CLRRemoveVectoredHandlers();
-                }
                 break;
             }
         }

src/coreclr/vm/crst.h

@@ -103,7 +103,6 @@ extern DWORD g_fEEShutDown;
 #endif
 // Total count of Crst lock  of the type (Shutdown) that are currently in use
 extern Volatile<LONG> g_ShutdownCrstUsageCount;
-extern Volatile<LONG> g_fForbidEnterEE;
 
 // The CRST.
 class CrstBase

src/coreclr/vm/eehash.inl

@@ -346,7 +346,7 @@ BOOL EEHashTableBase<KeyType, Helper, bDefaultCopyIsDeep>::DeleteValue(KeyType p
     _ASSERTE (OwnLock());
 
     Thread *pThread = GetThreadNULLOk();
-    GCX_MAYBE_COOP_NO_THREAD_BROKEN(pThread ? !(pThread->m_StateNC & Thread::TSNC_UnsafeSkipEnterCooperative) : FALSE);
+    GCX_MAYBE_COOP_NO_THREAD_BROKEN(pThread != NULL);
 
     _ASSERTE(m_pVolatileBucketTable->m_dwNumBuckets != 0);
 
@@ -850,7 +850,7 @@ BOOL EEHashTableBase<KeyType, Helper, bDefaultCopyIsDeep>::
     _ASSERTE_IMPL(OwnLock());
 
     Thread *pThread = GetThreadNULLOk();
-    GCX_MAYBE_COOP_NO_THREAD_BROKEN(pThread ? !(pThread->m_StateNC & Thread::TSNC_UnsafeSkipEnterCooperative) : FALSE);
+    GCX_MAYBE_COOP_NO_THREAD_BROKEN(pThread != NULL);
 
     _ASSERTE(pIter->m_pTable == (void *) this);
 

src/coreclr/vm/eepolicy.cpp

@@ -41,8 +41,6 @@ void SafeExitProcess(UINT exitCode, ShutdownCompleteAction sca = SCA_ExitProcess
     // other DLLs call Release() on us in their detach [dangerous!], etc.
     GCX_PREEMP_NO_DTOR();
 
-    InterlockedExchange((LONG*)&g_fForbidEnterEE, TRUE);
-
     // Note that for free and retail builds StressLog must also be enabled
     if (g_pConfig && g_pConfig->StressLog())
     {
@@ -59,13 +57,6 @@ void SafeExitProcess(UINT exitCode, ShutdownCompleteAction sca = SCA_ExitProcess
         }
     }
 
-    // Turn off exception processing, because if some other random DLL has a
-    //  fault in DLL_PROCESS_DETACH, we could get called for exception handling.
-    //  Since we've turned off part of the runtime, we can't, for instance,
-    //  properly execute the GC that handling an exception might trigger.
-    g_fNoExceptions = true;
-    LOG((LF_EH, LL_INFO10, "SafeExitProcess: turning off exceptions\n"));
-
     if (sca == SCA_TerminateProcessWhenShutdownComplete)
     {
         // disabled because if we fault in this code path we will trigger our Watson code

src/coreclr/vm/excep.cpp

@@ -4585,13 +4585,6 @@ LONG InternalUnhandledExceptionFilter_Worker(
     STRESS_LOG2(LF_EH, LL_INFO10, "In InternalUnhandledExceptionFilter_Worker, Exception = %x, sp = %p\n",
                                     pExceptionInfo->ExceptionRecord->ExceptionCode, GetCurrentSP());
 
-    // If we can't enter the EE, done.
-    if (g_fForbidEnterEE)
-    {
-        LOG((LF_EH, LL_INFO100, "InternalUnhandledExceptionFilter_Worker: g_fForbidEnterEE is TRUE\n"));
-        return EXCEPTION_CONTINUE_SEARCH;
-    }
-
     // We don't do anything when this is called from an unmanaged thread.
     Thread *pThread = GetThreadNULLOk();
 
@@ -4623,18 +4616,6 @@ LONG InternalUnhandledExceptionFilter_Worker(
     }
 #endif
 
-    // This shouldn't be possible, but MSVC re-installs us... for now, just bail if this happens.
-    if (g_fNoExceptions)
-    {
-        return EXCEPTION_CONTINUE_SEARCH;
-    }
-
-    // Are we looking at a stack overflow here?
-    if ((pThread !=  NULL) && !pThread->DetermineIfGuardPagePresent())
-    {
-        g_fForbidEnterEE = true;
-    }
-
 #ifdef DEBUGGING_SUPPORTED
 
     // Mark that this exception has gone unhandled. At the moment only the debugger will
@@ -5533,8 +5514,6 @@ static LONG ThreadBaseExceptionFilter_Worker(PEXCEPTION_POINTERS pExceptionInfo,
     ThreadBaseExceptionFilterParam *pParam = (ThreadBaseExceptionFilterParam *) pvParam;
     UnhandledExceptionLocation location = pParam->location;
 
-    _ASSERTE(!g_fNoExceptions);
-
     Thread* pThread = GetThread();
 
 #ifdef _DEBUG
@@ -6704,14 +6683,6 @@ VEH_ACTION WINAPI CLRVectoredExceptionHandlerPhase3(PEXCEPTION_POINTERS pExcepti
 
 VEH_ACTION WINAPI CLRVectoredExceptionHandler(PEXCEPTION_POINTERS pExceptionInfo)
 {
-    // It is not safe to execute code inside VM after we shutdown EE.  One example is DisablePreemptiveGC
-    // will block forever.
-    if (g_fForbidEnterEE)
-    {
-        return VEH_CONTINUE_SEARCH;
-    }
-
-
     //
     // DO NOT USE CONTRACTS HERE AS THIS ROUTINE MAY NEVER RETURN.  You can use
     // static contracts, but currently this is all WRAPPER_NO_CONTRACT.
@@ -7393,12 +7364,6 @@ LONG WINAPI CLRVectoredExceptionHandlerShim(PEXCEPTION_POINTERS pExceptionInfo)
     // WARNING WARNING WARNING WARNING WARNING WARNING WARNING
     //
 
-    // If exceptions (or runtime) have been disabled, then simply return.
-    if (g_fForbidEnterEE || g_fNoExceptions)
-    {
-        return EXCEPTION_CONTINUE_SEARCH;
-    }
-
     // WARNING
     //
     // We must preserve this so that GCStress=4 eh processing doesnt kill last error.
@@ -7636,35 +7601,6 @@ void CLRAddVectoredHandlers(void)
 #endif // !TARGET_UNIX
 }
 
-// This function removes the vectored exception and continue handler registration
-// from the OS.
-void CLRRemoveVectoredHandlers(void)
-{
-    CONTRACTL
-    {
-        NOTHROW;
-        GC_NOTRIGGER;
-        MODE_ANY;
-    }
-    CONTRACTL_END;
-#ifndef TARGET_UNIX
-
-    // Unregister the vectored exception handler if one is registered (and we can).
-    if (g_hVectoredExceptionHandler != NULL)
-    {
-        // Unregister the vectored exception handler
-        if (RemoveVectoredExceptionHandler(g_hVectoredExceptionHandler) == FALSE)
-        {
-            LOG((LF_EH, LL_INFO100, "CLRRemoveVectoredHandlers: RemoveVectoredExceptionHandler() failed.\n"));
-        }
-        else
-        {
-            LOG((LF_EH, LL_INFO100, "CLRRemoveVectoredHandlers: RemoveVectoredExceptionHandler() succeeded.\n"));
-        }
-    }
-#endif // !TARGET_UNIX
-}
-
 //
 // This does the work of the Unwind and Continue Hanlder inside the catch clause of that handler. The stack has not
 // been unwound when this is called. Keep that in mind when deciding where to put new code :)

src/coreclr/vm/excep.h

@@ -100,7 +100,6 @@ struct EE_ILEXCEPTION_CLAUSE;
 
 void InitializeExceptionHandling();
 void CLRAddVectoredHandlers(void);
-void CLRRemoveVectoredHandlers(void);
 void TerminateExceptionHandling();
 
 // Prototypes

src/coreclr/vm/i386/excepx86.cpp

@@ -1571,9 +1571,6 @@ EXCEPTION_HANDLER_IMPL(COMPlusFrameHandler)
 
     _ASSERTE((pContext == NULL) || ((pContext->ContextFlags & CONTEXT_CONTROL) == CONTEXT_CONTROL));
 
-    if (g_fNoExceptions)
-        return ExceptionContinueSearch; // No EH during EE shutdown.
-
     // Check if the exception represents a GCStress Marker. If it does,
     // we shouldnt record its entry in the TLS as such exceptions are
     // continuable and can confuse the VM to treat them as CSE,

src/coreclr/vm/runtimecallablewrapper.cpp

@@ -1233,16 +1233,6 @@ HRESULT RCWCleanupList::ReleaseRCWListInCorrectCtx(LPVOID pData)
 
     LPVOID pCurrCtxCookie = GetCurrentCtxCookie();
 
-    // If we are releasing our IP's as a result of shutdown, we MUST not transition
-    // into cooperative GC mode. This "fix" will prevent us from doing so.
-    if (g_fEEShutDown & ShutDown_Finalize2)
-    {
-        Thread *pThread = GetThreadNULLOk();
-        if (pThread && !FinalizerThread::IsCurrentThreadFinalizer())
-            pThread->SetThreadStateNC(Thread::TSNC_UnsafeSkipEnterCooperative);
-    }
-
-
     // Make sure we're in the right context / apartment.
     // Also - if we've already transitioned once, we don't want to do so again.
     //  If the cookie exists in multiple MTA apartments, and the STA has gone away
@@ -1274,14 +1264,6 @@ HRESULT RCWCleanupList::ReleaseRCWListInCorrectCtx(LPVOID pData)
         }
     }
 
-    // Reset the bit indicating we cannot transition into cooperative GC mode.
-    if (g_fEEShutDown & ShutDown_Finalize2)
-    {
-        Thread *pThread = GetThreadNULLOk();
-        if (pThread && !FinalizerThread::IsCurrentThreadFinalizer())
-            pThread->ResetThreadStateNC(Thread::TSNC_UnsafeSkipEnterCooperative);
-    }
-
     return S_OK;
 }
 
@@ -1565,7 +1547,6 @@ void RCW::RemoveMemoryPressure()
         NOTHROW;
         GC_TRIGGERS;
         MODE_PREEMPTIVE;
-        PRECONDITION((GetThread()->m_StateNC & Thread::TSNC_UnsafeSkipEnterCooperative) == 0);
     }
     CONTRACTL_END;
 
@@ -1777,7 +1758,6 @@ void RCW::Cleanup()
     // if the wrapper is still in the cache.  Also, if we can't switch to coop mode,
     // we're guaranteed to have already decoupled the RCW from its object.
 #ifdef _DEBUG
-    if (!(GetThread()->m_StateNC & Thread::TSNC_UnsafeSkipEnterCooperative))
     {
         GCX_COOP();
 
@@ -1795,9 +1775,7 @@ void RCW::Cleanup()
         ReleaseAllInterfacesCallBack(this);
 
         // Remove the memory pressure caused by this RCW (if present)
-        // If we're in a shutdown situation, we can ignore the memory pressure.
-        if ((GetThread()->m_StateNC & Thread::TSNC_UnsafeSkipEnterCooperative) == 0 && !g_fForbidEnterEE)
-            RemoveMemoryPressure();
+        RemoveMemoryPressure();
     }
 
 #ifdef _DEBUG