Fix SSP issue with HW exceptions from JIT helpers (dotnet#107665)

The recent change that was fixing bad SSP updating during exception
handling with funceval has also modified the way SSP is extracted for
hardware exceptions. That works fine for many cases, but there is a
problem when the exception occurs in a JIT helper. The
`AjustContextForJITHelpers` uses only the basic `CONTEXT` structure for
unwinding to the managed caller and so the SSP is not properly updated.
That makes it off by one slot when we set it when continuing execution
after catch.
This change removes storing SSP for hardware exceptions in the
FaultingExceptionFrame to mitigate the issue. It effectively returns to
the way software exceptions use - scanning shadow stack for the
instruction pointer of the frame to which it is going to resume after
catch.

Co-authored-by: Jan Vorlicek <jan.vorlicek@volny,cz>

src/coreclr/vm/amd64/RedirectedHandledJITCase.asm

@@ -144,7 +144,7 @@ STUB&_RspAligned:
 
         mov             dword ptr [rcx], 0                                                          ; Initialize vtbl (it is not strictly necessary)
         mov             dword ptr [rcx + OFFSETOF__FaultingExceptionFrame__m_fFilterExecuted], 0    ; Initialize BOOL for personality routine
-        mov             qword ptr [rcx + OFFSETOF__FaultingExceptionFrame__m_SSP], rax
+        mov             r8, rax
 
         call            TARGET
 
@@ -185,6 +185,7 @@ NESTED_ENTRY RedirectForThrowControl2, _TEXT
 
         save_reg_postrsp    rcx, REDIRECT_FOR_THROW_CONTROL_FRAME_SIZE + 8h     ; FaultingExceptionFrame
         save_reg_postrsp    rdx, REDIRECT_FOR_THROW_CONTROL_FRAME_SIZE + 10h    ; Original RSP
+        save_reg_postrsp    r8, REDIRECT_FOR_THROW_CONTROL_FRAME_SIZE + 18h     ; SSP
 
         END_PROLOGUE
 
@@ -197,7 +198,8 @@ NESTED_ENTRY RedirectForThrowControl2, _TEXT
         mov             rdx, [rsp + REDIRECT_FOR_THROW_CONTROL_FRAME_SIZE + 10h] ; Original RSP
         mov             [rdx - 8], rax
 
-        mov             rcx, [rsp + REDIRECT_FOR_THROW_CONTROL_FRAME_SIZE + 8h] ; FaultingExceptionFrame
+        mov             rcx, [rsp + REDIRECT_FOR_THROW_CONTROL_FRAME_SIZE + 8h]  ; FaultingExceptionFrame
+        mov             rdx, [rsp + REDIRECT_FOR_THROW_CONTROL_FRAME_SIZE + 18h] ; SSP
         call            ThrowControlForThread
 
         ; ThrowControlForThread doesn't return.

src/coreclr/vm/excep.cpp

@@ -6279,10 +6279,6 @@ void HandleManagedFaultNew(EXCEPTION_RECORD* pExceptionRecord, CONTEXT* pContext
 #endif // FEATURE_EH_FUNCLETS
     frame->InitAndLink(pContext);
 
-#if defined(TARGET_AMD64) && defined(TARGET_WINDOWS)
-    frame->SetSSP(GetSSP(pContext));
-#endif
-
     Thread *pThread = GetThread();
 
     ExInfo exInfo(pThread, pExceptionRecord, pContext, ExKind::HardwareFault);
@@ -6364,6 +6360,11 @@ void FaultingExceptionFrame::Init(CONTEXT *pContext)
     m_ReturnAddress = ::GetIP(pContext);
     CopyOSContext(&m_ctx, pContext);
 #endif // !FEATURE_EH_FUNCLETS
+
+#if defined(TARGET_AMD64) && defined(TARGET_WINDOWS)
+    m_SSP = 0;
+#endif
+
 }
 
 //

src/coreclr/vm/threads.h

@@ -378,6 +378,9 @@ EXTERN_C void ThrowControlForThread(
 #ifdef FEATURE_EH_FUNCLETS
         FaultingExceptionFrame *pfef
 #endif // FEATURE_EH_FUNCLETS
+#if defined(TARGET_AMD64) && defined(TARGET_WINDOWS)
+        , TADDR ssp
+#endif // TARGET_AMD64 && TARGET_WINDOWS
         );
 
 #if defined(_DEBUG)

src/coreclr/vm/threadsuspend.cpp

@@ -3735,6 +3735,9 @@ ThrowControlForThread(
 #ifdef FEATURE_EH_FUNCLETS
         FaultingExceptionFrame *pfef
 #endif // FEATURE_EH_FUNCLETS
+#if defined(TARGET_AMD64) && defined(TARGET_WINDOWS)
+        , TADDR ssp
+#endif // TARGET_AMD64 && TARGET_WINDOWS
         )
 {
     STATIC_CONTRACT_THROWS;
@@ -3784,6 +3787,10 @@ ThrowControlForThread(
 #endif // FEATURE_EH_FUNCLETS
     pfef->InitAndLink(pThread->m_OSContext);
 
+#if defined(TARGET_AMD64) && defined(TARGET_WINDOWS)
+    pfef->SetSSP(ssp);
+#endif
+
     // !!! Can not assert here.  Sometimes our EHInfo for catch clause extends beyond
     // !!! Jit_EndCatch.  Not sure if we have guarantee on catch clause.
     //_ASSERTE (pThread->ReadyForAbort());