Revert "Fix exception propagation over HW exception frame on macOS arm64 (dotnet#63482)"

This reverts commit 897694f.

Author: jkotas

src/coreclr/pal/src/exception/machexception.cpp

@@ -376,8 +376,6 @@ void PAL_DispatchException(PCONTEXT pContext, PEXCEPTION_RECORD pExRecord, MachE
     *contextRecord = *pContext;
     *exceptionRecord = *pExRecord;
 
-    g_hardware_exception_context_locvar_offset = (int)((char*)&contextRecord - (char*)__builtin_frame_address(0));
-
     contextRecord->ContextFlags |= CONTEXT_EXCEPTION_ACTIVE;
     bool continueExecution;
 

src/coreclr/pal/src/exception/seh-unwind.cpp

@@ -496,9 +496,7 @@ void GetContextPointers(unw_cursor_t *cursor, unw_context_t *unwContext, KNONVOL
 
 #ifndef HOST_WINDOWS
 
-// Frame pointer relative offset of a local containing a pointer to the windows style context of a location
-// where a hardware exception occured.
-int g_hardware_exception_context_locvar_offset = 0;
+extern int g_common_signal_handler_context_locvar_offset;
 
 BOOL PAL_VirtualUnwind(CONTEXT *context, KNONVOLATILE_CONTEXT_POINTERS *contextPointers)
 {
@@ -508,17 +506,19 @@ BOOL PAL_VirtualUnwind(CONTEXT *context, KNONVOLATILE_CONTEXT_POINTERS *contextP
 
     DWORD64 curPc = CONTEXTGetPC(context);
 
-    // Check if the PC is the return address from the SEHProcessException.
-    // If that's the case, extract its local variable containing a pointer to the windows style context of the hardware
+#ifndef __APPLE__
+    // Check if the PC is the return address from the SEHProcessException in the common_signal_handler.
+    // If that's the case, extract its local variable containing the windows style context of the hardware
     // exception and return that. This skips the hardware signal handler trampoline that the libunwind
-    // cannot cross on some systems. On macOS, it skips a similar trampoline we create in HijackFaultingThread.
+    // cannot cross on some systems.
     if ((void*)curPc == g_SEHProcessExceptionReturnAddress)
     {
-        CONTEXT* exceptionContext = *(CONTEXT**)(CONTEXTGetFP(context) + g_hardware_exception_context_locvar_offset);
-        memcpy_s(context, sizeof(CONTEXT), exceptionContext, sizeof(CONTEXT));
+        CONTEXT* signalContext = (CONTEXT*)(CONTEXTGetFP(context) + g_common_signal_handler_context_locvar_offset);
+        memcpy_s(context, sizeof(CONTEXT), signalContext, sizeof(CONTEXT));
 
         return TRUE;
     }
+#endif
 
     if ((context->ContextFlags & CONTEXT_EXCEPTION_ACTIVE) != 0)
     {

src/coreclr/pal/src/exception/signal.cpp

@@ -116,6 +116,10 @@ struct sigaction g_previous_sigabrt;
 
 #if !HAVE_MACH_EXCEPTIONS
 
+// Offset of the local variable containing pointer to windows style context in the common_signal_handler function.
+// This offset is relative to the frame pointer.
+int g_common_signal_handler_context_locvar_offset = 0;
+
 // TOP of special stack for handling stack overflow
 volatile void* g_stackOverflowHandlerStack = NULL;
 
@@ -935,12 +939,11 @@ static bool common_signal_handler(int code, siginfo_t *siginfo, void *sigcontext
 #if !HAVE_MACH_EXCEPTIONS
     sigset_t signal_set;
     CONTEXT signalContextRecord;
-    CONTEXT* signalContextRecordPtr = &signalContextRecord;
     EXCEPTION_RECORD exceptionRecord;
     native_context_t *ucontext;
 
     ucontext = (native_context_t *)sigcontext;
-    g_hardware_exception_context_locvar_offset = (int)((char*)&signalContextRecordPtr - (char*)__builtin_frame_address(0));
+    g_common_signal_handler_context_locvar_offset = (int)((char*)&signalContextRecord - (char*)__builtin_frame_address(0));
 
     if (code == (SIGSEGV | StackOverflowFlag))
     {

src/coreclr/pal/src/include/pal/seh.hpp

@@ -145,10 +145,5 @@ CorUnix::PAL_ERROR SEHDisable(CorUnix::CPalThread *pthrCurrent);
 
 }
 
-// Offset of the local variable containing pointer to windows style context in the common_signal_handler / PAL_DispatchException function.
-// This offset is relative to the frame pointer.
-extern int g_hardware_exception_context_locvar_offset;
-
-
 #endif /* _PAL_SEH_HPP_ */