Add initial CoreCLR compilation support for Apple Silicon

src/coreclr/src/pal/src/arch/arm64/context2.S

@@ -111,7 +111,6 @@ LEAF_END CONTEXT_CaptureContext, _TEXT
 
 // Incoming:
 //  x0: Context*
-
 LEAF_ENTRY RtlCaptureContext, _TEXT
     PROLOG_STACK_ALLOC 16
     .cfi_adjust_cfa_offset 16
@@ -129,6 +128,7 @@ LEAF_ENTRY RtlCaptureContext, _TEXT
     b C_FUNC(CONTEXT_CaptureContext)
 LEAF_END RtlCaptureContext, _TEXT
 
+#ifndef HOST_OSX
 // Incoming:
 //  x0: Context*
 //  x1: Exception*
@@ -213,3 +213,4 @@ LOCAL_LABEL(No_Restore_CONTEXT_CONTROL):
    ret
 
 LEAF_END RtlRestoreContext, _TEXT
+#endif // !HOST_OSX

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

@@ -1429,6 +1429,19 @@ ActivationHandler(CONTEXT* context)
     DebugBreak();
 }
 
+#if defined(TARGET_ARM64)
+extern "C"
+void
+RtlRestoreContext(CONTEXT* context, PEXCEPTION_RECORD ExceptionRecord)
+{
+    // RtlRestoreContext assembly corrupts X16 & X17, so it cannot be
+    // used in thread hijacking situations
+    // Since we have the higher fidelity MachSetThreadContext, use it in
+    // all situations
+    MachSetThreadContext(context);
+}
+#endif
+
 extern "C" void ActivationHandlerWrapper();
 extern "C" int ActivationHandlerReturnOffset;
 extern "C" unsigned int XmmYmmStateSupport();
@@ -1489,7 +1502,9 @@ InjectActivationInternal(CPalThread* pThread)
         static const int MaxHardwareExceptionVector = 31;
         if (ExceptionState.__trapno > MaxHardwareExceptionVector)
 #elif defined(HOST_ARM64)
-        // TBD // Inject the activation only if the thread doesn't have a pending hardware exception
+        // Inject the activation only if the last ESR.EC was an SVC and therefore the thread doesn't have
+        // a pending hardware exception
+        if ((ExceptionState.__esr >> 26) == 0x15)
 #else
 #error Unexpected architecture
 #endif

src/coreclr/src/vm/dynamicmethod.cpp

@@ -551,6 +551,10 @@ void HostCodeHeap::AddToFreeList(TrackAllocation *pBlockToInsert)
 
     LOG((LF_BCL, LL_INFO100, "Level2 - CodeHeap [0x%p] - Add to FreeList [%p, 0x%X]\n", this, pBlockToInsert, pBlockToInsert->size));
 
+#if defined(HOST_OSX) && defined(HOST_ARM64)
+    auto jitWriteEnableHolder = PAL_JITWriteEnable(true);
+#endif // defined(HOST_OSX) && defined(HOST_ARM64)
+
     // append to the list in the proper position and coalesce if needed
     if (m_pFreeList)
     {