Kernel: Reintroduce `ScopedAddressSpaceSwitcher` to aarch64 build

Kernel/CMakeLists.txt

@@ -532,6 +532,7 @@ else()
         Memory/RegionTree.cpp
         Memory/RingBuffer.cpp
         Memory/ScatterGatherList.cpp
+        Memory/ScopedAddressSpaceSwitcher.cpp
         Memory/SharedInodeVMObject.cpp
         Memory/VirtualRange.cpp
         Memory/VMObject.cpp

Kernel/Memory/ScopedAddressSpaceSwitcher.cpp

@@ -13,15 +13,23 @@ namespace Kernel {
 ScopedAddressSpaceSwitcher::ScopedAddressSpaceSwitcher(Process& process)
 {
     VERIFY(Thread::current() != nullptr);
+#if ARCH(I386) || ARCH(X86_64)
     m_previous_cr3 = read_cr3();
+#elif ARCH(AARC64)
+    TODO_AARCH64();
+#endif
     Memory::MemoryManager::enter_process_address_space(process);
 }
 
 ScopedAddressSpaceSwitcher::~ScopedAddressSpaceSwitcher()
 {
     InterruptDisabler disabler;
+#if ARCH(I386) || ARCH(X86_64)
     Thread::current()->regs().cr3 = m_previous_cr3;
     write_cr3(m_previous_cr3);
+#elif ARCH(AARC64)
+    TODO_AARCH64();
+#endif
 }
 
 }