kernel/thread: Fix potential crashes introduced in 3bcf090d37

This amends cases where crashes can occur that were missed due to the
odd way the previous code was set up (using 3DS memory regions that
don't exist).

src/core/hle/kernel/thread.cpp

@@ -339,6 +339,17 @@ ResultVal<SharedPtr<Thread>> Thread::Create(std::string name, VAddr entry_point,
         tls_slots.emplace_back(0); // The page is completely available at the start
         available_page = tls_slots.size() - 1;
         available_slot = 0; // Use the first slot in the new page
+
+        // Allocate some memory from the end of the linear heap for this region.
+        const size_t offset = thread->tls_memory->size();
+        thread->tls_memory->insert(thread->tls_memory->end(), Memory::PAGE_SIZE, 0);
+
+        auto& vm_manager = owner_process->vm_manager;
+        vm_manager.RefreshMemoryBlockMappings(thread->tls_memory.get());
+
+        vm_manager.MapMemoryBlock(Memory::TLS_AREA_VADDR + available_page * Memory::PAGE_SIZE,
+                                  thread->tls_memory, 0, Memory::PAGE_SIZE,
+                                  MemoryState::ThreadLocal);
     }
 
     // Mark the slot as used