kernel: add common functions for user mode Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

diff --git a/kernel/thread.c b/kernel/thread.c
index f298e1a..1bfdf7e 100644
--- a/kernel/thread.c
+++ b/kernel/thread.c

@@ -500,3 +500,13 @@
 	thread_data->init_groups &= groups;
 }
 
+
+#ifdef CONFIG_USERSPACE
+FUNC_NORETURN void k_thread_user_mode_enter(k_thread_entry_t entry,
+					    void *p1, void *p2, void *p3)
+{
+	_current->base.user_options |= K_USER;
+	_thread_essential_clear();
+	_arch_user_mode_enter(entry, p1, p2, p3);
+}
+#endif /* CONFIG_USERSPACE */