thermosphere: add some basic sysreg trapping code

thermosphere/src/synchronization.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2019 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+static inline void __dsb_sy(void)
+{
+    __asm__ __volatile__ ("dsb sy" ::: "memory");
+}
+
+static inline void __isb(void)
+{
+    __asm__ __volatile__ ("isb" ::: "memory");
+}