Index: sys/cddl/dev/fbt/fbt.c
===================================================================
--- sys/cddl/dev/fbt/fbt.c
+++ sys/cddl/dev/fbt/fbt.c
@@ -171,6 +171,13 @@
 		return (1);
 #endif
 
+#if defined(__riscv)
+	if (strncmp(name, "cpu_exception", 13) == 0)
+		return (1);
+	if (strcmp(name, "do_trap_supervisor") == 0)
+		return (1);
+#endif
+
 	/*
 	 * When DTrace is built into the kernel we need to exclude
 	 * the FBT functions from instrumentation.