Index: sys/cddl/dev/fbt/fbt.c
===================================================================
--- sys/cddl/dev/fbt/fbt.c
+++ sys/cddl/dev/fbt/fbt.c
@@ -171,6 +171,21 @@
 		return (1);
 #endif
 
+#if defined(__riscv)
+	/*
+	 * Some assembly-language exception handlers are not suitable for
+	 * instrumentation.
+	 */
+	if (strcmp(name, "cpu_exception_handler") == 0)
+		return (1);
+	if (strcmp(name, "cpu_exception_handler_user") == 0)
+		return (1);
+	if (strcmp(name, "cpu_exception_handler_supervisor") == 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.