Index: sys/arm64/arm64/trap.c
===================================================================
--- sys/arm64/arm64/trap.c
+++ sys/arm64/arm64/trap.c
@@ -39,6 +39,7 @@
 #include <sys/proc.h>
 #include <sys/ptrace.h>
 #include <sys/syscall.h>
+#include <sys/sysctl.h>
 #include <sys/sysent.h>
 #ifdef KDB
 #include <sys/kdb.h>
@@ -74,6 +75,12 @@
 #include <ddb/db_sym.h>
 #endif
 
+static int uprintf_signal;
+SYSCTL_INT(_machdep, OID_AUTO, uprintf_signal, CTLFLAG_RWTUN,
+    &uprintf_signal, 0,
+    "Print debugging information on trap signal to ctty");
+
+
 /* Called from exception.S */
 void do_el1h_sync(struct thread *, struct trapframe *);
 void do_el0_sync(struct thread *, struct trapframe *);
@@ -120,6 +127,8 @@
 static __inline void
 call_trapsignal(struct thread *td, int sig, int code, void *addr, int trapno)
 {
+	struct proc *p;
+	struct trapframe *frame;
 	ksiginfo_t ksi;
 
 	ksiginfo_init_trap(&ksi);
@@ -127,6 +136,15 @@
 	ksi.ksi_code = code;
 	ksi.ksi_addr = addr;
 	ksi.ksi_trapno = trapno;
+
+	if (uprintf_signal) {
+		p = td->td_proc;
+		frame = td->td_frame;
+
+		uprintf("pid %d comm %s: signal %d code %d type %d addr %p\n",
+		    p->p_pid, p->p_comm, sig, code, trapno, addr);
+		print_registers(frame);
+	}
 	trapsignal(td, &ksi);
 }