10 files changed, 117 insertions, 155 deletions

diff --git a/sys/dev/cfe/cfe_console.c b/sys/dev/cfe/cfe_console.c
index 1461ef21119f..f3946c571ecc 100644
--- a/sys/dev/cfe/cfe_console.c
+++ b/sys/dev/cfe/cfe_console.c
@@ -67,7 +67,7 @@ static int			polltime;
 static struct callout_handle	cfe_timeouthandle
     = CALLOUT_HANDLE_INITIALIZER(&cfe_timeouthandle);
 
-#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
+#if defined(KDB)
 static int			alt_break_state;
 #endif
 
@@ -191,24 +191,8 @@ cfe_cngetc(struct consdev *cp)
 	unsigned char ch;
 
 	if (cfe_read(conhandle, &ch, 1) == 1) {
-#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
-		int kdb_brk;
-
-		if ((kdb_brk = kdb_alt_break(ch, &alt_break_state)) != 0) {
-			switch (kdb_brk) {
-			case KDB_REQ_DEBUGGER:
-				kdb_enter(KDB_WHY_BREAK,
-				    "Break sequence on console");
-				break;
-			case KDB_REQ_PANIC:
-				kdb_panic("Panic sequence on console");
-				break;
-			case KDB_REQ_REBOOT:
-				kdb_reboot();
-				break;
-
-			}
-		}
+#if defined(KDB)
+		kdb_alt_break(ch, &alt_break_state);
 #endif
 		return (ch);
 	}
diff --git a/sys/dev/dcons/dcons_os.c b/sys/dev/dcons/dcons_os.c
index 3b98cdd255f7..53ac612f6ba8 100644
--- a/sys/dev/dcons/dcons_os.c
+++ b/sys/dev/dcons/dcons_os.c
@@ -133,38 +133,21 @@ static struct ttydevsw dcons_ttydevsw = {
 	.tsw_outwakeup  = dcons_outwakeup,
 };
 
-#if (defined(GDB) || defined(DDB)) && defined(ALT_BREAK_TO_DEBUGGER)
+#if (defined(GDB) || defined(DDB))
 static int
 dcons_check_break(struct dcons_softc *dc, int c)
 {
-	int kdb_brk;
 
 	if (c < 0)
 		return (c);
 
-	if ((kdb_brk = kdb_alt_break(c, &dc->brk_state)) != 0) {
-		switch (kdb_brk) {
-		case KDB_REQ_DEBUGGER:
-			if ((dc->flags & DC_GDB) != 0) {
 #ifdef GDB
-				if (gdb_cur == &dcons_gdb_dbgport) {
-					kdb_dbbe_select("gdb");
-					kdb_enter(KDB_WHY_BREAK,
-					    "Break sequence on dcons gdb port");
-				}
+	if ((dc->flags & DC_GDB) != 0 && gdb_cur == &dcons_gdb_dbgport)
+		kdb_alt_break_gdb(c, &dc->brk_state);
+	else
 #endif
-			} else
-				kdb_enter(KDB_WHY_BREAK,
-				    "Break sequence on dcons console port");
-			break;
-		case KDB_REQ_PANIC:
-			kdb_panic("Panic sequence on dcons console port");
-			break;
-		case KDB_REQ_REBOOT:
-			kdb_reboot();
-			break;
-		}
-	}
+		kdb_alt_break(c, &dc->brk_state);
+
 	return (c);
 }
 #else
diff --git a/sys/dev/ofw/ofw_console.c b/sys/dev/ofw/ofw_console.c
index fd280c97fc89..b4a949c1f19f 100644
--- a/sys/dev/ofw/ofw_console.c
+++ b/sys/dev/ofw/ofw_console.c
@@ -64,7 +64,7 @@ static int			polltime;
 static struct callout_handle	ofw_timeouthandle
     = CALLOUT_HANDLE_INITIALIZER(&ofw_timeouthandle);
 
-#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
+#if defined(KDB)
 static int			alt_break_state;
 #endif
 
@@ -199,24 +199,8 @@ ofw_cngetc(struct consdev *cp)
 	unsigned char ch;
 
 	if (OF_read(stdin, &ch, 1) > 0) {
-#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
-		int kdb_brk;
-
-		if ((kdb_brk = kdb_alt_break(ch, &alt_break_state)) != 0) {
-			switch (kdb_brk) {
-			case KDB_REQ_DEBUGGER:
-				kdb_enter(KDB_WHY_BREAK,
-				    "Break sequence on console");
-				break;
-			case KDB_REQ_PANIC:
-				kdb_panic("Panic sequence on console");
-				break;
-			case KDB_REQ_REBOOT:
-				kdb_reboot();
-				break;
-
-			}
-		}
+#if defined(KDB)
+		kdb_alt_break(ch, &alt_break_state);
 #endif
 		return (ch);
 	}
diff --git a/sys/dev/sio/sio.c b/sys/dev/sio/sio.c
index f1348c4c3576..1f2590f8918d 100644
--- a/sys/dev/sio/sio.c
+++ b/sys/dev/sio/sio.c
@@ -228,7 +228,7 @@ struct com_s {
 
 	struct	pps_state pps;
 	int	pps_bit;
-#ifdef ALT_BREAK_TO_DEBUGGER
+#ifdef KDB
 	int	alt_brk_state;
 #endif
 
@@ -1102,8 +1102,7 @@ determined_type: ;
 		}
 		if (ret)
 			device_printf(dev, "could not activate interrupt\n");
-#if defined(KDB) && (defined(BREAK_TO_DEBUGGER) || \
-    defined(ALT_BREAK_TO_DEBUGGER))
+#if defined(KDB)
 		/*
 		 * Enable interrupts for early break-to-debugger support
 		 * on the console.
@@ -1196,8 +1195,7 @@ comclose(tp)
 	com->poll_output = FALSE;
 	sio_setreg(com, com_cfcr, com->cfcr_image &= ~CFCR_SBREAK);
 
-#if defined(KDB) && (defined(BREAK_TO_DEBUGGER) || \
-    defined(ALT_BREAK_TO_DEBUGGER))
+#if defined(KDB)
 	/*
 	 * Leave interrupts enabled and don't clear DTR if this is the
 	 * console. This allows us to detect break-to-debugger events
@@ -1483,9 +1481,8 @@ siointr1(com)
 	u_char	modem_status;
 	u_char	*ioptr;
 	u_char	recv_data;
-#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
-	int	kdb_brk;
 
+#ifdef KDB
 again:
 #endif
 
@@ -1518,27 +1515,9 @@ again:
 			else
 				recv_data = inb(com->data_port);
 #ifdef KDB
-#ifdef ALT_BREAK_TO_DEBUGGER
 			if (com->unit == comconsole &&
-			    (kdb_brk = kdb_alt_break(recv_data,
-					&com->alt_brk_state)) != 0) {
-				mtx_unlock_spin(&sio_lock);
-				switch (kdb_brk) {
-				case KDB_REQ_DEBUGGER:
-					kdb_enter(KDB_WHY_BREAK,
-					    "Break sequence on console");
-					break;
-				case KDB_REQ_PANIC:
-					kdb_panic("panic on console");
-					break;
-				case KDB_REQ_REBOOT:
-					kdb_reboot();
-					break;
-				}
-				mtx_lock_spin(&sio_lock);
+			    kdb_alt_break(recv_data, &com->alt_brk_state) != 0)
 				goto again;
-			}
-#endif /* ALT_BREAK_TO_DEBUGGER */
 #endif /* KDB */
 			if (line_status & (LSR_BI | LSR_FE | LSR_PE)) {
 				/*
@@ -1554,10 +1533,9 @@ again:
 				 * Note: BI together with FE/PE means just BI.
 				 */
 				if (line_status & LSR_BI) {
-#if defined(KDB) && defined(BREAK_TO_DEBUGGER)
+#if defined(KDB)
 					if (com->unit == comconsole) {
-						kdb_enter(KDB_WHY_BREAK,
-						    "Line break on console");
+						kdb_break();
 						goto cont;
 					}
 #endif
diff --git a/sys/dev/syscons/syscons.c b/sys/dev/syscons/syscons.c
index 69d628e87745..ebaa945759d0 100644
--- a/sys/dev/syscons/syscons.c
+++ b/sys/dev/syscons/syscons.c
@@ -3514,7 +3514,7 @@ next_code:
 	    case DBG:
 #ifndef SC_DISABLE_KDBKEY
 		if (enable_kdbkey)
-			kdb_enter(KDB_WHY_BREAK, "manual escape to debugger");
+			kdb_break();
 #endif
 		break;
 
diff --git a/sys/dev/uart/uart_core.c b/sys/dev/uart/uart_core.c
index 38d2a8f73773..5bd582b1a043 100644
--- a/sys/dev/uart/uart_core.c
+++ b/sys/dev/uart/uart_core.c
@@ -118,10 +118,10 @@ uart_intr_break(void *arg)
 {
 	struct uart_softc *sc = arg;
 
-#if defined(KDB) && defined(BREAK_TO_DEBUGGER)
+#if defined(KDB)
 	if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
-		kdb_enter(KDB_WHY_BREAK, "Line break on console");
-		return (0);
+		if (kdb_break())
+			return (0);
 	}
 #endif
 	if (sc->sc_opened)
@@ -170,26 +170,10 @@ uart_intr_rxready(void *arg)
 
 	rxp = sc->sc_rxput;
 	UART_RECEIVE(sc);
-#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
+#if defined(KDB)
 	if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
 		while (rxp != sc->sc_rxput) {
-			int kdb_brk;
-
-			if ((kdb_brk = kdb_alt_break(sc->sc_rxbuf[rxp++],
-			    &sc->sc_altbrk)) != 0) {
-				switch (kdb_brk) {
-				case KDB_REQ_DEBUGGER:
-					kdb_enter(KDB_WHY_BREAK,
-					    "Break sequence on console");
-					break;
-				case KDB_REQ_PANIC:
-					kdb_panic("Panic sequence on console");
-					break;
-				case KDB_REQ_REBOOT:
-					kdb_reboot();
-					break;
-				}
-			}
+			kdb_alt_break(sc->sc_rxbuf[rxp++], &sc->sc_altbrk);
 			if (rxp == sc->sc_rxbufsz)
 				rxp = 0;
 		}
diff --git a/sys/kern/subr_kdb.c b/sys/kern/subr_kdb.c
index f5cb31e71dd6..76b37a9ce7c0 100644
--- a/sys/kern/subr_kdb.c
+++ b/sys/kern/subr_kdb.c
@@ -57,6 +57,21 @@ struct pcb *kdb_thrctx = NULL;
 struct thread *kdb_thread = NULL;
 struct trapframe *kdb_frame = NULL;
 
+#ifdef BREAK_TO_DEBUGGER
+#define	KDB_BREAK_TO_DEBUGGER	1
+#else
+#define	KDB_BREAK_TO_DEBUGGER	0
+#endif
+
+#ifdef ALT_BREAK_TO_DEBUGGER
+#define	KDB_ALT_BREAK_TO_DEBUGGER	1
+#else
+#define	KDB_ALT_BREAK_TO_DEBUGGER	0
+#endif
+
+static int	kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER;
+static int	kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER;
+
 KDB_BACKEND(null, NULL, NULL, NULL);
 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
 
@@ -87,6 +102,15 @@ SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
     kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
 
+SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger, CTLTYPE_INT | CTLFLAG_RW |
+    CTLFLAG_TUN, &kdb_break_to_debugger, 0, "Enable break to debugger");
+TUNABLE_INT("debug.kdb.break_to_debugger", &kdb_break_to_debugger);
+
+SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger, CTLTYPE_INT |
+    CTLFLAG_RW | CTLFLAG_TUN, &kdb_alt_break_to_debugger, 0,
+    "Enable alternative break to debugger");
+TUNABLE_INT("debug.kdb.alt_break_to_debugger", &kdb_alt_break_to_debugger);
+
 /*
  * Flag to indicate to debuggers why the debugger was entered.
  */
@@ -241,7 +265,17 @@ enum {
 };
 
 int
-kdb_alt_break(int key, int *state)
+kdb_break(void)
+{
+
+	if (!kdb_break_to_debugger)
+		return (0);
+	kdb_enter(KDB_WHY_BREAK, "Break to debugger");
+	return (KDB_REQ_DEBUGGER);
+}
+
+static int
+kdb_alt_break_state(int key, int *state)
 {
 	int brk;
 
@@ -275,6 +309,53 @@ kdb_alt_break(int key, int *state)
 	return (brk);
 }
 
+static int
+kdb_alt_break_internal(int key, int *state, int force_gdb)
+{
+	int brk;
+
+	if (!kdb_alt_break_to_debugger)
+		return (0);
+	brk = kdb_alt_break_state(key, state);
+	switch (brk) {
+	case KDB_REQ_DEBUGGER:
+		if (force_gdb)
+			kdb_dbbe_select("gdb");
+		kdb_enter(KDB_WHY_BREAK, "Break to debugger");
+		break;
+
+	case KDB_REQ_PANIC:
+		if (force_gdb)
+			kdb_dbbe_select("gdb");
+		kdb_panic("Panic sequence on console");
+		break;
+
+	case KDB_REQ_REBOOT:
+		kdb_reboot();
+		break;
+	}
+	return (0);
+}
+
+int
+kdb_alt_break(int key, int *state)
+{
+
+	return (kdb_alt_break_internal(key, state, 0));
+}
+
+/*
+ * This variation on kdb_alt_break() is used only by dcons, which has its own
+ * configuration flag to force GDB use regardless of the global KDB
+ * configuration.
+ */
+int
+kdb_alt_break_gdb(int key, int *state)
+{
+
+	return (kdb_alt_break_internal(key, state, 1));
+}
+
 /*
  * Print a backtrace of the calling thread. The backtrace is generated by
  * the selected debugger, provided it supports backtraces. If no debugger
diff --git a/sys/pc98/cbus/sio.c b/sys/pc98/cbus/sio.c
index 01747d7d98a3..bbac9d3aee17 100644
--- a/sys/pc98/cbus/sio.c
+++ b/sys/pc98/cbus/sio.c
@@ -310,7 +310,7 @@ struct com_s {
 
 	struct	pps_state pps;
 	int	pps_bit;
-#ifdef ALT_BREAK_TO_DEBUGGER
+#ifdef KDB
 	int	alt_brk_state;
 #endif
 
@@ -1752,8 +1752,7 @@ determined_type: ;
 		}
 		if (ret)
 			device_printf(dev, "could not activate interrupt\n");
-#if defined(KDB) && (defined(BREAK_TO_DEBUGGER) || \
-    defined(ALT_BREAK_TO_DEBUGGER))
+#if defined(KDB)
 		/*
 		 * Enable interrupts for early break-to-debugger support
 		 * on the console.
@@ -1896,8 +1895,7 @@ comclose(tp)
 	sio_setreg(com, com_cfcr, com->cfcr_image &= ~CFCR_SBREAK);
 #endif
 
-#if defined(KDB) && (defined(BREAK_TO_DEBUGGER) || \
-    defined(ALT_BREAK_TO_DEBUGGER))
+#if defined(KDB)
 	/*
 	 * Leave interrupts enabled and don't clear DTR if this is the
 	 * console. This allows us to detect break-to-debugger events
@@ -2272,7 +2270,7 @@ siointr1(com)
 	u_char	rsa_buf_status = 0;
 	int	rsa_tx_fifo_size = 0;
 #endif /* PC98 */
-#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
+#if defined(KDB)
 	int	kdb_brk;
 
 again:
@@ -2369,27 +2367,11 @@ more_intr:
 			else
 				recv_data = inb(com->data_port);
 #ifdef KDB
-#ifdef ALT_BREAK_TO_DEBUGGER
 			if (com->unit == comconsole &&
 			    (kdb_brk = kdb_alt_break(recv_data,
 					&com->alt_brk_state)) != 0) {
-				mtx_unlock_spin(&sio_lock);
-				switch (kdb_brk) {
-				case KDB_REQ_DEBUGGER:
-					kdb_enter(KDB_WHY_BREAK,
-					    "Break sequence on console");
-					break;
-				case KDB_REQ_PANIC:
-					kdb_panic("panic on console");
-					break;
-				case KDB_REQ_REBOOT:
-					kdb_reboot();
-					break;
-				}
-				mtx_lock_spin(&sio_lock);
 				goto again;
 			}
-#endif /* ALT_BREAK_TO_DEBUGGER */
 #endif /* KDB */
 			if (line_status & (LSR_BI | LSR_FE | LSR_PE)) {
 				/*
@@ -2405,7 +2387,7 @@ more_intr:
 				 * Note: BI together with FE/PE means just BI.
 				 */
 				if (line_status & LSR_BI) {
-#if defined(KDB) && defined(BREAK_TO_DEBUGGER)
+#if defined(KDB)
 					if (com->unit == comconsole) {
 						kdb_enter(KDB_WHY_BREAK,
 						    "Line break on console");
diff --git a/sys/powerpc/mambo/mambo_console.c b/sys/powerpc/mambo/mambo_console.c
index a5ef2f9de35d..553071c63f38 100644
--- a/sys/powerpc/mambo/mambo_console.c
+++ b/sys/powerpc/mambo/mambo_console.c
@@ -60,7 +60,7 @@ static int			polltime;
 static struct callout		mambo_callout;
 static struct tty 		*tp = NULL;
 
-#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
+#if defined(KDB)
 static int			alt_break_state;
 #endif
 
@@ -156,24 +156,8 @@ mambo_cngetc(struct consdev *cp)
 	ch = mambocall(MAMBO_CONSOLE_READ);
 
 	if (ch > 0 && ch < 0xff) {
-#if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
-		int kdb_brk;
-
-		if ((kdb_brk = kdb_alt_break(ch, &alt_break_state)) != 0) {
-			switch (kdb_brk) {
-			case KDB_REQ_DEBUGGER:
-				kdb_enter(KDB_WHY_BREAK,
-				    "Break sequence on console");
-				break;
-			case KDB_REQ_PANIC:
-				kdb_panic("Panic sequence on console");
-				break;
-			case KDB_REQ_REBOOT:
-				kdb_reboot();
-				break;
-
-			}
-		}
+#if defined(KDB)
+		kdb_alt_break(ch, &alt_break_state);
 #endif
 		return (ch);
 	}
diff --git a/sys/sys/kdb.h b/sys/sys/kdb.h
index 2982e03c75f1..61ee0973eb14 100644
--- a/sys/sys/kdb.h
+++ b/sys/sys/kdb.h
@@ -64,6 +64,8 @@ extern struct pcb *kdb_thrctx;		/* Current context. */
 extern struct thread *kdb_thread;	/* Current thread. */
 
 int	kdb_alt_break(int, int *);
+int	kdb_alt_break_gdb(int, int *);
+int	kdb_break(void);
 void	kdb_backtrace(void);
 int	kdb_dbbe_select(const char *);
 void	kdb_enter(const char *, const char *);