Add a new 'why' argument to kdb_enter(), and a set of constants to use

for that argument.  This will allow DDB to detect the broad category of
reason why the debugger has been entered, which it can use for the
purposes of deciding which DDB script to run.

Assign approximate why values to all current consumers of the
kdb_enter() interface.

sys/amd64/amd64/machdep.c

@@ -1277,7 +1277,8 @@ hammer_time(u_int64_t modulep, u_int64_t physfree)
 
 #ifdef KDB
 	if (boothowto & RB_KDB)
-		kdb_enter("Boot flags requested debugger");
+		kdb_enter(KDB_WHY_BOOTFLAGS,
+		    "Boot flags requested debugger");
 #endif
 
 	identify_cpu();		/* Final stage of CPU initialization */

sys/amd64/amd64/mp_watchdog.c

@@ -203,7 +203,7 @@ ap_watchdog(u_int cpuid)
 			if (watchdog_nmi)
 				watchdog_ipi_nmi();
 			else
-				kdb_enter("mp_watchdog");
+				kdb_enter(KDB_WHY_WATCHDOG, "mp_watchdog");
 		}
 	}
 	bcopy(old_pcomm, p->p_comm, MAXCOMLEN + 1);

sys/arm/at91/uart_dev_at91usart.c

@@ -508,7 +508,7 @@ at91_rx_put(struct uart_softc *sc, int key)
 #if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
 	if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
 		if (kdb_alt_break(key, &sc->sc_altbrk))
-			kdb_enter("Break sequence to console");
+			kdb_enter(KDB_WHY_BREAK, "Break sequence to console");
 	}
 #endif
 	uart_rx_put(sc, key);	

sys/cam/scsi/scsi_low.h

@@ -87,7 +87,7 @@
 
 #ifdef	__FreeBSD__
 #undef	MSG_IDENTIFY
-#define	SCSI_LOW_DEBUGGER(dev)	kdb_enter(dev)
+#define	SCSI_LOW_DEBUGGER(dev)	kdb_enter(KDB_WHY_CAM, dev)
 #define	SCSI_LOW_DELAY(mu)	DELAY((mu))
 #define	SCSI_LOW_SPLSCSI	splcam
 #define	SCSI_LOW_BZERO(pt, size)	bzero((pt), (size))

sys/compat/ndis/subr_ntoskrnl.c

@@ -3632,7 +3632,7 @@ DbgBreakPoint(void)
 #if __FreeBSD_version < 502113
 	Debugger("DbgBreakPoint(): breakpoint");
 #else
-	kdb_enter("DbgBreakPoint(): breakpoint");
+	kdb_enter(KDB_WHY_NDIS, "DbgBreakPoint(): breakpoint");
 #endif
 }
 

sys/dev/acpica/Osd/OsdDebug.c

@@ -73,13 +73,13 @@ AcpiOsSignal(UINT32 Function, void *Info)
 	printf("ACPI fatal signal, type 0x%x code 0x%x argument 0x%x",
 	      fatal->Type, fatal->Code, fatal->Argument);
 #ifdef ACPI_DEBUG
-	kdb_enter("AcpiOsSignal");
+	kdb_enter(KDB_WHY_ACPI, "AcpiOsSignal");
 #endif
 	break;
 
     case ACPI_SIGNAL_BREAKPOINT:
 #ifdef ACPI_DEBUG
-	kdb_enter((char *)Info);
+	kdb_enter(KDB_WHY_ACPI, (char *)Info);
 #endif
 	break;
 

sys/dev/dcons/dcons_os.c

@@ -207,11 +207,13 @@ dcons_check_break(struct dcons_softc *dc, int c)
 #ifdef GDB
 			if (gdb_cur == &dcons_gdb_dbgport) {
 				kdb_dbbe_select("gdb");
-				kdb_enter("Break sequence on dcons gdb port");
+				kdb_enter(KDB_WHY_BREAK,
+				    "Break sequence on dcons gdb port");
 			}
 #endif
 		} else
-			kdb_enter("Break sequence on dcons console port");
+			kdb_enter(KDB_WHY_BREAK,
+			    "Break sequence on dcons console port");
 	}
 #else
 	switch (dc->brk_state) {

sys/dev/ofw/ofw_console.c

@@ -282,7 +282,7 @@ ofw_cngetc(struct consdev *cp)
 	if (OF_read(stdin, &ch, 1) > 0) {
 #if defined(KDB) && defined(ALT_BREAK_TO_DEBUGGER)
 		if (kdb_alt_break(ch, &alt_break_state))
-			kdb_enter("Break sequence on console");
+			kdb_enter(KDB_WHY_BREAK, "Break sequence on console");
 #endif
 		return (ch);
 	}

sys/dev/sio/sio.c

@@ -1502,7 +1502,8 @@ siointr1(com)
 #ifdef ALT_BREAK_TO_DEBUGGER
 			if (com->unit == comconsole &&
 			    kdb_alt_break(recv_data, &com->alt_brk_state) != 0)
-				kdb_enter("Break sequence on console");
+				kdb_enter(KDB_WHY_BREAK,
+				    "Break sequence on console");
 #endif /* ALT_BREAK_TO_DEBUGGER */
 #endif /* KDB */
 			if (line_status & (LSR_BI | LSR_FE | LSR_PE)) {
@@ -1521,7 +1522,8 @@ siointr1(com)
 				if (line_status & LSR_BI) {
 #if defined(KDB) && defined(BREAK_TO_DEBUGGER)
 					if (com->unit == comconsole) {
-						kdb_enter("Line break on console");
+						kdb_enter(KDB_WHY_BREAK,
+						    "Line break on console");
 						goto cont;
 					}
 #endif

sys/dev/syscons/syscons.c

@@ -3373,7 +3373,7 @@ scgetc(sc_softc_t *sc, u_int flags)
 	    case DBG:
 #ifndef SC_DISABLE_KDBKEY
 		if (enable_kdbkey)
-			kdb_enter("manual escape to debugger");
+			kdb_enter(KDB_WHY_BREAK, "manual escape to debugger");
 #endif
 		break;
 

sys/dev/uart/uart_core.c

@@ -122,7 +122,7 @@ uart_intr_break(void *arg)
 
 #if defined(KDB) && defined(BREAK_TO_DEBUGGER)
 	if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
-		kdb_enter("Line break on console");
+		kdb_enter(KDB_WHY_BREAK, "Line break on console");
 		return (0);
 	}
 #endif
@@ -176,7 +176,8 @@ uart_intr_rxready(void *arg)
 	if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
 		while (rxp != sc->sc_rxput) {
 			if (kdb_alt_break(sc->sc_rxbuf[rxp++], &sc->sc_altbrk))
-				kdb_enter("Break sequence on console");
+				kdb_enter(KDB_WHY_BREAK,
+				    "Break sequence on console");
 			if (rxp == sc->sc_rxbufsz)
 				rxp = 0;
 		}

sys/fs/unionfs/union_subr.c

@@ -1062,7 +1062,8 @@ unionfs_checkuppervp(struct vnode *vp, char *fil, int lno)
 	if (vp->v_op != unionfs_vnodeop_p) {
 		printf("unionfs_checkuppervp: on non-unionfs-node.\n");
 #ifdef KDB
-		kdb_enter("unionfs_checkuppervp: on non-unionfs-node.\n");
+		kdb_enter(KDB_WHY_UNIONFS,
+		    "unionfs_checkuppervp: on non-unionfs-node.\n");
 #endif
 		panic("unionfs_checkuppervp");
 	};
@@ -1081,7 +1082,8 @@ unionfs_checklowervp(struct vnode *vp, char *fil, int lno)
 	if (vp->v_op != unionfs_vnodeop_p) {
 		printf("unionfs_checklowervp: on non-unionfs-node.\n");
 #ifdef KDB
-		kdb_enter("unionfs_checklowervp: on non-unionfs-node.\n");
+		kdb_enter(KDB_WHY_UNIONFS,
+		    "unionfs_checklowervp: on non-unionfs-node.\n");
 #endif
 		panic("unionfs_checklowervp");
 	};

sys/i386/i386/machdep.c

@@ -2275,7 +2275,7 @@ init386(first)
 
 #ifdef KDB
 	if (boothowto & RB_KDB)
-		kdb_enter("Boot flags requested debugger");
+		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
 #endif
 
 	finishidentcpu();	/* Final stage of CPU initialization */

sys/i386/i386/mp_watchdog.c

@@ -203,7 +203,7 @@ ap_watchdog(u_int cpuid)
 			if (watchdog_nmi)
 				watchdog_ipi_nmi();
 			else
-				kdb_enter("mp_watchdog");
+				kdb_enter(KDB_WHY_WATCHDOG, "mp_watchdog");
 		}
 	}
 	bcopy(old_pcomm, p->p_comm, MAXCOMLEN + 1);

sys/ia64/ia64/machdep.c

@@ -824,7 +824,8 @@ ia64_init(void)
 
 #ifdef KDB
 	if (boothowto & RB_KDB)
-		kdb_enter("Boot flags requested debugger\n");
+		kdb_enter(KDB_WHY_BOOTFLAGS,
+		    "Boot flags requested debugger\n");
 #endif
 
 	ia64_set_tpr(0);

sys/kern/kern_clock.c

@@ -637,7 +637,7 @@ watchdog_fire(void)
 
 #if defined(KDB) && !defined(KDB_UNATTENDED)
 	kdb_backtrace();
-	kdb_enter("watchdog timeout");
+	kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
 #else
 	panic("watchdog timeout");
 #endif

sys/kern/kern_shutdown.c

@@ -544,7 +544,7 @@ panic(const char *fmt, ...)
 	if (newpanic && trace_on_panic)
 		kdb_backtrace();
 	if (debugger_on_panic)
-		kdb_enter("panic");
+		kdb_enter(KDB_WHY_PANIC, "panic");
 #ifdef RESTARTABLE_PANICS
 	/* See if the user aborted the panic, in which case we continue. */
 	if (panicstr == NULL) {

sys/kern/subr_kdb.c

@@ -97,6 +97,11 @@ SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLTYPE_INT | CTLFLAG_RW,
 TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus);
 #endif
 
+/*
+ * Flag to indicate to debuggers why the debugger was entered.
+ */
+const char * volatile kdb_why = KDB_WHY_UNSET;
+
 static int
 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
 {
@@ -163,7 +168,7 @@ kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
 		return (error);
 	if (kdb_active)
 		return (EBUSY);
-	kdb_enter("sysctl debug.kdb.enter");
+	kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
 	return (0);
 }
 
@@ -295,17 +300,20 @@ kdb_dbbe_select(const char *name)
  * Enter the currently selected debugger. If a message has been provided,
  * it is printed first. If the debugger does not support the enter method,
  * it is entered by using breakpoint(), which enters the debugger through
- * kdb_trap().
+ * kdb_trap().  The 'why' argument will contain a more mechanically usable
+ * string than 'msg', and is relied upon by DDB scripting to identify the
+ * reason for entering the debugger so that the right script can be run.
  */
-
 void
-kdb_enter(const char *msg)
+kdb_enter(const char *why, const char *msg)
 {
 
 	if (kdb_dbbe != NULL && kdb_active == 0) {
 		if (msg != NULL)
 			printf("KDB: enter: %s\n", msg);
+		kdb_why = why;
 		breakpoint();
+		kdb_why = KDB_WHY_UNSET;
 	}
 }
 

sys/kern/subr_witness.c

@@ -1123,7 +1123,7 @@ witness_checkorder(struct lock_object *lock, int flags, const char *file,
 	if (witness_trace)
 		kdb_backtrace();
 	if (witness_kdb)
-		kdb_enter(__func__);
+		kdb_enter(KDB_WHY_WITNESS, __func__);
 #endif
 }
 
@@ -1396,7 +1396,7 @@ witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
 		panic("witness_warn");
 #ifdef KDB
 	else if (witness_kdb && n)
-		kdb_enter(__func__);
+		kdb_enter(KDB_WHY_WITNESS, __func__);
 	else if (witness_trace && n)
 		kdb_backtrace();
 #endif

sys/kern/vfs_subr.c

@@ -3456,7 +3456,7 @@ vfs_badlock(const char *msg, const char *str, struct vnode *vp)
 	if (vfs_badlock_print)
 		printf("%s: %p %s\n", str, (void *)vp, msg);
 	if (vfs_badlock_ddb)
-		kdb_enter("lock violation");
+		kdb_enter(KDB_WHY_VFSLOCK, "lock violation");
 }
 
 void
@@ -3576,7 +3576,7 @@ vop_strategy_pre(void *ap)
 			printf(
 			    "VOP_STRATEGY: bp is not locked but should be\n");
 		if (vfs_badlock_ddb)
-			kdb_enter("lock violation");
+			kdb_enter(KDB_WHY_VFSLOCK, "lock violation");
 	}
 #endif
 }

sys/netgraph/ng_base.c

@@ -3465,12 +3465,12 @@ ng_setisr(node_p node)
 	do {								\
 		if (NGI_NODE(item) ) {					\
 			printf("item already has node");		\
-			kdb_enter("has node");				\
+			kdb_enter(KDB_WHY_NETGRAPH, "has node");	\
 			NGI_CLR_NODE(item);				\
 		}							\
 		if (NGI_HOOK(item) ) {					\
 			printf("item already has hook");		\
-			kdb_enter("has hook");				\
+			kdb_enter(KDB_WHY_NETGRAPH, "has hook");	\
 			NGI_CLR_HOOK(item);				\
 		}							\
 	} while (0)

sys/pc98/cbus/sio.c

@@ -2369,7 +2369,8 @@ status_read:;
 #ifdef ALT_BREAK_TO_DEBUGGER
 			if (com->unit == comconsole &&
 			    kdb_alt_break(recv_data, &com->alt_brk_state) != 0)
-				kdb_enter("Break sequence on console");
+				kdb_enter(KDB_WHY_BREAK,
+				    "Break sequence on console");
 #endif /* ALT_BREAK_TO_DEBUGGER */
 #endif /* KDB */
 			if (line_status & (LSR_BI | LSR_FE | LSR_PE)) {
@@ -2388,7 +2389,8 @@ status_read:;
 				if (line_status & LSR_BI) {
 #if defined(KDB) && defined(BREAK_TO_DEBUGGER)
 					if (com->unit == comconsole) {
-						kdb_enter("Line break on console");
+						kdb_enter(KDB_WHY_BREAK,
+						    "Line break on console");
 						goto cont;
 					}
 #endif

sys/pc98/pc98/machdep.c

@@ -2061,7 +2061,7 @@ init386(first)
 
 #ifdef KDB
 	if (boothowto & RB_KDB)
-		kdb_enter("Boot flags requested debugger");
+		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
 #endif
 
 	finishidentcpu();	/* Final stage of CPU initialization */

sys/powerpc/aim/machdep.c

@@ -398,7 +398,8 @@ powerpc_init(u_int startkernel, u_int endkernel, u_int basekernel, void *mdp)
 
 #ifdef KDB
 	if (boothowto & RB_KDB)
-		kdb_enter("Boot flags requested debugger");
+		kdb_enter(KDB_WHY_BOOTFLAGS,
+		    "Boot flags requested debugger");
 #endif
 }
 

sys/powerpc/powermac/pswitch.c

@@ -139,6 +139,6 @@ pswitch_intr(void *arg)
 
 	dev = (device_t)arg;
 
-	kdb_enter(device_get_nameunit(dev));
+	kdb_enter(KDB_WHY_POWERPC, device_get_nameunit(dev));
 	return (FILTER_HANDLED);
 }

sys/security/mac_test/mac_test.c

@@ -117,7 +117,7 @@ SYSCTL_NODE(_security_mac_test, OID_AUTO, counter, CTLFLAG_RW, 0,
 #define	COUNTER_INC(variable)	atomic_add_int(&counter_##variable, 1)
 
 #ifdef KDB
-#define	DEBUGGER(func, string)	kdb_enter((string))
+#define	DEBUGGER(func, string)	kdb_enter(KDB_WHY_MAC, (string))
 #else
 #define	DEBUGGER(func, string)	printf("mac_test: %s: %s\n", (func), (string))
 #endif

sys/sparc64/pci/psycho.c

@@ -850,7 +850,7 @@ psycho_powerfail(void *arg)
 #ifdef DEBUGGER_ON_POWERFAIL
 	struct psycho_softc *sc = arg;
 
-	kdb_enter("powerfail");
+	kdb_enter(KDB_WHY_POWERFAIL, "powerfail");
 #else
 	static int shutdown;
 

sys/sparc64/sparc64/machdep.c

@@ -448,7 +448,7 @@ sparc64_init(caddr_t mdp, u_long o1, u_long o2, u_long o3, ofw_vec_t *vec)
 
 #ifdef KDB
 	if (boothowto & RB_KDB)
-		kdb_enter("Boot flags requested debugger");
+		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
 #endif
 }
 

sys/sparc64/sparc64/trap.c

@@ -289,7 +289,7 @@ trap(struct trapframe *tf)
 			}
 			if (debugger_on_signal &&
 			    (sig == 4 || sig == 10 || sig == 11))
-				kdb_enter("trapsig");
+				kdb_enter(KDB_WHY_TRAPSIG, "trapsig");
 			ksiginfo_init_trap(&ksi);
 			ksi.ksi_signo = sig;
 			ksi.ksi_code = (int)tf->tf_type; /* XXX not POSIX */

sys/sun4v/sun4v/hvcons.c

@@ -224,10 +224,10 @@ hvcn_cngetc(struct consdev *cp)
 	while ((l = hv_cons_getchar(&ch)) != H_EOK) {
 #if defined(KDB)
 		if (l == H_BREAK || l ==  H_HUP)
-			kdb_enter("Break sequence on console");
+			kdb_enter(KDB_WHY_BREAK, "Break sequence on console");
 
 	if (kdb_alt_break(ch, &alt_break_state))
-		kdb_enter("Break sequence on console");
+		kdb_enter(KDB_WHY_BREAK, "Break sequence on console");
 #endif
 		if (l != -2 && l != 0) {
 			return (-1);
@@ -248,9 +248,9 @@ hvcn_cncheckc(struct consdev *cp)
 	if ((l = hv_cons_getchar(&ch)) == H_EOK) {
 #if defined(KDB)
 		if (l == H_BREAK || l ==  H_HUP)
-			kdb_enter("Break sequence on console");
+			kdb_enter(KDB_WHY_BREAK, "Break sequence on console");
 		if (kdb_alt_break(ch, &alt_break_state))
-			kdb_enter("Break sequence on console");
+			kdb_enter(KDB_WHY_BREAK, "Break sequence on console");
 #endif
 		return (ch);
 	}

sys/sun4v/sun4v/machdep.c

@@ -510,7 +510,7 @@ sparc64_init(caddr_t mdp, u_long o1, u_long o2, u_long o3, ofw_vec_t *vec)
 
 #ifdef KDB
 	if (boothowto & RB_KDB)
-		kdb_enter("Boot flags requested debugger");
+		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
 #endif
 	BVPRINTF("sparc64_init done\n");
 }

sys/sun4v/sun4v/trap.c

@@ -366,7 +366,7 @@ trap(struct trapframe *tf, int64_t type, uint64_t data)
 			}
 			if (debugger_on_signal &&
 			    (sig == 4 || sig == 10 || sig == 11))
-				kdb_enter("trapsig");
+				kdb_enter(KDB_WHY_TRAPSIG, "trapsig");
 #ifdef VERBOSE
 			if (sig == 4 || sig == 10 || sig == 11)
 				printf("trap: %ld:%s: 0x%lx at 0x%lx on cpu=%d sig=%d proc=%s\n", 

sys/sys/kdb.h

@@ -66,7 +66,7 @@ extern struct thread *kdb_thread;	/* Current thread. */
 int	kdb_alt_break(int, int *);
 void	kdb_backtrace(void);
 int	kdb_dbbe_select(const char *);
-void	kdb_enter(const char *);
+void	kdb_enter(const char *, const char *);
 void	kdb_init(void);
 void *	kdb_jmpbuf(jmp_buf);
 void	kdb_reenter(void);
@@ -78,4 +78,31 @@ struct thread *kdb_thr_next(struct thread *);
 int	kdb_thr_select(struct thread *);
 int	kdb_trap(int, int, struct trapframe *);
 
+/*
+ * KDB enters the debugger via breakpoint(), which leaves the debugger without
+ * a lot of information about why it was entered.  This simple enumerated set
+ * captures some basic information.
+ *
+ * It is recommended that values here be short (<16 character) alpha-numeric
+ * strings, as they will be used to construct DDB(4) script names.
+ */
+extern const char * volatile kdb_why;
+#define	KDB_WHY_UNSET		NULL		/* No reason set. */
+#define	KDB_WHY_PANIC		"panic"		/* panic() was called. */
+#define	KDB_WHY_SYSCTL		"sysctl"	/* Sysctl entered debugger. */
+#define	KDB_WHY_BOOTFLAGS	"bootflags"	/* Boot flags were set. */
+#define	KDB_WHY_WITNESS		"witness"	/* Witness entered debugger. */
+#define	KDB_WHY_VFSLOCK		"vfslock"	/* VFS detected lock problem. */
+#define	KDB_WHY_NETGRAPH	"netgraph"	/* Netgraph entered debugger. */
+#define	KDB_WHY_BREAK		"break"		/* Console or serial break. */
+#define	KDB_WHY_WATCHDOG	"watchdog"	/* Watchdog entered debugger. */
+#define	KDB_WHY_CAM		"cam"		/* CAM has entered debugger. */
+#define	KDB_WHY_NDIS		"ndis"		/* NDIS entered debugger. */
+#define	KDB_WHY_ACPI		"acpi"		/* ACPI entered debugger. */
+#define	KDB_WHY_TRAPSIG		"trapsig"	/* Sun4v/Sparc fault. */
+#define	KDB_WHY_POWERFAIL	"powerfail"	/* Powerfail NMI. */
+#define	KDB_WHY_MAC		"mac"		/* MAC Framework. */
+#define	KDB_WHY_POWERPC		"powerpc"	/* Unhandled powerpc intr. */
+#define	KDB_WHY_UNIONFS		"unionfs"	/* Unionfs bug. */
+
 #endif /* !_SYS_KDB_H_ */