- Add a function db_alt_break which recognizes the character sequence used to

implement ALT_BREAK_TO_DEBUGGER.  The caller provides a pointer to a state
  variable to allow different state to be maintained for separate instances of
  a device.
- Use struct vm_map * instead of vm_map_t in db_break.h to avoid its users
  needing to include vm headers.

Requested by:	njl

sys/ddb/db_break.c

@@ -33,6 +33,8 @@
 /*
  * Breakpoints.
  */
+#include "opt_comconsole.h"
+
 #include <sys/param.h>
 
 #include <vm/vm.h>
@@ -363,3 +365,45 @@ db_map_addr(addr)
 #endif
 	    return kernel_map;
 }
+
+#ifdef ALT_BREAK_TO_DEBUGGER
+/*
+ * Solaris implements a new BREAK which is initiated by a character sequence
+ * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
+ * Remote Console.
+ *
+ * Note that this function may be called from almost anywhere, with interrupts
+ * disabled and with unknown locks held, so it must not access data other than
+ * its arguments.  Its up to the caller to ensure that the state variable is
+ * consistent.
+ */
+
+#define	KEY_CR		13	/* CR '\r' */
+#define	KEY_TILDE	126	/* ~ */
+#define	KEY_CRTLB	2	/* ^B */
+
+int
+db_alt_break(int data, int *state)
+{
+	int brk = 0;
+
+	switch (data) {
+	case KEY_CR:
+		*state = KEY_TILDE;
+		break;
+	case KEY_TILDE:
+		if (*state == KEY_TILDE)
+			*state = KEY_CRTLB;
+		else
+			*state = 0;
+		break;
+	case KEY_CRTLB:
+		if (*state == KEY_CRTLB)
+			brk = 1;
+	default:
+		*state = 0;
+		break;
+	}
+	return (brk);
+}
+#endif

sys/ddb/db_break.h

@@ -41,8 +41,10 @@
 #define BKPT_INST_TYPE int
 #endif
 
+struct vm_map;
+
 struct db_breakpoint {
-	vm_map_t map;			/* in this map */
+	struct vm_map *map;			/* in this map */
 	db_addr_t address;		/* set here */
 	int	init_count;		/* number of times to skip bkpt */
 	int	count;			/* current count */
@@ -64,4 +66,8 @@ void		db_set_breakpoints(void);
 db_breakpoint_t	db_set_temp_breakpoint(db_addr_t);
 #endif
 
+#ifdef ALT_BREAK_TO_DEBUGGER
+int		db_alt_break(int, int *);
+#endif
+
 #endif /* !_DDB_DB_BREAK_H_ */