Make ddb command registration dynamic so modules can extend

the command set (only so long as the module is present):
o add db_command_register and db_command_unregister to add and remove
  commands, respectively
o replace linker sets with SYSINIT's (and SYSUINIT's) that register
  commands
o expose 3 list heads: db_cmd_table, db_show_table, and db_show_all_table
  for registering top-level commands, show operands, and show all operands,
  respectively

While here also:
o sort command lists
o add DB_ALIAS, DB_SHOW_ALIAS, and DB_SHOW_ALL_ALIAS to add aliases
  for existing commands
o add "show all trace" as an alias for "show alltrace"
o add "show all locks" as an alias for "show alllocks"

Submitted by:	Guillaume Ballet <gballet@gmail.com> (original version)
Reviewed by:	jhb
MFC after:	1 month

1 files changed, 90 insertions, 46 deletions

diff --git a/sys/ddb/ddb.h b/sys/ddb/ddb.h
index 57c5fd15985c..1afdfa39a54e 100644
--- a/sys/ddb/ddb.h
+++ b/sys/ddb/ddb.h
@@ -43,6 +43,9 @@ SYSCTL_DECL(_debug_ddb);
 
 #include <machine/db_machdep.h>		/* type definitions */
 
+#include <sys/queue.h>			/* LIST_* */
+#include <sys/kernel.h>			/* SYSINIT */
+
 #ifndef DB_MAXARGS
 #define	DB_MAXARGS	10
 #endif
@@ -73,36 +76,97 @@ SYSCTL_DECL(_debug_ddb);
 int	DB_CALL(db_expr_t, db_expr_t *, int, db_expr_t[]);
 #endif
 
+/*
+ * There are three "command tables":
+ * - One for simple commands; a list of these is displayed
+ *   by typing 'help' at the debugger prompt.
+ * - One for sub-commands of 'show'; to see this type 'show'
+ *   without any arguments.
+ * - The last one for sub-commands of 'show all'; type 'show all'
+ *   without any argument to get a list.
+ */
+struct command;
+LIST_HEAD(command_table, command);
+extern struct command_table db_cmd_table;
+extern struct command_table db_show_table;
+extern struct command_table db_show_all_table;
+
+/*
+ * Type signature for a function implementing a ddb command.
+ */
 typedef void db_cmdfcn_t(db_expr_t addr, boolean_t have_addr, db_expr_t count,
 	    char *modif);
 
-#define DB_COMMAND(cmd_name, func_name) \
-	DB_FUNC(cmd_name, func_name, db_cmd_set, 0, NULL)
-#define DB_SHOW_COMMAND(cmd_name, func_name) \
-	DB_FUNC(cmd_name, func_name, db_show_cmd_set, 0, NULL)
-#define DB_SHOW_ALL_COMMAND(cmd_name, func_name) \
-	DB_FUNC(cmd_name, func_name, db_show_all_cmd_set, 0, NULL)
-
-#define	DB_SET(cmd_name, func_name, set, flag, more)		\
-static const struct command __CONCAT(cmd_name,_cmd) = {		\
-	__STRING(cmd_name),					\
-	func_name,						\
-	flag,							\
-	more							\
+/*
+ * Command table entry.
+ */
+struct command {
+	char *	name;		/* command name */
+	db_cmdfcn_t *fcn;	/* function to call */
+	int	flag;		/* extra info: */
+#define	CS_OWN		0x1	/* non-standard syntax */
+#define	CS_MORE		0x2	/* standard syntax, but may have other words
+				 * at end */
+#define	CS_SET_DOT	0x100	/* set dot after command */
+	struct command_table *more; /* another level of command */
+	LIST_ENTRY(command) next; /* next entry in the command table */
+};
+
+/*
+ * Arrange for the specified ddb command to be defined and
+ * bound to the specified function.  Commands can be defined
+ * in modules in which case they will be available only when
+ * the module is loaded.
+ */
+#define _DB_SET(_suffix, _name, _func, list, _flag, _more)	\
+static struct command __CONCAT(_name,_suffix) = {		\
+	.name	= __STRING(_name),				\
+	.fcn	= _func,					\
+	.flag	= _flag,					\
+	.more	= _more						\
 };								\
-TEXT_SET(set, __CONCAT(cmd_name,_cmd))
+static void __CONCAT(__CONCAT(_name,_suffix),_add)(void *arg __unused) \
+    { db_command_register(&list, &__CONCAT(_name,_suffix)); }	\
+SYSINIT(__CONCAT(_name,_suffix), SI_SUB_KLD, SI_ORDER_ANY,	\
+    __CONCAT(__CONCAT(_name,_suffix),_add), NULL);		\
+static void __CONCAT(__CONCAT(_name,_suffix),_del)(void *arg __unused) \
+    { db_command_unregister(&list, &__CONCAT(_name,_suffix)); }	\
+SYSUNINIT(__CONCAT(_name,_suffix), SI_SUB_KLD, SI_ORDER_ANY,	\
+    __CONCAT(__CONCAT(_name,_suffix),_del), NULL);
 
-#define DB_FUNC(cmd_name, func_name, set, flag, more)		\
-static db_cmdfcn_t	func_name;				\
-								\
-DB_SET(cmd_name, func_name, set, flag, more);			\
-								\
+/*
+ * Like _DB_SET but also create the function declaration which
+ * must be followed immediately by the body; e.g.
+ *   _DB_FUNC(_cmd, panic, db_panic, db_cmd_table, 0, NULL)
+ *   {
+ *	...panic implementation...
+ *   }
+ *
+ * This macro is mostly used to define commands placed in one of
+ * the ddb command tables; see DB_COMMAND, etc. below.
+ */
+#define _DB_FUNC(_suffix, _name, _func, list, _flag, _more)	\
+static db_cmdfcn_t _func;					\
+_DB_SET(_suffix, _name, _func, list, _flag, _more);		\
 static void							\
-func_name(addr, have_addr, count, modif)			\
-	db_expr_t addr;						\
-	boolean_t have_addr;					\
-	db_expr_t count;					\
-	char *modif;
+_func(db_expr_t addr, boolean_t have_addr, db_expr_t count, char *modif)
+
+/* common idom provided for backwards compatibility */
+#define DB_FUNC(_name, _func, list, _flag, _more)		\
+	_DB_FUNC(_cmd, _name, _func, list, _flag, _more)
+
+#define DB_COMMAND(cmd_name, func_name) \
+	_DB_FUNC(_cmd, cmd_name, func_name, db_cmd_table, 0, NULL)
+#define DB_ALIAS(alias_name, func_name) \
+	_DB_SET(_cmd, alias_name, func_name, db_cmd_table, 0, NULL)
+#define DB_SHOW_COMMAND(cmd_name, func_name) \
+	_DB_FUNC(_show, cmd_name, func_name, db_show_table, 0, NULL)
+#define DB_SHOW_ALIAS(alias_name, func_name) \
+	_DB_SET(_show, alias_name, func_name, db_show_table, 0, NULL)
+#define DB_SHOW_ALL_COMMAND(cmd_name, func_name) \
+	_DB_FUNC(_show_all, cmd_name, func_name, db_show_all_table, 0, NULL)
+#define DB_SHOW_ALL_ALIAS(alias_name, func_name) \
+	_DB_SET(_show_all, alias_name, func_name, db_show_all_table, 0, NULL)
 
 extern db_expr_t db_maxoff;
 extern int db_indent;
@@ -150,6 +214,8 @@ void		db_trace_self(void);
 int		db_trace_thread(struct thread *, int);
 int		db_value_of_name(const char *name, db_expr_t *valuep);
 int		db_write_bytes(vm_offset_t addr, size_t size, char *data);
+void		db_command_register(struct command_table *, struct command *);
+void		db_command_unregister(struct command_table *, struct command *);
 
 db_cmdfcn_t	db_breakpoint_cmd;
 db_cmdfcn_t	db_capture_cmd;
@@ -179,28 +245,6 @@ db_cmdfcn_t	db_watchpoint_cmd;
 db_cmdfcn_t	db_write_cmd;
 
 /*
- * Command table.
- */
-struct command;
-
-struct command_table {
-	struct command *table;
-	struct command **aux_tablep;
-	struct command **aux_tablep_end;
-};
-
-struct command {
-	char *	name;		/* command name */
-	db_cmdfcn_t *fcn;	/* function to call */
-	int	flag;		/* extra info: */
-#define	CS_OWN		0x1	/* non-standard syntax */
-#define	CS_MORE		0x2	/* standard syntax, but may have other words
-				 * at end */
-#define	CS_SET_DOT	0x100	/* set dot after command */
-	struct command_table *more; /* another level of command */
-};
-
-/*
  * Interface between DDB and the DDB output capture facility.
  */
 struct dumperinfo;