xref: /src/sys/ddb/db_command.c

/*	$NetBSD: db_command.c,v 1.108 2007/10/14 00:37:56 uwe Exp $	*/
/*
 * Mach Operating System
 * Copyright (c) 1991,1990 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */
/*
 * Copyright (c) 1996, 1997, 1998, 1999, 2002 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Adam Hamsik.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *        This product includes software developed by the NetBSD
 *        Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Command dispatcher.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: db_command.c,v 1.108 2007/10/14 00:37:56 uwe Exp $");

#include "opt_ddb.h"
#include "opt_kgdb.h"
#include "opt_inet.h"
#include "opt_ddbparam.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/reboot.h>
#include <sys/device.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/namei.h>
#include <sys/pool.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/lockdebug.h>
#include <sys/sleepq.h>

/*include queue macros*/
#include <sys/queue.h>

#include <machine/db_machdep.h>		/* type definitions */

#if defined(_KERNEL_OPT)
#include "opt_multiprocessor.h"
#endif
#ifdef MULTIPROCESSOR
#include <machine/cpu.h>
#endif

#include <ddb/db_lex.h>
#include <ddb/db_output.h>
#include <ddb/db_command.h>
#include <ddb/db_break.h>
#include <ddb/db_watch.h>
#include <ddb/db_run.h>
#include <ddb/db_variables.h>
#include <ddb/db_interface.h>
#include <ddb/db_sym.h>
#include <ddb/db_extern.h>

#include <uvm/uvm_extern.h>
#include <uvm/uvm_ddb.h>

#include "arp.h"

/*
 * Results of command search.
 */
#define	CMD_UNIQUE	0
#define	CMD_FOUND	1
#define	CMD_NONE	2
#define	CMD_AMBIGUOUS	3

/*
 * Exported global variables
 */
bool		db_cmd_loop_done;
label_t		*db_recover;
db_addr_t	db_dot;
db_addr_t	db_last_addr;
db_addr_t	db_prev;
db_addr_t	db_next;


/*
  New DDB api for adding and removing commands uses three lists, because
  we use two types of commands
  a) standard commands without subcommands -> reboot
  b) show commands which are subcommands of show command -> show aio_jobs
  c) if defined machine specific commands

  ddb_add_cmd, ddb_rem_cmd use type (DDB_SHOW_CMD||DDB_BASE_CMD)argument to
  add them to representativ lists.
*/

static const struct db_command db_command_table[];
static const struct db_command db_show_cmds[];
#ifdef DB_MACHINE_COMMANDS
static const struct db_command db_machine_command_table[];
#endif

/* the global queue of all command tables */
TAILQ_HEAD(db_cmd_tbl_en_head, db_cmd_tbl_en);

/* TAILQ entry used to register command tables */
struct db_cmd_tbl_en {
	const struct db_command *db_cmd;	/* cmd table */
	TAILQ_ENTRY(db_cmd_tbl_en) db_cmd_next;
};

/* head of base commands list */
static struct db_cmd_tbl_en_head db_base_cmd_list =
	TAILQ_HEAD_INITIALIZER(db_base_cmd_list);
static struct db_cmd_tbl_en db_base_cmd_builtins =
     { .db_cmd = db_command_table };

/* head of show commands list */
static struct db_cmd_tbl_en_head db_show_cmd_list =
	TAILQ_HEAD_INITIALIZER(db_show_cmd_list);
static struct db_cmd_tbl_en db_show_cmd_builtins =
     { .db_cmd = db_show_cmds };

/* head of machine commands list */
static struct db_cmd_tbl_en_head db_mach_cmd_list =
	TAILQ_HEAD_INITIALIZER(db_mach_cmd_list);
#ifdef DB_MACHINE_COMMANDS
static struct db_cmd_tbl_en db_mach_cmd_builtins =
     { .db_cmd = db_machine_command_table };
#endif

/*
 * if 'ed' style: 'dot' is set at start of last item printed,
 * and '+' points to next line.
 * Otherwise: 'dot' points to next item, '..' points to last.
 */
static bool	 db_ed_style = true;

static void	db_init_commands(void);
static int	db_register_tbl_entry(uint8_t type,
    struct db_cmd_tbl_en *list_ent);
static void	db_cmd_list(const struct db_cmd_tbl_en_head *);
static int	db_cmd_search(const char *, const struct db_command *,
    const struct db_command **);
static void	db_command(const struct db_command **);
static void	db_buf_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_event_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_fncall(db_expr_t, bool, db_expr_t, const char *);
static int      db_get_list_type(const char *);
static void     db_help_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_lock_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_mount_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_mbuf_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_malloc_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_map_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_namecache_print_cmd(db_expr_t, bool, db_expr_t,
		    const char *);
static void	db_object_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_page_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_show_all_pages(db_expr_t, bool, db_expr_t, const char *);
static void	db_pool_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_reboot_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_sifting_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_stack_trace_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_sync_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_uvmexp_print_cmd(db_expr_t, bool, db_expr_t, const char *);
static void	db_vnode_print_cmd(db_expr_t, bool, db_expr_t, const char *);

static const struct db_command db_show_cmds[] = {
	/*added from all sub cmds*/
	{ DDB_ADD_CMD("callout",  db_show_callout,
	    0 ,"List all used callout functions.",NULL,NULL) },
	{ DDB_ADD_CMD("pages",	db_show_all_pages,
	    0 ,"List all used memory pages.",NULL,NULL) },
	{ DDB_ADD_CMD("procs",	db_show_all_procs,
	    0 ,"List all processes.",NULL,NULL) },
	{ DDB_ADD_CMD("pools",	db_show_all_pools,
	    0 ,"Show all poolS",NULL,NULL) },
	/*added from all sub cmds*/
	{ DDB_ADD_CMD("aio_jobs",	db_show_aio_jobs,	0,
	    "Show aio jobs",NULL,NULL) },
	{ DDB_ADD_CMD("all",	NULL,
	    CS_COMPAT, NULL,NULL,NULL) },
#if defined(INET) && (NARP > 0)
	{ DDB_ADD_CMD("arptab",	db_show_arptab,		0,NULL,NULL,NULL) },
#endif
	{ DDB_ADD_CMD("breaks",	db_listbreak_cmd, 	0,
	    "Display all breaks.",NULL,NULL) },
	{ DDB_ADD_CMD("buf",	db_buf_print_cmd,	0,
	    "Print the struct buf at address.", "[/f] address",NULL) },
	{ DDB_ADD_CMD("event",	db_event_print_cmd,	0,
	    "Print all the non-zero evcnt(9) event counters.", "[/f]",NULL) },
	{ DDB_ADD_CMD("lock",	db_lock_print_cmd,	0,NULL,NULL,NULL) },
	{ DDB_ADD_CMD("malloc",	db_malloc_print_cmd,0,NULL,NULL,NULL) },
	{ DDB_ADD_CMD("map",	db_map_print_cmd,	0,
	    "Print the vm_map at address.", "[/f] address",NULL) },
	{ DDB_ADD_CMD("mount",	db_mount_print_cmd,	0,
	    "Print the mount structure at address.", "[/f] address",NULL) },
	{ DDB_ADD_CMD("mbuf",	db_mbuf_print_cmd,	0,NULL,NULL,
	    "-c prints all mbuf chains") },
	{ DDB_ADD_CMD("ncache",	db_namecache_print_cmd,	0,
	    "Dump the namecache list.", "address",NULL) },
	{ DDB_ADD_CMD("object",	db_object_print_cmd,	0,
	    "Print the vm_object at address.", "[/f] address",NULL) },
	{ DDB_ADD_CMD("page",	db_page_print_cmd,	0,
	    "Print the vm_page at address.", "[/f] address",NULL) },
	{ DDB_ADD_CMD("pool",	db_pool_print_cmd,	0,
	    "Print the pool at address.", "[/clp] address",NULL) },
	{ DDB_ADD_CMD("registers",	db_show_regs,		0,
	    "Display the register set.", "[/u]",NULL) },
	{ DDB_ADD_CMD("sched_qs",	db_show_sched_qs,	0,
	    "Print the state of the scheduler's run queues.",
	    NULL,NULL) },
	{ DDB_ADD_CMD("uvmexp",	db_uvmexp_print_cmd, 0,
	    "Print a selection of UVM counters and statistics.",
	    NULL,NULL) },
	{ DDB_ADD_CMD("vnode",	db_vnode_print_cmd,	0,
	    "Print the vnode at address.", "[/f] address",NULL) },
	{ DDB_ADD_CMD("watches",	db_listwatch_cmd, 	0,
	    "Display all watchpoints.", NULL,NULL) },
	{ DDB_ADD_CMD(NULL,		NULL,			0,NULL,NULL,NULL) }
};

/* arch/<arch>/<arch>/db_interface.c */
#ifdef DB_MACHINE_COMMANDS
extern const struct db_command db_machine_command_table[];
#endif

static const struct db_command db_command_table[] = {
	{ DDB_ADD_CMD("b",		db_breakpoint_cmd,	0,
	    "Set a breakpoint at address", "[/u] address[,count].",NULL) },
	{ DDB_ADD_CMD("break",	db_breakpoint_cmd,	0,
	    "Set a breakpoint at address", "[/u] address[,count].",NULL) },
	{ DDB_ADD_CMD("bt",		db_stack_trace_cmd,	0,
	    "Show backtrace.", "See help trace.",NULL) },
	{ DDB_ADD_CMD("c",		db_continue_cmd,	0,
	    "Continue execution.", "[/c]",NULL) },
	{ DDB_ADD_CMD("call",	db_fncall,		CS_OWN,
	    "Call the function", "address[(expression[,...])]",NULL) },
	{ DDB_ADD_CMD("callout",	db_show_callout,	0, NULL,
	    NULL,NULL ) },
	{ DDB_ADD_CMD("continue",	db_continue_cmd,	0,
	    "Continue execution.", "[/c]",NULL) },
	{ DDB_ADD_CMD("d",		db_delete_cmd,		0,
	    "Delete a breakpoint.", "address | #number",NULL) },
	{ DDB_ADD_CMD("delete",	db_delete_cmd,		0,
	    "Delete a breakpoint.", "address | #number",NULL) },
	{ DDB_ADD_CMD("dmesg",	db_dmesg,		0,
	    "Show kernel message buffer.", "[count]",NULL) },
	{ DDB_ADD_CMD("dwatch",	db_deletewatch_cmd,	0,
	    "Delete the watchpoint.", "address",NULL) },
	{ DDB_ADD_CMD("examine",	db_examine_cmd,		CS_SET_DOT,
	    "Display the address locations.",
	    "[/modifier] address[,count]",NULL) },
	{ DDB_ADD_CMD("help",   db_help_print_cmd, CS_OWN|CS_NOREPEAT,
	    "Display help about commands",
	    "Use other commands as arguments.",NULL) },
	{ DDB_ADD_CMD("kill",	db_kill_proc,		CS_OWN,
	    "Send a signal to the process","pid[,signal_number]",
	    "   pid:\t\t\tthe process id (may need 0t prefix for decimal)\n"
	    "   signal_number:\tthe signal to send") },
#ifdef KGDB
	{ DDB_ADD_CMD("kgdb",	db_kgdb_cmd,	0,	NULL,NULL,NULL) },
#endif
	{ DDB_ADD_CMD("machine",NULL,CS_MACH,
	    "Architecture specific functions.",NULL,NULL) },
	{ DDB_ADD_CMD("match",	db_trace_until_matching_cmd,0,
	    "Stop at the matching return instruction.","See help next",NULL) },
	{ DDB_ADD_CMD("next",	db_trace_until_matching_cmd,0,
	    "Stop at the matching return instruction.","[/p]",NULL) },
	{ DDB_ADD_CMD("p",		db_print_cmd,		0,
	    "Print address according to the format.",
	    "[/axzodurc] address [address ...]",NULL) },
	{ DDB_ADD_CMD("print",	db_print_cmd,		0,
	    "Print address according to the format.",
	    "[/axzodurc] address [address ...]",NULL) },
	{ DDB_ADD_CMD("ps",		db_show_all_procs,	0,
	    "Print all processes.","See show all procs",NULL) },
	{ DDB_ADD_CMD("reboot",	db_reboot_cmd,		CS_OWN,
	    "Reboot","0x1  RB_ASKNAME, 0x2 RB_SINGLE, 0x4 RB_NOSYNC, 0x8 RB_HALT,"
	    "0x40 RB_KDB, 0x100 RB_DUMP, 0x808 RB_POWERDOWN",NULL) },
	{ DDB_ADD_CMD("s",		db_single_step_cmd,	0,
	    "Single-step count times.","[/p] [,count]",NULL) },
	{ DDB_ADD_CMD("search",	db_search_cmd,		CS_OWN|CS_SET_DOT,
	    "Search memory from address for value.",
	    "[/bhl] address value [mask] [,count]",NULL) },
	{ DDB_ADD_CMD("set",	db_set_cmd,		CS_OWN,
	    "Set the named variable","$variable [=] expression",NULL) },
	{ DDB_ADD_CMD("show",	NULL, CS_SHOW,
	    "Show kernel stats.", NULL,NULL) },
	{ DDB_ADD_CMD("sifting",	db_sifting_cmd,		CS_OWN,
	    "Search the symbol tables ","[/F] string",NULL) },
	{ DDB_ADD_CMD("step",	db_single_step_cmd,	0,
	    "Single-step count times.","[/p] [,count]",NULL) },
	{ DDB_ADD_CMD("sync",	db_sync_cmd,		CS_OWN,
	    "Force a crash dump, and then reboot.",NULL,NULL) },
	{ DDB_ADD_CMD("trace",	db_stack_trace_cmd,	0,
	    "Stack trace from frame-address.",
	    "[/u[l]] [frame-address][,count]",NULL) },
	{ DDB_ADD_CMD("until",	db_trace_until_call_cmd,0,
	    "Stop at the next call or return instruction.","[/p]",NULL) },
	{ DDB_ADD_CMD("w",		db_write_cmd,		CS_MORE|CS_SET_DOT,
	    "Set a watchpoint for a region. ","address[,size]",NULL) },
	{ DDB_ADD_CMD("watch",	db_watchpoint_cmd,	CS_MORE,
	    "Set a watchpoint for a region. ","address[,size]",NULL) },
	{ DDB_ADD_CMD("write",	db_write_cmd,		CS_MORE|CS_SET_DOT,
	    "Write the expressions at succeeding locations.",
	    "[/bhl] address expression [expression ...]",NULL) },
	{ DDB_ADD_CMD("x",		db_examine_cmd,		CS_SET_DOT,
	    "Display the address locations.",
	    "[/modifier] address[,count]",NULL) },
	{ DDB_ADD_CMD(NULL, 	NULL,		   0, NULL, NULL, NULL) }
};

static const struct db_command	*db_last_command = NULL;
#if defined(DDB_COMMANDONENTER)
char db_cmd_on_enter[DB_LINE_MAXLEN + 1] = ___STRING(DDB_COMMANDONENTER);
#else /* defined(DDB_COMMANDONENTER) */
char db_cmd_on_enter[DB_LINE_MAXLEN + 1] = "";
#endif /* defined(DDB_COMMANDONENTER) */
#define	DB_LINE_SEP	';'

/*
 * Utility routine - discard tokens through end-of-line.
 */
void
db_skip_to_eol(void)
{
	int t;

	do {
		t = db_read_token();
	} while (t != tEOL);
}

void
db_error(const char *s)
{

	if (s)
		db_printf("%s", s);
	db_flush_lex();
	longjmp(db_recover);
}

/*Execute commandlist after ddb start
 *This function goes through the command list created from commands and ';'
 */

static void
db_execute_commandlist(const char *cmdlist)
{
	const char *cmd = cmdlist;
	const struct db_command	*dummy = NULL;

	while (*cmd != '\0') {
		const char *ep = cmd;

		while (*ep != '\0' && *ep != DB_LINE_SEP) {
			ep++;
		}
		db_set_line(cmd, ep);
		db_command(&dummy);
		cmd = ep;
		if (*cmd == DB_LINE_SEP) {
			cmd++;
		}
	}
}

/*Initialize ddb command tables*/
void
db_init_commands(void)
{
	static bool done = false;

	if (done) return;
	done = true;

	/* register command tables */
	(void)db_register_tbl_entry(DDB_BASE_CMD, &db_base_cmd_builtins);
#ifdef DB_MACHINE_COMMANDS
	(void)db_register_tbl_entry(DDB_MACH_CMD, &db_mach_cmd_builtins);
#endif
	(void)db_register_tbl_entry(DDB_SHOW_CMD, &db_show_cmd_builtins);
}


/*
 * Add command table to the specified list
 * Arg:
 * int type specifies type of command table DDB_SHOW_CMD|DDB_BASE_CMD|DDB_MAC_CMD
 * *cmd_tbl poiter to static allocated db_command table
 *
 *Command table must be NULL terminated array of struct db_command
 */
int
db_register_tbl(uint8_t type, const struct db_command *cmd_tbl)
{
	struct db_cmd_tbl_en *list_ent;

	if (cmd_tbl->name == 0)
		/* empty list - ignore */
		return 0;

	/* force builtin commands to be registered first */
	db_init_commands();

	/* now create a list entry for this table */
	list_ent = malloc(sizeof(struct db_cmd_tbl_en), M_TEMP, M_ZERO);
	if (list_ent == NULL)
		return ENOMEM;
	list_ent->db_cmd=cmd_tbl;

	/* and register it */
	return db_register_tbl_entry(type, list_ent);
}

static int
db_register_tbl_entry(uint8_t type, struct db_cmd_tbl_en *list_ent)
{
	struct db_cmd_tbl_en_head *list;

	switch(type) {
	case DDB_BASE_CMD:
		list = &db_base_cmd_list;
		break;
	case DDB_SHOW_CMD:
		list = &db_show_cmd_list;
		break;
	case DDB_MACH_CMD:
		list = &db_mach_cmd_list;
		break;
	default:
		return ENOENT;
	}

	TAILQ_INSERT_TAIL(list, list_ent, db_cmd_next);

	return 0;
}

/*
 * Remove command table specified with db_cmd address == cmd_tbl
 */
int
db_unregister_tbl(uint8_t type,const struct db_command *cmd_tbl)
{
	struct db_cmd_tbl_en *list_ent;
	struct db_cmd_tbl_en_head *list;

	/* find list on which the entry should live */
	switch (type) {
	case DDB_BASE_CMD:
		list=&db_base_cmd_list;
		break;
	case DDB_SHOW_CMD:
		list=&db_show_cmd_list;
		break;
	case DDB_MACH_CMD:
		list=&db_mach_cmd_list;
		break;
	default:
		return EINVAL;
	}

	TAILQ_FOREACH (list_ent,list,db_cmd_next) {
		if (list_ent->db_cmd == cmd_tbl){
			TAILQ_REMOVE(list,
			    list_ent,db_cmd_next);
			free(list_ent,M_TEMP);
			return 0;
		}
	}
	return ENOENT;
}

/*This function is called from machine trap code.*/
void
db_command_loop(void)
{

	label_t	db_jmpbuf;
	label_t	*savejmp;

	/*
	 * Initialize 'prev' and 'next' to dot.
	 */
	db_prev = db_dot;
	db_next = db_dot;

	db_cmd_loop_done = false;

	/*Init default command tables add machine, base,
	  show command tables to the list*/
	db_init_commands();

	/*save context for return from ddb*/
	savejmp = db_recover;
	db_recover = &db_jmpbuf;
	(void) setjmp(&db_jmpbuf);

	/*Execute default ddb start commands*/
	db_execute_commandlist(db_cmd_on_enter);

	(void) setjmp(&db_jmpbuf);
	while (!db_cmd_loop_done) {
		if (db_print_position() != 0)
			db_printf("\n");
		db_output_line = 0;


#ifdef MULTIPROCESSOR
		db_printf("db{%ld}> ", (long)cpu_number());
#else
		db_printf("db> ");
#endif
		(void) db_read_line();

		db_command(&db_last_command);
	}

	db_recover = savejmp;
}

/*
 * Search for command table for command prefix
 * ret: CMD_UNIQUE    -> completely matches command
 *      CMD_FOUND     -> matches prefix of single command
 *      CMD_AMBIGIOUS -> matches prefix of more than one command
 *      CMD_NONE      -> command not found
 */
static int
db_cmd_search(const char *name,const struct db_command *table,
    const struct db_command **cmdp)
{

	const struct db_command	*cmd;
	int result;

	result = CMD_NONE;
	for (cmd = table; cmd->name != 0; cmd++) {
		const char *lp;
		const char *rp;

		lp = name;
		rp = cmd->name;
		while (*lp != '\0' && *lp == *rp) {
			rp++;
			lp++;
		}

		if (*lp != '\0') /* mismatch or extra chars in name */
			continue;

		if (*rp == '\0') { /* complete match */
			*cmdp = cmd;
			return (CMD_UNIQUE);
		}

		/* prefix match: end of name, not end of command */
		if (result == CMD_NONE) {
			result = CMD_FOUND;
			*cmdp = cmd;
		}
		else if (result == CMD_FOUND) {
			result = CMD_AMBIGUOUS;
			*cmdp = NULL;
		}
	}

	return (result);
}

/*
 *List commands to the console.
 */
static void
db_cmd_list(const struct db_cmd_tbl_en_head *list)
{

	struct db_cmd_tbl_en *list_ent;
	const struct db_command *table;
	size_t		i, j, w, columns, lines, numcmds, width=0;
	const char	*p;

	TAILQ_FOREACH(list_ent,list,db_cmd_next) {
		table = list_ent->db_cmd;
		for (i = 0; table[i].name != NULL; i++) {
			w = strlen(table[i].name);
			if (w > width)
				width = w;
		}
	}

	width = DB_NEXT_TAB(width);

	columns = db_max_width / width;
	if (columns == 0)
		columns = 1;

	TAILQ_FOREACH(list_ent,list,db_cmd_next) {
		table = list_ent->db_cmd;

		for (numcmds = 0; table[numcmds].name != NULL; numcmds++)
			;
		lines = (numcmds + columns - 1) / columns;

		for (i = 0; i < lines; i++) {
			for (j = 0; j < columns; j++) {
				p = table[j * lines + i].name;
				if (p)
					db_printf("%s", p);
				if (j * lines + i + lines >= numcmds) {
					db_putchar('\n');
					break;
				}
				if (p) {
					w = strlen(p);
					while (w < width) {
						w = DB_NEXT_TAB(w);
						db_putchar('\t');
					}
				}
			}
		}
	}
	return;
}

/*
 *Returns type of list for command with name *name.
 */
static int
db_get_list_type(const char *name)
{

	const struct db_command    *cmd;
	struct db_cmd_tbl_en *list_ent;
	int error,ret=-1;

	/* search for the command name */
	TAILQ_FOREACH(list_ent,&db_base_cmd_list,db_cmd_next) {
		/*
		 * cmd_search returns CMD_UNIQUE, CMD_FOUND ...
		 * CMD_UNIQUE when name was completly matched to cmd->name
		 * CMD_FOUND  when name was only partially matched to cmd->name
		 * CMD_NONE   command not found in a list
		 * CMD_AMBIGIOUS ->more partialy matches
		 */

		error = db_cmd_search(name, list_ent->db_cmd, &cmd);

		if (error == CMD_UNIQUE) {
			/* exact match found */
			if (cmd->flag == CS_SHOW) {
				ret = DDB_SHOW_CMD;
				break;
			}
			if (cmd->flag == CS_MACH) {
				ret = DDB_MACH_CMD;
				break;
			} else {
				ret = DDB_BASE_CMD;
				break;
			}

		} else if (error == CMD_FOUND){
			/*
			 * partial match, search will continue, but
			 * note current result in case we won't
			 * find anything better.
			 */
			if (cmd->flag == CS_SHOW)
				ret = DDB_SHOW_CMD;
			if (cmd->flag == CS_MACH)
				ret = DDB_MACH_CMD;
			else
				ret = DDB_BASE_CMD;
		}
	}

	return ret;
}

/*
 *Parse command line and execute apropriate function.
 */
static void
db_command(const struct db_command **last_cmdp)
{
	const struct db_command *command;
	struct db_cmd_tbl_en *list_ent;
	struct db_cmd_tbl_en_head *list;

	int		t;
	int		result;

	char		modif[TOK_STRING_SIZE];
	db_expr_t	addr, count;
	bool		have_addr = false;

	static db_expr_t last_count = 0;

	command = NULL;	/* XXX gcc */

	t = db_read_token();
	if ((t == tEOL) || (t == tCOMMA)) {
		/*
		 * An empty line repeats last command, at 'next'.
		 * Only a count repeats the last command with the new count.
		 */
		command = *last_cmdp;

		if (!command)
			return;

		addr = (db_expr_t)db_next;
		if (t == tCOMMA) {
			if (!db_expression(&count)) {
				db_printf("Count missing\n");
				db_flush_lex();
				return;
			}
		} else
			count = last_count;
		have_addr = false;
		modif[0] = '\0';
		db_skip_to_eol();

	} else if (t == tEXCL) {
		db_fncall(0, 0, 0, NULL);
		return;

	} else if (t != tIDENT) {
		db_printf("?\n");
		db_flush_lex();
		return;

	} else {

		switch(db_get_list_type(db_tok_string)) {

		case DDB_BASE_CMD:
			list = &db_base_cmd_list;
			break;

		case DDB_SHOW_CMD:
			list = &db_show_cmd_list;
			/* need to read show subcommand if show command list
			   is used. */
			t = db_read_token();

			if (t != tIDENT) {
				/* if only show command is executed, print
				   all subcommands */
				db_cmd_list(list);
				db_flush_lex();
				return;
			}
			break;
		case DDB_MACH_CMD:
			list = &db_mach_cmd_list;
			/* need to read machine subcommand if
			  machine level 2 command list is used. */
			t = db_read_token();

			if (t != tIDENT) {
				/* if only show command is executed, print
				   all subcommands */
				db_cmd_list(list);
				db_flush_lex();
				return;
			}
			break;
		default:
			db_printf("No such command\n");
			db_flush_lex();
			return;
		}

 COMPAT_RET:
		TAILQ_FOREACH(list_ent, list, db_cmd_next) {
			result = db_cmd_search(db_tok_string, list_ent->db_cmd,
			    &command);

			/* after CMD_UNIQUE in cmd_list only a single command
			   name is possible */
			if (result == CMD_UNIQUE)
				break;

		}

                /* check compatibility flag */
		if (command && command->flag & CS_COMPAT){
			t = db_read_token();
			if (t != tIDENT) {
					db_cmd_list(list);
					db_flush_lex();
					return;
			}

			/* support only level 2 commands here */
			goto COMPAT_RET;
		}

		if (!command) {
			db_printf("No such command\n");
			db_flush_lex();
			return;
		}

		if ((command->flag & CS_OWN) == 0) {

			/*
			 * Standard syntax:
			 * command [/modifier] [addr] [,count]
			 */
			t = db_read_token(); /* get modifier */
			if (t == tSLASH) {
				t = db_read_token();
				if (t != tIDENT) {
					db_printf("Bad modifier\n");
					db_flush_lex();
					return;
				}
				/* save modifier */
				strlcpy(modif, db_tok_string, sizeof(modif));

			} else {
				db_unread_token(t);
				modif[0] = '\0';
			}

			if (db_expression(&addr)) { /*get address*/
				db_dot = (db_addr_t) addr;
				db_last_addr = db_dot;
				have_addr = true;
			} else {
				addr = (db_expr_t) db_dot;
				have_addr = false;
			}

			t = db_read_token();
			if (t == tCOMMA) { /*Get count*/
				if (!db_expression(&count)) {
					db_printf("Count missing\n");
					db_flush_lex();
					return;
				}
			} else {
				db_unread_token(t);
				count = -1;
			}
			if ((command->flag & CS_MORE) == 0) {
				db_skip_to_eol();
			}
		}
	}

	if (command->flag & CS_NOREPEAT) {
		*last_cmdp = NULL;
		last_count = 0;
	} else {
		*last_cmdp = command;
		last_count = count;
	}

	if (command != NULL) {
		/*
		 * Execute the command.
		 */
		if (command->fcn != NULL)
			(*command->fcn)(addr, have_addr, count, modif);

		if (command->flag & CS_SET_DOT) {
			/*
			 * If command changes dot, set dot to
			 * previous address displayed (if 'ed' style).
			 */
			if (db_ed_style)
				db_dot = db_prev;
			else
				db_dot = db_next;
		} else {
			/*
			 * If command does not change dot,
			 * set 'next' location to be the same.
			 */
			db_next = db_dot;
		}
	}
}

/*
 * Print help for commands
 */
static void
db_help_print_cmd(db_expr_t addr, bool have_addr, db_expr_t count,
    const char *modif)
{

	const struct db_cmd_tbl_en_head *list;
	const struct db_cmd_tbl_en *list_ent;
	const struct db_command *help;
	int t, result;

	t = db_read_token();
	/* is there another command after the "help"? */
	if (t == tIDENT){

		switch(db_get_list_type(db_tok_string)){

		case DDB_BASE_CMD:
			list=&db_base_cmd_list;
			break;
		case DDB_SHOW_CMD:
			list=&db_show_cmd_list;
			/* read the show subcommand */
			t = db_read_token();

			if (t != tIDENT) {
				/* no subcommand, print the list */
				db_cmd_list(list);
				db_flush_lex();
				return;
			}

			break;
		case DDB_MACH_CMD:
			list=&db_mach_cmd_list;
			/* read machine subcommand */
			t = db_read_token();

			if (t != tIDENT) {
				/* no subcommand - just print the list */
				db_cmd_list(list);
				db_flush_lex();
				return;
			}
			break;

		default:
			db_printf("No such command\n");
			db_flush_lex();
			return;
		}
 COMPAT_RET:
		TAILQ_FOREACH(list_ent,list,db_cmd_next){
			result = db_cmd_search(db_tok_string, list_ent->db_cmd,
					&help);
			/* after CMD_UNIQUE only a single command
			   name is possible */
			if (result == CMD_UNIQUE)
				break;
		}
#ifdef DDB_VERBOSE_HELP
		/*print help*/

		db_printf("Command: %s\n",help->name);

		if (help->cmd_descr != NULL)
			db_printf(" Description: %s\n",help->cmd_descr);

		if (help->cmd_arg != NULL)
			db_printf(" Arguments: %s\n",help->cmd_arg);

		if (help->cmd_arg_help != NULL)
			db_printf(" Arguments description:\n%s\n",
			    help->cmd_arg_help);

		if ((help->cmd_arg == NULL) && (help->cmd_descr == NULL))
			db_printf("%s Doesn't have any help message included.\n",
			    help->name);
#endif
		/* check compatibility flag */
		/*
		 * The "show all" command table has been merged with the
		 * "show" command table - but we want to keep the old UI
		 * available. So if we find a CS_COMPAT entry, we read
		 * the next token and try again.
		 */
		if (help->flag == CS_COMPAT){
			t = db_read_token();

			if (t != tIDENT){
				db_cmd_list(list);
				db_flush_lex();
				return;
			}

			goto COMPAT_RET;
			/* support only level 2 commands here */
		} else {
			db_skip_to_eol();
		}

	} else /* t != tIDENT */
		/* print base commands */
		db_cmd_list(&db_base_cmd_list);

	return;
}
/*ARGSUSED*/
static void
db_map_print_cmd(db_expr_t addr, bool have_addr, db_expr_t count,
    const char *modif)
{
	bool full = false;

	if (modif[0] == 'f')
		full = true;

	if (have_addr == false)
		addr = (db_expr_t)(intptr_t) kernel_map;

	uvm_map_printit((struct vm_map *)(intptr_t) addr, full, db_printf);
}

/*ARGSUSED*/
static void
db_malloc_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{

#ifdef MALLOC_DEBUG
	if (!have_addr)
		addr = 0;

	debug_malloc_printit(db_printf, (vaddr_t) addr);
#else
	db_printf("The kernel is not built with the MALLOC_DEBUG option.\n");
#endif /* MALLOC_DEBUG */
}

/*ARGSUSED*/
static void
db_object_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
	bool full = false;

	if (modif[0] == 'f')
		full = true;

	uvm_object_printit((struct uvm_object *)(intptr_t) addr, full,
	    db_printf);
}

/*ARGSUSED*/
static void
db_page_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
	bool full = false;

	if (modif[0] == 'f')
		full = true;

	uvm_page_printit((struct vm_page *)(intptr_t) addr, full, db_printf);
}

/*ARGSUSED*/
static void
db_show_all_pages(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{

	uvm_page_printall(db_printf);
}

/*ARGSUSED*/
static void
db_buf_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
	bool full = false;

	if (modif[0] == 'f')
		full = true;

	vfs_buf_print((struct buf *)(intptr_t) addr, full, db_printf);
}

/*ARGSUSED*/
static void
db_event_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
	bool full = false;

	if (modif[0] == 'f')
		full = true;

	event_print(full, db_printf);
}

/*ARGSUSED*/
static void
db_vnode_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
	bool full = false;

	if (modif[0] == 'f')
		full = true;

	vfs_vnode_print((struct vnode *)(intptr_t) addr, full, db_printf);
}

static void
db_mount_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
	bool full = false;

	if (modif[0] == 'f')
		full = true;

	vfs_mount_print((struct mount *)(intptr_t) addr, full, db_printf);
}

/*ARGSUSED*/
static void
db_mbuf_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{

	m_print((const struct mbuf *)(intptr_t) addr, modif, db_printf);
}

/*ARGSUSED*/
static void
db_pool_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{

	pool_printit((struct pool *)(intptr_t) addr, modif, db_printf);
}

/*ARGSUSED*/
static void
db_namecache_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{

	namecache_print((struct vnode *)(intptr_t) addr, db_printf);
}

/*ARGSUSED*/
static void
db_uvmexp_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{

	uvmexp_print(db_printf);
}

/*ARGSUSED*/
static void
db_lock_print_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{

	lockdebug_lock_print((void *)addr, db_printf);
}

/*
 * Call random function:
 * !expr(arg,arg,arg)
 */
/*ARGSUSED*/
static void
db_fncall(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
	db_expr_t	fn_addr;
#define	MAXARGS		11
	db_expr_t	args[MAXARGS];
	int		nargs = 0;
	db_expr_t	retval;
	db_expr_t	(*func)(db_expr_t, ...);
	int		t;

	if (!db_expression(&fn_addr)) {
		db_printf("Bad function\n");
		db_flush_lex();
		return;
	}
	func = (db_expr_t (*)(db_expr_t, ...))(intptr_t) fn_addr;

	t = db_read_token();
	if (t == tLPAREN) {
		if (db_expression(&args[0])) {
			nargs++;
			while ((t = db_read_token()) == tCOMMA) {
				if (nargs == MAXARGS) {
					db_printf("Too many arguments\n");
					db_flush_lex();
					return;
				}
				if (!db_expression(&args[nargs])) {
					db_printf("Argument missing\n");
					db_flush_lex();
					return;
				}
				nargs++;
			}
			db_unread_token(t);
		}
		if (db_read_token() != tRPAREN) {
			db_printf("?\n");
			db_flush_lex();
			return;
		}
	}
	db_skip_to_eol();

	while (nargs < MAXARGS) {
		args[nargs++] = 0;
	}

	retval = (*func)(args[0], args[1], args[2], args[3], args[4],
			 args[5], args[6], args[7], args[8], args[9]);
	db_printf("%s\n", db_num_to_str(retval));
}

static void
db_reboot_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
	db_expr_t bootflags;

	/* Flags, default to RB_AUTOBOOT */
	if (!db_expression(&bootflags))
		bootflags = (db_expr_t)RB_AUTOBOOT;
	if (db_read_token() != tEOL) {
		db_error("?\n");
		/*NOTREACHED*/
	}
	/*
	 * We are leaving DDB, never to return upward.
	 * Clear db_recover so that we can debug faults in functions
	 * called from cpu_reboot.
	 */
	db_recover = 0;
	cpu_reboot((int)bootflags, NULL);
}

static void
db_sifting_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
	int	mode, t;

	t = db_read_token();
	if (t == tSLASH) {
		t = db_read_token();
		if (t != tIDENT) {
			bad_modifier:
			db_printf("Bad modifier\n");
			db_flush_lex();
			return;
		}
		if (!strcmp(db_tok_string, "F"))
			mode = 'F';
		else
			goto bad_modifier;
		t = db_read_token();
	} else
		mode = 0;

	if (t == tIDENT)
		db_sifting(db_tok_string, mode);
	else {
		db_printf("Bad argument (non-string)\n");
		db_flush_lex();
	}
}

static void
db_stack_trace_cmd(db_expr_t addr, bool have_addr, db_expr_t count, const char *modif)
{
	register const char *cp = modif;
	register char c;
	void (*pr)(const char *, ...);

	pr = db_printf;
	while ((c = *cp++) != 0)
		if (c == 'l')
			pr = printf;

	if (count == -1)
		count = 65535;

	db_stack_trace_print(addr, have_addr, count, modif, pr);
}

static void
db_sync_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{

	/*
	 * We are leaving DDB, never to return upward.
	 * Clear db_recover so that we can debug faults in functions
	 * called from cpu_reboot.
	 */
	db_recover = 0;
	cpu_reboot(RB_DUMP, NULL);
}