1/*	$NetBSD: subr_debug.c,v 1.6 2008/04/28 20:24:04 martin Exp $	*/
2
3/*-
4 * Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Andrew Doran.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32/*
33 * Shared support code for kernels built with the DEBUG option.
34 */
35
36#include <sys/cdefs.h>
37__KERNEL_RCSID(0, "$NetBSD: subr_debug.c,v 1.6 2008/04/28 20:24:04 martin Exp $");
38
39#include "opt_ddb.h"
40
41#include <sys/param.h>
42#include <sys/proc.h>
43#include <sys/systm.h>
44#include <sys/kmem.h>
45#include <sys/debug.h>
46#include <sys/atomic.h>
47#include <sys/cpu.h>
48
49#include <uvm/uvm_extern.h>
50
51#include <machine/lock.h>
52
53/*
54 * Allocation/free validation by pointer address.  Introduces
55 * significant overhead and is not enabled by default.  Patch
56 * `debug_freecheck' to 1 at boot time to enable.
57 */
58#define	FREECHECK_BYTES		(8*1024*1024)
59
60typedef struct fcitem {
61	void		*i_addr;
62	struct fcitem	*i_next;
63} fcitem_t;
64
65fcitem_t		*freecheck_free;
66__cpu_simple_lock_t	freecheck_lock;
67u_int			debug_freecheck;
68
69void
70debug_init(void)
71{
72	size_t cnt;
73	fcitem_t *i;
74
75	__cpu_simple_lock_init(&freecheck_lock);
76
77	if (debug_freecheck) {
78		i = (fcitem_t *)uvm_km_alloc(kernel_map, FREECHECK_BYTES, 0,
79		    UVM_KMF_WIRED);
80		if (i == NULL) {
81			printf("freecheck_init: unable to allocate memory");
82			return;
83		}
84
85		for (cnt = FREECHECK_BYTES / sizeof(*i); cnt != 0; cnt--) {
86			i->i_next = freecheck_free;
87			freecheck_free = i++;
88		}
89	}
90}
91
92void
93freecheck_out(void **head, void *addr)
94{
95	fcitem_t *i;
96	int s;
97
98	if (!debug_freecheck)
99		return;
100
101	s = splvm();
102	__cpu_simple_lock(&freecheck_lock);
103	for (i = *head; i != NULL; i = i->i_next) {
104		if (i->i_addr != addr)
105			continue;
106		__cpu_simple_unlock(&freecheck_lock);
107		splx(s);
108		panic("freecheck_out: %p already out", addr);
109	}
110	if ((i = freecheck_free) != NULL) {
111		freecheck_free = i->i_next;
112		i->i_addr = addr;
113		i->i_next = *head;
114		*head = i;
115	}
116	__cpu_simple_unlock(&freecheck_lock);
117	splx(s);
118
119	if (i == NULL) {
120		if (atomic_swap_uint(&debug_freecheck, 1) == 0)
121			printf("freecheck_out: no more slots\n");
122	}
123}
124
125void
126freecheck_in(void **head, void *addr)
127{
128	fcitem_t *i;
129	void *pp;
130	int s;
131
132	if (!debug_freecheck)
133		return;
134
135	s = splvm();
136	__cpu_simple_lock(&freecheck_lock);
137	for (i = *head, pp = head; i != NULL; pp = &i->i_next, i = i->i_next) {
138		if (i->i_addr == addr) {
139			*(fcitem_t **)pp = i->i_next;
140			i->i_next = freecheck_free;
141			freecheck_free = i;
142			break;
143		}
144	}
145	__cpu_simple_unlock(&freecheck_lock);
146	splx(s);
147
148	if (i != NULL)
149		return;
150
151#ifdef DDB
152	printf("freecheck_in: %p not out\n", addr);
153	Debugger();
154#else
155	panic("freecheck_in: %p not out", addr);
156#endif
157}
158