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subr_debug.c revision 1.5.14.1 
      1 /*	$NetBSD: subr_debug.c,v 1.5.14.1 2008/06/02 13:24:10 mjf 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 1.5.14.1 2008/06/02 13:24:10 mjf 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 
     60 typedef struct fcitem {
     61 	void		*i_addr;
     62 	struct fcitem	*i_next;
     63 } fcitem_t;
     64 
     65 fcitem_t		*freecheck_free;
     66 __cpu_simple_lock_t	freecheck_lock;
     67 u_int			debug_freecheck;
     68 
     69 void
     70 debug_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 
     92 void
     93 freecheck_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 
    125 void
    126 freecheck_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