sys/kern/subr_debug.c

   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
  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 }