FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_debug.c

     /*      $NetBSD: subr_debug.c,v 1.7 2008/04/30 20:20:53 ad Exp $        */
     
     /*-
      * Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Andrew Doran.
      *
     * 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.
     *
     * 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.
     */
    
    /*
     * Shared support code for kernels built with the DEBUG option.
     */
     
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: subr_debug.c,v 1.7 2008/04/30 20:20:53 ad Exp $");
    
    #include "opt_ddb.h"
    
    #include <sys/param.h>
    #include <sys/proc.h>
    #include <sys/systm.h>
    #include <sys/kmem.h>
    #include <sys/debug.h>
    #include <sys/atomic.h>
    #include <sys/cpu.h>
    
    #include <uvm/uvm_extern.h>
    
    #include <machine/lock.h>
    
    /*
     * Allocation/free validation by pointer address.  Introduces
     * significant overhead and is not enabled by default.  Patch
     * `debug_freecheck' to 1 at boot time to enable.
     */
    #define FREECHECK_BYTES         (8*1024*1024)
    
    typedef struct fcitem {
            void            *i_addr;
            struct fcitem   *i_next;
    } fcitem_t;
    
    fcitem_t                *freecheck_free;
    __cpu_simple_lock_t     freecheck_lock;
    u_int                   debug_freecheck;
    
    void
    debug_init(void)
    {
            size_t cnt;
            fcitem_t *i;
    
            __cpu_simple_lock_init(&freecheck_lock);
    
            if (debug_freecheck) {
                    i = (fcitem_t *)uvm_km_alloc(kernel_map, FREECHECK_BYTES, 0,
                        UVM_KMF_WIRED);
                    if (i == NULL) {
                            printf("freecheck_init: unable to allocate memory");
                            return;
                    }
    
                    for (cnt = FREECHECK_BYTES / sizeof(*i); cnt != 0; cnt--) {
                            i->i_next = freecheck_free;
                            freecheck_free = i++;
                    }
            }
    }
    
    void
    freecheck_out(void **head, void *addr)
    {
            fcitem_t *i;
            int s;
    
            if (!debug_freecheck)
                    return;
   
           s = splvm();
           __cpu_simple_lock(&freecheck_lock);
           for (i = *head; i != NULL; i = i->i_next) {
                   if (i->i_addr != addr)
                           continue;
                   __cpu_simple_unlock(&freecheck_lock);
                   splx(s);
                   panic("freecheck_out: %p already out", addr);
           }
           if ((i = freecheck_free) != NULL) {
                   freecheck_free = i->i_next;
                   i->i_addr = addr;
                   i->i_next = *head;
                   *head = i;
           }
           __cpu_simple_unlock(&freecheck_lock);
           splx(s);
   
           if (i == NULL) {
                   if (atomic_swap_uint(&debug_freecheck, 1) == 0)
                           printf("freecheck_out: no more slots\n");
           }
   }
   
   void
   freecheck_in(void **head, void *addr)
   {
           fcitem_t *i;
           void *pp;
           int s;
   
           if (!debug_freecheck)
                   return;
   
           s = splvm();
           __cpu_simple_lock(&freecheck_lock);
           for (i = *head, pp = head; i != NULL; pp = &i->i_next, i = i->i_next) {
                   if (i->i_addr == addr) {
                           *(fcitem_t **)pp = i->i_next;
                           i->i_next = freecheck_free;
                           freecheck_free = i;
                           break;
                   }
           }
           __cpu_simple_unlock(&freecheck_lock);
           splx(s);
   
           if (i != NULL)
                   return;
   
   #ifdef DDB
           printf("freecheck_in: %p not out\n", addr);
           Debugger();
   #else
           panic("freecheck_in: %p not out", addr);
   #endif
   }

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