/*      $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
}