[apple/xnu.git] / osfmk / kern / ipc_kobject.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */
/*
 *      File:   kern/ipc_kobject.c
 *      Author: Rich Draves
 *      Date:   1989
 *
 *      Functions for letting a port represent a kernel object.
 */

#include <mach_debug.h>
#include <mach_ipc_test.h>
#include <mach_machine_routines.h>
#include <norma_task.h>
#include <mach_rt.h>
#include <platforms.h>

#include <kern/ast.h>
#include <mach/port.h>
#include <mach/kern_return.h>
#include <mach/message.h>
#include <mach/mig_errors.h>
#include <mach/notify.h>
#include <kern/etap_macros.h>
#include <kern/ipc_mig.h>
#include <kern/ipc_kobject.h>
#include <kern/misc_protos.h>
#include <kern/mk_timer.h>
#include <ipc/ipc_object.h>
#include <ipc/ipc_kmsg.h>
#include <ipc/ipc_port.h>
#include <kern/counters.h>


void
                 def_pager_hash_insert(
                                ipc_port_t name_port);
void             pager_mux_hash_insert(
                                ipc_port_t              port,
                                rpc_subsystem_t         rec);
void             pager_mux_hash_delete(
                                ipc_port_t              port);
rpc_subsystem_t  pager_mux_hash_lookup(
                                ipc_port_t              port);


/*
 *      Routine:        ipc_kobject_notify
 *      Purpose:
 *              Deliver notifications to kobjects that care about them.
 */
boolean_t
ipc_kobject_notify(
        mach_msg_header_t *request_header,
        mach_msg_header_t *reply_header);

#include <mach/ndr.h>

typedef struct {
        mach_msg_id_t num;
        mig_routine_t routine;
        int size;
#if     MACH_COUNTERS
        mach_counter_t callcount;
#endif
} mig_hash_t;

#define MAX_MIG_ENTRIES 1024
#define MIG_HASH(x) (x)

#ifndef max
#define max(a,b)        (((a) > (b)) ? (a) : (b))
#endif /* max */

mig_hash_t mig_buckets[MAX_MIG_ENTRIES];
int mig_table_max_displ;
mach_msg_size_t mig_reply_size;


#include <mach/mach_port_server.h>
#include <mach/mach_host_server.h>
#include <mach/host_priv_server.h>
#include <mach/host_security_server.h>
#include <mach/clock_server.h>
#include <mach/clock_priv_server.h>
#include <mach/ledger_server.h>
#include <mach/lock_set_server.h>
#include <default_pager/default_pager_object_server.h>
#include <mach/memory_object_server.h>
#include <mach/memory_object_control_server.h>
#include <mach/memory_object_default_server.h>
#include <mach/memory_object_name_server.h>
#include <mach/processor_server.h>
#include <mach/processor_set_server.h>
#include <mach/semaphore_server.h>
#include <mach/task_server.h>
#include <mach/vm_map_server.h>
#include <mach/thread_act_server.h>
#include <device/device_server.h>
#include <UserNotification/UNDReplyServer.h>

#if     MACH_MACHINE_ROUTINES
#include <machine/machine_routines.h>
#endif  /* MACH_MACHINE_ROUTINES */
#if     XK_PROXY
#include <uk_xkern/xk_uproxy_server.h>
#endif  /* XK_PROXY */


rpc_subsystem_t mig_e[] = {
        (rpc_subsystem_t)&mach_port_subsystem,
        (rpc_subsystem_t)&mach_host_subsystem,
        (rpc_subsystem_t)&host_priv_subsystem,
        (rpc_subsystem_t)&host_security_subsystem,
        (rpc_subsystem_t)&clock_subsystem,
        (rpc_subsystem_t)&clock_priv_subsystem,
        (rpc_subsystem_t)&processor_subsystem,
        (rpc_subsystem_t)&processor_set_subsystem,
        (rpc_subsystem_t)&is_iokit_subsystem,
        (rpc_subsystem_t)&dp_memory_object_subsystem,
        (rpc_subsystem_t)&dp_memory_object_default_subsystem,
        (rpc_subsystem_t)&memory_object_name_subsystem,
        (rpc_subsystem_t)&default_pager_object_subsystem,
        (rpc_subsystem_t)&lock_set_subsystem,
        (rpc_subsystem_t)&ledger_subsystem,
        (rpc_subsystem_t)&semaphore_subsystem,
        (rpc_subsystem_t)&task_subsystem,
        (rpc_subsystem_t)&thread_act_subsystem,
        (rpc_subsystem_t)&vm_map_subsystem,
        (rpc_subsystem_t)&UNDReply_subsystem,

#if     XK_PROXY
        (rpc_subsystem_t)&do_uproxy_xk_uproxy_subsystem,
#endif /* XK_PROXY */
#if     MACH_MACHINE_ROUTINES
        (rpc_subsystem_t)&MACHINE_SUBSYSTEM,
#endif  /* MACH_MACHINE_ROUTINES */
#if     MCMSG && iPSC860
        (rpc_subsystem_t)&mcmsg_info_subsystem,
#endif  /* MCMSG && iPSC860 */
};

void
mig_init(void)
{
    register unsigned int i, n = sizeof(mig_e)/sizeof(rpc_subsystem_t);
    register unsigned int howmany;
    register mach_msg_id_t j, pos, nentry, range;
        
    for (i = 0; i < n; i++) {
        range = mig_e[i]->end - mig_e[i]->start;
        if (!mig_e[i]->start || range < 0)
            panic("the msgh_ids in mig_e[] aren't valid!");
        mig_reply_size = max(mig_reply_size, mig_e[i]->maxsize);

        for  (j = 0; j < range; j++) {
          if (mig_e[i]->routine[j].stub_routine) { 
            /* Only put real entries in the table */
            nentry = j + mig_e[i]->start;       
            for (pos = MIG_HASH(nentry) % MAX_MIG_ENTRIES, howmany = 1;
                 mig_buckets[pos].num;
                 pos = ++pos % MAX_MIG_ENTRIES, howmany++) {
                 if (mig_buckets[pos].num == nentry) {
                        printf("message id = %d\n", nentry);
                        panic("multiple entries with the same msgh_id");
                 }
                 if (howmany == MAX_MIG_ENTRIES)
                       panic("the mig dispatch table is too small");
            }
                
            mig_buckets[pos].num = nentry;
            mig_buckets[pos].routine = mig_e[i]->routine[j].stub_routine;
            if (mig_e[i]->routine[j].max_reply_msg)
                    mig_buckets[pos].size = mig_e[i]->routine[j].max_reply_msg;
            else
                    mig_buckets[pos].size = mig_e[i]->maxsize;

            mig_table_max_displ = max(howmany, mig_table_max_displ);
          }
        }
    }
}


#define PAGER_MUX_HASH_COUNT 127


struct pager_mux_entry {
        queue_chain_t   links;
        ipc_port_t      name;
        rpc_subsystem_t pager_object;
};
typedef struct pager_mux_entry *pager_mux_entry_t;

queue_head_t    pager_mux_hashtable[PAGER_MUX_HASH_COUNT];
zone_t          pager_mux_hash_zone;

decl_mutex_data(,pager_mux_hash_lock)

#define pager_mux_hash(name_port) \
                (((natural_t)(name_port) & 0xffffff) % PAGER_MUX_HASH_COUNT)


rpc_subsystem_t
pager_mux_hash_lookup(
        ipc_port_t      name_port)
{
        register queue_t        bucket;
        register pager_mux_entry_t      entry;
        register rpc_subsystem_t        pager_object;

        bucket = &pager_mux_hashtable[pager_mux_hash(name_port)];

        mutex_lock(&pager_mux_hash_lock);
        for (entry = (pager_mux_entry_t)queue_first(bucket);
             !queue_end(bucket, &entry->links);
             entry = (pager_mux_entry_t)queue_next(&entry->links)) {
            if (entry->name == name_port) {
                pager_object = entry->pager_object;
                /* don't need to reference the object, it can't disappear */
                /* pager_mux_reference(pager_object); */
                mutex_unlock(&pager_mux_hash_lock);
                return (pager_object);
            }
        }
        mutex_unlock(&pager_mux_hash_lock);
        return (rpc_subsystem_t)0;
}


void
pager_mux_hash_init(void)
{
        register int    i;
        register vm_size_t      size;

        size = sizeof(struct pager_mux_entry);
        pager_mux_hash_zone = zinit(
                                size,
                                size * 2000,
                                PAGE_SIZE,
                                "pager mux port hash");
        for (i = 0; i < PAGER_MUX_HASH_COUNT; i++)
            queue_init(&pager_mux_hashtable[i]);
        mutex_init(&pager_mux_hash_lock, ETAP_IO_DEV_PAGEH);
}


void
pager_mux_hash_insert(
        ipc_port_t      name_port,
        rpc_subsystem_t pager_object)
{
        register pager_mux_entry_t new_entry;

        new_entry = (pager_mux_entry_t) zalloc(pager_mux_hash_zone);
        new_entry->links.prev = (queue_entry_t) 0;
        new_entry->links.next = (queue_entry_t) 0;
        new_entry->name = name_port;
        new_entry->pager_object = pager_object;

        mutex_lock(&pager_mux_hash_lock);
        queue_enter((&pager_mux_hashtable[pager_mux_hash(name_port)]),
                        new_entry, pager_mux_entry_t, links);
        mutex_unlock(&pager_mux_hash_lock);
}

void
pager_mux_hash_delete(
        ipc_port_t      name_port)
{
        register queue_t        bucket;
        register pager_mux_entry_t      entry;

        bucket = &pager_mux_hashtable[pager_mux_hash(name_port)];

        mutex_lock(&pager_mux_hash_lock);
        for (entry = (pager_mux_entry_t)queue_first(bucket);
             !queue_end(bucket, &entry->links);
             entry = (pager_mux_entry_t)queue_next(&entry->links)) {
            if (entry->name == name_port) {
                queue_remove(bucket, entry, pager_mux_entry_t, links);
                zfree(pager_mux_hash_zone, (vm_offset_t)entry);
                break;
            }
        }
        mutex_unlock(&pager_mux_hash_lock);
}


/*
 *      Routine:        ipc_kobject_server
 *      Purpose:
 *              Handle a message sent to the kernel.
 *              Generates a reply message.
 *              Version for Untyped IPC.
 *      Conditions:
 *              Nothing locked.
 */

ipc_kmsg_t
ipc_kobject_server(
        ipc_kmsg_t      request)
{
        mach_msg_size_t reply_size;
        ipc_kmsg_t reply;
        kern_return_t kr;
        mig_routine_t routine;
        ipc_port_t *destp;
        mach_msg_format_0_trailer_t *trailer;
        register mig_hash_t *ptr;
        unsigned int th;

        /* Only fetch current thread if ETAP is configured */
        ETAP_DATA_LOAD(th, current_thread());
        ETAP_PROBE_DATA(ETAP_P_SYSCALL_MACH,
                        EVENT_BEGIN,
                        ((thread_t) th),
                        &request->ikm_header.msgh_id,
                        sizeof(int));
        /*
         * Find out corresponding mig_hash entry if any
         */
        {
            register int key = request->ikm_header.msgh_id;
            register int i = MIG_HASH(key);
            register int max_iter = mig_table_max_displ;
        
            do
                ptr = &mig_buckets[i++ % MAX_MIG_ENTRIES];
            while (key != ptr->num && ptr->num && --max_iter);

            if (!ptr->routine || key != ptr->num) {
                ptr = (mig_hash_t *)0;
                reply_size = mig_reply_size;
            } else {
                reply_size = ptr->size;
#if     MACH_COUNTER
                ptr->callcount++;
#endif
            }
        }

        /* round up for trailer size */
        reply_size += MAX_TRAILER_SIZE;
        reply = ipc_kmsg_alloc(reply_size);

        if (reply == IKM_NULL) {
                printf("ipc_kobject_server: dropping request\n");
                ipc_kmsg_destroy(request);
                return IKM_NULL;
        }

        /*
         * Initialize reply message.
         */
        {
#define InP     ((mach_msg_header_t *) &request->ikm_header)
#define OutP    ((mig_reply_error_t *) &reply->ikm_header)

            OutP->NDR = NDR_record;
            OutP->Head.msgh_size = sizeof(mig_reply_error_t);

            OutP->Head.msgh_bits =
                MACH_MSGH_BITS(MACH_MSGH_BITS_LOCAL(InP->msgh_bits), 0);
            OutP->Head.msgh_remote_port = InP->msgh_local_port;
            OutP->Head.msgh_local_port  = MACH_PORT_NULL;
            OutP->Head.msgh_id = InP->msgh_id + 100;

#undef  InP
#undef  OutP
        }

        /*
         * Find the routine to call, and call it
         * to perform the kernel function
         */
        {
            if (ptr) {  
                (*ptr->routine)(&request->ikm_header, &reply->ikm_header);
                kernel_task->messages_received++;
            }
            else {
                if (!ipc_kobject_notify(&request->ikm_header, &reply->ikm_header)){
#if     MACH_IPC_TEST
                    printf("ipc_kobject_server: bogus kernel message, id=%d\n",
                        request->ikm_header.msgh_id);
#endif  /* MACH_IPC_TEST */
                    _MIG_MSGID_INVALID(request->ikm_header.msgh_id);

                    ((mig_reply_error_t *) &reply->ikm_header)->RetCode
                        = MIG_BAD_ID;
                }
                else
                  kernel_task->messages_received++;
            }
            kernel_task->messages_sent++;
        }

        /*
         *      Destroy destination. The following code differs from
         *      ipc_object_destroy in that we release the send-once
         *      right instead of generating a send-once notification
         *      (which would bring us here again, creating a loop).
         *      It also differs in that we only expect send or
         *      send-once rights, never receive rights.
         *
         *      We set msgh_remote_port to IP_NULL so that the kmsg
         *      destroy routines don't try to destroy the port twice.
         */
        destp = (ipc_port_t *) &request->ikm_header.msgh_remote_port;
        switch (MACH_MSGH_BITS_REMOTE(request->ikm_header.msgh_bits)) {
                case MACH_MSG_TYPE_PORT_SEND:
                    ipc_port_release_send(*destp);
                    break;
                
                case MACH_MSG_TYPE_PORT_SEND_ONCE:
                    ipc_port_release_sonce(*destp);
                    break;
                
                default:
                    panic("ipc_object_destroy: strange destination rights");
        }
        *destp = IP_NULL;

        if (!(reply->ikm_header.msgh_bits & MACH_MSGH_BITS_COMPLEX) &&
           ((mig_reply_error_t *) &reply->ikm_header)->RetCode != KERN_SUCCESS)
                kr = ((mig_reply_error_t *) &reply->ikm_header)->RetCode;
        else
                kr = KERN_SUCCESS;

        if ((kr == KERN_SUCCESS) || (kr == MIG_NO_REPLY)) {
                /*
                 *      The server function is responsible for the contents
                 *      of the message.  The reply port right is moved
                 *      to the reply message, and we have deallocated
                 *      the destination port right, so we just need
                 *      to free the kmsg.
                 */
                ipc_kmsg_free(request);

        } else {
                /*
                 *      The message contents of the request are intact.
                 *      Destroy everthing except the reply port right,
                 *      which is needed in the reply message.
                 */
                request->ikm_header.msgh_local_port = MACH_PORT_NULL;
                ipc_kmsg_destroy(request);
        }

        if (kr == MIG_NO_REPLY) {
                /*
                 *      The server function will send a reply message
                 *      using the reply port right, which it has saved.
                 */

                ipc_kmsg_free(reply);

                ETAP_PROBE_DATA(ETAP_P_SYSCALL_MACH,
                                EVENT_END,
                                ((thread_t) th),
                                &request->ikm_header.msgh_id,
                                sizeof(int));

                return IKM_NULL;
        } else if (!IP_VALID((ipc_port_t)reply->ikm_header.msgh_remote_port)) {
                /*
                 *      Can't queue the reply message if the destination
                 *      (the reply port) isn't valid.
                 */

                ipc_kmsg_destroy(reply);

                ETAP_PROBE_DATA(ETAP_P_SYSCALL_MACH,
                                EVENT_END,
                                ((thread_t) th),
                                &request->ikm_header.msgh_id,
                                sizeof(int));

                return IKM_NULL;
        }

        trailer = (mach_msg_format_0_trailer_t *)
                ((vm_offset_t)&reply->ikm_header + (int)reply->ikm_header.msgh_size);                
        trailer->msgh_sender = KERNEL_SECURITY_TOKEN;
        trailer->msgh_trailer_type = MACH_MSG_TRAILER_FORMAT_0;
        trailer->msgh_trailer_size = MACH_MSG_TRAILER_MINIMUM_SIZE;

        ETAP_PROBE_DATA(ETAP_P_SYSCALL_MACH,
                        EVENT_END,
                        ((thread_t) th),
                        &request->ikm_header.msgh_id,
                        sizeof(int));

        return reply;
}

/*
 *      Routine:        ipc_kobject_set
 *      Purpose:
 *              Make a port represent a kernel object of the given type.
 *              The caller is responsible for handling refs for the
 *              kernel object, if necessary.
 *      Conditions:
 *              Nothing locked.  The port must be active if setting
 *              a kobject linkage.  Clearing a linkage is OK on an
 *              inactive port.
 */
void
ipc_kobject_set(
        ipc_port_t                      port,
        ipc_kobject_t           kobject,
        ipc_kobject_type_t      type)
{
        ip_lock(port);
        ipc_kobject_set_atomically(port, kobject, type);
        ip_unlock(port);
}

void
ipc_kobject_set_atomically(
        ipc_port_t                      port,
        ipc_kobject_t           kobject,
        ipc_kobject_type_t      type)
{
        assert(type == IKOT_NONE || ip_active(port));
#if     MACH_ASSERT
        port->ip_spares[2] = (port->ip_bits & IO_BITS_KOTYPE);
#endif  /* MACH_ASSERT */
        port->ip_bits = (port->ip_bits &~ IO_BITS_KOTYPE) | type;
        port->ip_kobject = kobject;
}

/*
 *      Routine:        ipc_kobject_destroy
 *      Purpose:
 *              Release any kernel object resources associated
 *              with the port, which is being destroyed.
 *
 *              This should only be needed when resources are
 *              associated with a user's port.  In the normal case,
 *              when the kernel is the receiver, the code calling
 *              ipc_port_dealloc_kernel should clean up the resources.
 *      Conditions:
 *              The port is not locked, but it is dead.
 */

void
ipc_kobject_destroy(
        ipc_port_t              port)
{
        switch (ip_kotype(port)) {

        case IKOT_TIMER:
                mk_timer_port_destroy(port);
                break;

        case IKOT_NAMED_ENTRY:
                mach_destroy_memory_entry(port);
                break;

        case IKOT_UPL:
                mach_destroy_upl(port);
                break;

        default:        /* XXX (bogon) */
                vm_object_destroy(port);
                break;
        }
}


extern int vnode_pager_workaround;

boolean_t
ipc_kobject_notify(
        mach_msg_header_t *request_header,
        mach_msg_header_t *reply_header)
{
        ipc_port_t port = (ipc_port_t) request_header->msgh_remote_port;
        rpc_subsystem_t         paging_subsystem_object;
        mach_port_seqno_t       seqno;

        ((mig_reply_error_t *) reply_header)->RetCode = MIG_NO_REPLY;
        switch (request_header->msgh_id) {
                case MACH_NOTIFY_NO_SENDERS:
                   if(ip_kotype(port) == IKOT_NAMED_ENTRY) {
                        ip_lock(port);

                        /*
                         * Bring the sequence number and mscount in
                         * line with ipc_port_destroy assertion.
                         */
                        port->ip_mscount = 0;
                        port->ip_messages.imq_seqno = 0;
                        ipc_port_destroy(port); /* releases lock */
                        return TRUE;
                   }
                   paging_subsystem_object = pager_mux_hash_lookup(
                                (ipc_port_t)request_header->msgh_remote_port);
                   if(paging_subsystem_object == (rpc_subsystem_t)
                                        &dp_memory_object_subsystem) {
                      default_pager_no_senders(
                         (ipc_port_t)request_header->msgh_remote_port, 
                         seqno, 
                         (mach_port_mscount_t) 
                         ((mach_no_senders_notification_t *) 
                         request_header)->not_count);
                      (ipc_port_t)reply_header->msgh_remote_port
                          = MACH_PORT_NULL;
                      return TRUE;
                   }
                   if(paging_subsystem_object == (rpc_subsystem_t)
                                        &vnode_pager_workaround) {
                      vnode_pager_no_senders(
                         (ipc_port_t)request_header->msgh_remote_port, 
                         (mach_port_mscount_t) 
                         ((mach_no_senders_notification_t *) 
                         request_header)->not_count);
                      (ipc_port_t)reply_header->msgh_remote_port
                          = MACH_PORT_NULL;
                      return TRUE;
                   }
                   break;
                case MACH_NOTIFY_PORT_DELETED:
                case MACH_NOTIFY_PORT_DESTROYED:
                case MACH_NOTIFY_SEND_ONCE:
                case MACH_NOTIFY_DEAD_NAME:
                break;

                default:
                return FALSE;
        }
        switch (ip_kotype(port)) {

#ifdef IOKIT
                case IKOT_IOKIT_OBJECT:
                case IKOT_IOKIT_CONNECT:
                case IKOT_IOKIT_SPARE:
                {
                extern boolean_t iokit_notify( mach_msg_header_t *msg);

                return iokit_notify(request_header);
                }
#endif
                default:
                return FALSE;
        }
}



#include <mach_kdb.h>
#if     MACH_COUNTERS && MACH_KDB

#include <ddb/db_output.h>
#include <ddb/db_sym.h>

#define printf  kdbprintf

extern void kobjserver_stats(void);
extern void bucket_stats_print(mig_hash_t *bucket);

extern void kobjserver_stats_clear(void);


void
kobjserver_stats_clear(void)
{
        int i;
        for (i = 0; i < MAX_MIG_ENTRIES; i++) {
                mig_buckets[i].callcount = 0;
        }
}

void
kobjserver_stats(void)
{
    register unsigned int i, n = sizeof(mig_e)/sizeof(rpc_subsystem_t);
    register unsigned int howmany;
    register mach_msg_id_t j, pos, nentry, range;
        
    db_printf("Kobject server call counts:\n");
    for (i = 0; i < n; i++) {
        db_printf("  ");
        db_printsym((vm_offset_t)mig_e[i], DB_STGY_ANY);
        db_printf(":\n");
        range = mig_e[i]->end - mig_e[i]->start;
        if (!mig_e[i]->start || range < 0) continue;

        for  (j = 0; j < range; j++) {
            nentry = j + mig_e[i]->start;       
            for (pos = MIG_HASH(nentry) % MAX_MIG_ENTRIES, howmany = 1;
                 mig_buckets[pos].num;
                 pos = ++pos % MAX_MIG_ENTRIES, howmany++) {
                    if (mig_buckets[pos].num == nentry)
                        bucket_stats_print(&mig_buckets[pos]);
            }
        }
    }
}

void
bucket_stats_print(mig_hash_t *bucket)
{
        if (bucket->callcount) {
                db_printf("    ");
                db_printsym((vm_offset_t)bucket->routine, DB_STGY_ANY);
                db_printf(" (%d):\t%d\n", bucket->num, bucket->callcount);
        }
}


#endif  /* MACH_COUNTERS && MACH_KDB */