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      1 /*	$NetBSD: db_syncobj.c,v 1.3 2023/10/15 10:27:25 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2023 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #define	__MUTEX_PRIVATE
     30 #define	__RWLOCK_PRIVATE
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: db_syncobj.c,v 1.3 2023/10/15 10:27:25 riastradh Exp $");
     34 
     35 #include <sys/types.h>
     36 
     37 #include <sys/mutex.h>
     38 #include <sys/null.h>
     39 #include <sys/rwlock.h>
     40 #include <sys/syncobj.h>
     41 
     42 #include <ddb/ddb.h>
     43 
     44 struct lwp *
     45 db_syncobj_owner(const struct syncobj *sobj, wchan_t wchan)
     46 {
     47 	db_expr_t mutex_syncobj_;
     48 	db_expr_t rw_syncobj_;
     49 
     50 	if (db_value_of_name("mutex_syncobj", &mutex_syncobj_) &&
     51 	    (db_expr_t)(uintptr_t)sobj == mutex_syncobj_) {
     52 		volatile const struct kmutex *mtx = wchan;
     53 		uintptr_t owner;
     54 
     55 		db_read_bytes((db_addr_t)&mtx->mtx_owner, sizeof(owner),
     56 		    (char *)&owner);
     57 		return (struct lwp *)(owner & MUTEX_THREAD);
     58 
     59 	} else if (db_value_of_name("rw_syncobj", &rw_syncobj_) &&
     60 	    (db_expr_t)(uintptr_t)sobj == rw_syncobj_) {
     61 		volatile const struct krwlock *rw = wchan;
     62 		uintptr_t owner;
     63 
     64 		db_read_bytes((db_addr_t)&rw->rw_owner, sizeof(owner),
     65 		    (char *)&owner);
     66 		if (owner & RW_WRITE_LOCKED)
     67 			return (struct lwp *)(owner & RW_THREAD);
     68 		return NULL;
     69 
     70 	} else {
     71 		return NULL;
     72 	}
     73 }
     74