This is xnu-8019. See this file in:
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2017 Apple, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
#ifndef _SYS_SYSTRACE_ARGS_H
#define _SYS_SYSTRACE_ARGS_H

#include <sys/syscall.h>
#include <sys/sysproto.h>

void systrace_args(int sysnum, void *params, uint64_t *uarg);
void systrace_entry_setargdesc(int sysnum, int ndx, char *desc, size_t descsz);
void systrace_return_setargdesc(int sysnum, int ndx, char *desc, size_t descsz);

#endif /* _SYS_SYSTRACE_ARGS_H */