1*0a6a1f1dSLionel Sambuc/* $NetBSD: __vfork14.S,v 1.6 2014/03/06 19:02:58 skrll Exp $ */ 22fe8fb19SBen Gras 32fe8fb19SBen Gras/*- 42fe8fb19SBen Gras * Copyright (c) 2001 The NetBSD Foundation, Inc. 52fe8fb19SBen Gras * All rights reserved. 62fe8fb19SBen Gras * 72fe8fb19SBen Gras * This code is derived from software contributed to The NetBSD Foundation 82fe8fb19SBen Gras * by Matt Fredette. 92fe8fb19SBen Gras * 102fe8fb19SBen Gras * Redistribution and use in source and binary forms, with or without 112fe8fb19SBen Gras * modification, are permitted provided that the following conditions 122fe8fb19SBen Gras * are met: 132fe8fb19SBen Gras * 1. Redistributions of source code must retain the above copyright 142fe8fb19SBen Gras * notice, this list of conditions and the following disclaimer. 152fe8fb19SBen Gras * 2. Redistributions in binary form must reproduce the above copyright 162fe8fb19SBen Gras * notice, this list of conditions and the following disclaimer in the 172fe8fb19SBen Gras * documentation and/or other materials provided with the distribution. 182fe8fb19SBen Gras * 192fe8fb19SBen Gras * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 202fe8fb19SBen Gras * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 212fe8fb19SBen Gras * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 222fe8fb19SBen Gras * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 232fe8fb19SBen Gras * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 242fe8fb19SBen Gras * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 252fe8fb19SBen Gras * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 262fe8fb19SBen Gras * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 272fe8fb19SBen Gras * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 282fe8fb19SBen Gras * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 292fe8fb19SBen Gras * POSSIBILITY OF SUCH DAMAGE. 302fe8fb19SBen Gras */ 312fe8fb19SBen Gras 322fe8fb19SBen Gras#include <sys/errno.h> 332fe8fb19SBen Gras#include "SYS.h" 342fe8fb19SBen Gras 352fe8fb19SBen GrasENTRY(__vfork14, 0) 362fe8fb19SBen Gras /* 372fe8fb19SBen Gras * NB: __vfork14 is a tricky syscall. We can't save 382fe8fb19SBen Gras * any values on the stack, because the stack will be 392fe8fb19SBen Gras * trashed by the child, leaving garbage for when the 402fe8fb19SBen Gras * parent returns. 412fe8fb19SBen Gras * 422fe8fb19SBen Gras * So we must save values in registers, specifically, 432fe8fb19SBen Gras * registers that the kernel is willing to preserve 442fe8fb19SBen Gras * across the syscall. Normally, this would be callee- 452fe8fb19SBen Gras * saved registers, with the kernel being the callee, 462fe8fb19SBen Gras * but the problem is that we, too, are a callee, and 472fe8fb19SBen Gras * would have to save that very same register somewhere, 482fe8fb19SBen Gras * because *our* caller is counting on us to do so. 492fe8fb19SBen Gras * 502fe8fb19SBen Gras * What we need is a normally caller-saved register, 512fe8fb19SBen Gras * that the kernel is willing to save for us. The 522fe8fb19SBen Gras * syscall entry code in locore.S has been modified 532fe8fb19SBen Gras * to do just this for the t4 register. 542fe8fb19SBen Gras */ 552fe8fb19SBen Gras .import __cerror, code 562fe8fb19SBen Gras 572fe8fb19SBen Gras copy %rp, %t4 582fe8fb19SBen Gras ldil L%SYSCALLGATE, %r1 59*0a6a1f1dSLionel Sambuc ble 4(%sr2, %r1) 602fe8fb19SBen Gras ldi SYS___vfork14, %t1 612fe8fb19SBen Gras comb,<> %r0, %t1, __cerror 622fe8fb19SBen Gras copy %t4, %rp 632fe8fb19SBen Gras addi -1, %ret1, %ret1 642fe8fb19SBen Gras bv %r0(%rp) 652fe8fb19SBen Gras and %ret0, %ret1, %ret0 662fe8fb19SBen GrasEXIT(__vfork14) 67