1/* $NetBSD: resumecontext.S,v 1.4 2006/12/13 10:48:02 martin Exp $ */ 2 3/*- 4 * Copyright (c) 2001 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Klaus Klein. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39#include <machine/asm.h> 40 41#if defined(LIBC_SCCS) && !defined(lint) 42 RCSID("$NetBSD: resumecontext.S,v 1.4 2006/12/13 10:48:02 martin Exp $") 43#endif /* LIBC_SCCS && !lint */ 44 45/* 46 * This assembly-language implementation differs from the (obvious) 47 * C-language implementation only in not clobbering the previous 48 * function's return address (us), which is the point of the exercise. 49 */ 50 51ENTRY(_resumecontext) 52 subl #(4 + 1024),%sp /* retaddr preservation + ucontext_t */ 53 lea %sp@,%a0 54 movl %a0,%sp@- 55 jbsr PIC_PLT(_C_LABEL(_getcontext)) 56 movl %sp@(4 + 4),%sp@ /* uc_link */ 57 tstl %sp@ /* check for NULL */ 58 jne 1f 59 jbsr PIC_PLT(_C_LABEL(exit)) /* cleanly exit(0) */ 60 jmp 2f 611: jbsr PIC_PLT(_C_LABEL(setcontext)) 62 /* NOTREACHED */ 63 /* But just in case... */ 642: movl #-1,%sp@ 65 jbsr PIC_PLT(_C_LABEL(_exit)) 66 /* NOTREACHED */ 67