1/* $NetBSD: resumecontext.S,v 1.7 2013/07/16 22:12:20 matt 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 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32#include <machine/asm.h> 33#include "assym.h" 34 35#if defined(LIBC_SCCS) && !defined(lint) 36 RCSID("$NetBSD: resumecontext.S,v 1.7 2013/07/16 22:12:20 matt Exp $") 37#endif /* LIBC_SCCS && !lint */ 38 39/* 40 * This assembly-language implementation differs from the (obvious) 41 * C-language implementation only in not clobbering the previous 42 * function's return address (us), which is the point of the exercise. 43 */ 44 45ENTRY(_resumecontext) 46 subl #(4 + UC_SIZE),%sp /* retaddr preservation + ucontext_t */ 47 lea (%sp),%a0 48 movl %a0,-(%sp) 49 jbsr PIC_PLT(_C_LABEL(_getcontext)) 50 movl (4 + UC_LINK)(%sp),(%sp) /* uc_link */ 51 tstl (%sp) /* check for NULL */ 52 jne 1f 53 jbsr PIC_PLT(_C_LABEL(exit)) /* cleanly exit(0) */ 54 jmp 2f 551: jbsr PIC_PLT(_C_LABEL(setcontext)) 56 /* NOTREACHED */ 57 /* But just in case... */ 582: movl #-1,(%sp) 59 jbsr PIC_PLT(_C_LABEL(_exit)) 60 /* NOTREACHED */ 61END(_resumecontext) 62