1/* $NetBSD: resumecontext.S,v 1.7 2013/09/12 15:36:15 joerg Exp $ */ 2 3/*- 4 * Copyright (c) 1999 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 "SYS.h" 34 35#if defined(LIBC_SCCS) && !defined(lint) 36 RCSID("$NetBSD: resumecontext.S,v 1.7 2013/09/12 15:36:15 joerg 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 45NENTRY(_resumecontext) /* profiling prologue would clobber TOS */ 46 leal -(4 + 776)(%esp),%ecx /* retaddr + sizeof (ucontext_t) */ 47 andl $~(0xf),%ecx /* align on _UC_UCONTEXT_ALIGN */ 48 movl %ecx,%esp 49 PIC_PROLOGUE 50 pushl %ecx 51#ifdef __PIC__ 52 call PIC_PLT(_C_LABEL(_getcontext)) 53#else 54 call _C_LABEL(_getcontext) 55#endif 56 addl $4,%esp 57 PIC_EPILOGUE 58 movl 4(%esp),%ecx /* uc_link */ 59 PIC_PROLOGUE 60 pushl %ecx /* argument for exit() or setcontext() */ 61 testl %ecx,%ecx /* link end? */ 62 jnz 9f /* watch out for local label use in PIC_* */ 63 64 /* normal exit */ 65#ifdef __PIC__ 66 call PIC_PLT(_C_LABEL(exit)) 67#else 68 call _C_LABEL(exit) 69#endif 70 /* NOTREACHED */ 71 729: 73#ifdef __PIC__ 74 call PIC_PLT(_C_LABEL(setcontext)) 75#else 76 call _C_LABEL(setcontext) 77#endif 78 /* NOTREACHED */ 79 80 /* something is wrong, pull the brake */ 81 pushl $-1 82 pushl %eax /* unused return address */ 83 SYSTRAP(exit) 84