1/* $NetBSD: resumecontext.S,v 1.6 2014/05/22 15:01:56 uebayasi 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 * Modified for x86-64 by fvdl@wasabisystems.com 32 */ 33 34#include <machine/asm.h> 35#include "SYS.h" 36 37#if defined(LIBC_SCCS) && !defined(lint) 38 RCSID("$NetBSD: resumecontext.S,v 1.6 2014/05/22 15:01:56 uebayasi Exp $") 39#endif /* LIBC_SCCS && !lint */ 40 41/* 42 * This assembly-language implementation differs from the (obvious) 43 * C-language implementation only in not clobbering the previous 44 * function's return address (us), which is the point of the exercise. 45 */ 46 47NENTRY(_resumecontext) /* profiling prologue would clobber TOS */ 48 leaq -(8 + 784)(%rsp),%rdi /* retaddr + sizeof (ucontext_t) */ 49 andq $~15,%rdi /* align on _UC_UCONTEXT_ALIGN */ 50 movq %rdi,%rsp 51#ifdef __PIC__ 52 call PIC_PLT(_C_LABEL(_getcontext)) 53#else 54 call _C_LABEL(_getcontext) 55#endif 56 movq 8(%rsp),%rdi /* uc_link */ 57 testq %rdi,%rdi /* link end? */ 58 jnz 9f 59 60 /* normal exit */ 61#ifdef __PIC__ 62 call PIC_PLT(_C_LABEL(exit)) 63#else 64 call _C_LABEL(exit) 65#endif 66 679: 68#ifdef __PIC__ 69 call PIC_PLT(_C_LABEL(setcontext)) 70#else 71 call _C_LABEL(setcontext) 72#endif 73 /* NOTREACHED */ 74 75 /* something is wrong, pull the brake */ 76 movq $-1,%rdi 77 movq $SYS_exit,%rax 78 syscall 79 /* NOTREACHED */ 80END(_resumecontext) 81