1/* $OpenBSD: _setjmp.S,v 1.6 2016/05/30 02:11:21 guenther Exp $ */ 2/*- 3 * Copyright (c) 1990 The Regents of the University of California. 4 * All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * William Jolitz. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34#include <machine/asm.h> 35 36 .global __jmpxor 37 38/* 39 * C library -- _setjmp, _longjmp 40 * 41 * _longjmp(a,v) 42 * will generate a "return(v)" from the last call to 43 * _setjmp(a) 44 * by restoring registers from the stack. 45 * The previous signal state is NOT restored. 46 */ 47 48ENTRY(_setjmp) 49 call 1f 501: popl %ecx 51 addl $__jmpxor-1b,%ecx # load cookie address 52 movl 4(%esp),%eax 53 movl 0(%esp),%edx 54 xorl 0(%ecx),%edx # use eip cookie 55 movl %edx, 0(%eax) 56 movl %ebx, 4(%eax) 57 movl %esp, %edx 58 xorl 4(%ecx),%edx # use esp cookie 59 movl %edx, 8(%eax) 60 movl 8(%ecx),%ecx # load ebp cookie over cookie address 61 xorl %ebp, %ecx 62 movl %ecx,12(%eax) 63 movl %esi,16(%eax) 64 movl %edi,20(%eax) 65 xorl %eax,%eax 66 ret 67END(_setjmp) 68 69ENTRY(_longjmp) 70 call 1f 711: popl %ecx 72 addl $__jmpxor-1b,%ecx # load cookie address 73 movl 4(%esp),%edx 74 movl 8(%esp),%eax 75 movl 4(%edx),%ebx 76 movl 8(%edx),%esi # load xor'ed esp into safe register 77 xorl 4(%ecx),%esi # use esp cookie 78 movl %esi, %esp # un-xor'ed esp is safe to use 79 movl 12(%edx),%ebp 80 xorl 8(%ecx),%ebp # use ebp cookie 81 movl 16(%edx),%esi 82 movl 20(%edx),%edi 83 movl 0(%ecx),%ecx # load eip cookie over cookie address 84 xorl 0(%edx),%ecx # overwrite eip cookie 85 testl %eax,%eax 86 jnz 1f 87 incl %eax 881: movl %ecx,0(%esp) 89 ret 90END(_longjmp) 91