1 /* $NetBSD: makecontext.c,v 1.2 2003/01/18 11:08:11 thorpej 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 * 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 <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 __RCSID("$NetBSD: makecontext.c,v 1.2 2003/01/18 11:08:11 thorpej Exp $"); 42 #endif 43 44 #include <inttypes.h> 45 #include <stddef.h> 46 #include <ucontext.h> 47 #include "extern.h" 48 49 #if __STDC__ 50 #include <stdarg.h> 51 #else 52 #include <varargs.h> 53 #endif 54 55 56 void 57 #if __STDC__ 58 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...) 59 #else 60 makecontext(ucp, func, argc, va_alist) 61 ucontext_t *ucp; 62 void (*func)(); 63 int argc; 64 va_dcl 65 #endif 66 { 67 __greg_t *gr = ucp->uc_mcontext.__gregs; 68 unsigned int *sp; 69 va_list ap; 70 71 /* LINTED __greg_t is safe */ 72 gr[_REG_EIP] = (__greg_t)func; 73 74 /* LINTED uintptr_t is safe */ 75 sp = (int *)((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size); 76 /* LINTED uintptr_t is safe */ 77 sp = (int *)((uintptr_t)sp & ~0x3); /* Align on word boundary. */ 78 sp -= argc + 1; /* Make room for ret and args. */ 79 /* LINTED __greg_t is safe */ 80 gr[_REG_UESP] = (__greg_t)sp; 81 gr[_REG_EBP] = (__greg_t)0; /* Wipe out frame pointer. */ 82 83 /* Put return address on top of stack. */ 84 /* LINTED uintptr_t is safe */ 85 *sp++ = (uintptr_t)_resumecontext; 86 87 /* Construct argument list. */ 88 #if __STDC__ 89 va_start(ap, argc); 90 #else 91 va_start(ap); 92 #endif 93 while (argc-- > 0) { 94 /* LINTED uintptr_t is safe */ 95 *sp++ = va_arg(ap, uintptr_t); 96 } 97 va_end(ap); 98 } 99