1 /* $NetBSD: makecontext.c,v 1.1 2003/01/19 19:07:30 matt Exp $ */ 2 3 /*- 4 * Copyright (c) 2003 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Matt Thomas. 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 1.1 2003/01/19 19:07:30 matt Exp $"); 42 #endif 43 44 #include <stddef.h> 45 #include <inttypes.h> 46 #include <ucontext.h> 47 #include "extern.h" 48 49 #include <stdarg.h> 50 51 void 52 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...) 53 { 54 __greg_t *gr = ucp->uc_mcontext.__gregs; 55 va_list ap; 56 int *sp; 57 int i; 58 59 /* Compute and align stack pointer. */ 60 sp = (int *) 61 (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & ~0x3); 62 63 /* 64 * Allocate necessary stack space for arguments including arg count 65 * and call frame 66 */ 67 sp -= argc + 1 + 5; 68 69 va_start(ap, argc); 70 sp[5] = argc; 71 for (i = 0; argc > 0; argc--, i++) 72 sp[5 + i] = va_arg(ap, int); 73 va_end(ap); 74 75 sp[0] = 0; /* condition handler is null */ 76 sp[1] = 0x20000000; /* make this a CALLS frame */ 77 sp[2] = 0; /* saved argument pointer */ 78 sp[3] = 0; /* saved frame pointer */ 79 sp[4] = (int)_resumecontext; /* return via trampoline code */ 80 81 gr[_REG_AP] = (__greg_t)(sp + 5); 82 gr[_REG_SP] = (__greg_t)sp; 83 gr[_REG_FP] = (__greg_t)sp; 84 gr[_REG_PC] = (__greg_t)func+2; 85 86 } 87