1 /* $NetBSD: makecontext.c,v 1.4 2008/04/28 20:22:56 martin 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 <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 __RCSID("$NetBSD: makecontext.c,v 1.4 2008/04/28 20:22:56 martin Exp $"); 35 #endif 36 37 #include <inttypes.h> 38 #include <stddef.h> 39 #include <ucontext.h> 40 #include "extern.h" 41 42 #if __STDC__ 43 #include <stdarg.h> 44 #else 45 #include <varargs.h> 46 #endif 47 48 49 void 50 #if __STDC__ 51 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...) 52 #else 53 makecontext(ucp, func, argc, va_alist) 54 ucontext_t *ucp; 55 void (*func)(); 56 int argc; 57 va_dcl 58 #endif 59 { 60 __greg_t *gr = ucp->uc_mcontext.__gregs; 61 unsigned int *sp; 62 va_list ap; 63 64 /* LINTED __greg_t is safe */ 65 gr[_REG_EIP] = (__greg_t)func; 66 67 /* LINTED uintptr_t is safe */ 68 sp = (unsigned int *)((uintptr_t)ucp->uc_stack.ss_sp + 69 ucp->uc_stack.ss_size); 70 /* Align on word boundary. */ 71 /* LINTED uintptr_t is safe */ 72 sp = (unsigned int *)((uintptr_t)sp & ~0x3); 73 sp -= argc + 1; /* Make room for ret and args. */ 74 /* LINTED __greg_t is safe */ 75 gr[_REG_UESP] = (__greg_t)sp; 76 gr[_REG_EBP] = (__greg_t)0; /* Wipe out frame pointer. */ 77 78 /* Put return address on top of stack. */ 79 /* LINTED uintptr_t is safe */ 80 *sp++ = (uintptr_t)_resumecontext; 81 82 /* Construct argument list. */ 83 #if __STDC__ 84 va_start(ap, argc); 85 #else 86 va_start(ap); 87 #endif 88 while (argc-- > 0) { 89 /* LINTED uintptr_t is safe */ 90 *sp++ = va_arg(ap, uintptr_t); 91 } 92 va_end(ap); 93 } 94