1 /* $NetBSD: makecontext.c,v 1.3 2004/03/01 19:26:29 drochner Exp $ */ 2 3 /*- 4 * Copyright (c) 2001 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 1.3 2004/03/01 19:26:29 drochner 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 int i; 56 unsigned long *sp; 57 va_list ap; 58 59 void __resumecontext(void); 60 61 /* Compute and align stack pointer. */ 62 sp = (unsigned long *) 63 (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & ~0x7); 64 /* Allocate necessary stack space for arguments exceeding a0-5. */ 65 if (argc > 6) 66 sp -= (argc - 6); 67 gr[_REG_SP] = (__greg_t)sp; 68 /* Arrange for return via the trampoline code. */ 69 gr[_REG_RA] = (__greg_t)__resumecontext; 70 gr[_REG_PC] = (__greg_t)func; 71 gr[_REG_PV] = (__greg_t)func; 72 73 va_start(ap, argc); 74 /* Pass up to six arguments in a0-5. */ 75 for (i = 0; i < argc && i < 6; i++) 76 gr[_REG_A0 + i] = va_arg(ap, unsigned long); 77 /* Pass any additional arguments on the stack. */ 78 for (argc -= i; argc > 0; argc--) 79 *sp++ = va_arg(ap, unsigned long); 80 va_end(ap); 81 } 82