1 /* $NetBSD: makecontext.c,v 1.3 2003/01/19 08:53:36 matt 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 2003/01/19 08:53:36 matt Exp $"); 42 #endif 43 44 #include <inttypes.h> 45 #include <stddef.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 uintptr_t *sp; 56 int i; 57 va_list ap; 58 59 void __resumecontext(void); 60 61 /* LINTED uintptr_t is safe */ 62 sp = (uintptr_t *) 63 ((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size); 64 /* LINTED uintptr_t is safe */ 65 sp -= (argc >= 4 ? argc : 4); /* Make room for >=4 arguments. */ 66 sp = (uintptr_t *) 67 ((uintptr_t)sp & ~0x7); /* Align on double-word boundary. */ 68 69 gr[_REG_SP] = (__greg_t)sp; 70 gr[_REG_RA] = (__greg_t)__resumecontext; 71 gr[_REG_T9] = (__greg_t)func; /* required for .abicalls */ 72 gr[_REG_EPC] = (__greg_t)func; 73 74 /* Construct argument list. */ 75 va_start(ap, argc); 76 /* Up to the first four arguments are passed in $a0-3. */ 77 for (i = 0; i < argc && i < 4; i++) 78 /* LINTED uintptr_t is safe */ 79 gr[_REG_A0 + i] = va_arg(ap, uintptr_t); 80 /* Pass remaining arguments on the stack above the $a0-3 gap. */ 81 for (sp += 4; i < argc; i++) 82 /* LINTED uintptr_t is safe */ 83 *sp++ = va_arg(ap, uintptr_t); 84 va_end(ap); 85 } 86