1 1.4 christos /* $NetBSD: makecontext.c,v 1.4 2012/03/21 14:03:06 christos Exp $ */ 2 1.2 thorpej 3 1.2 thorpej /*- 4 1.2 thorpej * Copyright (c) 2001 The NetBSD Foundation, Inc. 5 1.2 thorpej * All rights reserved. 6 1.2 thorpej * 7 1.2 thorpej * This code is derived from software contributed to The NetBSD Foundation 8 1.2 thorpej * by Klaus Klein. 9 1.2 thorpej * 10 1.2 thorpej * Redistribution and use in source and binary forms, with or without 11 1.2 thorpej * modification, are permitted provided that the following conditions 12 1.2 thorpej * are met: 13 1.2 thorpej * 1. Redistributions of source code must retain the above copyright 14 1.2 thorpej * notice, this list of conditions and the following disclaimer. 15 1.2 thorpej * 2. Redistributions in binary form must reproduce the above copyright 16 1.2 thorpej * notice, this list of conditions and the following disclaimer in the 17 1.2 thorpej * documentation and/or other materials provided with the distribution. 18 1.2 thorpej * 19 1.2 thorpej * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 1.2 thorpej * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 1.2 thorpej * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 1.2 thorpej * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 1.2 thorpej * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 1.2 thorpej * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 1.2 thorpej * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 1.2 thorpej * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 1.2 thorpej * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 1.2 thorpej * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 1.2 thorpej * POSSIBILITY OF SUCH DAMAGE. 30 1.2 thorpej */ 31 1.2 thorpej 32 1.2 thorpej #include <sys/cdefs.h> 33 1.2 thorpej #if defined(LIBC_SCCS) && !defined(lint) 34 1.4 christos __RCSID("$NetBSD: makecontext.c,v 1.4 2012/03/21 14:03:06 christos Exp $"); 35 1.2 thorpej #endif 36 1.2 thorpej 37 1.2 thorpej #include <stddef.h> 38 1.2 thorpej #include <inttypes.h> 39 1.2 thorpej #include <ucontext.h> 40 1.2 thorpej #include "extern.h" 41 1.2 thorpej 42 1.2 thorpej #include <stdarg.h> 43 1.2 thorpej 44 1.2 thorpej void 45 1.2 thorpej makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...) 46 1.2 thorpej { 47 1.2 thorpej __greg_t *gr = ucp->uc_mcontext.__gregs; 48 1.2 thorpej int i; 49 1.2 thorpej unsigned int *sp; 50 1.2 thorpej va_list ap; 51 1.2 thorpej 52 1.2 thorpej /* Compute and align stack pointer. */ 53 1.2 thorpej sp = (unsigned int *) 54 1.2 thorpej (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & ~7); 55 1.2 thorpej /* Allocate necessary stack space for arguments exceeding r0-3. */ 56 1.2 thorpej if (argc > 4) 57 1.2 thorpej sp -= argc - 4; 58 1.4 christos gr[_REG_SP] = (__greg_t)(uintptr_t)sp; 59 1.2 thorpej /* Wipe out frame pointer. */ 60 1.2 thorpej gr[_REG_FP] = 0; 61 1.2 thorpej /* Arrange for return via the trampoline code. */ 62 1.4 christos gr[_REG_LR] = (__greg_t)(uintptr_t)_resumecontext; 63 1.4 christos gr[_REG_PC] = (__greg_t)(uintptr_t)func; 64 1.2 thorpej 65 1.2 thorpej va_start(ap, argc); 66 1.2 thorpej /* Pass up to four arguments in r0-3. */ 67 1.2 thorpej for (i = 0; i < argc && i < 4; i++) 68 1.2 thorpej gr[_REG_R0 + i] = va_arg(ap, int); 69 1.2 thorpej /* Pass any additional arguments on the stack. */ 70 1.2 thorpej for (argc -= i; argc > 0; argc--) 71 1.2 thorpej *sp++ = va_arg(ap, int); 72 1.2 thorpej va_end(ap); 73 1.2 thorpej } 74
Indexes created Sun Sep 21 20:09:37 GMT 2025