11.4Schristos/* $NetBSD: makecontext.c,v 1.4 2012/03/22 17:32:22 christos Exp $ */ 21.1Smatt 31.1Smatt/*- 41.1Smatt * Copyright (c) 2003 The NetBSD Foundation, Inc. 51.1Smatt * All rights reserved. 61.1Smatt * 71.1Smatt * This code is derived from software contributed to The NetBSD Foundation 81.1Smatt * by Matt Thomas. 91.1Smatt * 101.1Smatt * Redistribution and use in source and binary forms, with or without 111.1Smatt * modification, are permitted provided that the following conditions 121.1Smatt * are met: 131.1Smatt * 1. Redistributions of source code must retain the above copyright 141.1Smatt * notice, this list of conditions and the following disclaimer. 151.1Smatt * 2. Redistributions in binary form must reproduce the above copyright 161.1Smatt * notice, this list of conditions and the following disclaimer in the 171.1Smatt * documentation and/or other materials provided with the distribution. 181.1Smatt * 191.1Smatt * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 201.1Smatt * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 211.1Smatt * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 221.1Smatt * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 231.1Smatt * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 241.1Smatt * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 251.1Smatt * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 261.1Smatt * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 271.1Smatt * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 281.1Smatt * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 291.1Smatt * POSSIBILITY OF SUCH DAMAGE. 301.1Smatt */ 311.1Smatt 321.1Smatt#include <sys/cdefs.h> 331.1Smatt#if defined(LIBC_SCCS) && !defined(lint) 341.4Schristos__RCSID("$NetBSD: makecontext.c,v 1.4 2012/03/22 17:32:22 christos Exp $"); 351.1Smatt#endif 361.1Smatt 371.1Smatt#include <stddef.h> 381.1Smatt#include <inttypes.h> 391.1Smatt#include <ucontext.h> 401.1Smatt#include "extern.h" 411.1Smatt 421.1Smatt#include <stdarg.h> 431.1Smatt 441.1Smattvoid 451.1Smattmakecontext(ucontext_t *ucp, void (*func)(void), int argc, ...) 461.1Smatt{ 471.1Smatt __greg_t *gr = ucp->uc_mcontext.__gregs; 481.1Smatt va_list ap; 491.1Smatt int *sp; 501.1Smatt int i; 511.1Smatt 521.1Smatt /* Compute and align stack pointer. */ 531.1Smatt sp = (int *) 541.1Smatt (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & ~0x3); 551.1Smatt 561.1Smatt /* 571.1Smatt * Allocate necessary stack space for arguments including arg count 581.1Smatt * and call frame 591.1Smatt */ 601.1Smatt sp -= argc + 1 + 5; 611.1Smatt 621.1Smatt va_start(ap, argc); 631.1Smatt sp[5] = argc; 641.2Smatt for (i = 1; argc > 0; argc--, i++) 651.1Smatt sp[5 + i] = va_arg(ap, int); 661.1Smatt va_end(ap); 671.1Smatt 681.1Smatt sp[0] = 0; /* condition handler is null */ 691.1Smatt sp[1] = 0x20000000; /* make this a CALLS frame */ 701.1Smatt sp[2] = 0; /* saved argument pointer */ 711.1Smatt sp[3] = 0; /* saved frame pointer */ 721.4Schristos sp[4] = (int)(uintptr_t)_resumecontext+2;/* return via trampoline code */ 731.1Smatt 741.4Schristos gr[_REG_AP] = (__greg_t)(uintptr_t)(sp + 5); 751.4Schristos gr[_REG_SP] = (__greg_t)(uintptr_t)sp; 761.4Schristos gr[_REG_FP] = (__greg_t)(uintptr_t)sp; 771.4Schristos gr[_REG_PC] = (__greg_t)(uintptr_t)func+2; 781.1Smatt 791.1Smatt} 80