1 /* $NetBSD: makecontext.c,v 1.5 2009/12/14 01:07:42 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 * 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 1.5 2009/12/14 01:07:42 matt Exp $"); 35 #endif 36 37 #include <inttypes.h> 38 #include <stddef.h> 39 #include <ucontext.h> 40 #include "extern.h" 41 42 #include <stdarg.h> 43 44 void 45 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...) 46 { 47 __greg_t *gr = ucp->uc_mcontext.__gregs; 48 __greg_t *sp; 49 int i; 50 va_list ap; 51 52 void __resumecontext(void); 53 54 /* LINTED uintptr_t is safe */ 55 sp = (__greg_t *) 56 ((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size); 57 /* LINTED uintptr_t is safe */ 58 #if defined(__mips_o32) || defined(__mips_o64) 59 sp -= (argc >= 4 ? argc : 4); /* Make room for >=4 arguments. */ 60 sp = (__greg_t *) 61 ((uintptr_t)sp & ~0x7); /* Align on double-word boundary. */ 62 #elif defined(__mips_n32) || defined(__mips_n64) 63 sp -= (argc > 8 ? argc - 8 : 0); /* Make room for > 8 arguments. */ 64 sp = (__greg_t *) 65 ((uintptr_t)sp & ~0xf); /* Align on quad-word boundary. */ 66 #endif 67 68 gr[_REG_SP] = (intptr_t)sp; 69 gr[_REG_RA] = (intptr_t)__resumecontext; 70 gr[_REG_T9] = (intptr_t)func; /* required for .abicalls */ 71 gr[_REG_EPC] = (intptr_t)func; 72 73 /* Construct argument list. */ 74 va_start(ap, argc); 75 #if defined(__mips_o32) || defined(__mips_o64) 76 /* Up to the first four arguments are passed in $a0-3. */ 77 for (i = 0; i < argc && i < 4; i++) 78 /* LINTED __greg_t is safe */ 79 gr[_REG_A0 + i] = va_arg(ap, __greg_t); 80 /* Pass remaining arguments on the stack above the $a0-3 gap. */ 81 sp += i; 82 #endif 83 #if defined(__mips_n32) || defined(__mips_n64) 84 /* Up to the first 8 arguments are passed in $a0-7. */ 85 for (i = 0; i < argc && i < 8; i++) 86 /* LINTED __greg_t is safe */ 87 gr[_REG_A0 + i] = va_arg(ap, __greg_t); 88 /* Pass remaining arguments on the stack above the $a0-3 gap. */ 89 #endif 90 /* Pass remaining arguments on the stack above the $a0-3 gap. */ 91 for (; i < argc; i++) 92 /* LINTED uintptr_t is safe */ 93 *sp++ = va_arg(ap, __greg_t); 94 va_end(ap); 95 } 96