1 /* $NetBSD: makecontext.c,v 1.2 2003/01/18 11:06:24 thorpej Exp $ */
4 * SPDX-License-Identifier: BSD-2-Clause-NetBSD
6 * Copyright (c) 2001 The NetBSD Foundation, Inc.
9 * This code is derived from software contributed to The NetBSD Foundation
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
21 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
23 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31 * POSSIBILITY OF SUCH DAMAGE.
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
44 extern void _ctx_start(void);
47 ctx_done(ucontext_t *ucp)
50 if (ucp->uc_link == NULL)
53 setcontext((const ucontext_t *)ucp->uc_link);
58 __weak_reference(__makecontext, makecontext);
61 __makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
63 __greg_t *gr = ucp->uc_mcontext.__gregs;
68 /* Compute and align stack pointer. */
70 (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size -
71 sizeof(double)) & ~7);
72 /* Allocate necessary stack space for arguments exceeding r0-3. */
75 gr[_REG_SP] = (__greg_t)sp;
76 /* Wipe out frame pointer. */
78 /* Arrange for return via the trampoline code. */
79 gr[_REG_PC] = (__greg_t)_ctx_start;
80 gr[_REG_R4] = (__greg_t)func;
81 gr[_REG_R5] = (__greg_t)ucp;
84 /* Pass up to four arguments in r0-3. */
85 for (i = 0; i < argc && i < 4; i++)
86 gr[_REG_R0 + i] = va_arg(ap, int);
87 /* Pass any additional arguments on the stack. */
88 for (argc -= i; argc > 0; argc--)
89 *sp++ = va_arg(ap, int);