1 /* $NetBSD: makecontext.c,v 1.2 2003/01/18 11:06:24 thorpej Exp $ */
4 * Copyright (c) 2001 The NetBSD Foundation, Inc.
7 * This code is derived from software contributed to The NetBSD Foundation
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
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.
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.
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
49 extern void _ctx_start(void);
52 ctx_done(ucontext_t *ucp)
55 if (ucp->uc_link == NULL)
58 setcontext((const ucontext_t *)ucp->uc_link);
63 __weak_reference(__makecontext, makecontext);
66 __makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
68 __greg_t *gr = ucp->uc_mcontext.__gregs;
73 /* Compute and align stack pointer. */
75 (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size -
76 sizeof(double)) & ~7);
77 /* Allocate necessary stack space for arguments exceeding r0-3. */
80 gr[_REG_SP] = (__greg_t)sp;
81 /* Wipe out frame pointer. */
83 /* Arrange for return via the trampoline code. */
84 gr[_REG_PC] = (__greg_t)_ctx_start;
85 gr[_REG_R4] = (__greg_t)func;
86 gr[_REG_R5] = (__greg_t)ucp;
89 /* Pass up to four arguments in r0-3. */
90 for (i = 0; i < argc && i < 4; i++)
91 gr[_REG_R0 + i] = va_arg(ap, int);
92 /* Pass any additional arguments on the stack. */
93 for (argc -= i; argc > 0; argc--)
94 *sp++ = va_arg(ap, int);