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.
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.
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
42 extern void _ctx_start(void);
45 ctx_done(ucontext_t *ucp)
48 if (ucp->uc_link == NULL)
51 setcontext((const ucontext_t *)ucp->uc_link);
56 __weak_reference(__makecontext, makecontext);
59 __makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
61 __greg_t *gr = ucp->uc_mcontext.__gregs;
66 /* Compute and align stack pointer. */
68 (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size -
69 sizeof(double)) & ~7);
70 /* Allocate necessary stack space for arguments exceeding r0-3. */
73 gr[_REG_SP] = (__greg_t)sp;
74 /* Wipe out frame pointer. */
76 /* Arrange for return via the trampoline code. */
77 gr[_REG_PC] = (__greg_t)_ctx_start;
78 gr[_REG_R4] = (__greg_t)func;
79 gr[_REG_R5] = (__greg_t)ucp;
82 /* Pass up to four arguments in r0-3. */
83 for (i = 0; i < argc && i < 4; i++)
84 gr[_REG_R0 + i] = va_arg(ap, int);
85 /* Pass any additional arguments on the stack. */
86 for (argc -= i; argc > 0; argc--)
87 *sp++ = va_arg(ap, int);