makecontext.c revision 1.4 1 1.4 martin /* $NetBSD: makecontext.c,v 1.4 2008/04/28 20:22:57 martin Exp $ */
2 1.2 thorpej
3 1.2 thorpej /*-
4 1.2 thorpej * Copyright (c) 2001 The NetBSD Foundation, Inc.
5 1.2 thorpej * All rights reserved.
6 1.2 thorpej *
7 1.2 thorpej * This code is derived from software contributed to The NetBSD Foundation
8 1.2 thorpej * by Klaus Klein.
9 1.2 thorpej *
10 1.2 thorpej * Redistribution and use in source and binary forms, with or without
11 1.2 thorpej * modification, are permitted provided that the following conditions
12 1.2 thorpej * are met:
13 1.2 thorpej * 1. Redistributions of source code must retain the above copyright
14 1.2 thorpej * notice, this list of conditions and the following disclaimer.
15 1.2 thorpej * 2. Redistributions in binary form must reproduce the above copyright
16 1.2 thorpej * notice, this list of conditions and the following disclaimer in the
17 1.2 thorpej * documentation and/or other materials provided with the distribution.
18 1.2 thorpej *
19 1.2 thorpej * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 1.2 thorpej * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 1.2 thorpej * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 1.2 thorpej * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 1.2 thorpej * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 1.2 thorpej * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 1.2 thorpej * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 1.2 thorpej * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 1.2 thorpej * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 1.2 thorpej * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 1.2 thorpej * POSSIBILITY OF SUCH DAMAGE.
30 1.2 thorpej */
31 1.2 thorpej
32 1.2 thorpej #include <sys/cdefs.h>
33 1.2 thorpej #if defined(LIBC_SCCS) && !defined(lint)
34 1.4 martin __RCSID("$NetBSD: makecontext.c,v 1.4 2008/04/28 20:22:57 martin Exp $");
35 1.2 thorpej #endif
36 1.2 thorpej
37 1.2 thorpej #include <inttypes.h>
38 1.2 thorpej #include <stddef.h>
39 1.2 thorpej #include <ucontext.h>
40 1.2 thorpej #include "extern.h"
41 1.2 thorpej
42 1.2 thorpej #if __STDC__
43 1.2 thorpej #include <stdarg.h>
44 1.2 thorpej #else
45 1.2 thorpej #include <varargs.h>
46 1.2 thorpej #endif
47 1.2 thorpej
48 1.2 thorpej void
49 1.2 thorpej makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
50 1.2 thorpej {
51 1.2 thorpej __greg_t *gr = ucp->uc_mcontext.__gregs;
52 1.2 thorpej int *sp;
53 1.2 thorpej int i;
54 1.2 thorpej va_list ap;
55 1.2 thorpej
56 1.2 thorpej /* LINTED uintptr_t is safe */
57 1.2 thorpej sp = (int *)
58 1.2 thorpej ((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
59 1.2 thorpej /* LINTED uintptr_t is safe */
60 1.2 thorpej sp -= 2 + (argc > 8 ? argc - 8: 0); /* Make room for call frame. */
61 1.2 thorpej sp = (int *)
62 1.2 thorpej ((uintptr_t)sp & ~0xf); /* Align on quad-word boundary. */
63 1.2 thorpej
64 1.2 thorpej /*
65 1.2 thorpej * Start executing at <func> -- when <func> completes, return to
66 1.2 thorpej * <_resumecontext>.
67 1.2 thorpej */
68 1.3 kleink gr[_REG_R1] = (__greg_t)sp;
69 1.3 kleink gr[_REG_LR] = (__greg_t)_resumecontext;
70 1.3 kleink gr[_REG_PC] = (__greg_t)func;
71 1.2 thorpej
72 1.2 thorpej /* Wipe out stack frame backchain pointer. */
73 1.2 thorpej *sp = 0;
74 1.2 thorpej
75 1.2 thorpej /* Construct argument list. */
76 1.2 thorpej va_start(ap, argc);
77 1.2 thorpej /* Up to the first eight arguments are passed in r3-10. */
78 1.2 thorpej for (i = 0; i < argc && i < 8; i++)
79 1.3 kleink gr[_REG_R3 + i] = va_arg(ap, int);
80 1.2 thorpej /* Pass remaining arguments on the stack above the backchain/lr gap. */
81 1.2 thorpej for (sp += 2; i < argc; i++)
82 1.2 thorpej *sp++ = va_arg(ap, int);
83 1.2 thorpej va_end(ap);
84 1.2 thorpej }
85