makecontext.c revision 1.2 
1/*	$NetBSD: makecontext.c,v 1.2 2005/12/24 21:41:01 perry 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 * 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.
25 *
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.
37 */
38
39#include <sys/cdefs.h>
40#if defined(LIBC_SCCS) && !defined(lint)
41__RCSID("$NetBSD: makecontext.c,v 1.2 2005/12/24 21:41:01 perry Exp $");
42#endif
43
44#include <inttypes.h>
45#include <stddef.h>
46#include <ucontext.h>
47#include "extern.h"
48
49#include <stdarg.h>
50
51#include <sys/types.h>
52#include <machine/frame.h>
53
54void
55makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
56{
57	__greg_t *gr = ucp->uc_mcontext.__gregs;
58	__greg_t *gp, rp, fp;
59	register __greg_t dp __asm("r27");
60	uintptr_t *sp;
61	int i;
62	va_list ap;
63
64	void __resumecontext(void);
65
66	/* LINTED uintptr_t is safe */
67	sp  = (uintptr_t *)ucp->uc_stack.ss_sp;
68	/* LINTED uintptr_t is safe */
69	sp += 16;			/* standard frame */
70	sp += (argc >= 4 ? argc : 4);	/* Make room for >=4 arguments. */
71	sp  = (uintptr_t *)
72	      ((uintptr_t)(sp + 16) & ~0x3f);	/* Align on 64-byte boundary. */
73
74	/* Save away the registers that we'll need. */
75	gr[_REG_SP] = (__greg_t)sp;
76	rp = (__greg_t)__resumecontext;
77	if (rp & 2) {
78		gp = (__greg_t *)(rp & ~3);
79		rp = gp[0];
80		sp[-8] = gp[1];
81	}
82	gr[_REG_RP] = rp;
83	fp = (__greg_t)func;
84	if (fp & 2) {
85		gp = (__greg_t *)(fp & ~3);
86		fp = gp[0];
87		gr[_REG_R19] = gp[1];
88	}
89	gr[_REG_PCOQH] = fp | HPPA_PC_PRIV_USER;
90	gr[_REG_PCOQT] = (fp + 4) | HPPA_PC_PRIV_USER;
91	gr[_REG_DP] = dp;
92
93	/* Construct argument list. */
94	va_start(ap, argc);
95	/* Up to the first four arguments are passed in %arg0-3. */
96	for (i = 0; i < argc && i < 4; i++) {
97		/* LINTED uintptr_t is safe */
98		gr[_REG_ARG0 - i] = va_arg(ap, uintptr_t);
99	}
100	/* Pass remaining arguments on the stack below the %arg0-3 gap. */
101	for (; i < argc; i++) {
102		/* LINTED uintptr_t is safe */
103		sp[-9 - i] = va_arg(ap, uintptr_t);
104	}
105	va_end(ap);
106}
107