1/*	$NetBSD: makecontext.c,v 1.5 2011/09/20 08:42:29 joerg 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 *
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.
30 */
31
32#include <sys/cdefs.h>
33#if defined(LIBC_SCCS) && !defined(lint)
34__RCSID("$NetBSD: makecontext.c,v 1.5 2011/09/20 08:42:29 joerg Exp $");
35#endif
36
37#include <inttypes.h>
38#include <stddef.h>
39#include <ucontext.h>
40#include "extern.h"
41
42#include <stdarg.h>
43
44#include <sys/types.h>
45#include <machine/frame.h>
46
47void __resumecontext(void) __dead;
48
49void
50makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
51{
52	__greg_t *gr = ucp->uc_mcontext.__gregs;
53	__greg_t *gp, rp, fp;
54	register __greg_t dp __asm("r27");
55	uintptr_t *sp;
56	int i;
57	va_list ap;
58
59	/* LINTED uintptr_t is safe */
60	sp  = (uintptr_t *)ucp->uc_stack.ss_sp;
61	/* LINTED uintptr_t is safe */
62	sp += 16;			/* standard frame */
63	sp += (argc >= 4 ? argc : 4);	/* Make room for >=4 arguments. */
64	sp  = (uintptr_t *)
65	      ((uintptr_t)(sp + 16) & ~0x3f);	/* Align on 64-byte boundary. */
66
67	/* Save away the registers that we'll need. */
68	gr[_REG_SP] = (__greg_t)sp;
69	rp = (__greg_t)__resumecontext;
70	if (rp & 2) {
71		gp = (__greg_t *)(rp & ~3);
72		rp = gp[0];
73		sp[-8] = gp[1];
74	}
75	gr[_REG_RP] = rp;
76	fp = (__greg_t)func;
77	if (fp & 2) {
78		gp = (__greg_t *)(fp & ~3);
79		fp = gp[0];
80		gr[_REG_R19] = gp[1];
81	}
82	gr[_REG_PCOQH] = fp | HPPA_PC_PRIV_USER;
83	gr[_REG_PCOQT] = (fp + 4) | HPPA_PC_PRIV_USER;
84	/* LINTED dp is reg27, ref. above, so initialized */
85	gr[_REG_DP] = dp;
86
87	/* Construct argument list. */
88	va_start(ap, argc);
89	/* Up to the first four arguments are passed in %arg0-3. */
90	for (i = 0; i < argc && i < 4; i++) {
91		/* LINTED uintptr_t is safe */
92		gr[_REG_ARG0 - i] = va_arg(ap, uintptr_t);
93	}
94	/* Pass remaining arguments on the stack below the %arg0-3 gap. */
95	for (; i < argc; i++) {
96		/* LINTED uintptr_t is safe */
97		sp[-9 - i] = va_arg(ap, uintptr_t);
98	}
99	va_end(ap);
100}
101