makecontext.c revision 1.3 
1/*	$NetBSD: makecontext.c,v 1.3 2008/04/28 20:22:56 martin 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 1.3 2008/04/28 20:22:56 martin 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
48makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
49{
50	__greg_t *gr = ucp->uc_mcontext.__gregs;
51	__greg_t *gp, rp, fp;
52	register __greg_t dp __asm("r27");
53	uintptr_t *sp;
54	int i;
55	va_list ap;
56
57	void __resumecontext(void);
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	gr[_REG_DP] = dp;
85
86	/* Construct argument list. */
87	va_start(ap, argc);
88	/* Up to the first four arguments are passed in %arg0-3. */
89	for (i = 0; i < argc && i < 4; i++) {
90		/* LINTED uintptr_t is safe */
91		gr[_REG_ARG0 - i] = va_arg(ap, uintptr_t);
92	}
93	/* Pass remaining arguments on the stack below the %arg0-3 gap. */
94	for (; i < argc; i++) {
95		/* LINTED uintptr_t is safe */
96		sp[-9 - i] = va_arg(ap, uintptr_t);
97	}
98	va_end(ap);
99}
100