makecontext.c revision 1.4 
1/*	$NetBSD: makecontext.c,v 1.4 2011/09/19 21:24:57 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 1.4 2011/09/19 21:24:57 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
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	/* LINTED uintptr_t is safe */
58	sp  = (uintptr_t *)ucp->uc_stack.ss_sp;
59	/* LINTED uintptr_t is safe */
60	sp += 16;			/* standard frame */
61	sp += (argc >= 4 ? argc : 4);	/* Make room for >=4 arguments. */
62	sp  = (uintptr_t *)
63	      ((uintptr_t)(sp + 16) & ~0x3f);	/* Align on 64-byte boundary. */
64
65	/* Save away the registers that we'll need. */
66	gr[_REG_SP] = (__greg_t)sp;
67	rp = (__greg_t)__resumecontext;
68	if (rp & 2) {
69		gp = (__greg_t *)(rp & ~3);
70		rp = gp[0];
71		sp[-8] = gp[1];
72	}
73	gr[_REG_RP] = rp;
74	fp = (__greg_t)func;
75	if (fp & 2) {
76		gp = (__greg_t *)(fp & ~3);
77		fp = gp[0];
78		gr[_REG_R19] = gp[1];
79	}
80	gr[_REG_PCOQH] = fp | HPPA_PC_PRIV_USER;
81	gr[_REG_PCOQT] = (fp + 4) | HPPA_PC_PRIV_USER;
82	gr[_REG_DP] = dp;
83
84	/* Construct argument list. */
85	va_start(ap, argc);
86	/* Up to the first four arguments are passed in %arg0-3. */
87	for (i = 0; i < argc && i < 4; i++) {
88		/* LINTED uintptr_t is safe */
89		gr[_REG_ARG0 - i] = va_arg(ap, uintptr_t);
90	}
91	/* Pass remaining arguments on the stack below the %arg0-3 gap. */
92	for (; i < argc; i++) {
93		/* LINTED uintptr_t is safe */
94		sp[-9 - i] = va_arg(ap, uintptr_t);
95	}
96	va_end(ap);
97}
98