1*0a6a1f1dSLionel Sambuc /* $NetBSD: makecontext.c,v 1.1 2014/08/10 05:47:36 matt Exp $ */
2*0a6a1f1dSLionel Sambuc
3*0a6a1f1dSLionel Sambuc /*-
4*0a6a1f1dSLionel Sambuc * Copyright (c) 2014 The NetBSD Foundation, Inc.
5*0a6a1f1dSLionel Sambuc * All rights reserved.
6*0a6a1f1dSLionel Sambuc *
7*0a6a1f1dSLionel Sambuc * This code is derived from software contributed to The NetBSD Foundation
8*0a6a1f1dSLionel Sambuc * by Matt Thomas of 3am Software Foundry.
9*0a6a1f1dSLionel Sambuc *
10*0a6a1f1dSLionel Sambuc * Redistribution and use in source and binary forms, with or without
11*0a6a1f1dSLionel Sambuc * modification, are permitted provided that the following conditions
12*0a6a1f1dSLionel Sambuc * are met:
13*0a6a1f1dSLionel Sambuc * 1. Redistributions of source code must retain the above copyright
14*0a6a1f1dSLionel Sambuc * notice, this list of conditions and the following disclaimer.
15*0a6a1f1dSLionel Sambuc * 2. Redistributions in binary form must reproduce the above copyright
16*0a6a1f1dSLionel Sambuc * notice, this list of conditions and the following disclaimer in the
17*0a6a1f1dSLionel Sambuc * documentation and/or other materials provided with the distribution.
18*0a6a1f1dSLionel Sambuc *
19*0a6a1f1dSLionel Sambuc * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20*0a6a1f1dSLionel Sambuc * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21*0a6a1f1dSLionel Sambuc * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22*0a6a1f1dSLionel Sambuc * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23*0a6a1f1dSLionel Sambuc * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24*0a6a1f1dSLionel Sambuc * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25*0a6a1f1dSLionel Sambuc * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26*0a6a1f1dSLionel Sambuc * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27*0a6a1f1dSLionel Sambuc * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28*0a6a1f1dSLionel Sambuc * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29*0a6a1f1dSLionel Sambuc * POSSIBILITY OF SUCH DAMAGE.
30*0a6a1f1dSLionel Sambuc */
31*0a6a1f1dSLionel Sambuc
32*0a6a1f1dSLionel Sambuc #include <sys/cdefs.h>
33*0a6a1f1dSLionel Sambuc #if defined(LIBC_SCCS) && !defined(lint)
34*0a6a1f1dSLionel Sambuc __RCSID("$NetBSD: makecontext.c,v 1.1 2014/08/10 05:47:36 matt Exp $");
35*0a6a1f1dSLionel Sambuc #endif
36*0a6a1f1dSLionel Sambuc
37*0a6a1f1dSLionel Sambuc #include <stddef.h>
38*0a6a1f1dSLionel Sambuc #include <inttypes.h>
39*0a6a1f1dSLionel Sambuc #include <ucontext.h>
40*0a6a1f1dSLionel Sambuc #include "extern.h"
41*0a6a1f1dSLionel Sambuc
42*0a6a1f1dSLionel Sambuc #include <stdarg.h>
43*0a6a1f1dSLionel Sambuc
44*0a6a1f1dSLionel Sambuc void
makecontext(ucontext_t * ucp,void (* func)(void),int argc,...)45*0a6a1f1dSLionel Sambuc makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
46*0a6a1f1dSLionel Sambuc {
47*0a6a1f1dSLionel Sambuc __greg_t * const gr = ucp->uc_mcontext.__gregs;
48*0a6a1f1dSLionel Sambuc __uint64_t *sp;
49*0a6a1f1dSLionel Sambuc
50*0a6a1f1dSLionel Sambuc /* Compute and align stack pointer. */
51*0a6a1f1dSLionel Sambuc sp = (uint64_t *)
52*0a6a1f1dSLionel Sambuc (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & -16LL);
53*0a6a1f1dSLionel Sambuc /* Allocate necessary stack space for arguments exceeding x0-7. */
54*0a6a1f1dSLionel Sambuc if (argc > 8)
55*0a6a1f1dSLionel Sambuc sp -= argc - 8;
56*0a6a1f1dSLionel Sambuc gr[_REG_SP] = (__greg_t)(uintptr_t)sp;
57*0a6a1f1dSLionel Sambuc /* Wipe out frame pointer. */
58*0a6a1f1dSLionel Sambuc gr[_REG_X29] = 0;
59*0a6a1f1dSLionel Sambuc /* Arrange for return via the trampoline code. */
60*0a6a1f1dSLionel Sambuc gr[_REG_X30] = (__greg_t)(uintptr_t)_resumecontext;
61*0a6a1f1dSLionel Sambuc gr[_REG_PC] = (__greg_t)(uintptr_t)func;
62*0a6a1f1dSLionel Sambuc
63*0a6a1f1dSLionel Sambuc va_list ap;
64*0a6a1f1dSLionel Sambuc va_start(ap, argc);
65*0a6a1f1dSLionel Sambuc
66*0a6a1f1dSLionel Sambuc /* Pass up to four arguments in r0-3. */
67*0a6a1f1dSLionel Sambuc for (int i = 0; i < argc && i < 8; i++) {
68*0a6a1f1dSLionel Sambuc gr[_REG_X0 + i] = va_arg(ap, int);
69*0a6a1f1dSLionel Sambuc }
70*0a6a1f1dSLionel Sambuc
71*0a6a1f1dSLionel Sambuc /* Pass any additional arguments on the stack. */
72*0a6a1f1dSLionel Sambuc for (int i = 8; i < argc; i++) {
73*0a6a1f1dSLionel Sambuc *sp++ = va_arg(ap, uint64_t);
74*0a6a1f1dSLionel Sambuc }
75*0a6a1f1dSLionel Sambuc va_end(ap);
76*0a6a1f1dSLionel Sambuc }
77