1 /* $NetBSD: makecontext.c,v 1.8 2025/04/25 01:18:51 riastradh 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 1.8 2025/04/25 01:18:51 riastradh Exp $");
35 #endif
36
37 #include <sys/param.h>
38 #include <sys/types.h>
39
40 #include <machine/frame.h>
41
42 #include <inttypes.h>
43 #include <stdarg.h>
44 #include <stddef.h>
45 #include <ucontext.h>
46
47 #include "extern.h"
48
49 void __resumecontext(void) __dead;
50
51 void
makecontext(ucontext_t * ucp,void (* func)(void),int argc,...)52 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
53 {
54 __greg_t *gr = ucp->uc_mcontext.__gregs;
55 __greg_t *gp, rp, fp;
56 register __greg_t dp __asm("r27");
57 uintptr_t *sp;
58 int i;
59 va_list ap;
60
61 /* LINTED uintptr_t is safe */
62 sp = (uintptr_t *)ucp->uc_stack.ss_sp;
63 /* LINTED uintptr_t is safe */
64 sp += 16; /* standard frame */
65 sp += (argc >= 4 ? argc : 4); /* Make room for >=4 arguments. */
66 sp = (uintptr_t *) /* Align on 64-byte boundary. */
67 (((uintptr_t)sp + STACK_ALIGNBYTES) & ~STACK_ALIGNBYTES);
68
69 /* Save away the registers that we'll need. */
70 gr[_REG_SP] = (__greg_t)sp;
71 rp = (__greg_t)__resumecontext;
72 if (rp & 2) {
73 gp = (__greg_t *)(rp & ~3);
74 rp = gp[0];
75 sp[-8] = gp[1];
76 }
77 gr[_REG_RP] = rp;
78 fp = (__greg_t)func;
79 if (fp & 2) {
80 gp = (__greg_t *)(fp & ~3);
81 fp = gp[0];
82 gr[_REG_R19] = gp[1];
83 }
84 gr[_REG_PCOQH] = fp | HPPA_PC_PRIV_USER;
85 gr[_REG_PCOQT] = (fp + 4) | HPPA_PC_PRIV_USER;
86 /* LINTED dp is reg27, ref. above, so initialized */
87 gr[_REG_DP] = dp;
88
89 /* Construct argument list. */
90 va_start(ap, argc);
91 /* Up to the first four arguments are passed in %arg0-3. */
92 for (i = 0; i < argc && i < 4; i++) {
93 /* LINTED uintptr_t is safe */
94 gr[_REG_ARG0 - i] = va_arg(ap, uintptr_t);
95 }
96 /* Pass remaining arguments on the stack below the %arg0-3 gap. */
97 for (; i < argc; i++) {
98 /* LINTED uintptr_t is safe */
99 sp[-9 - i] = va_arg(ap, uintptr_t);
100 }
101 va_end(ap);
102 }
103