1 /* $NetBSD: _lwp.c,v 1.4 2023/04/02 07:26:18 skrll Exp $ */
2
3 /*-
4 * Copyright (c) 2009 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas
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: _lwp.c,v 1.4 2023/04/02 07:26:18 skrll Exp $");
35 #endif /* LIBC_SCCS and not lint */
36
37 #include "namespace.h"
38 #include <sys/types.h>
39 #include <inttypes.h>
40 #include <ucontext.h>
41 #include <lwp.h>
42 #include <stdlib.h>
43
44 void
_lwp_makecontext(ucontext_t * u,void (* start)(void *),void * arg,void * private,caddr_t stack_base,size_t stack_size)45 _lwp_makecontext(ucontext_t *u, void (*start)(void *),
46 void *arg, void *private, caddr_t stack_base, size_t stack_size)
47 {
48 __greg_t *gr = u->uc_mcontext.__gregs;
49 int *sp;
50
51 getcontext(u);
52 u->uc_link = NULL;
53
54 u->uc_stack.ss_sp = stack_base;
55 u->uc_stack.ss_size = stack_size;
56
57 /* Align to a word */
58 /* LINTED uintptr_t is safe */
59 sp = (int *)((uintptr_t)(stack_base + stack_size) & ~0x3);
60
61 /*
62 * Allocate necessary stack space for arguments including arg count
63 * and call frame
64 */
65 sp -= 1 + 1 + 5;
66
67 sp[0] = 0; /* condition handler is null */
68 sp[1] = 0x20000000; /* make this a CALLS frame */
69 sp[2] = 0; /* saved argument pointer */
70 sp[3] = 0; /* saved frame pointer */
71 sp[4] = (int)(uintptr_t)_lwp_exit + 2;/* return via _lwp_exit */
72 sp[5] = 1; /* argc */
73 sp[6] = (int)(uintptr_t)arg; /* argv */
74
75 gr[_REG_AP] = (__greg_t)(uintptr_t)(sp + 5);
76 gr[_REG_SP] = (__greg_t)(uintptr_t)sp;
77 gr[_REG_FP] = (__greg_t)(uintptr_t)sp;
78 gr[_REG_PC] = (__greg_t)(uintptr_t)start + 2;
79
80 /*
81 * Push the TLS pointer onto the new stack also.
82 * The _UC_TLSBASE flag tells the kernel to pop it and use it.
83 */
84 *--sp = (int)(intptr_t)private;
85 gr[_REG_SP] = (__greg_t)(uintptr_t)sp;
86 u->uc_flags |= _UC_TLSBASE;
87 }
88