1 /* $NetBSD: userret.h,v 1.35 2024/01/28 10:06:19 skrll Exp $ */
2
3 /*-
4 * Copyright (c) 1998, 2000, 2003, 2006, 2008, 2019, 2020, 2023
5 * The NetBSD Foundation, Inc.
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to The NetBSD Foundation
9 * by Charles M. Hannum, and Andrew Doran.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #ifndef _SYS_USERRET_H_
34 #define _SYS_USERRET_H_
35
36 #include <sys/lockdebug.h>
37 #include <sys/intr.h>
38 #include <sys/psref.h>
39
40 /*
41 * Define the MI code needed before returning to user mode, for trap and
42 * syscall.
43 *
44 * We handle "exceptional" events: pending signals, stop/exit actions, etc.
45 * Note that the event must be flagged BEFORE any AST is posted as we are
46 * reading unlocked.
47 */
48 static __inline void
mi_userret(struct lwp * l)49 mi_userret(struct lwp *l)
50 {
51 int exception;
52
53 KPREEMPT_DISABLE(l);
54 KASSERTMSG(l->l_cpu->ci_biglock_count == 0, "kernel_lock leaked");
55 KASSERT(l->l_blcnt == 0);
56 exception = l->l_cpu->ci_want_resched | (l->l_flag & LW_USERRET);
57 KPREEMPT_ENABLE(l);
58 if (__predict_false(exception)) {
59 lwp_userret(l);
60 }
61
62 LOCKDEBUG_BARRIER(NULL, 0);
63 KASSERT(l->l_nopreempt == 0);
64 PSREF_DEBUG_BARRIER();
65 KASSERT(l->l_psrefs == 0);
66 }
67
68 #endif /* !_SYS_USERRET_H_ */
69