Home | History | Annotate | Line # | Download | only in sys 
      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
     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