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userret.h
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userret.h
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/* $NetBSD: userret.h,v 1.33 2020/03/26 20:19:06 ad Exp $ */
/*-
* Copyright (c) 1998, 2000, 2003, 2006, 2008, 2019, 2020
* The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum, and Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#ifndef _SYS_USERRET_H_
#define _SYS_USERRET_H_
#include <sys/lockdebug.h>
#include <sys/intr.h>
#include <sys/psref.h>
/*
* Define the MI code needed before returning to user mode, for trap and
* syscall.
*
* We handle "exceptional" events: pending signals, stop/exit actions, etc.
* Note that the event must be flagged BEFORE any AST is posted as we are
* reading unlocked.
*/
static __inline void
mi_userret(struct lwp *l)
{
struct cpu_info *ci;
KPREEMPT_DISABLE(l);
ci = l->l_cpu;
KASSERTMSG(ci->ci_biglock_count == 0, "kernel_lock leaked");
KASSERT(l->l_blcnt == 0);
if (__predict_false(ci->ci_want_resched)) {
preempt();
ci = l->l_cpu;
}
if (__predict_false(l->l_flag & LW_USERRET)) {
KPREEMPT_ENABLE(l);
lwp_userret(l);
KPREEMPT_DISABLE(l);
ci = l->l_cpu;
}
/*
* lwp_eprio() is too involved to use here unlocked. At this point
* it only matters for PTHREAD_PRIO_PROTECT; setting a too low value
* is OK because the scheduler will find out the true value if we
* end up in mi_switch().
*
* This is being called on every syscall and trap, and remote CPUs
* regularly look at ci_schedstate. Keep the cache line in the
* SHARED state by only updating spc_curpriority if it has changed.
*/
l->l_kpriority = false;
if (ci->ci_schedstate.spc_curpriority != l->l_priority) {
ci->ci_schedstate.spc_curpriority = l->l_priority;
}
KPREEMPT_ENABLE(l);
LOCKDEBUG_BARRIER(NULL, 0);
KASSERT(l->l_nopreempt == 0);
PSREF_DEBUG_BARRIER();
KASSERT(l->l_psrefs == 0);
}
#endif /* !_SYS_USERRET_H_ */