688ebe120c
the process of exiting the kernel. The ast() function now loops as long as the PS_ASTPENDING or PS_NEEDRESCHED flags are set. It returns with preemption disabled so that any further AST's that arrive via an interrupt will be delayed until the low-level MD code returns to user mode. - Use u_int's to store the tick counts for profiling purposes so that we do not need sched_lock just to read p_sticks. This also closes a problem where the call to addupc_task() could screw up the arithmetic due to non-atomic reads of p_sticks. - Axe need_proftick(), aston(), astoff(), astpending(), need_resched(), clear_resched(), and resched_wanted() in favor of direct bit operations on p_sflag. - Fix up locking with sched_lock some. In addupc_intr(), use sched_lock to ensure pr_addr and pr_ticks are updated atomically with setting PS_OWEUPC. In ast() we clear pr_ticks atomically with clearing PS_OWEUPC. We also do not grab the lock just to test a flag. - Simplify the handling of Giant in ast() slightly. Reviewed by: bde (mostly)
193 lines
5.6 KiB
C
193 lines
5.6 KiB
C
/*-
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* Copyright (C) 1994, David Greenman
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* the University of Utah, and William Jolitz.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)trap.c 7.4 (Berkeley) 5/13/91
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* $FreeBSD$
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*/
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#ifdef __i386__
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#include "opt_npx.h"
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#endif
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#include <sys/param.h>
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#include <sys/bus.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/signalvar.h>
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#include <sys/systm.h>
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#include <sys/vmmeter.h>
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#include <machine/cpu.h>
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#include <machine/pcb.h>
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/*
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* Define the code needed before returning to user mode, for
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* trap and syscall.
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*/
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void
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userret(p, frame, oticks)
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struct proc *p;
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struct trapframe *frame;
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u_int oticks;
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{
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int sig;
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mtx_lock(&Giant);
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PROC_LOCK(p);
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while ((sig = CURSIG(p)) != 0)
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postsig(sig);
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mtx_unlock(&Giant);
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PROC_UNLOCK(p);
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mtx_lock_spin(&sched_lock);
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p->p_pri.pri_level = p->p_pri.pri_user;
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if (p->p_sflag & PS_NEEDRESCHED) {
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/*
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* Since we are curproc, a clock interrupt could
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* change our priority without changing run queues
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* (the running process is not kept on a run queue).
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* If this happened after we setrunqueue ourselves but
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* before we switch()'ed, we might not be on the queue
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* indicated by our priority.
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*/
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DROP_GIANT_NOSWITCH();
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setrunqueue(p);
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p->p_stats->p_ru.ru_nivcsw++;
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mi_switch();
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mtx_unlock_spin(&sched_lock);
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PICKUP_GIANT();
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mtx_lock(&Giant);
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PROC_LOCK(p);
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while ((sig = CURSIG(p)) != 0)
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postsig(sig);
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mtx_unlock(&Giant);
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PROC_UNLOCK(p);
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} else
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mtx_unlock_spin(&sched_lock);
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/*
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* Charge system time if profiling.
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*/
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if (p->p_sflag & PS_PROFIL)
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addupc_task(p, TRAPF_PC(frame),
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((u_int)p->p_sticks - oticks) * psratio);
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}
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/*
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* Process an asynchronous software trap.
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* This is relatively easy.
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* This function will return with preemption disabled.
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*/
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void
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ast(framep)
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struct trapframe *framep;
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{
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struct proc *p = CURPROC;
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u_int prticks, sticks;
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critical_t s;
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int sflag;
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#if defined(DEV_NPX) && !defined(SMP)
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int ucode;
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#endif
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KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
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#ifdef WITNESS
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if (witness_list(p))
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panic("Returning to user mode with mutex(s) held");
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#endif
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mtx_assert(&Giant, MA_NOTOWNED);
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s = critical_enter();
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while ((p->p_sflag & (PS_ASTPENDING | PS_NEEDRESCHED)) != 0) {
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critical_exit(s);
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p->p_frame = framep;
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/*
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* This updates the p_sflag's for the checks below in one
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* "atomic" operation with turning off the astpending flag.
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* If another AST is triggered while we are handling the
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* AST's saved in sflag, the astpending flag will be set and
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* we will loop again.
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*/
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mtx_lock_spin(&sched_lock);
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sticks = p->p_sticks;
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sflag = p->p_sflag;
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p->p_sflag &= ~(PS_OWEUPC | PS_ALRMPEND | PS_PROFPEND |
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PS_ASTPENDING);
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cnt.v_soft++;
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if (sflag & PS_OWEUPC) {
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prticks = p->p_stats->p_prof.pr_ticks;
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p->p_stats->p_prof.pr_ticks = 0;
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mtx_unlock_spin(&sched_lock);
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addupc_task(p, p->p_stats->p_prof.pr_addr, prticks);
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} else
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mtx_unlock_spin(&sched_lock);
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if (sflag & PS_ALRMPEND) {
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PROC_LOCK(p);
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psignal(p, SIGVTALRM);
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PROC_UNLOCK(p);
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}
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#if defined(DEV_NPX) && !defined(SMP)
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if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
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atomic_clear_char(&PCPU_GET(curpcb)->pcb_flags,
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PCB_NPXTRAP);
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ucode = npxtrap();
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if (ucode != -1) {
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mtx_lock(&Giant);
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trapsignal(p, SIGFPE, ucode);
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}
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}
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#endif
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if (sflag & PS_PROFPEND) {
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PROC_LOCK(p);
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psignal(p, SIGPROF);
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PROC_UNLOCK(p);
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}
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userret(p, framep, sticks);
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if (mtx_owned(&Giant))
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mtx_unlock(&Giant);
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s = critical_enter();
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}
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mtx_assert(&Giant, MA_NOTOWNED);
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/*
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* We need to keep interrupts disabled so that if any further AST's
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* come in, the interrupt they come in on will be delayed until we
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* finish returning to userland. We assume that the return to userland
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* will perform the equivalent of critical_exit().
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*/
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}
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