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230 lines
6.9 KiB
C
230 lines
6.9 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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* MPSAFE
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*/
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void
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userret(td, frame, oticks)
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struct thread *td;
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struct trapframe *frame;
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u_int oticks;
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{
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struct proc *p = td->td_proc;
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struct kse *ke = td->td_kse;
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struct ksegrp *kg = td->td_ksegrp;
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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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PROC_UNLOCK(p);
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mtx_unlock(&Giant);
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mtx_lock_spin(&sched_lock);
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td->td_priority = kg->kg_user_pri;
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if (ke->ke_flags & KEF_NEEDRESCHED) {
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DROP_GIANT();
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setrunqueue(td);
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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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mtx_lock_spin(&sched_lock);
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}
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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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quad_t ticks;
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ticks = ke->ke_sticks - oticks;
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mtx_unlock_spin(&sched_lock);
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addupc_task(ke, TRAPF_PC(frame), (u_int)ticks * psratio);
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} else
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mtx_unlock_spin(&sched_lock);
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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 thread *td = curthread;
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struct proc *p = td->td_proc;
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struct kse *ke = td->td_kse;
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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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int flags;
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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(td))
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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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prticks = 0; /* XXX: Quiet warning. */
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s = cpu_critical_enter();
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while ((ke->ke_flags & (KEF_ASTPENDING | KEF_NEEDRESCHED)) != 0) {
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cpu_critical_exit(s);
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td->td_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 = ke->ke_sticks;
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sflag = p->p_sflag;
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flags = ke->ke_flags;
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p->p_sflag &= ~(PS_PROFPEND | PS_ALRMPEND);
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ke->ke_flags &= ~(KEF_OWEUPC | KEF_ASTPENDING);
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cnt.v_soft++;
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if (flags & KEF_OWEUPC && sflag & PS_PROFIL) {
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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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}
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mtx_unlock_spin(&sched_lock);
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#ifdef DIAGNOSTIC
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/*
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* As a diagnostic tool we make sure that td->td_ucred
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* is NULL while we are in user space. This is
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* because theoreticaly this field is only defined
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* while the thread is in the kernel. Making it NULL
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* will immediatly trap invalid usage of this field.
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* In practice however we keep the reference to the ucred
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* because it's almost always going to be the same cred we will
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* need at the next syscall, and it can be expensive
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* to keep dropping and reacquiring the reference.
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* We thus stash it away elsewhere until we return
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* to the kernel, where we bring it back. If
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* DIAGNOSTIC is not defined we don't bother with
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* making it NULL, and just leave it in place.
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* (don't remove this comment without removing the pointers
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* to it in sys/proc.h, trap.c, kern/kern_fork.c and here.)
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*/
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if (td->td_ucred)
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panic("ast:thread got a cred before reaching AST");
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td->td_ucred = td->td_ucred_cache;
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td->td_ucred_cache = NULL;
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#endif /* DIAGNOSTIC */
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if (td->td_ucred != p->p_ucred)
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cred_update_thread(td);
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if (flags & KEF_OWEUPC && sflag & PS_PROFIL)
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addupc_task(ke, p->p_stats->p_prof.pr_addr, prticks);
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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_int(&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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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(td, framep, sticks);
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#ifdef DIAGNOSTIC /* see comment above */
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if (td->td_ucred_cache)
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panic("ast:thread already has cached ucred");
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td->td_ucred_cache = td->td_ucred;
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td->td_ucred = NULL;
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#endif /* DIAGNOSTIC */
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s = cpu_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 cpu_critical_exit().
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*/
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}
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