The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_trap.c

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    1 /*-
    2  * Copyright (C) 1994, David Greenman
    3  * Copyright (c) 1990, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * the University of Utah, and William Jolitz.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. All advertising materials mentioning features or use of this software
   18  *    must display the following acknowledgement:
   19  *      This product includes software developed by the University of
   20  *      California, Berkeley and its contributors.
   21  * 4. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      from: @(#)trap.c        7.4 (Berkeley) 5/13/91
   38  * $FreeBSD: releng/5.0/sys/kern/subr_trap.c 106655 2002-11-08 19:00:17Z rwatson $
   39  */
   40 
   41 #include "opt_mac.h"
   42 #ifdef __i386__
   43 #include "opt_npx.h"
   44 #endif
   45 
   46 #include <sys/param.h>
   47 #include <sys/bus.h>
   48 #include <sys/kernel.h>
   49 #include <sys/lock.h>
   50 #include <sys/mac.h>
   51 #include <sys/mutex.h>
   52 #include <sys/proc.h>
   53 #include <sys/kse.h>
   54 #include <sys/ktr.h>
   55 #include <sys/resourcevar.h>
   56 #include <sys/sched.h>
   57 #include <sys/signalvar.h>
   58 #include <sys/systm.h>
   59 #include <sys/vmmeter.h>
   60 #include <machine/cpu.h>
   61 #include <machine/pcb.h>
   62 
   63 /*
   64  * Define the code needed before returning to user mode, for
   65  * trap and syscall.
   66  *
   67  * MPSAFE
   68  */
   69 void
   70 userret(td, frame, oticks)
   71         struct thread *td;
   72         struct trapframe *frame;
   73         u_int oticks;
   74 {
   75         struct proc *p = td->td_proc;
   76         struct kse *ke = td->td_kse; 
   77 
   78         CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
   79             p->p_comm);
   80 #ifdef INVARIANTS
   81         /* Check that we called signotify() enough. */
   82         mtx_lock(&Giant);
   83         PROC_LOCK(p);
   84         mtx_lock_spin(&sched_lock);
   85         if (SIGPENDING(p) && ((p->p_sflag & PS_NEEDSIGCHK) == 0 ||
   86             (td->td_kse->ke_flags & KEF_ASTPENDING) == 0))
   87                 printf("failed to set signal flags properly for ast()\n");
   88         mtx_unlock_spin(&sched_lock);
   89         PROC_UNLOCK(p);
   90         mtx_unlock(&Giant);
   91 #endif
   92 
   93         /*
   94          * Let the scheduler adjust our priority etc.
   95          */
   96         sched_userret(td);
   97 
   98         /*
   99          * We need to check to see if we have to exit or wait due to a
  100          * single threading requirement or some other STOP condition.
  101          * Don't bother doing all the work if the stop bits are not set
  102          * at this time.. If we miss it, we miss it.. no big deal.
  103          */
  104         if (P_SHOULDSTOP(p)) {
  105                 PROC_LOCK(p);
  106                 thread_suspend_check(0);        /* Can suspend or kill */
  107                 PROC_UNLOCK(p);
  108         }
  109 
  110         /*
  111          * Do special thread processing, e.g. upcall tweaking and such.
  112          */
  113         if (p->p_flag & P_KSES) {
  114                 thread_userret(td, frame);
  115                 /* printf("KSE thread returned"); */
  116         }
  117 
  118         /*
  119          * Charge system time if profiling.
  120          *
  121          * XXX should move PS_PROFIL to a place that can obviously be
  122          * accessed safely without sched_lock.
  123          */
  124         if (p->p_sflag & PS_PROFIL) {
  125                 quad_t ticks;
  126 
  127                 mtx_lock_spin(&sched_lock);
  128                 ticks = ke->ke_sticks - oticks;
  129                 mtx_unlock_spin(&sched_lock);
  130                 addupc_task(ke, TRAPF_PC(frame), (u_int)ticks * psratio);
  131         }
  132 }
  133 
  134 /*
  135  * Process an asynchronous software trap.
  136  * This is relatively easy.
  137  * This function will return with preemption disabled.
  138  */
  139 void
  140 ast(struct trapframe *framep)
  141 {
  142         struct thread *td;
  143         struct proc *p;
  144         struct kse *ke;
  145         struct ksegrp *kg;
  146         struct rlimit *rlim;
  147         u_int prticks, sticks;
  148         int sflag;
  149         int flags;
  150         int sig;
  151 #if defined(DEV_NPX) && !defined(SMP)
  152         int ucode;
  153 #endif
  154 
  155         td = curthread;
  156         p = td->td_proc;
  157         kg = td->td_ksegrp;
  158 
  159         CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
  160             p->p_comm);
  161         KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
  162 #ifdef WITNESS
  163         if (witness_list(td))
  164                 panic("Returning to user mode with mutex(s) held");
  165 #endif
  166         mtx_assert(&Giant, MA_NOTOWNED);
  167         mtx_assert(&sched_lock, MA_NOTOWNED);
  168         td->td_frame = framep;
  169 
  170         /*
  171          * This updates the p_sflag's for the checks below in one
  172          * "atomic" operation with turning off the astpending flag.
  173          * If another AST is triggered while we are handling the
  174          * AST's saved in sflag, the astpending flag will be set and
  175          * ast() will be called again.
  176          */
  177         mtx_lock_spin(&sched_lock);
  178         ke = td->td_kse;
  179         sticks = ke->ke_sticks;
  180         flags = ke->ke_flags;
  181         sflag = p->p_sflag;
  182         p->p_sflag &= ~(PS_ALRMPEND | PS_NEEDSIGCHK | PS_PROFPEND | PS_XCPU);
  183 #ifdef MAC
  184         p->p_sflag &= ~PS_MACPEND;
  185 #endif
  186         ke->ke_flags &= ~(KEF_ASTPENDING | KEF_NEEDRESCHED | KEF_OWEUPC);
  187         cnt.v_soft++;
  188         prticks = 0;
  189         if (flags & KEF_OWEUPC && sflag & PS_PROFIL) {
  190                 prticks = p->p_stats->p_prof.pr_ticks;
  191                 p->p_stats->p_prof.pr_ticks = 0;
  192         }
  193         mtx_unlock_spin(&sched_lock);
  194         /*
  195          * XXXKSE While the fact that we owe a user profiling
  196          * tick is stored per KSE in this code, the statistics
  197          * themselves are still stored per process.
  198          * This should probably change, by which I mean that
  199          * possibly the location of both might change.
  200          */
  201 
  202         if (td->td_ucred != p->p_ucred) 
  203                 cred_update_thread(td);
  204         if (flags & KEF_OWEUPC && sflag & PS_PROFIL)
  205                 addupc_task(ke, p->p_stats->p_prof.pr_addr, prticks);
  206         if (sflag & PS_ALRMPEND) {
  207                 PROC_LOCK(p);
  208                 psignal(p, SIGVTALRM);
  209                 PROC_UNLOCK(p);
  210         }
  211 #if defined(DEV_NPX) && !defined(SMP)
  212         if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
  213                 atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
  214                     PCB_NPXTRAP);
  215                 ucode = npxtrap();
  216                 if (ucode != -1) {
  217                         trapsignal(p, SIGFPE, ucode);
  218                 }
  219         }
  220 #endif
  221         if (sflag & PS_PROFPEND) {
  222                 PROC_LOCK(p);
  223                 psignal(p, SIGPROF);
  224                 PROC_UNLOCK(p);
  225         }
  226         if (sflag & PS_XCPU) {
  227                 PROC_LOCK(p);
  228                 rlim = &p->p_rlimit[RLIMIT_CPU];
  229                 if (p->p_runtime.sec >= rlim->rlim_max)
  230                         killproc(p, "exceeded maximum CPU limit");
  231                 else {
  232                         psignal(p, SIGXCPU);
  233                         mtx_lock_spin(&sched_lock);
  234                         if (p->p_cpulimit < rlim->rlim_max)
  235                                 p->p_cpulimit += 5;
  236                         mtx_unlock_spin(&sched_lock);
  237                 }
  238                 PROC_UNLOCK(p);
  239         }
  240 #ifdef MAC
  241         if (sflag & PS_MACPEND)
  242                 mac_thread_userret(td);
  243 #endif
  244         if (flags & KEF_NEEDRESCHED) {
  245                 mtx_lock_spin(&sched_lock);
  246                 sched_prio(td, kg->kg_user_pri);
  247                 p->p_stats->p_ru.ru_nivcsw++;
  248                 mi_switch();
  249                 mtx_unlock_spin(&sched_lock);
  250         }
  251         if (sflag & PS_NEEDSIGCHK) {
  252                 PROC_LOCK(p);
  253                 while ((sig = cursig(td)) != 0)
  254                         postsig(sig);
  255                 PROC_UNLOCK(p);
  256         }
  257 
  258         userret(td, framep, sticks);
  259 #ifdef DIAGNOSTIC
  260         cred_free_thread(td);
  261 #endif
  262         mtx_assert(&Giant, MA_NOTOWNED);
  263 }

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