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  */
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD$");
   42 
   43 #include "opt_ktrace.h"
   44 #include "opt_mac.h"
   45 #ifdef __i386__
   46 #include "opt_npx.h"
   47 #endif
   48 
   49 #include <sys/param.h>
   50 #include <sys/bus.h>
   51 #include <sys/kernel.h>
   52 #include <sys/lock.h>
   53 #include <sys/mac.h>
   54 #include <sys/mutex.h>
   55 #include <sys/proc.h>
   56 #include <sys/ktr.h>
   57 #include <sys/resourcevar.h>
   58 #include <sys/sched.h>
   59 #include <sys/signalvar.h>
   60 #include <sys/systm.h>
   61 #include <sys/vmmeter.h>
   62 #ifdef KTRACE
   63 #include <sys/uio.h>
   64 #include <sys/ktrace.h>
   65 #endif
   66 
   67 #include <machine/cpu.h>
   68 #include <machine/pcb.h>
   69 
   70 /*
   71  * Define the code needed before returning to user mode, for
   72  * trap and syscall.
   73  *
   74  * MPSAFE
   75  */
   76 void
   77 userret(td, frame, oticks)
   78         struct thread *td;
   79         struct trapframe *frame;
   80         u_int oticks;
   81 {
   82         struct proc *p = td->td_proc;
   83 
   84         CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
   85             p->p_comm);
   86 #ifdef DIAGNOSTIC
   87         /* Check that we called signotify() enough. */
   88         PROC_LOCK(p);
   89         mtx_lock_spin(&sched_lock);
   90         if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
   91             (td->td_flags & TDF_ASTPENDING) == 0))
   92                 printf("failed to set signal flags properly for ast()\n");
   93         mtx_unlock_spin(&sched_lock);
   94         PROC_UNLOCK(p);
   95 #endif
   96 
   97 #ifdef KTRACE
   98         KTRUSERRET(td);
   99 #endif
  100 
  101         /*
  102          * If this thread tickled GEOM, we need to wait for the giggling to
  103          * stop before we return to userland
  104          */
  105         if (td->td_pflags & TDP_GEOM)
  106                 g_waitidle();
  107 
  108         /*
  109          * We need to check to see if we have to exit or wait due to a
  110          * single threading requirement or some other STOP condition.
  111          * Don't bother doing all the work if the stop bits are not set
  112          * at this time.. If we miss it, we miss it.. no big deal.
  113          */
  114         if (P_SHOULDSTOP(p)) {
  115                 PROC_LOCK(p);
  116                 thread_suspend_check(0);        /* Can suspend or kill */
  117                 PROC_UNLOCK(p);
  118         }
  119 
  120         /*
  121          * Do special thread processing, e.g. upcall tweaking and such.
  122          */
  123         if (p->p_flag & P_SA)
  124                 thread_userret(td, frame);
  125 
  126         /*
  127          * Charge system time if profiling.
  128          */
  129         if (p->p_flag & P_PROFIL) {
  130                 quad_t ticks;
  131 
  132                 ticks = td->td_sticks - oticks;
  133                 addupc_task(td, TRAPF_PC(frame), (u_int)ticks * psratio);
  134         }
  135 
  136         /*
  137          * Let the scheduler adjust our priority etc.
  138          */
  139         sched_userret(td);
  140         KASSERT(td->td_locks == 0,
  141             ("userret: Returning with %d locks held.", td->td_locks));
  142 }
  143 
  144 /*
  145  * Process an asynchronous software trap.
  146  * This is relatively easy.
  147  * This function will return with preemption disabled.
  148  */
  149 void
  150 ast(struct trapframe *framep)
  151 {
  152         struct thread *td;
  153         struct proc *p;
  154         struct ksegrp *kg;
  155         struct rlimit rlim;
  156         u_int sticks;
  157         int sflag;
  158         int flags;
  159         int sig;
  160 #if defined(DEV_NPX) && !defined(SMP)
  161         int ucode;
  162 #endif
  163 
  164         td = curthread;
  165         p = td->td_proc;
  166         kg = td->td_ksegrp;
  167 
  168         CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
  169             p->p_comm);
  170         KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
  171         WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
  172         mtx_assert(&Giant, MA_NOTOWNED);
  173         mtx_assert(&sched_lock, MA_NOTOWNED);
  174         td->td_frame = framep;
  175         sticks = td->td_sticks;
  176 
  177         if ((p->p_flag & P_SA) && (td->td_mailbox == NULL))
  178                 thread_user_enter(td);
  179 
  180         /*
  181          * This updates the p_sflag's for the checks below in one
  182          * "atomic" operation with turning off the astpending flag.
  183          * If another AST is triggered while we are handling the
  184          * AST's saved in sflag, the astpending flag will be set and
  185          * ast() will be called again.
  186          */
  187         mtx_lock_spin(&sched_lock);
  188         flags = td->td_flags;
  189         sflag = p->p_sflag;
  190         p->p_sflag &= ~(PS_ALRMPEND | PS_PROFPEND | PS_XCPU);
  191 #ifdef MAC
  192         p->p_sflag &= ~PS_MACPEND;
  193 #endif
  194         td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK |
  195             TDF_NEEDRESCHED | TDF_INTERRUPT);
  196         cnt.v_soft++;
  197         mtx_unlock_spin(&sched_lock);
  198 
  199         /*
  200          * XXXKSE While the fact that we owe a user profiling
  201          * tick is stored per KSE in this code, the statistics
  202          * themselves are still stored per process.
  203          * This should probably change, by which I mean that
  204          * possibly the location of both might change.
  205          */
  206         if (td->td_ucred != p->p_ucred) 
  207                 cred_update_thread(td);
  208         if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
  209                 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
  210                 td->td_profil_ticks = 0;
  211                 td->td_pflags &= ~TDP_OWEUPC;
  212         }
  213         if (sflag & PS_ALRMPEND) {
  214                 PROC_LOCK(p);
  215                 psignal(p, SIGVTALRM);
  216                 PROC_UNLOCK(p);
  217         }
  218 #if defined(DEV_NPX) && !defined(SMP)
  219         if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
  220                 atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
  221                     PCB_NPXTRAP);
  222                 ucode = npxtrap();
  223                 if (ucode != -1) {
  224                         trapsignal(td, SIGFPE, ucode);
  225                 }
  226         }
  227 #endif
  228         if (sflag & PS_PROFPEND) {
  229                 PROC_LOCK(p);
  230                 psignal(p, SIGPROF);
  231                 PROC_UNLOCK(p);
  232         }
  233         if (sflag & PS_XCPU) {
  234                 PROC_LOCK(p);
  235                 lim_rlimit(p, RLIMIT_CPU, &rlim);
  236                 mtx_lock_spin(&sched_lock);
  237                 if (p->p_rux.rux_runtime.sec >= rlim.rlim_max) {
  238                         mtx_unlock_spin(&sched_lock);
  239                         killproc(p, "exceeded maximum CPU limit");
  240                 } else {
  241                         if (p->p_cpulimit < rlim.rlim_max)
  242                                 p->p_cpulimit += 5;
  243                         mtx_unlock_spin(&sched_lock);
  244                         psignal(p, SIGXCPU);
  245                 }
  246                 PROC_UNLOCK(p);
  247         }
  248 #ifdef MAC
  249         if (sflag & PS_MACPEND)
  250                 mac_thread_userret(td);
  251 #endif
  252         if (flags & TDF_NEEDRESCHED) {
  253 #ifdef KTRACE
  254                 if (KTRPOINT(td, KTR_CSW))
  255                         ktrcsw(1, 1);
  256 #endif
  257                 mtx_lock_spin(&sched_lock);
  258                 sched_prio(td, kg->kg_user_pri);
  259                 mi_switch(SW_INVOL, NULL);
  260                 mtx_unlock_spin(&sched_lock);
  261 #ifdef KTRACE
  262                 if (KTRPOINT(td, KTR_CSW))
  263                         ktrcsw(0, 1);
  264 #endif
  265         }
  266         if (flags & TDF_NEEDSIGCHK) {
  267                 PROC_LOCK(p);
  268                 mtx_lock(&p->p_sigacts->ps_mtx);
  269                 while ((sig = cursig(td)) != 0)
  270                         postsig(sig);
  271                 mtx_unlock(&p->p_sigacts->ps_mtx);
  272                 PROC_UNLOCK(p);
  273         }
  274 
  275         userret(td, framep, sticks);
  276         mtx_assert(&Giant, MA_NOTOWNED);
  277 }

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