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: releng/6.0/sys/kern/subr_trap.c 144223 2005-03-28 12:52:46Z jeff $");
   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         /*
   98          * If this thread tickled GEOM, we need to wait for the giggling to
   99          * stop before we return to userland
  100          */
  101         if (td->td_pflags & TDP_GEOM)
  102                 g_waitidle();
  103 
  104         /*
  105          * We need to check to see if we have to exit or wait due to a
  106          * single threading requirement or some other STOP condition.
  107          * Don't bother doing all the work if the stop bits are not set
  108          * at this time.. If we miss it, we miss it.. no big deal.
  109          */
  110         if (P_SHOULDSTOP(p)) {
  111                 PROC_LOCK(p);
  112                 thread_suspend_check(0);        /* Can suspend or kill */
  113                 PROC_UNLOCK(p);
  114         }
  115 
  116         /*
  117          * Do special thread processing, e.g. upcall tweaking and such.
  118          */
  119         if (p->p_flag & P_SA)
  120                 thread_userret(td, frame);
  121 
  122         /*
  123          * Charge system time if profiling.
  124          */
  125         if (p->p_flag & P_PROFIL) {
  126                 quad_t ticks;
  127 
  128                 ticks = td->td_sticks - oticks;
  129                 addupc_task(td, TRAPF_PC(frame), (u_int)ticks * psratio);
  130         }
  131 
  132         /*
  133          * Let the scheduler adjust our priority etc.
  134          */
  135         sched_userret(td);
  136         KASSERT(td->td_locks == 0,
  137             ("userret: Returning with %d locks held.", td->td_locks));
  138 }
  139 
  140 /*
  141  * Process an asynchronous software trap.
  142  * This is relatively easy.
  143  * This function will return with preemption disabled.
  144  */
  145 void
  146 ast(struct trapframe *framep)
  147 {
  148         struct thread *td;
  149         struct proc *p;
  150         struct ksegrp *kg;
  151         struct rlimit rlim;
  152         u_int sticks;
  153         int sflag;
  154         int flags;
  155         int sig;
  156 #if defined(DEV_NPX) && !defined(SMP)
  157         int ucode;
  158 #endif
  159 
  160         td = curthread;
  161         p = td->td_proc;
  162         kg = td->td_ksegrp;
  163 
  164         CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
  165             p->p_comm);
  166         KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
  167         WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
  168         mtx_assert(&Giant, MA_NOTOWNED);
  169         mtx_assert(&sched_lock, MA_NOTOWNED);
  170         td->td_frame = framep;
  171         sticks = td->td_sticks;
  172 
  173         if ((p->p_flag & P_SA) && (td->td_mailbox == NULL))
  174                 thread_user_enter(td);
  175 
  176         /*
  177          * This updates the p_sflag's for the checks below in one
  178          * "atomic" operation with turning off the astpending flag.
  179          * If another AST is triggered while we are handling the
  180          * AST's saved in sflag, the astpending flag will be set and
  181          * ast() will be called again.
  182          */
  183         mtx_lock_spin(&sched_lock);
  184         flags = td->td_flags;
  185         sflag = p->p_sflag;
  186         p->p_sflag &= ~(PS_ALRMPEND | PS_PROFPEND | PS_XCPU);
  187 #ifdef MAC
  188         p->p_sflag &= ~PS_MACPEND;
  189 #endif
  190         td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK |
  191             TDF_NEEDRESCHED | TDF_INTERRUPT);
  192         cnt.v_soft++;
  193         mtx_unlock_spin(&sched_lock);
  194 
  195         /*
  196          * XXXKSE While the fact that we owe a user profiling
  197          * tick is stored per KSE in this code, the statistics
  198          * themselves are still stored per process.
  199          * This should probably change, by which I mean that
  200          * possibly the location of both might change.
  201          */
  202         if (td->td_ucred != p->p_ucred) 
  203                 cred_update_thread(td);
  204         if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
  205                 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
  206                 td->td_profil_ticks = 0;
  207                 td->td_pflags &= ~TDP_OWEUPC;
  208         }
  209         if (sflag & PS_ALRMPEND) {
  210                 PROC_LOCK(p);
  211                 psignal(p, SIGVTALRM);
  212                 PROC_UNLOCK(p);
  213         }
  214 #if defined(DEV_NPX) && !defined(SMP)
  215         if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
  216                 atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
  217                     PCB_NPXTRAP);
  218                 ucode = npxtrap();
  219                 if (ucode != -1) {
  220                         trapsignal(td, SIGFPE, ucode);
  221                 }
  222         }
  223 #endif
  224         if (sflag & PS_PROFPEND) {
  225                 PROC_LOCK(p);
  226                 psignal(p, SIGPROF);
  227                 PROC_UNLOCK(p);
  228         }
  229         if (sflag & PS_XCPU) {
  230                 PROC_LOCK(p);
  231                 lim_rlimit(p, RLIMIT_CPU, &rlim);
  232                 mtx_lock_spin(&sched_lock);
  233                 if (p->p_rux.rux_runtime.sec >= rlim.rlim_max) {
  234                         mtx_unlock_spin(&sched_lock);
  235                         killproc(p, "exceeded maximum CPU limit");
  236                 } else {
  237                         if (p->p_cpulimit < rlim.rlim_max)
  238                                 p->p_cpulimit += 5;
  239                         mtx_unlock_spin(&sched_lock);
  240                         psignal(p, SIGXCPU);
  241                 }
  242                 PROC_UNLOCK(p);
  243         }
  244 #ifdef MAC
  245         if (sflag & PS_MACPEND)
  246                 mac_thread_userret(td);
  247 #endif
  248         if (flags & TDF_NEEDRESCHED) {
  249 #ifdef KTRACE
  250                 if (KTRPOINT(td, KTR_CSW))
  251                         ktrcsw(1, 1);
  252 #endif
  253                 mtx_lock_spin(&sched_lock);
  254                 sched_prio(td, kg->kg_user_pri);
  255                 mi_switch(SW_INVOL, NULL);
  256                 mtx_unlock_spin(&sched_lock);
  257 #ifdef KTRACE
  258                 if (KTRPOINT(td, KTR_CSW))
  259                         ktrcsw(0, 1);
  260 #endif
  261         }
  262         if (flags & TDF_NEEDSIGCHK) {
  263                 PROC_LOCK(p);
  264                 mtx_lock(&p->p_sigacts->ps_mtx);
  265                 while ((sig = cursig(td)) != 0)
  266                         postsig(sig);
  267                 mtx_unlock(&p->p_sigacts->ps_mtx);
  268                 PROC_UNLOCK(p);
  269         }
  270 
  271         userret(td, framep, sticks);
  272         mtx_assert(&Giant, MA_NOTOWNED);
  273 }

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