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/7.4/sys/kern/subr_trap.c 172207 2007-09-17 05:31:39Z jeff $");
   42 
   43 #include "opt_ktrace.h"
   44 #include "opt_mac.h"
   45 #ifdef __i386__
   46 #include "opt_npx.h"
   47 #endif
   48 #include "opt_sched.h"
   49 
   50 #include <sys/param.h>
   51 #include <sys/bus.h>
   52 #include <sys/kernel.h>
   53 #include <sys/lock.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 #include <security/mac/mac_framework.h>
   71 
   72 /*
   73  * Define the code needed before returning to user mode, for trap and
   74  * syscall.
   75  */
   76 void
   77 userret(struct thread *td, struct trapframe *frame)
   78 {
   79         struct proc *p = td->td_proc;
   80 
   81         CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
   82             p->p_comm);
   83 #ifdef DIAGNOSTIC
   84         /* Check that we called signotify() enough. */
   85         PROC_LOCK(p);
   86         thread_lock(td);
   87         if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
   88             (td->td_flags & TDF_ASTPENDING) == 0))
   89                 printf("failed to set signal flags properly for ast()\n");
   90         thread_unlock(td);
   91         PROC_UNLOCK(p);
   92 #endif
   93 
   94 #ifdef KTRACE
   95         KTRUSERRET(td);
   96 #endif
   97 
   98         /*
   99          * If this thread tickled GEOM, we need to wait for the giggling to
  100          * stop before we return to userland
  101          */
  102         if (td->td_pflags & TDP_GEOM)
  103                 g_waitidle();
  104 
  105         /*
  106          * We need to check to see if we have to exit or wait due to a
  107          * single threading requirement or some other STOP condition.
  108          * Don't bother doing all the work if the stop bits are not set
  109          * at this time.. If we miss it, we miss it.. no big deal.
  110          */
  111         if (P_SHOULDSTOP(p)) {
  112                 PROC_LOCK(p);
  113                 thread_suspend_check(0);        /* Can suspend or kill */
  114                 PROC_UNLOCK(p);
  115         }
  116 
  117 #ifdef KSE
  118         /*
  119          * Do special thread processing, e.g. upcall tweaking and such.
  120          */
  121         if (p->p_flag & P_SA)
  122                 thread_userret(td, frame);
  123 #endif
  124 
  125         /*
  126          * Charge system time if profiling.
  127          */
  128         if (p->p_flag & P_PROFIL) {
  129 
  130                 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
  131         }
  132 
  133         /*
  134          * Let the scheduler adjust our priority etc.
  135          */
  136         sched_userret(td);
  137         KASSERT(td->td_locks == 0,
  138             ("userret: Returning with %d locks held.", td->td_locks));
  139 }
  140 
  141 /*
  142  * Process an asynchronous software trap.
  143  * This is relatively easy.
  144  * This function will return with preemption disabled.
  145  */
  146 void
  147 ast(struct trapframe *framep)
  148 {
  149         struct thread *td;
  150         struct proc *p;
  151         int flags;
  152         int sig;
  153 #if defined(DEV_NPX) && !defined(SMP)
  154         int ucode;
  155         ksiginfo_t ksi;
  156 #endif
  157 
  158         td = curthread;
  159         p = td->td_proc;
  160 
  161         CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
  162             p->p_comm);
  163         KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
  164         WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
  165         mtx_assert(&Giant, MA_NOTOWNED);
  166         THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
  167         td->td_frame = framep;
  168         td->td_pticks = 0;
  169 
  170 #ifdef KSE
  171         if ((p->p_flag & P_SA) && (td->td_mailbox == NULL))
  172                 thread_user_enter(td);
  173 #endif
  174 
  175         /*
  176          * This updates the td_flag's for the checks below in one
  177          * "atomic" operation with turning off the astpending flag.
  178          * If another AST is triggered while we are handling the
  179          * AST's saved in flags, the astpending flag will be set and
  180          * ast() will be called again.
  181          */
  182         thread_lock(td);
  183         flags = td->td_flags;
  184         td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK |
  185             TDF_NEEDRESCHED | TDF_INTERRUPT | TDF_ALRMPEND | TDF_PROFPEND |
  186             TDF_MACPEND);
  187         thread_unlock(td);
  188         PCPU_INC(cnt.v_trap);
  189 
  190         /*
  191          * XXXKSE While the fact that we owe a user profiling
  192          * tick is stored per thread in this code, the statistics
  193          * themselves are still stored per process.
  194          * This should probably change, by which I mean that
  195          * possibly the location of both might change.
  196          */
  197         if (td->td_ucred != p->p_ucred) 
  198                 cred_update_thread(td);
  199         if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
  200                 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
  201                 td->td_profil_ticks = 0;
  202                 td->td_pflags &= ~TDP_OWEUPC;
  203         }
  204         if (flags & TDF_ALRMPEND) {
  205                 PROC_LOCK(p);
  206                 psignal(p, SIGVTALRM);
  207                 PROC_UNLOCK(p);
  208         }
  209 #if defined(DEV_NPX) && !defined(SMP)
  210         if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
  211                 atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
  212                     PCB_NPXTRAP);
  213                 ucode = npxtrap();
  214                 if (ucode != -1) {
  215                         ksiginfo_init_trap(&ksi);
  216                         ksi.ksi_signo = SIGFPE;
  217                         ksi.ksi_code = ucode;
  218                         trapsignal(td, &ksi);
  219                 }
  220         }
  221 #endif
  222         if (flags & TDF_PROFPEND) {
  223                 PROC_LOCK(p);
  224                 psignal(p, SIGPROF);
  225                 PROC_UNLOCK(p);
  226         }
  227 #ifdef MAC
  228         if (flags & TDF_MACPEND)
  229                 mac_thread_userret(td);
  230 #endif
  231         if (flags & TDF_NEEDRESCHED) {
  232 #ifdef KTRACE
  233                 if (KTRPOINT(td, KTR_CSW))
  234                         ktrcsw(1, 1);
  235 #endif
  236                 thread_lock(td);
  237                 sched_prio(td, td->td_user_pri);
  238                 SCHED_STAT_INC(switch_needresched);
  239                 mi_switch(SW_INVOL, NULL);
  240                 thread_unlock(td);
  241 #ifdef KTRACE
  242                 if (KTRPOINT(td, KTR_CSW))
  243                         ktrcsw(0, 1);
  244 #endif
  245         }
  246         if (flags & TDF_NEEDSIGCHK) {
  247                 PROC_LOCK(p);
  248                 mtx_lock(&p->p_sigacts->ps_mtx);
  249                 while ((sig = cursig(td)) != 0)
  250                         postsig(sig);
  251                 mtx_unlock(&p->p_sigacts->ps_mtx);
  252                 PROC_UNLOCK(p);
  253         }
  254 
  255         userret(td, framep);
  256         mtx_assert(&Giant, MA_NOTOWNED);
  257 }

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