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  * Copyright (c) 2007 The FreeBSD Foundation
    6  *
    7  * This code is derived from software contributed to Berkeley by
    8  * the University of Utah, and William Jolitz.
    9  *
   10  * Portions of this software were developed by A. Joseph Koshy under
   11  * sponsorship from the FreeBSD Foundation and Google, Inc.
   12  *
   13  * Redistribution and use in source and binary forms, with or without
   14  * modification, are permitted provided that the following conditions
   15  * are met:
   16  * 1. Redistributions of source code must retain the above copyright
   17  *    notice, this list of conditions and the following disclaimer.
   18  * 2. Redistributions in binary form must reproduce the above copyright
   19  *    notice, this list of conditions and the following disclaimer in the
   20  *    documentation and/or other materials provided with the distribution.
   21  * 3. All advertising materials mentioning features or use of this software
   22  *    must display the following acknowledgement:
   23  *      This product includes software developed by the University of
   24  *      California, Berkeley and its contributors.
   25  * 4. Neither the name of the University nor the names of its contributors
   26  *    may be used to endorse or promote products derived from this software
   27  *    without specific prior written permission.
   28  *
   29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   39  * SUCH DAMAGE.
   40  *
   41  *      from: @(#)trap.c        7.4 (Berkeley) 5/13/91
   42  */
   43 
   44 #include <sys/cdefs.h>
   45 __FBSDID("$FreeBSD: releng/8.1/sys/kern/subr_trap.c 200725 2009-12-19 11:47:00Z kib $");
   46 
   47 #include "opt_ktrace.h"
   48 #ifdef __i386__
   49 #include "opt_npx.h"
   50 #endif
   51 #include "opt_sched.h"
   52 
   53 #include <sys/param.h>
   54 #include <sys/bus.h>
   55 #include <sys/kernel.h>
   56 #include <sys/lock.h>
   57 #include <sys/mutex.h>
   58 #include <sys/pmckern.h>
   59 #include <sys/proc.h>
   60 #include <sys/ktr.h>
   61 #include <sys/resourcevar.h>
   62 #include <sys/sched.h>
   63 #include <sys/signalvar.h>
   64 #include <sys/systm.h>
   65 #include <sys/vmmeter.h>
   66 #ifdef KTRACE
   67 #include <sys/uio.h>
   68 #include <sys/ktrace.h>
   69 #endif
   70 
   71 #include <machine/cpu.h>
   72 #include <machine/pcb.h>
   73 
   74 #ifdef XEN
   75 #include <vm/vm.h>
   76 #include <vm/vm_param.h>
   77 #include <vm/pmap.h>
   78 #endif
   79 
   80 #include <security/mac/mac_framework.h>
   81 
   82 /*
   83  * Define the code needed before returning to user mode, for trap and
   84  * syscall.
   85  */
   86 void
   87 userret(struct thread *td, struct trapframe *frame)
   88 {
   89         struct proc *p = td->td_proc;
   90 
   91         CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
   92             td->td_name);
   93 #if 0
   94 #ifdef DIAGNOSTIC
   95         /* Check that we called signotify() enough. */
   96         PROC_LOCK(p);
   97         thread_lock(td);
   98         if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
   99             (td->td_flags & TDF_ASTPENDING) == 0))
  100                 printf("failed to set signal flags properly for ast()\n");
  101         thread_unlock(td);
  102         PROC_UNLOCK(p);
  103 #endif
  104 #endif
  105 #ifdef KTRACE
  106         KTRUSERRET(td);
  107 #endif
  108         /*
  109          * If this thread tickled GEOM, we need to wait for the giggling to
  110          * stop before we return to userland
  111          */
  112         if (td->td_pflags & TDP_GEOM)
  113                 g_waitidle();
  114 
  115         /*
  116          * Charge system time if profiling.
  117          */
  118         if (p->p_flag & P_PROFIL) {
  119                 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
  120         }
  121         /*
  122          * Let the scheduler adjust our priority etc.
  123          */
  124         sched_userret(td);
  125         KASSERT(td->td_locks == 0,
  126             ("userret: Returning with %d locks held.", td->td_locks));
  127 #ifdef XEN
  128         PT_UPDATES_FLUSH();
  129 #endif
  130 }
  131 
  132 /*
  133  * Process an asynchronous software trap.
  134  * This is relatively easy.
  135  * This function will return with preemption disabled.
  136  */
  137 void
  138 ast(struct trapframe *framep)
  139 {
  140         struct thread *td;
  141         struct proc *p;
  142         int flags;
  143         int sig;
  144 #if defined(DEV_NPX) && !defined(SMP)
  145         int ucode;
  146         ksiginfo_t ksi;
  147 #endif
  148 
  149         td = curthread;
  150         p = td->td_proc;
  151 
  152         CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
  153             p->p_comm);
  154         KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
  155         WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
  156         mtx_assert(&Giant, MA_NOTOWNED);
  157         THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
  158         td->td_frame = framep;
  159         td->td_pticks = 0;
  160 
  161         /*
  162          * This updates the td_flag's for the checks below in one
  163          * "atomic" operation with turning off the astpending flag.
  164          * If another AST is triggered while we are handling the
  165          * AST's saved in flags, the astpending flag will be set and
  166          * ast() will be called again.
  167          */
  168         thread_lock(td);
  169         flags = td->td_flags;
  170         td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
  171             TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
  172         thread_unlock(td);
  173         PCPU_INC(cnt.v_trap);
  174 
  175         if (td->td_ucred != p->p_ucred) 
  176                 cred_update_thread(td);
  177         if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
  178                 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
  179                 td->td_profil_ticks = 0;
  180                 td->td_pflags &= ~TDP_OWEUPC;
  181         }
  182         if (flags & TDF_ALRMPEND) {
  183                 PROC_LOCK(p);
  184                 psignal(p, SIGVTALRM);
  185                 PROC_UNLOCK(p);
  186         }
  187 #if defined(DEV_NPX) && !defined(SMP)
  188         if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
  189                 atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
  190                     PCB_NPXTRAP);
  191                 ucode = npxtrap();
  192                 if (ucode != -1) {
  193                         ksiginfo_init_trap(&ksi);
  194                         ksi.ksi_signo = SIGFPE;
  195                         ksi.ksi_code = ucode;
  196                         trapsignal(td, &ksi);
  197                 }
  198         }
  199 #endif
  200         if (flags & TDF_PROFPEND) {
  201                 PROC_LOCK(p);
  202                 psignal(p, SIGPROF);
  203                 PROC_UNLOCK(p);
  204         }
  205 #ifdef MAC
  206         if (flags & TDF_MACPEND)
  207                 mac_thread_userret(td);
  208 #endif
  209         if (flags & TDF_NEEDRESCHED) {
  210 #ifdef KTRACE
  211                 if (KTRPOINT(td, KTR_CSW))
  212                         ktrcsw(1, 1);
  213 #endif
  214                 thread_lock(td);
  215                 sched_prio(td, td->td_user_pri);
  216                 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
  217                 thread_unlock(td);
  218 #ifdef KTRACE
  219                 if (KTRPOINT(td, KTR_CSW))
  220                         ktrcsw(0, 1);
  221 #endif
  222         }
  223 
  224         /*
  225          * Check for signals. Unlocked reads of p_pendingcnt or
  226          * p_siglist might cause process-directed signal to be handled
  227          * later.
  228          */
  229         if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
  230             !SIGISEMPTY(p->p_siglist)) {
  231                 PROC_LOCK(p);
  232                 mtx_lock(&p->p_sigacts->ps_mtx);
  233                 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0)
  234                         postsig(sig);
  235                 mtx_unlock(&p->p_sigacts->ps_mtx);
  236                 PROC_UNLOCK(p);
  237         }
  238         /*
  239          * We need to check to see if we have to exit or wait due to a
  240          * single threading requirement or some other STOP condition.
  241          */
  242         if (flags & TDF_NEEDSUSPCHK) {
  243                 PROC_LOCK(p);
  244                 thread_suspend_check(0);
  245                 PROC_UNLOCK(p);
  246         }
  247 
  248         if (td->td_pflags & TDP_OLDMASK) {
  249                 td->td_pflags &= ~TDP_OLDMASK;
  250                 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
  251         }
  252 
  253         userret(td, framep);
  254         mtx_assert(&Giant, MA_NOTOWNED);
  255 }

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

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sys/kern/subr_trap.c