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

     /*-
      * Copyright (C) 1994, David Greenman
      * Copyright (c) 1990, 1993
      *      The Regents of the University of California.  All rights reserved.
      * Copyright (c) 2007 The FreeBSD Foundation
      *
      * This code is derived from software contributed to Berkeley by
      * the University of Utah, and William Jolitz.
      *
     * Portions of this software were developed by A. Joseph Koshy under
     * sponsorship from the FreeBSD Foundation and Google, Inc.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      from: @(#)trap.c        7.4 (Berkeley) 5/13/91
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_ktrace.h"
    #include "opt_kdtrace.h"
    #include "opt_sched.h"
    
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/pmckern.h>
    #include <sys/proc.h>
    #include <sys/ktr.h>
    #include <sys/pioctl.h>
    #include <sys/ptrace.h>
    #include <sys/resourcevar.h>
    #include <sys/sched.h>
    #include <sys/signalvar.h>
    #include <sys/syscall.h>
    #include <sys/syscallsubr.h>
    #include <sys/sysent.h>
    #include <sys/systm.h>
    #include <sys/vmmeter.h>
    #ifdef KTRACE
    #include <sys/uio.h>
    #include <sys/ktrace.h>
    #endif
    #include <security/audit/audit.h>
    
    #include <machine/cpu.h>
    
    #ifdef VIMAGE
    #include <net/vnet.h>
    #endif
    
    #ifdef XEN
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <vm/pmap.h>
    #endif
    
    #include <security/mac/mac_framework.h>
    
    /*
     * Define the code needed before returning to user mode, for trap and
     * syscall.
     */
    void
    userret(struct thread *td, struct trapframe *frame)
    {
            struct proc *p = td->td_proc;
    
            CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
                td->td_name);
           KASSERT((p->p_flag & P_WEXIT) == 0,
               ("Exiting process returns to usermode"));
   #if 0
   #ifdef DIAGNOSTIC
           /* Check that we called signotify() enough. */
           PROC_LOCK(p);
           thread_lock(td);
           if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
               (td->td_flags & TDF_ASTPENDING) == 0))
                   printf("failed to set signal flags properly for ast()\n");
           thread_unlock(td);
           PROC_UNLOCK(p);
   #endif
   #endif
   #ifdef KTRACE
           KTRUSERRET(td);
   #endif
           /*
            * If this thread tickled GEOM, we need to wait for the giggling to
            * stop before we return to userland
            */
           if (td->td_pflags & TDP_GEOM)
                   g_waitidle();
   
           /*
            * Charge system time if profiling.
            */
           if (p->p_flag & P_PROFIL)
                   addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
           /*
            * Let the scheduler adjust our priority etc.
            */
           sched_userret(td);
           KASSERT(td->td_locks == 0,
               ("userret: Returning with %d locks held.", td->td_locks));
           KASSERT(td->td_vp_reserv == 0,
               ("userret: Returning while holding vnode reservation"));
           KASSERT((td->td_flags & TDF_SBDRY) == 0,
               ("userret: Returning with stop signals deferred"));
   #ifdef VIMAGE
           /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
           VNET_ASSERT(curvnet == NULL,
               ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
               __func__, td, p->p_pid, td->td_name, curvnet,
               (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
   #endif
   #ifdef XEN
           PT_UPDATES_FLUSH();
   #endif
   }
   
   /*
    * Process an asynchronous software trap.
    * This is relatively easy.
    * This function will return with preemption disabled.
    */
   void
   ast(struct trapframe *framep)
   {
           struct thread *td;
           struct proc *p;
           int flags;
           int sig;
   
           td = curthread;
           p = td->td_proc;
   
           CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
               p->p_comm);
           KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
           WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
           mtx_assert(&Giant, MA_NOTOWNED);
           THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
           td->td_frame = framep;
           td->td_pticks = 0;
   
           /*
            * This updates the td_flag's for the checks below in one
            * "atomic" operation with turning off the astpending flag.
            * If another AST is triggered while we are handling the
            * AST's saved in flags, the astpending flag will be set and
            * ast() will be called again.
            */
           thread_lock(td);
           flags = td->td_flags;
           td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
               TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
           thread_unlock(td);
           PCPU_INC(cnt.v_trap);
   
           if (td->td_ucred != p->p_ucred) 
                   cred_update_thread(td);
           if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
                   addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
                   td->td_profil_ticks = 0;
                   td->td_pflags &= ~TDP_OWEUPC;
           }
           if (flags & TDF_ALRMPEND) {
                   PROC_LOCK(p);
                   psignal(p, SIGVTALRM);
                   PROC_UNLOCK(p);
           }
           if (flags & TDF_PROFPEND) {
                   PROC_LOCK(p);
                   psignal(p, SIGPROF);
                   PROC_UNLOCK(p);
           }
   #ifdef MAC
           if (flags & TDF_MACPEND)
                   mac_thread_userret(td);
   #endif
           if (flags & TDF_NEEDRESCHED) {
   #ifdef KTRACE
                   if (KTRPOINT(td, KTR_CSW))
                           ktrcsw(1, 1, __func__);
   #endif
                   thread_lock(td);
                   sched_prio(td, td->td_user_pri);
                   mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
                   thread_unlock(td);
   #ifdef KTRACE
                   if (KTRPOINT(td, KTR_CSW))
                           ktrcsw(0, 1, __func__);
   #endif
           }
   
           /*
            * Check for signals. Unlocked reads of p_pendingcnt or
            * p_siglist might cause process-directed signal to be handled
            * later.
            */
           if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
               !SIGISEMPTY(p->p_siglist)) {
                   PROC_LOCK(p);
                   mtx_lock(&p->p_sigacts->ps_mtx);
                   while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0)
                           postsig(sig);
                   mtx_unlock(&p->p_sigacts->ps_mtx);
                   PROC_UNLOCK(p);
           }
           /*
            * We need to check to see if we have to exit or wait due to a
            * single threading requirement or some other STOP condition.
            */
           if (flags & TDF_NEEDSUSPCHK) {
                   PROC_LOCK(p);
                   thread_suspend_check(0);
                   PROC_UNLOCK(p);
           }
   
           if (td->td_pflags & TDP_OLDMASK) {
                   td->td_pflags &= ~TDP_OLDMASK;
                   kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
           }
   
           userret(td, framep);
           mtx_assert(&Giant, MA_NOTOWNED);
   }
   
   const char *
   syscallname(struct proc *p, u_int code)
   {
           static const char unknown[] = "unknown";
           struct sysentvec *sv;
   
           sv = p->p_sysent;
           if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
                   return (unknown);
           return (sv->sv_syscallnames[code]);
   }

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