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/10.4/sys/kern/subr_trap.c 303607 2016-08-01 06:35:35Z kib $");
   46 
   47 #include "opt_hwpmc_hooks.h"
   48 #include "opt_ktrace.h"
   49 #include "opt_kdtrace.h"
   50 #include "opt_sched.h"
   51 
   52 #include <sys/param.h>
   53 #include <sys/bus.h>
   54 #include <sys/capsicum.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/pioctl.h>
   62 #include <sys/ptrace.h>
   63 #include <sys/racct.h>
   64 #include <sys/resourcevar.h>
   65 #include <sys/sched.h>
   66 #include <sys/signalvar.h>
   67 #include <sys/syscall.h>
   68 #include <sys/syscallsubr.h>
   69 #include <sys/sysent.h>
   70 #include <sys/systm.h>
   71 #include <sys/vmmeter.h>
   72 #ifdef KTRACE
   73 #include <sys/uio.h>
   74 #include <sys/ktrace.h>
   75 #endif
   76 #include <security/audit/audit.h>
   77 
   78 #include <machine/cpu.h>
   79 
   80 #ifdef VIMAGE
   81 #include <net/vnet.h>
   82 #endif
   83 
   84 #ifdef XEN
   85 #include <vm/vm.h>
   86 #include <vm/vm_param.h>
   87 #include <vm/pmap.h>
   88 #endif
   89 
   90 #ifdef  HWPMC_HOOKS
   91 #include <sys/pmckern.h>
   92 #endif
   93 
   94 #include <security/mac/mac_framework.h>
   95 
   96 void (*softdep_ast_cleanup)(void);
   97 
   98 /*
   99  * Define the code needed before returning to user mode, for trap and
  100  * syscall.
  101  */
  102 void
  103 userret(struct thread *td, struct trapframe *frame)
  104 {
  105         struct proc *p = td->td_proc;
  106 
  107         CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
  108             td->td_name);
  109         KASSERT((p->p_flag & P_WEXIT) == 0,
  110             ("Exiting process returns to usermode"));
  111 #ifdef DIAGNOSTIC
  112         /*
  113          * Check that we called signotify() enough.  For
  114          * multi-threaded processes, where signal distribution might
  115          * change due to other threads changing sigmask, the check is
  116          * racy and cannot be performed reliably.
  117          * If current process is vfork child, indicated by P_PPWAIT, then
  118          * issignal() ignores stops, so we block the check to avoid
  119          * classifying pending signals.
  120          */
  121         if (p->p_numthreads == 1) {
  122                 PROC_LOCK(p);
  123                 thread_lock(td);
  124                 if ((p->p_flag & P_PPWAIT) == 0) {
  125                         KASSERT(!SIGPENDING(td) || (td->td_flags &
  126                             (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
  127                             (TDF_NEEDSIGCHK | TDF_ASTPENDING),
  128                             ("failed to set signal flags for ast p %p "
  129                             "td %p fl %x", p, td, td->td_flags));
  130                 }
  131                 thread_unlock(td);
  132                 PROC_UNLOCK(p);
  133         }
  134 #endif
  135 #ifdef KTRACE
  136         KTRUSERRET(td);
  137 #endif
  138         if (softdep_ast_cleanup != NULL)
  139                 softdep_ast_cleanup();
  140 
  141         /*
  142          * If this thread tickled GEOM, we need to wait for the giggling to
  143          * stop before we return to userland
  144          */
  145         if (td->td_pflags & TDP_GEOM)
  146                 g_waitidle();
  147 
  148         /*
  149          * Charge system time if profiling.
  150          */
  151         if (p->p_flag & P_PROFIL)
  152                 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
  153         /*
  154          * Let the scheduler adjust our priority etc.
  155          */
  156         sched_userret(td);
  157 #ifdef XEN
  158         PT_UPDATES_FLUSH();
  159 #endif
  160 
  161         /*
  162          * Check for misbehavior.
  163          *
  164          * In case there is a callchain tracing ongoing because of
  165          * hwpmc(4), skip the scheduler pinning check.
  166          * hwpmc(4) subsystem, infact, will collect callchain informations
  167          * at ast() checkpoint, which is past userret().
  168          */
  169         WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
  170         KASSERT(td->td_critnest == 0,
  171             ("userret: Returning in a critical section"));
  172         KASSERT(td->td_locks == 0,
  173             ("userret: Returning with %d locks held", td->td_locks));
  174         KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
  175             ("userret: Returning with pagefaults disabled"));
  176         KASSERT(td->td_no_sleeping == 0,
  177             ("userret: Returning with sleep disabled"));
  178         KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
  179             ("userret: Returning with with pinned thread"));
  180         KASSERT(td->td_vp_reserv == 0,
  181             ("userret: Returning while holding vnode reservation"));
  182         KASSERT((td->td_flags & TDF_SBDRY) == 0,
  183             ("userret: Returning with stop signals deferred"));
  184         KASSERT(td->td_su == NULL,
  185             ("userret: Returning with SU cleanup request not handled"));
  186 #ifdef VIMAGE
  187         /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
  188         VNET_ASSERT(curvnet == NULL,
  189             ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
  190             __func__, td, p->p_pid, td->td_name, curvnet,
  191             (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
  192 #endif
  193 #ifdef RACCT
  194         if (racct_enable) {
  195                 PROC_LOCK(p);
  196                 while (p->p_throttled == 1)
  197                         msleep(p->p_racct, &p->p_mtx, 0, "racct", 0);
  198                 PROC_UNLOCK(p);
  199         }
  200 #endif
  201 }
  202 
  203 /*
  204  * Process an asynchronous software trap.
  205  * This is relatively easy.
  206  * This function will return with preemption disabled.
  207  */
  208 void
  209 ast(struct trapframe *framep)
  210 {
  211         struct thread *td;
  212         struct proc *p;
  213         int flags;
  214         int sig;
  215 
  216         td = curthread;
  217         p = td->td_proc;
  218 
  219         CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
  220             p->p_comm);
  221         KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
  222         WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
  223         mtx_assert(&Giant, MA_NOTOWNED);
  224         THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
  225         td->td_frame = framep;
  226         td->td_pticks = 0;
  227 
  228         /*
  229          * This updates the td_flag's for the checks below in one
  230          * "atomic" operation with turning off the astpending flag.
  231          * If another AST is triggered while we are handling the
  232          * AST's saved in flags, the astpending flag will be set and
  233          * ast() will be called again.
  234          */
  235         thread_lock(td);
  236         flags = td->td_flags;
  237         td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
  238             TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
  239         thread_unlock(td);
  240         PCPU_INC(cnt.v_trap);
  241 
  242         if (td->td_ucred != p->p_ucred) 
  243                 cred_update_thread(td);
  244         if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
  245                 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
  246                 td->td_profil_ticks = 0;
  247                 td->td_pflags &= ~TDP_OWEUPC;
  248         }
  249 #ifdef HWPMC_HOOKS
  250         /* Handle Software PMC callchain capture. */
  251         if (PMC_IS_PENDING_CALLCHAIN(td))
  252                 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
  253 #endif
  254         if (flags & TDF_ALRMPEND) {
  255                 PROC_LOCK(p);
  256                 kern_psignal(p, SIGVTALRM);
  257                 PROC_UNLOCK(p);
  258         }
  259         if (flags & TDF_PROFPEND) {
  260                 PROC_LOCK(p);
  261                 kern_psignal(p, SIGPROF);
  262                 PROC_UNLOCK(p);
  263         }
  264 #ifdef MAC
  265         if (flags & TDF_MACPEND)
  266                 mac_thread_userret(td);
  267 #endif
  268         if (flags & TDF_NEEDRESCHED) {
  269 #ifdef KTRACE
  270                 if (KTRPOINT(td, KTR_CSW))
  271                         ktrcsw(1, 1, __func__);
  272 #endif
  273                 thread_lock(td);
  274                 sched_prio(td, td->td_user_pri);
  275                 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
  276                 thread_unlock(td);
  277 #ifdef KTRACE
  278                 if (KTRPOINT(td, KTR_CSW))
  279                         ktrcsw(0, 1, __func__);
  280 #endif
  281         }
  282 
  283 #ifdef DIAGNOSTIC
  284         if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) {
  285                 PROC_LOCK(p);
  286                 thread_lock(td);
  287                 /*
  288                  * Note that TDF_NEEDSIGCHK should be re-read from
  289                  * td_flags, since signal might have been delivered
  290                  * after we cleared td_flags above.  This is one of
  291                  * the reason for looping check for AST condition.
  292                  * See comment in userret() about P_PPWAIT.
  293                  */
  294                 if ((p->p_flag & P_PPWAIT) == 0) {
  295                         KASSERT(!SIGPENDING(td) || (td->td_flags &
  296                             (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
  297                             (TDF_NEEDSIGCHK | TDF_ASTPENDING),
  298                             ("failed2 to set signal flags for ast p %p td %p "
  299                             "fl %x %x", p, td, flags, td->td_flags));
  300                 }
  301                 thread_unlock(td);
  302                 PROC_UNLOCK(p);
  303         }
  304 #endif
  305 
  306         /*
  307          * Check for signals. Unlocked reads of p_pendingcnt or
  308          * p_siglist might cause process-directed signal to be handled
  309          * later.
  310          */
  311         if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
  312             !SIGISEMPTY(p->p_siglist)) {
  313                 PROC_LOCK(p);
  314                 mtx_lock(&p->p_sigacts->ps_mtx);
  315                 while ((sig = cursig(td)) != 0)
  316                         postsig(sig);
  317                 mtx_unlock(&p->p_sigacts->ps_mtx);
  318                 PROC_UNLOCK(p);
  319         }
  320         /*
  321          * We need to check to see if we have to exit or wait due to a
  322          * single threading requirement or some other STOP condition.
  323          */
  324         if (flags & TDF_NEEDSUSPCHK) {
  325                 PROC_LOCK(p);
  326                 thread_suspend_check(0);
  327                 PROC_UNLOCK(p);
  328         }
  329 
  330         if (td->td_pflags & TDP_OLDMASK) {
  331                 td->td_pflags &= ~TDP_OLDMASK;
  332                 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
  333         }
  334 
  335         userret(td, framep);
  336 }
  337 
  338 const char *
  339 syscallname(struct proc *p, u_int code)
  340 {
  341         static const char unknown[] = "unknown";
  342         struct sysentvec *sv;
  343 
  344         sv = p->p_sysent;
  345         if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
  346                 return (unknown);
  347         return (sv->sv_syscallnames[code]);
  348 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_trap.c

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