593efaf9f7
changes in r246417 were incomplete as they did not add explicit calls to sigdeferstop() around all the places that previously passed SBDRY to _sleep(). In addition, nfs_getcacheblk() could trigger a write RPC from getblk() resulting in sigdeferstop() recursing. Rather than manually deferring stop signals in specific places, change the VFS_*() and VOP_*() methods to defer stop signals for filesystems which request this behavior via a new VFCF_SBDRY flag. Note that this has to be a VFC flag rather than a MNTK flag so that it works properly with VFS_MOUNT() when the mount is not yet fully constructed. For now, only the NFS clients are set this new flag in VFS_SET(). A few other related changes: - Add an assertion to ensure that TDF_SBDRY doesn't leak to userland. - When a lookup request uses VOP_READLINK() to follow a symlink, mark the request as being on behalf of the thread performing the lookup (cnp_thread) rather than using a NULL thread pointer. This causes NFS to properly handle signals during this VOP on an interruptible mount. PR: kern/176179 Reported by: Russell Cattelan (sigdeferstop() recursion) Reviewed by: kib MFC after: 1 month
311 lines
8.8 KiB
C
311 lines
8.8 KiB
C
/*-
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* Copyright (C) 1994, David Greenman
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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* Copyright (c) 2007 The FreeBSD Foundation
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*
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* This code is derived from software contributed to Berkeley by
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* the University of Utah, and William Jolitz.
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*
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* Portions of this software were developed by A. Joseph Koshy under
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* sponsorship from the FreeBSD Foundation and Google, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)trap.c 7.4 (Berkeley) 5/13/91
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_hwpmc_hooks.h"
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#include "opt_ktrace.h"
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#include "opt_kdtrace.h"
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#include "opt_sched.h"
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#include <sys/param.h>
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#include <sys/bus.h>
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#include <sys/capability.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/pmckern.h>
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#include <sys/proc.h>
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#include <sys/ktr.h>
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#include <sys/pioctl.h>
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#include <sys/ptrace.h>
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#include <sys/resourcevar.h>
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#include <sys/sched.h>
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#include <sys/signalvar.h>
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#include <sys/syscall.h>
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#include <sys/syscallsubr.h>
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#include <sys/sysent.h>
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#include <sys/systm.h>
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#include <sys/vmmeter.h>
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#ifdef KTRACE
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#include <sys/uio.h>
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#include <sys/ktrace.h>
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#endif
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#include <security/audit/audit.h>
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#include <machine/cpu.h>
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#ifdef VIMAGE
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#include <net/vnet.h>
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#endif
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#ifdef XEN
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/pmap.h>
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#endif
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#ifdef HWPMC_HOOKS
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#include <sys/pmckern.h>
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#endif
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#include <security/mac/mac_framework.h>
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/*
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* Define the code needed before returning to user mode, for trap and
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* syscall.
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*/
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void
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userret(struct thread *td, struct trapframe *frame)
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{
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struct proc *p = td->td_proc;
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#ifdef RACCT
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int sig;
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#endif
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CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
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td->td_name);
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KASSERT((p->p_flag & P_WEXIT) == 0,
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("Exiting process returns to usermode"));
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#if 0
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#ifdef DIAGNOSTIC
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/* Check that we called signotify() enough. */
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PROC_LOCK(p);
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thread_lock(td);
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if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
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(td->td_flags & TDF_ASTPENDING) == 0))
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printf("failed to set signal flags properly for ast()\n");
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thread_unlock(td);
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PROC_UNLOCK(p);
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#endif
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#endif
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#ifdef KTRACE
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KTRUSERRET(td);
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#endif
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/*
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* If this thread tickled GEOM, we need to wait for the giggling to
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* stop before we return to userland
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*/
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if (td->td_pflags & TDP_GEOM)
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g_waitidle();
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/*
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* Charge system time if profiling.
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*/
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if (p->p_flag & P_PROFIL)
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addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
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/*
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* Let the scheduler adjust our priority etc.
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*/
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sched_userret(td);
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#ifdef XEN
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PT_UPDATES_FLUSH();
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#endif
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/*
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* Check for misbehavior.
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*
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* In case there is a callchain tracing ongoing because of
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* hwpmc(4), skip the scheduler pinning check.
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* hwpmc(4) subsystem, infact, will collect callchain informations
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* at ast() checkpoint, which is past userret().
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*/
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WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
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KASSERT(td->td_critnest == 0,
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("userret: Returning in a critical section"));
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KASSERT(td->td_locks == 0,
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("userret: Returning with %d locks held", td->td_locks));
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KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
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("userret: Returning with pagefaults disabled"));
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KASSERT((td->td_pflags & TDP_NOSLEEPING) == 0,
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("userret: Returning with sleep disabled"));
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KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
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("userret: Returning with with pinned thread"));
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KASSERT(td->td_vp_reserv == 0,
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("userret: Returning while holding vnode reservation"));
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KASSERT((td->td_flags & TDF_SBDRY) == 0,
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("userret: Returning with stop signals deferred"));
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#ifdef VIMAGE
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/* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
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VNET_ASSERT(curvnet == NULL,
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("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
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__func__, td, p->p_pid, td->td_name, curvnet,
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(td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
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#endif
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#ifdef RACCT
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PROC_LOCK(p);
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while (p->p_throttled == 1) {
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sig = msleep(p->p_racct, &p->p_mtx, PCATCH | PBDRY, "racct",
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hz);
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if ((sig == EINTR) || (sig == ERESTART))
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break;
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}
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PROC_UNLOCK(p);
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#endif
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}
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/*
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* Process an asynchronous software trap.
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* This is relatively easy.
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* This function will return with preemption disabled.
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*/
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void
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ast(struct trapframe *framep)
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{
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struct thread *td;
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struct proc *p;
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int flags;
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int sig;
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td = curthread;
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p = td->td_proc;
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CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
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p->p_comm);
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KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
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WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
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mtx_assert(&Giant, MA_NOTOWNED);
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THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
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td->td_frame = framep;
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td->td_pticks = 0;
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/*
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* This updates the td_flag's for the checks below in one
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* "atomic" operation with turning off the astpending flag.
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* If another AST is triggered while we are handling the
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* AST's saved in flags, the astpending flag will be set and
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* ast() will be called again.
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*/
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thread_lock(td);
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flags = td->td_flags;
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td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
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TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
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thread_unlock(td);
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PCPU_INC(cnt.v_trap);
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if (td->td_ucred != p->p_ucred)
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cred_update_thread(td);
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if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
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addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
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td->td_profil_ticks = 0;
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td->td_pflags &= ~TDP_OWEUPC;
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}
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#ifdef HWPMC_HOOKS
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/* Handle Software PMC callchain capture. */
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if (PMC_IS_PENDING_CALLCHAIN(td))
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PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
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#endif
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if (flags & TDF_ALRMPEND) {
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PROC_LOCK(p);
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kern_psignal(p, SIGVTALRM);
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PROC_UNLOCK(p);
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}
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if (flags & TDF_PROFPEND) {
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PROC_LOCK(p);
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kern_psignal(p, SIGPROF);
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PROC_UNLOCK(p);
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}
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#ifdef MAC
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if (flags & TDF_MACPEND)
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mac_thread_userret(td);
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#endif
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if (flags & TDF_NEEDRESCHED) {
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 1, __func__);
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#endif
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thread_lock(td);
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sched_prio(td, td->td_user_pri);
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mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
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thread_unlock(td);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 1, __func__);
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#endif
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}
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/*
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* Check for signals. Unlocked reads of p_pendingcnt or
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* p_siglist might cause process-directed signal to be handled
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* later.
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*/
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if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
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!SIGISEMPTY(p->p_siglist)) {
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PROC_LOCK(p);
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mtx_lock(&p->p_sigacts->ps_mtx);
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while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0)
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postsig(sig);
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mtx_unlock(&p->p_sigacts->ps_mtx);
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PROC_UNLOCK(p);
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}
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/*
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* We need to check to see if we have to exit or wait due to a
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* single threading requirement or some other STOP condition.
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*/
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if (flags & TDF_NEEDSUSPCHK) {
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PROC_LOCK(p);
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thread_suspend_check(0);
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PROC_UNLOCK(p);
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}
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if (td->td_pflags & TDP_OLDMASK) {
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td->td_pflags &= ~TDP_OLDMASK;
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kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
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}
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userret(td, framep);
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}
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const char *
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syscallname(struct proc *p, u_int code)
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{
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static const char unknown[] = "unknown";
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struct sysentvec *sv;
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sv = p->p_sysent;
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if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
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return (unknown);
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return (sv->sv_syscallnames[code]);
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}
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