6b286ee8b5
not blocking the signal, signal is placed on the thread sigqueue. If the selected thread is in kernel executing thr_exit() or sigprocmask() syscalls, then signal might be not delivered to usermode for arbitrary amount of time, and for exiting thread it is lost. Put process-directed signals to the process queue unconditionally, selecting the thread to deliver the signal only by the thread returning to usermode, since only then the thread can handle delivery of signal reliably. For exiting thread or thread that has blocked some signals, check whether the newly blocked signal is queued for the process, and try to find a thread to wakeup for delivery, in reschedule_signal(). For exiting thread, assume that all signals are blocked. Change cursig() and postsig() to look both into the thread and process signal queues. When there is a signal that thread returning to usermode could consume, TDF_NEEDSIGCHK flag is not neccessary set now. Do unlocked read of p_siglist and p_pendingcnt to check for queued signals. Note that thread that has a signal unblocked might get spurious wakeup and EINTR from the interruptible system call now, due to the possibility of being selected by reschedule_signals(), while other thread returned to usermode earlier and removed the signal from process queue. This should not cause compliance issues, since the thread has not blocked a signal and thus should be ready to receive it anyway. Reported by: Justin Teller <justin.teller gmail com> Reviewed by: davidxu, jilles MFC after: 1 month
251 lines
6.8 KiB
C
251 lines
6.8 KiB
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"
|
|
#ifdef __i386__
|
|
#include "opt_npx.h"
|
|
#endif
|
|
#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/resourcevar.h>
|
|
#include <sys/sched.h>
|
|
#include <sys/signalvar.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/vmmeter.h>
|
|
#ifdef KTRACE
|
|
#include <sys/uio.h>
|
|
#include <sys/ktrace.h>
|
|
#endif
|
|
|
|
#include <machine/cpu.h>
|
|
#include <machine/pcb.h>
|
|
|
|
#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);
|
|
#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));
|
|
#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;
|
|
#if defined(DEV_NPX) && !defined(SMP)
|
|
int ucode;
|
|
ksiginfo_t ksi;
|
|
#endif
|
|
|
|
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 defined(DEV_NPX) && !defined(SMP)
|
|
if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
|
|
atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
|
|
PCB_NPXTRAP);
|
|
ucode = npxtrap();
|
|
if (ucode != -1) {
|
|
ksiginfo_init_trap(&ksi);
|
|
ksi.ksi_signo = SIGFPE;
|
|
ksi.ksi_code = ucode;
|
|
trapsignal(td, &ksi);
|
|
}
|
|
}
|
|
#endif
|
|
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);
|
|
#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);
|
|
#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);
|
|
}
|
|
|
|
userret(td, framep);
|
|
mtx_assert(&Giant, MA_NOTOWNED);
|
|
}
|