linux-stable.git/kernel/time, branch linux-5.0.y

timekeeping: Force upper bound for setting CLOCK_REALTIME

2019-05-31T13:45:15+00:00

[ Upstream commit 7a8e61f8478639072d402a26789055a4a4de8f77 ]

Several people reported testing failures after setting CLOCK_REALTIME close
to the limits of the kernel internal representation in nanoseconds,
i.e. year 2262.

The failures are exposed in subsequent operations, i.e. when arming timers
or when the advancing CLOCK_MONOTONIC makes the calculation of
CLOCK_REALTIME overflow into negative space.

Now people start to paper over the underlying problem by clamping
calculations to the valid range, but that's just wrong because such
workarounds will prevent detection of real issues as well.

It is reasonable to force an upper bound for the various methods of setting
CLOCK_REALTIME. Year 2262 is the absolute upper bound. Assume a maximum
uptime of 30 years which is plenty enough even for esoteric embedded
systems. That results in an upper bound of year 2232 for setting the time.

Once that limit is reached in reality this limit is only a small part of
the problem space. But until then this stops people from trying to paper
over the problem at the wrong places.

Reported-by: Xiongfeng Wang 
Reported-by: Hongbo Yao 
Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Cc: Stephen Boyd 
Cc: Miroslav Lichvar 
Cc: Arnd Bergmann 
Cc: Richard Cochran 
Cc: Peter Zijlstra 
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1903231125480.2157@nanos.tec.linutronix.de
Signed-off-by: Sasha Levin

timers/sched_clock: Prevent generic sched_clock wrap caused by tick_freeze()

2019-04-27T07:37:43+00:00

commit 3f2552f7e9c5abef2775c53f7af66532f8bf65bc upstream.

tick_freeze() introduced by suspend-to-idle in commit 124cf9117c5f ("PM /
sleep: Make it possible to quiesce timers during suspend-to-idle") uses
timekeeping_suspend() instead of syscore_suspend() during
suspend-to-idle. As a consequence generic sched_clock will keep going
because sched_clock_suspend() and sched_clock_resume() are not invoked
during suspend-to-idle which can result in a generic sched_clock wrap.

On a ARM system with suspend-to-idle enabled, sched_clock is registered
as "56 bits at 13MHz, resolution 76ns, wraps every 4398046511101ns", which
means the real wrapping duration is 8796093022202ns.

[  134.551779] suspend-to-idle suspend (timekeeping_suspend())
[ 1204.912239] suspend-to-idle resume (timekeeping_resume())
......
[ 1206.912239] suspend-to-idle suspend (timekeeping_suspend())
[ 5880.502807] suspend-to-idle resume (timekeeping_resume())
......
[ 6000.403724] suspend-to-idle suspend (timekeeping_suspend())
[ 8035.753167] suspend-to-idle resume  (timekeeping_resume())
......
[ 8795.786684] (2)[321:charger_thread]......
[ 8795.788387] (2)[321:charger_thread]......
[    0.057226] (0)[0:swapper/0]......
[    0.061447] (2)[0:swapper/2]......

sched_clock was not stopped during suspend-to-idle, and sched_clock_poll
hrtimer was not expired because timekeeping_suspend() was invoked during
suspend-to-idle. It makes sched_clock wrap at kernel time 8796s.

To prevent this, invoke sched_clock_suspend() and sched_clock_resume() in
tick_freeze() together with timekeeping_suspend() and timekeeping_resume().

Fixes: 124cf9117c5f (PM / sleep: Make it possible to quiesce timers during suspend-to-idle)
Signed-off-by: Chang-An Chen 
Signed-off-by: Thomas Gleixner 
Cc: Frederic Weisbecker 
Cc: Matthias Brugger 
Cc: John Stultz 
Cc: Kees Cook 
Cc: Corey Minyard 
Cc: 
Cc: 
Cc: Stanley Chu 
Cc: 
Cc: 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1553828349-8914-1-git-send-email-chang-an.chen@mediatek.com
Signed-off-by: Greg Kroah-Hartman

alarmtimer: Return correct remaining time

2019-04-17T06:39:48+00:00

commit 07d7e12091f4ab869cc6a4bb276399057e73b0b3 upstream.

To calculate a remaining time, it's required to subtract the current time
from the expiration time. In alarm_timer_remaining() the arguments of
ktime_sub are swapped.

Fixes: d653d8457c76 ("alarmtimer: Implement remaining callback")
Signed-off-by: Andrei Vagin 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Mukesh Ojha 
Cc: Stephen Boyd 
Cc: John Stultz 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190408041542.26338-1-avagin@gmail.com
Signed-off-by: Greg Kroah-Hartman

posix-cpu-timers: Unbreak timer rearming

2019-01-15T15:34:37+00:00

The recent commit which prevented a division by 0 issue in the alarm timer
code broke posix CPU timers as an unwanted side effect.

The reason is that the common rearm code checks for timer->it_interval
being 0 now. What went unnoticed is that the posix cpu timer setup does not
initialize timer->it_interval as it stores the interval in CPU timer
specific storage. The reason for the separate storage is historical as the
posix CPU timers always had a 64bit nanoseconds representation internally
while timer->it_interval is type ktime_t which used to be a modified
timespec representation on 32bit machines.

Instead of reverting the offending commit and fixing the alarmtimer issue
in the alarmtimer code, store the interval in timer->it_interval at CPU
timer setup time so the common code check works. This also repairs the
existing inconistency of the posix CPU timer code which kept a single shot
timer armed despite of the interval being 0.

The separate storage can be removed in mainline, but that needs to be a
separate commit as the current one has to be backported to stable kernels.

Fixes: 0e334db6bb4b ("posix-timers: Fix division by zero bug")
Reported-by: H.J. Lu 
Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Cc: Peter Zijlstra 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190111133500.840117406@linutronix.de

Merge tag 'y2038-for-4.21' of ssh://gitolite.kernel.org:/pub/scm/linux/kernel/git/arnd/playground

2018-12-28T20:45:04+00:00

Pull y2038 updates from Arnd Bergmann:
 "More syscalls and cleanups

  This concludes the main part of the system call rework for 64-bit
  time_t, which has spread over most of year 2018, the last six system
  calls being

    - ppoll
    - pselect6
    - io_pgetevents
    - recvmmsg
    - futex
    - rt_sigtimedwait

  As before, nothing changes for 64-bit architectures, while 32-bit
  architectures gain another entry point that differs only in the layout
  of the timespec structure. Hopefully in the next release we can wire
  up all 22 of those system calls on all 32-bit architectures, which
  gives us a baseline version for glibc to start using them.

  This does not include the clock_adjtime, getrusage/waitid, and
  getitimer/setitimer system calls. I still plan to have new versions of
  those as well, but they are not required for correct operation of the
  C library since they can be emulated using the old 32-bit time_t based
  system calls.

  Aside from the system calls, there are also a few cleanups here,
  removing old kernel internal interfaces that have become unused after
  all references got removed. The arch/sh cleanups are part of this,
  there were posted several times over the past year without a reaction
  from the maintainers, while the corresponding changes made it into all
  other architectures"

* tag 'y2038-for-4.21' of ssh://gitolite.kernel.org:/pub/scm/linux/kernel/git/arnd/playground:
  timekeeping: remove obsolete time accessors
  vfs: replace current_kernel_time64 with ktime equivalent
  timekeeping: remove timespec_add/timespec_del
  timekeeping: remove unused {read,update}_persistent_clock
  sh: remove board_time_init() callback
  sh: remove unused rtc_sh_get/set_time infrastructure
  sh: sh03: rtc: push down rtc class ops into driver
  sh: dreamcast: rtc: push down rtc class ops into driver
  y2038: signal: Add compat_sys_rt_sigtimedwait_time64
  y2038: signal: Add sys_rt_sigtimedwait_time32
  y2038: socket: Add compat_sys_recvmmsg_time64
  y2038: futex: Add support for __kernel_timespec
  y2038: futex: Move compat implementation into futex.c
  io_pgetevents: use __kernel_timespec
  pselect6: use __kernel_timespec
  ppoll: use __kernel_timespec
  signal: Add restore_user_sigmask()
  signal: Add set_user_sigmask()

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-12-25T23:44:08+00:00

Pull timer updates from Thomas Gleixner:
 "The timer department delivers the following christmas presents:

  Core code:

   - Use proper seqcount initializer to make lockdep happy

   - SPDX annotations and cleanup of license boilerplates

   - Use DEFINE_SHOW_ATTRIBUTE() instead of open coding it

   - Minor cleanups

  Driver code:

   - Add the sched_clock for the arc timer (Alexey Brodkin)

   - Change the file timer names for riscv, rockchip, tegra20, sun4i and
     meson6 (Daniel Lezcano)

   - Add the DT bindings for r8a7796, r8a77470 and r8a774a1 (Biju Das)

   - Remove the early platform driver registration for timer-ti-dm
     (Bartosz Golaszewski)

   - Provide the sched_clock for the riscv timer (Anup Patel)

   - Add support for ARM64 for the imx-gpt and convert the imx-tpm to
     the timer-of API (Anson Huang)

   - Remove useless irq protection for the imx-gpt (Clément Péron)

   - Remove a duplicate function name for the vt8500 (Dan Carpenter)

   - Remove obsolete inclusion of  for the tegra20 (Geert
     Uytterhoeven)

   - Demote the prcmu and the custom sched_clock for the dbx500 and the
     ux500 (Linus Walleij)

   - Add a new timer clock for the RDA8810PL (Manivannan Sadhasivam)

   - Rename the macro to stick to the register name and add the delay
     timer (Martin Blumenstingl)

   - Switch the bcm2835 to the SPDX identifier (Stefan Wahren)

   - Fix the interrupt register access on the fttmr010 (Tao Ren)

   - Add missing of_node_put in the initialization path on the
     integrator-ap (Yangtao Li)"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
  dt-bindings: timer: Document RDA8810PL SoC timer
  clocksource/drivers/rda: Add clock driver for RDA8810PL SoC
  clocksource/drivers/meson6: Change name meson6_timer timer-meson6
  clocksource/drivers/sun4i: Change name sun4i_timer to timer-sun4i
  clocksource/drivers/tegra20: Change name tegra20_timer to timer-tegra20
  clocksource/drivers/rockchip: Change name rockchip_timer to timer-rockchip
  clocksource/drivers/riscv: Change name riscv_timer to timer-riscv
  clocksource/drivers/riscv_timer: Provide the sched_clock
  clocksource/drivers/timer-imx-tpm: Specify clock name for timer-of
  clocksource/drivers/fttmr010: Fix invalid interrupt register access
  clocksource/drivers/integrator-ap: Add missing of_node_put()
  clocksource/drivers/bcm2835: Switch to SPDX identifier
  dt-bindings: timer: renesas, cmt: Document r8a774a1 CMT support
  clocksource/drivers/timer-imx-tpm: Convert the driver to timer-of
  clocksource/drivers/arc_timer: Utilize generic sched_clock
  dt-bindings: timer: renesas, cmt: Document r8a77470 CMT support
  dt-bindings: timer: renesas, cmt: Document r8a7796 CMT support
  clocksource/drivers/imx-gpt: Remove unnecessary irq protection
  clocksource/drivers/imx-gpt: Add support for ARM64
  clocksource/drivers/meson6_timer: Implement the ARM delay timer
  ...

timekeeping: remove timespec_add/timespec_del

2018-12-18T15:13:05+00:00

The last users were removed a while ago since everyone moved to ktime_t,
so we can remove the two unused interfaces for old timespec structures.

With those two gone, set_normalized_timespec() is also unused, so
remove that as well.

Signed-off-by: Arnd Bergmann 
Acked-by: John Stultz

timekeeping: remove unused {read,update}_persistent_clock

2018-12-18T15:13:05+00:00

After arch/sh has removed the last reference to these functions,
we can remove them completely and just rely on the 64-bit time_t
based versions. This cleans up a rather ugly use of __weak
functions.

Signed-off-by: Arnd Bergmann 
Acked-by: John Stultz

ntp: Remove duplicated include

2018-12-18T11:59:33+00:00

Signed-off-by: YueHaibing 
Signed-off-by: Thomas Gleixner 
Cc: 
Cc: 
Link: https://lkml.kernel.org/r/20181209062225.4344-1-yuehaibing@huawei.com

posix-timers: Fix division by zero bug

2018-12-17T16:35:45+00:00

The signal delivery path of posix-timers can try to rearm the timer even if
the interval is zero. That's handled for the common case (hrtimer) but not
for alarm timers. In that case the forwarding function raises a division by
zero exception.

The handling for hrtimer based posix timers is wrong because it marks the
timer as active despite the fact that it is stopped.

Move the check from common_hrtimer_rearm() to posixtimer_rearm() to cure
both issues.

Reported-by: syzbot+9d38bedac9cc77b8ad5e@syzkaller.appspotmail.com
Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: sboyd@kernel.org
Cc: stable@vger.kernel.org
Cc: syzkaller-bugs@googlegroups.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1812171328050.1880@nanos.tec.linutronix.de
Signed-off-by: Ingo Molnar