linux.git/arch/s390/kernel/time.c, branch v5.11

s390/stp: let subsys_system_register() sysfs attributes

2020-11-20T18:19:11+00:00

Instead of creating the sysfs attributes for the stp root_dev by hand,
pass them to subsys_system_register() as parameter.

This also ensures that the attributes are available when the KOBJ_ADD
event is raised.

Signed-off-by: Julian Wiedmann 
Signed-off-by: Heiko Carstens

s390/stp: unify stp_work_mutex and clock_sync_mutex

2020-09-26T13:51:21+00:00

No need to have two mutexes, and while at it rename it to
stp_mutex.

Signed-off-by: Sven Schnelle 
Reviewed-by: Alexander Egorenkov 
Signed-off-by: Vasily Gorbik

s390/stp: add sysfs file to show scheduled leap seconds

2020-09-26T13:51:21+00:00

This patch introduces /sys/devices/system/stp/scheduled_leap_seconds,
which will contain either 0,0 if no leap second is scheduled, or
the UTC timestamp + leap second offset.

Signed-off-by: Sven Schnelle 
Reviewed-by: Alexander Egorenkov 
Signed-off-by: Vasily Gorbik

s390/stp: add support for leap seconds

2020-09-26T13:51:21+00:00

In the current implementation, leap seconds are only synchronized
during the bootup process when the STP clock is synced. If the Leap
second offset (LSO) changes the machine must be rebooted, which is
not desired. This patch adds the required code to handle Leap second
changes during runtime. If the Leap second changes, a Configuration
change machine check is triggered. The STP code than schedules a Leap
second insertion/deletion with do_adjtimex().

Signed-off-by: Sven Schnelle 
Reviewed-by: Alexander Egorenkov 
Signed-off-by: Vasily Gorbik

s390/stp: add locking to sysfs functions

2020-09-26T13:51:20+00:00

The sysfs function might race with stp_work_fn. To prevent that,
add the required locking. Another issue is that the sysfs functions
are checking the stp_online flag, but this flag just holds the user
setting whether STP is enabled. Add a flag to clock_sync_flag whether
stp_info holds valid data and use that instead.

Cc: stable@vger.kernel.org
Signed-off-by: Sven Schnelle 
Reviewed-by: Alexander Egorenkov 
Signed-off-by: Vasily Gorbik

s390: convert to GENERIC_VDSO

2020-08-26T16:47:21+00:00

Convert s390 to generic vDSO. There are a few special things on s390:

- vDSO can be called without a stack frame - glibc did this in the past.
  So we need to allocate a stackframe on our own.

- The former assembly code used stcke to get the TOD clock and applied
  time steering to it. We need to do the same in the new code. This is done
  in the architecture specific __arch_get_hw_counter function. The steering
  information is stored in an architecure specific area in the vDSO data.

- CPUCLOCK_VIRT is now handled with a syscall fallback, which might
  be slower/less accurate than the old implementation.

The getcpu() function stays as an assembly function because there is no
generic implementation and the code is just a few lines.

Performance number from my system do 100 mio gettimeofday() calls:

Plain syscall: 8.6s
Generic VDSO:  1.3s
old ASM VDSO:  1s

So it's a bit slower but still much faster than syscalls.

Signed-off-by: Sven Schnelle 
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/time: improve comparison for tod steering

2020-07-22T15:02:13+00:00

It doesn't make sense to add zero shifted by 15. It's still zero.

Signed-off-by: Heiko Carstens

s390/time: use CLOCKSOURCE_MASK

2020-07-22T15:02:04+00:00

Make use of CLOCKSOURCE_MASK instead of open-coding it.

Signed-off-by: Heiko Carstens

s390/stp: allow group and users to read stp sysfs files

2020-07-01T18:00:43+00:00

There are no secrets in these files, so allow all users
to read it.

Signed-off-by: Sven Schnelle 
Acked-by: Heiko Carstens 
Signed-off-by: Heiko Carstens

s390: convert to msecs_to_jiffies()

2020-06-29T14:31:46+00:00

Instead of using the old 'jiffies + HZ {/,*} something' calculation
use msecs_to_jiffies() as that makes the code more readable.

Signed-off-by: Sven Schnelle 
Reviewed-by: Heiko Carstens 
Signed-off-by: Heiko Carstens