s390/time: make stp_subsys const

Now that the driver core can properly handle constant struct bus_type,
move the stp_subsys variable to be a constant structure as well,
placing it into read-only mem

s390/time: make stp_subsys const

Now that the driver core can properly handle constant struct bus_type,
move the stp_subsys variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Ricardo B. Marliere" <ricardo@marliere.net>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240204-bus_cleanup-s390_time-v1-1-d2120156982a@marliere.net
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390/time: improve steering precision

The common timekeeping code steers the clock by adjusting the multiplier
value of the clock. With the current value of 1000 precision is lost
when the clock is

s390/time: improve steering precision

The common timekeeping code steers the clock by adjusting the multiplier
value of the clock. With the current value of 1000 precision is lost
when the clock is steered with a userspace daemon. Increase the multiplier
and the shift values to increase precision.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390: use control register bit defines

Use control register bit defines instead of plain numbers where
possible.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carsten

s390: use control register bit defines

Use control register bit defines instead of plain numbers where
possible.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/ctlreg: add local and system prefix to some functions

Add local and system prefix to some functions to clarify they change
control register contents on either the local CPU or the on all CPUs.

s390/ctlreg: add local and system prefix to some functions

Add local and system prefix to some functions to clarify they change
control register contents on either the local CPU or the on all CPUs.

This results in the following API:

Two defines which load and save multiple control registers.
The defines correlate with the following C prototypes:

void __local_ctl_load(unsigned long *, unsigned int cr_low, unsigned int cr_high);
void __local_ctl_store(unsigned long *, unsigned int cr_low, unsigned int cr_high);

Two functions which locally set or clear one bit for a specified
control register:

void local_ctl_set_bit(unsigned int cr, unsigned int bit);
void local_ctl_clear_bit(unsigned int cr, unsigned int bit);

Two functions which set or clear one bit for a specified control
register on all CPUs:

void system_ctl_set_bit(unsigned int cr, unsigned int bit);
void system_ctl_clear_bit(unsigend int cr, unsigned int bit);

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390: fix various typos

Fix various typos found with codespell.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

s390/time: Provide sched_clock_noinstr()

With the intent to provide local_clock_noinstr(), a variant of
local_clock() that's safe to be called from noinstr code (with the
assumption that any such co

s390/time: Provide sched_clock_noinstr()

With the intent to provide local_clock_noinstr(), a variant of
local_clock() that's safe to be called from noinstr code (with the
assumption that any such code will already be non-preemptible),
prepare for things by providing a noinstr sched_clock_noinstr()
function.

Specifically, preempt_enable_*() calls out to schedule(), which upsets
noinstr validation efforts.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Michael Kelley <mikelley@microsoft.com> # Hyper-V
Link: https://lore.kernel.org/r/20230519102715.570170436@infradead.org

show more ...

s390/stp: clock_delta should be signed

clock_delta is declared as unsigned long in various places. However,
the clock sync delta can be negative. This would add a huge positive
offset in clock_sync_

s390/stp: clock_delta should be signed

clock_delta is declared as unsigned long in various places. However,
the clock sync delta can be negative. This would add a huge positive
offset in clock_sync_global where clock_delta is added to clk.eitod
which is a 72 bit integer. Declare it as signed long to fix this.

Cc: stable@vger.kernel.org
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390/stp: fix todoff size

The size of the TOD offset field in the stp info response is 64 bits.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@de.ibm.com>
Signe

s390/stp: fix todoff size

The size of the TOD offset field in the stp info response is 64 bits.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390/vdso: fix initializing and updating of vdso_data

Li Wang reported that clock_gettime(CLOCK_MONOTONIC_RAW, ...) returns
incorrect values when time is provided via vdso instead of system call:

v

s390/vdso: fix initializing and updating of vdso_data

Li Wang reported that clock_gettime(CLOCK_MONOTONIC_RAW, ...) returns
incorrect values when time is provided via vdso instead of system call:

vdso_ts_nsec = 4484351380985507, vdso_ts.tv_sec = 4484351, vdso_ts.tv_nsec = 380985507
sys_ts_nsec = 1446923235377, sys_ts.tv_sec = 1446, sys_ts.tv_nsec = 923235377

Within the s390 specific vdso function __arch_get_hw_counter() reads
tod clock steering values from the arch_data member of the passed in
vdso_data structure.

Problem is that only for the CS_HRES_COARSE vdso_data arch_data is
initialized and gets updated. The CS_RAW specific vdso_data does not
contain any valid tod_clock_steering information, which explains the
different values.

Fix this by initializing and updating all vdso_datas.

Reported-by: Li Wang <liwang@redhat.com>
Tested-by: Li Wang <liwang@redhat.com>
Fixes: 1ba2d6c0fd4e ("s390/vdso: simplify __arch_get_hw_counter()")
Link: https://lore.kernel.org/linux-s390/YFnxr1ZlMIOIqjfq@osiris
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390/vdso: copy tod_steering_delta value to vdso_data page

When converting the vdso assembler code to C it was forgotten to
actually copy the tod_steering_delta value to vdso_data page.

Which in tu

s390/vdso: copy tod_steering_delta value to vdso_data page

When converting the vdso assembler code to C it was forgotten to
actually copy the tod_steering_delta value to vdso_data page.

Which in turn means that tod clock steering will not work correctly.

Fix this by simply copying the value whenever it is updated.

Fixes: 4bff8cb54502 ("s390: convert to GENERIC_VDSO")
Cc: <stable@vger.kernel.org> # 5.10
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390/time,idle: get rid of unsigned long long

Get rid of unsigned long long, and use unsigned long instead
everywhere. The usage of unsigned long long is a leftover from
31 bit kernel support.

Sign

s390/time,idle: get rid of unsigned long long

Get rid of unsigned long long, and use unsigned long instead
everywhere. The usage of unsigned long long is a leftover from
31 bit kernel support.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390/time: convert tod_clock_base to union

Convert tod_clock_base to union tod_clock. This simplifies quite a bit
of code and also fixes a bug in read_persistent_clock64();

void read_persistent_clo

s390/time: convert tod_clock_base to union

Convert tod_clock_base to union tod_clock. This simplifies quite a bit
of code and also fixes a bug in read_persistent_clock64();

void read_persistent_clock64(struct timespec64 *ts)
{
__u64 delta;

delta = initial_leap_seconds + TOD_UNIX_EPOCH;
get_tod_clock_ext(clk);
*(__u64 *) &clk[1] -= delta;
if (*(__u64 *) &clk[1] > delta)
clk[0]--;
ext_to_timespec64(clk, ts);
}

Assume &clk[1] == 3 and delta == 2; then after the substraction the if
condition becomes true and the epoch part of the clock is decremented
by one because of an assumed overflow, even though there is none.

Fix this by using 128 bit arithmetics and let the compiler do the
right thing:

void read_persistent_clock64(struct timespec64 *ts)
{
union tod_clock clk;
u64 delta;

delta = initial_leap_seconds + TOD_UNIX_EPOCH;
store_tod_clock_ext(&clk);
clk.eitod -= delta;
ext_to_timespec64(&clk, ts);
}

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/stp: let subsys_system_register() sysfs attributes

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

This also ensures

s390/stp: let subsys_system_register() sysfs attributes

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 <jwi@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390/stp: unify stp_work_mutex and clock_sync_mutex

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

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Alexander Eg

s390/stp: unify stp_work_mutex and clock_sync_mutex

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

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

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

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

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

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 <svens@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/stp: add support for leap seconds

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) chang

s390/stp: add support for leap seconds

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 <svens@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/stp: add locking to sysfs functions

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_onl

s390/stp: add locking to sysfs functions

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 <svens@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390: convert to GENERIC_VDSO

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

s390: convert to GENERIC_VDSO

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 <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/time: improve comparison for tod steering

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

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

s390/time: use CLOCKSOURCE_MASK

Make use of CLOCKSOURCE_MASK instead of open-coding it.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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

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

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Heiko Carste

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

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

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

show more ...

s390: convert to msecs_to_jiffies()

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 <sv

s390: convert to msecs_to_jiffies()

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 <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

show more ...

s390/vdso: fix vDSO clock_getres()

clock_getres in the vDSO library has to preserve the same behaviour
of posix_get_hrtimer_res().

In particular, posix_get_hrtimer_res() does:
sec = 0;
ns =

s390/vdso: fix vDSO clock_getres()

clock_getres in the vDSO library has to preserve the same behaviour
of posix_get_hrtimer_res().

In particular, posix_get_hrtimer_res() does:
sec = 0;
ns = hrtimer_resolution;
and hrtimer_resolution depends on the enablement of the high
resolution timers that can happen either at compile or at run time.

Fix the s390 vdso implementation of clock_getres keeping a copy of
hrtimer_resolution in vdso data and using that directly.

Link: https://lkml.kernel.org/r/20200324121027.21665-1-vincenzo.frascino@arm.com
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
[heiko.carstens@de.ibm.com: use llgf for proper zero extension]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/time: remove monotonic_clock()

Remove unused monotonic_clock() function.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

s390/time: Remove read_boot_clock64()

read_boot_clock64() was replaced by read_persistent_wall_and_boot_offset()
so remove it.

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-b

s390/time: Remove read_boot_clock64()

read_boot_clock64() was replaced by read_persistent_wall_and_boot_offset()
so remove it.

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Cc: linux@armlinux.org.uk
Cc: schwidefsky@de.ibm.com
Cc: heiko.carstens@de.ibm.com
Cc: john.stultz@linaro.org
Cc: sboyd@codeaurora.org
Cc: hpa@zytor.com
Cc: douly.fnst@cn.fujitsu.com
Cc: peterz@infradead.org
Cc: prarit@redhat.com
Cc: feng.tang@intel.com
Cc: pmladek@suse.com
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: linux-s390@vger.kernel.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: pbonzini@redhat.com
Link: https://lkml.kernel.org/r/20180719205545.16512-18-pasha.tatashin@oracle.com

show more ...