linux.git/arch/s390/kernel/time.c, branch v6.9

s390/time: make stp_subsys const

2024-02-09T12:58:15+00:00

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 
Suggested-by: Greg Kroah-Hartman 
Signed-off-by: "Ricardo B. Marliere" 
Reviewed-by: Greg Kroah-Hartman 
Link: https://lore.kernel.org/r/20240204-bus_cleanup-s390_time-v1-1-d2120156982a@marliere.net
Signed-off-by: Heiko Carstens

s390/time: improve steering precision

2024-02-09T12:58:14+00:00

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

s390: use control register bit defines

2023-09-19T11:26:57+00:00

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

Reviewed-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

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

2023-09-19T11:26:56+00:00

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 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390: fix various typos

2023-07-03T09:19:42+00:00

Fix various typos found with codespell.

Signed-off-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev

s390/time: Provide sched_clock_noinstr()

2023-06-05T19:11:06+00:00

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) 
Acked-by: Heiko Carstens 
Tested-by: Michael Kelley   # Hyper-V
Link: https://lore.kernel.org/r/20230519102715.570170436@infradead.org

s390/stp: clock_delta should be signed

2022-05-11T12:40:57+00:00

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

s390/stp: fix todoff size

2022-05-11T12:40:57+00:00

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

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

s390/vdso: fix initializing and updating of vdso_data

2021-03-25T20:57:26+00:00

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 
Tested-by: Li Wang 
Fixes: 1ba2d6c0fd4e ("s390/vdso: simplify __arch_get_hw_counter()")
Link: https://lore.kernel.org/linux-s390/YFnxr1ZlMIOIqjfq@osiris
Signed-off-by: Heiko Carstens

s390/vdso: copy tod_steering_delta value to vdso_data page

2021-03-25T20:57:25+00:00

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:  # 5.10
Signed-off-by: Heiko Carstens