linux.git/arch/s390/kernel/time.c, branch v5.19

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

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

2021-03-08T09:46:27+00:00

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

s390/time: convert tod_clock_base to union

2021-02-13T16:17:54+00:00

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 
Signed-off-by: Vasily Gorbik

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