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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: 1ba2d6c0fd ("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>
This commit is contained in:
Heiko Carstens 2021-03-24 20:23:55 +01:00
parent b24bacd67f
commit 5b43bd1845
1 changed files with 8 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
arch/s390/kernel/time.c
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@ -80,10 +80,12 @@ void __init time_early_init(void)
{
struct ptff_qto qto;
struct ptff_qui qui;
int cs;
/* Initialize TOD steering parameters */
tod_steering_end = tod_clock_base.tod;
vdso_data->arch_data.tod_steering_end = tod_steering_end;
for (cs = 0; cs < CS_BASES; cs++)
vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
if (!test_facility(28))
return;
@ -366,6 +368,7 @@ static void clock_sync_global(unsigned long delta)
{
unsigned long now, adj;
struct ptff_qto qto;
int cs;
/* Fixup the monotonic sched clock. */
tod_clock_base.eitod += delta;
@ -381,8 +384,10 @@ static void clock_sync_global(unsigned long delta)
panic("TOD clock sync offset %li is too large to drift\n",
tod_steering_delta);
tod_steering_end = now + (abs(tod_steering_delta) << 15);
vdso_data->arch_data.tod_steering_end = tod_steering_end;
vdso_data->arch_data.tod_steering_delta = tod_steering_delta;
for (cs = 0; cs < CS_BASES; cs++) {
vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
vdso_data[cs].arch_data.tod_steering_delta = tod_steering_delta;
}
/* Update LPAR offset. */
if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)