Commit 5b43bd18 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

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: default avatarLi Wang <liwang@redhat.com>
Tested-by: default avatarLi Wang <liwang@redhat.com>
Fixes: 1ba2d6c0 ("s390/vdso: simplify __arch_get_hw_counter()")
Link: https://lore.kernel.org/linux-s390/YFnxr1ZlMIOIqjfq@osiris


Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent b24bacd6

arch/s390/kernel/time.c

+8 −3
Original line number Diff line number Diff line
@@ -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)