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[S390] vdso: use ntp adjusted clock multiplier

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Commit "timekeeping: Fix clock_gettime vsyscall time warp" (0696b711e)
introduced the new parameter "mult" to update_vsyscall(). This parameter
contains the internal NTP adjusted clock multiplier.

The s390x vdso did not use this adjusted multiplier.  Instead, it used
the constant clock multiplier for gettimeofday() and clock_gettime()
variants.  This may result in observable time warps as explained in
commit 0696b711e.

Make the NTP adjusted clock multiplier available to the s390x vdso
implementation and use it for time calculations.

Cc: <stable@kernel.org>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Hendrik Brueckner 2010-04-22 17:17:06 +02:00 committed by Martin Schwidefsky
parent 8821d24cd2
commit 157a1a27d5
7 changed files with 15 additions and 12 deletions
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1
arch/s390/include/asm/vdso.h
View File

@ -29,6 +29,7 @@ struct vdso_data {
__u32 tz_minuteswest; /* Minutes west of Greenwich 0x30 */
__u32 tz_dsttime; /* Type of dst correction 0x34 */
__u32 ectg_available;
__u32 ntp_mult; /* NTP adjusted multiplier 0x3C */
};
struct vdso_per_cpu_data {

1
arch/s390/kernel/asm-offsets.c
View File

@ -61,6 +61,7 @@ int main(void)
DEFINE(__VDSO_WTOM_NSEC, offsetof(struct vdso_data, wtom_clock_nsec));
DEFINE(__VDSO_TIMEZONE, offsetof(struct vdso_data, tz_minuteswest));
DEFINE(__VDSO_ECTG_OK, offsetof(struct vdso_data, ectg_available));
DEFINE(__VDSO_NTP_MULT, offsetof(struct vdso_data, ntp_mult));
DEFINE(__VDSO_ECTG_BASE, offsetof(struct vdso_per_cpu_data, ectg_timer_base));
DEFINE(__VDSO_ECTG_USER, offsetof(struct vdso_per_cpu_data, ectg_user_time));
/* constants used by the vdso */

1
arch/s390/kernel/time.c
View File

@ -221,6 +221,7 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock,
vdso_data->xtime_clock_nsec = wall_time->tv_nsec;
vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
vdso_data->ntp_mult = mult;
smp_wmb();
++vdso_data->tb_update_count;
}

12
arch/s390/kernel/vdso32/clock_gettime.S
View File

@ -38,13 +38,13 @@ __kernel_clock_gettime:
sl %r1,__VDSO_XTIME_STAMP+4(%r5)
brc 3,2f
ahi %r0,-1
2: mhi %r0,1000 /* cyc2ns(clock,cycle_delta) */
2: ms %r0,__VDSO_NTP_MULT(%r5) /* cyc2ns(clock,cycle_delta) */
lr %r2,%r0
lhi %r0,1000
l %r0,__VDSO_NTP_MULT(%r5)
ltr %r1,%r1
mr %r0,%r0
jnm 3f
ahi %r0,1000
a %r0,__VDSO_NTP_MULT(%r5)
3: alr %r0,%r2
srdl %r0,12
al %r0,__VDSO_XTIME_NSEC(%r5) /* + xtime */
@ -86,13 +86,13 @@ __kernel_clock_gettime:
sl %r1,__VDSO_XTIME_STAMP+4(%r5)
brc 3,12f
ahi %r0,-1
12: mhi %r0,1000 /* cyc2ns(clock,cycle_delta) */
12: ms %r0,__VDSO_NTP_MULT(%r5) /* cyc2ns(clock,cycle_delta) */
lr %r2,%r0
lhi %r0,1000
l %r0,__VDSO_NTP_MULT(%r5)
ltr %r1,%r1
mr %r0,%r0
jnm 13f
ahi %r0,1000
a %r0,__VDSO_NTP_MULT(%r5)
13: alr %r0,%r2
srdl %r0,12
al %r0,__VDSO_XTIME_NSEC(%r5) /* + xtime */

6
arch/s390/kernel/vdso32/gettimeofday.S
View File

@ -35,13 +35,13 @@ __kernel_gettimeofday:
sl %r1,__VDSO_XTIME_STAMP+4(%r5)
brc 3,3f
ahi %r0,-1
3: mhi %r0,1000 /* cyc2ns(clock,cycle_delta) */
3: ms %r0,__VDSO_NTP_MULT(%r5) /* cyc2ns(clock,cycle_delta) */
st %r0,24(%r15)
lhi %r0,1000
l %r0,__VDSO_NTP_MULT(%r5)
ltr %r1,%r1
mr %r0,%r0
jnm 4f
ahi %r0,1000
a %r0,__VDSO_NTP_MULT(%r5)
4: al %r0,24(%r15)
srdl %r0,12
al %r0,__VDSO_XTIME_NSEC(%r5) /* + xtime */

4
arch/s390/kernel/vdso64/clock_gettime.S
View File

@ -36,7 +36,7 @@ __kernel_clock_gettime:
stck 48(%r15) /* Store TOD clock */
lg %r1,48(%r15)
sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
mghi %r1,1000
msgf %r1,__VDSO_NTP_MULT(%r5) /* * NTP adjustment */
srlg %r1,%r1,12 /* cyc2ns(clock,cycle_delta) */
alg %r1,__VDSO_XTIME_NSEC(%r5) /* + xtime */
lg %r0,__VDSO_XTIME_SEC(%r5)
@ -64,7 +64,7 @@ __kernel_clock_gettime:
stck 48(%r15) /* Store TOD clock */
lg %r1,48(%r15)
sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
mghi %r1,1000
msgf %r1,__VDSO_NTP_MULT(%r5) /* * NTP adjustment */
srlg %r1,%r1,12 /* cyc2ns(clock,cycle_delta) */
alg %r1,__VDSO_XTIME_NSEC(%r5) /* + xtime */
lg %r0,__VDSO_XTIME_SEC(%r5)

2
arch/s390/kernel/vdso64/gettimeofday.S
View File

@ -31,7 +31,7 @@ __kernel_gettimeofday:
stck 48(%r15) /* Store TOD clock */
lg %r1,48(%r15)
sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
mghi %r1,1000
msgf %r1,__VDSO_NTP_MULT(%r5) /* * NTP adjustment */
srlg %r1,%r1,12 /* cyc2ns(clock,cycle_delta) */
alg %r1,__VDSO_XTIME_NSEC(%r5) /* + xtime.tv_nsec */
lg %r0,__VDSO_XTIME_SEC(%r5) /* xtime.tv_sec */