Source: linux-2.6 Version: 2.6.32-41 Severity: important The kernel in squeeze does not allow for repeatable measurements, because the wrong multiplier is used for the time calculation. This is due to it missing patch 157a1a27d5921fc94db8c14e0d01363d13de99b5, which was accepted for v2.6.34-rc6 and Cc'ed to stable. The commit fixing it for some other architectures (0696b711e) was backported into 2.6.32 stable. | [S390] vdso: use ntp adjusted clock multiplier | | 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> I can confirm that the attached backported patch builds and works fine on s390 and it should be placed in bugfix/s390. Kind regards Philipp Kern
From 42801c420e59d52003e5ded9658fe8fa599ecaf0 Mon Sep 17 00:00:00 2001
From: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Date: Thu, 22 Apr 2010 17:17:06 +0200
Subject: [PATCH] [S390] vdso: use ntp adjusted clock multiplier
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>
---
arch/s390/include/asm/vdso.h | 1 +
arch/s390/kernel/asm-offsets.c | 1 +
arch/s390/kernel/time.c | 1 +
arch/s390/kernel/vdso32/clock_gettime.S | 12 ++++++------
arch/s390/kernel/vdso32/gettimeofday.S | 6 +++---
arch/s390/kernel/vdso64/clock_gettime.S | 4 ++--
arch/s390/kernel/vdso64/gettimeofday.S | 2 +-
7 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/arch/s390/include/asm/vdso.h b/arch/s390/include/asm/vdso.h
index 4a76d94..533f357 100644
--- a/arch/s390/include/asm/vdso.h
+++ b/arch/s390/include/asm/vdso.h
@@ -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 {
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 63e4643..7ffc4c0 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -52,6 +52,7 @@ 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,
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 68e1ecf..7ad595a 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -228,6 +228,7 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock,
vdso_data->xtime_clock_nsec = xtime.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;
}
diff --git a/arch/s390/kernel/vdso32/clock_gettime.S b/arch/s390/kernel/vdso32/clock_gettime.S
index 4a98909..9696439 100644
--- a/arch/s390/kernel/vdso32/clock_gettime.S
+++ b/arch/s390/kernel/vdso32/clock_gettime.S
@@ -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 */
diff --git a/arch/s390/kernel/vdso32/gettimeofday.S b/arch/s390/kernel/vdso32/gettimeofday.S
index ad8acfc..2d36331 100644
--- a/arch/s390/kernel/vdso32/gettimeofday.S
+++ b/arch/s390/kernel/vdso32/gettimeofday.S
@@ -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 */
diff --git a/arch/s390/kernel/vdso64/clock_gettime.S b/arch/s390/kernel/vdso64/clock_gettime.S
index 49106c6..f404678 100644
--- a/arch/s390/kernel/vdso64/clock_gettime.S
+++ b/arch/s390/kernel/vdso64/clock_gettime.S
@@ -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)
diff --git a/arch/s390/kernel/vdso64/gettimeofday.S b/arch/s390/kernel/vdso64/gettimeofday.S
index f873e75..36ee674 100644
--- a/arch/s390/kernel/vdso64/gettimeofday.S
+++ b/arch/s390/kernel/vdso64/gettimeofday.S
@@ -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 */
--
1.7.9.5
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