timekeeping: Fix clock_gettime vsyscall time warp

Since commit 0a544198 "timekeeping: Move NTP adjusted clock multiplier
to struct timekeeper" the clock multiplier of vsyscall is updated with
the unmodified clock multiplier of the clock source and not with the
NTP adjusted multiplier of the timekeeper.

This causes user space observerable time warps:
new CLOCK-warp maximum: 120 nsecs,  00000025c337c537 -> 00000025c337c4bf

Add a new argument "mult" to update_vsyscall() and hand in the
timekeeping internal NTP adjusted multiplier.

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Cc: "Zhang Yanmin" <yanmin_zhang@linux.intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Tony Luck <tony.luck@intel.com>
LKML-Reference: <1258436990.17765.83.camel@minggr.sh.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 4990495d753189933bebf64f18d1f52303b6e6cd..a35c661e5e89a544b097f731af1e65486c3077c2 100644 (file)
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -473,7 +473,7 @@ void update_vsyscall_tz(void)
 {
 }
 
-void update_vsyscall(struct timespec *wall, struct clocksource *c)
+void update_vsyscall(struct timespec *wall, struct clocksource *c, u32 mult)
 {
         unsigned long flags;
 
@@ -481,7 +481,7 @@ void update_vsyscall(struct timespec *wall, struct clocksource *c)
 
         /* copy fsyscall clock data */
         fsyscall_gtod_data.clk_mask = c->mask;
-        fsyscall_gtod_data.clk_mult = c->mult;
+        fsyscall_gtod_data.clk_mult = mult;
         fsyscall_gtod_data.clk_shift = c->shift;
         fsyscall_gtod_data.clk_fsys_mmio = c->fsys_mmio;
         fsyscall_gtod_data.clk_cycle_last = c->cycle_last;

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index a136a11c490d0f36a9b32812132e682c38262f8f..39713312fbc734a897d0b91fa9bc34ec2ca7bd22 100644 (file)
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -828,7 +828,8 @@ static cycle_t timebase_read(struct clocksource *cs)
        return (cycle_t)get_tb();
 }
 
-void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
+void update_vsyscall(struct timespec *wall_time, struct clocksource *clock,
+                    u32 mult)
 {
        u64 t2x, stamp_xsec;
 
@@ -841,7 +842,7 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
 
        /* XXX this assumes clock->shift == 22 */
        /* 4611686018 ~= 2^(20+64-22) / 1e9 */
-       t2x = (u64) clock->mult * 4611686018ULL;
+       t2x = (u64) mult * 4611686018ULL;
        stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
        do_div(stamp_xsec, 1000000000);
        stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 34162a0b2caa6483f397306cc3e21a457b83b051..68e1ecf5ebabf657a6c7e053577752dc69d6046b 100644 (file)
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -214,7 +214,8 @@ struct clocksource * __init clocksource_default_clock(void)
        return &clocksource_tod;
 }
 
-void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
+void update_vsyscall(struct timespec *wall_time, struct clocksource *clock,
+                    u32 mult)
 {
        if (clock != &clocksource_tod)
                return;

diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 8cb4974ff5990c19267077d473caeeb504fe5bae..62f39d79b7754557f0725d5b80b958e5d7c245d8 100644 (file)
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -73,7 +73,8 @@ void update_vsyscall_tz(void)
        write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);
 }
 
-void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
+void update_vsyscall(struct timespec *wall_time, struct clocksource *clock,
+                    u32 mult)
 {
        unsigned long flags;
 
@@ -82,7 +83,7 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
        vsyscall_gtod_data.clock.vread = clock->vread;
        vsyscall_gtod_data.clock.cycle_last = clock->cycle_last;
        vsyscall_gtod_data.clock.mask = clock->mask;
-       vsyscall_gtod_data.clock.mult = clock->mult;
+       vsyscall_gtod_data.clock.mult = mult;
        vsyscall_gtod_data.clock.shift = clock->shift;
        vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec;
        vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec;

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 83d2fbd81b93a056ab7a55c1a1323deb744ef75a..95e4995d99879f921b3f287ffae429671f9bba4d 100644 (file)
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -280,10 +280,12 @@ extern struct clocksource * __init __weak clocksource_default_clock(void);
 extern void clocksource_mark_unstable(struct clocksource *cs);
 
 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
-extern void update_vsyscall(struct timespec *ts, struct clocksource *c);
+extern void
+update_vsyscall(struct timespec *ts, struct clocksource *c, u32 mult);
 extern void update_vsyscall_tz(void);
 #else
-static inline void update_vsyscall(struct timespec *ts, struct clocksource *c)
+static inline void
+update_vsyscall(struct timespec *ts, struct clocksource *c, u32 mult)
 {
 }
 

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index c3a4e2907eaaf3ec25941d0cc69b04ac35b8dc40..2a6d3e3e2c3eceedcbcf42c98439acb656e0dede 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -177,7 +177,7 @@ void timekeeping_leap_insert(int leapsecond)
 {
        xtime.tv_sec += leapsecond;
        wall_to_monotonic.tv_sec -= leapsecond;
-       update_vsyscall(&xtime, timekeeper.clock);
+       update_vsyscall(&xtime, timekeeper.clock, timekeeper.mult);
 }
 
 #ifdef CONFIG_GENERIC_TIME
@@ -337,7 +337,7 @@ int do_settimeofday(struct timespec *tv)
        timekeeper.ntp_error = 0;
        ntp_clear();
 
-       update_vsyscall(&xtime, timekeeper.clock);
+       update_vsyscall(&xtime, timekeeper.clock, timekeeper.mult);
 
        write_sequnlock_irqrestore(&xtime_lock, flags);
 
@@ -811,7 +811,7 @@ void update_wall_time(void)
        update_xtime_cache(nsecs);
 
        /* check to see if there is a new clocksource to use */
-       update_vsyscall(&xtime, timekeeper.clock);
+       update_vsyscall(&xtime, timekeeper.clock, timekeeper.mult);
 }
 
 /**