3 files changed, 94 insertions, 66 deletions

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 50a8736757f3..64cf63ca09cc 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -479,6 +479,7 @@ static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }
 static inline void clocksource_resume_watchdog(void) { }
 static inline int __clocksource_watchdog_kthread(void) { return 0; }
 static bool clocksource_is_watchdog(struct clocksource *cs) { return false; }
+void clocksource_mark_unstable(struct clocksource *cs) { }
 
 #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */
 
@@ -537,40 +538,55 @@ static u32 clocksource_max_adjustment(struct clocksource *cs)
 }
 
 /**
- * clocksource_max_deferment - Returns max time the clocksource can be deferred
- * @cs:         Pointer to clocksource
- *
+ * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted
+ * @mult:       cycle to nanosecond multiplier
+ * @shift:      cycle to nanosecond divisor (power of two)
+ * @maxadj:     maximum adjustment value to mult (~11%)
+ * @mask:       bitmask for two's complement subtraction of non 64 bit counters
  */
-static u64 clocksource_max_deferment(struct clocksource *cs)
+u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask)
 {
         u64 max_nsecs, max_cycles;
 
         /*
          * Calculate the maximum number of cycles that we can pass to the
          * cyc2ns function without overflowing a 64-bit signed result. The
-         * maximum number of cycles is equal to ULLONG_MAX/(cs->mult+cs->maxadj)
+         * maximum number of cycles is equal to ULLONG_MAX/(mult+maxadj)
          * which is equivalent to the below.
-         * max_cycles < (2^63)/(cs->mult + cs->maxadj)
-         * max_cycles < 2^(log2((2^63)/(cs->mult + cs->maxadj)))
-         * max_cycles < 2^(log2(2^63) - log2(cs->mult + cs->maxadj))
-         * max_cycles < 2^(63 - log2(cs->mult + cs->maxadj))
-         * max_cycles < 1 << (63 - log2(cs->mult + cs->maxadj))
+         * max_cycles < (2^63)/(mult + maxadj)
+         * max_cycles < 2^(log2((2^63)/(mult + maxadj)))
+         * max_cycles < 2^(log2(2^63) - log2(mult + maxadj))
+         * max_cycles < 2^(63 - log2(mult + maxadj))
+         * max_cycles < 1 << (63 - log2(mult + maxadj))
          * Please note that we add 1 to the result of the log2 to account for
          * any rounding errors, ensure the above inequality is satisfied and
          * no overflow will occur.
          */
-        max_cycles = 1ULL << (63 - (ilog2(cs->mult + cs->maxadj) + 1));
+        max_cycles = 1ULL << (63 - (ilog2(mult + maxadj) + 1));
 
         /*
          * The actual maximum number of cycles we can defer the clocksource is
-         * determined by the minimum of max_cycles and cs->mask.
+         * determined by the minimum of max_cycles and mask.
          * Note: Here we subtract the maxadj to make sure we don't sleep for
          * too long if there's a large negative adjustment.
          */
-        max_cycles = min_t(u64, max_cycles, (u64) cs->mask);
-        max_nsecs = clocksource_cyc2ns(max_cycles, cs->mult - cs->maxadj,
-                                        cs->shift);
+        max_cycles = min(max_cycles, mask);
+        max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift);
+
+        return max_nsecs;
+}
+
+/**
+ * clocksource_max_deferment - Returns max time the clocksource can be deferred
+ * @cs:         Pointer to clocksource
+ *
+ */
+static u64 clocksource_max_deferment(struct clocksource *cs)
+{
+        u64 max_nsecs;
 
+        max_nsecs = clocks_calc_max_nsecs(cs->mult, cs->shift, cs->maxadj,
+                                          cs->mask);
         /*
          * To ensure that the clocksource does not wrap whilst we are idle,
          * limit the time the clocksource can be deferred by 12.5%. Please
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index bb2215174f05..af8d1d4f3d55 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -475,6 +475,7 @@ static void sync_cmos_clock(struct work_struct *work)
          * called as close as possible to 500 ms before the new second starts.
          * This code is run on a timer.  If the clock is set, that timer
          * may not expire at the correct time.  Thus, we adjust...
+         * We want the clock to be within a couple of ticks from the target.
          */
         if (!ntp_synced()) {
                 /*
@@ -485,7 +486,7 @@ static void sync_cmos_clock(struct work_struct *work)
         }
 
         getnstimeofday(&now);
-        if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) {
+        if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec * 5) {
                 struct timespec adjust = now;
 
                 fail = -ENODEV;
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index 0b479a6a22bb..f388baeaf2b6 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -8,25 +8,28 @@
 #include <linux/clocksource.h>
 #include <linux/init.h>
 #include <linux/jiffies.h>
+#include <linux/ktime.h>
 #include <linux/kernel.h>
 #include <linux/moduleparam.h>
 #include <linux/sched.h>
 #include <linux/syscore_ops.h>
-#include <linux/timer.h>
+#include <linux/hrtimer.h>
 #include <linux/sched_clock.h>
+#include <linux/seqlock.h>
+#include <linux/bitops.h>
 
 struct clock_data {
+        ktime_t wrap_kt;
         u64 epoch_ns;
-        u32 epoch_cyc;
-        u32 epoch_cyc_copy;
+        u64 epoch_cyc;
+        seqcount_t seq;
         unsigned long rate;
         u32 mult;
         u32 shift;
         bool suspended;
 };
 
-static void sched_clock_poll(unsigned long wrap_ticks);
-static DEFINE_TIMER(sched_clock_timer, sched_clock_poll, 0, 0);
+static struct hrtimer sched_clock_timer;
 static int irqtime = -1;
 
 core_param(irqtime, irqtime, int, 0400);
@@ -35,14 +38,25 @@ static struct clock_data cd = {
         .mult   = NSEC_PER_SEC / HZ,
 };
 
-static u32 __read_mostly sched_clock_mask = 0xffffffff;
+static u64 __read_mostly sched_clock_mask;
 
-static u32 notrace jiffy_sched_clock_read(void)
+static u64 notrace jiffy_sched_clock_read(void)
 {
-        return (u32)(jiffies - INITIAL_JIFFIES);
+        /*
+         * We don't need to use get_jiffies_64 on 32-bit arches here
+         * because we register with BITS_PER_LONG
+         */
+        return (u64)(jiffies - INITIAL_JIFFIES);
 }
 
-static u32 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read;
+static u32 __read_mostly (*read_sched_clock_32)(void);
+
+static u64 notrace read_sched_clock_32_wrapper(void)
+{
+        return read_sched_clock_32();
+}
+
+static u64 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read;
 
 static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift)
 {
@@ -52,25 +66,18 @@ static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift)
 static unsigned long long notrace sched_clock_32(void)
 {
         u64 epoch_ns;
-        u32 epoch_cyc;
-        u32 cyc;
+        u64 epoch_cyc;
+        u64 cyc;
+        unsigned long seq;
 
         if (cd.suspended)
                 return cd.epoch_ns;
 
-        /*
-         * Load the epoch_cyc and epoch_ns atomically.  We do this by
-         * ensuring that we always write epoch_cyc, epoch_ns and
-         * epoch_cyc_copy in strict order, and read them in strict order.
-         * If epoch_cyc and epoch_cyc_copy are not equal, then we're in
-         * the middle of an update, and we should repeat the load.
-         */
         do {
+                seq = read_seqcount_begin(&cd.seq);
                 epoch_cyc = cd.epoch_cyc;
-                smp_rmb();
                 epoch_ns = cd.epoch_ns;
-                smp_rmb();
-        } while (epoch_cyc != cd.epoch_cyc_copy);
+        } while (read_seqcount_retry(&cd.seq, seq));
 
         cyc = read_sched_clock();
         cyc = (cyc - epoch_cyc) & sched_clock_mask;
@@ -83,49 +90,46 @@ static unsigned long long notrace sched_clock_32(void)
 static void notrace update_sched_clock(void)
 {
         unsigned long flags;
-        u32 cyc;
+        u64 cyc;
         u64 ns;
 
         cyc = read_sched_clock();
         ns = cd.epoch_ns +
                 cyc_to_ns((cyc - cd.epoch_cyc) & sched_clock_mask,
                           cd.mult, cd.shift);
-        /*
-         * Write epoch_cyc and epoch_ns in a way that the update is
-         * detectable in cyc_to_fixed_sched_clock().
-         */
+
         raw_local_irq_save(flags);
-        cd.epoch_cyc_copy = cyc;
-        smp_wmb();
+        write_seqcount_begin(&cd.seq);
         cd.epoch_ns = ns;
-        smp_wmb();
         cd.epoch_cyc = cyc;
+        write_seqcount_end(&cd.seq);
         raw_local_irq_restore(flags);
 }
 
-static void sched_clock_poll(unsigned long wrap_ticks)
+static enum hrtimer_restart sched_clock_poll(struct hrtimer *hrt)
 {
-        mod_timer(&sched_clock_timer, round_jiffies(jiffies + wrap_ticks));
         update_sched_clock();
+        hrtimer_forward_now(hrt, cd.wrap_kt);
+        return HRTIMER_RESTART;
 }
 
-void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
+void __init sched_clock_register(u64 (*read)(void), int bits,
+                                 unsigned long rate)
 {
-        unsigned long r, w;
+        unsigned long r;
         u64 res, wrap;
         char r_unit;
 
         if (cd.rate > rate)
                 return;
 
-        BUG_ON(bits > 32);
         WARN_ON(!irqs_disabled());
         read_sched_clock = read;
-        sched_clock_mask = (1ULL << bits) - 1;
+        sched_clock_mask = CLOCKSOURCE_MASK(bits);
         cd.rate = rate;
 
         /* calculate the mult/shift to convert counter ticks to ns. */
-        clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 0);
+        clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 3600);
 
         r = rate;
         if (r >= 4000000) {
@@ -138,20 +142,14 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
                 r_unit = ' ';
 
         /* calculate how many ns until we wrap */
-        wrap = cyc_to_ns((1ULL << bits) - 1, cd.mult, cd.shift);
-        do_div(wrap, NSEC_PER_MSEC);
-        w = wrap;
+        wrap = clocks_calc_max_nsecs(cd.mult, cd.shift, 0, sched_clock_mask);
+        cd.wrap_kt = ns_to_ktime(wrap - (wrap >> 3));
 
         /* calculate the ns resolution of this counter */
         res = cyc_to_ns(1ULL, cd.mult, cd.shift);
-        pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lums\n",
-                bits, r, r_unit, res, w);
+        pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lluns\n",
+                bits, r, r_unit, res, wrap);
 
-        /*
-         * Start the timer to keep sched_clock() properly updated and
-         * sets the initial epoch.
-         */
-        sched_clock_timer.data = msecs_to_jiffies(w - (w / 10));
         update_sched_clock();
 
         /*
@@ -166,6 +164,12 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
         pr_debug("Registered %pF as sched_clock source\n", read);
 }
 
+void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
+{
+        read_sched_clock_32 = read;
+        sched_clock_register(read_sched_clock_32_wrapper, bits, rate);
+}
+
 unsigned long long __read_mostly (*sched_clock_func)(void) = sched_clock_32;
 
 unsigned long long notrace sched_clock(void)
@@ -180,14 +184,22 @@ void __init sched_clock_postinit(void)
          * make it the final one one.
          */
         if (read_sched_clock == jiffy_sched_clock_read)
-                setup_sched_clock(jiffy_sched_clock_read, 32, HZ);
+                sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG, HZ);
 
-        sched_clock_poll(sched_clock_timer.data);
+        update_sched_clock();
+
+        /*
+         * Start the timer to keep sched_clock() properly updated and
+         * sets the initial epoch.
+         */
+        hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+        sched_clock_timer.function = sched_clock_poll;
+        hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);
 }
 
 static int sched_clock_suspend(void)
 {
-        sched_clock_poll(sched_clock_timer.data);
+        sched_clock_poll(&sched_clock_timer);
         cd.suspended = true;
         return 0;
 }
@@ -195,7 +207,6 @@ static int sched_clock_suspend(void)
 static void sched_clock_resume(void)
 {
         cd.epoch_cyc = read_sched_clock();
-        cd.epoch_cyc_copy = cd.epoch_cyc;
         cd.suspended = false;
 }