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@@ -8,25 +8,28 @@
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#include <linux/clocksource.h>
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#include <linux/init.h>
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#include <linux/jiffies.h>
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+#include <linux/ktime.h>
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#include <linux/kernel.h>
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#include <linux/moduleparam.h>
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#include <linux/sched.h>
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#include <linux/syscore_ops.h>
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-#include <linux/timer.h>
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+#include <linux/hrtimer.h>
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#include <linux/sched_clock.h>
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+#include <linux/seqlock.h>
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+#include <linux/bitops.h>
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struct clock_data {
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+ ktime_t wrap_kt;
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u64 epoch_ns;
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- u32 epoch_cyc;
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- u32 epoch_cyc_copy;
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+ u64 epoch_cyc;
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+ seqcount_t seq;
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unsigned long rate;
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u32 mult;
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u32 shift;
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bool suspended;
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};
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-static void sched_clock_poll(unsigned long wrap_ticks);
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-static DEFINE_TIMER(sched_clock_timer, sched_clock_poll, 0, 0);
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+static struct hrtimer sched_clock_timer;
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static int irqtime = -1;
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core_param(irqtime, irqtime, int, 0400);
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@@ -35,42 +38,46 @@ static struct clock_data cd = {
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.mult = NSEC_PER_SEC / HZ,
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};
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-static u32 __read_mostly sched_clock_mask = 0xffffffff;
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+static u64 __read_mostly sched_clock_mask;
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-static u32 notrace jiffy_sched_clock_read(void)
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+static u64 notrace jiffy_sched_clock_read(void)
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{
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- return (u32)(jiffies - INITIAL_JIFFIES);
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+ /*
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+ * We don't need to use get_jiffies_64 on 32-bit arches here
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+ * because we register with BITS_PER_LONG
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+ */
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+ return (u64)(jiffies - INITIAL_JIFFIES);
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}
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-static u32 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read;
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+static u32 __read_mostly (*read_sched_clock_32)(void);
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+
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+static u64 notrace read_sched_clock_32_wrapper(void)
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+{
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+ return read_sched_clock_32();
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+}
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+
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+static u64 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read;
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static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift)
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{
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return (cyc * mult) >> shift;
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}
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-static unsigned long long notrace sched_clock_32(void)
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+unsigned long long notrace sched_clock(void)
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{
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u64 epoch_ns;
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- u32 epoch_cyc;
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- u32 cyc;
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+ u64 epoch_cyc;
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+ u64 cyc;
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+ unsigned long seq;
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if (cd.suspended)
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return cd.epoch_ns;
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- /*
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- * Load the epoch_cyc and epoch_ns atomically. We do this by
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- * ensuring that we always write epoch_cyc, epoch_ns and
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- * epoch_cyc_copy in strict order, and read them in strict order.
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- * If epoch_cyc and epoch_cyc_copy are not equal, then we're in
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- * the middle of an update, and we should repeat the load.
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- */
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do {
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+ seq = read_seqcount_begin(&cd.seq);
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epoch_cyc = cd.epoch_cyc;
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- smp_rmb();
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epoch_ns = cd.epoch_ns;
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- smp_rmb();
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- } while (epoch_cyc != cd.epoch_cyc_copy);
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+ } while (read_seqcount_retry(&cd.seq, seq));
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cyc = read_sched_clock();
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cyc = (cyc - epoch_cyc) & sched_clock_mask;
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@@ -83,49 +90,46 @@ static unsigned long long notrace sched_clock_32(void)
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static void notrace update_sched_clock(void)
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{
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unsigned long flags;
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- u32 cyc;
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+ u64 cyc;
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u64 ns;
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cyc = read_sched_clock();
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ns = cd.epoch_ns +
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cyc_to_ns((cyc - cd.epoch_cyc) & sched_clock_mask,
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cd.mult, cd.shift);
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- /*
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- * Write epoch_cyc and epoch_ns in a way that the update is
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- * detectable in cyc_to_fixed_sched_clock().
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- */
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+
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raw_local_irq_save(flags);
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- cd.epoch_cyc_copy = cyc;
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- smp_wmb();
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+ write_seqcount_begin(&cd.seq);
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cd.epoch_ns = ns;
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- smp_wmb();
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cd.epoch_cyc = cyc;
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+ write_seqcount_end(&cd.seq);
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raw_local_irq_restore(flags);
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}
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-static void sched_clock_poll(unsigned long wrap_ticks)
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+static enum hrtimer_restart sched_clock_poll(struct hrtimer *hrt)
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{
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- mod_timer(&sched_clock_timer, round_jiffies(jiffies + wrap_ticks));
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update_sched_clock();
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+ hrtimer_forward_now(hrt, cd.wrap_kt);
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+ return HRTIMER_RESTART;
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}
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-void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
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+void __init sched_clock_register(u64 (*read)(void), int bits,
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+ unsigned long rate)
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{
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- unsigned long r, w;
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+ unsigned long r;
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u64 res, wrap;
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char r_unit;
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if (cd.rate > rate)
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return;
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- BUG_ON(bits > 32);
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WARN_ON(!irqs_disabled());
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read_sched_clock = read;
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- sched_clock_mask = (1ULL << bits) - 1;
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+ sched_clock_mask = CLOCKSOURCE_MASK(bits);
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cd.rate = rate;
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/* calculate the mult/shift to convert counter ticks to ns. */
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- clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 0);
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+ clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 3600);
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r = rate;
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if (r >= 4000000) {
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@@ -138,20 +142,14 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
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r_unit = ' ';
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/* calculate how many ns until we wrap */
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- wrap = cyc_to_ns((1ULL << bits) - 1, cd.mult, cd.shift);
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- do_div(wrap, NSEC_PER_MSEC);
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- w = wrap;
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+ wrap = clocks_calc_max_nsecs(cd.mult, cd.shift, 0, sched_clock_mask);
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+ cd.wrap_kt = ns_to_ktime(wrap - (wrap >> 3));
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/* calculate the ns resolution of this counter */
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res = cyc_to_ns(1ULL, cd.mult, cd.shift);
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- pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lums\n",
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- bits, r, r_unit, res, w);
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+ pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lluns\n",
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+ bits, r, r_unit, res, wrap);
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- /*
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- * Start the timer to keep sched_clock() properly updated and
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- * sets the initial epoch.
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- */
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- sched_clock_timer.data = msecs_to_jiffies(w - (w / 10));
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update_sched_clock();
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/*
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@@ -166,11 +164,10 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
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pr_debug("Registered %pF as sched_clock source\n", read);
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}
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-unsigned long long __read_mostly (*sched_clock_func)(void) = sched_clock_32;
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-
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-unsigned long long notrace sched_clock(void)
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+void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
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{
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- return sched_clock_func();
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+ read_sched_clock_32 = read;
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+ sched_clock_register(read_sched_clock_32_wrapper, bits, rate);
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}
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void __init sched_clock_postinit(void)
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@@ -180,14 +177,22 @@ void __init sched_clock_postinit(void)
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* make it the final one one.
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*/
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if (read_sched_clock == jiffy_sched_clock_read)
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- setup_sched_clock(jiffy_sched_clock_read, 32, HZ);
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+ sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG, HZ);
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- sched_clock_poll(sched_clock_timer.data);
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+ update_sched_clock();
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+
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+ /*
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+ * Start the timer to keep sched_clock() properly updated and
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+ * sets the initial epoch.
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+ */
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+ hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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+ sched_clock_timer.function = sched_clock_poll;
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+ hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);
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}
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static int sched_clock_suspend(void)
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{
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- sched_clock_poll(sched_clock_timer.data);
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+ sched_clock_poll(&sched_clock_timer);
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cd.suspended = true;
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return 0;
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}
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@@ -195,7 +200,6 @@ static int sched_clock_suspend(void)
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static void sched_clock_resume(void)
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{
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cd.epoch_cyc = read_sched_clock();
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- cd.epoch_cyc_copy = cd.epoch_cyc;
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cd.suspended = false;
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}
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