perf/core: Mark hrtimers to expire in hard interrupt context

To guarantee that the multiplexing mechanism and the hrtimer driven events
work on PREEMPT_RT enabled kernels it's required that the related hrtimers
expire in hard interrupt context. Mark them so PREEMPT_RT kernels wont
defer them to soft interrupt context.

No functional change.

[ tglx: Split out of larger combo patch. Added changelog ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185753.169509224@linutronix.de

kernel/events/core.c

@@ -1103,7 +1103,7 @@ static void __perf_mux_hrtimer_init(struct perf_cpu_context *cpuctx, int cpu)
 	cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * interval);
 
 	raw_spin_lock_init(&cpuctx->hrtimer_lock);
-	hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
+	hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
 	timer->function = perf_mux_hrtimer_handler;
 }
 
@@ -1121,7 +1121,7 @@ static int perf_mux_hrtimer_restart(struct perf_cpu_context *cpuctx)
 	if (!cpuctx->hrtimer_active) {
 		cpuctx->hrtimer_active = 1;
 		hrtimer_forward_now(timer, cpuctx->hrtimer_interval);
-		hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
+		hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD);
 	}
 	raw_spin_unlock_irqrestore(&cpuctx->hrtimer_lock, flags);
 
@@ -9491,7 +9491,7 @@ static void perf_swevent_start_hrtimer(struct perf_event *event)
 		period = max_t(u64, 10000, hwc->sample_period);
 	}
 	hrtimer_start(&hwc->hrtimer, ns_to_ktime(period),
-		      HRTIMER_MODE_REL_PINNED);
+		      HRTIMER_MODE_REL_PINNED_HARD);
 }
 
 static void perf_swevent_cancel_hrtimer(struct perf_event *event)
@@ -9513,7 +9513,7 @@ static void perf_swevent_init_hrtimer(struct perf_event *event)
 	if (!is_sampling_event(event))
 		return;
 
-	hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
 	hwc->hrtimer.function = perf_swevent_hrtimer;
 
 	/*