perf: RISC-V: throttle perf events

Call perf_sample_event_took() to report time spent in overflow
interrupts. Perf core uses these measurements to throttle
perf events properly.
Signed-off-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20220830155306.301714-4-geomatsi@gmail.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

drivers/perf/riscv_pmu_sbi.c

@@ -18,6 +18,7 @@
 #include <linux/of_irq.h>
 #include <linux/of.h>
 #include <linux/cpu_pm.h>
+#include <linux/sched/clock.h>
 
 #include <asm/sbi.h>
 #include <asm/hwcap.h>
@@ -570,6 +571,7 @@ static irqreturn_t pmu_sbi_ovf_handler(int irq, void *dev)
 	unsigned long overflow;
 	unsigned long overflowed_ctrs = 0;
 	struct cpu_hw_events *cpu_hw_evt = dev;
+	u64 start_clock = sched_clock();
 
 	if (WARN_ON_ONCE(!cpu_hw_evt))
 		return IRQ_NONE;
@@ -638,7 +640,9 @@ static irqreturn_t pmu_sbi_ovf_handler(int irq, void *dev)
 			perf_event_overflow(event, &data, regs);
 		}
 	}
+
 	pmu_sbi_start_overflow_mask(pmu, overflowed_ctrs);
+	perf_sample_event_took(sched_clock() - start_clock);
 
 	return IRQ_HANDLED;
 }