armv7 save/resore pmsel

hulk inclusion
category: feature
bugzilla: 12804
CVE: NA

-------------------------------------------------
Signed-off-by: NJulien Thierry <julien.thierry@arm.com>
Signed-off-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm/kernel/perf_event_v7.c

@@ -736,10 +736,22 @@ static inline int armv7_pmnc_counter_has_overflowed(u32 pmnc, int idx)
 	return pmnc & BIT(ARMV7_IDX_TO_COUNTER(idx));
 }
 
-static inline void armv7_pmnc_select_counter(int idx)
+static inline u32 armv7_pmsel_read(void)
+{
+	u32 pmsel;
+
+	asm volatile("mrc p15, 0, %0, c9, c12, 5" : "=&r" (pmsel));
+	return pmsel;
+}
+
+static inline void armv7_pmsel_write(u32 counter)
 {
-	u32 counter = ARMV7_IDX_TO_COUNTER(idx);
 	asm volatile("mcr p15, 0, %0, c9, c12, 5" : : "r" (counter));
+}
+
+static inline void armv7_pmnc_select_counter(int idx)
+{
+	armv7_pmsel_write(ARMV7_IDX_TO_COUNTER(idx));
 	isb();
 }
 
@@ -952,8 +964,11 @@ static irqreturn_t armv7pmu_handle_irq(struct arm_pmu *cpu_pmu)
 	struct perf_sample_data data;
 	struct pmu_hw_events *cpuc = this_cpu_ptr(cpu_pmu->hw_events);
 	struct pt_regs *regs;
+	u32 pmsel;
 	int idx;
 
+	pmsel = armv7_pmsel_read();
+
 	/*
 	 * Get and reset the IRQ flags
 	 */
@@ -1004,6 +1019,8 @@ static irqreturn_t armv7pmu_handle_irq(struct arm_pmu *cpu_pmu)
 	 */
 	irq_work_run();
 
+	armv7_pmsel_write(pmsel);
+
 	return IRQ_HANDLED;
 }