diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h
index 71d99b83cdb9..0bda22c094a6 100644
--- a/arch/arm/include/asm/pmu.h
+++ b/arch/arm/include/asm/pmu.h
@@ -55,16 +55,6 @@ reserve_pmu(enum arm_pmu_type type);
 extern void
 release_pmu(enum arm_pmu_type type);
 
-/**
- * init_pmu() - Initialise the PMU.
- *
- * Initialise the system ready for PMU enabling. This should typically set the
- * IRQ affinity and nothing else. The users (oprofile/perf events etc) will do
- * the actual hardware initialisation.
- */
-extern int
-init_pmu(enum arm_pmu_type type);
-
 #else /* CONFIG_CPU_HAS_PMU */
 
 #include <linux/err.h>
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 24e2347be6b1..c475379199b1 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -343,8 +343,14 @@ validate_group(struct perf_event *event)
 {
 	struct perf_event *sibling, *leader = event->group_leader;
 	struct pmu_hw_events fake_pmu;
+	DECLARE_BITMAP(fake_used_mask, ARMPMU_MAX_HWEVENTS);
 
-	memset(&fake_pmu, 0, sizeof(fake_pmu));
+	/*
+	 * Initialise the fake PMU. We only need to populate the
+	 * used_mask for the purposes of validation.
+	 */
+	memset(fake_used_mask, 0, sizeof(fake_used_mask));
+	fake_pmu.used_mask = fake_used_mask;
 
 	if (!validate_event(&fake_pmu, leader))
 		return -ENOSPC;
@@ -396,6 +402,9 @@ armpmu_reserve_hardware(struct arm_pmu *armpmu)
 	int i, err, irq, irqs;
 	struct platform_device *pmu_device = armpmu->plat_device;
 
+	if (!pmu_device)
+		return -ENODEV;
+
 	err = reserve_pmu(armpmu->type);
 	if (err) {
 		pr_warning("unable to reserve pmu\n");
diff --git a/arch/arm/kernel/pmu.c b/arch/arm/kernel/pmu.c
index 2c3407ee8576..2334bf8a650a 100644
--- a/arch/arm/kernel/pmu.c
+++ b/arch/arm/kernel/pmu.c
@@ -33,3 +33,4 @@ release_pmu(enum arm_pmu_type type)
 {
 	clear_bit_unlock(type, pmu_lock);
 }
+EXPORT_SYMBOL_GPL(release_pmu);