1 files changed, 49 insertions, 19 deletions

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 29c6482890c8..846861a20b07 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -75,6 +75,8 @@ static unsigned int freeze_events_kernel = MMCR0_FCS;
 
 #define MMCR0_FCHV		0
 #define MMCR0_PMCjCE		MMCR0_PMCnCE
+#define MMCR0_FC56		0
+#define MMCR0_PMAO		0
 
 #define SPRN_MMCRA		SPRN_MMCR2
 #define MMCRA_SAMPLE_ENABLE	0
@@ -747,7 +749,22 @@ static void power_pmu_read(struct perf_event *event)
 	} while (local64_cmpxchg(&event->hw.prev_count, prev, val) != prev);
 
 	local64_add(delta, &event->count);
-	local64_sub(delta, &event->hw.period_left);
+
+	/*
+	 * A number of places program the PMC with (0x80000000 - period_left).
+	 * We never want period_left to be less than 1 because we will program
+	 * the PMC with a value >= 0x800000000 and an edge detected PMC will
+	 * roll around to 0 before taking an exception. We have seen this
+	 * on POWER8.
+	 *
+	 * To fix this, clamp the minimum value of period_left to 1.
+	 */
+	do {
+		prev = local64_read(&event->hw.period_left);
+		val = prev - delta;
+		if (val < 1)
+			val = 1;
+	} while (local64_cmpxchg(&event->hw.period_left, prev, val) != prev);
 }
 
 /*
@@ -852,7 +869,7 @@ static void write_mmcr0(struct cpu_hw_events *cpuhw, unsigned long mmcr0)
 static void power_pmu_disable(struct pmu *pmu)
 {
 	struct cpu_hw_events *cpuhw;
-	unsigned long flags;
+	unsigned long flags, val;
 
 	if (!ppmu)
 		return;
@@ -860,9 +877,6 @@ static void power_pmu_disable(struct pmu *pmu)
 	cpuhw = &__get_cpu_var(cpu_hw_events);
 
 	if (!cpuhw->disabled) {
-		cpuhw->disabled = 1;
-		cpuhw->n_added = 0;
-
 		/*
 		 * Check if we ever enabled the PMU on this cpu.
 		 */
@@ -872,6 +886,21 @@ static void power_pmu_disable(struct pmu *pmu)
 		}
 
 		/*
+		 * Set the 'freeze counters' bit, clear PMAO/FC56.
+		 */
+		val  = mfspr(SPRN_MMCR0);
+		val |= MMCR0_FC;
+		val &= ~(MMCR0_PMAO | MMCR0_FC56);
+
+		/*
+		 * The barrier is to make sure the mtspr has been
+		 * executed and the PMU has frozen the events etc.
+		 * before we return.
+		 */
+		write_mmcr0(cpuhw, val);
+		mb();
+
+		/*
 		 * Disable instruction sampling if it was enabled
 		 */
 		if (cpuhw->mmcr[2] & MMCRA_SAMPLE_ENABLE) {
@@ -880,14 +909,8 @@ static void power_pmu_disable(struct pmu *pmu)
 			mb();
 		}
 
-		/*
-		 * Set the 'freeze counters' bit.
-		 * The barrier is to make sure the mtspr has been
-		 * executed and the PMU has frozen the events
-		 * before we return.
-		 */
-		write_mmcr0(cpuhw, mfspr(SPRN_MMCR0) | MMCR0_FC);
-		mb();
+		cpuhw->disabled = 1;
+		cpuhw->n_added = 0;
 	}
 	local_irq_restore(flags);
 }
@@ -911,12 +934,18 @@ static void power_pmu_enable(struct pmu *pmu)
 
 	if (!ppmu)
 		return;
+
 	local_irq_save(flags);
+
 	cpuhw = &__get_cpu_var(cpu_hw_events);
-	if (!cpuhw->disabled) {
-		local_irq_restore(flags);
-		return;
+	if (!cpuhw->disabled)
+		goto out;
+
+	if (cpuhw->n_events == 0) {
+		ppc_set_pmu_inuse(0);
+		goto out;
 	}
+
 	cpuhw->disabled = 0;
 
 	/*
@@ -928,8 +957,6 @@ static void power_pmu_enable(struct pmu *pmu)
 	if (!cpuhw->n_added) {
 		mtspr(SPRN_MMCRA, cpuhw->mmcr[2] & ~MMCRA_SAMPLE_ENABLE);
 		mtspr(SPRN_MMCR1, cpuhw->mmcr[1]);
-		if (cpuhw->n_events == 0)
-			ppc_set_pmu_inuse(0);
 		goto out_enable;
 	}
 
@@ -1315,6 +1342,9 @@ static int can_go_on_limited_pmc(struct perf_event *event, u64 ev,
 	if (ppmu->limited_pmc_event(ev))
 		return 1;
 
+	if (ppmu->flags & PPMU_ARCH_207S)
+		mtspr(SPRN_MMCR2, 0);
+
 	/*
 	 * The requested event_id isn't on a limited PMC already;
 	 * see if any alternative code goes on a limited PMC.
@@ -1409,7 +1439,7 @@ static int power_pmu_event_init(struct perf_event *event)
 
 	if (has_branch_stack(event)) {
 	        /* PMU has BHRB enabled */
-		if (!(ppmu->flags & PPMU_BHRB))
+		if (!(ppmu->flags & PPMU_ARCH_207S))
 			return -EOPNOTSUPP;
 	}