1 files changed, 53 insertions, 4 deletions

diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 03ebecf048c0..a489f31fe147 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -64,6 +64,9 @@ static struct bp_cpuinfo *get_bp_info(int cpu, enum bp_type_idx type)
 	return per_cpu_ptr(bp_cpuinfo + type, cpu);
 }
 
+/* Number of pinned CPU breakpoints globally. */
+static struct bp_slots_histogram cpu_pinned[TYPE_MAX];
+
 /* Keep track of the breakpoints attached to tasks */
 static struct rhltable task_bps_ht;
 static const struct rhashtable_params task_bps_ht_params = {
@@ -194,6 +197,10 @@ static __init int init_breakpoint_slots(void)
 				goto err;
 		}
 	}
+	for (i = 0; i < TYPE_MAX; i++) {
+		if (!bp_slots_histogram_alloc(&cpu_pinned[i], i))
+			goto err;
+	}
 
 	return 0;
 err:
@@ -203,6 +210,8 @@ err:
 		if (err_cpu == cpu)
 			break;
 	}
+	for (i = 0; i < TYPE_MAX; i++)
+		bp_slots_histogram_free(&cpu_pinned[i]);
 
 	return -ENOMEM;
 }
@@ -270,6 +279,9 @@ static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
 /*
  * Count the number of breakpoints of the same type and same task.
  * The given event must be not on the list.
+ *
+ * If @cpu is -1, but the result of task_bp_pinned() is not CPU-independent,
+ * returns a negative value.
  */
 static int task_bp_pinned(int cpu, struct perf_event *bp, enum bp_type_idx type)
 {
@@ -288,9 +300,18 @@ static int task_bp_pinned(int cpu, struct perf_event *bp, enum bp_type_idx type)
 		goto out;
 
 	rhl_for_each_entry_rcu(iter, pos, head, hw.bp_list) {
-		if (find_slot_idx(iter->attr.bp_type) == type &&
-		    (iter->cpu < 0 || cpu == iter->cpu))
-			count += hw_breakpoint_weight(iter);
+		if (find_slot_idx(iter->attr.bp_type) != type)
+			continue;
+
+		if (iter->cpu >= 0) {
+			if (cpu == -1) {
+				count = -1;
+				goto out;
+			} else if (cpu != iter->cpu)
+				continue;
+		}
+
+		count += hw_breakpoint_weight(iter);
 	}
 
 out:
@@ -316,6 +337,19 @@ max_bp_pinned_slots(struct perf_event *bp, enum bp_type_idx type)
 	int pinned_slots = 0;
 	int cpu;
 
+	if (bp->hw.target && bp->cpu < 0) {
+		int max_pinned = task_bp_pinned(-1, bp, type);
+
+		if (max_pinned >= 0) {
+			/*
+			 * Fast path: task_bp_pinned() is CPU-independent and
+			 * returns the same value for any CPU.
+			 */
+			max_pinned += bp_slots_histogram_max(&cpu_pinned[type], type);
+			return max_pinned;
+		}
+	}
+
 	for_each_cpu(cpu, cpumask) {
 		struct bp_cpuinfo *info = get_bp_info(cpu, type);
 		int nr;
@@ -366,8 +400,11 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
 
 	/* Pinned counter cpu profiling */
 	if (!bp->hw.target) {
+		struct bp_cpuinfo *info = get_bp_info(bp->cpu, type);
+
 		lockdep_assert_held_write(&bp_cpuinfo_sem);
-		get_bp_info(bp->cpu, type)->cpu_pinned += weight;
+		bp_slots_histogram_add(&cpu_pinned[type], info->cpu_pinned, weight);
+		info->cpu_pinned += weight;
 		return 0;
 	}
 
@@ -804,6 +841,18 @@ bool hw_breakpoint_is_used(void)
 		}
 	}
 
+	for (int type = 0; type < TYPE_MAX; ++type) {
+		for (int slot = 0; slot < hw_breakpoint_slots_cached(type); ++slot) {
+			/*
+			 * Warn, because if there are CPU pinned counters,
+			 * should never get here; bp_cpuinfo::cpu_pinned should
+			 * be consistent with the global cpu_pinned histogram.
+			 */
+			if (WARN_ON(atomic_read(&cpu_pinned[type].count[slot])))
+				return true;
+		}
+	}
+
 	return false;
 }