1 files changed, 112 insertions, 44 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 712570dddacd..5056abffef27 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -376,8 +376,11 @@ static void update_perf_cpu_limits(void)
 	u64 tmp = perf_sample_period_ns;
 
 	tmp *= sysctl_perf_cpu_time_max_percent;
-	do_div(tmp, 100);
-	ACCESS_ONCE(perf_sample_allowed_ns) = tmp;
+	tmp = div_u64(tmp, 100);
+	if (!tmp)
+		tmp = 1;
+
+	WRITE_ONCE(perf_sample_allowed_ns, tmp);
 }
 
 static int perf_rotate_context(struct perf_cpu_context *cpuctx);
@@ -409,7 +412,13 @@ int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
 	if (ret || !write)
 		return ret;
 
-	update_perf_cpu_limits();
+	if (sysctl_perf_cpu_time_max_percent == 100) {
+		printk(KERN_WARNING
+		       "perf: Dynamic interrupt throttling disabled, can hang your system!\n");
+		WRITE_ONCE(perf_sample_allowed_ns, 0);
+	} else {
+		update_perf_cpu_limits();
+	}
 
 	return 0;
 }
@@ -423,62 +432,68 @@ int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
 #define NR_ACCUMULATED_SAMPLES 128
 static DEFINE_PER_CPU(u64, running_sample_length);
 
+static u64 __report_avg;
+static u64 __report_allowed;
+
 static void perf_duration_warn(struct irq_work *w)
 {
-	u64 allowed_ns = ACCESS_ONCE(perf_sample_allowed_ns);
-	u64 avg_local_sample_len;
-	u64 local_samples_len;
-
-	local_samples_len = __this_cpu_read(running_sample_length);
-	avg_local_sample_len = local_samples_len/NR_ACCUMULATED_SAMPLES;
-
 	printk_ratelimited(KERN_WARNING
-			"perf interrupt took too long (%lld > %lld), lowering "
-			"kernel.perf_event_max_sample_rate to %d\n",
-			avg_local_sample_len, allowed_ns >> 1,
-			sysctl_perf_event_sample_rate);
+		"perf: interrupt took too long (%lld > %lld), lowering "
+		"kernel.perf_event_max_sample_rate to %d\n",
+		__report_avg, __report_allowed,
+		sysctl_perf_event_sample_rate);
 }
 
 static DEFINE_IRQ_WORK(perf_duration_work, perf_duration_warn);
 
 void perf_sample_event_took(u64 sample_len_ns)
 {
-	u64 allowed_ns = ACCESS_ONCE(perf_sample_allowed_ns);
-	u64 avg_local_sample_len;
-	u64 local_samples_len;
+	u64 max_len = READ_ONCE(perf_sample_allowed_ns);
+	u64 running_len;
+	u64 avg_len;
+	u32 max;
 
-	if (allowed_ns == 0)
+	if (max_len == 0)
 		return;
 
-	/* decay the counter by 1 average sample */
-	local_samples_len = __this_cpu_read(running_sample_length);
-	local_samples_len -= local_samples_len/NR_ACCUMULATED_SAMPLES;
-	local_samples_len += sample_len_ns;
-	__this_cpu_write(running_sample_length, local_samples_len);
+	/* Decay the counter by 1 average sample. */
+	running_len = __this_cpu_read(running_sample_length);
+	running_len -= running_len/NR_ACCUMULATED_SAMPLES;
+	running_len += sample_len_ns;
+	__this_cpu_write(running_sample_length, running_len);
 
 	/*
-	 * note: this will be biased artifically low until we have
-	 * seen NR_ACCUMULATED_SAMPLES.  Doing it this way keeps us
+	 * Note: this will be biased artifically low until we have
+	 * seen NR_ACCUMULATED_SAMPLES. Doing it this way keeps us
 	 * from having to maintain a count.
 	 */
-	avg_local_sample_len = local_samples_len/NR_ACCUMULATED_SAMPLES;
-
-	if (avg_local_sample_len <= allowed_ns)
+	avg_len = running_len/NR_ACCUMULATED_SAMPLES;
+	if (avg_len <= max_len)
 		return;
 
-	if (max_samples_per_tick <= 1)
-		return;
+	__report_avg = avg_len;
+	__report_allowed = max_len;
 
-	max_samples_per_tick = DIV_ROUND_UP(max_samples_per_tick, 2);
-	sysctl_perf_event_sample_rate = max_samples_per_tick * HZ;
-	perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
+	/*
+	 * Compute a throttle threshold 25% below the current duration.
+	 */
+	avg_len += avg_len / 4;
+	max = (TICK_NSEC / 100) * sysctl_perf_cpu_time_max_percent;
+	if (avg_len < max)
+		max /= (u32)avg_len;
+	else
+		max = 1;
 
-	update_perf_cpu_limits();
+	WRITE_ONCE(perf_sample_allowed_ns, avg_len);
+	WRITE_ONCE(max_samples_per_tick, max);
+
+	sysctl_perf_event_sample_rate = max * HZ;
+	perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
 
 	if (!irq_work_queue(&perf_duration_work)) {
-		early_printk("perf interrupt took too long (%lld > %lld), lowering "
+		early_printk("perf: interrupt took too long (%lld > %lld), lowering "
 			     "kernel.perf_event_max_sample_rate to %d\n",
-			     avg_local_sample_len, allowed_ns >> 1,
+			     __report_avg, __report_allowed,
 			     sysctl_perf_event_sample_rate);
 	}
 }
@@ -2402,14 +2417,24 @@ static void ctx_sched_out(struct perf_event_context *ctx,
 			cpuctx->task_ctx = NULL;
 	}
 
-	is_active ^= ctx->is_active; /* changed bits */
-
+	/*
+	 * Always update time if it was set; not only when it changes.
+	 * Otherwise we can 'forget' to update time for any but the last
+	 * context we sched out. For example:
+	 *
+	 *   ctx_sched_out(.event_type = EVENT_FLEXIBLE)
+	 *   ctx_sched_out(.event_type = EVENT_PINNED)
+	 *
+	 * would only update time for the pinned events.
+	 */
 	if (is_active & EVENT_TIME) {
 		/* update (and stop) ctx time */
 		update_context_time(ctx);
 		update_cgrp_time_from_cpuctx(cpuctx);
 	}
 
+	is_active ^= ctx->is_active; /* changed bits */
+
 	if (!ctx->nr_active || !(is_active & EVENT_ALL))
 		return;
 
@@ -4210,6 +4235,14 @@ static void __perf_event_period(struct perf_event *event,
 	active = (event->state == PERF_EVENT_STATE_ACTIVE);
 	if (active) {
 		perf_pmu_disable(ctx->pmu);
+		/*
+		 * We could be throttled; unthrottle now to avoid the tick
+		 * trying to unthrottle while we already re-started the event.
+		 */
+		if (event->hw.interrupts == MAX_INTERRUPTS) {
+			event->hw.interrupts = 0;
+			perf_log_throttle(event, 1);
+		}
 		event->pmu->stop(event, PERF_EF_UPDATE);
 	}
 
@@ -6702,12 +6735,13 @@ int perf_swevent_get_recursion_context(void)
 }
 EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
 
-inline void perf_swevent_put_recursion_context(int rctx)
+void perf_swevent_put_recursion_context(int rctx)
 {
 	struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
 
 	put_recursion_context(swhash->recursion, rctx);
 }
+EXPORT_SYMBOL_GPL(perf_swevent_put_recursion_context);
 
 void ___perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
 {
@@ -6964,7 +6998,7 @@ static int perf_tp_event_match(struct perf_event *event,
 	return 1;
 }
 
-void perf_tp_event(u64 addr, u64 count, void *record, int entry_size,
+void perf_tp_event(u16 event_type, u64 count, void *record, int entry_size,
 		   struct pt_regs *regs, struct hlist_head *head, int rctx,
 		   struct task_struct *task)
 {
@@ -6976,9 +7010,11 @@ void perf_tp_event(u64 addr, u64 count, void *record, int entry_size,
 		.data = record,
 	};
 
-	perf_sample_data_init(&data, addr, 0);
+	perf_sample_data_init(&data, 0, 0);
 	data.raw = &raw;
 
+	perf_trace_buf_update(record, event_type);
+
 	hlist_for_each_entry_rcu(event, head, hlist_entry) {
 		if (perf_tp_event_match(event, &data, regs))
 			perf_swevent_event(event, count, &data, regs);
@@ -7081,6 +7117,7 @@ static void perf_event_free_filter(struct perf_event *event)
 
 static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
 {
+	bool is_kprobe, is_tracepoint;
 	struct bpf_prog *prog;
 
 	if (event->attr.type != PERF_TYPE_TRACEPOINT)
@@ -7089,20 +7126,31 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
 	if (event->tp_event->prog)
 		return -EEXIST;
 
-	if (!(event->tp_event->flags & TRACE_EVENT_FL_UKPROBE))
-		/* bpf programs can only be attached to u/kprobes */
+	is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_UKPROBE;
+	is_tracepoint = event->tp_event->flags & TRACE_EVENT_FL_TRACEPOINT;
+	if (!is_kprobe && !is_tracepoint)
+		/* bpf programs can only be attached to u/kprobe or tracepoint */
 		return -EINVAL;
 
 	prog = bpf_prog_get(prog_fd);
 	if (IS_ERR(prog))
 		return PTR_ERR(prog);
 
-	if (prog->type != BPF_PROG_TYPE_KPROBE) {
+	if ((is_kprobe && prog->type != BPF_PROG_TYPE_KPROBE) ||
+	    (is_tracepoint && prog->type != BPF_PROG_TYPE_TRACEPOINT)) {
 		/* valid fd, but invalid bpf program type */
 		bpf_prog_put(prog);
 		return -EINVAL;
 	}
 
+	if (is_tracepoint) {
+		int off = trace_event_get_offsets(event->tp_event);
+
+		if (prog->aux->max_ctx_offset > off) {
+			bpf_prog_put(prog);
+			return -EACCES;
+		}
+	}
 	event->tp_event->prog = prog;
 
 	return 0;
@@ -8509,6 +8557,7 @@ SYSCALL_DEFINE5(perf_event_open,
 					f_flags);
 	if (IS_ERR(event_file)) {
 		err = PTR_ERR(event_file);
+		event_file = NULL;
 		goto err_context;
 	}
 
@@ -9426,10 +9475,29 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
 	switch (action & ~CPU_TASKS_FROZEN) {
 
 	case CPU_UP_PREPARE:
+		/*
+		 * This must be done before the CPU comes alive, because the
+		 * moment we can run tasks we can encounter (software) events.
+		 *
+		 * Specifically, someone can have inherited events on kthreadd
+		 * or a pre-existing worker thread that gets re-bound.
+		 */
 		perf_event_init_cpu(cpu);
 		break;
 
 	case CPU_DOWN_PREPARE:
+		/*
+		 * This must be done before the CPU dies because after that an
+		 * active event might want to IPI the CPU and that'll not work
+		 * so great for dead CPUs.
+		 *
+		 * XXX smp_call_function_single() return -ENXIO without a warn
+		 * so we could possibly deal with this.
+		 *
+		 * This is safe against new events arriving because
+		 * sys_perf_event_open() serializes against hotplug using
+		 * get_online_cpus().
+		 */
 		perf_event_exit_cpu(cpu);
 		break;
 	default: