ftrace: add self-tests

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 415 insertions, 0 deletions

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
new file mode 100644
index 000000000000..ef4d3cc009f5
--- /dev/null
+++ b/kernel/trace/trace_selftest.c
@@ -0,0 +1,415 @@
+/* Include in trace.c */
+
+#include <linux/kthread.h>
+
+static inline int trace_valid_entry(struct trace_entry *entry)
+{
+	switch (entry->type) {
+	case TRACE_FN:
+	case TRACE_CTX:
+		return 1;
+	}
+	return 0;
+}
+
+static int
+trace_test_buffer_cpu(struct trace_array *tr, struct trace_array_cpu *data)
+{
+	struct page *page;
+	struct trace_entry *entries;
+	int idx = 0;
+	int i;
+
+	page = list_entry(data->trace_pages.next, struct page, lru);
+	entries = page_address(page);
+
+	if (data->trace != entries)
+		goto failed;
+
+	/*
+	 * The starting trace buffer always has valid elements,
+	 * if any element exits.
+	 */
+	entries = data->trace;
+
+	for (i = 0; i < tr->entries; i++) {
+
+		if (i < data->trace_idx &&
+		    !trace_valid_entry(&entries[idx])) {
+			printk(KERN_CONT ".. invalid entry %d ", entries[idx].type);
+			goto failed;
+		}
+
+		idx++;
+		if (idx >= ENTRIES_PER_PAGE) {
+			page = virt_to_page(entries);
+			if (page->lru.next == &data->trace_pages) {
+				if (i != tr->entries - 1) {
+					printk(KERN_CONT ".. entries buffer mismatch");
+					goto failed;
+				}
+			} else {
+				page = list_entry(page->lru.next, struct page, lru);
+				entries = page_address(page);
+			}
+			idx = 0;
+		}
+	}
+
+	page = virt_to_page(entries);
+	if (page->lru.next != &data->trace_pages) {
+		printk(KERN_CONT ".. too many entries");
+		goto failed;
+	}
+
+	return 0;
+
+ failed:
+	printk(KERN_CONT ".. corrupted trace buffer .. ");
+	return -1;
+}
+
+/*
+ * Test the trace buffer to see if all the elements
+ * are still sane.
+ */
+static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
+{
+	unsigned long cnt = 0;
+	int cpu;
+	int ret = 0;
+
+	for_each_possible_cpu(cpu) {
+		if (!tr->data[cpu]->trace)
+			continue;
+
+		cnt += tr->data[cpu]->trace_idx;
+		printk("%d: count = %ld\n", cpu, cnt);
+
+		ret = trace_test_buffer_cpu(tr, tr->data[cpu]);
+		if (ret)
+			break;
+	}
+
+	if (count)
+		*count = cnt;
+
+	return ret;
+}
+
+#ifdef CONFIG_FTRACE
+/*
+ * Simple verification test of ftrace function tracer.
+ * Enable ftrace, sleep 1/10 second, and then read the trace
+ * buffer to see if all is in order.
+ */
+int
+trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long count;
+	int ret;
+
+	/* make sure functions have been recorded */
+	ret = ftrace_force_update();
+	if (ret) {
+		printk(KERN_CONT ".. ftraced failed .. ");
+		return ret;
+	}
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* Sleep for a 1/10 of a second */
+	msleep(100);
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check the trace buffer */
+	ret = trace_test_buffer(tr, &count);
+	trace->reset(tr);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+	}
+
+	return ret;
+}
+#endif /* CONFIG_FTRACE */
+
+#ifdef CONFIG_IRQSOFF_TRACER
+int
+trace_selftest_startup_irqsoff(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long save_max = tracing_max_latency;
+	unsigned long count;
+	int ret;
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* reset the max latency */
+	tracing_max_latency = 0;
+	/* disable interrupts for a bit */
+	local_irq_disable();
+	udelay(100);
+	local_irq_enable();
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (!ret)
+		ret = trace_test_buffer(&max_tr, &count);
+	trace->reset(tr);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+	}
+
+	tracing_max_latency = save_max;
+
+	return ret;
+}
+#endif /* CONFIG_IRQSOFF_TRACER */
+
+#ifdef CONFIG_PREEMPT_TRACER
+int
+trace_selftest_startup_preemptoff(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long save_max = tracing_max_latency;
+	unsigned long count;
+	int ret;
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* reset the max latency */
+	tracing_max_latency = 0;
+	/* disable preemption for a bit */
+	preempt_disable();
+	udelay(100);
+	preempt_enable();
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (!ret)
+		ret = trace_test_buffer(&max_tr, &count);
+	trace->reset(tr);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+	}
+
+	tracing_max_latency = save_max;
+
+	return ret;
+}
+#endif /* CONFIG_PREEMPT_TRACER */
+
+#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
+int
+trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long save_max = tracing_max_latency;
+	unsigned long count;
+	int ret;
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+
+	/* reset the max latency */
+	tracing_max_latency = 0;
+
+	/* disable preemption and interrupts for a bit */
+	preempt_disable();
+	local_irq_disable();
+	udelay(100);
+	preempt_enable();
+	/* reverse the order of preempt vs irqs */
+	local_irq_enable();
+
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (ret)
+		goto out;
+
+	ret = trace_test_buffer(&max_tr, &count);
+	if (ret)
+		goto out;
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+		goto out;
+	}
+
+	/* do the test by disabling interrupts first this time */
+	tracing_max_latency = 0;
+	tr->ctrl = 1;
+	trace->ctrl_update(tr);
+	preempt_disable();
+	local_irq_disable();
+	udelay(100);
+	preempt_enable();
+	/* reverse the order of preempt vs irqs */
+	local_irq_enable();
+
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (ret)
+		goto out;
+
+	ret = trace_test_buffer(&max_tr, &count);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+		goto out;
+	}
+
+ out:
+	trace->reset(tr);
+	tracing_max_latency = save_max;
+
+	return ret;
+}
+#endif /* CONFIG_IRQSOFF_TRACER && CONFIG_PREEMPT_TRACER */
+
+#ifdef CONFIG_SCHED_TRACER
+static int trace_wakeup_test_thread(void *data)
+{
+	struct completion *x = data;
+
+	/* Make this a RT thread, doesn't need to be too high */
+
+	rt_mutex_setprio(current, MAX_RT_PRIO - 5);
+
+	/* Make it know we have a new prio */
+	complete(x);
+
+	/* now go to sleep and let the test wake us up */
+	set_current_state(TASK_INTERRUPTIBLE);
+	schedule();
+
+	/* we are awake, now wait to disappear */
+	while (!kthread_should_stop()) {
+		/*
+		 * This is an RT task, do short sleeps to let
+		 * others run.
+		 */
+		msleep(100);
+	}
+
+	return 0;
+}
+
+int
+trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long save_max = tracing_max_latency;
+	struct task_struct *p;
+	struct completion isrt;
+	unsigned long count;
+	int ret;
+
+	init_completion(&isrt);
+
+	/* create a high prio thread */
+	p = kthread_run(trace_wakeup_test_thread, &isrt, "ftrace-test");
+	if (!IS_ERR(p)) {
+		printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
+		return -1;
+	}
+
+	/* make sure the thread is running at an RT prio */
+	wait_for_completion(&isrt);
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* reset the max latency */
+	tracing_max_latency = 0;
+
+	/* sleep to let the RT thread sleep too */
+	msleep(100);
+
+	/*
+	 * Yes this is slightly racy. It is possible that for some
+	 * strange reason that the RT thread we created, did not
+	 * call schedule for 100ms after doing the completion,
+	 * and we do a wakeup on a task that already is awake.
+	 * But that is extremely unlikely, and the worst thing that
+	 * happens in such a case, is that we disable tracing.
+	 * Honestly, if this race does happen something is horrible
+	 * wrong with the system.
+	 */
+
+	wake_up_process(p);
+
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (!ret)
+		ret = trace_test_buffer(&max_tr, &count);
+
+
+	trace->reset(tr);
+
+	tracing_max_latency = save_max;
+
+	/* kill the thread */
+	kthread_stop(p);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+	}
+
+	return ret;
+}
+#endif /* CONFIG_SCHED_TRACER */
+
+#ifdef CONFIG_CONTEXT_SWITCH_TRACER
+int
+trace_selftest_startup_sched_switch(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long count;
+	int ret;
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* Sleep for a 1/10 of a second */
+	msleep(100);
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check the trace buffer */
+	ret = trace_test_buffer(tr, &count);
+	trace->reset(tr);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+	}
+
+	return ret;
+}
+#endif /* CONFIG_CONTEXT_SWITCH_TRACER */
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+#endif /* CONFIG_DYNAMIC_FTRACE */