ftrace: add self-tests
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index cad9db1..3f73a17 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -105,3 +105,16 @@
wakes up once a second and checks to see if any ftrace calls
were made. If so, it runs stop_machine (stops all CPUS)
and modifies the code to jump over the call to ftrace.
+
+config FTRACE_SELFTEST
+ bool
+
+config FTRACE_STARTUP_TEST
+ bool "Perform a startup test on ftrace"
+ depends on TRACING
+ select FTRACE_SELFTEST
+ help
+ This option performs a series of startup tests on ftrace. On bootup
+ a series of tests are made to verify that the tracer is
+ functioning properly. It will do tests on all the configured
+ tracers of ftrace.
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9bad237..f6d026f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -32,6 +32,8 @@
unsigned long __read_mostly tracing_max_latency = (cycle_t)ULONG_MAX;
unsigned long __read_mostly tracing_thresh;
+static int tracing_disabled = 1;
+
static long notrace
ns2usecs(cycle_t nsec)
{
@@ -217,11 +219,48 @@
}
}
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+ if (type->selftest) {
+ struct tracer *saved_tracer = current_trace;
+ struct trace_array_cpu *data;
+ struct trace_array *tr = &global_trace;
+ int saved_ctrl = tr->ctrl;
+ int i;
+ /*
+ * Run a selftest on this tracer.
+ * Here we reset the trace buffer, and set the current
+ * tracer to be this tracer. The tracer can then run some
+ * internal tracing to verify that everything is in order.
+ * If we fail, we do not register this tracer.
+ */
+ for_each_possible_cpu(i) {
+ if (!data->trace)
+ continue;
+ data = tr->data[i];
+ tracing_reset(data);
+ }
+ current_trace = type;
+ tr->ctrl = 0;
+ /* the test is responsible for initializing and enabling */
+ pr_info("Testing tracer %s: ", type->name);
+ ret = type->selftest(type, tr);
+ /* the test is responsible for resetting too */
+ current_trace = saved_tracer;
+ tr->ctrl = saved_ctrl;
+ if (ret) {
+ printk(KERN_CONT "FAILED!\n");
+ goto out;
+ }
+ printk(KERN_CONT "PASSED\n");
+ }
+#endif
+
type->next = trace_types;
trace_types = type;
len = strlen(type->name);
if (len > max_tracer_type_len)
max_tracer_type_len = len;
+
out:
mutex_unlock(&trace_types_lock);
@@ -985,6 +1024,11 @@
{
struct trace_iterator *iter;
+ if (tracing_disabled) {
+ *ret = -ENODEV;
+ return NULL;
+ }
+
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter) {
*ret = -ENOMEM;
@@ -1023,6 +1067,9 @@
int tracing_open_generic(struct inode *inode, struct file *filp)
{
+ if (tracing_disabled)
+ return -ENODEV;
+
filp->private_data = inode->i_private;
return 0;
}
@@ -1128,6 +1175,9 @@
{
int ret;
+ if (tracing_disabled)
+ return -ENODEV;
+
ret = seq_open(file, &show_traces_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
@@ -1452,6 +1502,11 @@
return d_tracer;
}
+#ifdef CONFIG_FTRACE_SELFTEST
+/* Let selftest have access to static functions in this file */
+#include "trace_selftest.c"
+#endif
+
static __init void tracer_init_debugfs(void)
{
struct dentry *d_tracer;
@@ -1585,6 +1640,7 @@
void *array;
struct page *page;
int pages = 0;
+ int ret = -ENOMEM;
int i;
/* Allocate the first page for all buffers */
@@ -1650,6 +1706,9 @@
register_tracer(&no_tracer);
current_trace = &no_tracer;
+ /* All seems OK, enable tracing */
+ tracing_disabled = 0;
+
return 0;
free_buffers:
@@ -1678,7 +1737,7 @@
}
#endif
}
- return -ENOMEM;
+ return ret;
}
-device_initcall(tracer_alloc_buffers);
+fs_initcall(tracer_alloc_buffers);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 83e257e..88edbf1 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -99,6 +99,10 @@
void (*start)(struct trace_iterator *iter);
void (*stop)(struct trace_iterator *iter);
void (*ctrl_update)(struct trace_array *tr);
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+ int (*selftest)(struct tracer *trace,
+ struct trace_array *tr);
+#endif
struct tracer *next;
int print_max;
};
@@ -185,4 +189,31 @@
extern unsigned long ftrace_update_tot_cnt;
#endif
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+#ifdef CONFIG_FTRACE
+extern int trace_selftest_startup_function(struct tracer *trace,
+ struct trace_array *tr);
+#endif
+#ifdef CONFIG_IRQSOFF_TRACER
+extern int trace_selftest_startup_irqsoff(struct tracer *trace,
+ struct trace_array *tr);
+#endif
+#ifdef CONFIG_PREEMPT_TRACER
+extern int trace_selftest_startup_preemptoff(struct tracer *trace,
+ struct trace_array *tr);
+#endif
+#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
+extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace,
+ struct trace_array *tr);
+#endif
+#ifdef CONFIG_SCHED_TRACER
+extern int trace_selftest_startup_wakeup(struct tracer *trace,
+ struct trace_array *tr);
+#endif
+#ifdef CONFIG_CONTEXT_SWITCH_TRACER
+extern int trace_selftest_startup_sched_switch(struct tracer *trace,
+ struct trace_array *tr);
+#endif
+#endif /* CONFIG_FTRACE_STARTUP_TEST */
+
#endif /* _LINUX_KERNEL_TRACE_H */
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 82988c5..5d8ad7a 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -63,6 +63,9 @@
.init = function_trace_init,
.reset = function_trace_reset,
.ctrl_update = function_trace_ctrl_update,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_function,
+#endif
};
static __init int init_function_trace(void)
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 74165f6..14183b8 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -432,6 +432,9 @@
.close = irqsoff_tracer_close,
.ctrl_update = irqsoff_tracer_ctrl_update,
.print_max = 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_irqsoff,
+#endif
};
# define register_irqsoff(trace) register_tracer(&trace)
#else
@@ -455,6 +458,9 @@
.close = irqsoff_tracer_close,
.ctrl_update = irqsoff_tracer_ctrl_update,
.print_max = 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_preemptoff,
+#endif
};
# define register_preemptoff(trace) register_tracer(&trace)
#else
@@ -480,6 +486,9 @@
.close = irqsoff_tracer_close,
.ctrl_update = irqsoff_tracer_ctrl_update,
.print_max = 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_preemptirqsoff,
+#endif
};
# define register_preemptirqsoff(trace) register_tracer(&trace)
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 2715267..6c92841 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -107,6 +107,9 @@
.init = sched_switch_trace_init,
.reset = sched_switch_trace_reset,
.ctrl_update = sched_switch_trace_ctrl_update,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_sched_switch,
+#endif
};
__init static int init_sched_switch_trace(void)
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 7c3ccef..3d10ff0 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -295,6 +295,9 @@
.close = wakeup_tracer_close,
.ctrl_update = wakeup_tracer_ctrl_update,
.print_max = 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+ .selftest = trace_selftest_startup_wakeup,
+#endif
};
__init static int init_wakeup_tracer(void)
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
new file mode 100644
index 0000000..ef4d3cc
--- /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 */