Commit 60a11774 authored by Steven Rostedt's avatar Steven Rostedt Committed by Thomas Gleixner
Browse files

ftrace: add self-tests


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent e1c08bdd
......@@ -105,3 +105,16 @@ config DYNAMIC_FTRACE
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.
......@@ -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 @@ int register_tracer(struct tracer *type)
}
}
#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 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
{
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 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
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 @@ static int show_traces_open(struct inode *inode, struct file *file)
{
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 @@ struct dentry *tracing_init_dentry(void)
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 @@ __init static int tracer_alloc_buffers(void)
void *array;
struct page *page;
int pages = 0;
int ret = -ENOMEM;
int i;
/* Allocate the first page for all buffers */
......@@ -1650,6 +1706,9 @@ __init static int tracer_alloc_buffers(void)
register_tracer(&no_tracer);
current_trace = &no_tracer;
/* All seems OK, enable tracing */
tracing_disabled = 0;
return 0;
free_buffers:
......@@ -1678,7 +1737,7 @@ __init static int tracer_alloc_buffers(void)
}
#endif
}
return -ENOMEM;
return ret;
}
device_initcall(tracer_alloc_buffers);
fs_initcall(tracer_alloc_buffers);
......@@ -99,6 +99,10 @@ struct tracer {
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 int unregister_tracer_switch(struct tracer_switch_ops *ops);
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 */
......@@ -63,6 +63,9 @@ static struct tracer function_trace __read_mostly =
.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)
......
......@@ -432,6 +432,9 @@ static struct tracer irqsoff_tracer __read_mostly =
.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 @@ static struct tracer preemptoff_tracer __read_mostly =
.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 @@ static struct tracer preemptirqsoff_tracer __read_mostly =
.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)
......
......@@ -107,6 +107,9 @@ static struct tracer sched_switch_trace __read_mostly =
.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)
......
......@@ -295,6 +295,9 @@ static struct tracer wakeup_tracer __read_mostly =
.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)
......
/* 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 */