ftrace: startup tester on dynamic tracing.
This patch adds a startup self test on dynamic code modification
and filters. The test filters on a specific function, makes sure that
no other function is traced, exectutes the function, then makes sure that
the function is traced.
This patch also fixes a slight bug with the ftrace selftest, where
tracer_enabled was not being set.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 953a36d..a842d96 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -55,6 +55,7 @@
};
int ftrace_force_update(void);
+void ftrace_set_filter(unsigned char *buf, int len, int reset);
/* defined in arch */
extern int ftrace_ip_converted(unsigned long ip);
@@ -70,6 +71,7 @@
extern void mcount_call(void);
#else
# define ftrace_force_update() ({ 0; })
+# define ftrace_set_filter(buf, len, reset) do { } while (0)
#endif
static inline void tracer_disable(void)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6d4d2e8..5e9389f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1010,6 +1010,25 @@
return ret;
}
+/**
+ * ftrace_set_filter - set a function to filter on in ftrace
+ * @buf - the string that holds the function filter text.
+ * @len - the length of the string.
+ * @reset - non zero to reset all filters before applying this filter.
+ *
+ * Filters denote which functions should be enabled when tracing is enabled.
+ * If @buf is NULL and reset is set, all functions will be enabled for tracing.
+ */
+notrace void ftrace_set_filter(unsigned char *buf, int len, int reset)
+{
+ mutex_lock(&ftrace_filter_lock);
+ if (reset)
+ ftrace_filter_reset();
+ if (buf)
+ ftrace_match(buf, len);
+ mutex_unlock(&ftrace_filter_lock);
+}
+
static int notrace
ftrace_filter_release(struct inode *inode, struct file *file)
{
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index c01874c..4c8a1b2 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -99,6 +99,100 @@
}
#ifdef CONFIG_FTRACE
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
+#define __STR(x) #x
+#define STR(x) __STR(x)
+static int DYN_FTRACE_TEST_NAME(void)
+{
+ /* used to call mcount */
+ return 0;
+}
+
+/* Test dynamic code modification and ftrace filters */
+int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
+ struct trace_array *tr,
+ int (*func)(void))
+{
+ unsigned long count;
+ int ret;
+ int save_ftrace_enabled = ftrace_enabled;
+ int save_tracer_enabled = tracer_enabled;
+
+ /* The ftrace test PASSED */
+ printk(KERN_CONT "PASSED\n");
+ pr_info("Testing dynamic ftrace: ");
+
+ /* enable tracing, and record the filter function */
+ ftrace_enabled = 1;
+ tracer_enabled = 1;
+
+ /* passed in by parameter to fool gcc from optimizing */
+ func();
+
+ /* update the records */
+ ret = ftrace_force_update();
+ if (ret) {
+ printk(KERN_CONT ".. ftraced failed .. ");
+ return ret;
+ }
+
+ /* filter only on our function */
+ ftrace_set_filter(STR(DYN_FTRACE_TEST_NAME),
+ sizeof(STR(DYN_FTRACE_TEST_NAME)), 1);
+
+ /* enable tracing */
+ tr->ctrl = 1;
+ trace->init(tr);
+ /* Sleep for a 1/10 of a second */
+ msleep(100);
+
+ /* we should have nothing in the buffer */
+ ret = trace_test_buffer(tr, &count);
+ if (ret)
+ goto out;
+
+ if (count) {
+ ret = -1;
+ printk(KERN_CONT ".. filter did not filter .. ");
+ goto out;
+ }
+
+ /* call our function again */
+ func();
+
+ /* sleep again */
+ msleep(100);
+
+ /* stop the tracing. */
+ tr->ctrl = 0;
+ trace->ctrl_update(tr);
+ ftrace_enabled = 0;
+
+ /* check the trace buffer */
+ ret = trace_test_buffer(tr, &count);
+ trace->reset(tr);
+
+ /* we should only have one item */
+ if (!ret && count != 1) {
+ printk(KERN_CONT ".. filter failed ..");
+ ret = -1;
+ goto out;
+ }
+ out:
+ ftrace_enabled = save_ftrace_enabled;
+ tracer_enabled = save_tracer_enabled;
+
+ /* Enable tracing on all functions again */
+ ftrace_set_filter(NULL, 0, 1);
+
+ return ret;
+}
+#else
+# define trace_selftest_startup_dynamic_tracing(trace, tr, func) ({ 0; })
+#endif /* CONFIG_DYNAMIC_FTRACE */
/*
* Simple verification test of ftrace function tracer.
* Enable ftrace, sleep 1/10 second, and then read the trace
@@ -109,8 +203,13 @@
{
unsigned long count;
int ret;
+ int save_ftrace_enabled = ftrace_enabled;
+ int save_tracer_enabled = tracer_enabled;
- /* make sure functions have been recorded */
+ /* make sure msleep has been recorded */
+ msleep(1);
+
+ /* force the recorded functions to be traced */
ret = ftrace_force_update();
if (ret) {
printk(KERN_CONT ".. ftraced failed .. ");
@@ -119,6 +218,7 @@
/* start the tracing */
ftrace_enabled = 1;
+ tracer_enabled = 1;
tr->ctrl = 1;
trace->init(tr);
@@ -136,8 +236,16 @@
if (!ret && !count) {
printk(KERN_CONT ".. no entries found ..");
ret = -1;
+ goto out;
}
+ ret = trace_selftest_startup_dynamic_tracing(trace, tr,
+ DYN_FTRACE_TEST_NAME);
+
+ out:
+ ftrace_enabled = save_ftrace_enabled;
+ tracer_enabled = save_tracer_enabled;
+
return ret;
}
#endif /* CONFIG_FTRACE */
@@ -415,6 +523,3 @@
return ret;
}
#endif /* CONFIG_CONTEXT_SWITCH_TRACER */
-
-#ifdef CONFIG_DYNAMIC_FTRACE
-#endif /* CONFIG_DYNAMIC_FTRACE */