ftrace: add debugfs entry 'failures'
Identify functions which had their mcount call-site updates failed. This can
help us track functions which ftrace shouldn't fiddle with, and are thus not
being traced. If there is no race with any external agent which is modifying
the mcount call-site, then this file displays no entries (normal case).
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a8929e4..ad568c7 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -768,6 +768,7 @@
FTRACE_ITER_FILTER = (1 << 0),
FTRACE_ITER_CONT = (1 << 1),
FTRACE_ITER_NOTRACE = (1 << 2),
+ FTRACE_ITER_FAILURES = (1 << 3),
};
#define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
@@ -799,9 +800,16 @@
}
} else {
rec = &iter->pg->records[iter->idx++];
- if ((rec->flags & FTRACE_FL_FAILED) ||
+ if ((!(iter->flags & FTRACE_ITER_FAILURES) &&
+ (rec->flags & FTRACE_FL_FAILED)) ||
+
+ ((iter->flags & FTRACE_ITER_FAILURES) &&
+ (!(rec->flags & FTRACE_FL_FAILED) ||
+ (rec->flags & FTRACE_FL_FREE))) ||
+
((iter->flags & FTRACE_ITER_FILTER) &&
!(rec->flags & FTRACE_FL_FILTER)) ||
+
((iter->flags & FTRACE_ITER_NOTRACE) &&
!(rec->flags & FTRACE_FL_NOTRACE))) {
rec = NULL;
@@ -896,6 +904,24 @@
return 0;
}
+static int
+ftrace_failures_open(struct inode *inode, struct file *file)
+{
+ int ret;
+ struct seq_file *m;
+ struct ftrace_iterator *iter;
+
+ ret = ftrace_avail_open(inode, file);
+ if (!ret) {
+ m = (struct seq_file *)file->private_data;
+ iter = (struct ftrace_iterator *)m->private;
+ iter->flags = FTRACE_ITER_FAILURES;
+ }
+
+ return ret;
+}
+
+
static void ftrace_filter_reset(int enable)
{
struct ftrace_page *pg;
@@ -1309,6 +1335,13 @@
.release = ftrace_avail_release,
};
+static struct file_operations ftrace_failures_fops = {
+ .open = ftrace_failures_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = ftrace_avail_release,
+};
+
static struct file_operations ftrace_filter_fops = {
.open = ftrace_filter_open,
.read = ftrace_regex_read,
@@ -1386,6 +1419,11 @@
pr_warning("Could not create debugfs "
"'available_filter_functions' entry\n");
+ entry = debugfs_create_file("failures", 0444,
+ d_tracer, NULL, &ftrace_failures_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs 'failures' entry\n");
+
entry = debugfs_create_file("set_ftrace_filter", 0644, d_tracer,
NULL, &ftrace_filter_fops);
if (!entry)
