Merge branch 'tracing/ftrace' into auto-ftrace-next

4 files changed, 168 insertions, 3 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 703eb53cfa2b..899ec4b26b6c 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -181,6 +181,8 @@ static inline void __ftrace_enabled_restore(int enabled)
 #endif
 
 #ifdef CONFIG_TRACING
+extern int ftrace_dump_on_oops;
+
 extern void
 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
 
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 9d048fa2d902..6b6b727258b5 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -484,6 +484,16 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= &ftrace_enable_sysctl,
 	},
 #endif
+#ifdef CONFIG_TRACING
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "ftrace_dump_on_opps",
+		.data		= &ftrace_dump_on_oops,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
+#endif
 #ifdef CONFIG_MODULES
 	{
 		.ctl_name	= KERN_MODPROBE,
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8a499e2adaec..bdb1df00fb10 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -64,6 +64,28 @@ static cpumask_t __read_mostly		tracing_buffer_mask;
 
 static int tracing_disabled = 1;
 
+/*
+ * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
+ *
+ * If there is an oops (or kernel panic) and the ftrace_dump_on_oops
+ * is set, then ftrace_dump is called. This will output the contents
+ * of the ftrace buffers to the console.  This is very useful for
+ * capturing traces that lead to crashes and outputing it to a
+ * serial console.
+ *
+ * It is default off, but you can enable it with either specifying
+ * "ftrace_dump_on_oops" in the kernel command line, or setting
+ * /proc/sys/kernel/ftrace_dump_on_oops to true.
+ */
+int ftrace_dump_on_oops;
+
+static int __init set_ftrace_dump_on_oops(char *str)
+{
+	ftrace_dump_on_oops = 1;
+	return 1;
+}
+__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
+
 long
 ns2usecs(cycle_t nsec)
 {
@@ -3025,7 +3047,8 @@ EXPORT_SYMBOL_GPL(__ftrace_printk);
 static int trace_panic_handler(struct notifier_block *this,
 			       unsigned long event, void *unused)
 {
-	ftrace_dump();
+	if (ftrace_dump_on_oops)
+		ftrace_dump();
 	return NOTIFY_OK;
 }
 
@@ -3041,7 +3064,8 @@ static int trace_die_handler(struct notifier_block *self,
 {
 	switch (val) {
 	case DIE_OOPS:
-		ftrace_dump();
+		if (ftrace_dump_on_oops)
+			ftrace_dump();
 		break;
 	default:
 		break;
@@ -3082,7 +3106,6 @@ trace_printk_seq(struct trace_seq *s)
 	trace_seq_reset(s);
 }
 
-
 void ftrace_dump(void)
 {
 	static DEFINE_SPINLOCK(ftrace_dump_lock);
diff --git a/scripts/tracing/draw_functrace.py b/scripts/tracing/draw_functrace.py
new file mode 100644
index 000000000000..902f9a992620
--- /dev/null
+++ b/scripts/tracing/draw_functrace.py
@@ -0,0 +1,130 @@
+#!/usr/bin/python
+
+"""
+Copyright 2008 (c) Frederic Weisbecker <fweisbec@gmail.com>
+Licensed under the terms of the GNU GPL License version 2
+
+This script parses a trace provided by the function tracer in
+kernel/trace/trace_functions.c
+The resulted trace is processed into a tree to produce a more human
+view of the call stack by drawing textual but hierarchical tree of
+calls. Only the functions's names and the the call time are provided.
+
+Usage:
+	Be sure that you have CONFIG_FUNCTION_TRACER
+	# mkdir /debugfs
+	# mount -t debug debug /debug
+	# echo function > /debug/tracing/current_tracer
+	$ cat /debug/tracing/trace_pipe > ~/raw_trace_func
+	Wait some times but not too much, the script is a bit slow.
+	Break the pipe (Ctrl + Z)
+	$ scripts/draw_functrace.py < raw_trace_func > draw_functrace
+	Then you have your drawn trace in draw_functrace
+"""
+
+
+import sys, re
+
+class CallTree:
+	""" This class provides a tree representation of the functions
+		call stack. If a function has no parent in the kernel (interrupt,
+		syscall, kernel thread...) then it is attached to a virtual parent
+		called ROOT.
+	"""
+	ROOT = None
+
+	def __init__(self, func, time = None, parent = None):
+		self._func = func
+		self._time = time
+		if parent is None:
+			self._parent = CallTree.ROOT
+		else:
+			self._parent = parent
+		self._children = []
+
+	def calls(self, func, calltime):
+		""" If a function calls another one, call this method to insert it
+			into the tree at the appropriate place.
+			@return: A reference to the newly created child node.
+		"""
+		child = CallTree(func, calltime, self)
+		self._children.append(child)
+		return child
+
+	def getParent(self, func):
+		""" Retrieve the last parent of the current node that
+			has the name given by func. If this function is not
+			on a parent, then create it as new child of root
+			@return: A reference to the parent.
+		"""
+		tree = self
+		while tree != CallTree.ROOT and tree._func != func:
+			tree = tree._parent
+		if tree == CallTree.ROOT:
+			child = CallTree.ROOT.calls(func, None)
+			return child
+		return tree
+
+	def __repr__(self):
+		return self.__toString("", True)
+
+	def __toString(self, branch, lastChild):
+		if self._time is not None:
+			s = "%s----%s (%s)\n" % (branch, self._func, self._time)
+		else:
+			s = "%s----%s\n" % (branch, self._func)
+
+		i = 0
+		if lastChild:
+			branch = branch[:-1] + " "
+		while i < len(self._children):
+			if i != len(self._children) - 1:
+				s += "%s" % self._children[i].__toString(branch +\
+								"    |", False)
+			else:
+				s += "%s" % self._children[i].__toString(branch +\
+								"    |", True)
+			i += 1
+		return s
+
+class BrokenLineException(Exception):
+	"""If the last line is not complete because of the pipe breakage,
+	   we want to stop the processing and ignore this line.
+	"""
+	pass
+
+class CommentLineException(Exception):
+	""" If the line is a comment (as in the beginning of the trace file),
+	    just ignore it.
+	"""
+	pass
+
+
+def parseLine(line):
+	line = line.strip()
+	if line.startswith("#"):
+		raise CommentLineException
+	m = re.match("[^]]+?\\] +([0-9.]+): (\\w+) <-(\\w+)", line)
+	if m is None:
+		raise BrokenLineException
+	return (m.group(1), m.group(2), m.group(3))
+
+
+def main():
+	CallTree.ROOT = CallTree("Root (Nowhere)", None, None)
+	tree = CallTree.ROOT
+
+	for line in sys.stdin:
+		try:
+			calltime, callee, caller = parseLine(line)
+		except BrokenLineException:
+			break
+		except CommentLineException:
+			continue
+		tree = tree.getParent(caller)
+		tree = tree.calls(callee, calltime)
+
+	print CallTree.ROOT
+
+if __name__ == "__main__":
+	main()