Initial commit: Linux kernel 4.19 for Unplugged OS

scripts/tracing/draw_functrace.py

@@ -0,0 +1,129 @@
+#!/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
+	# mount -t debugfs nodev /sys/kernel/debug
+	# echo function > /sys/kernel/debug/tracing/current_tracer
+	$ cat /sys/kernel/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()

scripts/tracing/ftrace-bisect.sh

@@ -0,0 +1,116 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Here's how to use this:
+#
+# This script is used to help find functions that are being traced by function
+# tracer or function graph tracing that causes the machine to reboot, hang, or
+# crash. Here's the steps to take.
+#
+# First, determine if function tracing is working with a single function:
+#
+#   (note, if this is a problem with function_graph tracing, then simply
+#    replace "function" with "function_graph" in the following steps).
+#
+#  # cd /sys/kernel/debug/tracing
+#  # echo schedule > set_ftrace_filter
+#  # echo function > current_tracer
+#
+# If this works, then we know that something is being traced that shouldn't be.
+#
+#  # echo nop > current_tracer
+#
+#  # cat available_filter_functions > ~/full-file
+#  # ftrace-bisect ~/full-file ~/test-file ~/non-test-file
+#  # cat ~/test-file > set_ftrace_filter
+#
+# *** Note *** this will take several minutes. Setting multiple functions is
+# an O(n^2) operation, and we are dealing with thousands of functions. So go
+# have  coffee, talk with your coworkers, read facebook. And eventually, this
+# operation will end.
+#
+#  # echo function > current_tracer
+#
+# If it crashes, we know that ~/test-file has a bad function.
+#
+#   Reboot back to test kernel.
+#
+#     # cd /sys/kernel/debug/tracing
+#     # mv ~/test-file ~/full-file
+#
+# If it didn't crash.
+#
+#     # echo nop > current_tracer
+#     # mv ~/non-test-file ~/full-file
+#
+# Get rid of the other test file from previous run (or save them off somewhere).
+#  # rm -f ~/test-file ~/non-test-file
+#
+# And start again:
+#
+#  # ftrace-bisect ~/full-file ~/test-file ~/non-test-file
+#
+# The good thing is, because this cuts the number of functions in ~/test-file
+# by half, the cat of it into set_ftrace_filter takes half as long each
+# iteration, so don't talk so much at the water cooler the second time.
+#
+# Eventually, if you did this correctly, you will get down to the problem
+# function, and all we need to do is to notrace it.
+#
+# The way to figure out if the problem function is bad, just do:
+#
+#  # echo <problem-function> > set_ftrace_notrace
+#  # echo > set_ftrace_filter
+#  # echo function > current_tracer
+#
+# And if it doesn't crash, we are done.
+#
+# If it does crash, do this again (there's more than one problem function)
+# but you need to echo the problem function(s) into set_ftrace_notrace before
+# enabling function tracing in the above steps. Or if you can compile the
+# kernel, annotate the problem functions with "notrace" and start again.
+#
+
+
+if [ $# -ne 3 ]; then
+  echo 'usage: ftrace-bisect full-file test-file  non-test-file'
+  exit
+fi
+
+full=$1
+test=$2
+nontest=$3
+
+x=`cat $full | wc -l`
+if [ $x -eq 1 ]; then
+	echo "There's only one function left, must be the bad one"
+	cat $full
+	exit 0
+fi
+
+let x=$x/2
+let y=$x+1
+
+if [ ! -f $full ]; then
+	echo "$full does not exist"
+	exit 1
+fi
+
+if [ -f $test ]; then
+	echo -n "$test exists, delete it? [y/N]"
+	read a
+	if [ "$a" != "y" -a "$a" != "Y" ]; then
+		exit 1
+	fi
+fi
+
+if [ -f $nontest ]; then
+	echo -n "$nontest exists, delete it? [y/N]"
+	read a
+	if [ "$a" != "y" -a "$a" != "Y" ]; then
+		exit 1
+	fi
+fi
+
+sed -ne "1,${x}p" $full > $test
+sed -ne "$y,\$p" $full > $nontest