From 92e47eba76d4a6a4b1d0647700a0c6d89fcf5829 Mon Sep 17 00:00:00 2001
From: Mark Charlebois <charlebm@gmail.com>
Date: Mon, 23 Nov 2015 13:13:34 -0800
Subject: [PATCH] Added tool to decode stack backtraces

Signed-off-by: Mark Charlebois <charlebm@gmail.com>
---
 Tools/decode_backtrace.py | 117 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100755 Tools/decode_backtrace.py

diff --git a/Tools/decode_backtrace.py b/Tools/decode_backtrace.py
new file mode 100755
index 0000000000..469e891110
--- /dev/null
+++ b/Tools/decode_backtrace.py
@@ -0,0 +1,117 @@
+#!/usr/bin/env python
+############################################################################
+#
+# Copyright (C) 2015 Mark Charlebois. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name PX4 nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+import os
+import subprocess
+
+# The PX4_BACKTRACE() macro can be used to generate backtraces in the 
+# running code. These provide the addresses only. This utility can be
+# used to decode the backtrace into a readable form:
+#
+# Example
+# If the following lines were pasted into the shell after running decode_backtrace.py
+# INFO  Backtrace: 10
+# INFO  ./mainapp(px4_backtrace+0x27) [0x42b0d1]
+# INFO  ./mainapp() [0x42d44d]
+# INFO  ./mainapp() [0x42d3c6]
+#
+# The output would be:
+# 0x42b0d1 _sighandler (0x42b15b)
+# 0x42d44d ACCELSIM::devRead(void*, unsigned long) (0x42d4be)
+# 0x42d3c6 ACCELSIM::stop() (0x42d442)
+#
+# The output is:
+# <backtrace address> <function name> (<function address>)
+
+
+def usage():
+	msg = """
+Usage: Tools/decode_backtrace.py <builddir>
+
+This will load the symbols for <builddir>/src/firmware/posix/mainapp
+The user just needs to copy and paste the backtrace into the terminal
+where decode_backtrace.py is running.
+
+"""
+	print msg
+
+funcaddr = []
+func = []
+
+# Load the symbols from the binary
+def load_symbol_map():
+	output = subprocess.check_output(["nm", "-p", "-C", os.sys.argv[1]+"/src/firmware/posix/mainapp"])
+	data = output.split("\n")
+	data.sort()
+
+	i = 0
+	for line in data:
+		if line.startswith("0"):
+			funcaddr.append(int(line[0:16],16))
+			func.append(line[19:])
+			#print(hex(funcaddr[i]), func[i])
+			i = i+1
+
+# Find the function for the specified call stack address
+def lookup(addr):
+	i=0
+	while i < len(funcaddr) and addr > funcaddr[i]:
+		i=i+1
+	if i >= len(funcaddr):
+		return -1
+	return i
+
+if len(os.sys.argv) != 2:
+	usage()
+	raise SystemExit
+
+load_symbol_map()
+
+print
+print "Paste the backtrace here. Use Ctrl-C to exit."
+print
+while 1:
+	# Wait for user to paste the backtrace into the shell
+	line = raw_input()
+	tmp = line.split("[")
+	if len(tmp) == 1:
+		if len(line.split("Backtrace:")) > 1:
+			print
+		continue
+	addrstr = tmp[1].split("]")[0]
+	addr = int(addrstr, 16)
+	idx = lookup(addr)
+	if idx >=  0:
+		print hex(addr), func[idx], "({0})".format(hex(funcaddr[idx]))
+