linux/scripts/tracing/ftrace-bisect.sh

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ftrace/scripts: Add helper script to bisect function tracing problem functions Every so often, with a special config or a architecture change, running function or function_graph tracing can cause the machien to hard reboot, crash, or simply hard lockup. There's some functions in the function graph tracer that can not be traced otherwise it causes the function tracer to recurse before the recursion protection mechanisms are in place. When this occurs, using the dynamic ftrace featuer that allows limiting what actually gets traced can be used to bisect down to the problem function. This adds a script that helps with this process in the scripts/tracing directory, called ftrace-bisect.sh The set up is to read all the functions that can be traced from available_filter_functions into a file (full_file). Then run this script passing it the full_file and a "test_file" and "non_test_file", where the test_file will be add to set_ftrace_filter. What ftarce_bisect.sh does, is to copy half of the functions in full_file into the test_file and the other half into the non_test_file. This way, one can cat the test_file into the set_ftrace_filter functions and only test the functions that are in that file. If it works, then we run the process again after copying non_test_file to full_file and repeating the process. If the system crashed, then the bad function is in the test_file and after a reboot, the test_file becomes the new full_file in the next iteration. When we get down to a single function in the full_file, then ftrace_bisect.sh will report that as the bad function. Full documentation of how to use this simple script is within the script file itself. Link: http://lkml.kernel.org/r/20160920100716.131d3647@gandalf.local.home Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2016-09-21 17:43:48 +00:00
#!/bin/bash
License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
# SPDX-License-Identifier: GPL-2.0
ftrace/scripts: Add helper script to bisect function tracing problem functions Every so often, with a special config or a architecture change, running function or function_graph tracing can cause the machien to hard reboot, crash, or simply hard lockup. There's some functions in the function graph tracer that can not be traced otherwise it causes the function tracer to recurse before the recursion protection mechanisms are in place. When this occurs, using the dynamic ftrace featuer that allows limiting what actually gets traced can be used to bisect down to the problem function. This adds a script that helps with this process in the scripts/tracing directory, called ftrace-bisect.sh The set up is to read all the functions that can be traced from available_filter_functions into a file (full_file). Then run this script passing it the full_file and a "test_file" and "non_test_file", where the test_file will be add to set_ftrace_filter. What ftarce_bisect.sh does, is to copy half of the functions in full_file into the test_file and the other half into the non_test_file. This way, one can cat the test_file into the set_ftrace_filter functions and only test the functions that are in that file. If it works, then we run the process again after copying non_test_file to full_file and repeating the process. If the system crashed, then the bad function is in the test_file and after a reboot, the test_file becomes the new full_file in the next iteration. When we get down to a single function in the full_file, then ftrace_bisect.sh will report that as the bad function. Full documentation of how to use this simple script is within the script file itself. Link: http://lkml.kernel.org/r/20160920100716.131d3647@gandalf.local.home Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2016-09-21 17:43:48 +00:00
#
# 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