117 lines
3.1 KiB
Bash
117 lines
3.1 KiB
Bash
|
#!/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
|