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linux-next/scripts/decode_stacktrace.sh
Sasha Levin a5dc8300df scripts/decode_stacktrace: warn when modpath is needed but is unset
When a user tries to parse a symbol located inside a module he must have
modpath set. Otherwise, decode_stacktrace won't be able to parse the
symbol correctly.

Right now the failure is silent and easily missed by the user. What's
worse is that by the time the user realizes what happened (or someone on
LKML asks him to add the modpath and re-run), he might have already got
rid of the vmlinux/modules.

Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-15 15:37:24 -07:00

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#!/bin/bash
# SPDX-License-Identifier: GPL-2.0
# (c) 2014, Sasha Levin <sasha.levin@oracle.com>
#set -x
if [[ $# < 2 ]]; then
echo "Usage:"
echo " $0 [vmlinux] [base path] [modules path]"
exit 1
fi
vmlinux=$1
basepath=$2
modpath=$3
declare -A cache
declare -A modcache
parse_symbol() {
# The structure of symbol at this point is:
# ([name]+[offset]/[total length])
#
# For example:
# do_basic_setup+0x9c/0xbf
if [[ $module == "" ]] ; then
local objfile=$vmlinux
elif [[ "${modcache[$module]+isset}" == "isset" ]]; then
local objfile=${modcache[$module]}
else
if [[ $modpath == "" ]]; then
echo "WARNING! Modules path isn't set, but is needed to parse this symbol" >&2
return
fi
local objfile=$(find "$modpath" -name "${module//_/[-_]}.ko*" -print -quit)
[[ $objfile == "" ]] && return
modcache[$module]=$objfile
fi
# Remove the englobing parenthesis
symbol=${symbol#\(}
symbol=${symbol%\)}
# Strip segment
local segment
if [[ $symbol == *:* ]] ; then
segment=${symbol%%:*}:
symbol=${symbol#*:}
fi
# Strip the symbol name so that we could look it up
local name=${symbol%+*}
# Use 'nm vmlinux' to figure out the base address of said symbol.
# It's actually faster to call it every time than to load it
# all into bash.
if [[ "${cache[$module,$name]+isset}" == "isset" ]]; then
local base_addr=${cache[$module,$name]}
else
local base_addr=$(nm "$objfile" | grep -i ' t ' | awk "/ $name\$/ {print \$1}" | head -n1)
cache[$module,$name]="$base_addr"
fi
# Let's start doing the math to get the exact address into the
# symbol. First, strip out the symbol total length.
local expr=${symbol%/*}
# Now, replace the symbol name with the base address we found
# before.
expr=${expr/$name/0x$base_addr}
# Evaluate it to find the actual address
expr=$((expr))
local address=$(printf "%x\n" "$expr")
# Pass it to addr2line to get filename and line number
# Could get more than one result
if [[ "${cache[$module,$address]+isset}" == "isset" ]]; then
local code=${cache[$module,$address]}
else
local code=$(${CROSS_COMPILE}addr2line -i -e "$objfile" "$address")
cache[$module,$address]=$code
fi
# addr2line doesn't return a proper error code if it fails, so
# we detect it using the value it prints so that we could preserve
# the offset/size into the function and bail out
if [[ $code == "??:0" ]]; then
return
fi
# Strip out the base of the path
code=${code#$basepath/}
# In the case of inlines, move everything to same line
code=${code//$'\n'/' '}
# Replace old address with pretty line numbers
symbol="$segment$name ($code)"
}
decode_code() {
local scripts=`dirname "${BASH_SOURCE[0]}"`
echo "$1" | $scripts/decodecode
}
handle_line() {
local words
# Tokenize
read -a words <<<"$1"
# Remove hex numbers. Do it ourselves until it happens in the
# kernel
# We need to know the index of the last element before we
# remove elements because arrays are sparse
local last=$(( ${#words[@]} - 1 ))
for i in "${!words[@]}"; do
# Remove the address
if [[ ${words[$i]} =~ \[\<([^]]+)\>\] ]]; then
unset words[$i]
fi
# Format timestamps with tabs
if [[ ${words[$i]} == \[ && ${words[$i+1]} == *\] ]]; then
unset words[$i]
words[$i+1]=$(printf "[%13s\n" "${words[$i+1]}")
fi
done
if [[ ${words[$last]} =~ \[([^]]+)\] ]]; then
module=${words[$last]}
module=${module#\[}
module=${module%\]}
symbol=${words[$last-1]}
unset words[$last-1]
else
# The symbol is the last element, process it
symbol=${words[$last]}
module=
fi
unset words[$last]
parse_symbol # modifies $symbol
# Add up the line number to the symbol
echo "${words[@]}" "$symbol $module"
}
while read line; do
# Let's see if we have an address in the line
if [[ $line =~ \[\<([^]]+)\>\] ]] ||
[[ $line =~ [^+\ ]+\+0x[0-9a-f]+/0x[0-9a-f]+ ]]; then
# Translate address to line numbers
handle_line "$line"
# Is it a code line?
elif [[ $line == *Code:* ]]; then
decode_code "$line"
else
# Nothing special in this line, show it as is
echo "$line"
fi
done