From 1d1a0e7c5100d332583e20b40aa8c0a8ed3d7849 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Thu, 12 May 2022 12:05:27 -0700 Subject: scripts/faddr2line: Fix overlapping text section failures There have been some recent reports of faddr2line failures: $ scripts/faddr2line sound/soundcore.ko sound_devnode+0x5/0x35 bad symbol size: base: 0x0000000000000000 end: 0x0000000000000000 $ ./scripts/faddr2line vmlinux.o enter_from_user_mode+0x24 bad symbol size: base: 0x0000000000005fe0 end: 0x0000000000005fe0 The problem is that faddr2line is based on 'nm', which has a major limitation: it doesn't know how to distinguish between different text sections. So if an offset exists in multiple text sections in the object, it may fail. Rewrite faddr2line to be section-aware, by basing it on readelf. Fixes: 67326666e2d4 ("scripts: add script for translating stack dump function offsets") Reported-by: Kaiwan N Billimoria Reported-by: Peter Zijlstra Signed-off-by: Josh Poimboeuf Link: https://lore.kernel.org/r/29ff99f86e3da965b6e46c1cc2d72ce6528c17c3.1652382321.git.jpoimboe@kernel.org --- scripts/faddr2line | 150 ++++++++++++++++++++++++++++++++++------------------- 1 file changed, 97 insertions(+), 53 deletions(-) (limited to 'scripts/faddr2line') diff --git a/scripts/faddr2line b/scripts/faddr2line index 6c6439f69a72..0e6268d59883 100755 --- a/scripts/faddr2line +++ b/scripts/faddr2line @@ -44,17 +44,6 @@ set -o errexit set -o nounset -READELF="${CROSS_COMPILE:-}readelf" -ADDR2LINE="${CROSS_COMPILE:-}addr2line" -SIZE="${CROSS_COMPILE:-}size" -NM="${CROSS_COMPILE:-}nm" - -command -v awk >/dev/null 2>&1 || die "awk isn't installed" -command -v ${READELF} >/dev/null 2>&1 || die "readelf isn't installed" -command -v ${ADDR2LINE} >/dev/null 2>&1 || die "addr2line isn't installed" -command -v ${SIZE} >/dev/null 2>&1 || die "size isn't installed" -command -v ${NM} >/dev/null 2>&1 || die "nm isn't installed" - usage() { echo "usage: faddr2line [--list] ..." >&2 exit 1 @@ -69,6 +58,14 @@ die() { exit 1 } +READELF="${CROSS_COMPILE:-}readelf" +ADDR2LINE="${CROSS_COMPILE:-}addr2line" +AWK="awk" + +command -v ${AWK} >/dev/null 2>&1 || die "${AWK} isn't installed" +command -v ${READELF} >/dev/null 2>&1 || die "${READELF} isn't installed" +command -v ${ADDR2LINE} >/dev/null 2>&1 || die "${ADDR2LINE} isn't installed" + # Try to figure out the source directory prefix so we can remove it from the # addr2line output. HACK ALERT: This assumes that start_kernel() is in # init/main.c! This only works for vmlinux. Otherwise it falls back to @@ -76,7 +73,7 @@ die() { find_dir_prefix() { local objfile=$1 - local start_kernel_addr=$(${READELF} -sW $objfile | awk '$8 == "start_kernel" {printf "0x%s", $2}') + local start_kernel_addr=$(${READELF} --symbols --wide $objfile | ${AWK} '$8 == "start_kernel" {printf "0x%s", $2}') [[ -z $start_kernel_addr ]] && return local file_line=$(${ADDR2LINE} -e $objfile $start_kernel_addr) @@ -97,86 +94,133 @@ __faddr2line() { local dir_prefix=$3 local print_warnings=$4 - local func=${func_addr%+*} + local sym_name=${func_addr%+*} local offset=${func_addr#*+} offset=${offset%/*} - local size= - [[ $func_addr =~ "/" ]] && size=${func_addr#*/} + local user_size= + [[ $func_addr =~ "/" ]] && user_size=${func_addr#*/} - if [[ -z $func ]] || [[ -z $offset ]] || [[ $func = $func_addr ]]; then + if [[ -z $sym_name ]] || [[ -z $offset ]] || [[ $sym_name = $func_addr ]]; then warn "bad func+offset $func_addr" DONE=1 return fi # Go through each of the object's symbols which match the func name. - # In rare cases there might be duplicates. - file_end=$(${SIZE} -Ax $objfile | awk '$1 == ".text" {print $2}') - while read symbol; do - local fields=($symbol) - local sym_base=0x${fields[0]} - local sym_type=${fields[1]} - local sym_end=${fields[3]} - - # calculate the size - local sym_size=$(($sym_end - $sym_base)) + # In rare cases there might be duplicates, in which case we print all + # matches. + while read line; do + local fields=($line) + local sym_addr=0x${fields[1]} + local sym_elf_size=${fields[2]} + local sym_sec=${fields[6]} + + # Get the section size: + local sec_size=$(${READELF} --section-headers --wide $objfile | + sed 's/\[ /\[/' | + ${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print "0x" $6; exit }') + + if [[ -z $sec_size ]]; then + warn "bad section size: section: $sym_sec" + DONE=1 + return + fi + + # Calculate the symbol size. + # + # Unfortunately we can't use the ELF size, because kallsyms + # also includes the padding bytes in its size calculation. For + # kallsyms, the size calculation is the distance between the + # symbol and the next symbol in a sorted list. + local sym_size + local cur_sym_addr + local found=0 + while read line; do + local fields=($line) + cur_sym_addr=0x${fields[1]} + local cur_sym_elf_size=${fields[2]} + local cur_sym_name=${fields[7]:-} + + if [[ $cur_sym_addr = $sym_addr ]] && + [[ $cur_sym_elf_size = $sym_elf_size ]] && + [[ $cur_sym_name = $sym_name ]]; then + found=1 + continue + fi + + if [[ $found = 1 ]]; then + sym_size=$(($cur_sym_addr - $sym_addr)) + [[ $sym_size -lt $sym_elf_size ]] && continue; + found=2 + break + fi + done < <(${READELF} --symbols --wide $objfile | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2) + + if [[ $found = 0 ]]; then + warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size" + DONE=1 + return + fi + + # If nothing was found after the symbol, assume it's the last + # symbol in the section. + [[ $found = 1 ]] && sym_size=$(($sec_size - $sym_addr)) + if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then - warn "bad symbol size: base: $sym_base end: $sym_end" + warn "bad symbol size: sym_addr: $sym_addr cur_sym_addr: $cur_sym_addr" DONE=1 return fi + sym_size=0x$(printf %x $sym_size) - # calculate the address - local addr=$(($sym_base + $offset)) + # Calculate the section address from user-supplied offset: + local addr=$(($sym_addr + $offset)) if [[ -z $addr ]] || [[ $addr = 0 ]]; then - warn "bad address: $sym_base + $offset" + warn "bad address: $sym_addr + $offset" DONE=1 return fi addr=0x$(printf %x $addr) - # weed out non-function symbols - if [[ $sym_type != t ]] && [[ $sym_type != T ]]; then - [[ $print_warnings = 1 ]] && - echo "skipping $func address at $addr due to non-function symbol of type '$sym_type'" - continue - fi - - # if the user provided a size, make sure it matches the symbol's size - if [[ -n $size ]] && [[ $size -ne $sym_size ]]; then + # If the user provided a size, make sure it matches the symbol's size: + if [[ -n $user_size ]] && [[ $user_size -ne $sym_size ]]; then [[ $print_warnings = 1 ]] && - echo "skipping $func address at $addr due to size mismatch ($size != $sym_size)" + echo "skipping $sym_name address at $addr due to size mismatch ($user_size != $sym_size)" continue; fi - # make sure the provided offset is within the symbol's range + # Make sure the provided offset is within the symbol's range: if [[ $offset -gt $sym_size ]]; then [[ $print_warnings = 1 ]] && - echo "skipping $func address at $addr due to size mismatch ($offset > $sym_size)" + echo "skipping $sym_name address at $addr due to size mismatch ($offset > $sym_size)" continue fi - # separate multiple entries with a blank line + # In case of duplicates or multiple addresses specified on the + # cmdline, separate multiple entries with a blank line: [[ $FIRST = 0 ]] && echo FIRST=0 - # pass real address to addr2line - echo "$func+$offset/$sym_size:" - local file_lines=$(${ADDR2LINE} -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;") - [[ -z $file_lines ]] && return + echo "$sym_name+$offset/$sym_size:" + # Pass section address to addr2line and strip absolute paths + # from the output: + local output=$(${ADDR2LINE} -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;") + [[ -z $output ]] && continue + + # Default output (non --list): if [[ $LIST = 0 ]]; then - echo "$file_lines" | while read -r line + echo "$output" | while read -r line do echo $line done DONE=1; - return + continue fi - # show each line with context - echo "$file_lines" | while read -r line + # For --list, show each line with its corresponding source code: + echo "$output" | while read -r line do echo echo $line @@ -184,12 +228,12 @@ __faddr2line() { n1=$[$n-5] n2=$[$n+5] f=$(echo $line | sed 's/.*at \(.\+\):.*/\1/g') - awk 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f + ${AWK} 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f done DONE=1 - done < <(${NM} -n $objfile | awk -v fn=$func -v end=$file_end '$3 == fn { found=1; line=$0; start=$1; next } found == 1 { found=0; print line, "0x"$1 } END {if (found == 1) print line, end; }') + done < <(${READELF} --symbols --wide $objfile | ${AWK} -v fn=$sym_name '$4 == "FUNC" && $8 == fn') } [[ $# -lt 2 ]] && usage -- cgit v1.2.3-70-g09d2