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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: 67326666e2 ("scripts: add script for translating stack dump function offsets")
Reported-by: Kaiwan N Billimoria <kaiwan.billimoria@gmail.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/29ff99f86e3da965b6e46c1cc2d72ce6528c17c3.1652382321.git.jpoimboe@kernel.org
This commit is contained in:
Josh Poimboeuf
parent
21e350233b
commit
1d1a0e7c51
@ -44,17 +44,6 @@
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set -o errexit
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set -o nounset
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READELF="${CROSS_COMPILE:-}readelf"
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ADDR2LINE="${CROSS_COMPILE:-}addr2line"
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SIZE="${CROSS_COMPILE:-}size"
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NM="${CROSS_COMPILE:-}nm"
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command -v awk >/dev/null 2>&1 || die "awk isn't installed"
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command -v ${READELF} >/dev/null 2>&1 || die "readelf isn't installed"
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command -v ${ADDR2LINE} >/dev/null 2>&1 || die "addr2line isn't installed"
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command -v ${SIZE} >/dev/null 2>&1 || die "size isn't installed"
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command -v ${NM} >/dev/null 2>&1 || die "nm isn't installed"
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usage() {
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echo "usage: faddr2line [--list] <object file> <func+offset> <func+offset>..." >&2
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exit 1
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@ -69,6 +58,14 @@ die() {
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exit 1
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}
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READELF="${CROSS_COMPILE:-}readelf"
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ADDR2LINE="${CROSS_COMPILE:-}addr2line"
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AWK="awk"
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command -v ${AWK} >/dev/null 2>&1 || die "${AWK} isn't installed"
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command -v ${READELF} >/dev/null 2>&1 || die "${READELF} isn't installed"
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command -v ${ADDR2LINE} >/dev/null 2>&1 || die "${ADDR2LINE} isn't installed"
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# Try to figure out the source directory prefix so we can remove it from the
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# addr2line output. HACK ALERT: This assumes that start_kernel() is in
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# init/main.c! This only works for vmlinux. Otherwise it falls back to
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@ -76,7 +73,7 @@ die() {
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find_dir_prefix() {
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local objfile=$1
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local start_kernel_addr=$(${READELF} -sW $objfile | awk '$8 == "start_kernel" {printf "0x%s", $2}')
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local start_kernel_addr=$(${READELF} --symbols --wide $objfile | ${AWK} '$8 == "start_kernel" {printf "0x%s", $2}')
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[[ -z $start_kernel_addr ]] && return
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local file_line=$(${ADDR2LINE} -e $objfile $start_kernel_addr)
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@ -97,86 +94,133 @@ __faddr2line() {
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local dir_prefix=$3
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local print_warnings=$4
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local func=${func_addr%+*}
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local sym_name=${func_addr%+*}
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local offset=${func_addr#*+}
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offset=${offset%/*}
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local size=
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[[ $func_addr =~ "/" ]] && size=${func_addr#*/}
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local user_size=
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[[ $func_addr =~ "/" ]] && user_size=${func_addr#*/}
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if [[ -z $func ]] || [[ -z $offset ]] || [[ $func = $func_addr ]]; then
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if [[ -z $sym_name ]] || [[ -z $offset ]] || [[ $sym_name = $func_addr ]]; then
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warn "bad func+offset $func_addr"
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DONE=1
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return
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fi
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# Go through each of the object's symbols which match the func name.
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# In rare cases there might be duplicates.
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file_end=$(${SIZE} -Ax $objfile | awk '$1 == ".text" {print $2}')
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while read symbol; do
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local fields=($symbol)
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local sym_base=0x${fields[0]}
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local sym_type=${fields[1]}
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local sym_end=${fields[3]}
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# In rare cases there might be duplicates, in which case we print all
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# matches.
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while read line; do
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local fields=($line)
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local sym_addr=0x${fields[1]}
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local sym_elf_size=${fields[2]}
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local sym_sec=${fields[6]}
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# calculate the size
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local sym_size=$(($sym_end - $sym_base))
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if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
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warn "bad symbol size: base: $sym_base end: $sym_end"
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# Get the section size:
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local sec_size=$(${READELF} --section-headers --wide $objfile |
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sed 's/\[ /\[/' |
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${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print "0x" $6; exit }')
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if [[ -z $sec_size ]]; then
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warn "bad section size: section: $sym_sec"
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DONE=1
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return
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fi
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# Calculate the symbol size.
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#
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# Unfortunately we can't use the ELF size, because kallsyms
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# also includes the padding bytes in its size calculation. For
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# kallsyms, the size calculation is the distance between the
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# symbol and the next symbol in a sorted list.
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local sym_size
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local cur_sym_addr
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local found=0
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while read line; do
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local fields=($line)
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cur_sym_addr=0x${fields[1]}
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local cur_sym_elf_size=${fields[2]}
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local cur_sym_name=${fields[7]:-}
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if [[ $cur_sym_addr = $sym_addr ]] &&
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[[ $cur_sym_elf_size = $sym_elf_size ]] &&
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[[ $cur_sym_name = $sym_name ]]; then
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found=1
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continue
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fi
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if [[ $found = 1 ]]; then
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sym_size=$(($cur_sym_addr - $sym_addr))
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[[ $sym_size -lt $sym_elf_size ]] && continue;
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found=2
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break
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fi
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done < <(${READELF} --symbols --wide $objfile | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2)
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if [[ $found = 0 ]]; then
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warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size"
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DONE=1
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return
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fi
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# If nothing was found after the symbol, assume it's the last
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# symbol in the section.
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[[ $found = 1 ]] && sym_size=$(($sec_size - $sym_addr))
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if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
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warn "bad symbol size: sym_addr: $sym_addr cur_sym_addr: $cur_sym_addr"
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DONE=1
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return
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fi
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sym_size=0x$(printf %x $sym_size)
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# calculate the address
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local addr=$(($sym_base + $offset))
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# Calculate the section address from user-supplied offset:
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local addr=$(($sym_addr + $offset))
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if [[ -z $addr ]] || [[ $addr = 0 ]]; then
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warn "bad address: $sym_base + $offset"
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warn "bad address: $sym_addr + $offset"
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DONE=1
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return
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fi
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addr=0x$(printf %x $addr)
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# weed out non-function symbols
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if [[ $sym_type != t ]] && [[ $sym_type != T ]]; then
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# If the user provided a size, make sure it matches the symbol's size:
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if [[ -n $user_size ]] && [[ $user_size -ne $sym_size ]]; then
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[[ $print_warnings = 1 ]] &&
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echo "skipping $func address at $addr due to non-function symbol of type '$sym_type'"
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continue
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fi
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# if the user provided a size, make sure it matches the symbol's size
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if [[ -n $size ]] && [[ $size -ne $sym_size ]]; then
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[[ $print_warnings = 1 ]] &&
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echo "skipping $func address at $addr due to size mismatch ($size != $sym_size)"
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echo "skipping $sym_name address at $addr due to size mismatch ($user_size != $sym_size)"
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continue;
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fi
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# make sure the provided offset is within the symbol's range
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# Make sure the provided offset is within the symbol's range:
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if [[ $offset -gt $sym_size ]]; then
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[[ $print_warnings = 1 ]] &&
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echo "skipping $func address at $addr due to size mismatch ($offset > $sym_size)"
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echo "skipping $sym_name address at $addr due to size mismatch ($offset > $sym_size)"
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continue
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fi
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# separate multiple entries with a blank line
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# In case of duplicates or multiple addresses specified on the
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# cmdline, separate multiple entries with a blank line:
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[[ $FIRST = 0 ]] && echo
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FIRST=0
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# pass real address to addr2line
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echo "$func+$offset/$sym_size:"
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local file_lines=$(${ADDR2LINE} -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;")
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[[ -z $file_lines ]] && return
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echo "$sym_name+$offset/$sym_size:"
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# Pass section address to addr2line and strip absolute paths
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# from the output:
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local output=$(${ADDR2LINE} -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;")
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[[ -z $output ]] && continue
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# Default output (non --list):
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if [[ $LIST = 0 ]]; then
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echo "$file_lines" | while read -r line
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echo "$output" | while read -r line
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do
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echo $line
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done
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DONE=1;
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return
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continue
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fi
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# show each line with context
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echo "$file_lines" | while read -r line
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# For --list, show each line with its corresponding source code:
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echo "$output" | while read -r line
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do
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echo
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echo $line
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@ -184,12 +228,12 @@ __faddr2line() {
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n1=$[$n-5]
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n2=$[$n+5]
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f=$(echo $line | sed 's/.*at \(.\+\):.*/\1/g')
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awk 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f
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${AWK} 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f
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done
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DONE=1
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done < <(${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"$1 } END {if (found == 1) print line, end; }')
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done < <(${READELF} --symbols --wide $objfile | ${AWK} -v fn=$sym_name '$4 == "FUNC" && $8 == fn')
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}
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[[ $# -lt 2 ]] && usage
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