mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
![Carlos Llamas](/assets/img/avatar_default.png)
GNU's addr2line can have problems parsing a vmlinux built with LLVM, particularly when LTO was used. In order to decode the traces correctly this patch adds the ability to switch to LLVM's utilities readelf and addr2line. The same approach is followed by Will in [1]. Before: $ scripts/decode_stacktrace.sh vmlinux < kernel.log [17716.240635] Call trace: [17716.240646] skb_cow_data (??:?) [17716.240654] esp6_input (ld-temp.o:?) [17716.240666] xfrm_input (ld-temp.o:?) [17716.240674] xfrm6_rcv (??:?) [...] After: $ LLVM=1 scripts/decode_stacktrace.sh vmlinux < kernel.log [17716.240635] Call trace: [17716.240646] skb_cow_data (include/linux/skbuff.h:2172 net/core/skbuff.c:4503) [17716.240654] esp6_input (net/ipv6/esp6.c:977) [17716.240666] xfrm_input (net/xfrm/xfrm_input.c:659) [17716.240674] xfrm6_rcv (net/ipv6/xfrm6_input.c:172) [...] Note that one could set CROSS_COMPILE=llvm- instead to hack around this issue. However, doing so can break the decodecode routine as it will force the selection of other LLVM utilities down the line e.g. llvm-as. [1] https://lore.kernel.org/all/20230914131225.13415-3-will@kernel.org/ Link: https://lkml.kernel.org/r/20230929034836.403735-1-cmllamas@google.com Signed-off-by: Carlos Llamas <cmllamas@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Elliot Berman <quic_eberman@quicinc.com> Tested-by: Justin Stitt <justinstitt@google.com> Cc: Will Deacon <will@kernel.org> Cc: John Stultz <jstultz@google.com> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Tom Rix <trix@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
327 lines
7.6 KiB
Bash
Executable file
327 lines
7.6 KiB
Bash
Executable file
#!/bin/bash
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# SPDX-License-Identifier: GPL-2.0
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# (c) 2014, Sasha Levin <sasha.levin@oracle.com>
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#set -x
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usage() {
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echo "Usage:"
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echo " $0 -r <release> | <vmlinux> [<base path>|auto] [<modules path>]"
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}
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# Try to find a Rust demangler
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if type llvm-cxxfilt >/dev/null 2>&1 ; then
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cppfilt=llvm-cxxfilt
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elif type c++filt >/dev/null 2>&1 ; then
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cppfilt=c++filt
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cppfilt_opts=-i
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fi
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UTIL_SUFFIX=
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if [[ -z ${LLVM:-} ]]; then
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UTIL_PREFIX=${CROSS_COMPILE:-}
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else
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UTIL_PREFIX=llvm-
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if [[ ${LLVM} == */ ]]; then
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UTIL_PREFIX=${LLVM}${UTIL_PREFIX}
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elif [[ ${LLVM} == -* ]]; then
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UTIL_SUFFIX=${LLVM}
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fi
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fi
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READELF=${UTIL_PREFIX}readelf${UTIL_SUFFIX}
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ADDR2LINE=${UTIL_PREFIX}addr2line${UTIL_SUFFIX}
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if [[ $1 == "-r" ]] ; then
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vmlinux=""
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basepath="auto"
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modpath=""
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release=$2
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for fn in {,/usr/lib/debug}/boot/vmlinux-$release{,.debug} /lib/modules/$release{,/build}/vmlinux ; do
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if [ -e "$fn" ] ; then
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vmlinux=$fn
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break
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fi
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done
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if [[ $vmlinux == "" ]] ; then
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echo "ERROR! vmlinux image for release $release is not found" >&2
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usage
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exit 2
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fi
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else
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vmlinux=$1
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basepath=${2-auto}
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modpath=$3
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release=""
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debuginfod=
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# Can we use debuginfod-find?
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if type debuginfod-find >/dev/null 2>&1 ; then
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debuginfod=${1-only}
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fi
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if [[ $vmlinux == "" && -z $debuginfod ]] ; then
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echo "ERROR! vmlinux image must be specified" >&2
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usage
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exit 1
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fi
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fi
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declare aarray_support=true
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declare -A cache 2>/dev/null
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if [[ $? != 0 ]]; then
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aarray_support=false
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else
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declare -A modcache
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fi
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find_module() {
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if [[ -n $debuginfod ]] ; then
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if [[ -n $modbuildid ]] ; then
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debuginfod-find debuginfo $modbuildid && return
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fi
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# Only using debuginfod so don't try to find vmlinux module path
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if [[ $debuginfod == "only" ]] ; then
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return
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fi
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fi
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if [[ "$modpath" != "" ]] ; then
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for fn in $(find "$modpath" -name "${module//_/[-_]}.ko*") ; do
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if ${READELF} -WS "$fn" | grep -qwF .debug_line ; then
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echo $fn
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return
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fi
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done
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return 1
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fi
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modpath=$(dirname "$vmlinux")
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find_module && return
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if [[ $release == "" ]] ; then
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release=$(gdb -ex 'print init_uts_ns.name.release' -ex 'quit' -quiet -batch "$vmlinux" 2>/dev/null | sed -n 's/\$1 = "\(.*\)".*/\1/p')
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fi
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for dn in {/usr/lib/debug,}/lib/modules/$release ; do
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if [ -e "$dn" ] ; then
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modpath="$dn"
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find_module && return
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fi
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done
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modpath=""
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return 1
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}
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parse_symbol() {
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# The structure of symbol at this point is:
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# ([name]+[offset]/[total length])
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#
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# For example:
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# do_basic_setup+0x9c/0xbf
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if [[ $module == "" ]] ; then
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local objfile=$vmlinux
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elif [[ $aarray_support == true && "${modcache[$module]+isset}" == "isset" ]]; then
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local objfile=${modcache[$module]}
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else
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local objfile=$(find_module)
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if [[ $objfile == "" ]] ; then
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echo "WARNING! Modules path isn't set, but is needed to parse this symbol" >&2
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return
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fi
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if [[ $aarray_support == true ]]; then
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modcache[$module]=$objfile
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fi
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fi
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# Remove the englobing parenthesis
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symbol=${symbol#\(}
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symbol=${symbol%\)}
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# Strip segment
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local segment
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if [[ $symbol == *:* ]] ; then
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segment=${symbol%%:*}:
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symbol=${symbol#*:}
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fi
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# Strip the symbol name so that we could look it up
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local name=${symbol%+*}
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# Use 'nm vmlinux' to figure out the base address of said symbol.
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# It's actually faster to call it every time than to load it
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# all into bash.
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if [[ $aarray_support == true && "${cache[$module,$name]+isset}" == "isset" ]]; then
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local base_addr=${cache[$module,$name]}
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else
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local base_addr=$(nm "$objfile" 2>/dev/null | awk '$3 == "'$name'" && ($2 == "t" || $2 == "T") {print $1; exit}')
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if [[ $base_addr == "" ]] ; then
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# address not found
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return
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fi
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if [[ $aarray_support == true ]]; then
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cache[$module,$name]="$base_addr"
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fi
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fi
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# Let's start doing the math to get the exact address into the
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# symbol. First, strip out the symbol total length.
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local expr=${symbol%/*}
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# Now, replace the symbol name with the base address we found
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# before.
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expr=${expr/$name/0x$base_addr}
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# Evaluate it to find the actual address
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expr=$((expr))
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local address=$(printf "%x\n" "$expr")
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# Pass it to addr2line to get filename and line number
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# Could get more than one result
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if [[ $aarray_support == true && "${cache[$module,$address]+isset}" == "isset" ]]; then
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local code=${cache[$module,$address]}
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else
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local code=$(${ADDR2LINE} -i -e "$objfile" "$address" 2>/dev/null)
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if [[ $aarray_support == true ]]; then
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cache[$module,$address]=$code
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fi
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fi
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# addr2line doesn't return a proper error code if it fails, so
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# we detect it using the value it prints so that we could preserve
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# the offset/size into the function and bail out
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if [[ $code == "??:0" ]]; then
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return
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fi
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# Strip out the base of the path on each line
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code=$(while read -r line; do echo "${line#$basepath/}"; done <<< "$code")
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# In the case of inlines, move everything to same line
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code=${code//$'\n'/' '}
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# Demangle if the name looks like a Rust symbol and if
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# we got a Rust demangler
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if [[ $name =~ ^_R && $cppfilt != "" ]] ; then
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name=$("$cppfilt" "$cppfilt_opts" "$name")
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fi
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# Replace old address with pretty line numbers
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symbol="$segment$name ($code)"
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}
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debuginfod_get_vmlinux() {
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local vmlinux_buildid=${1##* }
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if [[ $vmlinux != "" ]]; then
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return
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fi
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if [[ $vmlinux_buildid =~ ^[0-9a-f]+ ]]; then
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vmlinux=$(debuginfod-find debuginfo $vmlinux_buildid)
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if [[ $? -ne 0 ]] ; then
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echo "ERROR! vmlinux image not found via debuginfod-find" >&2
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usage
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exit 2
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fi
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return
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fi
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echo "ERROR! Build ID for vmlinux not found. Try passing -r or specifying vmlinux" >&2
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usage
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exit 2
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}
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decode_code() {
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local scripts=`dirname "${BASH_SOURCE[0]}"`
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echo "$1" | $scripts/decodecode
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}
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handle_line() {
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if [[ $basepath == "auto" && $vmlinux != "" ]] ; then
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module=""
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symbol="kernel_init+0x0/0x0"
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parse_symbol
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basepath=${symbol#kernel_init (}
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basepath=${basepath%/init/main.c:*)}
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fi
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local words
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# Tokenize
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read -a words <<<"$1"
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# Remove hex numbers. Do it ourselves until it happens in the
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# kernel
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# We need to know the index of the last element before we
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# remove elements because arrays are sparse
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local last=$(( ${#words[@]} - 1 ))
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for i in "${!words[@]}"; do
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# Remove the address
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if [[ ${words[$i]} =~ \[\<([^]]+)\>\] ]]; then
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unset words[$i]
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fi
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# Format timestamps with tabs
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if [[ ${words[$i]} == \[ && ${words[$i+1]} == *\] ]]; then
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unset words[$i]
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words[$i+1]=$(printf "[%13s\n" "${words[$i+1]}")
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fi
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done
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if [[ ${words[$last]} =~ ^[0-9a-f]+\] ]]; then
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words[$last-1]="${words[$last-1]} ${words[$last]}"
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unset words[$last]
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last=$(( $last - 1 ))
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fi
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if [[ ${words[$last]} =~ \[([^]]+)\] ]]; then
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module=${words[$last]}
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module=${module#\[}
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module=${module%\]}
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modbuildid=${module#* }
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module=${module% *}
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if [[ $modbuildid == $module ]]; then
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modbuildid=
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fi
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symbol=${words[$last-1]}
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unset words[$last-1]
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else
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# The symbol is the last element, process it
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symbol=${words[$last]}
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module=
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modbuildid=
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fi
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unset words[$last]
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parse_symbol # modifies $symbol
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# Add up the line number to the symbol
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echo "${words[@]}" "$symbol $module"
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}
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while read line; do
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# Strip unexpected carriage return at end of line
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line=${line%$'\r'}
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# Let's see if we have an address in the line
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if [[ $line =~ \[\<([^]]+)\>\] ]] ||
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[[ $line =~ [^+\ ]+\+0x[0-9a-f]+/0x[0-9a-f]+ ]]; then
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# Translate address to line numbers
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handle_line "$line"
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# Is it a code line?
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elif [[ $line == *Code:* ]]; then
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decode_code "$line"
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# Is it a version line?
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elif [[ -n $debuginfod && $line =~ PID:\ [0-9]+\ Comm: ]]; then
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debuginfod_get_vmlinux "$line"
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else
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# Nothing special in this line, show it as is
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echo "$line"
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fi
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done
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