The patch titled Subject: scripts/decode_stacktrace.sh: optionally use LLVM utilities has been added to the -mm mm-hotfixes-unstable branch. Its filename is scripts-decode_stacktracesh-optionally-use-llvm-utilities.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Carlos Llamas cmllamas@google.com Subject: scripts/decode_stacktrace.sh: optionally use LLVM utilities Date: Fri, 29 Sep 2023 03:48:17 +0000

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 ---

scripts/decode_stacktrace.sh | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-)

--- a/scripts/decode_stacktrace.sh~scripts-decode_stacktracesh-optionally-use-llvm-utilities +++ a/scripts/decode_stacktrace.sh @@ -16,6 +16,21 @@ elif type c++filt >/dev/null 2>&1 ; then cppfilt_opts=-i fi

+UTIL_SUFFIX= +if [[ -z ${LLVM:-} ]]; then + UTIL_PREFIX=${CROSS_COMPILE:-} +else + UTIL_PREFIX=llvm- + if [[ ${LLVM} == */ ]]; then + UTIL_PREFIX=${LLVM}${UTIL_PREFIX} + elif [[ ${LLVM} == -* ]]; then + UTIL_SUFFIX=${LLVM} + fi +fi + +READELF=${UTIL_PREFIX}readelf${UTIL_SUFFIX} +ADDR2LINE=${UTIL_PREFIX}addr2line${UTIL_SUFFIX} + if [[ $1 == "-r" ]] ; then vmlinux="" basepath="auto" @@ -75,7 +90,7 @@ find_module() {

if [[ "$modpath" != "" ]] ; then for fn in $(find "$modpath" -name "${module//_/[-_]}.ko*") ; do - if readelf -WS "$fn" | grep -qwF .debug_line ; then + if ${READELF} -WS "$fn" | grep -qwF .debug_line ; then echo $fn return fi @@ -169,7 +184,7 @@ parse_symbol() { if [[ $aarray_support == true && "${cache[$module,$address]+isset}" == "isset" ]]; then local code=${cache[$module,$address]} else - local code=$(${CROSS_COMPILE}addr2line -i -e "$objfile" "$address" 2>/dev/null) + local code=$(${ADDR2LINE} -i -e "$objfile" "$address" 2>/dev/null) if [[ $aarray_support == true ]]; then cache[$module,$address]=$code fi _

Patches currently in -mm which might be from cmllamas@google.com are

scripts-decode_stacktracesh-optionally-use-llvm-utilities.patch