Messages in this thread Patch in this message | | | Date | Tue, 19 Dec 2023 00:23:18 +0000 | From | Justin Stitt <> | Subject | Re: [PATCH] scripts/decode_stacktrace.sh: optionally use LLVM utilities |
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Hi,
On Fri, Sep 29, 2023 at 03:48:17AM +0000, Carlos Llamas wrote: > 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 (??:?) > [...]
Perhaps it is due to where I am dumping the stack, but I am getting good stack traces on mainline (with a LLVM-built kernel) without this patch.
With that being said, applying this patch still has good stack traces and it makes sense if it helps others.
> > 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/ > > Cc: Will Deacon <will@kernel.org> > Cc: John Stultz <jstultz@google.com> > Cc: Masahiro Yamada <masahiroy@kernel.org> > Signed-off-by: Carlos Llamas <cmllamas@google.com>
Tested-by: Justin Stitt <justinstitt@google.com>
Note that this patch is similar: https://lore.kernel.org/all/20231215-llvm-decode-stacktrace-v1-1-201cb86f4879@quicinc.com/
> --- > scripts/decode_stacktrace.sh | 19 +++++++++++++++++-- > 1 file changed, 17 insertions(+), 2 deletions(-) > > diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh > index 564c5632e1a2..bfe5a4082d8e 100755 > --- a/scripts/decode_stacktrace.sh > +++ b/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 > -- > 2.42.0.582.g8ccd20d70d-goog >
Thanks Justin
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