* I thought I recognized this issue, and started searching the mail archive. Seems the same question was asked last year by ... you. :-) Yeah I looked into msan some time ago and wanted to look into it again now .
* I don't understand how the msan internal functions are supposed to work, if there is no library to link to. Are they added by the compiler? I think so ! When I build a simple (working) example with msan (clang++ -fsanitize=memory in complie and link step, no libs added), I get a LOT of msan symbols in the resulting binary : nm msan_umr | grep _msan | more 00000000000221a0 t _GLOBAL__sub_I_msan_chained_origin_depot.cpp 0000000000057520 T __msan_allocated_memory 000000000004c5c0 T __msan_chain_origin 000000000004c2b0 T __msan_check_mem_is_initialized 0000000000093200 T __msan_clear_and_unpoison 000000000004c020 T __msan_clear_on_return 0000000000057600 T __msan_copy_shadow 000000000004cb50 W __msan_default_options 000000000004c150 T __msan_dump_shadow 000000000004ca60 T __msan_finish_switch_fiber 000000000004c3c0 T __msan_get_origin 000000000004ade0 T __msan_get_track_origins 000000000004c710 T __msan_get_umr_origin .... * Maybe you can try patching out -fvisibility=hidden from the compile command line to see if that makes any difference. Sounds like a good idea to start with, I will try this! Seems the visibility stuff plays a role here. Best regards, Matthias From: Magnus Ihse Bursie <magnus.ihse.bur...@oracle.com> Sent: Monday, 28 April 2025 22:06 To: Baesken, Matthias <matthias.baes...@sap.com>; build-dev@openjdk.org Subject: Re: clang Memory sanitizer (msan) and OpenJDK I thought I recognized this issue, and started searching the mail archive. Seems the same question was asked last year by ... you. :-) https://mail.openjdk.org/pipermail/build-dev/2024-August/046011.html I guess nobody still has a simple answer to give you. I don't understand how the msan internal functions are supposed to work, if there is no library to link to. Are they added by the compiler? Maybe you can try patching out -fvisibility=hidden from the compile command line to see if that makes any difference. /Magnus On 2025-04-25 16:28, Baesken, Matthias wrote: Hi, Memory sanitizer https://clang.llvm.org/docs/MemorySanitizer.html is supported with the clang toolchain (e.g. on Linux) ; “MemorySanitizer is a detector of uninitialized memory use” . For small examples it is rather easy to use, you just compile and link with -fsanitize=memory (and for better results maybe additionally -fno-omit-frame-pointer ) . So I gave it a try with OpenJDK too and added -fsanitize=memory to the C/CXX and LD flags (--with-extra-cflags=-fsanitize=memory --with-extra-cxxflags=-fsanitize=memory --with-extra-ldflags=-fsanitize=memory ). As far as compiling single compilation units this seems to be okay . But when it comes to executing the new generated binaries in the build process we unfortunately get lookup errors / undefined symbols : /builddir/jdk/bin/javac: symbol lookup error: /builddir/jdk/bin/../lib/libjli.so: undefined symbol: __msan_param_tls Is there something special in our OpenJDK build that causes trouble here ? Here I found an somewhat similar looking issue : https://groups.google.com/g/memory-sanitizer/c/xV3OZZCiL9A where re-exporting symbols is mentioned - is this maybe something that hits us in OpenJDK too ? For address sanitizer, we set -shared-libasan in the OpenJDK : https://github.com/openjdk/jdk/blob/5c067232bf21aaca2b7addd2a862e15a8696ffb8/make/autoconf/jdk-options.m4#L449 ASAN_LDFLAGS="$ASAN_LDFLAGS -shared-libasan" But I could not find something similar for msan . (btw. I use clang 15.0.7 on SUSE Linux x86_64 in case this matters) Best regards, Matthias
