From a80b3da47a40fdb6ee6ebb9892a23b11123074aa Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Thu, 24 Jun 2021 06:16:02 +0000 Subject: [PATCH] Redo the glibc compatibility issues workaround, see comment for details --- .github/workflows/build.yml | 2 +- genbindings.sh | 41 ++++++++++++++++++++++++++++++++----- 2 files changed, 37 insertions(+), 6 deletions(-) diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml index cec1f29c..cf16a652 100644 --- a/.github/workflows/build.yml +++ b/.github/workflows/build.yml @@ -15,7 +15,7 @@ jobs: run: | apt-get update apt-get -y dist-upgrade - apt-get -y install cargo libstd-rust-dev-wasm32 valgrind lld git g++ clang openjdk-11-jdk maven faketime zip unzip + apt-get -y install cargo libstd-rust-dev-wasm32 valgrind lld git g++ clang openjdk-11-jdk maven faketime zip unzip llvm - name: Checkout source code uses: actions/checkout@v2 with: diff --git a/genbindings.sh b/genbindings.sh index 7ecbdeba..9529fc08 100755 --- a/genbindings.sh +++ b/genbindings.sh @@ -84,18 +84,49 @@ if [ "$3" = "true" ]; then [ "$IS_MAC" = "false" ] && COMPILE="$COMPILE -Wl,-wrap,calloc -Wl,-wrap,realloc -Wl,-wrap,reallocarray -Wl,-wrap,malloc -Wl,-wrap,free" $COMPILE -o liblightningjni_debug$LDK_TARGET_SUFFIX.so -g -fsanitize=address -shared-libasan -rdynamic -I"$1"/lightning-c-bindings/include/ $2 src/main/jni/bindings.c "$1"/lightning-c-bindings/target/$LDK_TARGET/debug/libldk.a -lm else + LDK_LIB="$1"/lightning-c-bindings/target/$LDK_TARGET/release/libldk.a if [ "$IS_MAC" = "false" ]; then COMPILE="$COMPILE -Wl,--version-script=libcode.version -fuse-ld=lld" echo "// __cxa_thread_atexit_impl is used to more effeciently cleanup per-thread local storage by rust libstd." >> src/main/jni/bindings.c echo "// However, it is not available on glibc versions 2.17 or earlier, and rust libstd has a null-check and fallback in case it is missing." >> src/main/jni/bindings.c - echo "// Because it is weak-linked on the rust side, we can simply define it explicitly here, forcing rust to use the fallback." >> src/main/jni/bindings.c + echo "// Because it is weak-linked on the rust side, we should be able to simply define it explicitly here, forcing rust to use the fallback." >> src/main/jni/bindings.c echo "void *__cxa_thread_atexit_impl = NULL;" >> src/main/jni/bindings.c + # Note that the above is not sufficient. For some reason involving ancient dark magic and + # haunted code segments, overriding the weak symbol only impacts sites which *call* the + # symbol in question, not sites which *compare with* the symbol in question. + # This means that the NULL check in rust's libstd will always think the function is + # callable while the function which is called ends up being NULL (leading to a jmp to the + # zero page and a quick SEGFAULT). + # This issue persists not only with directly providing a symbol, but also ld.lld's -wrap + # and --defsym arguments. + # In smaller programs, it appears to be possible to work around this with -Bsymbolic and + # -nostdlib, however when applied the full-sized JNI library here it no longer works. + # After exhausting nearly every flag documented in lld, the only reliable method appears + # to be editing the LDK binary. Luckily, LLVM's tooling makes this rather easy as we can + # disassemble it into very readable code, edit it, and then reassemble it. + [ ! -f "$1"/lightning-c-bindings/target/$LDK_TARGET/release/libldk.a ] && exit 1 + if [ "$(ar t "$1"/lightning-c-bindings/target/$LDK_TARGET/release/libldk.a | grep -v "\.o$" || echo)" != "" ]; then + echo "Archive contained non-object files!" + exit 1 + fi + if [ "$(ar t "$1"/lightning-c-bindings/target/$LDK_TARGET/release/libldk.a | grep ldk.ldk.*-cgu.*.rcgu.o | wc -l)" != "1" ]; then + echo "Archive contained more than one LDK object file" + exit 1 + fi + mkdir -p tmp + rm -f tmp/* + ar x --output=tmp "$1"/lightning-c-bindings/target/$LDK_TARGET/release/libldk.a + pushd tmp + llvm-dis ldk.ldk.*-cgu.*.rcgu.o + sed -i 's/br i1 icmp eq (i8\* @__cxa_thread_atexit_impl, i8\* null)/br i1 icmp eq (i8* null, i8* null)/g' ldk.ldk.*-cgu.*.rcgu.o.ll + llvm-as ldk.ldk.*-cgu.*.rcgu.o.ll -o ./libldk.bc + ar q libldk.a *.o + popd + LDK_LIB="tmp/libldk.bc tmp/libldk.a" fi - $COMPILE -o liblightningjni_release$LDK_TARGET_SUFFIX.so -flto -O3 -I"$1"/lightning-c-bindings/include/ $2 src/main/jni/bindings.c "$1"/lightning-c-bindings/target/$LDK_TARGET/release/libldk.a + $COMPILE -o liblightningjni_release$LDK_TARGET_SUFFIX.so -flto -O3 -I"$1"/lightning-c-bindings/include/ $2 src/main/jni/bindings.c $LDK_LIB if [ "$IS_MAC" = "false" ]; then - set +e # grep exits with 1 if no lines were left, which is our success condition - GLIBC_SYMBS="$(objdump -T liblightningjni_release$LDK_TARGET_SUFFIX.so | grep GLIBC_ | grep -v "GLIBC_2\.2\." | grep -v "GLIBC_2\.3\(\.\| \)" | grep -v "GLIBC_2.\(14\|17\) ")" - set -e + GLIBC_SYMBS="$(objdump -T liblightningjni_release$LDK_TARGET_SUFFIX.so | grep GLIBC_ | grep -v "GLIBC_2\.2\." | grep -v "GLIBC_2\.3\(\.\| \)" | grep -v "GLIBC_2.\(14\|17\) " || echo)" if [ "$GLIBC_SYMBS" != "" ]; then echo "Unexpected glibc version dependency! Some users need glibc 2.17 support, symbols for newer glibcs cannot be included." echo "$GLIBC_SYMBS" -- 2.39.5