From 5d10459b6b5182fcbc98240d9dace026c87a5037 Mon Sep 17 00:00:00 2001 From: Kienan Stewart Date: Mon, 5 Aug 2024 15:41:34 -0400 Subject: [PATCH] Fix: Build examples when rpath is stripped from in-build-tree libs Observed issue ============== Certain tool chains[1, 2] emit warnings or errors when building the example applications. ``` make[3]: Entering directory '/home/xxx/src/efficios/lttng/master/src/lttng-ust/doc/examples/easy-ust' CC sample.o CC tp.o CCLD sample /usr/bin/ld: warning: liblttng-ust-common.so.1, needed by ../../../src/lib/lttng-ust/.libs/liblttng-ust.so, not found (try using -rpath or -rpath-link) /usr/bin/ld: warning: liblttng-ust-tracepoint.so.1, needed by ../../../src/lib/lttng-ust/.libs/liblttng-ust.so, not found (try using -rpath or -rpath-link) /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_add_fd_to_tracker' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_urcu_after_fork_child' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_common_ctor' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_tp_init' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_tp_probe_register_queue_release' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_cancelstate_disable_pop' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_urcu_synchronize_rcu' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_urcu_register_thread' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_tp_probe_prune_release_queue' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_cancelstate_disable_push' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_urcu_before_fork' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_lock_fd_tracker' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_trace_clock' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_urcu_has_sys_membarrier' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_unlock_fd_tracker' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_tp_exit' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_get_cpu_sym' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_common_alloc_tls' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_urcu_after_fork_parent' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_delete_fd_from_tracker' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_urcu_register' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_urcu_reader' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_urcu_gp' /usr/bin/ld: ../../../src/lib/lttng-ust/.libs/liblttng-ust.so: undefined reference to `lttng_ust_tp_probe_unregister_queue_release' collect2: error: ld returned 1 exit status ``` === Reproducer === The easiest way to consistently reproduce this type of build failure is to perform the following steps: ``` ./configure make -j$(nproc) find . -iname '*.so' -exec chrpath -d {} \; make -C doc/examples clean make -j$(nproc) ``` As the examples are not built with libtool, finding the libraries to link against depends on the shared objects having an rpath. E.g. ``` $ chrpath src/lib/lttng-ust/.libs/liblttng-ust.so.1.0.0 src/lib/lttng-ust/.libs/liblttng-ust.so.1.0.0: RUNPATH=/home/xxx/src/efficios/lttng/master/src/lttng-ust/src/lib/lttng-ust-common/.libs:/home/xxx/src/efficios/lttng/master/src/lttng-ust/src/lib/lttng-ust-tracepoint/.libs:/home/xxx/src/efficios/lttng/master/usr/lib ``` The current examples build with `-Wl,-rpath` for `liblttng-ust`, but not the dependencies of `liblttng-ust` (which would normally be found via it's own rpath). If the `rpath` is stripped from `liblttng-ust.so`, or if the tool chain ignores `rpath` explicitly, then the build with fail. In the case of a yocto build environment as in GitHub#61[1], the following commands reproduced the warnings and the errors seen in the above test case. ``` git clone git://git.yoctoproject.org/poky && cd poky/ . oe-init-build-env echo "PACKAGECONFIG:pn-lttng-ust = 'examples'" >>conf/local.conf bitbake lttng-ust ``` === Solution === Explicitly add library search paths and set linker rpath-link are set for both the standard and cmake examples. Similar changes were proposed for each of those parts respectively in GitHub#61[1] and GitHub#63[2]. === Known issues === While the `rpath-link` for the second order library dependencies will allow the builds to complete, the examples will not work at runtime even when using `rpath`. From `man ld.so`, the rpaths in an executable or shared object are only considered for direct dependencies. Therefore, without setting `LD_LIBRARY_PATH` or installing the libraries test applications will fail as follows: ``` $ ./doc/examples/easy-ust/sample ./doc/examples/easy-ust/sample: error while loading shared libraries: liblttng-ust-common.so.1: cannot open shared object file: No such file or directory ``` References ========== [1]: https://github.com/lttng/lttng-ust/pull/61 [2]: https://github.com/lttng/lttng-ust/pull/63 Change-Id: I273ccddd0d0b7a1b57b9e09ddf48d8b5b41e6f8e Signed-off-by: Kienan Stewart Signed-off-by: Mathieu Desnoyers Upstream-Status: Backport [https://github.com/lttng/lttng-ust/commit/5d10459b6b5182fcbc98240d9dace026c87a5037] Signed-off-by: Bin Lan --- doc/examples/Makefile.am | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/doc/examples/Makefile.am b/doc/examples/Makefile.am index aebf63bd..79766ec0 100644 --- a/doc/examples/Makefile.am +++ b/doc/examples/Makefile.am @@ -169,7 +169,10 @@ all-local: CFLAGS='$(CFLAGS)' \ AM_CFLAGS='$(AM_CFLAGS)' \ LDFLAGS="$(LDFLAGS)" \ - AM_LDFLAGS='$(AM_LDFLAGS) -L../../../src/lib/lttng-ust/.libs -Wl,-rpath="$(PWD)/../../src/lib/lttng-ust/.libs/" -Wl,-rpath-link="$(PWD)/../../src/lib/lttng-ust/.libs/"' \ + AM_LDFLAGS='$(AM_LDFLAGS) -L../../../src/lib/lttng-ust/.libs -L../../../src/lib/lttng-ust-common/.libs -L../../../src/lib/lttng-ust-tracepoint/.libs \ + -Wl,-rpath="$(abs_top_builddir)/src/lib/lttng-ust/.libs/" \ + -Wl,-rpath-link="$(abs_top_builddir)/src/lib/lttng-ust-common/.libs/" \ + -Wl,-rpath-link="$(abs_top_builddir)/src/lib/lttng-ust-tracepoint/.libs/"' \ LTTNG_GEN_TP_PATH="$$rel_src_subdir$(top_srcdir)/tools/" \ AM_V_P="$(AM_V_P)" \ AM_V_at="$(AM_V_at)" \ @@ -222,10 +225,14 @@ all-local: CXX="$(CXX)" \ $(CMAKE) \ -DCMAKE_INCLUDE_PATH="$(abs_top_srcdir)/include;$(abs_top_builddir)/include" \ - -DCMAKE_LIBRARY_PATH="$(abs_top_builddir)/src/lib/lttng-ust/.libs" \ + -DCMAKE_LIBRARY_PATH="$(abs_top_builddir)/src/lib/lttng-ust/.libs;$(abs_top_builddir)/src/lib/lttng-ust-common/.libs;$(abs_top_builddir)/src/lib/lttng-ust-tracepoint/.libs" \ -DCMAKE_C_FLAGS="$(AM_CFLAGS) $(CPPFLAGS) $(CFLAGS)" \ -DCMAKE_CXX_FLAGS="$(AM_CXXFLAGS) $(CXXFLAGS) $(CPPFLAGS)" \ - -DCMAKE_EXE_LINKER_FLAGS="$(AM_LDFLAGS) $(LDFLAGS)" \ + -DCMAKE_EXE_LINKER_FLAGS="$(AM_LDFLAGS) $(LDFLAGS) \ + -L../../../src/lib/lttng-ust/.libs -L../../../src/lib/lttng-ust-common/.libs -L../../../src/lib/lttng-ust-tracepoint/.libs \ + -Wl,-rpath=$(abs_top_builddir)/src/lib/lttng-ust/.libs/ \ + -Wl,-rpath-link=$(abs_top_builddir)/src/lib/lttng-ust-common/.libs/ \ + -Wl,-rpath-link=$(abs_top_builddir)/src/lib/lttng-ust-tracepoint/.libs/" \ .. && \ $(MAKE) \ ) || exit 1; \ -- 2.43.0