From 937b23b5fffa59deb1dc342cc5602d387d84a762 Mon Sep 17 00:00:00 2001 From: Michal Gorny Date: Mon, 27 Nov 2017 22:23:09 +0000 Subject: [PATCH] [cmake] Pass -Wl,-z,nodelete on Linux to prevent unloading Prevent unloading shared libraries on Linux when dlclose() is called. This is necessary since command-line option parsing API relies on registering the global option instances in the option parser instance which can be loaded in a different shared library. Given that we can't reliably remove those options when a library is unloaded, the parser ends up containing dangling references. Since glibc has relatively complex library unloading rules, some of the LLVM libraries can be unloaded while others (including the Support library) stay loaded causing quite a mayhem. To reliably prevent that, just forbid unloading all libraries -- it's a very bad idea anyway. While the issue arguably happens only with BUILD_SHARED_LIBS, it may affect any library reusing llvm::cl interface. Based on patch provided Ross Hayward on https://bugs.gentoo.org/617154. Previously hit by Fedora back in Feb 2016: https://lists.freedesktop.org/archives/mesa-dev/2016-February/107242.html Differential Revision: https://reviews.llvm.org/D40459 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319105 91177308-0d34-0410-b5e6-96231b3b80d8 --- cmake/modules/HandleLLVMOptions.cmake | 8 ++++++++ unittests/Support/DynamicLibrary/CMakeLists.txt | 7 +++++++ 2 files changed, 15 insertions(+) 4.0.1 backport: removed the unittest part diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake index c5390371845..b5059a8a60e 100644 --- a/cmake/modules/HandleLLVMOptions.cmake +++ b/cmake/modules/HandleLLVMOptions.cmake @@ -151,6 +151,14 @@ if(NOT (${CMAKE_SYSTEM_NAME} MATCHES "Darwin" OR WIN32 OR CYGWIN OR set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z,defs") endif() +# Pass -Wl,-z,nodelete. This makes sure our shared libraries are not unloaded +# by dlclose(). We need that since the CLI API relies on cross-references +# between global objects which became horribly broken when one of the libraries +# is unloaded. +if(${CMAKE_SYSTEM_NAME} MATCHES "Linux") + set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z,nodelete") +endif() + function(append value) foreach(variable ${ARGN}) -- 2.15.1