Add a linker script to version LLVM symbols

Summary:
This patch adds a very simple linker script to version the lib's symbols
and thus trying to avoid crashes if an application loads two different
LLVM versions (as long as they do not share data between them).

Note that we deliberately *don't* make LLVM_5.0 depend on LLVM_4.0:
they're incompatible and the whole point of this patch is
to tell the linker that.

Avoid unexpected crashes when two LLVM versions are used in the same process.

Author: Rebecca N. Palmer <rebecca_palmer@zoho.com>
Author: Lisandro Damían Nicanor Pérez Meyer <lisandro@debian.org>
Author: Sylvestre Ledru <sylvestre@debian.org>
Bug-Debian:  https://bugs.debian.org/848368

Reviewers: beanz, rnk

Reviewed By: rnk

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D31524

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300496 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/cmake/modules/AddLLVM.cmake b/cmake/modules/AddLLVM.cmake
index 7f7608cff33d3e0c683272656fc4bd9d5fa6592f..e011bb402757e24adcab7cbb1aaa1207042c2a1d 100644 (file)
--- a/cmake/modules/AddLLVM.cmake
+++ b/cmake/modules/AddLLVM.cmake
@@ -81,8 +81,9 @@ function(add_llvm_symbol_exports target_name export_file)
     # Gold and BFD ld require a version script rather than a plain list.
     set(native_export_file "${target_name}.exports")
     # FIXME: Don't write the "local:" line on OpenBSD.
+    # in the export file, also add a linker script to version LLVM symbols (form: LLVM_N.M)
     add_custom_command(OUTPUT ${native_export_file}
-      COMMAND echo "{" > ${native_export_file}
+      COMMAND echo "LLVM_${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR} {" > ${native_export_file}
       COMMAND grep -q "[[:alnum:]]" ${export_file} && echo "  global:" >> ${native_export_file} || :
       COMMAND sed -e "s/$/;/" -e "s/^/    /" < ${export_file} >> ${native_export_file}
       COMMAND echo "  local: *;" >> ${native_export_file}

diff --git a/tools/llvm-shlib/CMakeLists.txt b/tools/llvm-shlib/CMakeLists.txt
index c68a2b0e60eae7a019543ab51da4df1cafc2e828..2781586862964f7fd1de6b0bb63cd5ba54e4f14a 100644 (file)
--- a/tools/llvm-shlib/CMakeLists.txt
+++ b/tools/llvm-shlib/CMakeLists.txt
@@ -38,8 +38,12 @@ add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB SONAME ${SOURCES})
 
 list(REMOVE_DUPLICATES LIB_NAMES)
 if(("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux") OR (MINGW) OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "FreeBSD") OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "DragonFly")) # FIXME: It should be "GNU ld for elf"
+  configure_file(
+  ${CMAKE_CURRENT_SOURCE_DIR}/simple_version_script.map.in
+  ${LLVM_LIBRARY_DIR}/tools/llvm-shlib/simple_version_script.map)
+
   # GNU ld doesn't resolve symbols in the version script.
-  set(LIB_NAMES -Wl,--whole-archive ${LIB_NAMES} -Wl,--no-whole-archive)
+  set(LIB_NAMES -Wl,--version-script,${LLVM_LIBRARY_DIR}/tools/llvm-shlib/simple_version_script.map -Wl,--whole-archive ${LIB_NAMES} -Wl,--no-whole-archive)
 elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
   set(LIB_NAMES -Wl,-all_load ${LIB_NAMES})
 endif()

diff --git a/tools/llvm-shlib/simple_version_script.map.in b/tools/llvm-shlib/simple_version_script.map.in
new file mode 100644 (file)
index 0000000..e9515fe
--- /dev/null
+++ b/tools/llvm-shlib/simple_version_script.map.in
@@ -0,0 +1 @@
+LLVM_@LLVM_VERSION_MAJOR@.@LLVM_VERSION_MINOR@ { global: *; };