When one uses ld.gold to build gcc, the thread sanitizer doesn't work, because gold is more conservative when applying TLS relaxations than ld.bfd. In this case a missing initial-exec attribute on a declaration causes gcc to assume the general dynamic model. With ld.bfd this gets relaxed to initial exec when linking the shared library, so the missing attribute doesn't matter. But ld.gold doesn't perform this optimization and this leads to crashes on tsan instrumented binaries.
See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78294 and: https://sourceware.org/bugzilla/show_bug.cgi?id=20805 The fix is easy, just add the missing attribute. (I don't think upstream needs this fix. They don't use shared tsan lib and clang doesn't need the fix anyway.) Tested on X86_64 using ld.gold. Ok for trunk and branches? Thanks. PR sanitizer/78294 * tsan/tsan_rtl.cc: Add missing attribute. diff --git a/libsanitizer/tsan/tsan_rtl.cc b/libsanitizer/tsan/tsan_rtl.cc index 07fa165e939c..5be28ce5502e 100644 --- a/libsanitizer/tsan/tsan_rtl.cc +++ b/libsanitizer/tsan/tsan_rtl.cc @@ -43,6 +43,7 @@ extern "C" void __tsan_resume() { namespace __tsan { #if !SANITIZER_GO && !SANITIZER_MAC + __attribute__((tls_model("initial-exec"))) THREADLOCAL char cur_thread_placeholder[sizeof(ThreadState)] ALIGNED(64); #endif static char ctx_placeholder[sizeof(Context)] ALIGNED(64); -- Markus
