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Fix PR78294 - thread sanitizer broken when using ld.gold

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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.

  PR sanitizer/78294
  * tsan/tsan_rtl.cc: Add missing attribute.

From-SVN: r242480
This commit is contained in:
Markus Trippelsdorf 2016-11-16 11:21:42 +00:00 • committed by Markus Trippelsdorf
parent 949cc52d0c
commit 8c32ae0e6d
2 changed files with 6 additions and 0 deletions
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5
libsanitizer/ChangeLog
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@ -1,3 +1,8 @@
2016-11-16 Markus Trippelsdorf <markus@trippelsdorf.de>
PR sanitizer/78294
* tsan/tsan_rtl.cc: Add missing attribute.
2016-11-16 Maxim Ostapenko <m.ostapenko@samsung.com>
* LOCAL_PATCHES: New file.

1
libsanitizer/tsan/tsan_rtl.cc
View file

@ -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);