[committed] Readd __tls_get_addr and __interceptor___tls_get_addr to libtsan for ABI compatibility (PR sanitizer/68824)

[Jakub Jelinek <jakub@redhat.com>]

Hi!

The fix for this PR landed upstream, so I've cherry picked it, and after
bootstrapping/regtesting it on x86_64-linux last night committed to trunk.

2016-01-19  Jakub Jelinek  <jakub@redhat.com>

	PR sanitizer/68824
	* tsan/tsan_interceptors.cc (NEED_TLS_GET_ADDR, __tls_get_addr,
	InitializeInterceptors): Cherry pick upstream r258119.

--- libsanitizer/tsan/tsan_interceptors.cc.jj	2015-11-23 18:21:10.356619453 +0100
+++ libsanitizer/tsan/tsan_interceptors.cc	2016-01-18 22:36:28.784072137 +0100
@@ -2227,6 +2227,11 @@ static void HandleRecvmsg(ThreadState *t
 // Since the interceptor only initializes memory for msan, the simplest solution
 // is to disable the interceptor in tsan (other sanitizers do not call
 // signal handlers from COMMON_INTERCEPTOR_ENTER).
+// As __tls_get_addr has been intercepted in the past, to avoid breaking
+// libtsan ABI, keep it around, but just call the real function.
+#if SANITIZER_INTERCEPT_TLS_GET_ADDR
+#define NEED_TLS_GET_ADDR
+#endif
 #undef SANITIZER_INTERCEPT_TLS_GET_ADDR
 
 #define COMMON_INTERCEPT_FUNCTION(name) INTERCEPT_FUNCTION(name)
@@ -2446,6 +2451,12 @@ static void syscall_post_fork(uptr pc, i
 
 #include "sanitizer_common/sanitizer_common_syscalls.inc"
 
+#ifdef NEED_TLS_GET_ADDR
+TSAN_INTERCEPTOR(void *, __tls_get_addr, void *arg) {
+  return REAL(__tls_get_addr)(arg);
+}
+#endif
+
 namespace __tsan {
 
 static void finalize(void *arg) {
@@ -2627,6 +2638,10 @@ void InitializeInterceptors() {
   TSAN_INTERCEPT(__cxa_atexit);
   TSAN_INTERCEPT(_exit);
 
+#ifdef NEED_TLS_GET_ADDR
+  TSAN_INTERCEPT(__tls_get_addr);
+#endif
+
 #if !SANITIZER_MAC
   // Need to setup it, because interceptors check that the function is resolved.
   // But atexit is emitted directly into the module, so can't be resolved.

	Jakub