[Bug sanitizer/68824] [6 Regression] libtsan is missing the __interceptor___tls_get_addr symbol without bumping the soname

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68824

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Dmitry Vyukov from comment #5)
> In 3) did you mean -mstackrealign?

No, I meant -mincoming-stack-boundary=3, -mstackrealign doesn't do anything in
this case.

> 1) looks like the simplest option. Are there any downsides?

Of course, it will be a hassle for anybody who has any -fsanitize=thread linked
code around, it will no longer be possible to mix tsan instrumented code
between gcc 4.9/5 and gcc 6+, because having two different libtsan versions in
one app won't work.

Untested patch for 2) would be like:

--- libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc.jj 
2015-11-23 13:29:55.000000000 +0100
+++ libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc    
2016-01-18 11:52:47.167981314 +0100
@@ -4215,8 +4215,10 @@ INTERCEPTOR(void *, __tls_get_addr, void
   return res;
 }
 #else
+#ifndef INIT_TLS_GET_ADDR
 #define INIT_TLS_GET_ADDR
 #endif
+#endif

 #if SANITIZER_INTERCEPT_LISTXATTR
 INTERCEPTOR(SSIZE_T, listxattr, const char *path, char *list, SIZE_T size) {
--- libsanitizer/tsan/tsan_interceptors.cc.jj   2015-11-23 13:29:58.000000000
+0100
+++ libsanitizer/tsan/tsan_interceptors.cc      2016-01-18 11:54:04.792903073
+0100
@@ -2227,6 +2227,14 @@ 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 INIT_TLS_GET_ADDR COMMON_INTERCEPT_FUNCTION(__tls_get_addr)
+INTERCEPTOR(void *, __tls_get_addr, void *arg) {
+  return REAL(__tls_get_addr)(arg);
+}
+#endif
 #undef SANITIZER_INTERCEPT_TLS_GET_ADDR

 #define COMMON_INTERCEPT_FUNCTION(name) INTERCEPT_FUNCTION(name)