From: Richard Henderson <rth@redhat.com>
Date: Thu, 29 Nov 2012 21:11:00 +0000 (-0800)
Subject: re PR libgcc/48076 (Unsafe double checked locking in __emutls_get_address)
X-Git-Tag: releases/gcc-4.6.4~263
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ba3373f46899eedf11c19b1fda9408818b3dc831;p=thirdparty%2Fgcc.git

re PR libgcc/48076 (Unsafe double checked locking in __emutls_get_address)

PR libgcc/48076
        * emutls.c (__emutls_get_address): Add memory barrier before
        referencing emutls_key.

From-SVN: r193959
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 33a8b4f0a5ac..2eb5a7e3401b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2012-11-24  Richard Henderson  <rth@redhat.com>
+
+	PR libgcc/48076
+	* emutls.c (__emutls_get_address): Add memory barrier before
+	referencing emutls_key.
+
 2012-11-09  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* doc/install.texi (sparc64-x-solaris2): Mention MPC as well.
diff --git a/gcc/emutls.c b/gcc/emutls.c
index b7ee3bdfa7ce..fcf6eb56f9bf 100644
--- a/gcc/emutls.c
+++ b/gcc/emutls.c
@@ -151,6 +151,9 @@ __emutls_get_address (struct __emutls_object *obj)
       __gthread_mutex_unlock (&emutls_mutex);
     }
 
+  /* Do not allow emutls_key to be loaded before offset.  */
+  __sync_synchronize();
+
   struct __emutls_array *arr = __gthread_getspecific (emutls_key);
   if (__builtin_expect (arr == NULL, 0))
     {