Async-signal safe TLS.

ChangeLog:

2014-01-03  Andrew Hunter  <ahh@google.com>

	* elf/dl-open.c (): New comment.
	* elf/dl-reloc.c (_dl_try_allocate_static_tls): Use
	atomic_compare_and_exchange_bool_acq
	(_dl_allocate_static_tls): Block signals.
	* elf/dl-tls.c (allocate_and_init): Return void.
	(_dl_update_slotinfo): Block signals, use atomic update.

nptl/ChangeLog:

2014-01-03  Andrew Hunter  <ahh@google.com>

	* nptl/Makefile (tst-tls7): New test.
	* nptl/tst-tls7.c: New file.
	* nptl/tst-tls7mod.c: New file.
	* nptl/allocatestack.c (init_one_static_tls): Use atomic barrier.

1 files changed, 43 insertions, 0 deletions

diff --git a/nptl/tst-tls7mod.c b/nptl/tst-tls7mod.c
new file mode 100644
index 0000000..aff29b9
--- /dev/null
+++ b/nptl/tst-tls7mod.c
@@ -0,0 +1,43 @@
+/* Copyright (C) 2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Dynamic module with TLS to be accessed by a signal handler to check safety
+   of that mode. */
+
+#include <semaphore.h>
+#include <signal.h>
+#include <unistd.h>
+
+/* This is an unlikely value to see in incorrectly initialized TLS
+   block -- make sure we're initialized properly. */
+static __thread intptr_t tls_data = 0xdeadbeef;
+
+void
+action (int signo, siginfo_t *info, void *ignored)
+{
+  sem_t *sem = info->si_value.sival_ptr;
+  if (tls_data != 0xdeadbeef)
+    {
+      write (STDOUT_FILENO, "wrong TLS value\n", 17);
+      _exit (1);
+    }
+
+  /* arbitrary choice, just write something unique-ish. */
+  tls_data = (intptr_t) info;
+
+  sem_post (sem);
+}