Fix alignment of TLS variables for tls variant TLS_TCB_AT_TP [BZ #23403]

The alignment of TLS variables is wrong if accessed from within a thread
for architectures with tls variant TLS_TCB_AT_TP.
For the main thread the static tls data is properly aligned.
For other threads the alignment depends on the alignment of the thread
pointer as the static tls data is located relative to this pointer.

This patch adds this alignment for TLS_TCB_AT_TP variants in the same way
as it is already done for TLS_DTV_AT_TP. The thread pointer is also already
properly aligned if the user provides its own stack for the new thread.

This patch extends the testcase nptl/tst-tls1.c in order to check the
alignment of the tls variables and it adds a pthread_create invocation
with a user provided stack.
The test itself is migrated from test-skeleton.c to test-driver.c
and the missing support functions xpthread_attr_setstack and xposix_memalign
are added.

ChangeLog:

	[BZ #23403]
	* nptl/allocatestack.c (allocate_stack): Align pointer pd for
	TLS_TCB_AT_TP tls variant.
	* nptl/tst-tls1.c: Migrate to support/test-driver.c.
	Add alignment checks.
	* support/Makefile (libsupport-routines): Add xposix_memalign and
	xpthread_setstack.
	* support/support.h: Add xposix_memalign.
	* support/xthread.h: Add xpthread_attr_setstack.
	* support/xposix_memalign.c: New File.
	* support/xpthread_attr_setstack.c: Likewise.

5 files changed, 66 insertions, 0 deletions

diff --git a/support/Makefile b/support/Makefile
index c15b93647c..9ff0ec3fff 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -99,10 +99,12 @@ libsupport-routines = \
   xopen \
   xpipe \
   xpoll \
+  xposix_memalign \
   xpthread_attr_destroy \
   xpthread_attr_init \
   xpthread_attr_setdetachstate \
   xpthread_attr_setguardsize \
+  xpthread_attr_setstack \
   xpthread_attr_setstacksize \
   xpthread_barrier_destroy \
   xpthread_barrier_init \
diff --git a/support/support.h b/support/support.h
index 119495e5a9..97fef2cd23 100644
--- a/support/support.h
+++ b/support/support.h
@@ -86,6 +86,7 @@ int support_descriptor_supports_holes (int fd);
 void *xmalloc (size_t) __attribute__ ((malloc));
 void *xcalloc (size_t n, size_t s) __attribute__ ((malloc));
 void *xrealloc (void *p, size_t n);
+void *xposix_memalign (size_t alignment, size_t n);
 char *xasprintf (const char *format, ...)
   __attribute__ ((format (printf, 1, 2), malloc));
 char *xstrdup (const char *);
diff --git a/support/xposix_memalign.c b/support/xposix_memalign.c
new file mode 100644
index 0000000000..5501a0846a
--- /dev/null
+++ b/support/xposix_memalign.c
@@ -0,0 +1,35 @@
+/* Error-checking wrapper for posix_memalign.
+   Copyright (C) 2019 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/>.  */
+
+#include <support/support.h>
+#include <stdlib.h>
+#include <errno.h>
+
+void *
+xposix_memalign (size_t alignment, size_t n)
+{
+  void *p = NULL;
+
+  int ret = posix_memalign (&p, alignment, n);
+  if (ret)
+    {
+      errno = ret;
+      oom_error ("posix_memalign", n);
+    }
+  return p;
+}
diff --git a/support/xpthread_attr_setstack.c b/support/xpthread_attr_setstack.c
new file mode 100644
index 0000000000..c3772e240b
--- /dev/null
+++ b/support/xpthread_attr_setstack.c
@@ -0,0 +1,26 @@
+/* pthread_attr_setstack with error checking.
+   Copyright (C) 2019 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/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_attr_setstack (pthread_attr_t *attr, void *stackaddr, size_t stacksize)
+{
+  xpthread_check_return ("pthread_attr_setstack",
+			 pthread_attr_setstack (attr, stackaddr, stacksize));
+}
diff --git a/support/xthread.h b/support/xthread.h
index 9fe1f68b3b..5204f78ed2 100644
--- a/support/xthread.h
+++ b/support/xthread.h
@@ -68,6 +68,8 @@ void xpthread_attr_destroy (pthread_attr_t *attr);
 void xpthread_attr_init (pthread_attr_t *attr);
 void xpthread_attr_setdetachstate (pthread_attr_t *attr,
 				   int detachstate);
+void xpthread_attr_setstack (pthread_attr_t *attr, void *stackaddr,
+			     size_t stacksize);
 void xpthread_attr_setstacksize (pthread_attr_t *attr,
 				 size_t stacksize);
 void xpthread_attr_setguardsize (pthread_attr_t *attr,