[PATCH 2/4] Add generic <thread_pointer.h>

[Florian Weimer]

It uses the GCC built-in.  Based on the exixsting THREAD_SELF
definition, this version is suitable for:

  aarch64
  alpha
  arc
  arm
  s390
  s390x

It also builds on all mips and sh variants with current GCC.  We can
use it there as well for now, and add custom <thread_pointer.h>
headers once if it proves necessary.
---
 sysdeps/generic/thread_pointer.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 sysdeps/generic/thread_pointer.h

diff --git a/sysdeps/generic/thread_pointer.h b/sysdeps/generic/thread_pointer.h
new file mode 100644
index 0000000000..7c2faf0218
--- /dev/null
+++ b/sysdeps/generic/thread_pointer.h
@@ -0,0 +1,28 @@
+/* __thread_pointer definition.  Generic version using GCC built-in.
+   Copyright (C) 2021-2025 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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _SYS_THREAD_POINTER_H
+#define _SYS_THREAD_POINTER_H
+
+static inline void *
+__thread_pointer (void)
+{
+  return __builtin_thread_pointer ();
+}
+
+#endif /* _SYS_THREAD_POINTER_H */
-- 
2.47.1