string: Remove old TLS usage on strsignal

The per-thread state is refactored two use two strategies:

  1. The default one uses a TLS structure, which will be placed in the
     static TLS space (using __thread keyword).

  2. Linux allocates via struct pthread and access it through THREAD_*
     macros.

The default strategy has the disadvantage of increasing libc.so static
TLS consumption and thus decreasing the possible surplus used in
some scenarios (which might be mitigated by BZ#25051 fix).

It is used only on Hurd, where accessing the thread storage in the in
single thread case is not straightforward (afaiu, Hurd developers could
correct me here).

The fallback static allocation used for allocation failure is also
removed: defining its size is problematic without synchronizing with
translated messages (to avoid partial translation) and the resulting
usage is not thread-safe.

Checked on x86-64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
and s390x-linux-gnu.

Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

2 files changed, 38 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/tls-internal.c b/sysdeps/unix/sysv/linux/tls-internal.c
new file mode 100644
index 0000000000..6e25b021ab
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tls-internal.c
@@ -0,0 +1 @@
+/* Empty.  */
diff --git a/sysdeps/unix/sysv/linux/tls-internal.h b/sysdeps/unix/sysv/linux/tls-internal.h
new file mode 100644
index 0000000000..5d712abd4a
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tls-internal.h
@@ -0,0 +1,37 @@
+/* Per-thread state.  Linux version.
+   Copyright (C) 2020 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 _TLS_INTERNAL_H
+#define _TLS_INTERNAL_H 1
+
+#include <stdlib.h>
+#include <nptl/pthreadP.h>
+
+static inline struct tls_internal_t *
+__glibc_tls_internal (void)
+{
+  return &THREAD_SELF->tls_state;
+}
+
+static inline void
+__glibc_tls_internal_free (void)
+{
+  free (THREAD_SELF->tls_state.strsignal_buf);
+}
+
+#endif