elf: Introduce __tls_init_tp for second-phase TCB initialization

TLS_INIT_TP is processor-specific, so it is not a good place to
put thread library initialization code (it would have to be repeated
for all CPUs).  Introduce __tls_init_tp as a separate function,
to be called immediately after TLS_INIT_TP.  Move the existing
stack list setup code for NPTL to this function.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

2 files changed, 35 insertions, 0 deletions

diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index dfc117a445..67c6686015 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -1163,6 +1163,11 @@ extern void _dl_determine_tlsoffset (void) attribute_hidden;
    number of audit modules are loaded.  */
 void _dl_tls_static_surplus_init (size_t naudit) attribute_hidden;
 
+/* This function is called after processor-specific initialization of
+   the TCB and thread pointer via TLS_INIT_TP, to complete very early
+   initialization of the thread library.  */
+void __tls_init_tp (void) attribute_hidden;
+
 #ifndef SHARED
 /* Set up the TCB for statically linked applications.  This is called
    early during startup because we always use TLS (for errno and the
diff --git a/sysdeps/nptl/dl-tls_init_tp.c b/sysdeps/nptl/dl-tls_init_tp.c
new file mode 100644
index 0000000000..8983808233
--- /dev/null
+++ b/sysdeps/nptl/dl-tls_init_tp.c
@@ -0,0 +1,30 @@
+/* Completion of TCB initialization after TLS_INIT_TP.  NPTL version.
+   Copyright (C) 2020-2021 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/>.  */
+
+#include <ldsodefs.h>
+#include <list.h>
+#include <tls.h>
+
+void
+__tls_init_tp (void)
+{
+  /* Set up thread stack list management.  */
+  INIT_LIST_HEAD (&GL (dl_stack_used));
+  INIT_LIST_HEAD (&GL (dl_stack_user));
+  list_add (&THREAD_SELF->list, &GL (dl_stack_user));
+}