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>

csu/libc-tls.c

@@ -24,7 +24,6 @@
 #include <stdio.h>
 #include <sys/param.h>
 #include <array_length.h>
-#include <list.h>
 
 #ifdef SHARED
  #error makefile bug, this file is for static only
@@ -193,12 +192,7 @@ __libc_setup_tls (void)
 #endif
   if (__builtin_expect (lossage != NULL, 0))
     _startup_fatal (lossage);
-
+  __tls_init_tp ();
-#if THREAD_GSCOPE_IN_TCB
-  INIT_LIST_HEAD (&_dl_stack_used);
-  INIT_LIST_HEAD (&_dl_stack_user);
-  list_add (&THREAD_SELF->list, &_dl_stack_user);
-#endif
 
   /* Update the executable's link map with enough information to make
      the TLS routines happy.  */

elf/Makefile

@@ -35,7 +35,7 @@ dl-routines	= $(addprefix dl-,load lookup object reloc deps \
 				  execstack open close trampoline \
 				  exception sort-maps lookup-direct \
 				  call-libc-early-init write \
-				  thread_gscope_wait)
+				  thread_gscope_wait tls_init_tp)
 ifeq (yes,$(use-ldconfig))
 dl-routines += dl-cache
 endif

elf/dl-tls_init_tp.c

@@ -0,0 +1,24 @@
+/* Completion of TCB initialization after TLS_INIT_TP.  Generic version.
+   Copyright (C) 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>
+
+void
+__tls_init_tp (void)
+{
+}

elf/rtld.c

@@ -48,7 +48,6 @@
 #include <array_length.h>
 #include <libc-early-init.h>
 #include <dl-main.h>
-#include <list.h>
 #include <gnu/lib-names.h>
 #include <dl-tunables.h>
 
@@ -807,9 +806,7 @@ cannot allocate TLS data structures for initial thread\n");
   const char *lossage = TLS_INIT_TP (tcbp);
   if (__glibc_unlikely (lossage != NULL))
     _dl_fatal_printf ("cannot set up thread-local storage: %s\n", lossage);
-#if THREAD_GSCOPE_IN_TCB
+  __tls_init_tp ();
-  list_add (&THREAD_SELF->list, &GL (dl_stack_user));
-#endif
   tls_init_tp_called = true;
 
   return tcbp;
@@ -1150,11 +1147,6 @@ dl_main (const ElfW(Phdr) *phdr,
   GL(dl_rtld_unlock_recursive) = rtld_lock_default_unlock_recursive;
 #endif
 
-#if THREAD_GSCOPE_IN_TCB
-  INIT_LIST_HEAD (&GL (dl_stack_used));
-  INIT_LIST_HEAD (&GL (dl_stack_user));
-#endif
-
   /* The explicit initialization here is cheaper than processing the reloc
      in the _rtld_local definition's initializer.  */
   GL(dl_make_stack_executable_hook) = &_dl_make_stack_executable;
@@ -2454,9 +2446,7 @@ dl_main (const ElfW(Phdr) *phdr,
       if (__glibc_unlikely (lossage != NULL))
 	_dl_fatal_printf ("cannot set up thread-local storage: %s\n",
 			  lossage);
-#if THREAD_GSCOPE_IN_TCB
+      __tls_init_tp ();
-      list_add (&THREAD_SELF->list, &GL (dl_stack_user));
-#endif
     }
 
   /* Make sure no new search directories have been added.  */

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

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));
+}