elf: Introduce __tls_pre_init_tp

This is an early variant of __tls_init_tp, primarily for initializing
thread-related elements of _rtld_global/GL.

Some existing initialization code not needed for NPTL is moved into
the generic version of this function.

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

csu/libc-tls.c

@@ -114,6 +114,8 @@ __libc_setup_tls (void)
 
   struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
 
+  __tls_pre_init_tp ();
+
   /* Look through the TLS segment if there is any.  */
   if (_dl_phdr != NULL)
     for (phdr = _dl_phdr; phdr < &_dl_phdr[_dl_phnum]; ++phdr)

elf/dl-mutex.c

@@ -16,4 +16,4 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-/* The generic version initialization happpens in dl_main.  */
+/* Initialization happens in __tls_pre_init_tp in dl-tls_init_tp.c.  */

elf/dl-tls_init_tp.c

@@ -18,6 +18,35 @@
 
 #include <ldsodefs.h>
 
+#if defined SHARED && defined _LIBC_REENTRANT \
+    && defined __rtld_lock_default_lock_recursive
+static void
+rtld_lock_default_lock_recursive (void *lock)
+{
+  __rtld_lock_default_lock_recursive (lock);
+}
+
+static void
+rtld_lock_default_unlock_recursive (void *lock)
+{
+  __rtld_lock_default_unlock_recursive (lock);
+}
+#endif
+
+void
+__tls_pre_init_tp (void)
+{
+#if !THREAD_GSCOPE_IN_TCB
+  GL(dl_init_static_tls) = &_dl_nothread_init_static_tls;
+#endif
+
+#if defined SHARED && defined _LIBC_REENTRANT \
+    && defined __rtld_lock_default_lock_recursive
+  GL(dl_rtld_lock_recursive) = rtld_lock_default_lock_recursive;
+  GL(dl_rtld_unlock_recursive) = rtld_lock_default_unlock_recursive;
+#endif
+}
+
 void
 __tls_init_tp (void)
 {

elf/rtld.c

@@ -843,30 +843,6 @@ ERROR: ld.so: object '%s' from %s cannot be preloaded (%s): ignored.\n",
   return 0;
 }
 
-#if defined SHARED && defined _LIBC_REENTRANT \
-    && defined __rtld_lock_default_lock_recursive
-static void
-rtld_lock_default_lock_recursive (void *lock)
-{
-  __rtld_lock_default_lock_recursive (lock);
-}
-
-static void
-rtld_lock_default_unlock_recursive (void *lock)
-{
-  __rtld_lock_default_unlock_recursive (lock);
-}
-#endif
-#if PTHREAD_IN_LIBC
-/* Dummy implementation.  See __rtld_mutex_init.  */
-static int
-rtld_mutex_dummy (pthread_mutex_t *lock)
-{
-  return 0;
-}
-#endif
-
-
 static void
 security_init (void)
 {
@@ -1147,19 +1123,7 @@ dl_main (const ElfW(Phdr) *phdr,
   struct dl_main_state state;
   dl_main_state_init (&state);
 
-#if !THREAD_GSCOPE_IN_TCB
-  GL(dl_init_static_tls) = &_dl_nothread_init_static_tls;
-#endif
-
-#if defined SHARED && defined _LIBC_REENTRANT \
-    && defined __rtld_lock_default_lock_recursive
-  GL(dl_rtld_lock_recursive) = rtld_lock_default_lock_recursive;
-  GL(dl_rtld_unlock_recursive) = rtld_lock_default_unlock_recursive;
-#endif
-#if PTHREAD_IN_LIBC
-  ___rtld_mutex_lock = rtld_mutex_dummy;
-  ___rtld_mutex_unlock = rtld_mutex_dummy;
-#endif
+  __tls_pre_init_tp ();
 
   /* The explicit initialization here is cheaper than processing the reloc
      in the _rtld_local definition's initializer.  */

sysdeps/generic/ldsodefs.h

@@ -1165,6 +1165,10 @@ 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 very early from dl_main to set up TLS and
+   other thread-related data structures.  */
+void __tls_pre_init_tp (void) 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.  */

sysdeps/nptl/dl-tls_init_tp.c

@@ -27,12 +27,33 @@ bool __nptl_set_robust_list_avail __attribute__ ((nocommon));
 rtld_hidden_data_def (__nptl_set_robust_list_avail)
 #endif
 
+#ifdef SHARED
+/* Dummy implementation.  See __rtld_mutex_init.  */
+static int
+rtld_mutex_dummy (pthread_mutex_t *lock)
+{
+  return 0;
+}
+#endif
+
+void
+__tls_pre_init_tp (void)
+{
+  /* The list data structures are not consistent until
+     initialized.  */
+  INIT_LIST_HEAD (&GL (dl_stack_used));
+  INIT_LIST_HEAD (&GL (dl_stack_user));
+
+#ifdef SHARED
+  ___rtld_mutex_lock = rtld_mutex_dummy;
+  ___rtld_mutex_unlock = rtld_mutex_dummy;
+#endif
+}
+
 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));
 
    /* Early initialization of the TCB.   */