[glibc] elf: Introduce __tls_pre_init_tp

[glibc] elf: Introduce __tls_pre_init_tp

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d017b0ab5a181dce4145f3a1b3b27e3341abd201

commit d017b0ab5a181dce4145f3a1b3b27e3341abd201
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon May 10 10:31:41 2021 +0200

    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>

Diff:
---
 csu/libc-tls.c                |  2 ++
 elf/dl-mutex.c                |  2 +-
 elf/dl-tls_init_tp.c          | 29 +++++++++++++++++++++++++++++
 elf/rtld.c                    | 38 +-------------------------------------
 sysdeps/generic/ldsodefs.h    |  4 ++++
 sysdeps/nptl/dl-tls_init_tp.c | 25 +++++++++++++++++++++++--
 6 files changed, 60 insertions(+), 40 deletions(-)

diff --git a/csu/libc-tls.c b/csu/libc-tls.c
index 22f8e4838d..5515204863 100644
--- a/csu/libc-tls.c
+++ b/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)
diff --git a/elf/dl-mutex.c b/elf/dl-mutex.c
index 2cd9d49c2e..ae1d8a84f0 100644
--- a/elf/dl-mutex.c
+++ b/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.  */
diff --git a/elf/dl-tls_init_tp.c b/elf/dl-tls_init_tp.c
index 728cd84c00..d84adc992c 100644
--- a/elf/dl-tls_init_tp.c
+++ b/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)
 {
diff --git a/elf/rtld.c b/elf/rtld.c
index a359167f8a..1255d5cc7d 100644
--- a/elf/rtld.c
+++ b/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.  */
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 6d590d1335..ee851ac789 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/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.  */
diff --git a/sysdeps/nptl/dl-tls_init_tp.c b/sysdeps/nptl/dl-tls_init_tp.c
index 05d2b6cfcc..cb29222727 100644
--- a/sysdeps/nptl/dl-tls_init_tp.c
+++ b/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_init_tp (void)
+__tls_pre_init_tp (void)
 {
-  /* Set up thread stack list management.  */
+  /* 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.  */
   list_add (&THREAD_SELF->list, &GL (dl_stack_user));
 
    /* Early initialization of the TCB.   */