elf, nptl: Initialize static TLS directly in ld.so

The stack list is available in ld.so since commit
1daccf403b1bd86370eb94edca794dc106d02039 ("nptl: Move stack list
variables into _rtld_global"), so it's possible to walk the stack
list directly in ld.so and perform the initialization there.

This eliminates an unprotected function pointer from _rtld_global
and reduces the libpthread initialization code.

1 files changed, 39 insertions, 0 deletions

diff --git a/elf/dl-tls.c b/elf/dl-tls.c
index f8b32b3..6baff0c 100644
--- a/elf/dl-tls.c
+++ b/elf/dl-tls.c
@@ -29,6 +29,10 @@
 #include <dl-tls.h>
 #include <ldsodefs.h>
 
+#if THREAD_GSCOPE_IN_TCB
+# include <list.h>
+#endif
+
 #define TUNABLE_NAMESPACE rtld
 #include <dl-tunables.h>
 
@@ -1005,3 +1009,38 @@ cannot create TLS data structures"));
       listp->slotinfo[idx].gen = GL(dl_tls_generation) + 1;
     }
 }
+
+#if THREAD_GSCOPE_IN_TCB
+static inline void __attribute__((always_inline))
+init_one_static_tls (struct pthread *curp, struct link_map *map)
+{
+# if TLS_TCB_AT_TP
+  void *dest = (char *) curp - map->l_tls_offset;
+# elif TLS_DTV_AT_TP
+  void *dest = (char *) curp + map->l_tls_offset + TLS_PRE_TCB_SIZE;
+# else
+#  error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
+# endif
+
+  /* Initialize the memory.  */
+  memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size),
+	  '\0', map->l_tls_blocksize - map->l_tls_initimage_size);
+}
+
+void
+_dl_init_static_tls (struct link_map *map)
+{
+  lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE);
+
+  /* Iterate over the list with system-allocated threads first.  */
+  list_t *runp;
+  list_for_each (runp, &GL (dl_stack_used))
+    init_one_static_tls (list_entry (runp, struct pthread, list), map);
+
+  /* Now the list with threads using user-allocated stacks.  */
+  list_for_each (runp, &GL (dl_stack_user))
+    init_one_static_tls (list_entry (runp, struct pthread, list), map);
+
+  lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
+}
+#endif /* THREAD_GSCOPE_IN_TCB */