[patch] Do update_slotinfo after add_to_slotinfo

gentoo353224a.patch (text/plain), 2.18 KB, created by Martin von Gagern on 2011-01-30 15:03:51 UTC

Fix a bug in tls initialization which caused __tls_get_addr to return NULL.

We need to postpone all calls to _dl_update_slotinfo until after
_dl_add_to_slotinfo is complete. This is because _dl_update_slotinfo
will modify the generation of the DTV to match that of the new
slot. We cannot allow this to happen until all slots of the generation
have been added.

2010-01-30 Martin von Gagern

References:
https://github.com/cschwan/sage-on-gentoo/issues/#issue/40
https://bugs.gentoo.org/353224

Index: glibc-2.12.2/elf/dl-open.c
===================================================================
--- glibc-2.12.2.orig/elf/dl-open.c
+++ glibc-2.12.2/elf/dl-open.c
@@ -346,7 +346,7 @@ dl_open_worker (void *a)
 
   /* If the file is not loaded now as a dependency, add the search
      list of the newly loaded object to the scope.  */
-  bool any_tls = false;
+  bool any_tls = false, any_static_tls = false;
   for (unsigned int i = 0; i < new->l_searchlist.r_nlist; ++i)
     {
       struct link_map *imap = new->l_searchlist.r_list[i];
@@ -426,6 +426,25 @@ dl_open_worker (void *a)
 	  _dl_add_to_slotinfo (imap);
 
 	  if (imap->l_need_tls_init)
+	    any_static_tls = true;
+
+	  /* We have to bump the generation counter.  */
+	  any_tls = true;
+	}
+    }
+
+  /* We need a second pass for static tls data, because _dl_update_slotinfo
+     must not be run while calls to _dl_add_to_slotinfo are still pending. */
+  if (__builtin_expect (any_static_tls, 0))
+    {
+      for (unsigned int i = 0; i < new->l_searchlist.r_nlist; ++i)
+	{
+	  struct link_map *imap = new->l_searchlist.r_list[i];
+	  if (__builtin_expect (imap->l_need_tls_init, 0)
+	      /* The following two can likely be dropped, but let's be extra
+		 safe and copy all the conditions for now. */
+	      && ! imap->l_init_called
+	      && __builtin_expect (imap->l_tls_blocksize > 0, 0))
 	    {
 	      /* For static TLS we have to allocate the memory here
 		 and now.  This includes allocating memory in the DTV.
@@ -449,9 +468,6 @@ cannot load any more object with static
 	      GL(dl_init_static_tls) (imap);
 	      assert (imap->l_need_tls_init == 0);
 	    }
-
-	  /* We have to bump the generation counter.  */
-	  any_tls = true;
 	}
     }