1 files changed, 103 insertions, 41 deletions

diff --git a/elf/dl-debug.c b/elf/dl-debug.c
index 5ff1460..38a5b9a 100644
--- a/elf/dl-debug.c
+++ b/elf/dl-debug.c
@@ -16,6 +16,7 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <assert.h>
 #include <ldsodefs.h>
 
 
@@ -30,23 +31,86 @@ extern const int verify_link_map_members[(VERIFY_MEMBER (l_addr)
 					  && VERIFY_MEMBER (l_prev))
 					 ? 1 : -1];
 
+#ifdef SHARED
+/* r_debug structs for secondary namespaces.  The first namespace is
+   handled separately because its r_debug structure must overlap with
+   the public _r_debug symbol, so the first array element corresponds
+   to LM_ID_BASE + 1.  See elf/dl-debug-symbols.S.  */
+struct r_debug_extended _r_debug_array[DL_NNS - 1];
+
+/* If not null, pointer to the _r_debug in the main executable.  */
+static struct r_debug *_r_debug_main;
+
+void
+_dl_debug_post_relocate (struct link_map *main_map)
+{
+  /* Perform a full symbol search in all objects, to maintain
+     compatibility if interposed _r_debug definitions.  The lookup
+     cannot fail because there is a definition in ld.so, and this
+     function is only called if the ld.so search scope is not empty.  */
+  const ElfW(Sym) *sym = NULL;
+  lookup_t result =_dl_lookup_symbol_x ("_r_debug", main_map, &sym,
+					main_map->l_scope, NULL, 0, 0, NULL);
+  if (sym->st_size >= sizeof (struct r_debug))
+    {
+      struct r_debug *main_r_debug = DL_SYMBOL_ADDRESS (result, sym);
+      if (main_r_debug != &_r_debug_extended.base)
+	{
+	  /* The extended version of the struct is not available in
+	     the main executable because a copy relocation has been
+	     used.  r_map etc. have already been copied as part of the
+	     copy relocation processing.  */
+	  main_r_debug->r_version = 1;
+
+          /* Record that dual updates of the initial link map are
+             required.  */
+          _r_debug_main = main_r_debug;
+	}
+    }
+}
+
+/* Return the r_debug object for the namespace NS.  */
+static inline struct r_debug_extended *
+get_rdebug (Lmid_t ns)
+{
+  if (ns == LM_ID_BASE)
+    return &_r_debug_extended;
+  else
+    return  &_r_debug_array[ns - 1];
+}
+#else /* !SHARED */
+static inline struct r_debug_extended *
+get_rdebug (Lmid_t ns)
+{
+  return &_r_debug_extended; /* There is just one namespace.  */
+}
+#endif  /* !SHARED */
+
 /* Update the `r_map' member and return the address of `struct r_debug'
    of the namespace NS. */
 
 struct r_debug *
 _dl_debug_update (Lmid_t ns)
 {
-  struct r_debug_extended *r;
-  if (ns == LM_ID_BASE)
-    r = &_r_debug_extended;
-  else
-    r = &GL(dl_ns)[ns]._ns_debug;
+  struct r_debug_extended *r = get_rdebug (ns);
   if (r->base.r_map == NULL)
     atomic_store_release (&r->base.r_map,
 			  (void *) GL(dl_ns)[ns]._ns_loaded);
   return &r->base;
 }
 
+void
+_dl_debug_change_state (struct r_debug *r, int state)
+{
+  atomic_store_release (&r->r_state, state);
+#ifdef SHARED
+  if (r == &_r_debug_extended.base && _r_debug_main != NULL)
+    /* Update the copy-relocation of _r_debug.  */
+    atomic_store_release (&_r_debug_main->r_state, state);
+#endif
+  _dl_debug_state ();
+}
+
 /* Initialize _r_debug_extended for the namespace NS.  LDBASE is the
    run-time load address of the dynamic linker, to be put in
    _r_debug_extended.r_ldbase.  Return the address of _r_debug.  */
@@ -54,34 +118,7 @@ _dl_debug_update (Lmid_t ns)
 struct r_debug *
 _dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
 {
-  struct r_debug_extended *r, **pp = NULL;
-
-  if (ns == LM_ID_BASE)
-    {
-      r = &_r_debug_extended;
-      /* Initialize r_version to 1.  */
-      if (_r_debug_extended.base.r_version == 0)
-	_r_debug_extended.base.r_version = 1;
-    }
-  else if (DL_NNS > 1)
-    {
-      r = &GL(dl_ns)[ns]._ns_debug;
-      if (r->base.r_brk == 0)
-	{
-	  /* Add the new namespace to the linked list.  After a namespace
-	     is initialized, r_brk becomes non-zero.  A namespace becomes
-	     empty (r_map == NULL) when it is unused.  But it is never
-	     removed from the linked list.  */
-	  struct r_debug_extended *p;
-	  for (pp = &_r_debug_extended.r_next;
-	       (p = *pp) != NULL;
-	       pp = &p->r_next)
-	    ;
-
-	  r->base.r_version = 2;
-	}
-    }
-
+  struct r_debug_extended *r = get_rdebug (ns);
   if (r->base.r_brk == 0)
     {
       /* Tell the debugger where to find the map of loaded objects.
@@ -89,18 +126,43 @@ _dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
 	 only once.  */
       r->base.r_ldbase = ldbase ?: _r_debug_extended.base.r_ldbase;
       r->base.r_brk = (ElfW(Addr)) &_dl_debug_state;
-      r->r_next = NULL;
+
+#ifdef SHARED
+      /* Add the new namespace to the linked list.  This assumes that
+	 namespaces are allocated in increasing order.  After a
+	 namespace is initialized, r_brk becomes non-zero.  A
+	 namespace becomes empty (r_map == NULL) when it is unused.
+	 But it is never removed from the linked list.  */
+
+      if (ns != LM_ID_BASE)
+	{
+	  r->base.r_version = 2;
+	  if (ns - 1 == LM_ID_BASE)
+	    {
+	      atomic_store_release (&_r_debug_extended.r_next, r);
+	      /* Now there are multiple namespaces.  Note that this
+		 deliberately does not update the copy in the main
+		 executable (if it exists).  */
+	      atomic_store_release (&_r_debug_extended.base.r_version, 2);
+	    }
+	  else
+	    /* Update r_debug_extended of the previous namespace.  */
+	    atomic_store_release (&_r_debug_array[ns - 2].r_next, r);
+	}
+      else
+#endif /* SHARED */
+	r->base.r_version = 1;
     }
 
   if (r->base.r_map == NULL)
-    atomic_store_release (&r->base.r_map,
-			  (void *) GL(dl_ns)[ns]._ns_loaded);
-
-  if (pp != NULL)
     {
-      atomic_store_release (pp, r);
-      /* Bump r_version to 2 for the new namespace.  */
-      atomic_store_release (&_r_debug_extended.base.r_version, 2);
+      struct link_map_public *l = (void *) GL(dl_ns)[ns]._ns_loaded;
+      atomic_store_release (&r->base.r_map, l);
+#ifdef SHARED
+      if (ns == LM_ID_BASE && _r_debug_main != NULL)
+	/* Update the copy-relocation of _r_debug.  */
+	atomic_store_release (&_r_debug_main->r_map, l);
+#endif
     }
 
   return &r->base;