Fix DL_DEBUG_UNUSED to elide the VDSO and handle PLT references properly.

	* elf/rtld.c (dl_main): If DL_DEBUG_UNUSED is enabled, turn off
	lazy binding.
	* elf/dl-lookup (_dl_lookup_symbol_x): If DL_DEBUG_UNUSED, ignore
	undefined symbol errors.

	* elf/rtlc.c (dl_main): Skip VDSO when checking for unused
	DT_NEEDED entries.

2 files changed, 16 insertions, 2 deletions

diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 839dd3a..a2a699b 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -769,7 +769,8 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
   if (__builtin_expect (current_value.s == NULL, 0))
     {
       if ((*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)
-	  && skip_map == NULL)
+	  && skip_map == NULL
+	  && !(GLRO(dl_debug_mask) & DL_DEBUG_UNUSED))
 	{
 	  /* We could find no value for a strong reference.  */
 	  const char *reference_name = undef_map ? undef_map->l_name : "";
diff --git a/elf/rtld.c b/elf/rtld.c
index 1cc9cf3..0362b14 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -1967,7 +1967,12 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
 	      if (dyn->d_tag == DT_NEEDED)
 		{
 		  l = l->l_next;
-
+#if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
+		  /* Skip the VDSO since it's not part of the list
+		     of objects we brought in via DT_NEEDED entries.  */
+		  if (l == GLRO(dl_sysinfo_map))
+		    l = l->l_next;
+#endif
 		  if (!l->l_used)
 		    {
 		      if (first)
@@ -2500,6 +2505,14 @@ warning: debug option `%s' unknown; try LD_DEBUG=help\n", copy);
       ++dl_debug;
     }
 
+  if (GLRO(dl_debug_mask) & DL_DEBUG_UNUSED)
+    {
+      /* In order to get an accurate picture of whether a particular
+	 DT_NEEDED entry is actually used we have to process both
+	 the PLT and non-PLT relocation entries.  */
+      GLRO(dl_lazy) = 0;
+    }
+
   if (GLRO(dl_debug_mask) & DL_DEBUG_HELP)
     {
       size_t cnt;