elf: Do not copy vDSO soname when setting up link map

The kernel does not put the vDSO at special addresses, so writev can
write the name directly.  Also remove the incorrect comment about not
setting l_name.

Andy Lutomirski confirmed in
<https://lore.kernel.org/linux-api/442A16C0-AE5A-4A44-B261-FE6F817EAF3C@amacapital.net/>
that this copy is not necessary.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

diff --git a/elf/setup-vdso.h b/elf/setup-vdso.h
index ece840df38cc6c55936d563d045dd23faf016aee..86c491e49c98345dc3bf29878bfaa82ddfafa1f7 100644 (file)
--- a/elf/setup-vdso.h
+++ b/elf/setup-vdso.h
@@ -80,20 +80,13 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
       l->l_local_scope[0]->r_list = &l->l_real;
 
       /* Now that we have the info handy, use the DSO image's soname
-        so this object can be looked up by name.  Note that we do not
-        set l_name here.  That field gives the file name of the DSO,
-        and this DSO is not associated with any file.  */
+        so this object can be looked up by name.  */
       if (l->l_info[DT_SONAME] != NULL)
        {
-         /* Work around a kernel problem.  The kernel cannot handle
-            addresses in the vsyscall DSO pages in writev() calls.  */
-         const char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB])
-                                + l->l_info[DT_SONAME]->d_un.d_val);
-         size_t len = strlen (dsoname) + 1;
-         char *copy = malloc (len);
-         if (copy == NULL)
-           _dl_fatal_printf ("out of memory\n");
-         l->l_libname->name = l->l_name = memcpy (copy, dsoname, len);
+         char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB])
+                          + l->l_info[DT_SONAME]->d_un.d_val);
+         l->l_libname->name = dsoname;
+         l->l_name = dsoname;
        }
 
       /* Add the vDSO to the object list.  */