1 files changed, 71 insertions, 0 deletions
diff --git a/libgcc/vtv_end_preinit.c b/libgcc/vtv_end_preinit.c
new file mode 100644
index 00000000000..53d12b07ea1
--- /dev/null
+++ b/libgcc/vtv_end_preinit.c
@@ -0,0 +1,71 @@
+/*  Copyright (C) 2012, 2013
+    Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+/* This file is part of the vtable verification feature (for a
+   detailed description of the feature, see comments in
+   vtable-verify.c).  The vtable verification feature creates
+   certain global symbols that need to be read-write sometimes during
+   program execution, and read-only at others.  It uses 'mprotect' to
+   change the memory protections of the pages on which these variables
+   are stored.  In order to not affect the protections of other
+   program variables, these variables are put into a special named
+   section, ".vtable_map_vars", which is page-aligned at the start,
+   and which is padded with a page-sized amount of zeros at the end.
+   To make this section page aligned, we create a special symbol,
+   "_vtable_map_vars_start" which we make the very first thing that
+   goes into the section.  That is defined in vtv_start.c (which
+   contains nothing else).  vtv_start.c gest compiled into
+   vtv_start.o, and vtv_start.o gets inserted into the link line
+   immediately after crtbegin.o, if the program is compiled with
+   -fvtable.verify.
+
+   In order to pad the ".vtable_map_vars" section with a page-sized
+   amount of zeros at the end, there is a second symbol,
+   _vtable_map_vars_end.  This file defines that symbol (and only this
+   symbol).  This second symbol is a page-sized array of chars,
+   zero-filled, and is the very last thing to go into the section.
+   When the GCC driver inserts vtv_start.o into the link line (just
+   after crtbegin.o) it also inserts vtv_end.o into the link line,
+   just before crtend.o.  This has the desired effect of making our
+   section page-aligned and page-size paded, ensuring that no other
+   program data lands on our pages.  */
+
+#include "vtv-change-permission.h"
+
+void
+__VLTProtectPreinit (void)
+{
+  __VLTChangePermission (__VLTP_READ_ONLY);
+}
+
+/* Page-sized variable to mark end of .vtable_map_vars section.  */
+char _vtable_map_vars_end[VTV_PAGE_SIZE]
+  __attribute__ ((__visibility__ ("protected"), used,
+		  section(".vtable_map_vars")));
+
+/* Put the function __VLTProtectPreinit into the .preinit_array
+   section.  */
+
+__attribute__ ((section (".preinit_array")))
+    typeof (__VLTProtectPreinit) *__preinit_end = __VLTProtectPreinit;