Prepare for radical source tree reorganization.zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 44 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h b/REORG.TODO/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
new file mode 100644
index 0000000000..8d474d0d04
--- /dev/null
+++ b/REORG.TODO/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
@@ -0,0 +1,44 @@
+/* Optional code to distinguish library flavours.  x86-64 version.
+   Copyright (C) 2015-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_LIBRECON_H
+
+#include <sysdeps/unix/sysv/linux/dl-librecon.h>
+
+/* Recognizing extra environment variables.  For 64-bit applications,
+   branch prediction performance may be negatively impacted when the
+   target of a branch is more than 4GB away from the branch.  Add the
+   Prefer_MAP_32BIT_EXEC bit so that mmap will try to map executable
+   pages with MAP_32BIT first.  NB: MAP_32BIT will map to lower 2GB,
+   not lower 4GB, address.  Prefer_MAP_32BIT_EXEC reduces bits available
+   for address space layout randomization (ASLR).  Prefer_MAP_32BIT_EXEC
+   is always disabled for SUID programs and can be enabled by setting
+   environment variable, LD_PREFER_MAP_32BIT_EXEC.  */
+#define EXTRA_LD_ENVVARS \
+  case 21:								  \
+    if (memcmp (envline, "PREFER_MAP_32BIT_EXEC", 21) == 0)		  \
+      GLRO(dl_x86_cpu_features).feature[index_arch_Prefer_MAP_32BIT_EXEC] \
+	|= bit_arch_Prefer_MAP_32BIT_EXEC;				  \
+    break;
+
+/* Extra unsecure variables.  The names are all stuffed in a single
+   string which means they have to be terminated with a '\0' explicitly.  */
+#define EXTRA_UNSECURE_ENVVARS \
+  "LD_PREFER_MAP_32BIT_EXEC\0"
+
+#endif /* dl-librecon.h */