x86: Move CET control to _dl_x86_feature_control [BZ #25887]

1. Include <dl-procruntime.c> to get architecture specific initializer in
rtld_global.
2. Change _dl_x86_feature_1[2] to _dl_x86_feature_1.
3. Add _dl_x86_feature_control after _dl_x86_feature_1, which is a
struct of 2 bitfields for IBT and SHSTK control

This fixes [BZ #25887].

1 files changed, 41 insertions, 0 deletions

diff --git a/sysdeps/x86/cet-control.h b/sysdeps/x86/cet-control.h
new file mode 100644
index 0000000000..e163a7f55b
--- /dev/null
+++ b/sysdeps/x86/cet-control.h
@@ -0,0 +1,41 @@
+/* x86 CET tuning.
+   This file is part of the GNU C Library.
+   Copyright (C) 2018-2020 Free Software Foundation, Inc.
+
+   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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _CET_CONTROL_H
+#define _CET_CONTROL_H
+
+/* For each CET feature, IBT and SHSTK, valid control values.  */
+enum dl_x86_cet_control
+{
+  /* Enable CET features based on ELF property note.  */
+  cet_elf_property = 0,
+  /* Always enable CET features.  */
+  cet_always_on,
+  /* Always disable CET features.  */
+  cet_always_off,
+  /* Enable CET features permissively.  */
+  cet_permissive
+};
+
+struct dl_x86_feature_control
+{
+  enum dl_x86_cet_control ibt : 2;
+  enum dl_x86_cet_control shstk : 2;
+};
+
+#endif /* cet-control.h */