x86: Support IBT and SHSTK in Intel CET [BZ #21598]

Intel Control-flow Enforcement Technology (CET) instructions:

https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-en
forcement-technology-preview.pdf

includes Indirect Branch Tracking (IBT) and Shadow Stack (SHSTK).

GNU_PROPERTY_X86_FEATURE_1_IBT is added to GNU program property to
indicate that all executable sections are compatible with IBT when
ENDBR instruction starts each valid target where an indirect branch
instruction can land.  Linker sets GNU_PROPERTY_X86_FEATURE_1_IBT on
output only if it is set on all relocatable inputs.

On an IBT capable processor, the following steps should be taken:

1. When loading an executable without an interpreter, enable IBT and
lock IBT if GNU_PROPERTY_X86_FEATURE_1_IBT is set on the executable.
2. When loading an executable with an interpreter, enable IBT if
GNU_PROPERTY_X86_FEATURE_1_IBT is set on the interpreter.
  a. If GNU_PROPERTY_X86_FEATURE_1_IBT isn't set on the executable,
     disable IBT.
  b. Lock IBT.
3. If IBT is enabled, when loading a shared object without
GNU_PROPERTY_X86_FEATURE_1_IBT:
  a. If legacy interwork is allowed, then mark all pages in executable
     PT_LOAD segments in legacy code page bitmap.  Failure of legacy code
     page bitmap allocation causes an error.
  b. If legacy interwork isn't allowed, it causes an error.

GNU_PROPERTY_X86_FEATURE_1_SHSTK is added to GNU program property to
indicate that all executable sections are compatible with SHSTK where
return address popped from shadow stack always matches return address
popped from normal stack.  Linker sets GNU_PROPERTY_X86_FEATURE_1_SHSTK
on output only if it is set on all relocatable inputs.

On a SHSTK capable processor, the following steps should be taken:

1. When loading an executable without an interpreter, enable SHSTK if
GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on the executable.
2. When loading an executable with an interpreter, enable SHSTK if
GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on interpreter.
  a. If GNU_PROPERTY_X86_FEATURE_1_SHSTK isn't set on the executable
     or any shared objects loaded via the DT_NEEDED tag, disable SHSTK.
  b. Otherwise lock SHSTK.
3. After SHSTK is enabled, it is an error to load a shared object
without GNU_PROPERTY_X86_FEATURE_1_SHSTK.

To enable CET support in glibc, --enable-cet is required to configure
glibc.  When CET is enabled, both compiler and assembler must support
CET.  Otherwise, it is a configure-time error.

To support CET run-time control,

1. _dl_x86_feature_1 is added to the writable ld.so namespace to indicate
if IBT or SHSTK are enabled at run-time.  It should be initialized by
init_cpu_features.
2. For dynamic executables:
   a. A l_cet field is added to struct link_map to indicate if IBT or
      SHSTK is enabled in an ELF module.  _dl_process_pt_note or
      _rtld_process_pt_note is called to process PT_NOTE segment for
      GNU program property and set l_cet.
   b. _dl_open_check is added to check IBT and SHSTK compatibilty when
      dlopening a shared object.
3. Replace i386 _dl_runtime_resolve and _dl_runtime_profile with
_dl_runtime_resolve_shstk and _dl_runtime_profile_shstk, respectively if
SHSTK is enabled.

CET run-time control can be changed via GLIBC_TUNABLES with

$ export GLIBC_TUNABLES=glibc.tune.x86_shstk=[permissive|on|off]
$ export GLIBC_TUNABLES=glibc.tune.x86_ibt=[permissive|on|off]

1. permissive: SHSTK is disabled when dlopening a legacy ELF module.
2. on: IBT or SHSTK are always enabled, regardless if there are IBT or
SHSTK bits in GNU program property.
3. off: IBT or SHSTK are always disabled, regardless if there are IBT or
SHSTK bits in GNU program property.

<cet.h> from CET-enabled GCC is automatically included by assembly codes
to add GNU_PROPERTY_X86_FEATURE_1_IBT and GNU_PROPERTY_X86_FEATURE_1_SHSTK
to GNU program property.  _CET_ENDBR is added at the entrance of all
assembly functions whose address may be taken.  _CET_NOTRACK is used to
insert NOTRACK prefix with indirect jump table to support IBT.  It is
defined as notrack when _CET_NOTRACK is defined in <cet.h>.

	 [BZ #21598]
	* configure.ac: Add --enable-cet.
	* configure: Regenerated.
	* elf/Makefille (all-built-dso): Add a comment.
	* elf/dl-load.c (filebuf): Moved before "dynamic-link.h".
	Include <dl-prop.h>.
	(_dl_map_object_from_fd): Call _dl_process_pt_note on PT_NOTE
	segment.
	* elf/dl-open.c: Include <dl-prop.h>.
	(dl_open_worker): Call _dl_open_check.
	* elf/rtld.c: Include <dl-prop.h>.
	(dl_main): Call _rtld_process_pt_note on PT_NOTE segment.  Call
	_rtld_main_check.
	* sysdeps/generic/dl-prop.h: New file.
	* sysdeps/i386/dl-cet.c: Likewise.
	* sysdeps/unix/sysv/linux/x86/cpu-features.c: Likewise.
	* sysdeps/unix/sysv/linux/x86/dl-cet.h: Likewise.
	* sysdeps/x86/cet-tunables.h: Likewise.
	* sysdeps/x86/check-cet.awk: Likewise.
	* sysdeps/x86/configure: Likewise.
	* sysdeps/x86/configure.ac: Likewise.
	* sysdeps/x86/dl-cet.c: Likewise.
	* sysdeps/x86/dl-procruntime.c: Likewise.
	* sysdeps/x86/dl-prop.h: Likewise.
	* sysdeps/x86/libc-start.h: Likewise.
	* sysdeps/x86/link_map.h: Likewise.
	* sysdeps/i386/dl-trampoline.S (_dl_runtime_resolve): Add
	_CET_ENDBR.
	(_dl_runtime_profile): Likewise.
	(_dl_runtime_resolve_shstk): New.
	(_dl_runtime_profile_shstk): Likewise.
	* sysdeps/linux/x86/Makefile (sysdep-dl-routines): Add dl-cet
	if CET is enabled.
	(CFLAGS-.o): Add -fcf-protection if CET is enabled.
	(CFLAGS-.os): Likewise.
	(CFLAGS-.op): Likewise.
	(CFLAGS-.oS): Likewise.
	(asm-CPPFLAGS): Add -fcf-protection -include cet.h if CET
	is enabled.
	(tests-special): Add $(objpfx)check-cet.out.
	(cet-built-dso): New.
	(+$(cet-built-dso:=.note)): Likewise.
	(common-generated): Add $(cet-built-dso:$(common-objpfx)%=%.note).
	($(objpfx)check-cet.out): New.
	(generated): Add check-cet.out.
	* sysdeps/x86/cpu-features.c: Include <dl-cet.h> and
	<cet-tunables.h>.
	(TUNABLE_CALLBACK (set_x86_ibt)): New prototype.
	(TUNABLE_CALLBACK (set_x86_shstk)): Likewise.
	(init_cpu_features): Call get_cet_status to check CET status
	and update dl_x86_feature_1 with CET status.  Call
	TUNABLE_CALLBACK (set_x86_ibt) and TUNABLE_CALLBACK
	(set_x86_shstk).  Disable and lock CET in libc.a.
	* sysdeps/x86/cpu-tunables.c: Include <cet-tunables.h>.
	(TUNABLE_CALLBACK (set_x86_ibt)): New function.
	(TUNABLE_CALLBACK (set_x86_shstk)): Likewise.
	* sysdeps/x86/sysdep.h (_CET_NOTRACK): New.
	(_CET_ENDBR): Define if not defined.
	(ENTRY): Add _CET_ENDBR.
	* sysdeps/x86/dl-tunables.list (glibc.tune): Add x86_ibt and
	x86_shstk.
	* sysdeps/x86_64/dl-trampoline.h (_dl_runtime_resolve): Add
	_CET_ENDBR.
	(_dl_runtime_profile): Likewise.

14 files changed, 979 insertions, 0 deletions

diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index 65292f4032..e9b2d0b35d 100644
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -13,3 +13,45 @@ ifeq ($(subdir),setjmp)
 gen-as-const-headers += jmp_buf-ssp.sym
 sysdep_routines += __longjmp_cancel
 endif
+
+ifeq ($(enable-cet),yes)
+ifeq ($(subdir),elf)
+sysdep-dl-routines += dl-cet
+endif
+
+# Add -fcf-protection to CFLAGS when CET is enabled.
+CFLAGS-.o += -fcf-protection
+CFLAGS-.os += -fcf-protection
+CFLAGS-.op += -fcf-protection
+CFLAGS-.oS += -fcf-protection
+
+# Compile assembly codes with <cet.h> when CET is enabled.
+asm-CPPFLAGS += -fcf-protection -include cet.h
+
+ifeq ($(subdir),elf)
+ifeq (yes,$(build-shared))
+tests-special += $(objpfx)check-cet.out
+endif
+
+# FIXME: Can't use all-built-dso in elf/Makefile since this file is
+# processed before elf/Makefile.  Duplicate it here.
+cet-built-dso := $(common-objpfx)elf/ld.so $(common-objpfx)libc.so \
+		 $(filter-out $(common-objpfx)linkobj/libc.so, \
+			      $(sort $(wildcard $(addprefix $(common-objpfx), \
+							    */lib*.so \
+							    iconvdata/*.so))))
+
+$(cet-built-dso:=.note): %.note: %
+	@rm -f $@T
+	LC_ALL=C $(READELF) -n $< > $@T
+	test -s $@T
+	mv -f $@T $@
+common-generated += $(cet-built-dso:$(common-objpfx)%=%.note)
+
+$(objpfx)check-cet.out: $(..)sysdeps/x86/check-cet.awk \
+			$(cet-built-dso:=.note)
+	LC_ALL=C $(AWK) -f $^ > $@; \
+	$(evaluate-test)
+generated += check-cet.out
+endif
+endif
diff --git a/sysdeps/x86/cet-tunables.h b/sysdeps/x86/cet-tunables.h
new file mode 100644
index 0000000000..ca023053ee
--- /dev/null
+++ b/sysdeps/x86/cet-tunables.h
@@ -0,0 +1,29 @@
+/* x86 CET tuning.
+   This file is part of the GNU C Library.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+/* Valid control values:
+   0: Enable CET features based on ELF property note.
+   1: Always disable CET features.
+   2: Always enable CET features.
+   3: Enable CET features permissively.
+ */
+#define CET_ELF_PROPERTY	0
+#define CET_ALWAYS_OFF		1
+#define CET_ALWAYS_ON		2
+#define CET_PERMISSIVE		3
+#define CET_MAX			CET_PERMISSIVE
diff --git a/sysdeps/x86/check-cet.awk b/sysdeps/x86/check-cet.awk
new file mode 100644
index 0000000000..380d998caf
--- /dev/null
+++ b/sysdeps/x86/check-cet.awk
@@ -0,0 +1,53 @@
+# Verify that all shared objects contain the CET property.
+# Copyright (C) 2018 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/>.
+
+# This awk script expects to get command-line files that are each
+# the output of 'readelf -n' on a single shared object.
+# It exits successfully (0) if all of them contained the CET property.
+# It fails (1) if any didn't contain the CET property
+# It fails (2) if the input did not take the expected form.
+
+BEGIN { result = cet = sanity = 0 }
+
+function check_one(name) {
+  if (!sanity) {
+    print name ": *** input did not look like readelf -n output";
+    result = 2;
+  } else if (cet) {
+    print name ": OK";
+  } else {
+    print name ": *** no CET property found";
+    result = result ? result : 1;
+  }
+
+  cet = sanity = 0;
+}
+
+FILENAME != lastfile {
+  if (lastfile)
+    check_one(lastfile);
+  lastfile = FILENAME;
+}
+
+index ($0, "Displaying notes") != 0 { sanity = 1 }
+index ($0, "IBT") != 0 && index ($0, "SHSTK") != 0 { cet = 1 }
+
+END {
+  check_one(lastfile);
+  exit(result);
+}
diff --git a/sysdeps/x86/configure b/sysdeps/x86/configure
new file mode 100644
index 0000000000..b1ff281249
--- /dev/null
+++ b/sysdeps/x86/configure
@@ -0,0 +1,69 @@
+# This file is generated from configure.ac by Autoconf.  DO NOT EDIT!
+ # Local configure fragment for sysdeps/x86.
+
+if test x"$enable_cet" = xyes; then
+  # Check if CET can be enabled.
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether CET can be enabled" >&5
+$as_echo_n "checking whether CET can be enabled... " >&6; }
+if ${libc_cv_x86_cet_available+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat > conftest.c <<EOF
+#if !defined __CET__ || __CET__ != 3
+# error CET isn't available.
+#endif
+EOF
+		 if { ac_try='${CC-cc} -c $CFLAGS -fcf-protection -include cet.h conftest.c 1>&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }; then
+		   libc_cv_x86_cet_available=yes
+		 else
+		   libc_cv_x86_cet_available=no
+		 fi
+		 rm -rf conftest*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_x86_cet_available" >&5
+$as_echo "$libc_cv_x86_cet_available" >&6; }
+  if test $libc_cv_x86_cet_available = yes; then
+    enable_cet=yes
+  else
+    if test x"$enable_cet" = xdefault; then
+      enable_cet=no
+    else
+      as_fn_error $? "$CC doesn't support CET" "$LINENO" 5
+    fi
+  fi
+fi
+if test $enable_cet = yes; then
+  # Check if assembler supports CET.
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $AS supports CET" >&5
+$as_echo_n "checking whether $AS supports CET... " >&6; }
+if ${libc_cv_x86_cet_as+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat > conftest.s <<EOF
+	incsspd %ecx
+EOF
+		 if { ac_try='${CC-cc} -c $CFLAGS conftest.s -o conftest.o 1>&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }; then
+		   libc_cv_x86_cet_as=yes
+		 else
+		   libc_cv_x86_cet_as=no
+		 fi
+		 rm -rf conftest*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_x86_cet_as" >&5
+$as_echo "$libc_cv_x86_cet_as" >&6; }
+  if test $libc_cv_x86_cet_as = no; then
+    as_fn_error $? "$AS doesn't support CET" "$LINENO" 5
+  fi
+fi
+config_vars="$config_vars
+enable-cet = $enable_cet"
diff --git a/sysdeps/x86/configure.ac b/sysdeps/x86/configure.ac
new file mode 100644
index 0000000000..a909b073af
--- /dev/null
+++ b/sysdeps/x86/configure.ac
@@ -0,0 +1,46 @@
+GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
+# Local configure fragment for sysdeps/x86.
+
+if test x"$enable_cet" = xyes; then
+  # Check if CET can be enabled.
+  AC_CACHE_CHECK(whether CET can be enabled,
+		 libc_cv_x86_cet_available, [dnl
+cat > conftest.c <<EOF
+#if !defined __CET__ || __CET__ != 3
+# error CET isn't available.
+#endif
+EOF
+		 if AC_TRY_COMMAND(${CC-cc} -c $CFLAGS -fcf-protection -include cet.h conftest.c 1>&AS_MESSAGE_LOG_FD); then
+		   libc_cv_x86_cet_available=yes
+		 else
+		   libc_cv_x86_cet_available=no
+		 fi
+		 rm -rf conftest*])
+  if test $libc_cv_x86_cet_available = yes; then
+    enable_cet=yes
+  else
+    if test x"$enable_cet" = xdefault; then
+      enable_cet=no
+    else
+      AC_MSG_ERROR([$CC doesn't support CET])
+    fi
+  fi
+fi
+if test $enable_cet = yes; then
+  # Check if assembler supports CET.
+  AC_CACHE_CHECK(whether $AS supports CET,
+		 libc_cv_x86_cet_as, [dnl
+cat > conftest.s <<EOF
+	incsspd %ecx
+EOF
+		 if AC_TRY_COMMAND(${CC-cc} -c $CFLAGS conftest.s -o conftest.o 1>&AS_MESSAGE_LOG_FD); then
+		   libc_cv_x86_cet_as=yes
+		 else
+		   libc_cv_x86_cet_as=no
+		 fi
+		 rm -rf conftest*])
+  if test $libc_cv_x86_cet_as = no; then
+    AC_MSG_ERROR([$AS doesn't support CET])
+  fi
+fi
+LIBC_CONFIG_VAR([enable-cet], [$enable_cet])
diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index d41ebde823..0627f145e0 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -28,6 +28,15 @@
 
 extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *)
   attribute_hidden;
+
+# if CET_ENABLED
+#  include <dl-cet.h>
+#  include <cet-tunables.h>
+extern void TUNABLE_CALLBACK (set_x86_ibt) (tunable_val_t *)
+  attribute_hidden;
+extern void TUNABLE_CALLBACK (set_x86_shstk) (tunable_val_t *)
+  attribute_hidden;
+# endif
 #endif
 
 static void
@@ -449,4 +458,55 @@ no_cpuid:
   else if (CPU_FEATURES_ARCH_P (cpu_features, I586))
     GLRO(dl_platform) = "i586";
 #endif
+
+#if CET_ENABLED
+# if HAVE_TUNABLES
+  TUNABLE_GET (x86_ibt, tunable_val_t *,
+	       TUNABLE_CALLBACK (set_x86_ibt));
+  TUNABLE_GET (x86_shstk, tunable_val_t *,
+	       TUNABLE_CALLBACK (set_x86_shstk));
+# endif
+
+  /* Check CET status.  */
+  unsigned int cet_status = get_cet_status ();
+
+  if (cet_status)
+    {
+      GL(dl_x86_feature_1)[0] = cet_status;
+
+# ifndef SHARED
+      /* Check if IBT and SHSTK are enabled by kernel.  */
+      if ((cet_status & GNU_PROPERTY_X86_FEATURE_1_IBT)
+	  || (cet_status & GNU_PROPERTY_X86_FEATURE_1_SHSTK))
+	{
+	  /* Disable IBT and/or SHSTK if they are enabled by kernel, but
+	     disabled by environment variable:
+
+	     GLIBC_TUNABLES=glibc.tune.hwcaps=-IBT,-SHSTK
+	   */
+	  unsigned int cet_feature = 0;
+	  if (!HAS_CPU_FEATURE (IBT))
+	    cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT;
+	  if (!HAS_CPU_FEATURE (SHSTK))
+	    cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+
+	  if (cet_feature)
+	    {
+	      int res = dl_cet_disable_cet (cet_feature);
+
+	      /* Clear the disabled bits in dl_x86_feature_1.  */
+	      if (res == 0)
+		GL(dl_x86_feature_1)[0] &= ~cet_feature;
+	    }
+
+	  /* Lock CET if IBT or SHSTK is enabled in executable.  Don't
+	     lock CET if SHSTK is enabled permissively.  */
+	  if (((GL(dl_x86_feature_1)[1] >> CET_MAX)
+	       & ((1 << CET_MAX) - 1))
+	       != CET_PERMISSIVE)
+	    dl_cet_lock_cet ();
+	}
+# endif
+    }
+#endif
 }
diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c
index af761dcbbc..69155a8f44 100644
--- a/sysdeps/x86/cpu-tunables.c
+++ b/sysdeps/x86/cpu-tunables.c
@@ -334,4 +334,52 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
     }
   while (*p != '\0');
 }
+
+# if CET_ENABLED
+#  include <cet-tunables.h>
+
+attribute_hidden
+void
+TUNABLE_CALLBACK (set_x86_ibt) (tunable_val_t *valp)
+{
+  if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
+    {
+      GL(dl_x86_feature_1)[1] &= ~((1 << CET_MAX) - 1);
+      GL(dl_x86_feature_1)[1] |= CET_ALWAYS_ON;
+    }
+  else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
+    {
+      GL(dl_x86_feature_1)[1] &= ~((1 << CET_MAX) - 1);
+      GL(dl_x86_feature_1)[1] |= CET_ALWAYS_OFF;
+    }
+  else if (DEFAULT_MEMCMP (valp->strval, "permissive",
+			   sizeof ("permissive")) == 0)
+    {
+      GL(dl_x86_feature_1)[1] &= ~((1 << CET_MAX) - 1);
+      GL(dl_x86_feature_1)[1] |= CET_PERMISSIVE;
+    }
+}
+
+attribute_hidden
+void
+TUNABLE_CALLBACK (set_x86_shstk) (tunable_val_t *valp)
+{
+  if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
+    {
+      GL(dl_x86_feature_1)[1] &= ~(((1 << CET_MAX) - 1) << CET_MAX);
+      GL(dl_x86_feature_1)[1] |= (CET_ALWAYS_ON << CET_MAX);
+    }
+  else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
+    {
+      GL(dl_x86_feature_1)[1] &= ~(((1 << CET_MAX) - 1) << CET_MAX);
+      GL(dl_x86_feature_1)[1] |= (CET_ALWAYS_OFF << CET_MAX);
+    }
+  else if (DEFAULT_MEMCMP (valp->strval, "permissive",
+			   sizeof ("permissive")) == 0)
+    {
+      GL(dl_x86_feature_1)[1] &= ~(((1 << CET_MAX) - 1) << CET_MAX);
+      GL(dl_x86_feature_1)[1] |= (CET_PERMISSIVE << CET_MAX);
+    }
+}
+# endif
 #endif
diff --git a/sysdeps/x86/dl-cet.c b/sysdeps/x86/dl-cet.c
new file mode 100644
index 0000000000..b82ba14e75
--- /dev/null
+++ b/sysdeps/x86/dl-cet.c
@@ -0,0 +1,346 @@
+/* x86 CET initializers function.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <unistd.h>
+#include <errno.h>
+#include <libintl.h>
+#include <ldsodefs.h>
+#include <dl-cet.h>
+#include <cet-tunables.h>
+
+/* GNU_PROPERTY_X86_FEATURE_1_IBT and GNU_PROPERTY_X86_FEATURE_1_SHSTK
+   are defined in <elf.h>, which are only available for C sources.
+   X86_FEATURE_1_IBT and X86_FEATURE_1_SHSTK are defined in <sysdep.h>
+   which are available for both C and asm sources.  They must match.   */
+#if GNU_PROPERTY_X86_FEATURE_1_IBT != X86_FEATURE_1_IBT
+# error GNU_PROPERTY_X86_FEATURE_1_IBT != X86_FEATURE_1_IBT
+#endif
+#if GNU_PROPERTY_X86_FEATURE_1_SHSTK != X86_FEATURE_1_SHSTK
+# error GNU_PROPERTY_X86_FEATURE_1_SHSTK != X86_FEATURE_1_SHSTK
+#endif
+
+static int
+dl_cet_mark_legacy_region (struct link_map *l)
+{
+  /* Mark PT_LOAD segments with PF_X in legacy code page bitmap.  */
+  size_t i, phnum = l->l_phnum;
+  const ElfW(Phdr) *phdr = l->l_phdr;
+#ifdef __x86_64__
+  typedef unsigned long long word_t;
+#else
+  typedef unsigned long word_t;
+#endif
+  unsigned int bits_to_set;
+  word_t mask_to_set;
+#define BITS_PER_WORD (sizeof (word_t) * 8)
+#define BITMAP_FIRST_WORD_MASK(start) \
+  (~((word_t) 0) << ((start) & (BITS_PER_WORD - 1)))
+#define BITMAP_LAST_WORD_MASK(nbits) \
+  (~((word_t) 0) >> (-(nbits) & (BITS_PER_WORD - 1)))
+
+  word_t *bitmap = (word_t *) GL(dl_x86_legacy_bitmap)[0];
+  word_t bitmap_size = GL(dl_x86_legacy_bitmap)[1];
+  word_t *p;
+  size_t page_size = GLRO(dl_pagesize);
+
+  for (i = 0; i < phnum; i++)
+    if (phdr[i].p_type == PT_LOAD && (phdr[i].p_flags & PF_X))
+      {
+	/* One bit in legacy bitmap represents a page.  */
+	ElfW(Addr) start = (phdr[i].p_vaddr + l->l_addr) / page_size;
+	ElfW(Addr) len = (phdr[i].p_memsz + page_size - 1) / page_size;
+	ElfW(Addr) end = start + len;
+
+	if ((end / 8) > bitmap_size)
+	  return -EINVAL;
+
+	p = bitmap + (start / BITS_PER_WORD);
+	bits_to_set = BITS_PER_WORD - (start % BITS_PER_WORD);
+	mask_to_set = BITMAP_FIRST_WORD_MASK (start);
+
+	while (len >= bits_to_set)
+	  {
+	    *p |= mask_to_set;
+	    len -= bits_to_set;
+	    bits_to_set = BITS_PER_WORD;
+	    mask_to_set = ~((word_t) 0);
+	    p++;
+	  }
+	if (len)
+	  {
+	    mask_to_set &= BITMAP_LAST_WORD_MASK (end);
+	    *p |= mask_to_set;
+	  }
+      }
+
+  return 0;
+}
+
+/* Check if object M is compatible with CET.  */
+
+static void
+dl_cet_check (struct link_map *m, const char *program)
+{
+  /* Check how IBT should be enabled.  */
+  unsigned int enable_ibt_type
+    = GL(dl_x86_feature_1)[1] & ((1 << CET_MAX) - 1);
+  /* Check how SHSTK should be enabled.  */
+  unsigned int enable_shstk_type
+    = ((GL(dl_x86_feature_1)[1] >> CET_MAX) & ((1 << CET_MAX) - 1));
+
+  /* No legacy object check if both IBT and SHSTK are always on.  */
+  if (enable_ibt_type == CET_ALWAYS_ON
+      && enable_shstk_type == CET_ALWAYS_ON)
+    return;
+
+  /* Check if IBT is enabled by kernel.  */
+  bool ibt_enabled
+    = (GL(dl_x86_feature_1)[0] & GNU_PROPERTY_X86_FEATURE_1_IBT) != 0;
+  /* Check if SHSTK is enabled by kernel.  */
+  bool shstk_enabled
+    = (GL(dl_x86_feature_1)[0] & GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0;
+
+  if (ibt_enabled || shstk_enabled)
+    {
+      struct link_map *l = NULL;
+
+      /* Check if IBT and SHSTK are enabled in object.  */
+      bool enable_ibt = (ibt_enabled
+			 && enable_ibt_type != CET_ALWAYS_OFF);
+      bool enable_shstk = (shstk_enabled
+			   && enable_shstk_type != CET_ALWAYS_OFF);
+      if (program)
+	{
+	  /* Enable IBT and SHSTK only if they are enabled in executable.
+	     NB: IBT and SHSTK may be disabled by environment variable:
+
+	     GLIBC_TUNABLES=glibc.tune.hwcaps=-IBT,-SHSTK
+	   */
+	  enable_ibt &= (HAS_CPU_FEATURE (IBT)
+			 && (enable_ibt_type == CET_ALWAYS_ON
+			     || (m->l_cet & lc_ibt) != 0));
+	  enable_shstk &= (HAS_CPU_FEATURE (SHSTK)
+			   && (enable_shstk_type == CET_ALWAYS_ON
+			       || (m->l_cet & lc_shstk) != 0));
+	}
+
+      /* ld.so is CET-enabled by kernel.  But shared objects may not
+	 support IBT nor SHSTK.  */
+      if (enable_ibt || enable_shstk)
+	{
+	  int res;
+	  unsigned int i;
+	  unsigned int first_legacy, last_legacy;
+	  bool need_legacy_bitmap = false;
+
+	  i = m->l_searchlist.r_nlist;
+	  while (i-- > 0)
+	    {
+	      /* Check each shared object to see if IBT and SHSTK are
+		 enabled.  */
+	      l = m->l_initfini[i];
+
+	      if (l->l_init_called)
+		continue;
+
+#ifdef SHARED
+	      /* Skip CET check for ld.so since ld.so is CET-enabled.
+		 CET will be disabled later if CET isn't enabled in
+		 executable.  */
+	      if (l == &GL(dl_rtld_map)
+		  ||  l->l_real == &GL(dl_rtld_map)
+		  || (program && l == m))
+		continue;
+#endif
+
+	      if (enable_ibt
+		  && enable_ibt_type != CET_ALWAYS_ON
+		  && !(l->l_cet & lc_ibt))
+		{
+		  /* Remember the first and last legacy objects.  */
+		  if (!need_legacy_bitmap)
+		    last_legacy = i;
+		  first_legacy = i;
+		  need_legacy_bitmap = true;
+		}
+
+	      /* SHSTK is enabled only if it is enabled in executable as
+		 well as all shared objects.  */
+	      enable_shstk &= (enable_shstk_type == CET_ALWAYS_ON
+			       || (l->l_cet & lc_shstk) != 0);
+	    }
+
+	  if (need_legacy_bitmap)
+	    {
+	      if (GL(dl_x86_legacy_bitmap)[0])
+		{
+		  /* Change legacy bitmap to writable.  */
+		  if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0],
+				  GL(dl_x86_legacy_bitmap)[1],
+				  PROT_READ | PROT_WRITE) < 0)
+		    {
+mprotect_failure:
+		      if (program)
+			_dl_fatal_printf ("%s: mprotect legacy bitmap failed\n",
+					  l->l_name);
+		      else
+			_dl_signal_error (EINVAL, l->l_name, "dlopen",
+					  N_("mprotect legacy bitmap failed"));
+		    }
+		}
+	      else
+		{
+		  /* Allocate legacy bitmap.  */
+		  int res = dl_cet_allocate_legacy_bitmap
+		    (GL(dl_x86_legacy_bitmap));
+		  if (res != 0)
+		    {
+		      if (program)
+			_dl_fatal_printf ("%s: legacy bitmap isn't available\n",
+					  l->l_name);
+		      else
+			_dl_signal_error (EINVAL, l->l_name, "dlopen",
+					  N_("legacy bitmap isn't available"));
+		    }
+		}
+
+	      /* Put legacy shared objects in legacy bitmap.  */
+	      for (i = first_legacy; i <= last_legacy; i++)
+		{
+		  l = m->l_initfini[i];
+
+		  if (l->l_init_called || (l->l_cet & lc_ibt))
+		    continue;
+
+#ifdef SHARED
+		  if (l == &GL(dl_rtld_map)
+		      ||  l->l_real == &GL(dl_rtld_map)
+		      || (program && l == m))
+		    continue;
+#endif
+
+		  /* If IBT is enabled in executable and IBT isn't enabled
+		     in this shard object, mark PT_LOAD segments with PF_X
+		     in legacy code page bitmap.  */
+		  res = dl_cet_mark_legacy_region (l);
+		  if (res != 0)
+		    {
+		      if (program)
+			_dl_fatal_printf ("%s: failed to mark legacy code region\n",
+					  l->l_name);
+		      else
+			_dl_signal_error (-res, l->l_name, "dlopen",
+					  N_("failed to mark legacy code region"));
+		    }
+		}
+
+	      /* Change legacy bitmap to read-only.  */
+	      if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0],
+			      GL(dl_x86_legacy_bitmap)[1], PROT_READ) < 0)
+		goto mprotect_failure;
+	    }
+	}
+
+      bool cet_feature_changed = false;
+
+      if (enable_ibt != ibt_enabled || enable_shstk != shstk_enabled)
+	{
+	  if (!program
+	      && enable_shstk_type != CET_PERMISSIVE)
+	    {
+	      /* When SHSTK is enabled, we can't dlopening a shared
+		 object without SHSTK.  */
+	      if (enable_shstk != shstk_enabled)
+		_dl_signal_error (EINVAL, l->l_name, "dlopen",
+				  N_("shadow stack isn't enabled"));
+	      return;
+	    }
+
+	  /* Disable IBT and/or SHSTK if they are enabled by kernel, but
+	     disabled in executable or shared objects.  */
+	  unsigned int cet_feature = 0;
+
+	  /* Disable IBT only during program startup.  */
+	  if (program && !enable_ibt)
+	    cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT;
+	  if (!enable_shstk)
+	    cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+
+	  int res = dl_cet_disable_cet (cet_feature);
+	  if (res != 0)
+	    {
+	      if (program)
+		_dl_fatal_printf ("%s: can't disable CET\n", program);
+	      else
+		_dl_signal_error (-res, l->l_name, "dlopen",
+				  N_("can't disable CET"));
+	    }
+
+	  /* Clear the disabled bits in dl_x86_feature_1.  */
+	  GL(dl_x86_feature_1)[0] &= ~cet_feature;
+
+	  cet_feature_changed = true;
+	}
+
+#ifdef SHARED
+      if (program
+	  && (!shstk_enabled
+	      || enable_shstk_type != CET_PERMISSIVE)
+	  && (ibt_enabled || shstk_enabled))
+	{
+	  /* Lock CET if IBT or SHSTK is enabled in executable.  Don't
+	     lock CET if SHSTK is enabled permissively.  */
+	  int res = dl_cet_lock_cet ();
+	  if (res != 0)
+	    _dl_fatal_printf ("%s: can't lock CET\n", program);
+
+	  cet_feature_changed = true;
+	}
+#endif
+
+      if (cet_feature_changed)
+	{
+	  unsigned int feature_1 = 0;
+	  if (enable_ibt)
+	    feature_1 |= GNU_PROPERTY_X86_FEATURE_1_IBT;
+	  if (enable_shstk)
+	    feature_1 |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+	  struct pthread *self = THREAD_SELF;
+	  THREAD_SETMEM (self, header.feature_1, feature_1);
+	}
+    }
+}
+
+void
+_dl_cet_open_check (struct link_map *l)
+{
+  dl_cet_check (l, NULL);
+}
+
+#ifdef SHARED
+
+# ifndef LINKAGE
+#  define LINKAGE
+# endif
+
+LINKAGE
+void
+_dl_cet_check (struct link_map *main_map, const char *program)
+{
+  dl_cet_check (main_map, program);
+}
+#endif /* SHARED */
diff --git a/sysdeps/x86/dl-procruntime.c b/sysdeps/x86/dl-procruntime.c
new file mode 100644
index 0000000000..eddbde6a31
--- /dev/null
+++ b/sysdeps/x86/dl-procruntime.c
@@ -0,0 +1,68 @@
+/* Data for processor runtime information.  x86 version.
+   Copyright (C) 2018 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/>.  */
+
+/* This information must be kept in sync with the _DL_HWCAP_COUNT,
+   HWCAP_PLATFORMS_START and HWCAP_PLATFORMS_COUNT definitions in
+   dl-hwcap.h.
+
+   If anything should be added here check whether the size of each string
+   is still ok with the given array size.
+
+   All the #ifdefs in the definitions are quite irritating but
+   necessary if we want to avoid duplicating the information.  There
+   are three different modes:
+
+   - PROCINFO_DECL is defined.  This means we are only interested in
+     declarations.
+
+   - PROCINFO_DECL is not defined:
+
+     + if SHARED is defined the file is included in an array
+       initializer.  The .element = { ... } syntax is needed.
+
+     + if SHARED is not defined a normal array initialization is
+       needed.
+  */
+
+#ifndef PROCINFO_CLASS
+# define PROCINFO_CLASS
+#endif
+
+#if !IS_IN (ldconfig)
+# if !defined PROCINFO_DECL && defined SHARED
+  ._dl_x86_feature_1
+# else
+PROCINFO_CLASS unsigned int _dl_x86_feature_1[2]
+# endif
+# if !defined SHARED || defined PROCINFO_DECL
+;
+# else
+,
+# endif
+
+# if !defined PROCINFO_DECL && defined SHARED
+  ._dl_x86_legacy_bitmap
+# else
+PROCINFO_CLASS unsigned long _dl_x86_legacy_bitmap[2]
+# endif
+# if !defined SHARED || defined PROCINFO_DECL
+;
+# else
+,
+# endif
+#endif
diff --git a/sysdeps/x86/dl-prop.h b/sysdeps/x86/dl-prop.h
new file mode 100644
index 0000000000..d56e20a6dc
--- /dev/null
+++ b/sysdeps/x86/dl-prop.h
@@ -0,0 +1,153 @@
+/* Support for GNU properties.  x86 version.
+   Copyright (C) 2018 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_PROP_H
+#define _DL_PROP_H
+
+#include <not-cancel.h>
+
+extern void _dl_cet_check (struct link_map *, const char *)
+    attribute_hidden;
+extern void _dl_cet_open_check (struct link_map *)
+    attribute_hidden;
+
+static inline void __attribute__ ((always_inline))
+_rtld_main_check (struct link_map *m, const char *program)
+{
+#if CET_ENABLED
+  _dl_cet_check (m, program);
+#endif
+}
+
+static inline void __attribute__ ((always_inline))
+_dl_open_check (struct link_map *m)
+{
+#if CET_ENABLED
+  _dl_cet_open_check (m);
+#endif
+}
+
+static inline void __attribute__ ((unused))
+_dl_process_cet_property_note (struct link_map *l,
+			      const ElfW(Nhdr) *note,
+			      const ElfW(Addr) size,
+			      const ElfW(Addr) align)
+{
+#if CET_ENABLED
+  /* The NT_GNU_PROPERTY_TYPE_0 note must be aliged to 4 bytes in
+     32-bit objects and to 8 bytes in 64-bit objects.  Skip notes
+     with incorrect alignment.  */
+  if (align != (__ELF_NATIVE_CLASS / 8))
+    return;
+
+  const ElfW(Addr) start = (ElfW(Addr)) note;
+
+  while ((ElfW(Addr)) (note + 1) - start < size)
+    {
+      /* Find the NT_GNU_PROPERTY_TYPE_0 note.  */
+      if (note->n_namesz == 4
+	  && note->n_type == NT_GNU_PROPERTY_TYPE_0
+	  && memcmp (note + 1, "GNU", 4) == 0)
+	{
+	  /* Check for invalid property.  */
+	  if (note->n_descsz < 8
+	      || (note->n_descsz % sizeof (ElfW(Addr))) != 0)
+	    break;
+
+	  /* Start and end of property array.  */
+	  unsigned char *ptr = (unsigned char *) (note + 1) + 4;
+	  unsigned char *ptr_end = ptr + note->n_descsz;
+
+	  while (1)
+	    {
+	      unsigned int type = *(unsigned int *) ptr;
+	      unsigned int datasz = *(unsigned int *) (ptr + 4);
+
+	      ptr += 8;
+	      if ((ptr + datasz) > ptr_end)
+		break;
+
+	      if (type == GNU_PROPERTY_X86_FEATURE_1_AND
+		  && datasz == 4)
+		{
+		  unsigned int feature_1 = *(unsigned int *) ptr;
+		  if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_IBT))
+		    l->l_cet |= lc_ibt;
+		  if ((feature_1 & GNU_PROPERTY_X86_FEATURE_1_SHSTK))
+		    l->l_cet |= lc_shstk;
+		  break;
+		}
+	    }
+	}
+
+      /* NB: Note sections like .note.ABI-tag and .note.gnu.build-id are
+	 aligned to 4 bytes in 64-bit ELF objects.  */
+      note = ((const void *) note
+	      + ELF_NOTE_NEXT_OFFSET (note->n_namesz, note->n_descsz,
+				      align));
+    }
+#endif
+}
+
+#ifdef FILEBUF_SIZE
+static inline int __attribute__ ((unused))
+_dl_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph,
+		     int fd, struct filebuf *fbp)
+{
+# if CET_ENABLED
+  const ElfW(Nhdr) *note;
+  ElfW(Nhdr) *note_malloced = NULL;
+  ElfW(Addr) size = ph->p_filesz;
+
+  if (ph->p_offset + size <= (size_t) fbp->len)
+    note = (const void *) (fbp->buf + ph->p_offset);
+  else
+    {
+      if (size < __MAX_ALLOCA_CUTOFF)
+	note = alloca (size);
+      else
+	{
+	  note_malloced = malloc (size);
+	  note = note_malloced;
+	}
+      __lseek (fd, ph->p_offset, SEEK_SET);
+      if (__read_nocancel (fd, (void *) note, size) != size)
+	{
+	  if (note_malloced)
+	    free (note_malloced);
+	  return -1;
+	}
+    }
+
+  _dl_process_cet_property_note (l, note, size, ph->p_align);
+  if (note_malloced)
+    free (note_malloced);
+# endif
+  return 0;
+}
+#endif
+
+static inline int __attribute__ ((unused))
+_rtld_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph)
+{
+  const ElfW(Nhdr) *note = (const void *) (ph->p_vaddr + l->l_addr);
+  _dl_process_cet_property_note (l, note, ph->p_memsz, ph->p_align);
+  return 0;
+}
+
+#endif /* _DL_PROP_H */
diff --git a/sysdeps/x86/dl-tunables.list b/sysdeps/x86/dl-tunables.list
index 7c3236a68f..73886b1352 100644
--- a/sysdeps/x86/dl-tunables.list
+++ b/sysdeps/x86/dl-tunables.list
@@ -21,6 +21,12 @@ glibc {
     hwcaps {
       type: STRING
     }
+    x86_ibt {
+      type: STRING
+    }
+    x86_shstk {
+      type: STRING
+    }
     x86_non_temporal_threshold {
       type: SIZE_T
     }
diff --git a/sysdeps/x86/libc-start.h b/sysdeps/x86/libc-start.h
new file mode 100644
index 0000000000..6f44262bf4
--- /dev/null
+++ b/sysdeps/x86/libc-start.h
@@ -0,0 +1,25 @@
+/* X86 definitions for libc main startup.
+   Copyright (C) 2018 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 SHARED
+# define ARCH_SETUP_IREL() apply_irel ()
+# define ARCH_APPLY_IREL()
+# ifndef ARCH_SETUP_TLS
+#  define ARCH_SETUP_TLS() __libc_setup_tls ()
+# endif
+#endif /* !SHARED */
diff --git a/sysdeps/x86/link_map.h b/sysdeps/x86/link_map.h
new file mode 100644
index 0000000000..ef1206a9d2
--- /dev/null
+++ b/sysdeps/x86/link_map.h
@@ -0,0 +1,26 @@
+/* Additional fields in struct link_map.  Linux/x86 version.
+   Copyright (C) 2018 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/>.  */
+
+/* If this object is enabled with CET.  */
+enum
+  {
+    lc_none = 0,			 /* Not enabled with CET.  */
+    lc_ibt = 1 << 0,			 /* Enabled with IBT.  */
+    lc_shstk = 1 << 1,			 /* Enabled with STSHK.  */
+    lc_ibt_and_shstk = lc_ibt | lc_shstk /* Enabled with both.  */
+  } l_cet:2;
diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
index 976566aa37..8776ad8374 100644
--- a/sysdeps/x86/sysdep.h
+++ b/sysdeps/x86/sysdep.h
@@ -52,6 +52,13 @@ enum cf_protection_level
 
 /* Syntactic details of assembler.  */
 
+#ifdef _CET_ENDBR
+# define _CET_NOTRACK notrack
+#else
+# define _CET_ENDBR
+# define _CET_NOTRACK
+#endif
+
 /* ELF uses byte-counts for .align, most others use log2 of count of bytes.  */
 #define ALIGNARG(log2) 1<<log2
 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name;
@@ -63,6 +70,7 @@ enum cf_protection_level
   .align ALIGNARG(4);							      \
   C_LABEL(name)								      \
   cfi_startproc;							      \
+  _CET_ENDBR;								      \
   CALL_MCOUNT
 
 #undef	END