Enable building libgcc with CET options.

Enable building libgcc with CET options by default on Linux/x86 if
binutils supports CET v2.0.  It can be disabled with --disable-cet.
It is an error to configure GCC with --enable-cet if bintuiils
doesn't support CET v2.0.

ENDBR instruction is added to __morestack_large_model since it is
called indirectly.

2017-11-17  Igor Tsimbalist  <igor.v.tsimbalist@intel.com>

config/
	* cet.m4: New file.

gcc/
	* config.gcc (extra_headers): Add cet.h for x86 targets.
	* config/i386/cet.h: New file.
	* doc/install.texi: Add --enable-cet/--disable-cet.

libgcc/
	* Makefile.in (configure_deps): Add $(srcdir)/../config/cet.m4.
	(CET_FLAGS): New.
	* config/i386/morestack.S: Include <cet.h>.
	(__morestack_large_model): Add _CET_ENDBR at function entrance.
	* config/i386/resms64.h: Include <cet.h>.
	* config/i386/resms64f.h: Likewise.
	* config/i386/resms64fx.h: Likewise.
	* config/i386/resms64x.h: Likewise.
	* config/i386/savms64.h: Likewise.
	* config/i386/savms64f.h: Likewise.
	* config/i386/t-linux (HOST_LIBGCC2_CFLAGS): Add $(CET_FLAGS).
	(CRTSTUFF_T_CFLAGS): Likewise.
	* configure.ac: Include ../config/cet.m4.
	Set and substitute CET_FLAGS.
	* configure: Regenerated.

From-SVN: r254868

1 files changed, 72 insertions, 0 deletions

diff --git a/libgcc/configure b/libgcc/configure
index 20169b1..38a28c2 100644
--- a/libgcc/configure
+++ b/libgcc/configure
@@ -573,6 +573,7 @@ vis_hide
 real_host_noncanonical
 accel_dir_suffix
 force_explicit_eh_registry
+CET_FLAGS
 fixed_point
 enable_decimal_float
 decimal_float
@@ -675,6 +676,7 @@ with_build_libsubdir
 enable_largefile
 enable_decimal_float
 with_system_libunwind
+enable_cet
 enable_explicit_exception_frame_registration
 with_glibc_version
 enable_tls
@@ -1314,6 +1316,8 @@ Optional Features:
 			enable decimal float extension to C.  Selecting 'bid'
 			or 'dpd' choses which decimal floating point format
 			to use
+  --enable-cet            enable Intel CET in target libraries
+                          [default=default]
   --enable-explicit-exception-frame-registration
                           register exception tables explicitly at module
                           start, for use e.g. for compatibility with
@@ -4773,6 +4777,74 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_sjlj_exceptions" >&5
 $as_echo "$ac_cv_sjlj_exceptions" >&6; }
 
+ # Check whether --enable-cet was given.
+if test "${enable_cet+set}" = set; then :
+  enableval=$enable_cet;
+      case "$enableval" in
+       yes|no|default) ;;
+       *) as_fn_error "Unknown argument to enable/disable cet" "$LINENO" 5 ;;
+                          esac
+
+else
+  enable_cet=default
+fi
+
+
+case "$host" in
+  i[34567]86-*-linux* | x86_64-*-linux*)
+    case "$enable_cet" in
+      default)
+	# Check if assembler supports CET.
+	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+asm ("setssbsy");
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  enable_cet=yes
+else
+  enable_cet=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+	;;
+      yes)
+	# Check if assembler supports CET.
+	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+asm ("setssbsy");
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+else
+  as_fn_error "assembler with CET support is required for --enable-cet" "$LINENO" 5
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+	;;
+    esac
+    ;;
+  *)
+    enable_cet=no
+    ;;
+esac
+if test x$enable_cet = xyes; then
+  CET_FLAGS="-fcf-protection -mcet"
+fi
+
+
+
 # Check whether --enable-explicit-exception-frame-registration was given.
 if test "${enable_explicit_exception_frame_registration+set}" = set; then :
   enableval=$enable_explicit_exception_frame_registration;