Check whether -fcf-protection=none -Wl,-z,ibt,-z,shstk work first

GCC_CET_HOST_FLAGS uses -Wl,-z,ibt,-z,shstk to check if Linux/x86 host
has Intel CET enabled by introducing an Intel CET violation on purpose.
To avoid false positive, check whether -Wl,-z,ibt,-z,shstk works first.
-fcf-protection=none is added to avoid false negative when -fcf-protection
is enabled by default.

config/

	PR bootstrap/94739
	* cet.m4 (GCC_CET_HOST_FLAGS): Add -fcf-protection=none to
	-Wl,-z,ibt,-z,shstk.  Check whether -fcf-protection=none
	-Wl,-z,ibt,-z,shstk works first.

libiberty/

	PR bootstrap/94739
	* configure: Regenerated.

lto-plugin/

	PR bootstrap/94739
	* configure: Regenerated.

config/ChangeLog

@@ -1,3 +1,10 @@
+2020-04-28  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR bootstrap/94739
+	* cet.m4 (GCC_CET_HOST_FLAGS): Add -fcf-protection=none to
+	-Wl,-z,ibt,-z,shstk.  Check whether -fcf-protection=none
+	-Wl,-z,ibt,-z,shstk works first.
+
 2020-04-25  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR bootstrap/94739

config/cet.m4

@@ -98,9 +98,19 @@ asm ("setssbsy");
     ;;
 esac
 
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -fcf-protection=none"
+save_LDFLAGS="$LDFLAGS"
+LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
+if test x$may_have_cet = xyes; then
+  # Check whether -fcf-protection=none -Wl,-z,ibt,-z,shstk work.
+  AC_TRY_LINK(
+    [],[return 0;],
+    [may_have_cet=yes],
+    [may_have_cet=no])
+fi
+
 if test x$may_have_cet = xyes; then
-  save_LDFLAGS="$LDFLAGS"
-  LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
   AC_TRY_RUN([
 static void
 foo (void)
@@ -130,7 +140,6 @@ main ()
   ],
   [have_cet=no],
   [have_cet=yes])
-  LDFLAGS="$save_LDFLAGS"
   if test x$enable_cet = xno -a x$have_cet = xyes; then
     AC_MSG_ERROR([Intel CET must be enabled on Intel CET enabled host])
   fi
@@ -141,4 +150,6 @@ if test x$enable_cet = xyes; then
 else
   AC_MSG_RESULT([no])
 fi
+CFLAGS="$save_CFLAGS"
+LDFLAGS="$save_LDFLAGS"
 ])

libiberty/ChangeLog

@@ -1,3 +1,8 @@
+2020-04-28  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR bootstrap/94739
+	* configure: Regenerated.
+
 2020-04-27  Jakub Jelinek  <jakub@redhat.com>
 
 	PR demangler/94797

libiberty/configure

@@ -1674,6 +1674,52 @@ $as_echo "$ac_res" >&6; }
 
 } # ac_fn_c_check_header_compile
 
+# ac_fn_c_try_link LINENO
+# -----------------------
+# Try to link conftest.$ac_ext, and return whether this succeeded.
+ac_fn_c_try_link ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  rm -f conftest.$ac_objext conftest$ac_exeext
+  if { { ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
+$as_echo "$ac_try_echo"; } >&5
+  (eval "$ac_link") 2>conftest.err
+  ac_status=$?
+  if test -s conftest.err; then
+    grep -v '^ *+' conftest.err >conftest.er1
+    cat conftest.er1 >&5
+    mv -f conftest.er1 conftest.err
+  fi
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest$ac_exeext && {
+	 test "$cross_compiling" = yes ||
+	 test -x conftest$ac_exeext
+       }; then :
+  ac_retval=0
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_retval=1
+fi
+  # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information
+  # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would
+  # interfere with the next link command; also delete a directory that is
+  # left behind by Apple's compiler.  We do this before executing the actions.
+  rm -rf conftest.dSYM conftest_ipa8_conftest.oo
+  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
+  as_fn_set_status $ac_retval
+
+} # ac_fn_c_try_link
+
 # ac_fn_c_check_header_preproc LINENO HEADER VAR
 # ----------------------------------------------
 # Tests whether HEADER is present, setting the cache variable VAR accordingly.
@@ -1940,52 +1986,6 @@ $as_echo "$ac_res" >&6; }
 
 } # ac_fn_c_check_type
 
-# ac_fn_c_try_link LINENO
-# -----------------------
-# Try to link conftest.$ac_ext, and return whether this succeeded.
-ac_fn_c_try_link ()
-{
-  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
-  rm -f conftest.$ac_objext conftest$ac_exeext
-  if { { ac_try="$ac_link"
-case "(($ac_try" in
-  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
-  *) ac_try_echo=$ac_try;;
-esac
-eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
-$as_echo "$ac_try_echo"; } >&5
-  (eval "$ac_link") 2>conftest.err
-  ac_status=$?
-  if test -s conftest.err; then
-    grep -v '^ *+' conftest.err >conftest.er1
-    cat conftest.er1 >&5
-    mv -f conftest.er1 conftest.err
-  fi
-  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
-  test $ac_status = 0; } && {
-	 test -z "$ac_c_werror_flag" ||
-	 test ! -s conftest.err
-       } && test -s conftest$ac_exeext && {
-	 test "$cross_compiling" = yes ||
-	 test -x conftest$ac_exeext
-       }; then :
-  ac_retval=0
-else
-  $as_echo "$as_me: failed program was:" >&5
-sed 's/^/| /' conftest.$ac_ext >&5
-
-	ac_retval=1
-fi
-  # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information
-  # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would
-  # interfere with the next link command; also delete a directory that is
-  # left behind by Apple's compiler.  We do this before executing the actions.
-  rm -rf conftest.dSYM conftest_ipa8_conftest.oo
-  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
-  as_fn_set_status $ac_retval
-
-} # ac_fn_c_try_link
-
 # ac_fn_c_check_func LINENO FUNC VAR
 # ----------------------------------
 # Tests whether FUNC exists, setting the cache variable VAR accordingly
@@ -5345,9 +5345,36 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
     ;;
 esac
 
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -fcf-protection=none"
+save_LDFLAGS="$LDFLAGS"
+LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
+if test x$may_have_cet = xyes; then
+  # Check whether -fcf-protection=none -Wl,-z,ibt,-z,shstk work.
+  if test x$gcc_no_link = xyes; then
+  as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
+fi
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  may_have_cet=yes
+else
+  may_have_cet=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+
 if test x$may_have_cet = xyes; then
-  save_LDFLAGS="$LDFLAGS"
-  LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
   if test "$cross_compiling" = yes; then :
   { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
 $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
@@ -5393,7 +5420,6 @@ rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
   conftest.$ac_objext conftest.beam conftest.$ac_ext
 fi
 
-  LDFLAGS="$save_LDFLAGS"
   if test x$enable_cet = xno -a x$have_cet = xyes; then
     as_fn_error $? "Intel CET must be enabled on Intel CET enabled host" "$LINENO" 5
   fi
@@ -5406,6 +5432,8 @@ else
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 fi
+CFLAGS="$save_CFLAGS"
+LDFLAGS="$save_LDFLAGS"
 
 
 

lto-plugin/ChangeLog

@@ -1,3 +1,8 @@
+2020-04-28  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR bootstrap/94739
+	* configure: Regenerated.
+
 2020-04-25  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR bootstrap/94739

lto-plugin/configure

@@ -5741,9 +5741,33 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
     ;;
 esac
 
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -fcf-protection=none"
+save_LDFLAGS="$LDFLAGS"
+LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
+if test x$may_have_cet = xyes; then
+  # Check whether -fcf-protection=none -Wl,-z,ibt,-z,shstk work.
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  may_have_cet=yes
+else
+  may_have_cet=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+
 if test x$may_have_cet = xyes; then
-  save_LDFLAGS="$LDFLAGS"
-  LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
   if test "$cross_compiling" = yes; then :
   { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
 $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
@@ -5789,7 +5813,6 @@ rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
   conftest.$ac_objext conftest.beam conftest.$ac_ext
 fi
 
-  LDFLAGS="$save_LDFLAGS"
   if test x$enable_cet = xno -a x$have_cet = xyes; then
     as_fn_error $? "Intel CET must be enabled on Intel CET enabled host" "$LINENO" 5
   fi
@@ -5802,6 +5825,8 @@ else
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 fi
+CFLAGS="$save_CFLAGS"
+LDFLAGS="$save_LDFLAGS"
 
 
 
@@ -11916,7 +11941,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11919 "configure"
+#line 11944 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12022,7 +12047,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12025 "configure"
+#line 12050 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H