support Spectre mitigation patch for gcc compiler

1 files changed, 20 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 952dec3b8..d6d4eb874 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,6 +9,24 @@ AC_PROG_CC
 AC_PROG_INSTALL
 AC_PROG_RANLIB
 
+
+HAVE_SPECTRE="no"
+AC_MSG_CHECKING(for Spectre mitigation support in gcc compiler)
+AS_IF([test "$CC" = "gcc"], [
+        HAVE_SPECTRE="yes"
+        $CC -mindirect-branch=thunk -c dummy.c || HAVE_SPECTRE="no"
+        rm -f dummy.o
+])
+AS_IF([test "$HAVE_SPECTRE" = "yes"], [
+        AC_MSG_RESULT(yes)
+        EXTRA_CFLAGS+="-mindirect-branch=thunk"
+])
+AS_IF([test "$HAVE_SPECTRE" = "no"], [
+        AC_MSG_RESULT(... not available)
+])
+AC_SUBST([EXTRA_CFLAGS])
+
+
 HAVE_APPARMOR=""
 AC_ARG_ENABLE([apparmor],
     AS_HELP_STRING([--enable-apparmor], [enable apparmor]))
@@ -198,7 +216,9 @@ echo "   file transfer support: $HAVE_FILE_TRANSFER"
 echo "   overlayfs support: $HAVE_OVERLAYFS"
 echo "   git install support: $HAVE_GIT_INSTALL"
 echo "   busybox workaround: $BUSYBOX_WORKAROUND"
+echo "   Spectre compiler patch: $HAVE_SPECTRE"
 echo "   EXTRA_LDFLAGS: $EXTRA_LDFLAGS"
+echo "   EXTRA_CFLAGS: $EXTRA_CFLAGS"
 echo "   fatal warnings: $HAVE_FATAL_WARNINGS"
 echo "   Gcov instrumentation: $HAVE_GCOV"
 echo "   Install contrib scripts: $HAVE_CONTRIB_INSTALL"