1 files changed, 4 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 0476398ac..71174571b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -163,6 +163,10 @@ if test "$GCC" = "yes" || test "$GCC" = "egcs"; then
         OSSH_CHECK_CFLAG_COMPILE([-Wunused-result], [-Wno-unused-result])
         OSSH_CHECK_CFLAG_COMPILE([-fno-strict-aliasing])
     if test "x$use_toolchain_hardening" = "x1"; then
+        OSSH_CHECK_CFLAG_COMPILE([-mfunction-return=thunk]) # gcc
+        OSSH_CHECK_CFLAG_COMPILE([-mindirect-branch=thunk]) # gcc
+        OSSH_CHECK_CFLAG_COMPILE([-mretpoline]) # clang
+        OSSH_CHECK_CFLAG_LINK([-z retpolineplt])
         OSSH_CHECK_CFLAG_COMPILE([-D_FORTIFY_SOURCE=2])
         OSSH_CHECK_LDFLAG_LINK([-Wl,-z,relro])
         OSSH_CHECK_LDFLAG_LINK([-Wl,-z,now])