From: codarrenvelvindron <codarren@hackers.mu>
Date: Sat, 17 Feb 2018 19:28:48 +0000 (-0500)
Subject: configure: Add spectre variant 2 mitigations
X-Git-Tag: 2.3.9~2220
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=60b67403d7fe4d6f44f62d8ec8bb890345245024;p=thirdparty%2Fdovecot%2Fcore.git

configure: Add spectre variant 2 mitigations

--enable-hardening adds -mfunction-return=thunk and -mindirect-branch=thunk
compiler options if supported.
---

diff --git a/configure.ac b/configure.ac
index 10543fa929..46ea4bcfd7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -321,6 +321,7 @@ CC_CLANG
 AC_CC_PIE
 AC_CC_F_STACK_PROTECTOR
 AC_CC_D_FORTIFY_SOURCE
+AC_CC_RETPOLINE
 AC_LD_RELRO
 AC_LD_WHOLE_ARCHIVE
 
diff --git a/m4/cc_retpoline.m4 b/m4/cc_retpoline.m4
new file mode 100644
index 0000000000..26f567c3a1
--- /dev/null
+++ b/m4/cc_retpoline.m4
@@ -0,0 +1,18 @@
+dnl
+dnl Check for support for Retpoline
+dnl
+
+AC_DEFUN([AC_CC_RETPOLINE],[
+    AC_REQUIRE([gl_UNKNOWN_WARNINGS_ARE_ERRORS])
+    if test $enable_hardening = yes; then
+      case "$host" in
+        *)
+          gl_COMPILER_OPTION_IF([-mfunction-return=thunk -mindirect-branch=thunk], [
+            CFLAGS="$CFLAGS -mfunction-return=thunk -mindirect-branch=thunk"
+            ],
+            [],
+            [AC_LANG_PROGRAM()]
+          )
+      esac
+    fi
+])