header: nospec.h: provide dummy header file

Older kernel versions do not have the include linux/nospec.h with the
function array_index_nospec, provide a dummy implementation for these
kernel versions and forward the call the the real version for capable
kernel versions.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/backport/backport-include/linux/nospec.h b/backport/backport-include/linux/nospec.h
new file mode 100644 (file)
index 0000000..50cf467
--- /dev/null
+++ b/backport/backport-include/linux/nospec.h
@@ -0,0 +1,12 @@
+#ifndef _BACKPORT_LINUX_NOSPEC_H
+#define _BACKPORT_LINUX_NOSPEC_H
+
+#if LINUX_VERSION_IS_GEQ(4,14,18) || \
+    LINUX_VERSION_IN_RANGE(4,9,81, 4,10,0) || \
+    LINUX_VERSION_IN_RANGE(4,4,118, 4,5,0)
+#include_next <linux/nospec.h>
+#else
+#define array_index_nospec(index, size)        (index)
+#endif
+
+#endif /* _BACKPORT_LINUX_NOSPEC_H */