add support for clang Control Flow Integrity (CFI)

This change adds the CONFIG_CFI_CLANG option, CFI error handling,
and a faster look-up table for cross module CFI checks.

Bug: 67506682
Change-Id: Ic009f0a629b552a0eb16e6d89808c7029e91447d
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

include/linux/module.h

@@ -20,6 +20,7 @@
 #include <linux/export.h>
 #include <linux/extable.h>	/* only as arch move module.h -> extable.h */
 #include <linux/rbtree_latch.h>
+#include <linux/cfi.h>
 
 #include <linux/percpu.h>
 #include <asm/module.h>
@@ -349,6 +350,10 @@ struct module {
 	const unsigned long *crcs;
 	unsigned int num_syms;
 
+#ifdef CONFIG_CFI_CLANG
+	cfi_check_fn cfi_check;
+#endif
+
 	/* Kernel parameters. */
 #ifdef CONFIG_SYSFS
 	struct mutex param_lock;