x86, kcsan: Add __no_kcsan to noinstr

The 'noinstr' function attribute means no-instrumentation, this should
very much include *SAN. Because lots of that is broken at present,
only include KCSAN for now, as that is limited to clang11, which has
sane function attribute behaviour.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

include/linux/compiler_types.h

@@ -118,10 +118,6 @@ struct ftrace_likely_data {
 #define notrace			__attribute__((__no_instrument_function__))
 #endif
 
-/* Section for code which can't be instrumented at all */
-#define noinstr								\
-	noinline notrace __attribute((__section__(".noinstr.text")))
-
 /*
  * it doesn't make sense on ARM (currently the only user of __naked)
  * to trace naked functions because then mcount is called without
@@ -200,6 +196,10 @@ struct ftrace_likely_data {
 #define __no_sanitize_or_inline __always_inline
 #endif
 
+/* Section for code which can't be instrumented at all */
+#define noinstr								\
+	noinline notrace __attribute((__section__(".noinstr.text"))) __no_kcsan
+
 #endif /* __KERNEL__ */
 
 #endif /* __ASSEMBLY__ */