1 files changed, 5 insertions, 1 deletions

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index c8bd2daf95ec..98115d9d04da 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -44,6 +44,8 @@ extern void __chk_io_ptr(const volatile void __iomem *);
 # error Sorry, your compiler is too old/not recognized.
 #endif
 
+#define notrace __attribute__((no_instrument_function))
+
 /* Intel compiler defines __GNUC__. So we will overwrite implementations
  * coming from above header files here
  */
@@ -190,7 +192,9 @@ extern void __chk_io_ptr(const volatile void __iomem *);
  * ACCESS_ONCE() in different C statements.
  *
  * This macro does absolutely -nothing- to prevent the CPU from reordering,
- * merging, or refetching absolutely anything at any time.
+ * merging, or refetching absolutely anything at any time.  Its main intended
+ * use is to mediate communication between process-level code and irq/NMI
+ * handlers, all running on the same CPU.
  */
 #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))