kmsan: expose KMSAN_WARN_ON()

KMSAN_WARN_ON() is required for implementing s390-specific KMSAN
functions, but right now it's available only to the KMSAN internal
functions. Expose it to subsystems through <linux/kmsan.h>.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ilya Leoshkevich <[e-mail]>
Reviewed-by: Alexander Potapenko <[e-mail]>
Cc: Alexander Gordeev <[e-mail]>
Cc: Christian Borntraeger <[e-mail]>
Cc: Christoph Lameter <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: Dmitry Vyukov <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Hyeonggon Yoo <[e-mail]>
Cc: Joonsoo Kim <[e-mail]>
Cc: <[e-mail]>
Cc: Marco Elver <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Masami Hiramatsu (Google) <[e-mail]>
Cc: Pekka Enberg <[e-mail]>
Cc: Roman Gushchin <[e-mail]>
Cc: Steven Rostedt (Google) <[e-mail]>
Cc: Sven Schnelle <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

include/linux/kmsan.h

···
 	return __memset(s, c, n);
 }
 
+extern bool kmsan_enabled;
+extern int panic_on_kmsan;
+
+/*
+ * KMSAN performs a lot of consistency checks that are currently enabled by
+ * default. BUG_ON is normally discouraged in the kernel, unless used for
+ * debugging, but KMSAN itself is a debugging tool, so it makes little sense to
+ * recover if something goes wrong.
+ */
+#define KMSAN_WARN_ON(cond)                                           \
+	({                                                            \
+		const bool __cond = WARN_ON(cond);                    \
+		if (unlikely(__cond)) {                               \
+			WRITE_ONCE(kmsan_enabled, false);             \
+			if (panic_on_kmsan) {                         \
+				/* Can't call panic() here because */ \
+				/* of uaccess checks. */              \
+				BUG();                                \
+			}                                             \
+		}                                                     \
+		__cond;                                               \
+	})
+
 #else
 
 static inline void kmsan_init_shadow(void)
···
 {
 	return memset(s, c, n);
 }
+
+#define KMSAN_WARN_ON WARN_ON
 
 #endif
 

mm/kmsan/kmsan.h

···
 #define __MM_KMSAN_KMSAN_H
 
 #include <linux/irqflags.h>
+#include <linux/kmsan.h>
 #include <linux/mm.h>
 #include <linux/nmi.h>
 #include <linux/pgtable.h>
···
 
 #define KMSAN_META_SHADOW (false)
 #define KMSAN_META_ORIGIN (true)
-
-extern bool kmsan_enabled;
-extern int panic_on_kmsan;
-
-/*
- * KMSAN performs a lot of consistency checks that are currently enabled by
- * default. BUG_ON is normally discouraged in the kernel, unless used for
- * debugging, but KMSAN itself is a debugging tool, so it makes little sense to
- * recover if something goes wrong.
- */
-#define KMSAN_WARN_ON(cond)                                           \
-	({                                                            \
-		const bool __cond = WARN_ON(cond);                    \
-		if (unlikely(__cond)) {                               \
-			WRITE_ONCE(kmsan_enabled, false);             \
-			if (panic_on_kmsan) {                         \
-				/* Can't call panic() here because */ \
-				/* of uaccess checks. */              \
-				BUG();                                \
-			}                                             \
-		}                                                     \
-		__cond;                                               \
-	})
 
 /*
  * A pair of metadata pointers to be returned by the instrumentation functions.