diff mbox series

[RFC,v4,13/42] kmsan: define READ_ONCE_NOCHECK()

Message ID 20191220184955.223741-14-glider@google.com (mailing list archive)
State New, archived
Headers show
Series Add KernelMemorySanitizer infrastructure | expand

Commit Message

Alexander Potapenko Dec. 20, 2019, 6:49 p.m. UTC 
READ_ONCE_NOCHECK() is already used by KASAN to ignore memory accesses
from e.g. stack unwinders.
Define READ_ONCE_NOCHECK() for KMSAN so that it returns initialized
values. This helps defeat false positives from leftover stack contents.

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: linux-mm@kvack.org
---
v3:
 - removed unnecessary #ifdef as requested by Mark Rutland
v4:
 - added an #include as requested by Marco Elver

Change-Id: Ib38369ba038ab3b581d8e45b81036c3304fb79cb
---
 include/linux/compiler.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 5e88e7e33abe..de7942423836 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -255,6 +255,7 @@  static __always_inline void __write_once_size(volatile void *p, void *res, int s
  */
 #include <asm/barrier.h>
 #include <linux/kasan-checks.h>
+#include <linux/kmsan-checks.h>
 
 #define __READ_ONCE(x, check)						\
 ({									\
@@ -270,9 +271,9 @@  static __always_inline void __write_once_size(volatile void *p, void *res, int s
 
 /*
  * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
- * to hide memory access from KASAN.
+ * to hide memory access from KASAN or KMSAN.
  */
-#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
+#define READ_ONCE_NOCHECK(x) KMSAN_INIT_VALUE(__READ_ONCE(x, 0))
 
 static __no_kasan_or_inline
 unsigned long read_word_at_a_time(const void *addr)