The following commit has been merged into the locking/kcsan branch of tip:
Commit-ID: 777f73c4e79106d45b304f6af0d31917864dbdf1
Gitweb:
https://git.kernel.org/tip/777f73c4e79106d45b304f6af0d31917864dbdf1
Author: Marco Elver <[email protected]>
AuthorDate: Thu, 21 May 2020 16:20:44 +02:00
Committer: Borislav Petkov <[email protected]>
CommitterDate: Fri, 22 May 2020 15:19:53 +02:00
compiler.h: Remove data_race() and unnecessary checks from {READ,WRITE}_ONCE()
The volatile accesses no longer need to be wrapped in data_race()
because compilers that emit instrumentation distinguishing volatile
accesses are required for KCSAN.
Consequently, the explicit kcsan_check_atomic*() are no longer required
either since the compiler emits instrumentation distinguishing the
volatile accesses.
Finally, simplify __READ_ONCE_SCALAR() and remove __WRITE_ONCE_SCALAR().
[ bp: Convert commit message to passive voice. ]
Signed-off-by: Marco Elver <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Will Deacon <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
---
include/linux/compiler.h | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 17c98b2..7444f02 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -228,9 +228,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int
val,
#define __READ_ONCE_SCALAR(x) \
({ \
- typeof(x) *__xp = &(x); \
- __unqual_scalar_typeof(x) __x = data_race(__READ_ONCE(*__xp)); \
- kcsan_check_atomic_read(__xp, sizeof(*__xp)); \
+ __unqual_scalar_typeof(x) __x = __READ_ONCE(x); \
smp_read_barrier_depends(); \
(typeof(x))__x; \
})
@@ -246,17 +244,10 @@ do {
\
*(volatile typeof(x) *)&(x) = (val); \
} while (0)
-#define __WRITE_ONCE_SCALAR(x, val) \
-do { \
- typeof(x) *__xp = &(x); \
- kcsan_check_atomic_write(__xp, sizeof(*__xp)); \
- data_race(({ __WRITE_ONCE(*__xp, val); 0; })); \
-} while (0)
-
#define WRITE_ONCE(x, val) \
do { \
compiletime_assert_rwonce_type(x); \
- __WRITE_ONCE_SCALAR(x, val); \
+ __WRITE_ONCE(x, val); \
} while (0)
#ifdef CONFIG_KASAN
