[PATCH v2 2/2] arm64: kcsan: Support detecting more missing memory barriers

[Kefeng Wang]

As "kcsan: Support detecting a subset of missing memory barriers"[1]
introduced KCSAN_STRICT/KCSAN_WEAK_MEMORY which make kcsan detects
more missing memory barrier, but arm64 don't have KCSAN instrumentation
for barriers, so the new selftest test_barrier() and test cases for
memory barrier instrumentation in kcsan_test module will fail, even
panic on selftest.

Let's prefix all barriers with __ on arm64, as asm-generic/barriers.h
defined the final instrumented version of these barriers, which will
fix the above issues.

Note, barrier instrumentation that can be disabled via __no_kcsan with
appropriate compiler-support (and not just with objtool help), see
commit bd3d5bd1a0ad ("kcsan: Support WEAK_MEMORY with Clang where no
objtool support exists"), it adds disable_sanitizer_instrumentation to
__no_kcsan attribute which will remove all sanitizer instrumentation fully
(with Clang 14.0). Meanwhile, GCC does the same thing with no_sanitize.

[1] https://lore.kernel.org/linux-mm/20211130114433.2580590-1-elver@google.com/
Signed-off-by: Kefeng Wang <wangkefeng.wang at huawei.com>
---
 arch/arm64/include/asm/barrier.h | 12 ++++++------
 include/asm-generic/barrier.h    |  4 ++++
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 9f3e2c3d2ca0..2cfc4245d2e2 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -50,13 +50,13 @@
 #define pmr_sync()	do {} while (0)
 #endif
 
-#define mb()		dsb(sy)
-#define rmb()		dsb(ld)
-#define wmb()		dsb(st)
+#define __mb()		dsb(sy)
+#define __rmb()		dsb(ld)
+#define __wmb()		dsb(st)
 
-#define dma_mb()	dmb(osh)
-#define dma_rmb()	dmb(oshld)
-#define dma_wmb()	dmb(oshst)
+#define __dma_mb()	dmb(osh)
+#define __dma_rmb()	dmb(oshld)
+#define __dma_wmb()	dmb(oshst)
 
 #define io_stop_wc()	dgh()
 
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index fd7e8fbaeef1..18863c50e9ce 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -38,6 +38,10 @@
 #define wmb()	do { kcsan_wmb(); __wmb(); } while (0)
 #endif
 
+#ifdef __dma_mb
+#define dma_mb()	do { kcsan_mb(); __dma_mb(); } while (0)
+#endif
+
 #ifdef __dma_rmb
 #define dma_rmb()	do { kcsan_rmb(); __dma_rmb(); } while (0)
 #endif
-- 
2.35.3