linux-kernel - [PATCH v4 2/2] arm64: kcsan: Support detecting more missing memory barriers

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Date:   Mon, 23 May 2022 19:31:26 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     <elver@...gle.com>, <catalin.marinas@....com>, <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <mark.rutland@....com>,
        Jonathan Corbet <corbet@....net>
CC:     <linux-doc@...r.kernel.org>, <arnd@...db.de>,
        Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: [PATCH v4 2/2] arm64: kcsan: Support detecting more missing memory barriers

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/

Acked-by: Marco Elver <elver@...gle.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 arch/arm64/include/asm/barrier.h | 12 ++++++------
 1 file changed, 6 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()

-- 
2.35.3