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

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Message-ID: <YrGhkSt/tYF1H84v@arm.com>
Date:   Tue, 21 Jun 2022 11:46:41 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     elver@...gle.com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        mark.rutland@....com, Jonathan Corbet <corbet@....net>,
        linux-doc@...r.kernel.org, arnd@...db.de
Subject: Re: [PATCH v4 2/2] arm64: kcsan: Support detecting more missing
 memory barriers

On Mon, May 23, 2022 at 07:31:26PM +0800, Kefeng Wang wrote:
> 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>

Acked-by: Catalin Marinas <catalin.marinas@....com>

I'll leave the series to Will to queue for 5.20.

Thanks.

-- 
Catalin