From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38555C433F5 for ; Mon, 23 May 2022 14:18:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237068AbiEWOSU (ORCPT ); Mon, 23 May 2022 10:18:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237054AbiEWOSQ (ORCPT ); Mon, 23 May 2022 10:18:16 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 465215A088; Mon, 23 May 2022 07:18:15 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AAC7D1063; Mon, 23 May 2022 07:18:14 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.9.63]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0904A3F70D; Mon, 23 May 2022 07:18:12 -0700 (PDT) Date: Mon, 23 May 2022 15:16:35 +0100 From: Mark Rutland To: Kefeng Wang Cc: elver@google.com, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jonathan Corbet , linux-doc@vger.kernel.org, arnd@arndb.de Subject: Re: [PATCH v4 2/2] arm64: kcsan: Support detecting more missing memory barriers Message-ID: References: <20220523113126.171714-1-wangkefeng.wang@huawei.com> <20220523113126.171714-3-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220523113126.171714-3-wangkefeng.wang@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org 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 > Signed-off-by: Kefeng Wang Having built this with GCC 12.1.0 and LLVM 14.0.0, I think this patch itself doesn't introduce any new problems, and logically makes sense. With that in mind: Acked-by: Mark Rutland As an aside, having scanned the resulting vmlinux with objdump, there are plenty of latent issues where we get KCSAN instrumentation where we don't want it (e.g. early/late in arm64's entry-common.o). The bulk of those are due to missing `nonistr` or `__always_inline`, which we'll need to fix up. Thanks, Mark. > --- > 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 >