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 5F303C433EF for ; Tue, 26 Apr 2022 15:36:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352390AbiDZPjJ (ORCPT ); Tue, 26 Apr 2022 11:39:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346484AbiDZPjI (ORCPT ); Tue, 26 Apr 2022 11:39:08 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32B1EFD25 for ; Tue, 26 Apr 2022 08:35:59 -0700 (PDT) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Knljt5KSfzfb9P; Tue, 26 Apr 2022 23:12:34 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 26 Apr 2022 23:13:27 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 26 Apr 2022 23:13:27 +0800 Message-ID: <4c8acff0-38c5-4a4e-e216-c5252259b1f8@huawei.com> Date: Tue, 26 Apr 2022 23:13:27 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH] arm64: kcsan: Fix kcsan test_barrier fail and panic Content-Language: en-US To: Marco Elver CC: , , , , References: <20220426081700.1376542-1-wangkefeng.wang@huawei.com> From: Kefeng Wang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/4/26 20:10, Marco Elver wrote: > On Tue, Apr 26, 2022 at 08:17AM +0000, Kefeng Wang wrote: >> As "kcsan: Support detecting a subset of missing memory barriers" >> introduced KCSAN_STRICT which make kcsan detects more missing memory >> barrier, but arm64 don't have KCSAN instrumentation for barriers, so >> the new selftest test_barrier() will fail, then panic. > Thanks for fixing this - did kcsan_test module pass as well? Yes， selftest and kcsan_test  passed with gcc11 & clang 14. ... >> +#ifdef __dma_mb >> +#define dma_mb() do { kcsan_mb(); __dma_mb(); } while (0) >> +#endif >> + > So it looks like arm64 is the only arch that defines dma_mb(). By adding > it to asm-generic, we'd almost be encouraging other architectures to add > it, which I don't know we want. > > Documentation/memory-barriers.txt doesn't mention dma_mb() either - so > perhaps dma_mb() doesn't belong in asm-generic/barrier.h, and you could > only change arm64's definition of dma_mb() to add the kcsan_mb(). > > Preferences? Maybe arch64 maintainers have more background on why arm64 > is an anomaly here. > . Let's wait to see aarch64 maintainers's suggestion.