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 X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E855FC433E6 for ; Wed, 13 Jan 2021 16:23:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95AAB235F9 for ; Wed, 13 Jan 2021 16:23:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727773AbhAMQXN (ORCPT ); Wed, 13 Jan 2021 11:23:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33748 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727748AbhAMQXL (ORCPT ); Wed, 13 Jan 2021 11:23:11 -0500 Received: from mail-qk1-x74a.google.com (mail-qk1-x74a.google.com [IPv6:2607:f8b0:4864:20::74a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C1E0C0617A5 for ; Wed, 13 Jan 2021 08:22:06 -0800 (PST) Received: by mail-qk1-x74a.google.com with SMTP id k126so1716945qkf.8 for ; Wed, 13 Jan 2021 08:22:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=1ElsZsJrO3cOsYp/vFzZufoQKn9+sd3vP1RO0nASQZ0=; b=vLdGASrWREAy+wj9sfLUQB8j+yuVmoSbMdRaRJXHZRPSwkP8jB8knKlgUr+3AQR9Ve +r4vu4nQaMgAPKzfyhmAnJD0GwU6xEzluvKdeR9lktNoMnhyjqR2SbxVWzWiTKW3yd8A dxzNhIdB5+2+uFtg8x0VySNNDiMNMTODEvZz/GwlMWaIXxmHrfBNWrul1YExWcwZe8dq ErFPQ5XWd+oRZYvm3QY1ynahqe5O0lzPJ4CWD5ZbJ02KeB2Jlc94Cg++JguL9yPQXGhb Dnm7IxJww7M1CbKv0pids9Wc5g1KRkXybcD1YhSQUrQhlRSOZpo13kWx8rJLimwmCi4/ gOhA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=1ElsZsJrO3cOsYp/vFzZufoQKn9+sd3vP1RO0nASQZ0=; b=Ts3svAeKDJDlpxIdt26CFilp9foMqW7JrtIV9BDQNpUp0gAbq3ktvnCdbpXRwNsiMs UXCCwvI6h60j6XrHkBTdvU6wEkyBUNI+TtctiTU2c0nOBfvPUm66yClHov+MTmt9bVMY xUjQqY2omIuSpKra6WqGctXLEVzPhkpjjbDkgORvl8bb/0UlP5G9JO2bmMg0x7veE8kT /AyanUHWLx/Zh58D/WQSBp9CNq5lNjJ9pDDUI08ei659ruXYUdg78EglAh4Z9kWR8AQF ZE6bY/bxzWtOxu7dESMrMB8nEfCpXhckueEm3+TGDFMT2FRxEpLXRLBiCfnTH1NZ6iHK 1mlg== X-Gm-Message-State: AOAM531AcudR9vG40Ix2zQV9c0u71SPuWWHoAUs+Zv1dvuWXmySFAmFH nFaX2Hm57xAk1s9H9xW9HpO3DVNuFj3nDS4R X-Google-Smtp-Source: ABdhPJzRVpbzs6eSZ4YpS+Iv4DdXN1T6DSp2/3sND1u+wQPzWYQWt3sUVkNPSbg16ucwUAEsnMF3mPkHaU9ACJ77 Sender: "andreyknvl via sendgmr" X-Received: from andreyknvl3.muc.corp.google.com ([2a00:79e0:15:13:7220:84ff:fe09:7e9d]) (user=andreyknvl job=sendgmr) by 2002:a0c:fd89:: with SMTP id p9mr3153133qvr.8.1610554925220; Wed, 13 Jan 2021 08:22:05 -0800 (PST) Date: Wed, 13 Jan 2021 17:21:35 +0100 In-Reply-To: Message-Id: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.30.0.284.gd98b1dd5eaa7-goog Subject: [PATCH v2 08/14] kasan: add compiler barriers to KUNIT_EXPECT_KASAN_FAIL From: Andrey Konovalov To: Catalin Marinas , Vincenzo Frascino , Dmitry Vyukov , Alexander Potapenko , Marco Elver Cc: Andrew Morton , Will Deacon , Andrey Ryabinin , Peter Collingbourne , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It might not be obvious to the compiler that the expression must be executed between writing and reading to fail_data. In this case, the compiler might reorder or optimize away some of the accesses, and the tests will fail. Add compiler barriers around the expression in KUNIT_EXPECT_KASAN_FAIL and use READ/WRITE_ONCE() for accessing fail_data fields. Link: https://linux-review.googlesource.com/id/I046079f48641a1d36fe627fc8827a9249102fd50 Signed-off-by: Andrey Konovalov --- lib/test_kasan.c | 17 ++++++++++++----- mm/kasan/report.c | 2 +- 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 5c8aa3a5ce93..283feda9882a 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -68,23 +68,30 @@ static void kasan_test_exit(struct kunit *test) * normally auto-disabled. When this happens, this test handler reenables * tag checking. As tag checking can be only disabled or enabled per CPU, this * handler disables migration (preemption). + * + * Since the compiler doesn't see that the expression can change the fail_data + * fields, it can reorder or optimize away the accesses to those fields. + * Use READ/WRITE_ONCE() for the accesses and compiler barriers around the + * expression to prevent that. */ #define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \ if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) \ migrate_disable(); \ - fail_data.report_expected = true; \ - fail_data.report_found = false; \ + WRITE_ONCE(fail_data.report_expected, true); \ + WRITE_ONCE(fail_data.report_found, false); \ kunit_add_named_resource(test, \ NULL, \ NULL, \ &resource, \ "kasan_data", &fail_data); \ + barrier(); \ expression; \ + barrier(); \ KUNIT_EXPECT_EQ(test, \ - fail_data.report_expected, \ - fail_data.report_found); \ + READ_ONCE(fail_data.report_expected), \ + READ_ONCE(fail_data.report_found)); \ if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \ - if (fail_data.report_found) \ + if (READ_ONCE(fail_data.report_found)) \ hw_enable_tagging(); \ migrate_enable(); \ } \ diff --git a/mm/kasan/report.c b/mm/kasan/report.c index e93d7973792e..234f35a84f19 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -331,7 +331,7 @@ static void kasan_update_kunit_status(struct kunit *cur_test) } kasan_data = (struct kunit_kasan_expectation *)resource->data; - kasan_data->report_found = true; + WRITE_ONCE(kasan_data->report_found, true); kunit_put_resource(resource); } #endif /* IS_ENABLED(CONFIG_KUNIT) */ -- 2.30.0.284.gd98b1dd5eaa7-goog