From nobody Thu Sep 18 15:37:40 2025 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 7EDEDC4321E for ; Mon, 5 Dec 2022 14:57:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231265AbiLEO5v (ORCPT ); Mon, 5 Dec 2022 09:57:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230000AbiLEO5r (ORCPT ); Mon, 5 Dec 2022 09:57:47 -0500 Received: from mail-ej1-x64a.google.com (mail-ej1-x64a.google.com [IPv6:2a00:1450:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC1AA5F87 for ; Mon, 5 Dec 2022 06:57:45 -0800 (PST) Received: by mail-ej1-x64a.google.com with SMTP id nc4-20020a1709071c0400b0078a5ceb571bso7551980ejc.4 for ; Mon, 05 Dec 2022 06:57:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=YAXOrsESrx0CdS4Q6xjLBDZXEnUh9Z0PdR9s8BvDppo=; b=ql5DAtYvnEvQAuv1Vg7O2uFk4TDOneX6PiWFdn5sm1InzCNwvuD+TNu80xbOhaLWHW Kvk1qtNKOg8fKGE3QXew2wXaYc8ycPvXrANWjCCd6ex5xA+DB3Y5q93zNpwpOls2gwld anNWOtm9lLhQZOroxXTd+g4keYF1LDsVuM7xDLI06sS0v/Y5oGzPWdxHKHKRCV2ChM9O uBPzDJ6wPAse5H7pHJZ7TKkYMa6hIxfPSxJE7VK9spAx121eufzZ7nwsvX6Y0rub+P4D S2z1c4BdZxeN14kHFjNYlDXY3fdCX+gD4ICa7gmRa1e/T3Uhg0Ooh64dOUMktMvGlqhD MD7g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=YAXOrsESrx0CdS4Q6xjLBDZXEnUh9Z0PdR9s8BvDppo=; b=QqcGKrxJBqxzOnQBbUQXUW8if+ZAC6YZNn1oU5pK+LKTm+nkzsXOY6qUug5HVM7nEe +QEPDDssfX1bGruCQokwHx3Lobt7H5hA0SpTscjnnaHeEjTHoONyeRSN2PDrsgZb78RB jQhhoSf5yu7f6udYlDmMr8dCR2M9BL6R92rtKxhRljN3ACti+Q2LyBEYUDNI6206/eOV v4Z+1TkgOg77dDSb09lLVc7EMJa2HS3GdJFm8xb0sMcieyJvLmIae8PJ7m7u6v0ODzTw 0DczeoKu8fVKAuUvYi3XCfjHbFWMTRJ9etEkNP/UkTsJA6fbC2kifh40I2pNgg1+x11E nvHQ== X-Gm-Message-State: ANoB5plHoy97eaMGMJnBeewhYfx9a8fX7bVt3A+HvaWhfWUap/sOjB3D +gPuaN6B93z7I2nJpJyYHdgUsIzyDd4= X-Google-Smtp-Source: AA0mqf7bLMTQFhWrdBJoIGa4xIjQbS5vJ9zm/mLC5/L9i1Mul32aXXmMdyPekGrKbIbgzqqPfdvdgJT7y9o= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:961a:360d:6816:d7ba]) (user=glider job=sendgmr) by 2002:a05:6402:2948:b0:463:bc31:2604 with SMTP id ed8-20020a056402294800b00463bc312604mr73708091edb.32.1670252264258; Mon, 05 Dec 2022 06:57:44 -0800 (PST) Date: Mon, 5 Dec 2022 15:57:40 +0100 In-Reply-To: <20221205132558.63484-1-glider@google.com> Mime-Version: 1.0 References: <20221205132558.63484-1-glider@google.com> X-Mailer: git-send-email 2.39.0.rc0.267.gcb52ba06e7-goog Message-ID: <20221205145740.694038-1-glider@google.com> Subject: [PATCH v2] kmsan: fix memcpy tests From: Alexander Potapenko To: glider@google.com Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, elver@google.com, dvyukov@google.com, linux-mm@kvack.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Recent Clang changes may cause it to delete calls of memcpy(), if the source is an uninitialized volatile local. This happens because passing a pointer to a volatile local into memcpy() discards the volatile qualifier, giving the compiler a free hand to optimize the memcpy() call away. Use OPTIMIZER_HIDE_VAR() to hide the uninitialized var from the too-smart compiler. Suggested-by: Marco Elver Signed-off-by: Alexander Potapenko Reviewed-by: Marco Elver --- mm/kmsan/kmsan_test.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c index 9a29ea2dbfb9b..eb44ef3c5f290 100644 --- a/mm/kmsan/kmsan_test.c +++ b/mm/kmsan/kmsan_test.c @@ -419,6 +419,7 @@ static void test_memcpy_aligned_to_aligned(struct kunit= *test) kunit_info( test, "memcpy()ing aligned uninit src to aligned dst (UMR report)\n"); + OPTIMIZER_HIDE_VAR(uninit_src); memcpy((void *)&dst, (void *)&uninit_src, sizeof(uninit_src)); kmsan_check_memory((void *)&dst, sizeof(dst)); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); @@ -441,6 +442,7 @@ static void test_memcpy_aligned_to_unaligned(struct kun= it *test) kunit_info( test, "memcpy()ing aligned uninit src to unaligned dst (UMR report)\n"); + OPTIMIZER_HIDE_VAR(uninit_src); memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src)); kmsan_check_memory((void *)dst, 4); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); @@ -464,6 +466,7 @@ static void test_memcpy_aligned_to_unaligned2(struct ku= nit *test) kunit_info( test, "memcpy()ing aligned uninit src to unaligned dst - part 2 (UMR report)\n= "); + OPTIMIZER_HIDE_VAR(uninit_src); memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src)); kmsan_check_memory((void *)&dst[4], sizeof(uninit_src)); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); --=20 2.39.0.rc0.267.gcb52ba06e7-goog