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 E7DEBCA0EC3 for ; Mon, 11 Sep 2023 22:46:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238077AbjIKWiq (ORCPT ); Mon, 11 Sep 2023 18:38:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47914 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240923AbjIKO5V (ORCPT ); Mon, 11 Sep 2023 10:57:21 -0400 Received: from mail-wr1-x449.google.com (mail-wr1-x449.google.com [IPv6:2a00:1450:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1B09E4B for ; Mon, 11 Sep 2023 07:57:16 -0700 (PDT) Received: by mail-wr1-x449.google.com with SMTP id ffacd0b85a97d-313c930ee0eso2827347f8f.0 for ; Mon, 11 Sep 2023 07:57:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1694444235; x=1695049035; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=TCSVjF+G/Yb3+dPBWGz9EuIiyh+/ldUAKZlZ+MbeoHM=; b=alo7MMQz1MoiVX26Nna85O1ht7DzrLo13Y80EZEvIRzoNKOm/oR6/TGBaWp9WcwE1J gDccdf7Nl6NILf799HOavx4Tbfp7GAQUiMpGXRIJxx0obnPgHrss0/qaSzyxuyTM5I5N YGXSYIBWnuR3LByR7hEDPUT3UyEwRpgd9KJZ8GonoddcHvQQJVcr8H+YNO5NYOOAS25P gsfa605kNP96KeaaYJL3pUDvIZ4LsBuFc9bnEKmvPioNDO2e1DnvAXwGKpzKPt0jHzgb /2pUXkLK+JrzMW8tl1ip+1yaxOAfGXEGHVO4vggCvi9zSm4ivS1BaVjKBGVllcWhCXnF SYlQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694444235; x=1695049035; 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=TCSVjF+G/Yb3+dPBWGz9EuIiyh+/ldUAKZlZ+MbeoHM=; b=DpF67JdNpUbX/q1aj0i5MXqMSD1CmLJ22xeg2rmPf0KS/QkniNCD15gOsLDhkegkCD avwww6Jm5Y93luoJkb5+PRgPIS91VkB2zqVSBlAV9pIbZSYRjpE92GBGvNNVMRxSQTYq MUu8YSusiA/1XVC0wpDArbLTHknQpPf+UMkybazfl9nc+GNgKvCfgbAbbJzKFsOdTpVG j/wS5HzyAhNpBFAeAgwHuwtA5kaXUCnQVTebE6jlMJ0ZdTOIlRnsCTVOymSeIziFsUqV og0PXoSnmJ/ouxZ3IFXBgioCCe4eQuXn/R0YvZOlHw+htI6VknLArByfPTO5HJ3Mz1x+ RE/A== X-Gm-Message-State: AOJu0YzYH9hjFwC/JoyboSm5VMUA6oTkph945QokIDzooWPLCvCRSI7J qmmGDGT04aYCzuZRb5lQ1eIoDM6D9eY= X-Google-Smtp-Source: AGHT+IF8AQnXMqKw+wXUY955bd2z842BBltBx/W8SpN0YrTJ17nBacddlqEtoES1ZoK3oQ/7F/gHOXNEgb8= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:62e7:6658:cb4:b858]) (user=glider job=sendgmr) by 2002:adf:ce84:0:b0:317:41be:d871 with SMTP id r4-20020adfce84000000b0031741bed871mr114853wrn.14.1694444235317; Mon, 11 Sep 2023 07:57:15 -0700 (PDT) Date: Mon, 11 Sep 2023 16:57:00 +0200 In-Reply-To: <20230911145702.2663753-1-glider@google.com> Mime-Version: 1.0 References: <20230911145702.2663753-1-glider@google.com> X-Mailer: git-send-email 2.42.0.283.g2d96d420d3-goog Message-ID: <20230911145702.2663753-2-glider@google.com> Subject: [PATCH v2 2/4] kmsan: prevent optimizations in memcpy tests From: Alexander Potapenko To: glider@google.com, dvyukov@google.com, elver@google.com, akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Clang 18 learned to optimize away memcpy() calls of small uninitialized scalar values. To ensure that memcpy tests in kmsan_test.c still perform calls to memcpy() (which KMSAN replaces with __msan_memcpy()), declare a separate memcpy_noinline() function with volatile parameters, which won't be optimized. Also retire DO_NOT_OPTIMIZE(), as memcpy_noinline() is apparently enough. Signed-off-by: Alexander Potapenko --- v2: - fix W=1 warnings reported by LKP test robot --- mm/kmsan/kmsan_test.c | 41 ++++++++++++++++------------------------- 1 file changed, 16 insertions(+), 25 deletions(-) diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c index 312989aa2865c..a8d4ca4a1066d 100644 --- a/mm/kmsan/kmsan_test.c +++ b/mm/kmsan/kmsan_test.c @@ -407,33 +407,25 @@ static void test_printk(struct kunit *test) KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } -/* - * Prevent the compiler from optimizing @var away. Without this, Clang may - * notice that @var is uninitialized and drop memcpy() calls that use it. - * - * There is OPTIMIZER_HIDE_VAR() in linux/compier.h that we cannot use here, - * because it is implemented as inline assembly receiving @var as a parameter - * and will enforce a KMSAN check. Same is true for e.g. barrier_data(var). - */ -#define DO_NOT_OPTIMIZE(var) barrier() +/* Prevent the compiler from inlining a memcpy() call. */ +static noinline void *memcpy_noinline(volatile void *dst, + const volatile void *src, size_t size) +{ + return memcpy((void *)dst, (const void *)src, size); +} -/* - * Test case: ensure that memcpy() correctly copies initialized values. - * Also serves as a regression test to ensure DO_NOT_OPTIMIZE() does not cause - * extra checks. - */ +/* Test case: ensure that memcpy() correctly copies initialized values. */ static void test_init_memcpy(struct kunit *test) { EXPECTATION_NO_REPORT(expect); - volatile int src; - volatile int dst = 0; + volatile long long src; + volatile long long dst = 0; - DO_NOT_OPTIMIZE(src); src = 1; kunit_info( test, "memcpy()ing aligned initialized src to aligned dst (no reports)\n"); - memcpy((void *)&dst, (void *)&src, sizeof(src)); + memcpy_noinline((void *)&dst, (void *)&src, sizeof(src)); kmsan_check_memory((void *)&dst, sizeof(dst)); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } @@ -451,8 +443,7 @@ static void test_memcpy_aligned_to_aligned(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to aligned dst (UMR report)\n"); - DO_NOT_OPTIMIZE(uninit_src); - memcpy((void *)&dst, (void *)&uninit_src, sizeof(uninit_src)); + memcpy_noinline((void *)&dst, (void *)&uninit_src, sizeof(uninit_src)); kmsan_check_memory((void *)&dst, sizeof(dst)); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } @@ -474,8 +465,9 @@ static void test_memcpy_aligned_to_unaligned(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to unaligned dst (UMR report)\n"); - DO_NOT_OPTIMIZE(uninit_src); - memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src)); + kmsan_check_memory((void *)&uninit_src, sizeof(uninit_src)); + memcpy_noinline((void *)&dst[1], (void *)&uninit_src, + sizeof(uninit_src)); kmsan_check_memory((void *)dst, 4); KUNIT_EXPECT_TRUE(test, report_matches(&expect)); } @@ -498,8 +490,8 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to unaligned dst - part 2 (UMR report)\n"); - DO_NOT_OPTIMIZE(uninit_src); - memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src)); + memcpy_noinline((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)); } @@ -513,7 +505,6 @@ static void test_memcpy_aligned_to_unaligned2(struct kunit *test) \ kunit_info(test, \ "memset" #size "() should initialize memory\n"); \ - DO_NOT_OPTIMIZE(uninit); \ memset##size((uint##size##_t *)&uninit, 0, 1); \ kmsan_check_memory((void *)&uninit, sizeof(uninit)); \ KUNIT_EXPECT_TRUE(test, report_matches(&expect)); \ -- 2.42.0.283.g2d96d420d3-goog