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[2620:137:e000::1:20]) by mx.google.com with ESMTP id kf5-20020a17090305c500b0019cf7f260afsi11127942plb.37.2023.03.01.06.54.08; Wed, 01 Mar 2023 06:54:22 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=TZbcESbs; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229577AbjCAOjt (ORCPT + 99 others); Wed, 1 Mar 2023 09:39:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230055AbjCAOjl (ORCPT ); Wed, 1 Mar 2023 09:39:41 -0500 Received: from mail-ed1-x549.google.com (mail-ed1-x549.google.com [IPv6:2a00:1450:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7688CB479 for ; Wed, 1 Mar 2023 06:39:40 -0800 (PST) Received: by mail-ed1-x549.google.com with SMTP id cf11-20020a0564020b8b00b0049ec3a108beso19362796edb.7 for ; Wed, 01 Mar 2023 06:39:40 -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=GvEmc+TQ/70wBv4c0+3F8h651+3YM9ltVwHdaJENm+0=; b=TZbcESbsWwNX7ITUi/aZMlklXQLIxXSFS8qC4CBgfWLzgdWV4sw7TnmemklpH6W7Bc A7y93ECEz75USteW8FD3Y1XqRtJk5z3dpdOjwx44G2Jjuz+Z4hitvfk4TnGhEpzcwscE ecg0YS6TcupDfdmQ4FiWgzFt1XEr6a7zKBTWdlnNhV5j7eNaBRDBF61cN2PiP+iE5mTh 91+plLrvqvm2QV627pn0K767iy62E8FL4Syt1zWC06tG2/CxQdIgC4GhP+p/aeN6q3xd 8FPlln8dfQ68QkVsu4QnH0TBtMDPHUtGDPr6mhY3CY6Efu84yLWgr+mHbxwvH+VHgIa6 MHVA== 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=GvEmc+TQ/70wBv4c0+3F8h651+3YM9ltVwHdaJENm+0=; b=lU8YQNB72+bQx63FO2imjXTNGIHfZSNxtcsI8Gu5KCiOabTvqBYpV1gzrrrLM6A3bT 1qX/TcELFo6yyKdhIiiLN45UzfyGQuB6i3EJMcKxfBkrkXVGo9GZW/5VK+eRAWLWGWvb VQuhyxWXcMF1reAk/Y0Gic7XAjc1uDwL85XRbRfzzCtze8yEXxuO7i6GRODGWMqXOFfU HNMkfrO3UJIcfYdxDHE50yKLNXLcPurslZ/Hr0FSzl0ImQ4WzU6d2G5b8oLbW0hWSKYf MQ+GA0oUWSYUGiLMDo58zFbFJVs01HbP3cW3hBkY263vVpfbfmSU4XlhdRAc84Wftc9E DYJw== X-Gm-Message-State: AO0yUKUb4EXzN4W1FE37Ae2GAv5+0UZkdt43cygsFgVLd3g37i/F7xg9 gzdQHxFFspqiPtUNYbKVqb/UniwYm3Y= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:3c31:b0cf:1498:e916]) (user=glider job=sendgmr) by 2002:a50:d6db:0:b0:4aa:a4df:23fc with SMTP id l27-20020a50d6db000000b004aaa4df23fcmr4014799edj.1.1677681579977; Wed, 01 Mar 2023 06:39:39 -0800 (PST) Date: Wed, 1 Mar 2023 15:39:31 +0100 In-Reply-To: <20230301143933.2374658-1-glider@google.com> Mime-Version: 1.0 References: <20230301143933.2374658-1-glider@google.com> X-Mailer: git-send-email 2.39.2.722.g9855ee24e9-goog Message-ID: <20230301143933.2374658-2-glider@google.com> Subject: [PATCH 2/4] kmsan: another take at fixing memcpy tests From: Alexander Potapenko To: glider@google.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, dave.hansen@linux.intel.com, hpa@zytor.com, akpm@linux-foundation.org, elver@google.com, dvyukov@google.com, nathan@kernel.org, ndesaulniers@google.com, kasan-dev@googlegroups.com X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1759177565184302032?= X-GMAIL-MSGID: =?utf-8?q?1759177565184302032?= 5478afc55a21 ("kmsan: fix memcpy tests") uses OPTIMIZER_HIDE_VAR() to hide the uninitialized var from the compiler optimizations. However OPTIMIZER_HIDE_VAR(uninit) enforces an immediate check of @uninit, so memcpy tests did not actually check the behavior of memcpy(), because they always contained a KMSAN report. Replace OPTIMIZER_HIDE_VAR() with a file-local asm macro that just clobbers the memory, and add a test case for memcpy() that does not expect an error report. Also reflow kmsan_test.c with clang-format. Signed-off-by: Alexander Potapenko --- mm/kmsan/kmsan_test.c | 43 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 37 insertions(+), 6 deletions(-) diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c index 088e21a48dc4b..cc98a3f4e0899 100644 --- a/mm/kmsan/kmsan_test.c +++ b/mm/kmsan/kmsan_test.c @@ -407,6 +407,36 @@ 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. + */ +#define DO_NOT_OPTIMIZE(var) asm("" ::: "memory") + +/* + * 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; + + // Ensure DO_NOT_OPTIMIZE() does not cause extra checks. + 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)); + kmsan_check_memory((void *)&dst, sizeof(dst)); + KUNIT_EXPECT_TRUE(test, report_matches(&expect)); +} + /* * Test case: ensure that memcpy() correctly copies uninitialized values between * aligned `src` and `dst`. @@ -420,7 +450,7 @@ 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); + DO_NOT_OPTIMIZE(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)); @@ -443,7 +473,7 @@ static void test_memcpy_aligned_to_unaligned(struct kunit *test) kunit_info( test, "memcpy()ing aligned uninit src to unaligned dst (UMR report)\n"); - OPTIMIZER_HIDE_VAR(uninit_src); + DO_NOT_OPTIMIZE(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)); @@ -467,13 +497,14 @@ 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"); - OPTIMIZER_HIDE_VAR(uninit_src); + DO_NOT_OPTIMIZE(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)); } -static noinline void fibonacci(int *array, int size, int start) { +static noinline void fibonacci(int *array, int size, int start) +{ if (start < 2 || (start == size)) return; array[start] = array[start - 1] + array[start - 2]; @@ -482,8 +513,7 @@ static noinline void fibonacci(int *array, int size, int start) { static void test_long_origin_chain(struct kunit *test) { - EXPECTATION_UNINIT_VALUE_FN(expect, - "test_long_origin_chain"); + EXPECTATION_UNINIT_VALUE_FN(expect, "test_long_origin_chain"); /* (KMSAN_MAX_ORIGIN_DEPTH * 2) recursive calls to fibonacci(). */ volatile int accum[KMSAN_MAX_ORIGIN_DEPTH * 2 + 2]; int last = ARRAY_SIZE(accum) - 1; @@ -515,6 +545,7 @@ static struct kunit_case kmsan_test_cases[] = { KUNIT_CASE(test_uaf), KUNIT_CASE(test_percpu_propagate), KUNIT_CASE(test_printk), + KUNIT_CASE(test_init_memcpy), KUNIT_CASE(test_memcpy_aligned_to_aligned), KUNIT_CASE(test_memcpy_aligned_to_unaligned), KUNIT_CASE(test_memcpy_aligned_to_unaligned2),