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[2620:137:e000::1:20]) by mx.google.com with ESMTP id g3-20020a170902740300b001926b288ae9si2368468pll.82.2023.03.03.06.15.52; Fri, 03 Mar 2023 06:16:06 -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=ZfSfmqBM; 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 S231177AbjCCOO5 (ORCPT + 99 others); Fri, 3 Mar 2023 09:14:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231207AbjCCOOq (ORCPT ); Fri, 3 Mar 2023 09:14:46 -0500 Received: from mail-ed1-x54a.google.com (mail-ed1-x54a.google.com [IPv6:2a00:1450:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 694AD17152 for ; Fri, 3 Mar 2023 06:14:45 -0800 (PST) Received: by mail-ed1-x54a.google.com with SMTP id cf11-20020a0564020b8b00b0049ec3a108beso4159524edb.7 for ; Fri, 03 Mar 2023 06:14:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1677852884; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=NzrUAKqOf4lIqj2sXdyqoZ2Q8eXyDe5JYgJyXOtPsCY=; b=ZfSfmqBMuJ+vwMDxG5i4+5C+tNEglr4loWmKR6Z0RkZfjr+jAbJCKs+E8HdnY+/484 U4Tnah/k4Gjd5sm2yqp/0nKmTL54cbtEXdkKAgXSe42PIyTbE0SRGadQQmam3JIAUfvC a5ouWadlWnMykwg3du4wr7YFd0UA4Nmn97zesSEosU4X3DChC2nSvSKQyOpTfHECBKv7 gZXhfuN9a1gIdRxhqPU3dNXM0LfelTB/RT1xvfB+vRM3dNsvbeS0WfFdt8jqYekhXOzi 337mBrnvoEXkOMuKAADUY1doomtGT8K8uQlYbbOdXMj9ai3/IQ/6zMJlcrmOBZHFmz/Z uWtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1677852884; 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=NzrUAKqOf4lIqj2sXdyqoZ2Q8eXyDe5JYgJyXOtPsCY=; b=BRe31E6W1tfSDDjtXdl1S6Bf/Un5oUtiqT/gSYCwC8Ldxv6lJ17MvfMwdmK6/sxoY8 h8GHCanmiG4FJJNKK/k3WnT9rVruYDZJY80U2eE/l4W4EYiIx0E1vYQCtvm5ae6fYGMD AD8msGNgQOLFU/J1S4C7AEG0xWhA0yHcf3hIvZik5tXHKpWjM172lGF9Mucy5Efikgly U6QZR4rTxS2U7UpWz8XJTZQktDbGfvkJNWRCNPBTr0x5NONgxy1mND9gGkg5TrHpwPwR HIQh5OkHdRcr7/y3hYdKKdCikQnF8f83d4rX5iUsT590uIEXEQKAmDwXX6arcYV2tF/b 6ghA== X-Gm-Message-State: AO0yUKUy6ih5OraAX6o8+ohAfnroRzVrOfyYPUN9wWAbvU9YHACWlRrk fOItoNuWjNx64SFBlqtKys9YbWXd/08= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:f11e:2fac:5069:a04d]) (user=glider job=sendgmr) by 2002:a17:906:d041:b0:8bf:e82a:2988 with SMTP id bo1-20020a170906d04100b008bfe82a2988mr938462ejb.4.1677852883928; Fri, 03 Mar 2023 06:14:43 -0800 (PST) Date: Fri, 3 Mar 2023 15:14:31 +0100 In-Reply-To: <20230303141433.3422671-1-glider@google.com> Mime-Version: 1.0 References: <20230303141433.3422671-1-glider@google.com> X-Mailer: git-send-email 2.40.0.rc0.216.gc4246ad0f0-goog Message-ID: <20230303141433.3422671-2-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?1759356351583777452?= X-GMAIL-MSGID: =?utf-8?q?1759356351583777452?= commit 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 macro that just clobbers the memory with a barrier(), 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 Reviewed-by: Marco Elver --- v2: - replace inline assembly with a barrier(), update comments --- mm/kmsan/kmsan_test.c | 44 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 38 insertions(+), 6 deletions(-) diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c index 088e21a48dc4b..aeddfdd4f679f 100644 --- a/mm/kmsan/kmsan_test.c +++ b/mm/kmsan/kmsan_test.c @@ -407,6 +407,37 @@ 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() + +/* + * 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. + */ +static void test_init_memcpy(struct kunit *test) +{ + EXPECTATION_NO_REPORT(expect); + volatile int src; + volatile int 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)); + 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 +451,7 @@ 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 +474,7 @@ 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 +498,14 @@ 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 +514,7 @@ 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 +546,7 @@ 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),