From patchwork Tue Jan 31 21:36:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Noah Goldstein X-Patchwork-Id: 64046 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 1AA623858422 for ; Tue, 31 Jan 2023 21:37:27 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1AA623858422 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1675201047; bh=8+wlE59KZa+v/QWSETGdUvrb6zUmrYxoPsk7LXRyAoE=; h=To:Cc:Subject:Date:List-Id:List-Unsubscribe:List-Archive: List-Post:List-Help:List-Subscribe:From:Reply-To:From; b=jkPJgrftwUbyDtUvsx3nEAocLnDKCSVRKGmlFBk78R8dsPmFxZl9TsWm/eqFIZ4RR Rsw3/FvhkoH1L65wyNcj6qyiAGq3zBIfmlsAqlCC0qHrMklCLSIyMzZ5vC9uhe04yX Fqbrgj7T0L7k8NlXB+vkubSKB4mIMM73XfUugl30= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-ej1-x630.google.com (mail-ej1-x630.google.com [IPv6:2a00:1450:4864:20::630]) by sourceware.org (Postfix) with ESMTPS id 9DCF03858D33 for ; Tue, 31 Jan 2023 21:37:01 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 9DCF03858D33 Received: by mail-ej1-x630.google.com with SMTP id qw12so29778602ejc.2 for ; Tue, 31 Jan 2023 13:37:01 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=8+wlE59KZa+v/QWSETGdUvrb6zUmrYxoPsk7LXRyAoE=; b=iqCwR7F40NqT1+2km1c9y0lLLrojqS2CU9wKUlYnvsvi211paZTIf10GcXL8jJ+MP2 BIIrRi96KCm9eWNUtiWhMS/FBLp0+5idAKTdei3FHgdBvqL3xIq++vBNTXjIUoEe9lOx PRtknaUGPWo2MN9XDu127JDTG26W0qvkcCM73cG4WTzst1VpTAxyyAXCsRpjvrnFch0E Gw4wiHdoGMXAq1KVbMydHTtsIxRDpILhQGX9pOYvfJH7PdC1OWRcno1yfxrJujDD4eua fKp4bN9fx2z53ELO40N+MUq/ZFz+pPsDb1zZkvwRvfE3YPlVKQXAvsdhgNrf83yk33pr Q/iQ== X-Gm-Message-State: AO0yUKVAy5FPnfoXLqejs74SYBDXVrhJaOie9QehuNXHKKCmC5ecYKtI yvaP8X4OvxCGfUMSp0c43r2u/UJlqcM= X-Google-Smtp-Source: AK7set/Ws/VWFKgFai01OpjrG11AMI5U/NkZZvV4zSgnwK05ODPG60t7NIKrJ4AqRzvjg4GsKnE18g== X-Received: by 2002:a17:907:7ea2:b0:88d:72c0:611 with SMTP id qb34-20020a1709077ea200b0088d72c00611mr979229ejc.3.1675201019825; Tue, 31 Jan 2023 13:36:59 -0800 (PST) Received: from noahgold-desk.lan (2603-8080-1301-76c6-2080-7b0a-0a99-f439.res6.spectrum.com. [2603:8080:1301:76c6:2080:7b0a:a99:f439]) by smtp.gmail.com with ESMTPSA id bj14-20020a170906b04e00b00878a8937009sm8209846ejb.199.2023.01.31.13.36.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Jan 2023 13:36:59 -0800 (PST) To: libc-alpha@sourceware.org Cc: goldstein.w.n@gmail.com, hjl.tools@gmail.com, carlos@systemhalted.org Subject: [PATCH v1] x86: Fix strncat-avx2.S when `src` has no null-term [BZ #30065] Date: Tue, 31 Jan 2023 15:36:55 -0600 Message-Id: <20230131213655.4033602-1-goldstein.w.n@gmail.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Spam-Status: No, score=-12.1 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Noah Goldstein via Libc-alpha From: Noah Goldstein Reply-To: Noah Goldstein Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Two issue: 1) Zero-length check is doing: ``` test %rdx, %rdx jl L(zero_len) ``` which doesn't actually check zero (was at some point `decq` and the flag never got updated). The fix is just make the flag `jle` i.e: ``` test %rdx, %rdx jle L(zero_len) ``` 2) Length check in page-cross case checking if we should continue is doing: ``` cmpq %r8, %rdx jb L(page_cross_small) ``` which means we will continue searching for null-term if length ends at the end of a page and there was no null-term in `src`. The fix is to make the flag: ``` cmpq %r8, %rdx jbe L(page_cross_small) ``` --- string/test-strncat.c | 25 ++++++++++++++++++++++++- sysdeps/x86_64/multiarch/strncat-avx2.S | 4 ++-- 2 files changed, 26 insertions(+), 3 deletions(-) diff --git a/string/test-strncat.c b/string/test-strncat.c index e03d329e1c..c0cde206ee 100644 --- a/string/test-strncat.c +++ b/string/test-strncat.c @@ -28,6 +28,7 @@ # define CHAR char # define UCHAR unsigned char # define SIMPLE_STRNCAT simple_strncat +# define STRNLEN strnlen # define STRLEN strlen # define MEMSET memset # define MEMCPY memcpy @@ -40,6 +41,7 @@ # define CHAR wchar_t # define UCHAR wchar_t # define SIMPLE_STRNCAT simple_wcsncat +# define STRNLEN wcsnlen # define STRLEN wcslen # define MEMSET wmemset # define MEMCPY wmemcpy @@ -78,7 +80,7 @@ do_one_test (impl_t *impl, CHAR *dst, const CHAR *src, size_t n) return; } - size_t len = STRLEN (src); + size_t len = STRNLEN (src, n); if (MEMCMP (dst + k, src, len + 1 > n ? n : len + 1) != 0) { error (0, 0, "Incorrect concatenation in function %s", @@ -95,6 +97,26 @@ do_one_test (impl_t *impl, CHAR *dst, const CHAR *src, size_t n) } } +static void +do_test_src_no_nullterm_bz30065 (void) +{ + /* NB: "src does not need to be null-terminated if it contains n or more + * bytes." */ + CHAR *s1, *s2; + size_t bound = page_size / sizeof (CHAR); + s1 = (CHAR *) (buf1 + BUF1PAGES * page_size); + s2 = (CHAR *) buf2; + MEMSET (s1 - bound, -1, bound); + for (size_t n = 0; n < bound; ++n) + { + FOR_EACH_IMPL (impl, 0) + { + s2[0] = '\0'; + do_one_test (impl, s2, s1 - n, n); + } + } +} + static void do_test (size_t align1, size_t align2, size_t len1, size_t len2, size_t n, int max_char) @@ -372,6 +394,7 @@ test_main (void) do_random_tests (); do_overflow_tests (); + do_test_src_no_nullterm_bz30065 (); return ret; } diff --git a/sysdeps/x86_64/multiarch/strncat-avx2.S b/sysdeps/x86_64/multiarch/strncat-avx2.S index b380e8e11c..c2ff202238 100644 --- a/sysdeps/x86_64/multiarch/strncat-avx2.S +++ b/sysdeps/x86_64/multiarch/strncat-avx2.S @@ -66,7 +66,7 @@ ENTRY(STRNCAT) salq $2, %rdx # else test %rdx, %rdx - jl L(zero_len) + jle L(zero_len) # endif vpxor %VZERO_128, %VZERO_128, %VZERO_128 @@ -387,7 +387,7 @@ L(page_cross): subl %esi, %r8d andl $(VEC_SIZE - 1), %r8d cmpq %r8, %rdx - jb L(page_cross_small) + jbe L(page_cross_small) /* Optimizing more aggressively for space as this is very cold code. This saves 2x cache lines. */