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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A924DC56202 for ; Fri, 13 Nov 2020 12:03:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 624D722240 for ; Fri, 13 Nov 2020 12:03:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726903AbgKMMDl (ORCPT ); Fri, 13 Nov 2020 07:03:41 -0500 Received: from foss.arm.com ([217.140.110.172]:36778 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726822AbgKMLoe (ORCPT ); Fri, 13 Nov 2020 06:44:34 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C0C6914BF; Fri, 13 Nov 2020 03:44:33 -0800 (PST) Received: from [10.37.12.45] (unknown [10.37.12.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D532F3F6CF; Fri, 13 Nov 2020 03:44:30 -0800 (PST) Subject: Re: [PATCH v9 44/44] kselftest/arm64: Check GCR_EL1 after context switch To: Alexander Potapenko , Andrey Konovalov Cc: Catalin Marinas , Will Deacon , Dmitry Vyukov , Andrey Ryabinin , Marco Elver , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , Andrew Morton , kasan-dev , Linux ARM , Linux Memory Management List , LKML References: From: Vincenzo Frascino Message-ID: Date: Fri, 13 Nov 2020 11:47:35 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Alexander, thank you for the review. On 11/12/20 3:59 PM, Alexander Potapenko wrote: > On Tue, Nov 10, 2020 at 11:12 PM Andrey Konovalov wrote: >> >> From: Vincenzo Frascino >> >> This test is specific to MTE and verifies that the GCR_EL1 register >> is context switched correctly. >> >> It spawn 1024 processes and each process spawns 5 threads. Each thread > > Nit: "spawns" > I will fix it in the next iteration. > >> + srand(time(NULL) ^ (pid << 16) ^ (tid << 16)); >> + >> + prctl_tag_mask = rand() % 0xffff; > > Nit: if you want values between 0 and 0xffff you probably want to use > bitwise AND. > The main goal here is to have a good probability of having a different setting to the GCR_EL1 register. Hence the difference in between 0xffff and 0xffff-1 is negligible. Anyway I agree that we should aim to cover all the possible combinations. > >> + >> +int execute_test(pid_t pid) >> +{ >> + pthread_t thread_id[MAX_THREADS]; >> + int thread_data[MAX_THREADS]; >> + >> + for (int i = 0; i < MAX_THREADS; i++) >> + pthread_create(&thread_id[i], NULL, >> + execute_thread, (void *)&pid); > > It might be simpler to call getpid() in execute_thread() instead. > Yes it might, but I would like to avoid another syscall if I can. >> +int mte_gcr_fork_test() >> +{ >> + pid_t pid[NUM_ITERATIONS]; >> + int results[NUM_ITERATIONS]; >> + pid_t cpid; >> + int res; >> + >> + for (int i = 0; i < NUM_ITERATIONS; i++) { >> + pid[i] = fork(); >> + >> + if (pid[i] == 0) { > > pid[i] isn't used anywhere else. Did you want to keep the pids to > ensure that all children finished the work? > If not, we can probably go with a scalar here. > Yes, I agree, I had some debug code making use of it, but I removed it in the end. > >> + for (int i = 0; i < NUM_ITERATIONS; i++) { >> + wait(&res); >> + >> + if(WIFEXITED(res)) >> + results[i] = WEXITSTATUS(res); >> + else >> + --i; > > Won't we get stuck in this loop if fork() returns -1 for one of the processes? > Yes I agree, I forgot to check a condition. We should abort the test in such a case returning KSFT_FAIL directly. >> + } >> + >> + for (int i = 0; i < NUM_ITERATIONS; i++) >> + if (results[i] == KSFT_FAIL) >> + return KSFT_FAIL; >> + >> + return KSFT_PASS; >> +} >> + > > -- Regards, Vincenzo