From patchwork Mon Mar 1 08:30:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 12108987 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=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 8601AC433E0 for ; Mon, 1 Mar 2021 08:30:38 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 41C2760202 for ; Mon, 1 Mar 2021 08:30:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41C2760202 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.91350.172641 (Exim 4.92) (envelope-from ) id 1lGdwk-0001tI-09; Mon, 01 Mar 2021 08:30:30 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 91350.172641; Mon, 01 Mar 2021 08:30:29 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lGdwj-0001tB-SO; Mon, 01 Mar 2021 08:30:29 +0000 Received: by outflank-mailman (input) for mailman id 91350; Mon, 01 Mar 2021 08:30:28 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lGdwi-0001sh-A4 for xen-devel@lists.xenproject.org; Mon, 01 Mar 2021 08:30:28 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 499a38d8-94f2-4bbf-a116-88bf048ef6bd; Mon, 01 Mar 2021 08:30:27 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 77340AF57; Mon, 1 Mar 2021 08:30:26 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 499a38d8-94f2-4bbf-a116-88bf048ef6bd X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1614587426; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=aOzC6w3LpS+/WUDq1gZ9j35Z2qxwwgvDhiN0ayxn28k=; b=QJsun6zmDjAD6AuASuQFahgLLq3KCoYBoZ8e2jwIOA/NqXegi5TueXE7C+xBeGSGsAmWyu whnr34SVQCRysf/aiTJgOa5Yyyf1xGoynn5/CaxjaDqqGUNf9ku2TZtHfrBuGsKqP14pXS sUrD3fe2bouaw32uWjHPioZQVNhrTi0= Subject: [PATCH 1/2][4.15?] sched: fix build when NR_CPUS == 1 From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Connor Davis , George Dunlap , Dario Faggioli , Ian Jackson References: Message-ID: <171d1da4-e87a-b154-5c63-a5627d4f93bc@suse.com> Date: Mon, 1 Mar 2021 09:30:26 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US In this case the compiler is recognizing that no valid array indexes remain, and hence e.g. reports: core.c: In function 'cpu_schedule_up': core.c:2769:19: error: array subscript 1 is above array bounds of 'struct vcpu *[1]' [-Werror=array-bounds] 2769 | if ( idle_vcpu[cpu] == NULL ) | ~~~~~~~~~^~~~~ Reported-by: Connor Davis Signed-off-by: Jan Beulich Reviewed-by: Dario Faggioli --- a/xen/common/sched/core.c +++ b/xen/common/sched/core.c @@ -2768,6 +2768,12 @@ static int cpu_schedule_up(unsigned int if ( cpu == 0 ) return 0; + /* + * Guard in particular against the compiler suspecting out-of-bounds + * array accesses below when NR_CPUS=1. + */ + BUG_ON(cpu >= NR_CPUS); + if ( idle_vcpu[cpu] == NULL ) vcpu_create(idle_vcpu[0]->domain, cpu); else