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=-12.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,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 F00DFC433DB for ; Tue, 23 Mar 2021 13:02:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BADC9619B7 for ; Tue, 23 Mar 2021 13:02:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229884AbhCWNCI (ORCPT ); Tue, 23 Mar 2021 09:02:08 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:35065 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231260AbhCWNB4 (ORCPT ); Tue, 23 Mar 2021 09:01:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616504515; h=from:from:reply-to:subject:subject: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=xRWcOx4dEk1OZdkM5dZDcgA03Zh7tzRnPPLTLDtGprk=; b=I8BmNZ+msjw8mLvN9vK9wabTSyRpgK6QJdV5aWHCTLNJnsNGpEu1QQ/kGGCpd8JWEpqTeE XzbeAS27I3AdwdkWXFTEeu+n2weBZfur7uH4svIii9OVc1RDB3PCl4k0M9ctNyr5FvFLaH RKHy/46Sj/LqdeUQqAP/5kUgcmh6GK4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-126-madxJTR2MJS4OI7C_7vhhA-1; Tue, 23 Mar 2021 09:01:51 -0400 X-MC-Unique: madxJTR2MJS4OI7C_7vhhA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A488A18C8C06; Tue, 23 Mar 2021 13:01:50 +0000 (UTC) Received: from thuth.remote.csb (ovpn-112-54.ams2.redhat.com [10.36.112.54]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2007E5C1CF; Tue, 23 Mar 2021 13:01:48 +0000 (UTC) Subject: Re: [kvm-unit-tests PATCH v2 1/4] lib/string: Add strnlen, strrchr and strtoul To: Andrew Jones , Nikos Nikoleris Cc: kvm@vger.kernel.org, pbonzini@redhat.com, alexandru.elisei@arm.com, andre.przywara@arm.com References: <20210318180727.116004-1-nikos.nikoleris@arm.com> <20210318180727.116004-2-nikos.nikoleris@arm.com> <20210322083523.r7bu7ledgasqjduy@kamzik.brq.redhat.com> <20210323121415.rss3evguqb3b7vvz@kamzik.brq.redhat.com> From: Thomas Huth Message-ID: Date: Tue, 23 Mar 2021 14:01:47 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210323121415.rss3evguqb3b7vvz@kamzik.brq.redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 23/03/2021 13.14, Andrew Jones wrote: > On Mon, Mar 22, 2021 at 09:35:23AM +0100, Andrew Jones wrote: >> @@ -208,23 +209,46 @@ unsigned long int strtoul(const char *nptr, char **endptr, int base) >> c = *s - 'A' + 10; >> else >> break; >> - acc = acc * base + c; >> + >> + if (is_signed) { >> + long __acc = (long)acc; >> + overflow = __builtin_smull_overflow(__acc, base, &__acc); >> + assert(!overflow); >> + overflow = __builtin_saddl_overflow(__acc, c, &__acc); >> + assert(!overflow); >> + acc = (unsigned long)__acc; >> + } else { >> + overflow = __builtin_umull_overflow(acc, base, &acc); >> + assert(!overflow); >> + overflow = __builtin_uaddl_overflow(acc, c, &acc); >> + assert(!overflow); >> + } >> + > > Unfortunately my use of these builtins isn't loved by older compilers, > like the one used by the build-centos7 pipeline in our gitlab CI. I > could wrap them in an #if GCC_VERSION >= 50100 and just have the old > 'acc = acc * base + c' as the fallback, but that's not pretty and > would also mean that clang would use the fallback too. Maybe we can > try and make our compiler.h more fancy in order to provide a > COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW define like linux does for > both gcc and clang. Or, we could just forgot the overflow checking. > > Anybody else have suggestions? Paolo? Thomas? What does a "normal" libc implementation do (e.g. glibc)? If it is also not doing overflow checking, I think we also don't need it in the kvm-unit-tests. Thomas