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=-17.2 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,URIBL_BLOCKED, 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 B4A6EC433ED for ; Thu, 15 Apr 2021 10:00:55 +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 6BBC9611AD for ; Thu, 15 Apr 2021 10:00:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6BBC9611AD 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.111007.212155 (Exim 4.92) (envelope-from ) id 1lWynb-0004Ce-6L; Thu, 15 Apr 2021 10:00:35 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 111007.212155; Thu, 15 Apr 2021 10:00:35 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lWynb-0004CX-3E; Thu, 15 Apr 2021 10:00:35 +0000 Received: by outflank-mailman (input) for mailman id 111007; Thu, 15 Apr 2021 10:00:33 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lWynZ-0004CS-Ix for xen-devel@lists.xenproject.org; Thu, 15 Apr 2021 10:00:33 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 601d5360-3883-4a65-90f1-342a65b5c9aa; Thu, 15 Apr 2021 10:00:32 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D28EFAC6E; Thu, 15 Apr 2021 10:00:31 +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: 601d5360-3883-4a65-90f1-342a65b5c9aa 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=1618480831; 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=ioUWuPsbx/s6giZpQsdPZKdLpDXqGxqPVk3s4U++FZM=; b=lvYyWxxTca7lzABZZRnLf80qD52vq2MUYgYt1peLOlUjGi9ScKJjqxFIp3M2X35txeb7rB ftKGIwsEqxEiAf+82VFMSJiX2cvY+NDA0BmV2KDQiaqlGi5cB4cJo2MzpIcI5Om3JkZkqr hUkbmZ5cDlDYlgt5wMKqGuZyWGi0KQc= Subject: Ping (x86): [PATCH 01/23] lib: move muldiv64() From: Jan Beulich To: Andrew Cooper , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , "xen-devel@lists.xenproject.org" References: Message-ID: <48621f47-4c7b-a249-014a-9f5bc65abaaf@suse.com> Date: Thu, 15 Apr 2021 12:00:31 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 01.04.2021 12:19, Jan Beulich wrote: > Make this a separate archive member under lib/. While doing so, don't > move latently broken x86 assembly though: Fix the constraints, such > that properly extending inputs to 64-bit won't just be a side effect of > needing to copy registers, and such that we won't fail to clobber %rdx. > > Signed-off-by: Jan Beulich While this is a change to common code, there being a specific x86 aspect here I can understand that Julien would prefer to not ack this without an x86 maintainer having reviewed the change. May I ask for feedback here, as I'd prefer to commit at least the first few patches of this series before re-posting the rest. Thanks, Jan > --- a/xen/common/lib.c > +++ b/xen/common/lib.c > @@ -393,35 +393,6 @@ s64 __ldivmod_helper(s64 a, s64 b, s64 * > } > #endif /* BITS_PER_LONG == 32 */ > > -/* Compute with 96 bit intermediate result: (a*b)/c */ > -uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c) > -{ > -#ifdef CONFIG_X86 > - asm ( "mul %%rdx; div %%rcx" : "=a" (a) : "0" (a), "d" (b), "c" (c) ); > - return a; > -#else > - union { > - uint64_t ll; > - struct { > -#ifdef WORDS_BIGENDIAN > - uint32_t high, low; > -#else > - uint32_t low, high; > -#endif > - } l; > - } u, res; > - uint64_t rl, rh; > - > - u.ll = a; > - rl = (uint64_t)u.l.low * (uint64_t)b; > - rh = (uint64_t)u.l.high * (uint64_t)b; > - rh += (rl >> 32); > - res.l.high = rh / c; > - res.l.low = (((rh % c) << 32) + (rl & 0xffffffff)) / c; > - return res.ll; > -#endif > -} > - > /* > * Local variables: > * mode: C > --- a/xen/lib/Makefile > +++ b/xen/lib/Makefile > @@ -4,6 +4,7 @@ lib-y += bsearch.o > lib-y += ctors.o > lib-y += ctype.o > lib-y += list-sort.o > +lib-y += muldiv64.o > lib-y += parse-size.o > lib-y += rbtree.o > lib-y += sort.o > --- /dev/null > +++ b/xen/lib/muldiv64.c > @@ -0,0 +1,44 @@ > +#include > + > +/* Compute with 96 bit intermediate result: (a*b)/c */ > +uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c) > +{ > +#ifdef CONFIG_X86 > + asm ( "mulq %1; divq %2" : "+a" (a) > + : "rm" ((uint64_t)b), "rm" ((uint64_t)c) > + : "rdx" ); > + > + return a; > +#else > + union { > + uint64_t ll; > + struct { > +#ifdef WORDS_BIGENDIAN > + uint32_t high, low; > +#else > + uint32_t low, high; > +#endif > + } l; > + } u, res; > + uint64_t rl, rh; > + > + u.ll = a; > + rl = (uint64_t)u.l.low * (uint64_t)b; > + rh = (uint64_t)u.l.high * (uint64_t)b; > + rh += (rl >> 32); > + res.l.high = rh / c; > + res.l.low = (((rh % c) << 32) + (rl & 0xffffffff)) / c; > + > + return res.ll; > +#endif > +} > + > +/* > + * Local variables: > + * mode: C > + * c-file-style: "BSD" > + * c-basic-offset: 4 > + * tab-width: 4 > + * indent-tabs-mode: nil > + * End: > + */ > >