From patchwork Thu Apr 1 10:19:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 12177691 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 381FBC433B4 for ; Thu, 1 Apr 2021 10:19:34 +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 C5C4961056 for ; Thu, 1 Apr 2021 10:19:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C5C4961056 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.104280.199268 (Exim 4.92) (envelope-from ) id 1lRuQ5-0000cb-12; Thu, 01 Apr 2021 10:19:21 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 104280.199268; Thu, 01 Apr 2021 10:19:20 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lRuQ4-0000cU-U2; Thu, 01 Apr 2021 10:19:20 +0000 Received: by outflank-mailman (input) for mailman id 104280; Thu, 01 Apr 2021 10:19:19 +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 1lRuQ3-0000cP-CY for xen-devel@lists.xenproject.org; Thu, 01 Apr 2021 10:19:19 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 18698b2d-322e-4a69-a3c1-ecbb84983cfa; Thu, 01 Apr 2021 10:19:18 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A60E8AED7; Thu, 1 Apr 2021 10:19:17 +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: 18698b2d-322e-4a69-a3c1-ecbb84983cfa 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=1617272357; 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=9n+mI1T3eTMXqMQfpWtBTAwMJf+lLEmiOgcGI7/pMvs=; b=VFOQcT58NhjmucUyXOze1BHcqSKPdeJjv3E34UTJrUjtwxeQfDuqavnRIX+nBI4z/KGdQe hriJ50IRFM26dH19iKmqiAfkJQvnV8lW02MQB4ItZMfR/wAXt4eQ2mCRw8gsKACHjnSiQO bSmgHjUlLNKDEbVFv/j+z0liIoNsclg= Subject: [PATCH 01/23] lib: move muldiv64() From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu References: Message-ID: Date: Thu, 1 Apr 2021 12:19:16 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US 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 Acked-by: Roger Pau Monné --- 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: + */