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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id A13E3C48BC1 for ; Wed, 14 Feb 2024 15:02:51 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.680914.1059229 (Exim 4.92) (envelope-from ) id 1raGmN-0006tT-Tf; Wed, 14 Feb 2024 15:02:31 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 680914.1059229; Wed, 14 Feb 2024 15:02:31 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1raGmN-0006tM-R3; Wed, 14 Feb 2024 15:02:31 +0000 Received: by outflank-mailman (input) for mailman id 680914; Wed, 14 Feb 2024 15:02:31 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1raGmN-0006sm-9e for xen-devel@lists.xenproject.org; Wed, 14 Feb 2024 15:02:31 +0000 Received: from mail-lf1-x133.google.com (mail-lf1-x133.google.com [2a00:1450:4864:20::133]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 12327a8e-cb4a-11ee-8a4d-1f161083a0e0; Wed, 14 Feb 2024 16:02:28 +0100 (CET) Received: by mail-lf1-x133.google.com with SMTP id 2adb3069b0e04-5114b2b3b73so6577262e87.0 for ; Wed, 14 Feb 2024 07:02:28 -0800 (PST) Received: from localhost ([213.195.118.74]) by smtp.gmail.com with ESMTPSA id oj11-20020a056214440b00b0068c71b78980sm2325105qvb.118.2024.02.14.07.02.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Feb 2024 07:02:27 -0800 (PST) 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: 12327a8e-cb4a-11ee-8a4d-1f161083a0e0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1707922948; x=1708527748; darn=lists.xenproject.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=BuGYPWEJOUTaH5rf6DAQz91oXgKrMbqT0YkEhfKJGuc=; b=SXTo5CRM5BgfBuEXKcn/qWZ1gvRq5XOqnjXuURulUCwXwMfivdcoIRvz0IUtoJutYX 04UMnh9pjIHFsjWDhaXdrs4Hi0lj9KMHd78fIhOQuabi8s+fQ86XF+C4NSI2Xng7wfkp aJeK2ei0MKdK4thpp5Mbp1iI6XIILz1/fpLTw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707922948; x=1708527748; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=BuGYPWEJOUTaH5rf6DAQz91oXgKrMbqT0YkEhfKJGuc=; b=ivO45OCBKtWPp67+9ITAzHCygiqZK6iQeielpek91jQmny2wC4UkV+eSzAQE7Jybnh W2jFdNoz7JbNCbiYKJDHv2epEGy5AGtsWdYD7b7LnmQvuTc0dwIDK4nE16mW0bO8l0pC fgi5ivj5GG78To0muUbvHJbX5X26GlQ4l0d/Fd4Ug7qQJaohvVsYUCe7N2J6OrbdCeRp +p+u8Oo6UnKNLCKJmWXMzOl2pVp2zPQvbtdYiojM27FCkOR/G3qWyJG70o0h1RPTvSYg VrqxpePwYlJSdcg6QyMwslUJIxo0XPhHaHDUVHRN+j2VDw27R0xtMIomE7e3A2W2cuWE ye9A== X-Gm-Message-State: AOJu0Yx1DwGoPtGPHTL+CDJLLnyjcUkRYbdicPGTALh8D1G0z2s2+dcc +7ysYmrSHazwmOpxs6fK8CVz8pKIQv/Ram3HVC84IabPNFjXaYhXhfX9+qIEQdM= X-Google-Smtp-Source: AGHT+IHNFmecXRH2jOezFs+xLBqoWq0zVXTtUbqa+I4cM5vGILI35YTnPjzxTvvMRnrpve4xr8FTSw== X-Received: by 2002:a05:6512:1391:b0:511:a2ed:f6c5 with SMTP id fc17-20020a056512139100b00511a2edf6c5mr2382930lfb.18.1707922948343; Wed, 14 Feb 2024 07:02:28 -0800 (PST) X-Forwarded-Encrypted: i=1; AJvYcCXVYYtCtrG9pGYKKSvFMKWFE+/qIvEICmzua5q4ESHeNrm9MWt1QlnrEny9trbfH7G1y+aoz5TC5VgiBOAPKnbiwgqyrwwfD+ApOti4QfTklBDCJuXVdjgjj43SWfgHipjZCeLsieff+w== Date: Wed, 14 Feb 2024 16:02:26 +0100 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Frediano Ziglio Cc: xen-devel@lists.xenproject.org, Jan Beulich , Andrew Cooper , Wei Liu Subject: Re: [PATCH v2] Reduce assembly code size of exception entry points Message-ID: References: <20240214103558.13655-1-frediano.ziglio@cloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240214103558.13655-1-frediano.ziglio@cloud.com> On Wed, Feb 14, 2024 at 10:35:58AM +0000, Frediano Ziglio wrote: > We just pushed a 8-bytes zero and exception constants are > small so we can just write a single byte saving 3 bytes for > instruction. > With ENDBR64 this reduces the size of many entry points from 32 to > 16 bytes (due to alignment). > Similar code is already used in autogen_stubs. Will using movb instead of movl have any performance impact? I don't think we should trade speed for code size, so this needs to be mentioned in the commit message. Thanks, Roger.