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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 C9BCBC433FE for ; Fri, 11 Dec 2020 19:59:32 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 1B60D23EF5 for ; Fri, 11 Dec 2020 19:59:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1B60D23EF5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56596 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1knoZe-0003wz-ST for qemu-devel@archiver.kernel.org; Fri, 11 Dec 2020 14:59:30 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:57668) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1knoSE-0000C1-AT for qemu-devel@nongnu.org; Fri, 11 Dec 2020 14:51:51 -0500 Received: from mail-oi1-x230.google.com ([2607:f8b0:4864:20::230]:34741) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1knoS8-0004N9-VS for qemu-devel@nongnu.org; Fri, 11 Dec 2020 14:51:49 -0500 Received: by mail-oi1-x230.google.com with SMTP id s75so11162009oih.1 for ; Fri, 11 Dec 2020 11:51:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=H+i3t5puj6+ptQxR9CEYaxa9EBma49UqJfXN64ql4zU=; b=ByxJFyBRidh+Du+cyQ+2AxjrULY0lQqPTxiGs4yV0zsg7EsJ3d20s8RC/i9K0I3xJw CBqCQikZBpJGscGNjCqD6XOuDXxwrQdHBktIUMzTznXsKvCr7+IxabapfihLj+0O7F9P 7khJiS64nw+DwbHghRK7sEpFb7OHT5fv+MX6zVZPC+7ru/LkeKWUS2UrNLpGh46ROLUF nuBuUHHWZZV2wJJbNn6TLVs8daBzk4isuwYqnfZBKe9XPwRcNhaNI/hZSprzymYaTPRg uto/tuRteRItQru6PUY0Otr6yExVzYv0t92hYErm2Pgu2ulqqf5KoGbj7SZCJtVJnBFF jmaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=H+i3t5puj6+ptQxR9CEYaxa9EBma49UqJfXN64ql4zU=; b=i18Ws5co9FSRRgRh+OjN75wJCUHvZU6RTeSIxstcrknUo+97rSONQaOgNIcCdLC1nc I3hzcrSvVI1SAVQWNqjwzJYRcF8jcs2XkGSzvdloo6HCFLGdh9vhyXWKUKUy2xUOldA0 EyItNy1cTuuXAPj6m3R+O8WoaarkJpGcwJIIl3Ka29dFqNZ9Ue0y8lloOkt4J8FyFFjE IRdkWgOqKzdG5XE205suyAYUVocz3xyODElNISAgT0G5Zp9SfjU7EVWLZHD8EsUcge4Y xNul9NLbSrq9WU5My4zvoLXkfw/WgP7wvbtlyAbKqtShvjvOpJsTdDwlFxazivp+Fb04 1Qqg== X-Gm-Message-State: AOAM5338mzT8OX90XtZNFsR0Hep4t4YcfrtH3IPy0ZZwLBXWQhjAE4fs 2AB9GigOwbuG448Q0ic2I32l2A== X-Google-Smtp-Source: ABdhPJwntCsX5C1qdAmwmAKYndiJBEm4Z4FLDkFxu8QJzqFIfwW1ByzgldUYnWBJPtXQy5fILmVG8w== X-Received: by 2002:aca:3b57:: with SMTP id i84mr10309259oia.17.1607716302933; Fri, 11 Dec 2020 11:51:42 -0800 (PST) Received: from [10.10.121.52] (fixed-187-189-51-144.totalplay.net. [187.189.51.144]) by smtp.gmail.com with ESMTPSA id 6sm2055335otc.19.2020.12.11.11.51.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Dec 2020 11:51:42 -0800 (PST) Subject: Re: [PATCH 1/2] target/arm: add support for FEAT_DIT, Data Independent Timing To: Rebecca Cran , qemu-devel@nongnu.org References: <20201211051359.3231-1-rebecca@nuviainc.com> <20201211051359.3231-2-rebecca@nuviainc.com> <6dd32a22-e3a6-db57-fc5b-9a3da4e1a709@linaro.org> <284b9f4e-55b7-81a3-f1c5-7f7b6d0c9784@nuviainc.com> From: Richard Henderson Message-ID: <46d7b991-d305-bd2f-91f9-cdc2ee1e73ce@linaro.org> Date: Fri, 11 Dec 2020 13:51:40 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <284b9f4e-55b7-81a3-f1c5-7f7b6d0c9784@nuviainc.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::230; envelope-from=richard.henderson@linaro.org; helo=mail-oi1-x230.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 12/11/20 1:33 PM, Rebecca Cran wrote: > Is the comment in target/arm/op_helper.c:397 still relevant? > > uint32_t HELPER(cpsr_read)(CPUARMState *env) > { >     /* >      * We store the ARMv8 PSTATE.SS bit in env->uncached_cpsr. >      * This is convenient for populating SPSR_ELx, but must be >      * hidden from aarch32 mode, where it is not visible. >      * >      * TODO: ARMv8.4-DIT -- need to move SS somewhere else. >      */ >     return cpsr_read(env) & ~(CPSR_EXEC | PSTATE_SS); > } I forgot about this. So we can't "just" store DIT in uncached_cpsr. I'll let Peter weigh in, but I think it makes sense to move the SS bit somewhere else (e.g. env->pstate) and merge it into SPSR_ELx upon interrupt. While what we're doing here is convenient, it's not architectural, and it would be better to follow GetPSRFromPSTATE pseudocode. r~