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=-5.4 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 9F78AC433DF for ; Tue, 13 Oct 2020 20:07:10 +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 D176620BED for ; Tue, 13 Oct 2020 20:07:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="HL4CNVkh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D176620BED 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]:53812 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kSQZg-0004Gi-NP for qemu-devel@archiver.kernel.org; Tue, 13 Oct 2020 16:07:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48800) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kSQZ5-0003kS-4p for qemu-devel@nongnu.org; Tue, 13 Oct 2020 16:06:31 -0400 Received: from mail-pj1-x1041.google.com ([2607:f8b0:4864:20::1041]:35178) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kSQZ3-0005LC-Cu for qemu-devel@nongnu.org; Tue, 13 Oct 2020 16:06:30 -0400 Received: by mail-pj1-x1041.google.com with SMTP id h4so45364pjk.0 for ; Tue, 13 Oct 2020 13:06:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=tFP9/oVxNxD5L14FkZIvJ7f+2CkBXItmIACKqHNyNWg=; b=HL4CNVkhB0SywKAJa4egrbGm0lPJMAJ1hXM2gF7ltcHuCcNgCvbSa8RvJJEAWS20UJ ItpWlqccdQFtwW59nIwHkTcyf5JEb9wP/QrSiOJ7q+AqGl+vlmTXaic6ClE3ZH9tmOL1 eDRpH/2w2pX1xNCLuBmwbGeONqSS6Xmd5YOTZ++WrVKyF+i+XZwHJZTAc3yX0EQPfIbF xbAxTFir3AKRnFbsqIvi/YahTjLSMAdokimU+496FX8yVocJyByKVnkXIyQUJ84JHSnS p26G7ywLQpWS5S5owHNFa2LGqzT4nGuj/E/PazDhFeb2tgWdz8/4+3S5wm7h4btMykGm meeA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=tFP9/oVxNxD5L14FkZIvJ7f+2CkBXItmIACKqHNyNWg=; b=irvJizcrf8gMcQ7Q7JITT6nziLHjCoqA/+EKddUE6cF4vRYsMzw5jWrt+WUjlrH5AV 1x+ElaikFl9RBYCRnl4nY2CpG1HiVNCL7CQTwy9u0VwKWM98o5Q5l29AaMP7IHq1yl7W m9SwnZeTzv5nCS8v5gANmdLm5UEpRt01q/I8R/1P8NapYi0drBDxnzP75+vjpXRRa+NQ oHPOZdd1+JvbZSDVC2pugKPCzGoze+GYbzdP6PJkVEiRErvUS1SYMzMD0alJ1mqzagQk uksX7nKMKQXyizuVBFhPgfmTVRRfIjFtzaPIBIPoZC5lg/NmhRtsPQFVc9NyKexaK6NS JN8g== X-Gm-Message-State: AOAM5306a7pybRMsmhq+GBKEhEenjR9OTBZqgYgOYXbvlhdegaheb+k6 NAi3BMeibWWli8p8Dn+c+LbWJCk8H/2x+g== X-Google-Smtp-Source: ABdhPJwH4rzSmUvLL5ok3LTUsW+pLdc6njyXO+k8UyIBPx+a6GgR72uPFtF87Lusl5fSIPAoMQ2Zpg== X-Received: by 2002:a17:90a:dc07:: with SMTP id i7mr25101pjv.111.1602619587570; Tue, 13 Oct 2020 13:06:27 -0700 (PDT) Received: from [192.168.1.11] ([71.212.141.89]) by smtp.gmail.com with ESMTPSA id z20sm515191pfn.39.2020.10.13.13.06.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 13 Oct 2020 13:06:26 -0700 (PDT) Subject: Re: [PATCH 09/10] target/arm: Implement FPSCR.LTPSIZE for M-profile LOB extension To: Peter Maydell , qemu-arm@nongnu.org, qemu-devel@nongnu.org References: <20201012153746.9996-1-peter.maydell@linaro.org> <20201012153746.9996-10-peter.maydell@linaro.org> From: Richard Henderson Message-ID: Date: Tue, 13 Oct 2020 13:06:21 -0700 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: <20201012153746.9996-10-peter.maydell@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::1041; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x1041.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/12/20 8:37 AM, Peter Maydell wrote: > @@ -198,8 +200,14 @@ void HELPER(vfp_set_fpscr)(CPUARMState *env, uint32_t val) > /* > * M profile FPSCR is RES0 for the QC, STRIDE, FZ16, LEN bits > * and also for the trapped-exception-handling bits IxE. > + * From v8.1M with the low-overhead-loop extension bits > + * [18:16] are used for LTPSIZE and (since we don't implement > + * MVE) always read as 4 and ignore writes. > */ > val &= 0xf7c0009f; > + if (cpu_isar_feature(aa32_lob, cpu)) { > + val |= 4 << 16; > + } > } > > vfp_set_fpscr_to_host(env, val); > @@ -212,9 +220,18 @@ void HELPER(vfp_set_fpscr)(CPUARMState *env, uint32_t val) > * (which are stored in fp_status), and the other RES0 bits > * in between, then we clear all of the low 16 bits. > */ > - env->vfp.xregs[ARM_VFP_FPSCR] = val & 0xf7c80000; > - env->vfp.vec_len = (val >> 16) & 7; > - env->vfp.vec_stride = (val >> 20) & 3; > + if (cpu_isar_feature(aa32_lob, cpu)) { > + /* > + * M-profile low-overhead-loop extension: [18:16] are LTPSIZE > + * and we keep them in vfp.xregs[]. > + */ > + env->vfp.xregs[ARM_VFP_FPSCR] = val & 0xf7cf0000; > + } else { > + /* Those bits might be the old-style short vector length/stride */ > + env->vfp.xregs[ARM_VFP_FPSCR] = val & 0xf7c80000; > + env->vfp.vec_len = (val >> 16) & 7; > + env->vfp.vec_stride = (val >> 20) & 3; > + } I think these two sets of masking are confusing. Perhaps usefully rearranged as if (!fp16) { val &= ~fz16; } vfp_set_fpscr_to_host(env, val); if (!m-profile) { vec_len = extract32(val, 16, 3); vec_stride = extract32(val, 20, 2); } val &= 0xf7c80000; if (lob) { val |= 4 << 16; } fpscr = val; Which then obviates the next patch. r~