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.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 smtp.lore.kernel.org (Postfix) with ESMTPS id 3E617C433FE for ; Fri, 22 Apr 2022 13:23:53 +0000 (UTC) Received: from localhost ([::1]:50114 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nhtGK-00087D-E8 for qemu-devel@archiver.kernel.org; Fri, 22 Apr 2022 09:23:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58572) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nhtEh-0005p0-Q2 for qemu-devel@nongnu.org; Fri, 22 Apr 2022 09:22:12 -0400 Received: from mail-yb1-xb35.google.com ([2607:f8b0:4864:20::b35]:44022) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1nhtEe-00089q-9Q for qemu-devel@nongnu.org; Fri, 22 Apr 2022 09:22:10 -0400 Received: by mail-yb1-xb35.google.com with SMTP id f17so14419491ybj.10 for ; Fri, 22 Apr 2022 06:22:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=krNvCdy5GwksLTiZ6ZXKT0rQ6OUbZa3vyIGCSzCLTf0=; b=r6AAIQYCfRm3Y0rhBt9ML/TCVmDdr+PJ5Pfl/l0xtqLSVjlABDOT8WmNuWcim9F1rm kKodcMelcUW8t3CQvsfusIIplkqCLIbHY4w5cK8Nx08zPWTEUJmyR9wbjH2peFNVDTx5 cejHS3CWT8NhIsEapZqJRZdYuJh4WHJN6rdoJJD7l9TkXZNh2PvPhMblxH5cjSOrcDz3 usZWfg3sn64GmgUazoaLfmVY3Jowlx44Jzpwmj99OZDEj4RydZXpSD9BBJenwRY/QmPZ 83ZxUkgaXo/ZBLy5WPp2WjRGyxAXjgf1x3KkBMujnGub94d0eD5EGyPSeRO728Flvlpw 2CnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=krNvCdy5GwksLTiZ6ZXKT0rQ6OUbZa3vyIGCSzCLTf0=; b=NxXWg7WJR0MiZ9ml45S+gM/73ktSCflv6CmUAh/k9lFH1gBznAaIkMM8ggZkVfrtd7 OCcTnvidTf9BSCZ5XeN6VhyL0sQSFMeQ0c2G/T1cKIf4/eZ/cF4f+QTxMPy2QpGoFzwl pCxtKX98QPx3Vlzmxzao2OxT6ZDaXoeDxyPRsIZMijfQnTsRYhfsoQ2PIjULz2M3utA2 tL0F054KsfUDVNusFmLhGeMiM/xh4R1hYjLd/uZ9oA7xuiHXc1DEKsYESfV/R4TOh5TN w8V2kt15Hq3PmxumGTWivbNKWeiQXOGzTZh+fI95fE8EqavJ0tD1NRLRD3FI2sEL0/d5 v8Kg== X-Gm-Message-State: AOAM532XYzsKGHXQNpQhsPpqWPOmxyTVpckVBHelg+WtQDW8MSYlhxlw hycU/ie3DDPC0CSLrh+JZktelk3MvfsDyAYmBSrLYQ== X-Google-Smtp-Source: ABdhPJyESpwxjqQnip2BVxGKsIN11u3sDAPLdniCewV6MDXdMftrgTTq5BoAeI37Vr3fajp5xQrn8aJY2fVL5cKBAa4= X-Received: by 2002:a25:c60a:0:b0:645:d925:64d3 with SMTP id k10-20020a25c60a000000b00645d92564d3mr1328636ybf.288.1650633726965; Fri, 22 Apr 2022 06:22:06 -0700 (PDT) MIME-Version: 1.0 References: <20220421151735.31996-1-richard.henderson@linaro.org> <20220421151735.31996-54-richard.henderson@linaro.org> In-Reply-To: <20220421151735.31996-54-richard.henderson@linaro.org> From: Peter Maydell Date: Fri, 22 Apr 2022 14:21:55 +0100 Message-ID: Subject: Re: [PATCH v7 53/64] target/nios2: Introduce shadow register sets To: Richard Henderson Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2607:f8b0:4864:20::b35; envelope-from=peter.maydell@linaro.org; helo=mail-yb1-xb35.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, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 21 Apr 2022 at 17:42, Richard Henderson wrote: > > Do not actually enable them so far, in terms of being able > to change the current register set, but add all of the > plumbing to address them. Do not enable them for user-only. > > Add an env->regs pointer that handles the indirection to > the current register set. The naming of the pointer hides > the difference between old and new, user-only and sysemu. > > From the notes on wrprs, which states that r0 must be initialized > before use in shadow register sets, infer that R_ZERO is *not* > hardwired to zero in shadow register sets, but that it is still > read-only. Introduce tbflags bit R0_0 to track that it has been > properly set to zero. Adjust load_gpr to reflect this. > > At the same time we might as well special case crs == 0 to avoid > the indirection through env->regs during translation as well; this > is intended to be the most common case for non-interrupt handlers. > > Init env->regs at reset. > > Signed-off-by: Richard Henderson Reviewed-by: Peter Maydell thanks -- PMM