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 2E74FC54E76 for ; Tue, 17 Jan 2023 18:33:26 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pHqlq-0002Bz-7z; Tue, 17 Jan 2023 13:33:18 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pHqln-00023w-65 for qemu-devel@nongnu.org; Tue, 17 Jan 2023 13:33:16 -0500 Received: from mail-wr1-x42e.google.com ([2a00:1450:4864:20::42e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1pHqll-0007bD-Mg for qemu-devel@nongnu.org; Tue, 17 Jan 2023 13:33:14 -0500 Received: by mail-wr1-x42e.google.com with SMTP id r30so7131564wrr.10 for ; Tue, 17 Jan 2023 10:33:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:message-id:in-reply-to:date :subject:cc:to:from:user-agent:references:from:to:cc:subject:date :message-id:reply-to; bh=7QBm1v9hxSrl/d32860bpCXsXOQ048x+gyZ+W38wko8=; b=w7kMnZk2FJpr6OQ01mXSMCE9mQ+qf3XLxPnxh6dXXoHRBpwyRQOam9sYhbtdBM4ksH gsESynT1f9QgEESFRb9DgXCCSLImyR4K84lZgofyXBHHT4C9QjdyhZIGkheN8ypalAZV jS6rGfgwfjlloj/Y3G8aGF3MrCXyl7mFw7zd+aY93t6eYwLbYr2SiaxGh3X7ZT5yZy1L FLQq5nrrx/HlsSmxPd3wqdSmDoC7s1m7KJi+InKleTjSEtY+eij9hHM1yY5CLcwvmYl4 ESURT8g8gOJ6ZNqG8wcSP596XvhEY4xRsfZYioXypatYWtiAlmYzMmEPNI/lLZZ5WZoK K5EA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:in-reply-to:date :subject:cc:to:from:user-agent:references:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=7QBm1v9hxSrl/d32860bpCXsXOQ048x+gyZ+W38wko8=; b=CK4amuxKev4hXzuX7GrBhhBa0vyMd6hcV82FiKRIJZc2QDvEnxpiKJEvgYTCiJBOo9 5h35zCDhdoTImfBH+nfJkBbejMNzTUCTBkafib82EDmvCthDTKXb8rivImZs+fj0KBkl W+xXBCc3etQNmpRpQSM6pyUMcbmPXM1JOxUSQIV4DvAHtBz7mlrywkRTM0MHSgmXQusy B0JZi6ruLGTScCVRTGMoiqSLQqswoU/6uJQ1OKhSQjNQtQ+w4G5wCTpd4x5SAm3Lkj34 n/XYpAf+L7yqEiJyuKnFHC+N1ifwYJiZVXEVC7xwilsjj87OY7HwFmY45HtMMLG2ZWBh ByLg== X-Gm-Message-State: AFqh2kr9wH8woplS5naFXtqV9GP4jPiXEugIx1hxTbH9YKzh3rcpA6+H T73zk2BQKhDUoODkAQbm09IdP+72xecpYlZJ X-Google-Smtp-Source: AMrXdXsP0mCwQK2NOpRBg+37+s3I6VL3HmQgYeF4YdkRx5xV3sM3kBYKK0JQLp3/+sdkbOE2HlckFw== X-Received: by 2002:adf:f68e:0:b0:2bd:d966:8002 with SMTP id v14-20020adff68e000000b002bdd9668002mr3598721wrp.8.1673980392187; Tue, 17 Jan 2023 10:33:12 -0800 (PST) Received: from zen.linaroharston ([185.81.254.11]) by smtp.gmail.com with ESMTPSA id e20-20020a5d5954000000b002be099f78c0sm5124681wri.69.2023.01.17.10.33.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Jan 2023 10:33:11 -0800 (PST) Received: from zen (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id 6494C1FFB7; Tue, 17 Jan 2023 18:33:11 +0000 (GMT) References: <20230109014248.2894281-1-richard.henderson@linaro.org> <20230109014248.2894281-20-richard.henderson@linaro.org> User-agent: mu4e 1.9.15; emacs 29.0.60 From: Alex =?utf-8?Q?Benn=C3=A9e?= To: Richard Henderson Cc: qemu-devel@nongnu.org Subject: Re: [PATCH v2 19/22] tcg/sparc64: Reorg goto_tb implementation Date: Tue, 17 Jan 2023 18:33:03 +0000 In-reply-to: <20230109014248.2894281-20-richard.henderson@linaro.org> Message-ID: <87h6wp1060.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::42e; envelope-from=alex.bennee@linaro.org; helo=mail-wr1-x42e.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 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Richard Henderson writes: > The old sparc64 implementation may replace two insns, which leaves > a race condition in which a thread could be stopped at a PC in the > middle of the sequence, and when restarted does not see the complete > address computation and branches to nowhere. > > The new implemetation replaces only one insn, swapping between a > direct branch and a direct call. The TCG_REG_TB register is loaded > from tb->jmp_target_addr[] in the delay slot. > > Signed-off-by: Richard Henderson Reviewed-by: Alex Benn=C3=A9e --=20 Alex Benn=C3=A9e Virtualisation Tech Lead @ Linaro