From nobody Tue Nov 26 08:33:21 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=linaro.org ARC-Seal: i=1; a=rsa-sha256; t=1709121830; cv=none; d=zohomail.com; s=zohoarc; b=QXbcQN3S5/6Iur3TiIF0+RZn7YDQ37Eey+/lcM+nG+ExeAnxg3et0J+XyNskUtqL1Xq9LP6j+I/AF3Ajyu5Q0/uSEjw4XHXg64G0xtiYL0j0bVfYgRadJqwfGJ7g14UjKEidYNgSbyo03s8dU8golJKszGg3xVNEfUd4GHrsJoY= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1709121830; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=pC0CILfvkT1LAPjD+cy5PSMJ+8YOfVMAkY3CpGh5+Vk=; b=fdyFaLcM333BG22bUV+LmRVkPREbwxHR2LxV7zpVstsZ3+lvmBMASCbGv6iO1IxngxOBn37ZiVsgxSd6tak7RwG/d6hB4aq+puYbwcAqZpH3Z+grM20aAbCYDxSis8sl24eUcOQ8nkf7VnpuEtiZHQ+hLM3Zns+36hobCw1ZEQg= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1709121830134378.87415851227024; Wed, 28 Feb 2024 04:03:50 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rfIeT-0004nA-Lq; Wed, 28 Feb 2024 07:03:10 -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 1rfIeO-0004dm-Bl for qemu-devel@nongnu.org; Wed, 28 Feb 2024 07:03:04 -0500 Received: from mail-lj1-x232.google.com ([2a00:1450:4864:20::232]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1rfIeI-00034h-AZ for qemu-devel@nongnu.org; Wed, 28 Feb 2024 07:03:04 -0500 Received: by mail-lj1-x232.google.com with SMTP id 38308e7fff4ca-2d28387db09so45489231fa.0 for ; Wed, 28 Feb 2024 04:02:57 -0800 (PST) Received: from draig.lan ([85.9.250.243]) by smtp.gmail.com with ESMTPSA id az8-20020adfe188000000b0033d7dd27d97sm14421391wrb.45.2024.02.28.04.02.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Feb 2024 04:02:56 -0800 (PST) Received: from draig.lan (localhost [IPv6:::1]) by draig.lan (Postfix) with ESMTP id 8E2165F92F; Wed, 28 Feb 2024 11:57:04 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1709121776; x=1709726576; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=pC0CILfvkT1LAPjD+cy5PSMJ+8YOfVMAkY3CpGh5+Vk=; b=EzsGqqv/OZUmEcdlXjmGNBRONrKIG5AxkP+ZT5wtEROzkND9WnNCuWEMaiYVzpzzsN C7jqBulZ+swpfDZLNtEIJPSY0qLXn5+3OzN2Jo/sQI6DM6fYXCwbbfJHREdAXtqyHwpF O7HdyNrr1x/q3xDc07HMU/Hd0Ith4UfYGGb/Ft/j7kDdBoDzlqODsO0EkwZu13qVkUPM a9jnVslufT/OYIRJNdUeufBAdp87dEwDJlWyqsiVx3iHr3hzO9Vz/OeMmKcOzxLQATNN pJnAoal0tqcuK6PfsoXTwz4EL/Ww7IFa3FNO/GQHi7L4ns6OP4pB/rTQhMEyh7374o7w 8P9w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709121776; x=1709726576; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=pC0CILfvkT1LAPjD+cy5PSMJ+8YOfVMAkY3CpGh5+Vk=; b=GbxaEl/+tDDIOxK7Pj7vky/0HekHkWTu6YTFIaec+/IRj5mfdP0tIkMvLJiVcUOKZs YuOYbV5m+oUF6bb/DcE8cT0cSJJWYyAEQ0SDZcFhAA+enqNR9GDv718CJ5RPaLZH0I+U PDJCECLeI6zhw9y7H07bMHfRZID9nA9zReXCuDOO/tVj97i92AMRYlrHy/OFWloNuRVv /VnEa5Gthx1bbiLkYKWjoGdnIy8XiuUPjHY3L4fGJmBsboBDLHVCPYhRuHLuClYUGlPr /0Gag2SXL2D8286SvqZNYlYGkMBeRKgDUpHnWSIQ7pvh+UghCMmcx9xCXR/0WAsPfqaF HM+w== X-Gm-Message-State: AOJu0Yxw9DXsuzvSfDNUnVpWTknZrZDcBI/WkDurF3SAYuTG6nMVMlZE E7D6RWvqQhNi70saiqMMCiEk//Mrl+52GwwLTJ5GSOiYCWE65dTS2I8vALtisR4= X-Google-Smtp-Source: AGHT+IHCBKihnQavink9cJUSVWNc3sVpt/jxZHShqNLLHcyyWdb2SHGoXbwxwb+WbV/WK+dJSM6Z+w== X-Received: by 2002:a2e:6a06:0:b0:2d1:1ef3:3c84 with SMTP id f6-20020a2e6a06000000b002d11ef33c84mr7438014ljc.28.1709121776728; Wed, 28 Feb 2024 04:02:56 -0800 (PST) From: =?UTF-8?q?Alex=20Benn=C3=A9e?= To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Alex=20Benn=C3=A9e?= , Pierrick Bouvier , Richard Henderson , Paolo Bonzini , Alexandre Iooss , Mahmoud Mandour Subject: [PULL 28/29] docs/devel: document some plugin assumptions Date: Wed, 28 Feb 2024 11:57:00 +0000 Message-Id: <20240228115701.1416107-29-alex.bennee@linaro.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240228115701.1416107-1-alex.bennee@linaro.org> References: <20240228115701.1416107-1-alex.bennee@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a00:1450:4864:20::232; envelope-from=alex.bennee@linaro.org; helo=mail-lj1-x232.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, T_SCC_BODY_TEXT_LINE=-0.01, T_SPF_TEMPERROR=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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1709121831184100001 While we attempt to hide implementation details from the plugin we shouldn't be totally obtuse. Let the user know what they can and can't expect with the various instrumentation options. Reviewed-by: Pierrick Bouvier Signed-off-by: Alex Benn=C3=A9e Message-Id: <20240227144335.1196131-29-alex.bennee@linaro.org> diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst index 535a74684c5..9cc09d8c3da 100644 --- a/docs/devel/tcg-plugins.rst +++ b/docs/devel/tcg-plugins.rst @@ -112,6 +112,55 @@ details are opaque to plugins. The plugin is able to q= uery select details of instructions and system configuration only through the exported *qemu_plugin* functions. =20 +However the following assumptions can be made: + +Translation Blocks +++++++++++++++++++ + +All code will go through a translation phase although not all +translations will be necessarily be executed. You need to instrument +actual executions to track what is happening. + +It is quite normal to see the same address translated multiple times. +If you want to track the code in system emulation you should examine +the underlying physical address (``qemu_plugin_insn_haddr``) to take +into account the effects of virtual memory although if the system does +paging this will change too. + +Not all instructions in a block will always execute so if its +important to track individual instruction execution you need to +instrument them directly. However asynchronous interrupts will not +change control flow mid-block. + +Instructions +++++++++++++ + +Instruction instrumentation runs before the instruction executes. You +can be can be sure the instruction will be dispatched, but you can't +be sure it will complete. Generally this will be because of a +synchronous exception (e.g. SIGILL) triggered by the instruction +attempting to execute. If you want to be sure you will need to +instrument the next instruction as well. See the ``execlog.c`` plugin +for examples of how to track this and finalise details after execution. + +Memory Accesses ++++++++++++++++ + +Memory callbacks are called after a successful load or store. +Unsuccessful operations (i.e. faults) will not be visible to memory +instrumentation although the execution side effects can be observed +(e.g. entering a exception handler). + +System Idle and Resume States ++++++++++++++++++++++++++++++ + +The ``qemu_plugin_register_vcpu_idle_cb`` and +``qemu_plugin_register_vcpu_resume_cb`` functions can be used to track +when CPUs go into and return from sleep states when waiting for +external I/O. Be aware though that these may occur less frequently +than in real HW due to the inefficiencies of emulation giving less +chance for the CPU to idle. + Internals --------- =20 --=20 2.39.2