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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 136B1C433F5 for ; Wed, 23 Feb 2022 08:00:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238921AbiBWIBC (ORCPT ); Wed, 23 Feb 2022 03:01:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231338AbiBWIBA (ORCPT ); Wed, 23 Feb 2022 03:01:00 -0500 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8D7E7806E for ; Wed, 23 Feb 2022 00:00:33 -0800 (PST) Received: by mail-pl1-x634.google.com with SMTP id bd1so1976005plb.13 for ; Wed, 23 Feb 2022 00:00:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=wNwlylqM8UG+h4dpaoNyh+r+m1r4BIsa//SdX9MQ3a8=; b=ZPPisKGmhHTBx2WsKs0jYw6Oks8a5UDgAHIt8opueNDY+CUdq8RJcRFPbKpNutlWUJ 1m5XqEE2UTB3jV7PMRTWTM3mWfoymZllDK7ChgJrG/eCBCilAbbvHG+sQvhcIZW6LWX2 MefUEMqxPHjxSbl+QKfuywhtyaoBktVIR+IPbCGka2yBRdfCKYgj1xH7joPFOVElmcwq ci3GEsy9NolmqSSPFUeABd6cVM2L8f0UBzf+e15YCOSG0AJaskpQL3QP64jajs/51NRj 9QE3eV+eaz3aNBoItJVnopyNyxYFyAJsJoianMUj9cESsKx7HKoyvYCikmsa+yV+8RU5 8dZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=wNwlylqM8UG+h4dpaoNyh+r+m1r4BIsa//SdX9MQ3a8=; b=syfqM86EXQVSUM5vsoI1sQ5b8KlqZb67Ay4Ublk5+aUPX22Gm7YjNdteMwAA/W9nLR vCXMzG54VTvsLLDgEdHNd1h1StJVqkGRkpMOLUF3YbirgfuIN0KZae3nUbS/TG+bMWoi bnN2riWEYvF78kca3kMgqp0wc1l5M+xLTWKvEE3QRp6SeW7KvTDMzWrWDdYYg3RwsEOx jWmItq6EuI6ulksKX71/VY9+/DyIsjKpwU8A2jR9WhRlttmt16RvMyK6UXttdc35sZLk 2NH2gstR7pAkOE/J+1c6393IS1AgS9Uoiszz2PbC8nMoJjL7SjgqOMX2Sz/qa/UMAVFc XIUg== X-Gm-Message-State: AOAM533WM/Cj2uNBCUTlkhRSE3kmPAhBPvqMo4uhIIPuslL7OccSZk/f HLd9vlBkDHBnTSuLmQK4XAuCy64tOts84A== X-Google-Smtp-Source: ABdhPJwanoqHKILjEIhFMJdUsfeGsDQ/fx0MwTEeS7SIofH6SyT+Shqtkerc+U2jJvrwTyt3XwJDYQ== X-Received: by 2002:a17:903:404a:b0:14f:944f:22eb with SMTP id n10-20020a170903404a00b0014f944f22ebmr16980810pla.21.1645603233357; Wed, 23 Feb 2022 00:00:33 -0800 (PST) Received: from [10.255.215.56] ([139.177.225.242]) by smtp.gmail.com with ESMTPSA id u12-20020a17090a890c00b001b8efcf8e48sm1902444pjn.14.2022.02.23.00.00.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Feb 2022 00:00:33 -0800 (PST) Message-ID: <5d64733b-8d2a-4928-c4dc-ce4f3b5fc561@bytedance.com> Date: Wed, 23 Feb 2022 16:00:27 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [External] Re: [PATCH] arm64/ftrace: Make function graph use ftrace directly Content-Language: en-US To: Steven Rostedt Cc: mingo@redhat.com, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, broonie@kernel.org, songmuchun@bytedance.com, qirui.001@bytedance.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20220222130049.81284-1-zhouchengming@bytedance.com> <20220222105218.28e3d5aa@gandalf.local.home> From: Chengming Zhou In-Reply-To: <20220222105218.28e3d5aa@gandalf.local.home> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/2/22 11:52 下午, Steven Rostedt wrote: > On Tue, 22 Feb 2022 21:00:49 +0800 > Chengming Zhou wrote: > >> As we do in commit 0c0593b45c9b ("x86/ftrace: Make function graph >> use ftrace directly"), we don't need special hook for graph tracer, >> but instead we use graph_ops:func function to install return_hooker. >> >> Since commit 3b23e4991fb6 ("arm64: implement ftrace with regs") add >> implementation for FTRACE_WITH_REGS on arm64, we can easily adopt >> the same optimization on arm64. > > Note. Ideally we want it to hook with DYNAMIC_FTARCE_WITH_ARGS, and not > FTRACE_WITH_REGS. If arm64 is like x86_64, saving all regs at every > function call has a bit more overhead than saving the minimum. The > DYNAMIC_FTRACE_WITH_ARGS, means that the minimum is still saved, but now > exposes the arguments and the stack pointer, which function_graph_tracer > needs. Yes, it would be better to implement DYNAMIC_FTRACE_WITH_ARGS on arm64 too, and this patch just use DYNAMIC_FTRACE_WITH_REGS to install return_hooker for graph tracer, so it's a code cleanup, no performance optimization. Thanks. > > -- Steve > > >> >> Signed-off-by: Chengming Zhou >> ---