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 EF2EEC433EF for ; Wed, 2 Feb 2022 07:08:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230060AbiBBHIc (ORCPT ); Wed, 2 Feb 2022 02:08:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54546 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229878AbiBBHIb (ORCPT ); Wed, 2 Feb 2022 02:08:31 -0500 Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F1C3C06173B for ; Tue, 1 Feb 2022 23:08:31 -0800 (PST) Received: by mail-pj1-x1035.google.com with SMTP id s61-20020a17090a69c300b001b4d0427ea2so5915759pjj.4 for ; Tue, 01 Feb 2022 23:08:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=J3JQTLsN4TUWXq+11AQA6HaRBL7yUQ8UUNf/bjPP2sw=; b=gBooyEowC9KX+DVIUdtnfC1zaMjq2bIY6R6DnGobUlUZ37R+D2UNCiqp6HkmLQ7qf3 rnevRMKeSIs/Dr9uVXqn/UJ0yPcWA2Bwc5Oul0c+fTntBcX4700jji9hoN/pODPhJdyE d/CLo7g+NwrK87pj/NR1dI7h3bc9pB7Zn29Kd9nmGnaXezFqFkYjM56YVTNVxLMYN2H9 yOt5E5MHUnD7FmGrlVopGEfCJIP6JGTOl5w7/VN2lkuYc5ljRMRIV5Gp51/l7jSd3T17 rtK6j05fzaOxOSEsWyq/yLK9yhqbGxM1rCGOxxMaRVoLYMFJ15vQOT1KYy6r9QD3ciUr 3MXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :mime-version:content-transfer-encoding; bh=J3JQTLsN4TUWXq+11AQA6HaRBL7yUQ8UUNf/bjPP2sw=; b=vjx6zv52ikRpj418oXFv2zKohIiyQtJK4IlIxN/2MiW5QTgzkCh/tgt0kjJ08QspQX TMS5DXM1SYl5sb2COG8LE0t8BUwE4N6KTZ7uD2zwIubzMwJSKJQctc4l5T8/YcAVmJQF KHG9cXMimBW17KdkKzNzC3yNJAOgmhL2bji7xCdrUMoiYegofL9JhgyDlO4i/ds/TzP/ xHxFmxaKd0F3csR7cYt1RSo7s0hDqz+ioHLpsWd6iafeJih+wyFUcZ7oYq+ACweZgclT rgsWY6xvgON+F1TVxgsksoLMYySMGxfiMeoW9J9Vy+NVRZ8kPYvYrOD4i6uTrQRznn0D 0Fug== X-Gm-Message-State: AOAM5325NWEzH5WcBt4810PQP63/1ieqpj6+7eOkX9V14PPeqquMgtfC 8Hwd5QHrF9Vx8+i96ZqDFMc= X-Google-Smtp-Source: ABdhPJx/pntocgiCGlqF+6TiXN9dvs0T5AZf4M/lkOBaHxCSc+Uu1Rfsj45QOD/7pui5KCKip9qoAQ== X-Received: by 2002:a17:903:234c:: with SMTP id c12mr28356589plh.55.1643785710896; Tue, 01 Feb 2022 23:08:30 -0800 (PST) Received: from balhae.hsd1.ca.comcast.net ([2601:647:4800:c6f0:9c9f:e426:5704:d42b]) by smtp.gmail.com with ESMTPSA id e15sm4936879pjd.52.2022.02.01.23.08.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Feb 2022 23:08:30 -0800 (PST) Sender: Namhyung Kim From: Namhyung Kim To: Arnaldo Carvalho de Melo , Jiri Olsa Cc: Ingo Molnar , Peter Zijlstra , LKML , Andi Kleen , Ian Rogers Subject: [PATCH 0/4] Handle chroot tasks properly (v2) Date: Tue, 1 Feb 2022 23:08:24 -0800 Message-Id: <20220202070828.143303-1-namhyung@kernel.org> X-Mailer: git-send-email 2.35.0.rc2.247.g8bbb082509-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, I found that perf tools don't work well with tasks in a chroot. The filenames in MMAP record are from the root directory of the task so it's different than what it sees from outside. * changes in v2) - add Jiri's Acked-by - split stderr setup for objdump I've tested it with a simple program (myprog - statically built) which just consumes cpu cycles in a loop for a while (default 1 sec, can by overridden by a command-line argument). # cd $HOME # mkdir -p myroot/bin # cp myprog myroot/bin # perf record chroot myroot myprog # perf report -D | grep MMAP | grep myprog 2084916774977911 0xa2e4 [0x70]: PERF_RECORD_MMAP2 3363818/3363818: \ [0x401000(0x80000) @ 0x1000 fe:01 4346398 2543719070]: r-xp /bin/myprog So it's reported as /bin/myprog and then it's unable to symbolize the samples. It seems hard to fix it for the above use case as the record ended after the task exited. It cannot know the root directory of the task anymore. But we can fix it for real-time use cases like perf top or pipe-mode at least. I tested it again with the following command. # perf record -o- chroot myroot myprog | perf report -i- ... # # Overhead Command Shared Object Symbol # ........ ....... ................. ................................ # 46.02% myprog myprog [.] 0x000000000000178a 36.71% myprog myprog [.] 0x0000000000001792 17.12% myprog myprog [.] 0x000000000000178e 0.05% myprog myprog [.] 0x0000000000001796 0.05% chroot ld-2.33.so [.] intel_check_word.constprop.0 The symbols are not resolved because it failed to load the symbol table as it didn't find the file in the given path. So I modified the code to try a new name prepended with the task's root directory when it's not "/". With this change, I can see the symbols of myprog. In fact, it depends on timing if perf report hits the file before the task is gone. Increasing the loop time to 3 sec helped it to get symbols reliably. # perf record -o- chroot myroot myprog 3 | perf report -i- ... # # Overhead Command Shared Object Symbol # ........ ....... ................. ............................. # 99.83% myprog myprog [.] loop 0.04% chroot [kernel.kallsyms] [k] fxregs_fixup 0.04% chroot [kernel.kallsyms] [k] rsm_load_seg_32 0.03% chroot [kernel.kallsyms] [k] show_cpuinfo_cur_freq 0.01% myprog [kernel.kallsyms] [k] alarmtimer_fired I also found that perf inject and perf annotate need the similar changes. You can get it from 'perf/dso-chroot-v2' branch at git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git Thanks, Namhyung Namhyung Kim (4): perf annotate: Set error stream of objdump process for TUI perf tools: Try chroot'ed filename when opening dso/symbol perf inject: Try chroot directory when reading build-id perf annotate: Try chroot filename for objdump tools/perf/builtin-inject.c | 10 ++++++++++ tools/perf/util/annotate.c | 11 +++++++++++ tools/perf/util/dso.c | 15 +++++++++++++-- tools/perf/util/dsos.c | 13 +++++++++++++ tools/perf/util/symbol.c | 10 ++++++++++ tools/perf/util/util.c | 31 +++++++++++++++++++++++++++++++ tools/perf/util/util.h | 2 ++ 7 files changed, 90 insertions(+), 2 deletions(-) base-commit: e783362eb54cd99b2cac8b3a9aeac942e6f6ac07 -- 2.35.0.rc2.247.g8bbb082509-goog