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 C2126C433F5 for ; Fri, 28 Jan 2022 20:40:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351569AbiA1Uku (ORCPT ); Fri, 28 Jan 2022 15:40:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351288AbiA1Ujx (ORCPT ); Fri, 28 Jan 2022 15:39:53 -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 4B2F4C061751 for ; Fri, 28 Jan 2022 12:39:53 -0800 (PST) Received: by mail-pj1-x1035.google.com with SMTP id o64so7467793pjo.2 for ; Fri, 28 Jan 2022 12:39:53 -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=rtMqs+0t0LNCgzeXJAek0TSVqeINn0O3hd/R613R5/8=; b=kArmkAHUM6o9YQWhMV6kun53D3KQpvPbMcXVFT/oWTdI3HcDAWQUKgPF0IUUsNYY2u k1rK1neycm85tlbqWRty+PCsp+k+jlLOluLwUlvFHXyt0wCCkBDeZfQqch4RLi2pAL8w pJflfNg6dHzmlmyJwWGI57FV0JcjVU5yEZ6RYAFYT/oprGioSPSicRB4EPhOKoeu1ASU X03BnrsoG5wZZzDomyAFXrKPg5AOSvmmopI7ij1fR9cfTcJxCsB0Cu+jFWUcdVk5A7CI RHCiWWD9ZvIzL1+vxID0hol+ohZJnKsJaOxkQ27zSZllFH/Rwn3eGoyVyQTATs9SJb7P Zhkw== 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=rtMqs+0t0LNCgzeXJAek0TSVqeINn0O3hd/R613R5/8=; b=sm+qLJp+4lb6KwLxnp4nnUvdeWfWEKX3YgMWH5nhewMv6G6OyBJCG4PSdVYHZToYuE 9t3v+KbhG1NpafFZyPXNBEGfkXsUIwYUpP2IGcmfVTIisxb2M2ZGni50Kxc+4yYF55qS ndrh9ZrLz3XjK/IMrgPeDABq9aOLY8HdIdrx6b9QSzrs5euRP3QEb5EtR58yaINqykFh Y4bvoUw6GASHUnI18L6BUSt3ebGeuiI0WX9FGJX2/+qFkJoHVoRWmJ6F6+i2Oq2u5EcH HmeRnEnhammmthfLSEXyb9bzeA8TJAytjbgRrNsKoMcyGrqz2smQHly78LfviktjdSXF 1BWQ== X-Gm-Message-State: AOAM531lHrJABWBsbPbcOF85rizxSi0sKGCOLAyREIXdfFlFloem7T6J AN52tDg7+Ou7xwN9CDpMC0Y= X-Google-Smtp-Source: ABdhPJwzkQExiaV8hKBN6atyN/p0+WjjAHZt6sxoEei+r6kFLpww+pbe+s2nzSfor7uzZz4B3NzZHg== X-Received: by 2002:a17:90b:380f:: with SMTP id mq15mr21778403pjb.96.1643402392696; Fri, 28 Jan 2022 12:39:52 -0800 (PST) Received: from balhae.hsd1.ca.comcast.net ([2601:647:4800:c6f0:f13b:bc2c:fac:4a86]) by smtp.gmail.com with ESMTPSA id k3sm11235428pfu.180.2022.01.28.12.39.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Jan 2022 12:39:52 -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 0/3] Handle chroot tasks properly (v1) Date: Fri, 28 Jan 2022 12:39:47 -0800 Message-Id: <20220128203950.3371061-1-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. 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-v1' branch at git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git Thanks, Namhyung Namhyung Kim (3): 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