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 X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4AE7CC47082 for ; Wed, 26 May 2021 14:51:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2160E613F1 for ; Wed, 26 May 2021 14:51:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235145AbhEZOxG (ORCPT ); Wed, 26 May 2021 10:53:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:49596 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235077AbhEZOxF (ORCPT ); Wed, 26 May 2021 10:53:05 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 837B1613B0; Wed, 26 May 2021 14:51:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622040693; bh=q+C2OhfEzhvJRz37H2GbJ1ehvlpy634ux7zEZguaxBk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RhxCwRfd2fvBHl+15tMgD7vNuliCOJLce1otPWSZXSADVoEIa1sSAafq72+rBwsTp PxyE8CXuCTErAONVMUmkGwFIQAbj336XmHJjTmEAKIQfA1AfAGRuWDYChnYX1U086n J5E6DysobqoWxHNs7/j4PCdbWmqgA71/svmDr/k3IQmP5PNz6TRfnUQEU7LpIalaXA rDYdlFnywBbxM4CLHymM3LmzI4R2q0LYqtkGc0A5BpdO+QFlZxU4ZoBXXF0LNdGiw/ rhumeBJKoxxyKjBJ+kqy3vLoEGCvubeCtenjjs/CxHypamd/rEsebcV+DtDiX9CdYK x9Wm06D59cU+w== From: Masami Hiramatsu To: Arnaldo Carvalho de Melo , acme@kernel.org Cc: Ravi Bangoria , Jiri Olsa , jolsa@redhat.com, Masami Hiramatsu , linux-kernel@vger.kernel.org, "Aneesh Kumar K . V" Subject: [PATCH v2] tools/perf: doc: Add permission and sysctl notice Date: Wed, 26 May 2021 23:51:29 +0900 Message-Id: <162204068898.388434.16842705842611255787.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <162201967838.287555.4257117900130102987.stgit@devnote2> References: <162201967838.287555.4257117900130102987.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a section to notify the permission and sysctl setting for perf probe. And fix some indentations. Reported-by: Ravi Bangoria Signed-off-by: Masami Hiramatsu --- Changes in v2: - Add tracefs remount option for --list command. - Mention uprobe case for kptr_restrict and vmlinux/debuginfo permission. --- tools/perf/Documentation/perf-probe.txt | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt index ed3ecfa422e1..080981d38d7b 100644 --- a/tools/perf/Documentation/perf-probe.txt +++ b/tools/perf/Documentation/perf-probe.txt @@ -226,7 +226,7 @@ So, "source.c:100-120" shows lines between 100th to l20th in source.c file. And LAZY MATCHING ------------- - The lazy line matching is similar to glob matching but ignoring spaces in both of pattern and target. So this accepts wildcards('*', '?') and character classes(e.g. [a-z], [!A-Z]). +The lazy line matching is similar to glob matching but ignoring spaces in both of pattern and target. So this accepts wildcards('*', '?') and character classes(e.g. [a-z], [!A-Z]). e.g. 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on. @@ -235,8 +235,8 @@ This provides some sort of flexibility and robustness to probe point definitions FILTER PATTERN -------------- - The filter pattern is a glob matching pattern(s) to filter variables. - In addition, you can use "!" for specifying filter-out rule. You also can give several rules combined with "&" or "|", and fold those rules as one rule by using "(" ")". +The filter pattern is a glob matching pattern(s) to filter variables. +In addition, you can use "!" for specifying filter-out rule. You also can give several rules combined with "&" or "|", and fold those rules as one rule by using "(" ")". e.g. With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar". @@ -295,6 +295,19 @@ Add a probe in a source file using special characters by backslash escape ./perf probe -x /opt/test/a.out 'foo\+bar.c:4' +PERMISSIONS AND SYSCTL +---------------------- +Since perf probe depends on ftrace (tracefs) and kallsyms (/proc/kallsyms), you have to care about the permission and some sysctl knobs. + + - Since tracefs and kallsyms requires root or privileged user to access it, the following perf probe commands also require it; --add, --del, --list (except for --cache option) + + - The system admin can remount the tracefs with 755 (`sudo mount -o remount,mode=755 /sys/kernel/tracing/`) to allow unprivileged user to run the perf probe --list command. + + - /proc/sys/kernel/kptr_restrict = 2 (restrict all users) also prevents perf probe to retrieve the important information from kallsyms. You also need to set to 1 (restrict non CAP_SYSLOG users) for the above commands. Since the user-space probe doesn't need to access kallsyms, this is only for probing the kernel function (kprobes). + + - Since the perf probe commands read the vmlinux (for kernel) and/or the debuginfo file (including user-space application), you need to ensure that you can read those files. + + SEE ALSO -------- linkperf:perf-trace[1], linkperf:perf-record[1], linkperf:perf-buildid-cache[1]