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=-16.4 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 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 963B5C4743C for ; Fri, 4 Jun 2021 19:18:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 70568613FA for ; Fri, 4 Jun 2021 19:18:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230242AbhFDTUY (ORCPT ); Fri, 4 Jun 2021 15:20:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:56390 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229501AbhFDTUY (ORCPT ); Fri, 4 Jun 2021 15:20:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 36C9E60FF2; Fri, 4 Jun 2021 19:18:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622834317; bh=Td3cMR7nK45iiYWoP6uacaO9FLRb5ILHWTk6aKSJcvM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=j2Ul2eWYwpy3DE6+0Vb1KYIB3jdCQIBvz9LXDfs7hC6HsJDopAQGGlrL1vEa/2Io4 pj/On0QNyXRaRdRABiwcQrtwwKzXCqYn4nuDGzwxiEJ/NWF+/5N5JQxl8qpP14G3e4 FtW4YQaKCh20QO36EkhDiRKe9EtedfGK0eUzXmmAEr5Jt+BMjNMKV+V70HjwzlDLQ1 0p8zRYdvYU5dEfC5oEX88u1+O/tbdngu3sk6TAM6Q0JGjmLYBBSB3NUl9+D8sCQx2J lKUZG2NU6uCQC6RCCcX3GdYEDHYwVoMBKSZd73AbvofdTwyGilrFJzHsbLI6EJ+CAK 9y2i5JiKv8Xyw== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 80F2440EFC; Fri, 4 Jun 2021 16:18:34 -0300 (-03) Date: Fri, 4 Jun 2021 16:18:34 -0300 From: Arnaldo Carvalho de Melo To: Masami Hiramatsu Cc: Ravi Bangoria , Jiri Olsa , linux-kernel@vger.kernel.org, aneesh.kumar@linux.ibm.com, Peter Zijlstra , Ingo Molnar , Namhyung Kim , Ian Rogers Subject: Re: [PATCH 2/2] perf/probe: Report permission error for tracefs error Message-ID: References: <162282064848.448336.15589262399731095367.stgit@devnote2> <162282066829.448336.16156999655071988915.stgit@devnote2> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <162282066829.448336.16156999655071988915.stgit@devnote2> X-Url: http://acmel.wordpress.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Sat, Jun 05, 2021 at 12:31:08AM +0900, Masami Hiramatsu escreveu: > Report permission error for the tracefs access error. > This can happen when non-superuser runs perf probe. > With this patch, perf probe shows the following message. > > $ perf probe -l > No permission to access tracefs. Please run this command again with sudo. > Error: Failed to show event list. > > Signed-off-by: Masami Hiramatsu > --- > tools/perf/util/probe-file.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c > index 52273542e6ef..52d878f5a44d 100644 > --- a/tools/perf/util/probe-file.c > +++ b/tools/perf/util/probe-file.c > @@ -48,6 +48,8 @@ static void print_open_warning(int err, bool uprobe) > uprobe ? 'u' : 'k', config); > } else if (err == -ENOTSUP) > pr_warning("Tracefs or debugfs is not mounted.\n"); > + else if (err == -EACCES) > + pr_warning("No permission to access tracefs. Please run this command again with sudo.\n"); > else > pr_warning("Failed to open %cprobe_events: %s\n", > uprobe ? 'u' : 'k', > @@ -62,6 +64,8 @@ static void print_both_open_warning(int kerr, int uerr) > else if (kerr == -ENOENT && uerr == -ENOENT) > pr_warning("Please rebuild kernel with CONFIG_KPROBE_EVENTS " > "or/and CONFIG_UPROBE_EVENTS.\n"); > + else if (kerr == -EACCES && uerr == -EACCES) > + pr_warning("No permission to access tracefs. Please run this command again with sudo.\n"); > else { > char sbuf[STRERR_BUFSIZE]; > pr_warning("Failed to open kprobe events: %s.\n", This one doesn't look so helpful, as running as root usually will allow things to proceed. 'perf trace' does: ⬢[acme@toolbox pahole]$ perf trace ls Error: No permissions to read /sys/kernel/tracing/events/raw_syscalls/sys_(enter|exit) Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/tracing/' ⬢[acme@toolbox pahole]$ Which would be less drastic than requiring full superuser access. - Arnaldo