From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751981AbbFZGXp (ORCPT ); Fri, 26 Jun 2015 02:23:45 -0400 Received: from e23smtp08.au.ibm.com ([202.81.31.141]:33202 "EHLO e23smtp08.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750993AbbFZGXg (ORCPT ); Fri, 26 Jun 2015 02:23:36 -0400 X-Helo: d23dlp01.au.ibm.com X-MailFrom: zhlcindy@linux.vnet.ibm.com X-RcptTo: linux-kernel@vger.kernel.org Message-ID: <558CEFA5.4040502@linux.vnet.ibm.com> Date: Fri, 26 Jun 2015 14:22:29 +0800 From: Li Zhang User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: Li Zhang CC: acme@kernel.org, mingo@redhat.com, sukadev@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/1] perf tools: Check access permission when reading symbol files References: <1434704253-2632-1-git-send-email-zhlcindy@linux.vnet.ibm.com> In-Reply-To: <1434704253-2632-1-git-send-email-zhlcindy@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15062606-0029-0000-0000-000001BE2723 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ping ? On 2015年06月19日 16:57, Li Zhang wrote: > There 2 problems when reading symbols files: > > * It doesn't report any errors even if when users specify symbol > files which don't exist with --kallsyms or --vmlinux. The result > just shows the address without symbols, which is not what is expected. > So it's better to report errors and exit the program. > > * When using command perf report --kallsyms=/proc/kallsyms with a > non-root user, symbols are resolved. Then select one symbol and > annotate it, it reports the error as the following: > Can't annotate __clear_user: No vmlinux file with build id xxx was > found. > > The problem is caused by reading /proc/kcore without access permission. > /proc/kcore requires CAP_SYS_RAWIO capability to access, so it needs to > change access permission to allow a specific user to read /proc/kcore or > use root to execute the perf command. > > This patch is to report errors when symbol files specified by users > don't exist. And check access permission of /proc/kcore when reading it. > > Signed-off-by: Li Zhang > --- > > v3 -> v2: > * Add checking symbol files when user specify these files. > * Report an error to users when open fails. Suggested by Sukar > > v2 -> v1: > * Report one useful message to users about the access permision, > then go back to the tools. Suggested by Arnaldo Carvalho de Melo. > > tools/perf/builtin-report.c | 11 +++++++++++ > tools/perf/util/symbol.c | 5 ++++- > 2 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c > index 476cdf7..1c353b1 100644 > --- a/tools/perf/builtin-report.c > +++ b/tools/perf/builtin-report.c > @@ -731,6 +731,17 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused) > > argc = parse_options(argc, argv, options, report_usage, 0); > > + if (symbol_conf.vmlinux_name && > + access(symbol_conf.vmlinux_name, R_OK)) { > + pr_err("Invalid file: %s\n", symbol_conf.vmlinux_name); > + return -EINVAL; > + } > + if (symbol_conf.kallsyms_name && > + access(symbol_conf.kallsyms_name, R_OK)) { > + pr_err("Invalid file: %s\n", symbol_conf.kallsyms_name); > + return -EINVAL; > + } > + > if (report.use_stdio) > use_browser = 0; > else if (report.use_tui) > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > index 201f6c4c..46aa93d 100644 > --- a/tools/perf/util/symbol.c > +++ b/tools/perf/util/symbol.c > @@ -1126,8 +1126,11 @@ static int dso__load_kcore(struct dso *dso, struct map *map, > INIT_LIST_HEAD(&md.maps); > > fd = open(kcore_filename, O_RDONLY); > - if (fd < 0) > + if (fd < 0) { > + pr_err("%s requires CAP_SYS_RAWIO capability to access.\n", > + kcore_filename); > return -EINVAL; > + } > > /* Read new maps into temporary lists */ > err = file__read_maps(fd, md.type == MAP__FUNCTION, kcore_mapfn, &md, -- Li Zhang IBM China Linux Technology Centre