From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>,
Jiri Olsa <jolsa@kernel.org>,
linux-kernel@vger.kernel.org, aneesh.kumar@linux.ibm.com,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Ian Rogers <irogers@google.com>
Subject: Re: [PATCH] perf probe: Provide more detail with relocation warning
Date: Wed, 2 Jun 2021 10:15:37 -0300 [thread overview]
Message-ID: <YLeEeQkXd6vxZo0A@kernel.org> (raw)
In-Reply-To: <20210602211248.1e3e9b4f65261ec17c549406@kernel.org>
Em Wed, Jun 02, 2021 at 09:12:48PM +0900, Masami Hiramatsu escreveu:
> On Wed, 2 Jun 2021 08:52:41 -0300 Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> > Em Wed, May 26, 2021 at 11:20:20PM +0900, Masami Hiramatsu escreveu:
> > > On Wed, 26 May 2021 09:56:29 -0300 Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> > > > I.e. go the extra step and show what the current value is and what it
> > > > needs to be to achieve what is being attempted.
> > > > IOW combine error message with relevant documentation, to save steps.
> > > > See what 'perf top' does for an unpriv user:
> > > > $ perf top --stdio
> > > > Error:
> > > > Access to performance monitoring and observability operations is limited.
> > > > Enforced MAC policy settings (SELinux) can limit access to performance
> > > > monitoring and observability operations. Inspect system audit records for
> > > > more perf_event access control information and adjusting the policy.
> > > > Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open
> > > > access to performance monitoring and observability operations for processes
> > > > without CAP_PERFMON, CAP_SYS_PTRACE or CAP_SYS_ADMIN Linux capability.
> > > > More information can be found at 'Perf events and tool security' document:
> > > > https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html
> > > > perf_event_paranoid setting is 2:
> > > > -1: Allow use of (almost) all events by all users
> > > > Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
> > > > >= 0: Disallow raw and ftrace function tracepoint access
> > > > >= 1: Disallow CPU event access
> > > > >= 2: Disallow kernel profiling
> > > > To make the adjusted perf_event_paranoid setting permanent preserve it
> > > > in /etc/sysctl.conf (e.g. kernel.perf_event_paranoid = <setting>)
> > > Hmm, I would rather like pointing manpages...
> > Man pages are long, if you quote the relevant part of it when the
> > problem takes place, IMHO it helps the user.
> OK, but please also update man pages (*), which can provide a summarized information
> for users if they noticed that. And for each place, I will add some messages
> for letting them know.
Sure, its not one or the other, its both, i.e. man pages are interesting
as the standard reference for a command, while making tools provide
information about a specific problem with actionable advice on how to
fix the problem at hand is important as well.
> (*) https://lore.kernel.org/lkml/162204068898.388434.16842705842611255787.stgit@devnote2/
I saw your patch to the man page and asked Ravi for an Ack/Reviewed-by,
Thanks for all your continued work on this! :-)
- Arnaldo
next prev parent reply other threads:[~2021-06-02 13:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-25 4:37 [PATCH] perf probe: Provide more detail with relocation warning Ravi Bangoria
2021-05-25 12:48 ` Masami Hiramatsu
2021-05-26 4:53 ` Ravi Bangoria
2021-05-26 6:33 ` Masami Hiramatsu
2021-05-26 12:56 ` Arnaldo Carvalho de Melo
2021-05-26 14:20 ` Masami Hiramatsu
2021-06-02 11:52 ` Arnaldo Carvalho de Melo
2021-06-02 12:12 ` Masami Hiramatsu
2021-06-02 13:15 ` Arnaldo Carvalho de Melo [this message]
2021-05-26 9:01 ` [PATCH] tools/perf: doc: Add permission and sysctl notice Masami Hiramatsu
2021-05-26 9:50 ` Ravi Bangoria
2021-05-26 13:16 ` Masami Hiramatsu
2021-05-26 14:51 ` [PATCH v2] " Masami Hiramatsu
2021-06-02 11:53 ` Arnaldo Carvalho de Melo
2021-06-02 13:51 ` Ravi Bangoria
2021-06-04 13:25 ` Arnaldo Carvalho de Melo
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