linux-kernel - Re: [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability

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Message-ID: <20200407143551.GF11186@kernel.org>
Date:   Tue, 7 Apr 2020 11:35:51 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        James Morris <jmorris@...ei.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Serge Hallyn <serge@...lyn.com>, Jiri Olsa <jolsa@...hat.com>,
        Song Liu <songliubraving@...com>,
        Andi Kleen <ak@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>,
        Igor Lubashev <ilubashe@...mai.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "selinux@...r.kernel.org" <selinux@...r.kernel.org>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        linux-man@...r.kernel.org
Subject: Re: [PATCH v8 00/12] Introduce CAP_PERFMON to secure system
 performance monitoring and observability

Em Tue, Apr 07, 2020 at 11:30:14AM -0300, Arnaldo Carvalho de Melo escreveu:
> [perf@...e ~]$ type perf
> perf is hashed (/home/perf/bin/perf)
> [perf@...e ~]$ getcap /home/perf/bin/perf
> /home/perf/bin/perf = cap_sys_ptrace,cap_syslog,38+ep
> [perf@...e ~]$ groups
> perf perf_users
> [perf@...e ~]$ id
> uid=1002(perf) gid=1002(perf) groups=1002(perf),1003(perf_users) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> [perf@...e ~]$ perf top --stdio
> Error:
> Failed to mmap with 1 (Operation not permitted)
> [perf@...e ~]$ perf record -a
> ^C[ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 1.177 MB perf.data (1552 samples) ]
> 
> [perf@...e ~]$ perf evlist
> cycles:u
> [perf@...e ~]$

Humm, perf record falls back to cycles:u after initially trying cycles
(i.e. kernel and userspace), lemme see trying 'perf top -e cycles:u',
lemme test, humm not really:

[perf@...e ~]$ perf top --stdio -e cycles:u
Error:
Failed to mmap with 1 (Operation not permitted)
[perf@...e ~]$ perf record -e cycles:u -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 1.123 MB perf.data (132 samples) ]
[perf@...e ~]$

Back to debugging this.

- Arnaldo