linux-kernel - [PATCH 2/2] perf intel-pt: Refine kernel decoding only warning message

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Date:   Thu, 28 May 2020 15:08:59 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
        linux-kernel@...r.kernel.org,
        Mathieu Poirier <mathieu.poirier@...aro.org>
Subject: [PATCH 2/2] perf intel-pt: Refine kernel decoding only warning message

Stop the message displaying when user space is not being traced.

Example:

  Prerequisites:

    sudo setcap "cap_sys_rawio,cap_sys_admin,cap_sys_ptrace,cap_syslog,cap_ipc_lock=ep" ~/bin/perf
    sudo chmod +r /proc/kcore

  Before:

    $ perf record --no-switch-events --kcore -a -e intel_pt//k -- sleep 0.001
    Warning:
    Intel Processor Trace decoding will not be possible except for kernel tracing!
    [ perf record: Woken up 1 times to write data ]
    [ perf record: Captured and wrote 0.838 MB perf.data ]

  After:

    $ perf record --no-switch-events --kcore -a -e intel_pt//k -- sleep 0.001
    [ perf record: Woken up 1 times to write data ]
    [ perf record: Captured and wrote 1.068 MB perf.data ]

    $ sudo chmod go-r /proc/kcore
    $ sudo setcap -r ~/bin/perf

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/arch/x86/util/intel-pt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
index 3fc547769707..9fb137282dc8 100644
--- a/tools/perf/arch/x86/util/intel-pt.c
+++ b/tools/perf/arch/x86/util/intel-pt.c
@@ -879,7 +879,8 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
 	 * per-cpu with no sched_switch (except workload-only).
 	 */
 	if (!ptr->have_sched_switch && !perf_cpu_map__empty(cpus) &&
-	    !target__none(&opts->target))
+	    !target__none(&opts->target) &&
+	    !intel_pt_evsel->core.attr.exclude_user)
 		ui__warning("Intel Processor Trace decoding will not be possible except for kernel tracing!\n");
 
 	return 0;
-- 
2.17.1