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

From: Adrian Hunter
Date: Thu May 28 2020 - 08:09:42 EST


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@xxxxxxxxx>
---
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