perf script: Add option to list dlfilters

Add option --list-dlfilters to list dlfilters in the current directory or
the exec-path e.g. ~/libexec/perf-core/dlfilters. Use with option -v (must
come before option --list-dlfilters) to show long descriptions.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210627131818.810-4-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf-dlfilter.txt b/tools/perf/Documentation/perf-dlfilter.txt
index aef1c32babd1..8bc219f3eb83 100644
--- a/tools/perf/Documentation/perf-dlfilter.txt
+++ b/tools/perf/Documentation/perf-dlfilter.txt
@@ -37,6 +37,7 @@ int start(void **data, void *ctx);
 int stop(void *data, void *ctx);
 int filter_event(void *data, const struct perf_dlfilter_sample *sample, void *ctx);
 int filter_event_early(void *data, const struct perf_dlfilter_sample *sample, void *ctx);
+const char *filter_description(const char **long_description);
 ----
 
 If implemented, 'start' will be called at the beginning, before any
@@ -59,6 +60,9 @@ error code. 'data' is set by 'start'. 'ctx' is needed for calls to
 'filter_event_early' is the same as 'filter_event' except it is called before
 internal filtering.
 
+If implemented, 'filter_description' should return a one-line description
+of the filter, and optionally a longer description.
+
 The perf_dlfilter_sample structure
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~