From 525615ef6df476d5fe277d311c645b4c179d56db Mon Sep 17 00:00:00 2001
From: Ian Rogers <irogers@google.com>
Date: Thu, 7 Mar 2024 16:19:10 -0800
Subject: [PATCH] perf list: Add tracepoint encoding to detailed output

The tracepoint id holds the config value and is probed in determining
what an event is. Add reading of the id so that we can display the
event encoding as:

  $ perf list --details
  ...
    alarmtimer:alarmtimer_cancel                       [Tracepoint event]
          tracepoint/config=0x18c/
  ...

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Kan Liang <kan.liang@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20240308001915.4060155-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/print-events.c | 37 ++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/tools/perf/util/print-events.c b/tools/perf/util/print-events.c
index 7b54e9385442..e0d2b49bab66 100644
--- a/tools/perf/util/print-events.c
+++ b/tools/perf/util/print-events.c
@@ -9,6 +9,7 @@
 #include <unistd.h>
 
 #include <api/fs/tracing_path.h>
+#include <api/io.h>
 #include <linux/stddef.h>
 #include <linux/perf_event.h>
 #include <linux/zalloc.h>
@@ -92,34 +93,48 @@ void print_tracepoint_events(const struct print_callbacks *print_cb __maybe_unus
 
 		evt_items = scandirat(events_fd, sys_dirent->d_name, &evt_namelist, NULL, alphasort);
 		for (int j = 0; j < evt_items; j++) {
+			/*
+			 * Buffer sized at twice the max filename length + 1
+			 * separator + 1 \0 terminator.
+			 */
+			char buf[NAME_MAX * 2 + 2];
+			/* 16 possible hex digits and 22 other characters and \0. */
+			char encoding[16 + 22];
 			struct dirent *evt_dirent = evt_namelist[j];
-			char evt_path[MAXPATHLEN];
-			int evt_fd;
+			struct io id;
+			__u64 config;
 
 			if (evt_dirent->d_type != DT_DIR ||
 			    !strcmp(evt_dirent->d_name, ".") ||
 			    !strcmp(evt_dirent->d_name, ".."))
 				goto next_evt;
 
-			snprintf(evt_path, sizeof(evt_path), "%s/id", evt_dirent->d_name);
-			evt_fd = openat(dir_fd, evt_path, O_RDONLY);
-			if (evt_fd < 0)
-				goto next_evt;
-			close(evt_fd);
+			snprintf(buf, sizeof(buf), "%s/id", evt_dirent->d_name);
+			io__init(&id, openat(dir_fd, buf, O_RDONLY), buf, sizeof(buf));
 
-			snprintf(evt_path, MAXPATHLEN, "%s:%s",
+			if (id.fd < 0)
+				goto next_evt;
+
+			if (io__get_dec(&id, &config) < 0) {
+				close(id.fd);
+				goto next_evt;
+			}
+			close(id.fd);
+
+			snprintf(buf, sizeof(buf), "%s:%s",
 				 sys_dirent->d_name, evt_dirent->d_name);
+			snprintf(encoding, sizeof(encoding), "tracepoint/config=0x%llx/", config);
 			print_cb->print_event(print_state,
 					/*topic=*/NULL,
-					/*pmu_name=*/NULL,
-					evt_path,
+					/*pmu_name=*/NULL, /* really "tracepoint" */
+					/*event_name=*/buf,
 					/*event_alias=*/NULL,
 					/*scale_unit=*/NULL,
 					/*deprecated=*/false,
 					"Tracepoint event",
 					/*desc=*/NULL,
 					/*long_desc=*/NULL,
-					/*encoding_desc=*/NULL);
+					encoding);
 next_evt:
 			free(evt_namelist[j]);
 		}