perf bpf filter: Show warning for missing sample flags

For a BPF filter to work properly, users need to provide appropriate
options to enable the sample types.  Otherwise the BPF program would
see an invalid value (i.e. always 0) and filter won't work well.

Show a warning message if sample types are missing like below.

  $ sudo ./perf record -e cycles --filter 'addr < 100' true
  Error: cycles event does not have PERF_SAMPLE_ADDR
   Hint: please add -d option to perf record.
  failed to set filter "BPF" on event cycles with 22 (Invalid argument)

Signed-off-by: Namhyung Kim <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Hao Luo <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ravi Bangoria <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/perf/builtin-record.c

@@ -1353,7 +1353,7 @@ static int record__open(struct record *rec)
 
 	if (evlist__apply_filters(evlist, &pos)) {
 		pr_err("failed to set filter \"%s\" on event %s with %d (%s)\n",
-			pos->filter, evsel__name(pos), errno,
+			pos->filter ?: "BPF", evsel__name(pos), errno,
 			str_error_r(errno, msg, sizeof(msg)));
 		rc = -1;
 		goto out;

tools/perf/util/bpf-filter.c

@@ -17,6 +17,64 @@
 
 #define FD(e, x, y) (*(int *)xyarray__entry(e->core.fd, x, y))
 
+#define __PERF_SAMPLE_TYPE(st, opt)	{ st, #st, opt }
+#define PERF_SAMPLE_TYPE(_st, opt)	__PERF_SAMPLE_TYPE(PERF_SAMPLE_##_st, opt)
+
+static const struct perf_sample_info {
+	u64 type;
+	const char *name;
+	const char *option;
+} sample_table[] = {
+	/* default sample flags */
+	PERF_SAMPLE_TYPE(IP, NULL),
+	PERF_SAMPLE_TYPE(TID, NULL),
+	PERF_SAMPLE_TYPE(PERIOD, NULL),
+	/* flags mostly set by default, but still have options */
+	PERF_SAMPLE_TYPE(ID, "--sample-identifier"),
+	PERF_SAMPLE_TYPE(CPU, "--sample-cpu"),
+	PERF_SAMPLE_TYPE(TIME, "-T"),
+	/* optional sample flags */
+	PERF_SAMPLE_TYPE(ADDR, "-d"),
+	PERF_SAMPLE_TYPE(DATA_SRC, "-d"),
+	PERF_SAMPLE_TYPE(PHYS_ADDR, "--phys-data"),
+	PERF_SAMPLE_TYPE(WEIGHT, "-W"),
+	PERF_SAMPLE_TYPE(WEIGHT_STRUCT, "-W"),
+	PERF_SAMPLE_TYPE(TRANSACTION, "--transaction"),
+	PERF_SAMPLE_TYPE(CODE_PAGE_SIZE, "--code-page-size"),
+	PERF_SAMPLE_TYPE(DATA_PAGE_SIZE, "--data-page-size"),
+};
+
+static const struct perf_sample_info *get_sample_info(u64 flags)
+{
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(sample_table); i++) {
+		if (sample_table[i].type == flags)
+			return &sample_table[i];
+	}
+	return NULL;
+}
+
+static int check_sample_flags(struct evsel *evsel, struct perf_bpf_filter_expr *expr)
+{
+	const struct perf_sample_info *info;
+
+	if (evsel->core.attr.sample_type & expr->sample_flags)
+		return 0;
+
+	info = get_sample_info(expr->sample_flags);
+	if (info == NULL) {
+		pr_err("Error: %s event does not have sample flags %lx\n",
+		       evsel__name(evsel), expr->sample_flags);
+		return -1;
+	}
+
+	pr_err("Error: %s event does not have %s\n", evsel__name(evsel), info->name);
+	if (info->option)
+		pr_err(" Hint: please add %s option to perf record\n", info->option);
+	return -1;
+}
+
 int perf_bpf_filter__prepare(struct evsel *evsel)
 {
 	int i, x, y, fd;
@@ -40,6 +98,10 @@ int perf_bpf_filter__prepare(struct evsel *evsel)
 			.flags = expr->sample_flags,
 			.value = expr->val,
 		};
+
+		if (check_sample_flags(evsel, expr) < 0)
+			return -1;
+
 		bpf_map_update_elem(fd, &i, &entry, BPF_ANY);
 		i++;