[PATCH 1/6] perf bpf-filter: Make filters map a single entry hashmap

[Namhyung Kim]

And the value is now an array.  This is to support multiple filter
entries in the map later.

No functional changes intended.

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/util/bpf-filter.c                 | 81 ++++++++++++++------
 tools/perf/util/bpf_skel/sample-filter.h     |  3 +-
 tools/perf/util/bpf_skel/sample_filter.bpf.c | 37 +++++----
 3 files changed, 78 insertions(+), 43 deletions(-)

diff --git a/tools/perf/util/bpf-filter.c b/tools/perf/util/bpf-filter.c
index b51544996046..12e9c7dbb4dd 100644
--- a/tools/perf/util/bpf-filter.c
+++ b/tools/perf/util/bpf-filter.c
@@ -87,71 +87,102 @@ static int check_sample_flags(struct evsel *evsel, struct perf_bpf_filter_expr *
 
 int perf_bpf_filter__prepare(struct evsel *evsel)
 {
-	int i, x, y, fd;
+	int i, x, y, fd, ret;
 	struct sample_filter_bpf *skel;
 	struct bpf_program *prog;
 	struct bpf_link *link;
 	struct perf_bpf_filter_expr *expr;
+	struct perf_bpf_filter_entry *entry;
+
+	entry = calloc(MAX_FILTERS, sizeof(*entry));
+	if (entry == NULL)
+		return -1;
 
 	skel = sample_filter_bpf__open_and_load();
 	if (!skel) {
 		pr_err("Failed to load perf sample-filter BPF skeleton\n");
-		return -1;
+		ret = -EPERM;
+		goto err;
 	}
 
 	i = 0;
 	fd = bpf_map__fd(skel->maps.filters);
 	list_for_each_entry(expr, &evsel->bpf_filters, list) {
-		struct perf_bpf_filter_entry entry = {
-			.op = expr->op,
-			.part = expr->part,
-			.flags = expr->sample_flags,
-			.value = expr->val,
-		};
+		if (check_sample_flags(evsel, expr) < 0) {
+			ret = -EINVAL;
+			goto err;
+		}
 
-		if (check_sample_flags(evsel, expr) < 0)
-			return -1;
+		if (i == MAX_FILTERS) {
+			ret = -E2BIG;
+			goto err;
+		}
 
-		bpf_map_update_elem(fd, &i, &entry, BPF_ANY);
+		entry[i].op = expr->op;
+		entry[i].part = expr->part;
+		entry[i].flags = expr->sample_flags;
+		entry[i].value = expr->val;
 		i++;
 
 		if (expr->op == PBF_OP_GROUP_BEGIN) {
 			struct perf_bpf_filter_expr *group;
 
 			list_for_each_entry(group, &expr->groups, list) {
-				struct perf_bpf_filter_entry group_entry = {
-					.op = group->op,
-					.part = group->part,
-					.flags = group->sample_flags,
-					.value = group->val,
-				};
-				bpf_map_update_elem(fd, &i, &group_entry, BPF_ANY);
+				if (i == MAX_FILTERS) {
+					ret = -E2BIG;
+					goto err;
+				}
+
+				entry[i].op = group->op;
+				entry[i].part = group->part;
+				entry[i].flags = group->sample_flags;
+				entry[i].value = group->val;
 				i++;
 			}
 
-			memset(&entry, 0, sizeof(entry));
-			entry.op = PBF_OP_GROUP_END;
-			bpf_map_update_elem(fd, &i, &entry, BPF_ANY);
+			if (i == MAX_FILTERS) {
+				ret = -E2BIG;
+				goto err;
+			}
+
+			entry[i].op = PBF_OP_GROUP_END;
 			i++;
 		}
 	}
 
-	if (i > MAX_FILTERS) {
-		pr_err("Too many filters: %d (max = %d)\n", i, MAX_FILTERS);
-		return -1;
+	if (i < MAX_FILTERS) {
+		/* to terminate the loop early */
+		entry[i].op = PBF_OP_DONE;
+		i++;
+	}
+
+	/* The filters map has only one entry for now */
+	i = 0;
+	if (bpf_map_update_elem(fd, &i, entry, BPF_ANY) < 0) {
+		ret = -errno;
+		pr_err("Failed to update the filter map\n");
+		goto err;
 	}
+
 	prog = skel->progs.perf_sample_filter;
 	for (x = 0; x < xyarray__max_x(evsel->core.fd); x++) {
 		for (y = 0; y < xyarray__max_y(evsel->core.fd); y++) {
 			link = bpf_program__attach_perf_event(prog, FD(evsel, x, y));
 			if (IS_ERR(link)) {
 				pr_err("Failed to attach perf sample-filter program\n");
-				return PTR_ERR(link);
+				ret = PTR_ERR(link);
+				goto err;
 			}
 		}
 	}
+	free(entry);
 	evsel->bpf_skel = skel;
 	return 0;
+
+err:
+	free(entry);
+	sample_filter_bpf__destroy(skel);
+	return ret;
 }
 
 int perf_bpf_filter__destroy(struct evsel *evsel)
diff --git a/tools/perf/util/bpf_skel/sample-filter.h b/tools/perf/util/bpf_skel/sample-filter.h
index 2e96e1ab084a..cf18f570eef4 100644
--- a/tools/perf/util/bpf_skel/sample-filter.h
+++ b/tools/perf/util/bpf_skel/sample-filter.h
@@ -14,6 +14,7 @@ enum perf_bpf_filter_op {
 	PBF_OP_AND,
 	PBF_OP_GROUP_BEGIN,
 	PBF_OP_GROUP_END,
+	PBF_OP_DONE,
 };
 
 /* BPF map entry for filtering */
@@ -24,4 +25,4 @@ struct perf_bpf_filter_entry {
 	__u64 value;
 };
 
-#endif /* PERF_UTIL_BPF_SKEL_SAMPLE_FILTER_H */
\ No newline at end of file
+#endif /* PERF_UTIL_BPF_SKEL_SAMPLE_FILTER_H */
diff --git a/tools/perf/util/bpf_skel/sample_filter.bpf.c b/tools/perf/util/bpf_skel/sample_filter.bpf.c
index fb94f5280626..5f17cd6458b7 100644
--- a/tools/perf/util/bpf_skel/sample_filter.bpf.c
+++ b/tools/perf/util/bpf_skel/sample_filter.bpf.c
@@ -9,10 +9,10 @@
 
 /* BPF map that will be filled by user space */
 struct filters {
-	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(type, BPF_MAP_TYPE_HASH);
 	__type(key, int);
-	__type(value, struct perf_bpf_filter_entry);
-	__uint(max_entries, MAX_FILTERS);
+	__type(value, struct perf_bpf_filter_entry[MAX_FILTERS]);
+	__uint(max_entries, 1);
 } filters SEC(".maps");
 
 int dropped;
@@ -144,35 +144,35 @@ int perf_sample_filter(void *ctx)
 
 	kctx = bpf_cast_to_kern_ctx(ctx);
 
-	for (i = 0; i < MAX_FILTERS; i++) {
-		int key = i; /* needed for verifier :( */
+	i = 0;
+	entry = bpf_map_lookup_elem(&filters, &i);
+	if (entry == NULL)
+		goto drop;
 
-		entry = bpf_map_lookup_elem(&filters, &key);
-		if (entry == NULL)
-			break;
-		sample_data = perf_get_sample(kctx, entry);
+	for (i = 0; i < MAX_FILTERS; i++) {
+		sample_data = perf_get_sample(kctx, &entry[i]);
 
-		switch (entry->op) {
+		switch (entry[i].op) {
 		case PBF_OP_EQ:
-			CHECK_RESULT(sample_data, ==, entry->value)
+			CHECK_RESULT(sample_data, ==, entry[i].value)
 			break;
 		case PBF_OP_NEQ:
-			CHECK_RESULT(sample_data, !=, entry->value)
+			CHECK_RESULT(sample_data, !=, entry[i].value)
 			break;
 		case PBF_OP_GT:
-			CHECK_RESULT(sample_data, >, entry->value)
+			CHECK_RESULT(sample_data, >, entry[i].value)
 			break;
 		case PBF_OP_GE:
-			CHECK_RESULT(sample_data, >=, entry->value)
+			CHECK_RESULT(sample_data, >=, entry[i].value)
 			break;
 		case PBF_OP_LT:
-			CHECK_RESULT(sample_data, <, entry->value)
+			CHECK_RESULT(sample_data, <, entry[i].value)
 			break;
 		case PBF_OP_LE:
-			CHECK_RESULT(sample_data, <=, entry->value)
+			CHECK_RESULT(sample_data, <=, entry[i].value)
 			break;
 		case PBF_OP_AND:
-			CHECK_RESULT(sample_data, &, entry->value)
+			CHECK_RESULT(sample_data, &, entry[i].value)
 			break;
 		case PBF_OP_GROUP_BEGIN:
 			in_group = 1;
@@ -183,6 +183,9 @@ int perf_sample_filter(void *ctx)
 				goto drop;
 			in_group = 0;
 			break;
+		case PBF_OP_DONE:
+			/* no failures so far, accept it */
+			return 1;
 		}
 	}
 	/* generate sample data */
-- 
2.45.1.288.g0e0cd299f1-goog