[PATCHv2 bpf-next 22/23] selftests/bpf: Add tracing multi attach benchmark test

[Jiri Olsa <jolsa@kernel.org>]

Adding benchmark test that attaches to (almost) all allowed tracing
functions and display attach/detach times.

  # ./test_progs -t tracing_multi_bench_attach -v
  bpf_testmod.ko is already unloaded.
  Loading bpf_testmod.ko...
  Successfully loaded bpf_testmod.ko.
  serial_test_tracing_multi_bench_attach:PASS:btf__load_vmlinux_btf 0 nsec
  serial_test_tracing_multi_bench_attach:PASS:tracing_multi_bench__open_and_load 0 nsec
  serial_test_tracing_multi_bench_attach:PASS:get_syms 0 nsec
  serial_test_tracing_multi_bench_attach:PASS:bpf_program__attach_tracing_multi 0 nsec
  serial_test_tracing_multi_bench_attach: found 51186 functions
  serial_test_tracing_multi_bench_attach: attached in   1.295s
  serial_test_tracing_multi_bench_attach: detached in   0.243s
  #507     tracing_multi_bench_attach:OK
  Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
  Successfully unloaded bpf_testmod.ko.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../selftests/bpf/prog_tests/tracing_multi.c  | 178 ++++++++++++++++++
 .../selftests/bpf/progs/tracing_multi_bench.c |  13 ++
 2 files changed, 191 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_multi_bench.c

diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_multi.c b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
index d64d90f4e086..585d6b646d20 100644
--- a/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_multi.c
@@ -9,6 +9,7 @@
 #include "tracing_multi_intersect.skel.h"
 #include "tracing_multi_session.skel.h"
 #include "tracing_multi_fail.skel.h"
+#include "tracing_multi_bench.skel.h"
 #include "trace_helpers.h"
 
 static __u64 bpf_fentry_test_cookies[] = {
@@ -543,6 +544,183 @@ static void test_attach_api_fails(void)
 	tracing_multi_fail__destroy(skel);
 }
 
+/*
+ * Skip several kernel symbols that might not be safe or could cause delays.
+ */
+static bool skip_symbol(char *name)
+{
+	if (!strcmp(name, "arch_cpu_idle"))
+		return true;
+	if (!strcmp(name, "default_idle"))
+		return true;
+	if (!strncmp(name, "rcu_", 4))
+		return true;
+	if (!strcmp(name, "bpf_dispatcher_xdp_func"))
+		return true;
+	if (strstr(name, "rcu"))
+		return true;
+	if (strstr(name, "trace"))
+		return true;
+	if (strstr(name, "irq"))
+		return true;
+	if (strstr(name, "bpf_lsm_"))
+		return true;
+	if (!strcmp(name, "migrate_enable"))
+		return true;
+	if (!strcmp(name, "migrate_disable"))
+		return true;
+	if (!strcmp(name, "preempt_count_sub"))
+		return true;
+	if (!strcmp(name, "preempt_count_add"))
+		return true;
+	return false;
+}
+
+#define MAX_BPF_FUNC_ARGS 12
+
+static bool btf_type_is_modifier(const struct btf_type *t)
+{
+	switch (BTF_INFO_KIND(t->info)) {
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_TYPE_TAG:
+		return true;
+	}
+	return false;
+}
+
+static bool is_allowed_func(const struct btf *btf, const struct btf_type *t)
+{
+	const struct btf_type *proto;
+	const struct btf_param *args;
+	__u32 i, nargs;
+	__s64 ret;
+
+	proto = btf_type_by_id(btf, t->type);
+	if (BTF_INFO_KIND(proto->info) != BTF_KIND_FUNC_PROTO)
+		return false;
+
+	args = (const struct btf_param *)(proto + 1);
+	nargs = btf_vlen(proto);
+	if (nargs > MAX_BPF_FUNC_ARGS)
+		return false;
+
+	t = btf__type_by_id(btf, proto->type);
+	while (t && btf_type_is_modifier(t))
+		t = btf__type_by_id(btf, t->type);
+
+	if (btf_is_struct(t) || btf_is_union(t))
+		return false;
+
+	for (i = 0; i < nargs; i++) {
+		/* No support for variable args */
+		if (i == nargs - 1 && args[i].type == 0)
+			return false;
+
+		/* No support of struct argument size greater than 16 bytes */
+		ret = btf__resolve_size(btf, args[i].type);
+		if (ret < 0 || ret > 16)
+			return false;
+	}
+
+	return true;
+}
+
+void serial_test_tracing_multi_bench_attach(void)
+{
+	LIBBPF_OPTS(bpf_tracing_multi_opts, opts);
+	struct tracing_multi_bench *skel = NULL;
+	long attach_start_ns, attach_end_ns;
+	long detach_start_ns, detach_end_ns;
+	double attach_delta, detach_delta;
+	struct bpf_link *link = NULL;
+	size_t i, cap = 0, cnt = 0;
+	struct ksyms *ksyms = NULL;
+	void *root = NULL;
+	__u32 *ids = NULL;
+	__u32 nr, type_id;
+	struct btf *btf;
+	int err;
+
+#ifndef __x86_64__
+	test__skip();
+	return;
+#endif
+
+	btf = btf__load_vmlinux_btf();
+	if (!ASSERT_OK_PTR(btf, "btf__load_vmlinux_btf"))
+		return;
+
+	skel = tracing_multi_bench__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "tracing_multi_bench__open_and_load"))
+		goto cleanup;
+
+	if (!ASSERT_OK(bpf_get_ksyms(&ksyms, true), "get_syms"))
+		goto cleanup;
+
+	for (i = 0; i < ksyms->filtered_cnt; i++) {
+		if (skip_symbol(ksyms->filtered_syms[i]))
+			continue;
+		tsearch(&ksyms->filtered_syms[i], &root, compare);
+	}
+
+	nr = btf__type_cnt(btf);
+	for (type_id = 1; type_id < nr; type_id++) {
+		const struct btf_type *type;
+		const char *str;
+
+		type = btf__type_by_id(btf, type_id);
+		if (!type)
+			break;
+
+		if (BTF_INFO_KIND(type->info) != BTF_KIND_FUNC)
+			continue;
+
+		str = btf__name_by_offset(btf, type->name_off);
+		if (!str)
+			break;
+
+		if (!tfind(&str, &root, compare))
+			continue;
+
+		if (!is_allowed_func(btf, type))
+			continue;
+
+		err = libbpf_ensure_mem((void **) &ids, &cap, sizeof(*ids), cnt + 1);
+		if (err)
+			break;
+
+		ids[cnt++] = type_id;
+	}
+
+	opts.ids = ids;
+	opts.cnt = cnt;
+
+	attach_start_ns = get_time_ns();
+	link = bpf_program__attach_tracing_multi(skel->progs.bench, NULL, &opts);
+	attach_end_ns = get_time_ns();
+
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_tracing_multi"))
+		goto cleanup;
+
+	detach_start_ns = get_time_ns();
+	bpf_link__destroy(link);
+	detach_end_ns = get_time_ns();
+
+	attach_delta = (attach_end_ns - attach_start_ns) / 1000000000.0;
+	detach_delta = (detach_end_ns - detach_start_ns) / 1000000000.0;
+
+	printf("%s: found %lu functions\n", __func__, cnt);
+	printf("%s: attached in %7.3lfs\n", __func__, attach_delta);
+	printf("%s: detached in %7.3lfs\n", __func__, detach_delta);
+
+cleanup:
+	tracing_multi_bench__destroy(skel);
+	free_kallsyms_local(ksyms);
+}
+
 void test_tracing_multi_test(void)
 {
 #ifndef __x86_64__
diff --git a/tools/testing/selftests/bpf/progs/tracing_multi_bench.c b/tools/testing/selftests/bpf/progs/tracing_multi_bench.c
new file mode 100644
index 000000000000..067ba668489b
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tracing_multi_bench.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdbool.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("fentry.multi")
+int BPF_PROG(bench)
+{
+	return 0;
+}
-- 
2.53.0