[PATCHv3 bpf-next 5/5] selftests/bpf: Add attach bench test

Jiri Olsa
2022-04-27T21:05:11Z

Adding test that reads all functions from ftrace available_filter_functions
file and attach them all through kprobe_multi API.

It also prints stats info with -v option, like on my setup:

test_bench_attach: found 48712 functions
test_bench_attach: attached in 1.069s
test_bench_attach: detached in 0.373s

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
.../bpf/prog_tests/kprobe_multi_test.c | 133 ++++++++++++++++++
.../selftests/bpf/progs/kprobe_multi_empty.c | 12 ++
2 files changed, 145 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/kprobe_multi_empty.c

diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
index b9876b55fc0c..a0664c5c15ee 100644
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -2,6 +2,9 @@
#include <test_progs.h>
#include "kprobe_multi.skel.h"
#include "trace_helpers.h"
+#include "kprobe_multi_empty.skel.h"
+#include "bpf/libbpf_internal.h"
+#include "bpf/hashmap.h"

static void kprobe_multi_test_run(struct kprobe_multi *skel, bool test_return)
{
@@ -301,6 +304,134 @@ static void test_attach_api_fails(void)
kprobe_multi__destroy(skel);
}

+static inline __u64 get_time_ns(void)
+{
+ struct timespec t;
+
+ clock_gettime(CLOCK_MONOTONIC, &t);
+ return (__u64) t.tv_sec * 1000000000 + t.tv_nsec;
+}
+
+static size_t symbol_hash(const void *key, void *ctx __maybe_unused)
+{
+ return str_hash((const char *) key);
+}
+
+static bool symbol_equal(const void *key1, const void *key2, void *ctx __maybe_unused)
+{
+ return strcmp((const char *) key1, (const char *) key2) == 0;
+}
+
+static int get_syms(char ***symsp, size_t *cntp)
+{
+ size_t cap = 0, cnt = 0, i;
+ char *name, **syms = NULL;
+ struct hashmap *map;
+ char buf[256];
+ FILE *f;
+ int err;
+
+ /*
+ * The available_filter_functions contains many duplicates,
+ * but other than that all symbols are usable in kprobe multi
+ * interface.
+ * Filtering out duplicates by using hashmap__add, which won't
+ * add existing entry.
+ */
+ f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
+ if (!f)
+ return -EINVAL;
+
+ map = hashmap__new(symbol_hash, symbol_equal, NULL);
+ if (IS_ERR(map))
+ goto error;
+
+ while (fgets(buf, sizeof(buf), f)) {
+ /* skip modules */
+ if (strchr(buf, '['))
+ continue;
+ if (sscanf(buf, "%ms$*[^\n]\n", &name) != 1)
+ continue;
+ err = hashmap__add(map, name, NULL);
+ if (err) {
+ free(name);
+ if (err == -EEXIST)
+ continue;
+ goto error;
+ }
+ err = libbpf_ensure_mem((void **) &syms, &cap,
+ sizeof(*syms), cnt + 1);
+ if (err) {
+ free(name);
+ goto error;
+ }
+ syms[cnt] = name;
+ cnt++;
+ }
+
+ *symsp = syms;
+ *cntp = cnt;
+
+error:
+ fclose(f);
+ hashmap__free(map);
+ if (err) {
+ for (i = 0; i < cnt; i++)
+ free(syms[cnt]);
+ free(syms);
+ }
+ return err;
+}
+
+static void test_bench_attach(void)
+{
+ LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
+ struct kprobe_multi_empty *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;
+ char **syms = NULL;
+ size_t cnt, i;
+
+ if (!ASSERT_OK(get_syms(&syms, &cnt), "get_syms"))
+ return;
+
+ skel = kprobe_multi_empty__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "kprobe_multi_empty__open_and_load"))
+ goto cleanup;
+
+ opts.syms = (const char **) syms;
+ opts.cnt = cnt;
+
+ attach_start_ns = get_time_ns();
+ link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_empty,
+ NULL, &opts);
+ attach_end_ns = get_time_ns();
+
+ if (!ASSERT_OK_PTR(link, "bpf_program__attach_kprobe_multi_opts"))
+ 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:
+ kprobe_multi_empty__destroy(skel);
+ if (syms) {
+ for (i = 0; i < cnt; i++)
+ free(syms[i]);
+ free(syms);
+ }
+}
+
void test_kprobe_multi_test(void)
{
if (!ASSERT_OK(load_kallsyms(), "load_kallsyms"))
@@ -320,4 +451,6 @@ void test_kprobe_multi_test(void)
test_attach_api_syms();
if (test__start_subtest("attach_api_fails"))
test_attach_api_fails();
+ if (test__start_subtest("bench_attach"))
+ test_bench_attach();
}
diff --git a/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c b/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c
new file mode 100644
index 000000000000..e76e499aca39
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("kprobe.multi/")
+int test_kprobe_empty(struct pt_regs *ctx)
+{
+ return 0;
+}
--
2.35.1