selftests/bpf: Add attach bench test

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

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20220510122616.2652285-6-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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 c56db65..816eace 100644 (file)
--- 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 +304,144 @@ cleanup:
        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;
+               /*
+                * We attach to almost all kernel functions and some of them
+                * will cause 'suspicious RCU usage' when fprobe is attached
+                * to them. Filter out the current culprits - arch_cpu_idle
+                * and rcu_* functions.
+                */
+               if (!strcmp(name, "arch_cpu_idle"))
+                       continue;
+               if (!strncmp(name, "rcu_", 4))
+                       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 +461,6 @@ 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 (file)
index 0000000..e76e499
--- /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;
+}