selftests/bpf: Add a kprobe_multi subtest to use addrs instead of syms

Get addrs directly from available_filter_functions_addrs and
send to the kernel during kprobe_multi_attach. This avoids
consultation of /proc/kallsyms. But available_filter_functions_addrs
is introduced in 6.5, i.e., it is introduced recently,
so I skip the test if the kernel does not support it.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041523.1200301-1-yonghong.song@linux.dev
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 3b90591643607a02c92c13bb8b8d055794f40ca8..51628455b6f528cc2330956a7712ebe4c68ac4e7 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -477,6 +477,69 @@ error:
        return err;
 }
 
+static int get_addrs(unsigned long **addrsp, size_t *cntp, bool kernel)
+{
+       unsigned long *addr, *addrs, *tmp_addrs;
+       int err = 0, max_cnt, inc_cnt;
+       char *name = NULL;
+       size_t cnt = 0;
+       char buf[256];
+       FILE *f;
+
+       if (access("/sys/kernel/tracing/trace", F_OK) == 0)
+               f = fopen("/sys/kernel/tracing/available_filter_functions_addrs", "r");
+       else
+               f = fopen("/sys/kernel/debug/tracing/available_filter_functions_addrs", "r");
+
+       if (!f)
+               return -ENOENT;
+
+       /* In my local setup, the number of entries is 50k+ so Let us initially
+        * allocate space to hold 64k entries. If 64k is not enough, incrementally
+        * increase 1k each time.
+        */
+       max_cnt = 65536;
+       inc_cnt = 1024;
+       addrs = malloc(max_cnt * sizeof(long));
+       if (addrs == NULL) {
+               err = -ENOMEM;
+               goto error;
+       }
+
+       while (fgets(buf, sizeof(buf), f)) {
+               if (is_invalid_entry(buf, kernel))
+                       continue;
+
+               free(name);
+               if (sscanf(buf, "%p %ms$*[^\n]\n", &addr, &name) != 2)
+                       continue;
+               if (skip_entry(name))
+                       continue;
+
+               if (cnt == max_cnt) {
+                       max_cnt += inc_cnt;
+                       tmp_addrs = realloc(addrs, max_cnt);
+                       if (!tmp_addrs) {
+                               err = -ENOMEM;
+                               goto error;
+                       }
+                       addrs = tmp_addrs;
+               }
+
+               addrs[cnt++] = (unsigned long)addr;
+       }
+
+       *addrsp = addrs;
+       *cntp = cnt;
+
+error:
+       free(name);
+       fclose(f);
+       if (err)
+               free(addrs);
+       return err;
+}
+
 static void do_bench_test(struct kprobe_multi_empty *skel, struct bpf_kprobe_multi_opts *opts)
 {
        long attach_start_ns, attach_end_ns;
@@ -529,6 +592,37 @@ cleanup:
                free(syms);
 }
 
+static void test_kprobe_multi_bench_attach_addr(bool kernel)
+{
+       LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
+       struct kprobe_multi_empty *skel = NULL;
+       unsigned long *addrs = NULL;
+       size_t cnt = 0;
+       int err;
+
+       err = get_addrs(&addrs, &cnt, kernel);
+       if (err == -ENOENT) {
+               test__skip();
+               return;
+       }
+
+       if (!ASSERT_OK(err, "get_addrs"))
+               return;
+
+       skel = kprobe_multi_empty__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "kprobe_multi_empty__open_and_load"))
+               goto cleanup;
+
+       opts.addrs = addrs;
+       opts.cnt = cnt;
+
+       do_bench_test(skel, &opts);
+
+cleanup:
+       kprobe_multi_empty__destroy(skel);
+       free(addrs);
+}
+
 static void test_attach_override(void)
 {
        struct kprobe_multi_override *skel = NULL;
@@ -569,6 +663,10 @@ void serial_test_kprobe_multi_bench_attach(void)
                test_kprobe_multi_bench_attach(true);
        if (test__start_subtest("modules"))
                test_kprobe_multi_bench_attach(false);
+       if (test__start_subtest("kernel"))
+               test_kprobe_multi_bench_attach_addr(true);
+       if (test__start_subtest("modules"))
+               test_kprobe_multi_bench_attach_addr(false);
 }
 
 void test_kprobe_multi_test(void)