The current kprobe_multi_bench_attach/kernel test
reads sym names from /sys/kernel/tracing/available_filter_functions.
Some names do not agree with the corresponding entries in /proc/kallsyms
since the corresponding /proc/kallsyms syms have suffix '.llvm.<hash>'.
Actually, if we pass symbol names in /proc/kallsyms,
kprobe_multi_attach will be okay.
This patch added a new subtest where addresses are retrieved from
/sys/kernel/tracing/available_filter_functions_addrs, and use the
address to consule /proc/kallsyms to get the function name.
Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx>
---
.../bpf/prog_tests/kprobe_multi_test.c | 139 ++++++++++++++++++
1 file changed, 139 insertions(+)
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 f6130f4f3d88..142309ced146 100644
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -438,6 +438,102 @@ static int get_syms(char ***symsp, size_t *cntp, bool kernel)
return err;
}
+static int get_syms_from_addr(char ***symsp, size_t *cntp)
+{
+ char *name = NULL, **syms = NULL;
+ size_t cap = 0, cnt = 0, i;
+ struct hashmap *map;
+ struct ksym *ks;
+ char buf[256];
+ FILE *f;
+ int err = 0;
+ void *addr;
+
+ if (!ASSERT_OK(load_kallsyms(), "load_kallsyms"))
+ return -EINVAL;
+ /*
+ * 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.
+ */
+
+ 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;
+
+ map = hashmap__new(symbol_hash, symbol_equal, NULL);
+ if (IS_ERR(map)) {
+ err = libbpf_get_error(map);
+ goto error;
+ }
+
+ while (fgets(buf, sizeof(buf), f)) {
+ if (strchr(buf, '['))
+ continue;
+
+ if (sscanf(buf, "%p$*[^\n]\n", &addr) != 1)
+ continue;
+
+ ks = ksym_search((long)addr);
+ if (!ks)
+ return -EINVAL;
+
+ name = ks->name;
+
+ /*
+ * 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
+ * default_idle and rcu_* functions.
+ */
+ if (!strcmp(name, "arch_cpu_idle"))
+ continue;
+ if (!strcmp(name, "default_idle"))
+ continue;
+ if (!strncmp(name, "rcu_", 4))
+ continue;
+ if (!strcmp(name, "bpf_dispatcher_xdp_func"))
+ continue;
+ if (!strncmp(name, "__ftrace_invalid_address__",
+ sizeof("__ftrace_invalid_address__") - 1))
+ continue;
+
+ err = hashmap__add(map, name, 0);
+ if (err == -EEXIST) {
+ err = 0;
+ continue;
+ }
+ if (err)
+ goto error;
+
+ err = libbpf_ensure_mem((void **) &syms, &cap,
+ sizeof(*syms), cnt + 1);
+ if (err)
+ goto error;
+
+ syms[cnt++] = name;
+ }
+
+ *symsp = syms;
+ *cntp = cnt;
+
+error:
+ fclose(f);
+ hashmap__free(map);
+ if (err) {
+ for (i = 0; i < cnt; i++)
+ free(syms[i]);
+ free(syms);
+ }
+ return err;
+}
+
static void test_kprobe_multi_bench_attach(bool kernel)
{
LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
@@ -521,6 +617,47 @@ static void test_attach_override(void)
kprobe_multi_override__destroy(skel);
}
+static void test_attach_kernel_addrs_to_sym(void)
+{
+ LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
+ struct kprobe_multi_empty *skel;
+ struct bpf_link *link;
+ char **syms = NULL;
+ size_t cnt = 0;
+ int i, err;
+
+ err = get_syms_from_addr(&syms, &cnt);
+ if (err == -ENOENT) {
+ test__skip();
+ return;
+ }
+ if (!ASSERT_OK(err, "get_syms_from_addr"))
+ 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;
+
+ link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_empty,
+ NULL, &opts);
+
+ if (!ASSERT_OK_PTR(link, "bpf_program__attach_kprobe_multi_opts"))
+ goto cleanup;
+
+ bpf_link__destroy(link);
+
+cleanup:
+ kprobe_multi_empty__destroy(skel);
+ if (syms) {
+ for (i = 0; i < cnt; i++)
+ free(syms[i]);
+ free(syms);
+ }
+}
+
void serial_test_kprobe_multi_bench_attach(void)
{
if (test__start_subtest("kernel"))
@@ -550,4 +687,6 @@ void test_kprobe_multi_test(void)
test_attach_api_fails();
if (test__start_subtest("attach_override"))
test_attach_override();
+ if (test__start_subtest("kernel_addrs_to_sym"))
+ test_attach_kernel_addrs_to_sym();
}
--
2.43.0
