There's limit of 40 programs tht can be attached
to trampoline for one function. Adding test that
tries to attach that many plus one extra that needs
to fail.
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
.../bpf/prog_tests/trampoline_count.c | 112 ++++++++++++++++++
.../bpf/progs/test_trampoline_count.c | 21 ++++
2 files changed, 133 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/trampoline_count.c
create mode 100644 tools/testing/selftests/bpf/progs/test_trampoline_count.c
diff --git a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
new file mode 100644
index 000000000000..1235f3d1cc50
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define _GNU_SOURCE
+#include <sched.h>
+#include <sys/prctl.h>
+#include <test_progs.h>
+
+#define MAX_TRAMP_PROGS 40
+
+struct inst {
+ struct bpf_object *obj;
+ struct bpf_link *link_fentry;
+ struct bpf_link *link_fexit;
+};
+
+static int test_task_rename(void)
+{
+ int fd, duration = 0, err;
+ char buf[] = "test_overhead";
+
+ fd = open("/proc/self/comm", O_WRONLY|O_TRUNC);
+ if (CHECK(fd < 0, "open /proc", "err %d", errno))
+ return -1;
+ err = write(fd, buf, sizeof(buf));
+ if (err < 0) {
+ CHECK(err < 0, "task rename", "err %d", errno);
+ close(fd);
+ return -1;
+ }
+ close(fd);
+ return 0;
+}
+
+static struct bpf_link *load(struct bpf_object *obj, const char *name)
+{
+ struct bpf_program *prog;
+ int duration = 0;
+
+ prog = bpf_object__find_program_by_title(obj, name);
+ if (CHECK(!prog, "find_probe", "prog '%s' not found\n", name))
+ return ERR_PTR(-EINVAL);
+ return bpf_program__attach_trace(prog);
+}
+
+void test_trampoline_count(void)
+{
+ const char *fentry_name = "fentry/__set_task_comm";
+ const char *fexit_name = "fexit/__set_task_comm";
+ const char *object = "test_trampoline_count.o";
+ struct inst inst[MAX_TRAMP_PROGS] = { 0 };
+ int err, i = 0, duration = 0;
+ struct bpf_object *obj;
+ struct bpf_link *link;
+ char comm[16] = {};
+
+ /* attach 'allowed' 40 trampoline programs */
+ for (i = 0; i < MAX_TRAMP_PROGS; i++) {
+ obj = bpf_object__open_file(object, NULL);
+ if (CHECK(IS_ERR(obj), "obj_open_file", "err %ld\n", PTR_ERR(obj)))
+ goto cleanup;
+
+ err = bpf_object__load(obj);
+ if (CHECK(err, "obj_load", "err %d\n", err))
+ goto cleanup;
+ inst[i].obj = obj;
+
+ if (rand() % 2) {
+ link = load(obj, fentry_name);
+ if (CHECK(IS_ERR(link), "attach prog", "err %ld\n", PTR_ERR(link)))
+ goto cleanup;
+ inst[i].link_fentry = link;
+ } else {
+ link = load(obj, fexit_name);
+ if (CHECK(IS_ERR(link), "attach prog", "err %ld\n", PTR_ERR(link)))
+ goto cleanup;
+ inst[i].link_fexit = link;
+ }
+ }
+
+ /* and try 1 extra.. */
+ obj = bpf_object__open_file(object, NULL);
+ if (CHECK(IS_ERR(obj), "obj_open_file", "err %ld\n", PTR_ERR(obj)))
+ goto cleanup;
+
+ err = bpf_object__load(obj);
+ if (CHECK(err, "obj_load", "err %d\n", err))
+ goto cleanup_extra;
+
+ /* ..that needs to fail */
+ link = load(obj, fentry_name);
+ if (CHECK(!IS_ERR(link), "cannot attach over the limit", "err %ld\n", PTR_ERR(link))) {
+ bpf_link__destroy(link);
+ goto cleanup_extra;
+ }
+
+ /* with E2BIG error */
+ CHECK(PTR_ERR(link) != -E2BIG, "proper error check", "err %ld\n", PTR_ERR(link));
+
+ /* and finaly execute the probe */
+ if (CHECK_FAIL(prctl(PR_GET_NAME, comm, 0L, 0L, 0L)))
+ goto cleanup_extra;
+ CHECK_FAIL(test_task_rename());
+ CHECK_FAIL(prctl(PR_SET_NAME, comm, 0L, 0L, 0L));
+
+cleanup_extra:
+ bpf_object__close(obj);
+cleanup:
+ while (--i) {
+ bpf_link__destroy(inst[i].link_fentry);
+ bpf_link__destroy(inst[i].link_fexit);
+ bpf_object__close(inst[i].obj);
+ }
+}
diff --git a/tools/testing/selftests/bpf/progs/test_trampoline_count.c b/tools/testing/selftests/bpf/progs/test_trampoline_count.c
new file mode 100644
index 000000000000..e51e6e3a81c2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_trampoline_count.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdbool.h>
+#include <stddef.h>
+#include <linux/bpf.h>
+#include "bpf_trace_helpers.h"
+
+struct task_struct;
+
+SEC("fentry/__set_task_comm")
+int BPF_PROG(prog1, struct task_struct *tsk, const char *buf, bool exec)
+{
+ return 0;
+}
+
+SEC("fexit/__set_task_comm")
+int BPF_PROG(prog2, struct task_struct *tsk, const char *buf, bool exec)
+{
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.24.1
