Commit e02feb3f authored by Dmitrii Dolgov's avatar Dmitrii Dolgov Committed by Alexei Starovoitov
Browse files

selftests/bpf: Test re-attachment fix for bpf_tracing_prog_attach 



Add a test case to verify the fix for "prog->aux->dst_trampoline and
tgt_prog is NULL" branch in bpf_tracing_prog_attach. The sequence of
events:

1. load rawtp program
2. load fentry program with rawtp as target_fd
3. create tracing link for fentry program with target_fd = 0
4. repeat 3

Acked-by: default avatarJiri Olsa <olsajiri@gmail.com>
Acked-by: default avatarSong Liu <song@kernel.org>
Signed-off-by: default avatarDmitrii Dolgov <9erthalion6@gmail.com>
Link: https://lore.kernel.org/r/20240103190559.14750-5-9erthalion6@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 715d82ba

tools/testing/selftests/bpf/prog_tests/recursive_attach.c

+44 −0
Original line number Diff line number Diff line
@@ -105,3 +105,47 @@ void test_recursive_fentry(void) 
	if (test__start_subtest("detach"))

		test_recursive_fentry_chain(true, true);

}



/* Test that a tracing prog reattachment (when we land in

 * "prog->aux->dst_trampoline and tgt_prog is NULL" branch in

 * bpf_tracing_prog_attach) does not lead to a crash due to missing attach_btf

 */

void test_fentry_attach_btf_presence(void)

{

	struct fentry_recursive_target *target_skel = NULL;

	struct fentry_recursive *tracing_skel = NULL;

	struct bpf_program *prog;

	int err, link_fd, tgt_prog_fd;



	target_skel = fentry_recursive_target__open_and_load();

	if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))

		goto close_prog;



	tracing_skel = fentry_recursive__open();

	if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open"))

		goto close_prog;



	prog = tracing_skel->progs.recursive_attach;

	tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target);

	err = bpf_program__set_attach_target(prog, tgt_prog_fd, "fentry_target");

	if (!ASSERT_OK(err, "bpf_program__set_attach_target"))

		goto close_prog;



	err = fentry_recursive__load(tracing_skel);

	if (!ASSERT_OK(err, "fentry_recursive__load"))

		goto close_prog;



	tgt_prog_fd = bpf_program__fd(tracing_skel->progs.recursive_attach);

	link_fd = bpf_link_create(tgt_prog_fd, 0, BPF_TRACE_FENTRY, NULL);

	if (!ASSERT_GE(link_fd, 0, "link_fd"))

		goto close_prog;



	fentry_recursive__detach(tracing_skel);



	err = fentry_recursive__attach(tracing_skel);

	ASSERT_ERR(err, "fentry_recursive__attach");



close_prog:

	fentry_recursive_target__destroy(target_skel);

	fentry_recursive__destroy(tracing_skel);

}

tools/testing/selftests/bpf/progs/fentry_recursive_target.c

+9 −0
Original line number Diff line number Diff line
@@ -14,3 +14,12 @@ int BPF_PROG(test1, int a) 
{

	return 0;

}



/* Dummy bpf prog for testing attach_btf presence when attaching an fentry

 * program.

 */

SEC("raw_tp/sys_enter")

int BPF_PROG(fentry_target, struct pt_regs *regs, long id)

{

	return 0;

}