Commit af90e853 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 's390-bpf-fix-bpf_arch_text_poke-with-new_addr-null-again' 

Ilya Leoshkevich says:

====================
s390/bpf: Fix bpf_arch_text_poke() with new_addr == NULL again

This series fixes a regression causing perf on s390 to trigger a kernel
panic.

Patch 1 fixes the issue, patch 2 adds a test to make sure this doesn't
happen again.
====================

Link: https://patch.msgid.link/20250716194524.48109-1-iii@linux.ibm.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents bf4807c8 d459dbbb

arch/s390/net/bpf_jit_comp.c

+9 −1
Original line number Diff line number Diff line
@@ -566,7 +566,15 @@ static void bpf_jit_plt(struct bpf_plt *plt, void *ret, void *target) 
{

	memcpy(plt, &bpf_plt, sizeof(*plt));

	plt->ret = ret;

	plt->target = target;

	/*

	 * (target == NULL) implies that the branch to this PLT entry was

	 * patched and became a no-op. However, some CPU could have jumped

	 * to this PLT entry before patching and may be still executing it.

	 *

	 * Since the intention in this case is to make the PLT entry a no-op,

	 * make the target point to the return label instead of NULL.

	 */

	plt->target = target ?: ret;

}



/*

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

+67 −0
Original line number Diff line number Diff line
@@ -149,3 +149,70 @@ void test_fentry_attach_btf_presence(void) 
	fentry_recursive_target__destroy(target_skel);

	fentry_recursive__destroy(tracing_skel);

}



static void *fentry_target_test_run(void *arg)

{

	for (;;) {

		int prog_fd = __atomic_load_n((int *)arg, __ATOMIC_SEQ_CST);

		LIBBPF_OPTS(bpf_test_run_opts, topts);

		int err;



		if (prog_fd == -1)

			break;

		err = bpf_prog_test_run_opts(prog_fd, &topts);

		if (!ASSERT_OK(err, "fentry_target test_run"))

			break;

	}



	return NULL;

}



void test_fentry_attach_stress(void)

{

	struct fentry_recursive_target *target_skel = NULL;

	struct fentry_recursive *tracing_skel = NULL;

	struct bpf_program *prog;

	int err, i, tgt_prog_fd;

	pthread_t thread;



	target_skel = fentry_recursive_target__open_and_load();

	if (!ASSERT_OK_PTR(target_skel,

			   "fentry_recursive_target__open_and_load"))

		goto close_prog;

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

	err = pthread_create(&thread, NULL,

			     fentry_target_test_run, &tgt_prog_fd);

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

		goto close_prog;



	for (i = 0; i < 1000; i++) {

		tracing_skel = fentry_recursive__open();

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

			goto stop_thread;



		prog = tracing_skel->progs.recursive_attach;

		err = bpf_program__set_attach_target(prog, tgt_prog_fd,

						     "fentry_target");

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

			goto stop_thread;



		err = fentry_recursive__load(tracing_skel);

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

			goto stop_thread;



		err = fentry_recursive__attach(tracing_skel);

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

			goto stop_thread;



		fentry_recursive__destroy(tracing_skel);

		tracing_skel = NULL;

	}



stop_thread:

	__atomic_store_n(&tgt_prog_fd, -1, __ATOMIC_SEQ_CST);

	err = pthread_join(thread, NULL);

	ASSERT_OK(err, "pthread_join");

close_prog:

	fentry_recursive__destroy(tracing_skel);

	fentry_recursive_target__destroy(target_skel);

}