[PATCH bpf-next v1 4/4] selftests/bpf: Test accessing struct_ops this pointer in timer callback

[Amery Hung <ameryhung@gmail.com>]

Check accessing aux->this_st_ops in timer callback. Make sure a kfunc in
a timer callback can get a correct this pointer when a struct_ops map is
attached, and NULL after the map is detached.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
---
 .../bpf/prog_tests/test_struct_ops_this_ptr.c | 51 ++++++++++++++++
 .../bpf/progs/struct_ops_this_ptr_in_timer.c  | 60 +++++++++++++++++++
 .../selftests/bpf/test_kmods/bpf_testmod.c    |  1 +
 3 files changed, 112 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_this_ptr_in_timer.c

diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_this_ptr.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_this_ptr.c
index 6ef238a2050a..933f9310f462 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_this_ptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_this_ptr.c
@@ -3,8 +3,59 @@
 #include <test_progs.h>
 
 #include "struct_ops_this_ptr.skel.h"
+#include "struct_ops_this_ptr_in_timer.skel.h"
+
+static void test_struct_ops_this_ptr_in_timer_common(int timer_nsec, int expected_data)
+{
+	struct struct_ops_this_ptr_in_timer *skel;
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+	struct bpf_link *link;
+	int err, prog_fd;
+
+	skel = struct_ops_this_ptr_in_timer__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+		return;
+
+	skel->bss->timer_nsec = timer_nsec;
+
+	link = bpf_map__attach_struct_ops(skel->maps.testmod_this_ptr);
+	if (!ASSERT_OK_PTR(link, "bpf_map__attach_struct_ops"))
+		goto out;
+
+	prog_fd = bpf_program__fd(skel->progs.syscall_this_ptr_in_timer);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "bpf_prog_test_run_opts");
+
+	bpf_link__destroy(link);
+
+	/* Check st_ops3_data after timer_cb runs */
+	while (!READ_ONCE(skel->bss->st_ops3_data))
+		sched_yield();
+	ASSERT_EQ(skel->bss->st_ops3_data, expected_data, "st_ops->data");
+out:
+	struct_ops_this_ptr_in_timer__destroy(skel);
+}
+
+static void test_struct_ops_this_ptr_in_timer(void)
+{
+	/* Run timer callback immediately */
+	test_struct_ops_this_ptr_in_timer_common(0, 1234);
+}
+
+static void test_struct_ops_this_ptr_in_timer_after_detach(void)
+{
+	/*
+	 * Run timer callback 0.1s after test run. By then the struct_ops map
+	 * should have been detached.
+	 */
+	test_struct_ops_this_ptr_in_timer_common(100000000, -1);
+}
 
 void serial_test_struct_ops_this_ptr(void)
 {
 	RUN_TESTS(struct_ops_this_ptr);
+	if (test__start_subtest("struct_ops_this_ptr_in_timer"))
+		test_struct_ops_this_ptr_in_timer();
+	if (test__start_subtest("struct_ops_this_ptr_in_timer_after_detach"))
+		test_struct_ops_this_ptr_in_timer_after_detach();
 }
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_this_ptr_in_timer.c b/tools/testing/selftests/bpf/progs/struct_ops_this_ptr_in_timer.c
new file mode 100644
index 000000000000..e5f76945e967
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_this_ptr_in_timer.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include "../test_kmods/bpf_testmod.h"
+#include "../test_kmods/bpf_testmod_kfunc.h"
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct elem {
+	struct bpf_timer timer;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, int);
+	__type(value, struct elem);
+} array_map SEC(".maps");
+
+int st_ops3_data;
+int timer_nsec;
+
+__noinline static int timer_cb(void *map, int *key, struct bpf_timer *timer)
+{
+	st_ops3_data = bpf_kfunc_st_ops_test_this_ptr_impl(NULL);
+	return 0;
+}
+
+SEC("struct_ops")
+int BPF_PROG(test1)
+{
+	struct bpf_timer *timer;
+	int key = 0;
+
+	timer = bpf_map_lookup_elem(&array_map, &key);
+	if (!timer)
+		return 0;
+
+	bpf_timer_init(timer, &array_map, 1);
+	bpf_timer_set_callback(timer, timer_cb);
+	bpf_timer_start(timer, timer_nsec, 0);
+	return 1;
+}
+
+SEC("syscall")
+__success __retval(1)
+int syscall_this_ptr_in_timer(void *ctx)
+{
+	return bpf_testmod_ops3_call_test_1();
+}
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops3 testmod_this_ptr = {
+	.test_1 = (void *)test1,
+	.data = 1234,
+};
+
+
diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
index f692ee43d25c..65953cd63b7c 100644
--- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
@@ -1157,6 +1157,7 @@ static const struct bpf_verifier_ops bpf_testmod_verifier_ops = {
 };
 
 static const struct bpf_verifier_ops bpf_testmod_verifier_ops3 = {
+	.get_func_proto	 = bpf_base_func_proto,
 	.is_valid_access = bpf_testmod_ops_is_valid_access,
 };
 
-- 
2.47.1