[PATCH bpf-next 09/11] selftests/bpf: Test global kptr arrays.

[Kui-Feng Lee <thinker.li@gmail.com>]

Make sure that BPF programs can declare global kptr arrays.

An array with only one element is special case, that it treats the element
like a non-array kptr field. Nested arrays are also tested to ensure they
are handled properly.

Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
 .../selftests/bpf/prog_tests/cpumask.c        |   3 +
 .../selftests/bpf/progs/cpumask_success.c     | 147 ++++++++++++++++++
 2 files changed, 150 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/cpumask.c b/tools/testing/selftests/bpf/prog_tests/cpumask.c
index ecf89df78109..bba601e235f6 100644
--- a/tools/testing/selftests/bpf/prog_tests/cpumask.c
+++ b/tools/testing/selftests/bpf/prog_tests/cpumask.c
@@ -18,6 +18,9 @@ static const char * const cpumask_success_testcases[] = {
 	"test_insert_leave",
 	"test_insert_remove_release",
 	"test_global_mask_rcu",
+	"test_global_mask_array_one_rcu",
+	"test_global_mask_array_rcu",
+	"test_global_mask_array_l2_rcu",
 	"test_cpumask_weight",
 };
 
diff --git a/tools/testing/selftests/bpf/progs/cpumask_success.c b/tools/testing/selftests/bpf/progs/cpumask_success.c
index 7a1e64c6c065..9d76d85680d7 100644
--- a/tools/testing/selftests/bpf/progs/cpumask_success.c
+++ b/tools/testing/selftests/bpf/progs/cpumask_success.c
@@ -11,6 +11,9 @@
 char _license[] SEC("license") = "GPL";
 
 int pid, nr_cpus;
+private(MASK) static struct bpf_cpumask __kptr * global_mask_array[2];
+private(MASK) static struct bpf_cpumask __kptr * global_mask_array_l2[2][1];
+private(MASK) static struct bpf_cpumask __kptr * global_mask_array_one[1];
 
 static bool is_test_task(void)
 {
@@ -460,6 +463,150 @@ int BPF_PROG(test_global_mask_rcu, struct task_struct *task, u64 clone_flags)
 	return 0;
 }
 
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_global_mask_array_one_rcu, struct task_struct *task, u64 clone_flags)
+{
+	struct bpf_cpumask *local, *prev;
+
+	if (!is_test_task())
+		return 0;
+
+	/* Kptr arrays with one element are special cased, being treated
+	 * just like a single pointer.
+	 */
+
+	local = create_cpumask();
+	if (!local)
+		return 0;
+
+	prev = bpf_kptr_xchg(&global_mask_array_one[0], local);
+	if (prev) {
+		bpf_cpumask_release(prev);
+		err = 3;
+		return 0;
+	}
+
+	bpf_rcu_read_lock();
+	local = global_mask_array_one[0];
+	if (!local) {
+		err = 4;
+		bpf_rcu_read_unlock();
+		return 0;
+	}
+
+	bpf_rcu_read_unlock();
+
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_global_mask_array_rcu, struct task_struct *task, u64 clone_flags)
+{
+	struct bpf_cpumask *local;
+
+	if (!is_test_task())
+		return 0;
+
+	/* Check if two kptrs in the array work and independently */
+
+	local = create_cpumask();
+	if (!local)
+		return 0;
+
+	bpf_rcu_read_lock();
+
+	local = bpf_kptr_xchg(&global_mask_array[0], local);
+	if (local) {
+		err = 1;
+		goto err_exit;
+	}
+
+	/* global_mask_array => [<mask>, NULL] */
+	if (!global_mask_array[0] || global_mask_array[1]) {
+		err = 2;
+		goto err_exit;
+	}
+
+	local = create_cpumask();
+	if (!local) {
+		err = 9;
+		goto err_exit;
+	}
+
+	local = bpf_kptr_xchg(&global_mask_array[1], local);
+	if (local) {
+		err = 10;
+		goto err_exit;
+	}
+
+	/* global_mask_array => [<mask 1>, <mask 2>] */
+	if (!global_mask_array[0] || !global_mask_array[1] ||
+	    global_mask_array[0] == global_mask_array[1]) {
+		err = 11;
+		goto err_exit;
+	}
+
+err_exit:
+	if (local)
+		bpf_cpumask_release(local);
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_global_mask_array_l2_rcu, struct task_struct *task, u64 clone_flags)
+{
+	struct bpf_cpumask *local;
+
+	if (!is_test_task())
+		return 0;
+
+	/* Check if two kptrs in the array work and independently */
+
+	local = create_cpumask();
+	if (!local)
+		return 0;
+
+	bpf_rcu_read_lock();
+
+	local = bpf_kptr_xchg(&global_mask_array_l2[0][0], local);
+	if (local) {
+		err = 1;
+		goto err_exit;
+	}
+
+	/* global_mask_array => [[<mask>], [NULL]] */
+	if (!global_mask_array_l2[0][0] || global_mask_array_l2[1][0]) {
+		err = 2;
+		goto err_exit;
+	}
+
+	local = create_cpumask();
+	if (!local) {
+		err = 9;
+		goto err_exit;
+	}
+
+	local = bpf_kptr_xchg(&global_mask_array_l2[1][0], local);
+	if (local) {
+		err = 10;
+		goto err_exit;
+	}
+
+	/* global_mask_array => [[<mask 1>], [<mask 2>]] */
+	if (!global_mask_array_l2[0][0] || !global_mask_array_l2[1][0] ||
+	    global_mask_array_l2[0][0] == global_mask_array_l2[1][0]) {
+		err = 11;
+		goto err_exit;
+	}
+
+err_exit:
+	if (local)
+		bpf_cpumask_release(local);
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
 SEC("tp_btf/task_newtask")
 int BPF_PROG(test_cpumask_weight, struct task_struct *task, u64 clone_flags)
 {
-- 
2.34.1