[PATCH bpf-next 14/15] selftests/bpf: Add some negative tests

[Yonghong Song <yonghong.song@xxxxxxxxx>]

Add a few negative tests for common mistakes with using percpu kptr.
Other similar error cases occuring with bpf_obj_new/drop() are not
included here.

Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx>
---
 .../selftests/bpf/prog_tests/percpu_alloc.c   |   7 ++
 .../selftests/bpf/progs/percpu_alloc_fail.c   | 100 ++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/percpu_alloc_fail.c

diff --git a/tools/testing/selftests/bpf/prog_tests/percpu_alloc.c b/tools/testing/selftests/bpf/prog_tests/percpu_alloc.c
index ee9dd495db7b..17ba3159cea7 100644
--- a/tools/testing/selftests/bpf/prog_tests/percpu_alloc.c
+++ b/tools/testing/selftests/bpf/prog_tests/percpu_alloc.c
@@ -3,6 +3,7 @@
 #include "percpu_alloc_array.skel.h"
 #include "percpu_alloc_cgrp_local_storage.skel.h"
 #include "percpu_alloc_nested_special_fields.skel.h"
+#include "percpu_alloc_fail.skel.h"
 
 static void test_array(void)
 {
@@ -145,6 +146,10 @@ static void test_nested_special_fields(void)
 	close(cgroup_fd);
 }
 
+static void test_failure(void) {
+	RUN_TESTS(percpu_alloc_fail);
+}
+
 void test_percpu_alloc(void)
 {
 	if (test__start_subtest("array"))
@@ -155,4 +160,6 @@ void test_percpu_alloc(void)
 		test_cgrp_local_storage();
 	if (test__start_subtest("nested_special_fields"))
 		test_nested_special_fields();
+	if (test__start_subtest("failure_tests"))
+		test_failure();
 }
diff --git a/tools/testing/selftests/bpf/progs/percpu_alloc_fail.c b/tools/testing/selftests/bpf/progs/percpu_alloc_fail.c
new file mode 100644
index 000000000000..47bdf6f857cb
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/percpu_alloc_fail.c
@@ -0,0 +1,100 @@
+#include "bpf_experimental.h"
+#include "bpf_misc.h"
+
+struct val_t {
+	long b, c, d;
+};
+
+struct val2_t {
+	long b;
+};
+
+struct elem {
+	long sum;
+	struct val_t __percpu *pc;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, int);
+	__type(value, struct elem);
+} array SEC(".maps");
+
+long ret;
+
+SEC("?fentry/bpf_fentry_test1")
+__failure __msg("store to referenced kptr disallowed")
+int BPF_PROG(test_array_map_1)
+{
+	struct val_t __percpu *p;
+	struct elem *e;
+	int index = 0;
+
+	e = bpf_map_lookup_elem(&array, &index);
+	if (!e)
+		return 0;
+
+	p = bpf_percpu_obj_new(struct val_t);
+	if (!p)
+		return 0;
+
+	p = bpf_kptr_xchg(&e->pc, p);
+	if (p)
+		bpf_percpu_obj_drop(p);
+
+	e->pc = (struct val_t __percpu *)ret;
+	return 0;
+}
+
+SEC("?fentry/bpf_fentry_test1")
+__failure __msg("invalid kptr access, R2 type=percpu_ptr_val2_t expected=ptr_val_t")
+int BPF_PROG(test_array_map_2)
+{
+	struct val2_t __percpu *p2;
+	struct val_t __percpu *p;
+	struct elem *e;
+	int index = 0;
+
+	e = bpf_map_lookup_elem(&array, &index);
+	if (!e)
+		return 0;
+
+	p2 = bpf_percpu_obj_new(struct val2_t);
+	if (!p2)
+		return 0;
+
+	p = bpf_kptr_xchg(&e->pc, p2);
+	if (p)
+		bpf_percpu_obj_drop(p);
+
+	return 0;
+}
+
+SEC("?fentry.s/bpf_fentry_test1")
+__failure __msg("R1 type=scalar expected=percpu_ptr_, percpu_rcu_ptr_, percpu_trusted_ptr_")
+int BPF_PROG(test_array_map_3)
+{
+	struct val_t __percpu *p, *p1;
+	struct val_t *v;
+	struct elem *e;
+	int index = 0;
+
+	e = bpf_map_lookup_elem(&array, &index);
+	if (!e)
+		return 0;
+
+	p = bpf_percpu_obj_new(struct val_t);
+	if (!p)
+		return 0;
+
+	p1 = bpf_kptr_xchg(&e->pc, p);
+	if (p1)
+		bpf_percpu_obj_drop(p1);
+
+	v = bpf_this_cpu_ptr(p);
+	ret = v->b;
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.34.1