selftests/bpf: Add a test case for kptr_rcu.

Tweak existing map_kptr test to check kptr_rcu.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230303041446.3630-5-alexei.starovoitov@gmail.com

diff --git a/tools/testing/selftests/bpf/progs/map_kptr.c b/tools/testing/selftests/bpf/progs/map_kptr.c
index 3fe7cde..3903d30 100644 (file)
--- a/tools/testing/selftests/bpf/progs/map_kptr.c
+++ b/tools/testing/selftests/bpf/progs/map_kptr.c
@@ -118,6 +118,7 @@ extern struct prog_test_ref_kfunc *bpf_kfunc_call_test_acquire(unsigned long *sp
 extern struct prog_test_ref_kfunc *
 bpf_kfunc_call_test_kptr_get(struct prog_test_ref_kfunc **p, int a, int b) __ksym;
 extern void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) __ksym;
+void bpf_kfunc_call_test_ref(struct prog_test_ref_kfunc *p) __ksym;
 
 #define WRITE_ONCE(x, val) ((*(volatile typeof(x) *) &(x)) = (val))
 
@@ -147,12 +148,23 @@ static void test_kptr_ref(struct map_value *v)
        WRITE_ONCE(v->unref_ptr, p);
        if (!p)
                return;
+       /*
+        * p is rcu_ptr_prog_test_ref_kfunc,
+        * because bpf prog is non-sleepable and runs in RCU CS.
+        * p can be passed to kfunc that requires KF_RCU.
+        */
+       bpf_kfunc_call_test_ref(p);
        if (p->a + p->b > 100)
                return;
        /* store NULL */
        p = bpf_kptr_xchg(&v->ref_ptr, NULL);
        if (!p)
                return;
+       /*
+        * p is trusted_ptr_prog_test_ref_kfunc.
+        * p can be passed to kfunc that requires KF_RCU.
+        */
+       bpf_kfunc_call_test_ref(p);
        if (p->a + p->b > 100) {
                bpf_kfunc_call_test_release(p);
                return;