From: Alexei Starovoitov <ast@xxxxxxxxxx>
Add load and run time test for bpf_kfunc_exists() and check that the verifier
performs dead code elimination for non-existing kfunc.
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
.../selftests/bpf/progs/task_kfunc_success.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_success.c b/tools/testing/selftests/bpf/progs/task_kfunc_success.c
index 4f61596b0242..c0a7774e0c79 100644
--- a/tools/testing/selftests/bpf/progs/task_kfunc_success.c
+++ b/tools/testing/selftests/bpf/progs/task_kfunc_success.c
@@ -17,6 +17,8 @@ int err, pid;
* TP_PROTO(struct task_struct *p, u64 clone_flags)
*/
+void invalid_kfunc(void) __ksym __weak;
+
static bool is_test_kfunc_task(void)
{
int cur_pid = bpf_get_current_pid_tgid() >> 32;
@@ -26,7 +28,17 @@ static bool is_test_kfunc_task(void)
static int test_acquire_release(struct task_struct *task)
{
- struct task_struct *acquired;
+ struct task_struct *acquired = NULL;
+
+ if (!bpf_kfunc_exists(bpf_task_acquire)) {
+ err = 3;
+ return 0;
+ }
+ if (bpf_kfunc_exists(invalid_kfunc)) {
+ /* the verifier's dead code elimination should remove this */
+ err = 4;
+ asm volatile ("goto -1"); /* for (;;); */
+ }
acquired = bpf_task_acquire(task);
bpf_task_release(acquired);
--
2.34.1
