Commit 95fdf6e3 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Andrii Nakryiko
Browse files

selftests/bpf: Add test for bpf_ksym_exists(). 



Add load and run time test for bpf_ksym_exists() and check that the verifier
performs dead code elimination for non-existing kfunc.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Reviewed-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20230317201920.62030-5-alexei.starovoitov@gmail.com
parent 5cbd3fe3

tools/testing/selftests/bpf/progs/task_kfunc_success.c

+19 −1
Original line number Diff line number Diff line
@@ -17,6 +17,10 @@ int err, pid; 
 *         TP_PROTO(struct task_struct *p, u64 clone_flags)

 */



struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym __weak;

void invalid_kfunc(void) __ksym __weak;

void bpf_testmod_test_mod_kfunc(int i) __ksym __weak;



static bool is_test_kfunc_task(void)

{

	int cur_pid = bpf_get_current_pid_tgid() >> 32;
@@ -26,7 +30,21 @@ 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_ksym_exists(bpf_task_acquire)) {

		err = 3;

		return 0;

	}

	if (!bpf_ksym_exists(bpf_testmod_test_mod_kfunc)) {

		err = 4;

		return 0;

	}

	if (bpf_ksym_exists(invalid_kfunc)) {

		/* the verifier's dead code elimination should remove this */

		err = 5;

		asm volatile ("goto -1"); /* for (;;); */

	}



	acquired = bpf_task_acquire(task);

	bpf_task_release(acquired);