[PATCH sched_ext/for-7.5] selftests/sched_ext: Fix enable_cmask load failure on older clangs

[Tejun Heo]

enable_cmask casts the u64 arena address of the task's cmask to an __arena
pointer without cast_kern(). Older clangs without
__BPF_FEATURE_ADDR_SPACE_CAST need the explicit cast, so the test fails to
load there. Add it.

Reported-by: Zhijian Han <hanzhijian1991@xxxxxxxxx>
Closes: https://lore.kernel.org/all/6af1e5f2.a438010f.130489.ab94@xxxxxxxxxxxxx/
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
Applied to sched_ext/for-7.5.

 tools/testing/selftests/sched_ext/enable_cmask.bpf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/sched_ext/enable_cmask.bpf.c b/tools/testing/selftests/sched_ext/enable_cmask.bpf.c
index 0068f3c7ab3c..081be5861424 100644
--- a/tools/testing/selftests/sched_ext/enable_cmask.bpf.c
+++ b/tools/testing/selftests/sched_ext/enable_cmask.bpf.c
@@ -104,6 +104,7 @@ void BPF_STRUCT_OPS(enable_cmask_enable, struct task_struct *p, struct scx_enabl
 	int ret;
 
 	asm volatile("" :: "r"(&arena));
+	cast_kern(m);
 	tctx = lookup_task_ctx(p);
 	if (!tctx)
 		return;
-- 
2.56.0