selftests/bpf: Test resolve_btfids arena argument suffixes

Add a suffix-only kfunc declaration with arena annotations on all five
arguments. Verify that resolve_btfids emits address_space(1) type tags
for every position without KF_ARENA_ARG flags in the BTF ID sets.

Represent expected arena arguments as a per-parameter bitmap so the
test covers suffixes beyond the two positions expressible by flags.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://patch.msgid.link/20260812193842.2879226-3-memxor@gmail.com
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/btf_data.c b/tools/testing/selftests/bpf/progs/btf_data.c
index ec34f7a6e038..8082c13490ab 100644
--- a/tools/testing/selftests/bpf/progs/btf_data.c
+++ b/tools/testing/selftests/bpf/progs/btf_data.c
@@ -68,3 +68,23 @@ int kfunc_d(struct root_struct *a, struct root_struct *b)
 {
 	return 0;
 }
+
+int kfunc_e(struct root_struct *a__arena,
+	    struct root_struct *b__arena__nullable,
+	    struct root_struct *c__arena,
+	    struct root_struct *d__arena__nullable,
+	    struct root_struct *e__arena)
+{
+	return 0;
+}
+
+int kfunc_f(struct root_struct *a, struct root_struct *b__arena, int flags)
+{
+	return 0;
+}
+
+struct root_struct *kfunc_g(struct root_struct *a__arena,
+			    struct root_struct *b__arena__nullable)
+{
+	return a__arena;
+}