[PATCH bpf-next v1 07/14] selftests/bpf: Test kfunc argument diagnostics

Extend existing negative kfunc programs to assert that BTF void is rendered
as void and that variable __szk arguments receive a structured constant-size
diagnostic.

Also pass a context pointer to bpf_refcount_acquire() and verify that the
report describes the generic refcounted-object contract and the actual
argument type. Retain the legacy verbose-message assertions.

Link: https://lore.kernel.org/bpf/3eda33675965763aa9b2e6a5784f32b34a6a83988a55fbea98b0dbd0cf3b088d@mail.kernel.org/
Signed-off-by: Kumar Kartikeya Dwivedi <[email protected]>
---
 tools/testing/selftests/bpf/progs/dynptr_fail.c          | 2 ++
 tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/dynptr_fail.c b/tools/testing/selftests/bpf/progs/dynptr_fail.c
index 72aa6b5a877b..9418dfe4d7b7 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_fail.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_fail.c
@@ -1593,6 +1593,7 @@ __u32 hdr_size = sizeof(struct ethhdr);
 /* Can't pass in variable-sized len to bpf_dynptr_slice */
 SEC("?tc")
 __failure __msg("must be a known constant")
+__msg("requires this memory size to be a verifier-known constant")
 int dynptr_slice_var_len1(struct __sk_buff *skb)
 {
 	struct bpf_dynptr ptr;
@@ -1612,6 +1613,7 @@ int dynptr_slice_var_len1(struct __sk_buff *skb)
 /* Can't pass in variable-sized len to bpf_dynptr_slice */
 SEC("?tc")
 __failure __msg("must be a known constant")
+__msg("requires this memory size to be a verifier-known constant")
 int dynptr_slice_var_len2(struct __sk_buff *skb)
 {
 	char buffer[sizeof(struct ethhdr)] = {};
diff --git a/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c b/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c
index 024ef2aae200..eaaed0859f94 100644
--- a/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c
+++ b/tools/testing/selftests/bpf/progs/refcounted_kptr_fail.c
@@ -63,6 +63,7 @@ long rbtree_refcounted_node_ref_escapes(void *ctx)
 
 SEC("?tc")
 __failure __msg("Possibly NULL pointer passed to trusted R1")
+__msg("requires a non-NULL value of type (void *)")
 long refcount_acquire_maybe_null(void *ctx)
 {
 	struct node_acquire *n, *m;
@@ -80,6 +81,14 @@ long refcount_acquire_maybe_null(void *ctx)
 	return 0;
 }
 
+SEC("?tc")
+__failure __msg("R1 is neither owning or non-owning ref")
+__msg("expects a pointer to a BPF-managed refcounted object, but R1 is a context pointer")
+long refcount_acquire_non_object(void *ctx)
+{
+	return bpf_refcount_acquire(ctx) != NULL;
+}
+
 SEC("?tc")
 __failure __msg("Unreleased reference id=3 alloc_insn={{[0-9]+}}")
 long rbtree_refcounted_node_ref_escapes_owning_input(void *ctx)
-- 
2.53.0