selftests/bpf: Use both syntaxes for field-based CO-RE helpers

Excercise both supported forms of bpf_core_field_exists() and
bpf_core_field_size() helpers: variable-based field reference and
type/field name-based one.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220509004148.1801791-5-andrii@kernel.org

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

@@ -45,35 +45,34 @@ int test_core_existence(void *ctx)
 	struct core_reloc_existence_output *out = (void *)&data.out;
 
 	out->a_exists = bpf_core_field_exists(in->a);
-	if (bpf_core_field_exists(in->a))
+	if (bpf_core_field_exists(struct core_reloc_existence, a))
 		out->a_value = BPF_CORE_READ(in, a);
 	else
 		out->a_value = 0xff000001u;
 
 	out->b_exists = bpf_core_field_exists(in->b);
-	if (bpf_core_field_exists(in->b))
+	if (bpf_core_field_exists(struct core_reloc_existence, b))
 		out->b_value = BPF_CORE_READ(in, b);
 	else
 		out->b_value = 0xff000002u;
 
 	out->c_exists = bpf_core_field_exists(in->c);
-	if (bpf_core_field_exists(in->c))
+	if (bpf_core_field_exists(struct core_reloc_existence, c))
 		out->c_value = BPF_CORE_READ(in, c);
 	else
 		out->c_value = 0xff000003u;
 
 	out->arr_exists = bpf_core_field_exists(in->arr);
-	if (bpf_core_field_exists(in->arr))
+	if (bpf_core_field_exists(struct core_reloc_existence, arr))
 		out->arr_value = BPF_CORE_READ(in, arr[0]);
 	else
 		out->arr_value = 0xff000004u;
 
 	out->s_exists = bpf_core_field_exists(in->s);
-	if (bpf_core_field_exists(in->s))
+	if (bpf_core_field_exists(struct core_reloc_existence, s))
 		out->s_value = BPF_CORE_READ(in, s.x);
 	else
 		out->s_value = 0xff000005u;
 
 	return 0;
 }
-

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

@@ -44,10 +44,10 @@ int test_core_size(void *ctx)
 	out->struct_sz = bpf_core_field_size(in->struct_field);
 	out->union_sz = bpf_core_field_size(in->union_field);
 	out->arr_sz = bpf_core_field_size(in->arr_field);
-	out->arr_elem_sz = bpf_core_field_size(in->arr_field[0]);
-	out->ptr_sz = bpf_core_field_size(in->ptr_field);
-	out->enum_sz = bpf_core_field_size(in->enum_field);
-	out->float_sz = bpf_core_field_size(in->float_field);
+	out->arr_elem_sz = bpf_core_field_size(struct core_reloc_size, arr_field[0]);
+	out->ptr_sz = bpf_core_field_size(struct core_reloc_size, ptr_field);
+	out->enum_sz = bpf_core_field_size(struct core_reloc_size, enum_field);
+	out->float_sz = bpf_core_field_size(struct core_reloc_size, float_field);
 
 	return 0;
 }