[PATCH v2 2/2] selftests/bpf: add BTF dedup tests for recursive typedef definitions

[Paul Houssel]

Add several ./test_progs tests:
    1.  btf/dedup:recursive typedef ensures that deduplication no
        longer fails on recursive typedefs.
    2.  btf/dedup:typedef ensures that typedefs are deduplicated correctly
        just as they were before this patch.

Signed-off-by: Paul Houssel <paul.hous...@orange.com>
---
 tools/testing/selftests/bpf/prog_tests/btf.c | 61 ++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c 
b/tools/testing/selftests/bpf/prog_tests/btf.c
index 8a9ba4292109..a19db159475a 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf.c
@@ -7495,6 +7495,67 @@ static struct btf_dedup_test dedup_tests[] = {
                BTF_STR_SEC("\0t\0m1\0m2\0tag1\0tag2\0tag3"),
        },
 },
+{
+       .descr = "dedup: recursive typedef",
+       /*
+        * This test simulates a recursive typedef, which in GO is defined as 
such:
+        *
+        *   type Foo func() Foo
+        *
+        * In BTF terms, this is represented as a TYPEDEF referencing
+        * a FUNC_PROTO that returns the same TYPEDEF.
+        */
+       .input = {
+               .raw_types = {
+                       /*
+                        * [1] typedef Foo -> func() Foo
+                        * [2] func_proto() -> Foo
+                        */
+                       BTF_TYPEDEF_ENC(NAME_NTH(1), 2),        /* [1] */
+                       BTF_FUNC_PROTO_ENC(1, 0),               /* [2] */
+                       BTF_END_RAW,
+               },
+               BTF_STR_SEC("\0Foo"),
+       },
+       .expect = {
+               .raw_types = {
+                       BTF_TYPEDEF_ENC(NAME_NTH(1), 2),        /* [1] */
+                       BTF_FUNC_PROTO_ENC(1, 0),               /* [2] */
+                       BTF_END_RAW,
+               },
+               BTF_STR_SEC("\0Foo"),
+       },
+},
+{
+       .descr = "dedup: typedef",
+    /*
+     * // CU 1:
+     * typedef int foo;
+     *
+     * // CU 2:
+     * typedef int foo;
+     */
+       .input = {
+               .raw_types = {
+                       /* CU 1 */
+                       BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] 
*/
+                       BTF_TYPEDEF_ENC(NAME_NTH(1), 1),                /* [2] 
*/
+                       /* CU 2 */
+                       BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [3] 
*/
+                       BTF_TYPEDEF_ENC(NAME_NTH(1), 3),                /* [4] 
*/
+                       BTF_END_RAW,
+               },
+               BTF_STR_SEC("\0foo"),
+       },
+       .expect = {
+               .raw_types = {
+                       BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] 
*/
+                       BTF_TYPEDEF_ENC(NAME_NTH(1), 1),                /* [2] 
*/
+                       BTF_END_RAW,
+               },
+               BTF_STR_SEC("\0foo"),
+       },
+},
 {
        .descr = "dedup: typedef tags",
        .input = {
-- 
2.51.0