selftests/bpf: add __arg_ctx BTF rewrite test

Add a test validating that libbpf uploads BTF and func_info with
rewritten type information for arguments of global subprogs that are
marked with __arg_ctx tag.

Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240104013847.3875810-10-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c b/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c
index e0879df38639b2a4369c05c344dd59bdbc4a422c..67d4ef9e62b378de8888b326495514f26d7b169d 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c
@@ -20,6 +20,109 @@
 #include "test_global_func17.skel.h"
 #include "test_global_func_ctx_args.skel.h"
 
+#include "bpf/libbpf_internal.h"
+#include "btf_helpers.h"
+
+static void check_ctx_arg_type(const struct btf *btf, const struct btf_param *p)
+{
+       const struct btf_type *t;
+       const char *s;
+
+       t = btf__type_by_id(btf, p->type);
+       if (!ASSERT_EQ(btf_kind(t), BTF_KIND_PTR, "ptr_t"))
+               return;
+
+       s = btf_type_raw_dump(btf, t->type);
+       if (!ASSERT_HAS_SUBSTR(s, "STRUCT 'bpf_perf_event_data' size=0 vlen=0",
+                              "ctx_struct_t"))
+               return;
+}
+
+static void subtest_ctx_arg_rewrite(void)
+{
+       struct test_global_func_ctx_args *skel = NULL;
+       struct bpf_prog_info info;
+       char func_info_buf[1024] __attribute__((aligned(8)));
+       struct bpf_func_info_min *rec;
+       struct btf *btf = NULL;
+       __u32 info_len = sizeof(info);
+       int err, fd, i;
+
+       skel = test_global_func_ctx_args__open();
+       if (!ASSERT_OK_PTR(skel, "skel_open"))
+               return;
+
+       bpf_program__set_autoload(skel->progs.arg_tag_ctx_perf, true);
+
+       err = test_global_func_ctx_args__load(skel);
+       if (!ASSERT_OK(err, "skel_load"))
+               goto out;
+
+       memset(&info, 0, sizeof(info));
+       info.func_info = ptr_to_u64(&func_info_buf);
+       info.nr_func_info = 3;
+       info.func_info_rec_size = sizeof(struct bpf_func_info_min);
+
+       fd = bpf_program__fd(skel->progs.arg_tag_ctx_perf);
+       err = bpf_prog_get_info_by_fd(fd, &info, &info_len);
+       if (!ASSERT_OK(err, "prog_info"))
+               goto out;
+
+       if (!ASSERT_EQ(info.nr_func_info, 3, "nr_func_info"))
+               goto out;
+
+       btf = btf__load_from_kernel_by_id(info.btf_id);
+       if (!ASSERT_OK_PTR(btf, "obj_kern_btf"))
+               goto out;
+
+       rec = (struct bpf_func_info_min *)func_info_buf;
+       for (i = 0; i < info.nr_func_info; i++, rec = (void *)rec + info.func_info_rec_size) {
+               const struct btf_type *fn_t, *proto_t;
+               const char *name;
+
+               if (rec->insn_off == 0)
+                       continue; /* main prog, skip */
+
+               fn_t = btf__type_by_id(btf, rec->type_id);
+               if (!ASSERT_OK_PTR(fn_t, "fn_type"))
+                       goto out;
+               if (!ASSERT_EQ(btf_kind(fn_t), BTF_KIND_FUNC, "fn_type_kind"))
+                       goto out;
+               proto_t = btf__type_by_id(btf, fn_t->type);
+               if (!ASSERT_OK_PTR(proto_t, "proto_type"))
+                       goto out;
+
+               name = btf__name_by_offset(btf, fn_t->name_off);
+               if (strcmp(name, "subprog_ctx_tag") == 0) {
+                       /* int subprog_ctx_tag(void *ctx __arg_ctx) */
+                       if (!ASSERT_EQ(btf_vlen(proto_t), 1, "arg_cnt"))
+                               goto out;
+
+                       /* arg 0 is PTR -> STRUCT bpf_perf_event_data */
+                       check_ctx_arg_type(btf, &btf_params(proto_t)[0]);
+               } else if (strcmp(name, "subprog_multi_ctx_tags") == 0) {
+                       /* int subprog_multi_ctx_tags(void *ctx1 __arg_ctx,
+                        *                            struct my_struct *mem,
+                        *                            void *ctx2 __arg_ctx)
+                        */
+                       if (!ASSERT_EQ(btf_vlen(proto_t), 3, "arg_cnt"))
+                               goto out;
+
+                       /* arg 0 is PTR -> STRUCT bpf_perf_event_data */
+                       check_ctx_arg_type(btf, &btf_params(proto_t)[0]);
+                       /* arg 2 is PTR -> STRUCT bpf_perf_event_data */
+                       check_ctx_arg_type(btf, &btf_params(proto_t)[2]);
+               } else {
+                       ASSERT_FAIL("unexpected subprog %s", name);
+                       goto out;
+               }
+       }
+
+out:
+       btf__free(btf);
+       test_global_func_ctx_args__destroy(skel);
+}
+
 void test_test_global_funcs(void)
 {
        RUN_TESTS(test_global_func1);
@@ -40,4 +143,7 @@ void test_test_global_funcs(void)
        RUN_TESTS(test_global_func16);
        RUN_TESTS(test_global_func17);
        RUN_TESTS(test_global_func_ctx_args);
+
+       if (test__start_subtest("ctx_arg_rewrite"))
+               subtest_ctx_arg_rewrite();
 }