selftests/bpf: Add split BTF basic test

Add selftest validating ability to programmatically generate and then dump
split BTF.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20201105043402.2530976-6-andrii@kernel.org

diff --git a/tools/testing/selftests/bpf/prog_tests/btf_split.c b/tools/testing/selftests/bpf/prog_tests/btf_split.c
new file mode 100644 (file)
index 0000000..ca7c2a9
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/btf_split.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include <test_progs.h>
+#include <bpf/btf.h>
+
+static char *dump_buf;
+static size_t dump_buf_sz;
+static FILE *dump_buf_file;
+
+static void btf_dump_printf(void *ctx, const char *fmt, va_list args)
+{
+       vfprintf(ctx, fmt, args);
+}
+
+void test_btf_split() {
+       struct btf_dump_opts opts;
+       struct btf_dump *d = NULL;
+       const struct btf_type *t;
+       struct btf *btf1, *btf2;
+       int str_off, i, err;
+
+       btf1 = btf__new_empty();
+       if (!ASSERT_OK_PTR(btf1, "empty_main_btf"))
+               return;
+
+       btf__set_pointer_size(btf1, 8); /* enforce 64-bit arch */
+
+       btf__add_int(btf1, "int", 4, BTF_INT_SIGNED);   /* [1] int */
+       btf__add_ptr(btf1, 1);                          /* [2] ptr to int */
+
+       btf__add_struct(btf1, "s1", 4);                 /* [3] struct s1 { */
+       btf__add_field(btf1, "f1", 1, 0, 0);            /*      int f1; */
+                                                       /* } */
+
+       btf2 = btf__new_empty_split(btf1);
+       if (!ASSERT_OK_PTR(btf2, "empty_split_btf"))
+               goto cleanup;
+
+       /* pointer size should be "inherited" from main BTF */
+       ASSERT_EQ(btf__pointer_size(btf2), 8, "inherit_ptr_sz");
+
+       str_off = btf__find_str(btf2, "int");
+       ASSERT_NEQ(str_off, -ENOENT, "str_int_missing");
+
+       t = btf__type_by_id(btf2, 1);
+       if (!ASSERT_OK_PTR(t, "int_type"))
+               goto cleanup;
+       ASSERT_EQ(btf_is_int(t), true, "int_kind");
+       ASSERT_STREQ(btf__str_by_offset(btf2, t->name_off), "int", "int_name");
+
+       btf__add_struct(btf2, "s2", 16);                /* [4] struct s2 {      */
+       btf__add_field(btf2, "f1", 3, 0, 0);            /*      struct s1 f1;   */
+       btf__add_field(btf2, "f2", 1, 32, 0);           /*      int f2;         */
+       btf__add_field(btf2, "f3", 2, 64, 0);           /*      int *f3;        */
+                                                       /* } */
+
+       t = btf__type_by_id(btf1, 4);
+       ASSERT_NULL(t, "split_type_in_main");
+
+       t = btf__type_by_id(btf2, 4);
+       if (!ASSERT_OK_PTR(t, "split_struct_type"))
+               goto cleanup;
+       ASSERT_EQ(btf_is_struct(t), true, "split_struct_kind");
+       ASSERT_EQ(btf_vlen(t), 3, "split_struct_vlen");
+       ASSERT_STREQ(btf__str_by_offset(btf2, t->name_off), "s2", "split_struct_name");
+
+       /* BTF-to-C dump of split BTF */
+       dump_buf_file = open_memstream(&dump_buf, &dump_buf_sz);
+       if (!ASSERT_OK_PTR(dump_buf_file, "dump_memstream"))
+               return;
+       opts.ctx = dump_buf_file;
+       d = btf_dump__new(btf2, NULL, &opts, btf_dump_printf);
+       if (!ASSERT_OK_PTR(d, "btf_dump__new"))
+               goto cleanup;
+       for (i = 1; i <= btf__get_nr_types(btf2); i++) {
+               err = btf_dump__dump_type(d, i);
+               ASSERT_OK(err, "dump_type_ok");
+       }
+       fflush(dump_buf_file);
+       dump_buf[dump_buf_sz] = 0; /* some libc implementations don't do this */
+       ASSERT_STREQ(dump_buf,
+"struct s1 {\n"
+"      int f1;\n"
+"};\n"
+"\n"
+"struct s2 {\n"
+"      struct s1 f1;\n"
+"      int f2;\n"
+"      int *f3;\n"
+"};\n\n", "c_dump");
+
+cleanup:
+       if (dump_buf_file)
+               fclose(dump_buf_file);
+       free(dump_buf);
+       btf_dump__free(d);
+       btf__free(btf1);
+       btf__free(btf2);
+}

diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
index 238f5f6..d6b1485 100644 (file)
--- a/tools/testing/selftests/bpf/test_progs.h
+++ b/tools/testing/selftests/bpf/test_progs.h
@@ -141,6 +141,17 @@ extern int test__join_cgroup(const char *path);
        ___ok;                                                          \
 })
 
+#define ASSERT_NEQ(actual, expected, name) ({                          \
+       static int duration = 0;                                        \
+       typeof(actual) ___act = (actual);                               \
+       typeof(expected) ___exp = (expected);                           \
+       bool ___ok = ___act != ___exp;                                  \
+       CHECK(!___ok, (name),                                           \
+             "unexpected %s: actual %lld == expected %lld\n",          \
+             (name), (long long)(___act), (long long)(___exp));        \
+       ___ok;                                                          \
+})
+
 #define ASSERT_STREQ(actual, expected, name) ({                                \
        static int duration = 0;                                        \
        const char *___act = actual;                                    \