selftests/bpf: Add CO-RE relo test for TYPE_ID_LOCAL/TYPE_ID_TARGET

Add tests for BTF type ID relocations. To allow testing this, enhance
core_relo.c test runner to allow dynamic initialization of test inputs.
If Clang doesn't have necessary support for new functionality, test is
skipped.

Signed-off-by: Andrii Nakryiko <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Acked-by: Yonghong Song <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/testing/selftests/bpf/prog_tests/core_reloc.c

···
 #include "progs/core_reloc_types.h"
 #include <sys/mman.h>
 #include <sys/syscall.h>
+#include <bpf/btf.h>
+
+static int duration = 0;
 
 #define STRUCT_TO_CHAR_PTR(struct_name) (const char *)&(struct struct_name)
 
···
 	.fails = true,							\
 }
 
+#define TYPE_ID_CASE_COMMON(name)					\
+	.case_name = #name,						\
+	.bpf_obj_file = "test_core_reloc_type_id.o",			\
+	.btf_src_file = "btf__core_reloc_" #name ".o"			\
+
+#define TYPE_ID_CASE(name, setup_fn) {					\
+	TYPE_ID_CASE_COMMON(name),					\
+	.output = STRUCT_TO_CHAR_PTR(core_reloc_type_id_output) {},	\
+	.output_len = sizeof(struct core_reloc_type_id_output),		\
+	.setup = setup_fn,						\
+}
+
+#define TYPE_ID_ERR_CASE(name) {					\
+	TYPE_ID_CASE_COMMON(name),					\
+	.fails = true,							\
+}
+
+struct core_reloc_test_case;
+
+typedef int (*setup_test_fn)(struct core_reloc_test_case *test);
+
 struct core_reloc_test_case {
 	const char *case_name;
 	const char *bpf_obj_file;
···
 	bool fails;
 	bool relaxed_core_relocs;
 	bool direct_raw_tp;
+	setup_test_fn setup;
 };
+
+static int find_btf_type(const struct btf *btf, const char *name, __u32 kind)
+{
+	int id;
+
+	id = btf__find_by_name_kind(btf, name, kind);
+	if (CHECK(id <= 0, "find_type_id", "failed to find '%s', kind %d: %d\n", name, kind, id))
+		return -1;
+
+	return id;
+}
+
+static int setup_type_id_case_local(struct core_reloc_test_case *test)
+{
+	struct core_reloc_type_id_output *exp = (void *)test->output;
+	struct btf *local_btf = btf__parse(test->bpf_obj_file, NULL);
+	struct btf *targ_btf = btf__parse(test->btf_src_file, NULL);
+	const struct btf_type *t;
+	const char *name;
+	int i;
+
+	if (CHECK(IS_ERR(local_btf), "local_btf", "failed: %ld\n", PTR_ERR(local_btf)) ||
+	    CHECK(IS_ERR(targ_btf), "targ_btf", "failed: %ld\n", PTR_ERR(targ_btf))) {
+		btf__free(local_btf);
+		btf__free(targ_btf);
+		return -EINVAL;
+	}
+
+	exp->local_anon_struct = -1;
+	exp->local_anon_union = -1;
+	exp->local_anon_enum = -1;
+	exp->local_anon_func_proto_ptr = -1;
+	exp->local_anon_void_ptr = -1;
+	exp->local_anon_arr = -1;
+
+	for (i = 1; i <= btf__get_nr_types(local_btf); i++)
+	{
+		t = btf__type_by_id(local_btf, i);
+		/* we are interested only in anonymous types */
+		if (t->name_off)
+			continue;
+
+		if (btf_is_struct(t) && btf_vlen(t) &&
+		    (name = btf__name_by_offset(local_btf, btf_members(t)[0].name_off)) &&
+		    strcmp(name, "marker_field") == 0) {
+			exp->local_anon_struct = i;
+		} else if (btf_is_union(t) && btf_vlen(t) &&
+			 (name = btf__name_by_offset(local_btf, btf_members(t)[0].name_off)) &&
+			 strcmp(name, "marker_field") == 0) {
+			exp->local_anon_union = i;
+		} else if (btf_is_enum(t) && btf_vlen(t) &&
+			 (name = btf__name_by_offset(local_btf, btf_enum(t)[0].name_off)) &&
+			 strcmp(name, "MARKER_ENUM_VAL") == 0) {
+			exp->local_anon_enum = i;
+		} else if (btf_is_ptr(t) && (t = btf__type_by_id(local_btf, t->type))) {
+			if (btf_is_func_proto(t) && (t = btf__type_by_id(local_btf, t->type)) &&
+			    btf_is_int(t) && (name = btf__name_by_offset(local_btf, t->name_off)) &&
+			    strcmp(name, "_Bool") == 0) {
+				/* ptr -> func_proto -> _Bool */
+				exp->local_anon_func_proto_ptr = i;
+			} else if (btf_is_void(t)) {
+				/* ptr -> void */
+				exp->local_anon_void_ptr = i;
+			}
+		} else if (btf_is_array(t) && (t = btf__type_by_id(local_btf, btf_array(t)->type)) &&
+			   btf_is_int(t) && (name = btf__name_by_offset(local_btf, t->name_off)) &&
+			   strcmp(name, "_Bool") == 0) {
+			/* _Bool[] */
+			exp->local_anon_arr = i;
+		}
+	}
+
+	exp->local_struct = find_btf_type(local_btf, "a_struct", BTF_KIND_STRUCT);
+	exp->local_union = find_btf_type(local_btf, "a_union", BTF_KIND_UNION);
+	exp->local_enum = find_btf_type(local_btf, "an_enum", BTF_KIND_ENUM);
+	exp->local_int = find_btf_type(local_btf, "int", BTF_KIND_INT);
+	exp->local_struct_typedef = find_btf_type(local_btf, "named_struct_typedef", BTF_KIND_TYPEDEF);
+	exp->local_func_proto_typedef = find_btf_type(local_btf, "func_proto_typedef", BTF_KIND_TYPEDEF);
+	exp->local_arr_typedef = find_btf_type(local_btf, "arr_typedef", BTF_KIND_TYPEDEF);
+
+	btf__free(local_btf);
+	btf__free(targ_btf);
+	return 0;
+}
+
+static int setup_type_id_case_success(struct core_reloc_test_case *test) {
+	struct core_reloc_type_id_output *exp = (void *)test->output;
+	struct btf *targ_btf = btf__parse(test->btf_src_file, NULL);
+	int err;
+
+	err = setup_type_id_case_local(test);
+	if (err)
+		return err;
+
+	targ_btf = btf__parse(test->btf_src_file, NULL);
+
+	exp->targ_struct = find_btf_type(targ_btf, "a_struct", BTF_KIND_STRUCT);
+	exp->targ_union = find_btf_type(targ_btf, "a_union", BTF_KIND_UNION);
+	exp->targ_enum = find_btf_type(targ_btf, "an_enum", BTF_KIND_ENUM);
+	exp->targ_int = find_btf_type(targ_btf, "int", BTF_KIND_INT);
+	exp->targ_struct_typedef = find_btf_type(targ_btf, "named_struct_typedef", BTF_KIND_TYPEDEF);
+	exp->targ_func_proto_typedef = find_btf_type(targ_btf, "func_proto_typedef", BTF_KIND_TYPEDEF);
+	exp->targ_arr_typedef = find_btf_type(targ_btf, "arr_typedef", BTF_KIND_TYPEDEF);
+
+	btf__free(targ_btf);
+	return 0;
+}
+
+static int setup_type_id_case_failure(struct core_reloc_test_case *test)
+{
+	struct core_reloc_type_id_output *exp = (void *)test->output;
+	int err;
+
+	err = setup_type_id_case_local(test);
+	if (err)
+		return err;
+
+	exp->targ_struct = 0;
+	exp->targ_union = 0;
+	exp->targ_enum = 0;
+	exp->targ_int = 0;
+	exp->targ_struct_typedef = 0;
+	exp->targ_func_proto_typedef = 0;
+	exp->targ_arr_typedef = 0;
+
+	return 0;
+}
 
 static struct core_reloc_test_case test_cases[] = {
 	/* validate we can find kernel image and use its BTF for relocs */
···
 		.struct_exists = 1,
 		.struct_sz = sizeof(struct a_struct),
 	}),
+
+	/* BTF_TYPE_ID_LOCAL/BTF_TYPE_ID_TARGET tests */
+	TYPE_ID_CASE(type_id, setup_type_id_case_success),
+	TYPE_ID_CASE(type_id___missing_targets, setup_type_id_case_failure),
 };
 
 struct data {
···
 	struct bpf_object_load_attr load_attr = {};
 	struct core_reloc_test_case *test_case;
 	const char *tp_name, *probe_name;
-	int err, duration = 0, i, equal;
+	int err, i, equal;
 	struct bpf_link *link = NULL;
 	struct bpf_map *data_map;
 	struct bpf_program *prog;
···
 		if (!test__start_subtest(test_case->case_name))
 			continue;
 
-		DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
-			.relaxed_core_relocs = test_case->relaxed_core_relocs,
-		);
+		if (test_case->setup) {
+			err = test_case->setup(test_case);
+			if (CHECK(err, "test_setup", "test #%d setup failed: %d\n", i, err))
+				continue;
+		}
 
-		obj = bpf_object__open_file(test_case->bpf_obj_file, &opts);
+		obj = bpf_object__open_file(test_case->bpf_obj_file, NULL);
 		if (CHECK(IS_ERR(obj), "obj_open", "failed to open '%s': %ld\n",
 			  test_case->bpf_obj_file, PTR_ERR(obj)))
 			continue;

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

···
+#include "core_reloc_types.h"
+
+void f(struct core_reloc_type_id x) {}

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

···
+#include "core_reloc_types.h"
+
+void f(struct core_reloc_type_id___missing_targets x) {}

tools/testing/selftests/bpf/progs/core_reloc_types.h

···
 	func_proto_typedef___fn_wrong_arg_cnt1 f6;
 	func_proto_typedef___fn_wrong_arg_cnt2 f7;
 };
+
+/*
+ * TYPE ID MAPPING (LOCAL AND TARGET)
+ */
+struct core_reloc_type_id_output {
+	int local_anon_struct;
+	int local_anon_union;
+	int local_anon_enum;
+	int local_anon_func_proto_ptr;
+	int local_anon_void_ptr;
+	int local_anon_arr;
+
+	int local_struct;
+	int local_union;
+	int local_enum;
+	int local_int;
+	int local_struct_typedef;
+	int local_func_proto_typedef;
+	int local_arr_typedef;
+
+	int targ_struct;
+	int targ_union;
+	int targ_enum;
+	int targ_int;
+	int targ_struct_typedef;
+	int targ_func_proto_typedef;
+	int targ_arr_typedef;
+};
+
+struct core_reloc_type_id {
+	struct a_struct f1;
+	union a_union f2;
+	enum an_enum f3;
+	named_struct_typedef f4;
+	func_proto_typedef f5;
+	arr_typedef f6;
+};
+
+struct core_reloc_type_id___missing_targets {
+	/* nothing */
+};

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

···
 
 typedef char arr_typedef[20];
 
-struct core_reloc_type_based {
-	struct a_struct f1;
-	union a_union f2;
-	enum an_enum f3;
-	named_struct_typedef f4;
-	anon_struct_typedef f5;
-	struct_ptr_typedef f6;
-	int_typedef f7;
-	enum_typedef f8;
-	void_ptr_typedef f9;
-	func_proto_typedef f10;
-	arr_typedef f11;
-};
-
 struct core_reloc_type_based_output {
 	bool struct_exists;
 	bool union_exists;

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

···
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_core_read.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+	char in[256];
+	char out[256];
+	bool skip;
+} data = {};
+
+/* some types are shared with test_core_reloc_type_based.c */
+struct a_struct {
+	int x;
+};
+
+union a_union {
+	int y;
+	int z;
+};
+
+enum an_enum {
+	AN_ENUM_VAL1 = 1,
+	AN_ENUM_VAL2 = 2,
+	AN_ENUM_VAL3 = 3,
+};
+
+typedef struct a_struct named_struct_typedef;
+
+typedef int (*func_proto_typedef)(long);
+
+typedef char arr_typedef[20];
+
+struct core_reloc_type_id_output {
+	int local_anon_struct;
+	int local_anon_union;
+	int local_anon_enum;
+	int local_anon_func_proto_ptr;
+	int local_anon_void_ptr;
+	int local_anon_arr;
+
+	int local_struct;
+	int local_union;
+	int local_enum;
+	int local_int;
+	int local_struct_typedef;
+	int local_func_proto_typedef;
+	int local_arr_typedef;
+
+	int targ_struct;
+	int targ_union;
+	int targ_enum;
+	int targ_int;
+	int targ_struct_typedef;
+	int targ_func_proto_typedef;
+	int targ_arr_typedef;
+};
+
+/* preserve types even if Clang doesn't support built-in */
+struct a_struct t1 = {};
+union a_union t2 = {};
+enum an_enum t3 = 0;
+named_struct_typedef t4 = {};
+func_proto_typedef t5 = 0;
+arr_typedef t6 = {};
+
+SEC("raw_tracepoint/sys_enter")
+int test_core_type_id(void *ctx)
+{
+	/* We use __builtin_btf_type_id() in this tests, but up until the time
+	 * __builtin_preserve_type_info() was added it contained a bug that
+	 * would make this test fail. The bug was fixed with addition of
+	 * __builtin_preserve_type_info(), though, so that's what we are using
+	 * to detect whether this test has to be executed, however strange
+	 * that might look like.
+	 */
+#if __has_builtin(__builtin_preserve_type_info)
+	struct core_reloc_type_id_output *out = (void *)&data.out;
+
+	out->local_anon_struct = bpf_core_type_id_local(struct { int marker_field; });
+	out->local_anon_union = bpf_core_type_id_local(union { int marker_field; });
+	out->local_anon_enum = bpf_core_type_id_local(enum { MARKER_ENUM_VAL = 123 });
+	out->local_anon_func_proto_ptr = bpf_core_type_id_local(_Bool(*)(int));
+	out->local_anon_void_ptr = bpf_core_type_id_local(void *);
+	out->local_anon_arr = bpf_core_type_id_local(_Bool[47]);
+
+	out->local_struct = bpf_core_type_id_local(struct a_struct);
+	out->local_union = bpf_core_type_id_local(union a_union);
+	out->local_enum = bpf_core_type_id_local(enum an_enum);
+	out->local_int = bpf_core_type_id_local(int);
+	out->local_struct_typedef = bpf_core_type_id_local(named_struct_typedef);
+	out->local_func_proto_typedef = bpf_core_type_id_local(func_proto_typedef);
+	out->local_arr_typedef = bpf_core_type_id_local(arr_typedef);
+
+	out->targ_struct = bpf_core_type_id_kernel(struct a_struct);
+	out->targ_union = bpf_core_type_id_kernel(union a_union);
+	out->targ_enum = bpf_core_type_id_kernel(enum an_enum);
+	out->targ_int = bpf_core_type_id_kernel(int);
+	out->targ_struct_typedef = bpf_core_type_id_kernel(named_struct_typedef);
+	out->targ_func_proto_typedef = bpf_core_type_id_kernel(func_proto_typedef);
+	out->targ_arr_typedef = bpf_core_type_id_kernel(arr_typedef);
+#else
+	data.skip = true;
+#endif
+
+	return 0;
+}