selftests: Add test for multiple attachments of freplace program

This adds a selftest for attaching an freplace program to multiple targets
simultaneously.

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

tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c

···
 /* Copyright (c) 2019 Facebook */
 #include <test_progs.h>
 #include <network_helpers.h>
+#include <bpf/btf.h>
+
+typedef int (*test_cb)(struct bpf_object *obj);
+
+static int check_data_map(struct bpf_object *obj, int prog_cnt, bool reset)
+{
+	struct bpf_map *data_map = NULL, *map;
+	__u64 *result = NULL;
+	const int zero = 0;
+	__u32 duration = 0;
+	int ret = -1, i;
+
+	result = malloc((prog_cnt + 32 /* spare */) * sizeof(__u64));
+	if (CHECK(!result, "alloc_memory", "failed to alloc memory"))
+		return -ENOMEM;
+
+	bpf_object__for_each_map(map, obj)
+		if (bpf_map__is_internal(map)) {
+			data_map = map;
+			break;
+		}
+	if (CHECK(!data_map, "find_data_map", "data map not found\n"))
+		goto out;
+
+	ret = bpf_map_lookup_elem(bpf_map__fd(data_map), &zero, result);
+	if (CHECK(ret, "get_result",
+		  "failed to get output data: %d\n", ret))
+		goto out;
+
+	for (i = 0; i < prog_cnt; i++) {
+		if (CHECK(result[i] != 1, "result",
+			  "fexit_bpf2bpf result[%d] failed err %llu\n",
+			  i, result[i]))
+			goto out;
+		result[i] = 0;
+	}
+	if (reset) {
+		ret = bpf_map_update_elem(bpf_map__fd(data_map), &zero, result, 0);
+		if (CHECK(ret, "reset_result", "failed to reset result\n"))
+			goto out;
+	}
+
+	ret = 0;
+out:
+	free(result);
+	return ret;
+}
 
 static void test_fexit_bpf2bpf_common(const char *obj_file,
 				      const char *target_obj_file,
 				      int prog_cnt,
 				      const char **prog_name,
-				      bool run_prog)
+				      bool run_prog,
+				      test_cb cb)
 {
-	struct bpf_object *obj = NULL, *pkt_obj;
-	int err, pkt_fd, i;
-	struct bpf_link **link = NULL;
+	struct bpf_object *obj = NULL, *tgt_obj;
 	struct bpf_program **prog = NULL;
+	struct bpf_link **link = NULL;
 	__u32 duration = 0, retval;
-	struct bpf_map *data_map;
-	const int zero = 0;
-	__u64 *result = NULL;
+	int err, tgt_fd, i;
 
 	err = bpf_prog_load(target_obj_file, BPF_PROG_TYPE_UNSPEC,
-			    &pkt_obj, &pkt_fd);
+			    &tgt_obj, &tgt_fd);
 	if (CHECK(err, "tgt_prog_load", "file %s err %d errno %d\n",
 		  target_obj_file, err, errno))
 		return;
 	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
-			    .attach_prog_fd = pkt_fd,
+			    .attach_prog_fd = tgt_fd,
 			   );
 
 	link = calloc(sizeof(struct bpf_link *), prog_cnt);
 	prog = calloc(sizeof(struct bpf_program *), prog_cnt);
-	result = malloc((prog_cnt + 32 /* spare */) * sizeof(__u64));
-	if (CHECK(!link || !prog || !result, "alloc_memory",
-		  "failed to alloc memory"))
+	if (CHECK(!link || !prog, "alloc_memory", "failed to alloc memory"))
 		goto close_prog;
 
 	obj = bpf_object__open_file(obj_file, &opts);
···
 			goto close_prog;
 	}
 
+	if (cb) {
+		err = cb(obj);
+		if (err)
+			goto close_prog;
+	}
+
 	if (!run_prog)
 		goto close_prog;
 
-	data_map = bpf_object__find_map_by_name(obj, "fexit_bp.bss");
-	if (CHECK(!data_map, "find_data_map", "data map not found\n"))
-		goto close_prog;
-
-	err = bpf_prog_test_run(pkt_fd, 1, &pkt_v6, sizeof(pkt_v6),
+	err = bpf_prog_test_run(tgt_fd, 1, &pkt_v6, sizeof(pkt_v6),
 				NULL, NULL, &retval, &duration);
 	CHECK(err || retval, "ipv6",
 	      "err %d errno %d retval %d duration %d\n",
 	      err, errno, retval, duration);
 
-	err = bpf_map_lookup_elem(bpf_map__fd(data_map), &zero, result);
-	if (CHECK(err, "get_result",
-		  "failed to get output data: %d\n", err))
+	if (check_data_map(obj, prog_cnt, false))
 		goto close_prog;
-
-	for (i = 0; i < prog_cnt; i++)
-		if (CHECK(result[i] != 1, "result", "fexit_bpf2bpf failed err %llu\n",
-			  result[i]))
-			goto close_prog;
 
 close_prog:
 	for (i = 0; i < prog_cnt; i++)
···
 			bpf_link__destroy(link[i]);
 	if (!IS_ERR_OR_NULL(obj))
 		bpf_object__close(obj);
-	bpf_object__close(pkt_obj);
+	bpf_object__close(tgt_obj);
 	free(link);
 	free(prog);
-	free(result);
 }
 
 static void test_target_no_callees(void)
···
 	test_fexit_bpf2bpf_common("./fexit_bpf2bpf_simple.o",
 				  "./test_pkt_md_access.o",
 				  ARRAY_SIZE(prog_name),
-				  prog_name, true);
+				  prog_name, true, NULL);
 }
 
 static void test_target_yes_callees(void)
···
 	test_fexit_bpf2bpf_common("./fexit_bpf2bpf.o",
 				  "./test_pkt_access.o",
 				  ARRAY_SIZE(prog_name),
-				  prog_name, true);
+				  prog_name, true, NULL);
 }
 
 static void test_func_replace(void)
···
 	test_fexit_bpf2bpf_common("./fexit_bpf2bpf.o",
 				  "./test_pkt_access.o",
 				  ARRAY_SIZE(prog_name),
-				  prog_name, true);
+				  prog_name, true, NULL);
 }
 
 static void test_func_replace_verify(void)
···
 	test_fexit_bpf2bpf_common("./freplace_connect4.o",
 				  "./connect4_prog.o",
 				  ARRAY_SIZE(prog_name),
-				  prog_name, false);
+				  prog_name, false, NULL);
+}
+
+static int test_second_attach(struct bpf_object *obj)
+{
+	const char *prog_name = "freplace/get_constant";
+	const char *tgt_name = prog_name + 9; /* cut off freplace/ */
+	const char *tgt_obj_file = "./test_pkt_access.o";
+	struct bpf_program *prog = NULL;
+	struct bpf_object *tgt_obj;
+	__u32 duration = 0, retval;
+	struct bpf_link *link;
+	int err = 0, tgt_fd;
+
+	prog = bpf_object__find_program_by_title(obj, prog_name);
+	if (CHECK(!prog, "find_prog", "prog %s not found\n", prog_name))
+		return -ENOENT;
+
+	err = bpf_prog_load(tgt_obj_file, BPF_PROG_TYPE_UNSPEC,
+			    &tgt_obj, &tgt_fd);
+	if (CHECK(err, "second_prog_load", "file %s err %d errno %d\n",
+		  tgt_obj_file, err, errno))
+		return err;
+
+	link = bpf_program__attach_freplace(prog, tgt_fd, tgt_name);
+	if (CHECK(IS_ERR(link), "second_link", "failed to attach second link prog_fd %d tgt_fd %d\n", bpf_program__fd(prog), tgt_fd))
+		goto out;
+
+	err = bpf_prog_test_run(tgt_fd, 1, &pkt_v6, sizeof(pkt_v6),
+				NULL, NULL, &retval, &duration);
+	if (CHECK(err || retval, "ipv6",
+		  "err %d errno %d retval %d duration %d\n",
+		  err, errno, retval, duration))
+		goto out;
+
+	err = check_data_map(obj, 1, true);
+	if (err)
+		goto out;
+
+out:
+	bpf_link__destroy(link);
+	bpf_object__close(tgt_obj);
+	return err;
+}
+
+static void test_func_replace_multi(void)
+{
+	const char *prog_name[] = {
+		"freplace/get_constant",
+	};
+	test_fexit_bpf2bpf_common("./freplace_get_constant.o",
+				  "./test_pkt_access.o",
+				  ARRAY_SIZE(prog_name),
+				  prog_name, true, test_second_attach);
 }
 
 static void test_func_sockmap_update(void)
···
 	test_fexit_bpf2bpf_common("./freplace_cls_redirect.o",
 				  "./test_cls_redirect.o",
 				  ARRAY_SIZE(prog_name),
-				  prog_name, false);
+				  prog_name, false, NULL);
 }
 
 static void test_obj_load_failure_common(const char *obj_file,
···
 		test_func_replace_return_code();
 	if (test__start_subtest("func_map_prog_compatibility"))
 		test_func_map_prog_compatibility();
+	if (test__start_subtest("func_replace_multi"))
+		test_func_replace_multi();
 }

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

···
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+volatile __u64 test_get_constant = 0;
+SEC("freplace/get_constant")
+int new_get_constant(long val)
+{
+	if (val != 123)
+		return 0;
+	test_get_constant = 1;
+	return test_get_constant; /* original get_constant() returns val - 122 */
+}
+char _license[] SEC("license") = "GPL";