Merge branch 'Improve set_attach_target() and deprecate open_opts.attach_prog_fd'

Andrii Nakryiko says:

====================

This patch set deprecates bpf_object_open_opts.attach_prog_fd (in libbpf 0.7+)
by extending bpf_program__set_attach_target() to support some more flexible
scenarios. Existing fexit_bpf2bpf selftest is updated accordingly to not use
deprecated APIs.

While at it, also deprecate no-op relaxed_core_relocs option (they are always
"relaxed").

Last patch also const-ifies all high-level libbpf attach APIs, as there is no
reason for them to assume bpf_program/bpf_map modifications.

Patch #1 also removes one more unneeded use of find_sec_def(), relying on
prog->sec_def that's set during bpf_object__open() operation, simplifying
upcoming refactoring a little bit more.

All these changes are preparatory patches before SEC() handling refactoring
that will come next.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/lib/bpf/libbpf.h

@@ -83,12 +83,15 @@ struct bpf_object_open_opts {
 	 * Non-relocatable instructions are replaced with invalid ones to
 	 * prevent accidental errors.
 	 * */
+	LIBBPF_DEPRECATED_SINCE(0, 6, "field has no effect")
 	bool relaxed_core_relocs;
 	/* maps that set the 'pinning' attribute in their definition will have
 	 * their pin_path attribute set to a file in this directory, and be
 	 * auto-pinned to that path on load; defaults to "/sys/fs/bpf".
 	 */
 	const char *pin_root_path;
+
+	LIBBPF_DEPRECATED_SINCE(0, 7, "use bpf_program__set_attach_target() on each individual bpf_program")
 	__u32 attach_prog_fd;
 	/* Additional kernel config content that augments and overrides
 	 * system Kconfig for CONFIG_xxx externs.
@@ -243,7 +246,7 @@ LIBBPF_API int bpf_link__detach(struct bpf_link *link);
 LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
 
 LIBBPF_API struct bpf_link *
-bpf_program__attach(struct bpf_program *prog);
+bpf_program__attach(const struct bpf_program *prog);
 
 struct bpf_perf_event_opts {
 	/* size of this struct, for forward/backward compatiblity */
@@ -254,10 +257,10 @@ struct bpf_perf_event_opts {
 #define bpf_perf_event_opts__last_field bpf_cookie
 
 LIBBPF_API struct bpf_link *
-bpf_program__attach_perf_event(struct bpf_program *prog, int pfd);
+bpf_program__attach_perf_event(const struct bpf_program *prog, int pfd);
 
 LIBBPF_API struct bpf_link *
-bpf_program__attach_perf_event_opts(struct bpf_program *prog, int pfd,
+bpf_program__attach_perf_event_opts(const struct bpf_program *prog, int pfd,
 				    const struct bpf_perf_event_opts *opts);
 
 struct bpf_kprobe_opts {
@@ -274,10 +277,10 @@ struct bpf_kprobe_opts {
 #define bpf_kprobe_opts__last_field retprobe
 
 LIBBPF_API struct bpf_link *
-bpf_program__attach_kprobe(struct bpf_program *prog, bool retprobe,
+bpf_program__attach_kprobe(const struct bpf_program *prog, bool retprobe,
 			   const char *func_name);
 LIBBPF_API struct bpf_link *
-bpf_program__attach_kprobe_opts(struct bpf_program *prog,
+bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
                                 const char *func_name,
                                 const struct bpf_kprobe_opts *opts);
 
@@ -297,11 +300,11 @@ struct bpf_uprobe_opts {
 #define bpf_uprobe_opts__last_field retprobe
 
 LIBBPF_API struct bpf_link *
-bpf_program__attach_uprobe(struct bpf_program *prog, bool retprobe,
+bpf_program__attach_uprobe(const struct bpf_program *prog, bool retprobe,
 			   pid_t pid, const char *binary_path,
 			   size_t func_offset);
 LIBBPF_API struct bpf_link *
-bpf_program__attach_uprobe_opts(struct bpf_program *prog, pid_t pid,
+bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
 				const char *binary_path, size_t func_offset,
 				const struct bpf_uprobe_opts *opts);
 
@@ -314,35 +317,35 @@ struct bpf_tracepoint_opts {
 #define bpf_tracepoint_opts__last_field bpf_cookie
 
 LIBBPF_API struct bpf_link *
-bpf_program__attach_tracepoint(struct bpf_program *prog,
+bpf_program__attach_tracepoint(const struct bpf_program *prog,
 			       const char *tp_category,
 			       const char *tp_name);
 LIBBPF_API struct bpf_link *
-bpf_program__attach_tracepoint_opts(struct bpf_program *prog,
+bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
 				    const char *tp_category,
 				    const char *tp_name,
 				    const struct bpf_tracepoint_opts *opts);
 
 LIBBPF_API struct bpf_link *
-bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
+bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
 				   const char *tp_name);
 LIBBPF_API struct bpf_link *
-bpf_program__attach_trace(struct bpf_program *prog);
+bpf_program__attach_trace(const struct bpf_program *prog);
 LIBBPF_API struct bpf_link *
-bpf_program__attach_lsm(struct bpf_program *prog);
+bpf_program__attach_lsm(const struct bpf_program *prog);
 LIBBPF_API struct bpf_link *
-bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd);
+bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd);
 LIBBPF_API struct bpf_link *
-bpf_program__attach_netns(struct bpf_program *prog, int netns_fd);
+bpf_program__attach_netns(const struct bpf_program *prog, int netns_fd);
 LIBBPF_API struct bpf_link *
-bpf_program__attach_xdp(struct bpf_program *prog, int ifindex);
+bpf_program__attach_xdp(const struct bpf_program *prog, int ifindex);
 LIBBPF_API struct bpf_link *
-bpf_program__attach_freplace(struct bpf_program *prog,
+bpf_program__attach_freplace(const struct bpf_program *prog,
 			     int target_fd, const char *attach_func_name);
 
 struct bpf_map;
 
-LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map);
+LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map);
 
 struct bpf_iter_attach_opts {
 	size_t sz; /* size of this struct for forward/backward compatibility */
@@ -352,7 +355,7 @@ struct bpf_iter_attach_opts {
 #define bpf_iter_attach_opts__last_field link_info_len
 
 LIBBPF_API struct bpf_link *
-bpf_program__attach_iter(struct bpf_program *prog,
+bpf_program__attach_iter(const struct bpf_program *prog,
 			 const struct bpf_iter_attach_opts *opts);
 
 struct bpf_insn;

tools/lib/bpf/libbpf_common.h

@@ -35,6 +35,11 @@
 #else
 #define __LIBBPF_MARK_DEPRECATED_0_6(X)
 #endif
+#if __LIBBPF_CURRENT_VERSION_GEQ(0, 7)
+#define __LIBBPF_MARK_DEPRECATED_0_7(X) X
+#else
+#define __LIBBPF_MARK_DEPRECATED_0_7(X)
+#endif
 
 /* Helper macro to declare and initialize libbpf options struct
  *

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

@@ -249,8 +249,7 @@ static int duration = 0;
 #define SIZE_CASE_COMMON(name)						\
 	.case_name = #name,						\
 	.bpf_obj_file = "test_core_reloc_size.o",			\
-	.btf_src_file = "btf__core_reloc_" #name ".o",			\
-	.relaxed_core_relocs = true
+	.btf_src_file = "btf__core_reloc_" #name ".o"
 
 #define SIZE_OUTPUT_DATA(type)						\
 	STRUCT_TO_CHAR_PTR(core_reloc_size_output) {			\

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

@@ -60,7 +60,7 @@ static void test_fexit_bpf2bpf_common(const char *obj_file,
 	struct bpf_object *obj = NULL, *tgt_obj;
 	__u32 retval, tgt_prog_id, info_len;
 	struct bpf_prog_info prog_info = {};
-	struct bpf_program **prog = NULL;
+	struct bpf_program **prog = NULL, *p;
 	struct bpf_link **link = NULL;
 	int err, tgt_fd, i;
 	struct btf *btf;
@@ -69,9 +69,6 @@ static void test_fexit_bpf2bpf_common(const char *obj_file,
 			    &tgt_obj, &tgt_fd);
 	if (!ASSERT_OK(err, "tgt_prog_load"))
 		return;
-	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
-			    .attach_prog_fd = tgt_fd,
-			   );
 
 	info_len = sizeof(prog_info);
 	err = bpf_obj_get_info_by_fd(tgt_fd, &prog_info, &info_len);
@@ -89,10 +86,15 @@ static void test_fexit_bpf2bpf_common(const char *obj_file,
 	if (!ASSERT_OK_PTR(prog, "prog_ptr"))
 		goto close_prog;
 
-	obj = bpf_object__open_file(obj_file, &opts);
+	obj = bpf_object__open_file(obj_file, NULL);
 	if (!ASSERT_OK_PTR(obj, "obj_open"))
 		goto close_prog;
 
+	bpf_object__for_each_program(p, obj) {
+		err = bpf_program__set_attach_target(p, tgt_fd, NULL);
+		ASSERT_OK(err, "set_attach_target");
+	}
+
 	err = bpf_object__load(obj);
 	if (!ASSERT_OK(err, "obj_load"))
 		goto close_prog;
@@ -270,7 +272,7 @@ static void test_fmod_ret_freplace(void)
 	struct bpf_link *freplace_link = NULL;
 	struct bpf_program *prog;
 	__u32 duration = 0;
-	int err, pkt_fd;
+	int err, pkt_fd, attach_prog_fd;
 
 	err = bpf_prog_load(tgt_name, BPF_PROG_TYPE_UNSPEC,
 			    &pkt_obj, &pkt_fd);
@@ -278,26 +280,32 @@ static void test_fmod_ret_freplace(void)
 	if (CHECK(err, "tgt_prog_load", "file %s err %d errno %d\n",
 		  tgt_name, err, errno))
 		return;
-	opts.attach_prog_fd = pkt_fd;
 
-	freplace_obj = bpf_object__open_file(freplace_name, &opts);
+	freplace_obj = bpf_object__open_file(freplace_name, NULL);
 	if (!ASSERT_OK_PTR(freplace_obj, "freplace_obj_open"))
 		goto out;
 
+	prog = bpf_program__next(NULL, freplace_obj);
+	err = bpf_program__set_attach_target(prog, pkt_fd, NULL);
+	ASSERT_OK(err, "freplace__set_attach_target");
+
 	err = bpf_object__load(freplace_obj);
 	if (CHECK(err, "freplace_obj_load", "err %d\n", err))
 		goto out;
 
-	prog = bpf_program__next(NULL, freplace_obj);
 	freplace_link = bpf_program__attach_trace(prog);
 	if (!ASSERT_OK_PTR(freplace_link, "freplace_attach_trace"))
 		goto out;
 
-	opts.attach_prog_fd = bpf_program__fd(prog);
-	fmod_obj = bpf_object__open_file(fmod_ret_name, &opts);
+	fmod_obj = bpf_object__open_file(fmod_ret_name, NULL);
 	if (!ASSERT_OK_PTR(fmod_obj, "fmod_obj_open"))
 		goto out;
 
+	attach_prog_fd = bpf_program__fd(prog);
+	prog = bpf_program__next(NULL, fmod_obj);
+	err = bpf_program__set_attach_target(prog, attach_prog_fd, NULL);
+	ASSERT_OK(err, "fmod_ret_set_attach_target");
+
 	err = bpf_object__load(fmod_obj);
 	if (CHECK(!err, "fmod_obj_load", "loading fmod_ret should fail\n"))
 		goto out;
@@ -322,14 +330,14 @@ static void test_func_sockmap_update(void)
 }
 
 static void test_obj_load_failure_common(const char *obj_file,
-					  const char *target_obj_file)
-
+					 const char *target_obj_file)
 {
 	/*
 	 * standalone test that asserts failure to load freplace prog
 	 * because of invalid return code.
 	 */
 	struct bpf_object *obj = NULL, *pkt_obj;
+	struct bpf_program *prog;
 	int err, pkt_fd;
 	__u32 duration = 0;
 
@@ -339,14 +347,15 @@ static void test_obj_load_failure_common(const char *obj_file,
 	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,
-			   );
 
-	obj = bpf_object__open_file(obj_file, &opts);
+	obj = bpf_object__open_file(obj_file, NULL);
 	if (!ASSERT_OK_PTR(obj, "obj_open"))
 		goto close_prog;
 
+	prog = bpf_program__next(NULL, obj);
+	err = bpf_program__set_attach_target(prog, pkt_fd, NULL);
+	ASSERT_OK(err, "set_attach_target");
+
 	/* It should fail to load the program */
 	err = bpf_object__load(obj);
 	if (CHECK(!err, "bpf_obj_load should fail", "err %d\n", err))