Commit 0232b788 authored by Kui-Feng Lee's avatar Kui-Feng Lee Committed by Alexei Starovoitov
Browse files

bpftool: Register struct_ops with a link. 



You can include an optional path after specifying the object name for the
'struct_ops register' subcommand.

Since the commit 226bc6ae ("Merge branch 'Transit between BPF TCP
congestion controls.'") has been accepted, it is now possible to create a
link for a struct_ops. This can be done by defining a struct_ops in
SEC(".struct_ops.link") to make libbpf returns a real link. If we don't pin
the links before leaving bpftool, they will disappear. To instruct bpftool
to pin the links in a directory with the names of the maps, we need to
provide the path of that directory.

Signed-off-by: default avatarKui-Feng Lee <kuifeng@meta.com>
Reviewed-by: default avatarQuentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/20230420002822.345222-1-kuifeng@meta.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 833d67ec

tools/bpf/bpftool/common.c

+14 −0
Original line number Diff line number Diff line
@@ -1091,3 +1091,17 @@ const char *bpf_attach_type_input_str(enum bpf_attach_type t) 
	default:	return libbpf_bpf_attach_type_str(t);

	}

}



int pathname_concat(char *buf, int buf_sz, const char *path,

		    const char *name)

{

	int len;



	len = snprintf(buf, buf_sz, "%s/%s", path, name);

	if (len < 0)

		return -EINVAL;

	if (len >= buf_sz)

		return -ENAMETOOLONG;



	return 0;

}

tools/bpf/bpftool/main.h

+3 −0
Original line number Diff line number Diff line
@@ -264,4 +264,7 @@ static inline bool hashmap__empty(struct hashmap *map) 
	return map ? hashmap__size(map) == 0 : true;

}



int pathname_concat(char *buf, int buf_sz, const char *path,

		    const char *name);



#endif

tools/bpf/bpftool/prog.c

+0 −13
Original line number Diff line number Diff line
@@ -1476,19 +1476,6 @@ auto_attach_program(struct bpf_program *prog, const char *path) 
	return err;

}



static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name)

{

	int len;



	len = snprintf(buf, buf_sz, "%s/%s", path, name);

	if (len < 0)

		return -EINVAL;

	if ((size_t)len >= buf_sz)

		return -ENAMETOOLONG;



	return 0;

}



static int

auto_attach_programs(struct bpf_object *obj, const char *path)

{

tools/bpf/bpftool/struct_ops.c

+58 −12
Original line number Diff line number Diff line
@@ -475,21 +475,44 @@ static int do_unregister(int argc, char **argv) 
	return cmd_retval(&res, true);

}



static int pin_link(struct bpf_link *link, const char *pindir,

		    const char *name)

{

	char pinfile[PATH_MAX];

	int err;



	err = pathname_concat(pinfile, sizeof(pinfile), pindir, name);

	if (err)

		return -1;



	return bpf_link__pin(link, pinfile);

}



static int do_register(int argc, char **argv)

{

	LIBBPF_OPTS(bpf_object_open_opts, open_opts);

	__u32 link_info_len = sizeof(struct bpf_link_info);

	struct bpf_link_info link_info = {};

	struct bpf_map_info info = {};

	__u32 info_len = sizeof(info);

	int nr_errs = 0, nr_maps = 0;

	const char *linkdir = NULL;

	struct bpf_object *obj;

	struct bpf_link *link;

	struct bpf_map *map;

	const char *file;



	if (argc != 1)

	if (argc != 1 && argc != 2)

		usage();



	file = GET_ARG();

	if (argc == 1)

		linkdir = GET_ARG();



	if (linkdir && mount_bpffs_for_pin(linkdir)) {

		p_err("can't mount bpffs for pinning");

		return -1;

	}



	if (verifier_logs)

		/* log_level1 + log_level2 + stats, but not stable UAPI */
@@ -519,21 +542,44 @@ static int do_register(int argc, char **argv) 
		}

		nr_maps++;



		bpf_link__disconnect(link);

		bpf_link__destroy(link);



		if (!bpf_map_get_info_by_fd(bpf_map__fd(map), &info,

					    &info_len))

			p_info("Registered %s %s id %u",

			       get_kern_struct_ops_name(&info),

			       bpf_map__name(map),

			       info.id);

		else

		if (bpf_map_get_info_by_fd(bpf_map__fd(map), &info,

					   &info_len)) {

			/* Not p_err.  The struct_ops was attached

			 * successfully.

			 */

			p_info("Registered %s but can't find id: %s",

			       bpf_map__name(map), strerror(errno));

			goto clean_link;

		}

		if (!(bpf_map__map_flags(map) & BPF_F_LINK)) {

			p_info("Registered %s %s id %u",

			       get_kern_struct_ops_name(&info),

			       info.name,

			       info.id);

			goto clean_link;

		}

		if (bpf_link_get_info_by_fd(bpf_link__fd(link),

					    &link_info,

					    &link_info_len)) {

			p_err("Registered %s but can't find link id: %s",

			      bpf_map__name(map), strerror(errno));

			nr_errs++;

			goto clean_link;

		}

		if (linkdir && pin_link(link, linkdir, info.name)) {

			p_err("can't pin link %u for %s: %s",

			      link_info.id, info.name,

			      strerror(errno));

			nr_errs++;

			goto clean_link;

		}

		p_info("Registered %s %s map id %u link id %u",

		       get_kern_struct_ops_name(&info),

		       info.name, info.id, link_info.id);



clean_link:

		bpf_link__disconnect(link);

		bpf_link__destroy(link);

	}



	bpf_object__close(obj);
@@ -562,7 +608,7 @@ static int do_help(int argc, char **argv) 
	fprintf(stderr,

		"Usage: %1$s %2$s { show | list } [STRUCT_OPS_MAP]\n"

		"       %1$s %2$s dump [STRUCT_OPS_MAP]\n"

		"       %1$s %2$s register OBJ\n"

		"       %1$s %2$s register OBJ [LINK_DIR]\n"

		"       %1$s %2$s unregister STRUCT_OPS_MAP\n"

		"       %1$s %2$s help\n"

		"\n"