Commit a5359091 authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Alexei Starovoitov
Browse files

libbpf: Add support for freplace attachment in bpf_link_create 



This adds support for supplying a target btf ID for the bpf_link_create()
operation, and adds a new bpf_program__attach_freplace() high-level API for
attaching freplace functions with a target.

Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/160138355387.48470.18026176785351166890.stgit@toke.dk
parent 43bc2874

tools/lib/bpf/bpf.c

+15 −3
Original line number Diff line number Diff line
@@ -586,19 +586,31 @@ int bpf_link_create(int prog_fd, int target_fd, 
		    enum bpf_attach_type attach_type,

		    const struct bpf_link_create_opts *opts)

{

	__u32 target_btf_id, iter_info_len;

	union bpf_attr attr;



	if (!OPTS_VALID(opts, bpf_link_create_opts))

		return -EINVAL;



	iter_info_len = OPTS_GET(opts, iter_info_len, 0);

	target_btf_id = OPTS_GET(opts, target_btf_id, 0);



	if (iter_info_len && target_btf_id)

		return -EINVAL;



	memset(&attr, 0, sizeof(attr));

	attr.link_create.prog_fd = prog_fd;

	attr.link_create.target_fd = target_fd;

	attr.link_create.attach_type = attach_type;

	attr.link_create.flags = OPTS_GET(opts, flags, 0);



	if (iter_info_len) {

		attr.link_create.iter_info =

			ptr_to_u64(OPTS_GET(opts, iter_info, (void *)0));

	attr.link_create.iter_info_len = OPTS_GET(opts, iter_info_len, 0);

		attr.link_create.iter_info_len = iter_info_len;

	} else if (target_btf_id) {

		attr.link_create.target_btf_id = target_btf_id;

	}



	return sys_bpf(BPF_LINK_CREATE, &attr, sizeof(attr));

}

tools/lib/bpf/bpf.h

+2 −1
Original line number Diff line number Diff line
@@ -174,8 +174,9 @@ struct bpf_link_create_opts { 
	__u32 flags;

	union bpf_iter_link_info *iter_info;

	__u32 iter_info_len;

	__u32 target_btf_id;

};

#define bpf_link_create_opts__last_field iter_info_len

#define bpf_link_create_opts__last_field target_btf_id



LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,

			       enum bpf_attach_type attach_type,

tools/lib/bpf/libbpf.c

+39 −5
Original line number Diff line number Diff line
@@ -9390,9 +9390,11 @@ static struct bpf_link *attach_iter(const struct bpf_sec_def *sec, 
}



static struct bpf_link *

bpf_program__attach_fd(struct bpf_program *prog, int target_fd,

bpf_program__attach_fd(struct bpf_program *prog, int target_fd, int btf_id,

		       const char *target_name)

{

	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,

			    .target_btf_id = btf_id);

	enum bpf_attach_type attach_type;

	char errmsg[STRERR_BUFSIZE];

	struct bpf_link *link;
@@ -9410,7 +9412,7 @@ bpf_program__attach_fd(struct bpf_program *prog, int target_fd, 
	link->detach = &bpf_link__detach_fd;



	attach_type = bpf_program__get_expected_attach_type(prog);

	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, NULL);

	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts);

	if (link_fd < 0) {

		link_fd = -errno;

		free(link);
@@ -9426,19 +9428,51 @@ bpf_program__attach_fd(struct bpf_program *prog, int target_fd, 
struct bpf_link *

bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd)

{

	return bpf_program__attach_fd(prog, cgroup_fd, "cgroup");

	return bpf_program__attach_fd(prog, cgroup_fd, 0, "cgroup");

}



struct bpf_link *

bpf_program__attach_netns(struct bpf_program *prog, int netns_fd)

{

	return bpf_program__attach_fd(prog, netns_fd, "netns");

	return bpf_program__attach_fd(prog, netns_fd, 0, "netns");

}



struct bpf_link *bpf_program__attach_xdp(struct bpf_program *prog, int ifindex)

{

	/* target_fd/target_ifindex use the same field in LINK_CREATE */

	return bpf_program__attach_fd(prog, ifindex, "xdp");

	return bpf_program__attach_fd(prog, ifindex, 0, "xdp");

}



struct bpf_link *bpf_program__attach_freplace(struct bpf_program *prog,

					      int target_fd,

					      const char *attach_func_name)

{

	int btf_id;



	if (!!target_fd != !!attach_func_name) {

		pr_warn("prog '%s': supply none or both of target_fd and attach_func_name\n",

			prog->name);

		return ERR_PTR(-EINVAL);

	}



	if (prog->type != BPF_PROG_TYPE_EXT) {

		pr_warn("prog '%s': only BPF_PROG_TYPE_EXT can attach as freplace",

			prog->name);

		return ERR_PTR(-EINVAL);

	}



	if (target_fd) {

		btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);

		if (btf_id < 0)

			return ERR_PTR(btf_id);



		return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace");

	} else {

		/* no target, so use raw_tracepoint_open for compatibility

		 * with old kernels

		 */

		return bpf_program__attach_trace(prog);

	}

}



struct bpf_link *

tools/lib/bpf/libbpf.h

+3 −0
Original line number Diff line number Diff line
@@ -261,6 +261,9 @@ LIBBPF_API struct bpf_link * 
bpf_program__attach_netns(struct bpf_program *prog, int netns_fd);

LIBBPF_API struct bpf_link *

bpf_program__attach_xdp(struct bpf_program *prog, int ifindex);

LIBBPF_API struct bpf_link *

bpf_program__attach_freplace(struct bpf_program *prog,

			     int target_fd, const char *attach_func_name);



struct bpf_map;

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -304,6 +304,7 @@ LIBBPF_0.2.0 { 
	global:

		bpf_prog_bind_map;

		bpf_prog_test_run_opts;

		bpf_program__attach_freplace;

		bpf_program__section_name;

		btf__add_array;

		btf__add_const;