Commit 129b9c5e authored by Kui-Feng Lee's avatar Kui-Feng Lee Committed by Andrii Nakryiko
Browse files

libbpf: Assign cookies to links in libbpf. 



Add a cookie field to the attributes of bpf_link_create().
Add bpf_program__attach_trace_opts() to attach a cookie to a link.

Signed-off-by: default avatarKui-Feng Lee <kuifeng@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220510205923.3206889-5-kuifeng@fb.com
parent 2fcc8241

tools/lib/bpf/bpf.c

+8 −0
Original line number Diff line number Diff line
@@ -863,6 +863,14 @@ int bpf_link_create(int prog_fd, int target_fd, 
		if (!OPTS_ZEROED(opts, kprobe_multi))

			return libbpf_err(-EINVAL);

		break;

	case BPF_TRACE_FENTRY:

	case BPF_TRACE_FEXIT:

	case BPF_MODIFY_RETURN:

	case BPF_LSM_MAC:

		attr.link_create.tracing.cookie = OPTS_GET(opts, tracing.cookie, 0);

		if (!OPTS_ZEROED(opts, tracing))

			return libbpf_err(-EINVAL);

		break;

	default:

		if (!OPTS_ZEROED(opts, flags))

			return libbpf_err(-EINVAL);

tools/lib/bpf/bpf.h

+3 −0
Original line number Diff line number Diff line
@@ -420,6 +420,9 @@ struct bpf_link_create_opts { 
			const unsigned long *addrs;

			const __u64 *cookies;

		} kprobe_multi;

		struct {

			__u64 cookie;

		} tracing;

	};

	size_t :0;

};

tools/lib/bpf/libbpf.c

+16 −4
Original line number Diff line number Diff line
@@ -11568,12 +11568,17 @@ static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf 
}



/* Common logic for all BPF program types that attach to a btf_id */

static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog)

static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog,

						   const struct bpf_trace_opts *opts)

{

	LIBBPF_OPTS(bpf_link_create_opts, link_opts);

	char errmsg[STRERR_BUFSIZE];

	struct bpf_link *link;

	int prog_fd, pfd;



	if (!OPTS_VALID(opts, bpf_trace_opts))

		return libbpf_err_ptr(-EINVAL);



	prog_fd = bpf_program__fd(prog);

	if (prog_fd < 0) {

		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
@@ -11586,7 +11591,8 @@ static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *pro 
	link->detach = &bpf_link__detach_fd;



	/* libbpf is smart enough to redirect to BPF_RAW_TRACEPOINT_OPEN on old kernels */

	pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), NULL);

	link_opts.tracing.cookie = OPTS_GET(opts, cookie, 0);

	pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), &link_opts);

	if (pfd < 0) {

		pfd = -errno;

		free(link);
@@ -11600,12 +11606,18 @@ static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *pro 


struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)

{

	return bpf_program__attach_btf_id(prog);

	return bpf_program__attach_btf_id(prog, NULL);

}



struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,

						const struct bpf_trace_opts *opts)

{

	return bpf_program__attach_btf_id(prog, opts);

}



struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)

{

	return bpf_program__attach_btf_id(prog);

	return bpf_program__attach_btf_id(prog, NULL);

}



static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link)

tools/lib/bpf/libbpf.h

+12 −0
Original line number Diff line number Diff line
@@ -603,8 +603,20 @@ bpf_program__attach_tracepoint_opts(const struct bpf_program *prog, 
LIBBPF_API struct bpf_link *

bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,

				   const char *tp_name);



struct bpf_trace_opts {

	/* size of this struct, for forward/backward compatibility */

	size_t sz;

	/* custom user-provided value fetchable through bpf_get_attach_cookie() */

	__u64 cookie;

};

#define bpf_trace_opts__last_field cookie



LIBBPF_API struct bpf_link *

bpf_program__attach_trace(const struct bpf_program *prog);

LIBBPF_API struct bpf_link *

bpf_program__attach_trace_opts(const struct bpf_program *prog, const struct bpf_trace_opts *opts);



LIBBPF_API struct bpf_link *

bpf_program__attach_lsm(const struct bpf_program *prog);

LIBBPF_API struct bpf_link *

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -447,6 +447,7 @@ LIBBPF_0.8.0 { 
		bpf_object__destroy_subskeleton;

		bpf_object__open_subskeleton;

		bpf_program__attach_kprobe_multi_opts;

		bpf_program__attach_trace_opts;

		bpf_program__attach_usdt;

		libbpf_register_prog_handler;

		libbpf_unregister_prog_handler;