Commit 3140cf12 authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

libbpf: Add bpf_program__attach_uprobe_multi function 



Adding bpf_program__attach_uprobe_multi function that
allows to attach multiple uprobes with uprobe_multi link.

The user can specify uprobes with direct arguments:

  binary_path/func_pattern/pid

or with struct bpf_uprobe_multi_opts opts argument fields:

  const char **syms;
  const unsigned long *offsets;
  const unsigned long *ref_ctr_offsets;
  const __u64 *cookies;

User can specify 2 mutually exclusive set of inputs:

 1) use only path/func_pattern/pid arguments

 2) use path/pid with allowed combinations of:
    syms/offsets/ref_ctr_offsets/cookies/cnt

    - syms and offsets are mutually exclusive
    - ref_ctr_offsets and cookies are optional

Any other usage results in error.

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230809083440.3209381-15-jolsa@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 5054a303

tools/lib/bpf/libbpf.c

+114 −0
Original line number Diff line number Diff line
@@ -11146,6 +11146,120 @@ static int resolve_full_path(const char *file, char *result, size_t result_sz) 
	return -ENOENT;

}



struct bpf_link *

bpf_program__attach_uprobe_multi(const struct bpf_program *prog,

				 pid_t pid,

				 const char *path,

				 const char *func_pattern,

				 const struct bpf_uprobe_multi_opts *opts)

{

	const unsigned long *ref_ctr_offsets = NULL, *offsets = NULL;

	LIBBPF_OPTS(bpf_link_create_opts, lopts);

	unsigned long *resolved_offsets = NULL;

	int err = 0, link_fd, prog_fd;

	struct bpf_link *link = NULL;

	char errmsg[STRERR_BUFSIZE];

	char full_path[PATH_MAX];

	const __u64 *cookies;

	const char **syms;

	size_t cnt;



	if (!OPTS_VALID(opts, bpf_uprobe_multi_opts))

		return libbpf_err_ptr(-EINVAL);



	syms = OPTS_GET(opts, syms, NULL);

	offsets = OPTS_GET(opts, offsets, NULL);

	ref_ctr_offsets = OPTS_GET(opts, ref_ctr_offsets, NULL);

	cookies = OPTS_GET(opts, cookies, NULL);

	cnt = OPTS_GET(opts, cnt, 0);



	/*

	 * User can specify 2 mutually exclusive set of inputs:

	 *

	 * 1) use only path/func_pattern/pid arguments

	 *

	 * 2) use path/pid with allowed combinations of:

	 *    syms/offsets/ref_ctr_offsets/cookies/cnt

	 *

	 *    - syms and offsets are mutually exclusive

	 *    - ref_ctr_offsets and cookies are optional

	 *

	 * Any other usage results in error.

	 */



	if (!path)

		return libbpf_err_ptr(-EINVAL);

	if (!func_pattern && cnt == 0)

		return libbpf_err_ptr(-EINVAL);



	if (func_pattern) {

		if (syms || offsets || ref_ctr_offsets || cookies || cnt)

			return libbpf_err_ptr(-EINVAL);

	} else {

		if (!!syms == !!offsets)

			return libbpf_err_ptr(-EINVAL);

	}



	if (func_pattern) {

		if (!strchr(path, '/')) {

			err = resolve_full_path(path, full_path, sizeof(full_path));

			if (err) {

				pr_warn("prog '%s': failed to resolve full path for '%s': %d\n",

					prog->name, path, err);

				return libbpf_err_ptr(err);

			}

			path = full_path;

		}



		err = elf_resolve_pattern_offsets(path, func_pattern,

						  &resolved_offsets, &cnt);

		if (err < 0)

			return libbpf_err_ptr(err);

		offsets = resolved_offsets;

	} else if (syms) {

		err = elf_resolve_syms_offsets(path, cnt, syms, &resolved_offsets);

		if (err < 0)

			return libbpf_err_ptr(err);

		offsets = resolved_offsets;

	}



	lopts.uprobe_multi.path = path;

	lopts.uprobe_multi.offsets = offsets;

	lopts.uprobe_multi.ref_ctr_offsets = ref_ctr_offsets;

	lopts.uprobe_multi.cookies = cookies;

	lopts.uprobe_multi.cnt = cnt;

	lopts.uprobe_multi.flags = OPTS_GET(opts, retprobe, false) ? BPF_F_UPROBE_MULTI_RETURN : 0;



	if (pid == 0)

		pid = getpid();

	if (pid > 0)

		lopts.uprobe_multi.pid = pid;



	link = calloc(1, sizeof(*link));

	if (!link) {

		err = -ENOMEM;

		goto error;

	}

	link->detach = &bpf_link__detach_fd;



	prog_fd = bpf_program__fd(prog);

	link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &lopts);

	if (link_fd < 0) {

		err = -errno;

		pr_warn("prog '%s': failed to attach multi-uprobe: %s\n",

			prog->name, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));

		goto error;

	}

	link->fd = link_fd;

	free(resolved_offsets);

	return link;



error:

	free(resolved_offsets);

	free(link);

	return libbpf_err_ptr(err);

}



LIBBPF_API struct bpf_link *

bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,

				const char *binary_path, size_t func_offset,

tools/lib/bpf/libbpf.h

+51 −0
Original line number Diff line number Diff line
@@ -529,6 +529,57 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, 
				      const char *pattern,

				      const struct bpf_kprobe_multi_opts *opts);



struct bpf_uprobe_multi_opts {

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

	size_t sz;

	/* array of function symbols to attach to */

	const char **syms;

	/* array of function addresses to attach to */

	const unsigned long *offsets;

	/* optional, array of associated ref counter offsets */

	const unsigned long *ref_ctr_offsets;

	/* optional, array of associated BPF cookies */

	const __u64 *cookies;

	/* number of elements in syms/addrs/cookies arrays */

	size_t cnt;

	/* create return uprobes */

	bool retprobe;

	size_t :0;

};



#define bpf_uprobe_multi_opts__last_field retprobe



/**

 * @brief **bpf_program__attach_uprobe_multi()** attaches a BPF program

 * to multiple uprobes with uprobe_multi link.

 *

 * User can specify 2 mutually exclusive set of inputs:

 *

 *   1) use only path/func_pattern/pid arguments

 *

 *   2) use path/pid with allowed combinations of

 *      syms/offsets/ref_ctr_offsets/cookies/cnt

 *

 *      - syms and offsets are mutually exclusive

 *      - ref_ctr_offsets and cookies are optional

 *

 *

 * @param prog BPF program to attach

 * @param pid Process ID to attach the uprobe to, 0 for self (own process),

 * -1 for all processes

 * @param binary_path Path to binary

 * @param func_pattern Regular expression to specify functions to attach

 * BPF program to

 * @param opts Additional options (see **struct bpf_uprobe_multi_opts**)

 * @return 0, on success; negative error code, otherwise

 */

LIBBPF_API struct bpf_link *

bpf_program__attach_uprobe_multi(const struct bpf_program *prog,

				 pid_t pid,

				 const char *binary_path,

				 const char *func_pattern,

				 const struct bpf_uprobe_multi_opts *opts);



struct bpf_ksyscall_opts {

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

	size_t sz;

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -398,4 +398,5 @@ LIBBPF_1.3.0 { 
		bpf_prog_detach_opts;

		bpf_program__attach_netfilter;

		bpf_program__attach_tcx;

		bpf_program__attach_uprobe_multi;

} LIBBPF_1.2.0;