Commit 47faff37 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
Browse files

libbpf: Add bpf_cookie to perf_event, kprobe, uprobe, and tp attach APIs 



Wire through bpf_cookie for all attach APIs that use perf_event_open under the
hood:
  - for kprobes, extend existing bpf_kprobe_opts with bpf_cookie field;
  - for perf_event, uprobe, and tracepoint APIs, add their _opts variants and
    pass bpf_cookie through opts.

For kernel that don't support BPF_LINK_CREATE for perf_events, and thus
bpf_cookie is not supported either, return error and log warning for user.

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-12-andrii@kernel.org
parent 3ec84f4b

tools/lib/bpf/libbpf.c

+65 −13
Original line number Diff line number Diff line
@@ -9014,12 +9014,16 @@ static void bpf_link_perf_dealloc(struct bpf_link *link) 
	free(perf_link);

}



struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd)

struct bpf_link *bpf_program__attach_perf_event_opts(struct bpf_program *prog, int pfd,

						     const struct bpf_perf_event_opts *opts)

{

	char errmsg[STRERR_BUFSIZE];

	struct bpf_link_perf *link;

	int prog_fd, link_fd = -1, err;



	if (!OPTS_VALID(opts, bpf_perf_event_opts))

		return libbpf_err_ptr(-EINVAL);



	if (pfd < 0) {

		pr_warn("prog '%s': invalid perf event FD %d\n",

			prog->name, pfd);
@@ -9040,7 +9044,10 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pf 
	link->perf_event_fd = pfd;



	if (kernel_supports(prog->obj, FEAT_PERF_LINK)) {

		link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, NULL);

		DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_opts,

			.perf_event.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0));



		link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, &link_opts);

		if (link_fd < 0) {

			err = -errno;

			pr_warn("prog '%s': failed to create BPF link for perf_event FD %d: %d (%s)\n",
@@ -9050,6 +9057,12 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pf 
		}

		link->link.fd = link_fd;

	} else {

		if (OPTS_GET(opts, bpf_cookie, 0)) {

			pr_warn("prog '%s': user context value is not supported\n", prog->name);

			err = -EOPNOTSUPP;

			goto err_out;

		}



		if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {

			err = -errno;

			pr_warn("prog '%s': failed to attach to perf_event FD %d: %s\n",
@@ -9076,6 +9089,11 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pf 
	return libbpf_err_ptr(err);

}



struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd)

{

	return bpf_program__attach_perf_event_opts(prog, pfd, NULL);

}



/*

 * this function is expected to parse integer in the range of [0, 2^31-1] from

 * given file using scanf format string fmt. If actual parsed value is
@@ -9184,8 +9202,9 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name, 
struct bpf_link *

bpf_program__attach_kprobe_opts(struct bpf_program *prog,

				const char *func_name,

				struct bpf_kprobe_opts *opts)

				const struct bpf_kprobe_opts *opts)

{

	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);

	char errmsg[STRERR_BUFSIZE];

	struct bpf_link *link;

	unsigned long offset;
@@ -9197,6 +9216,7 @@ bpf_program__attach_kprobe_opts(struct bpf_program *prog, 


	retprobe = OPTS_GET(opts, retprobe, false);

	offset = OPTS_GET(opts, offset, 0);

	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);



	pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,

				    offset, -1 /* pid */);
@@ -9206,7 +9226,7 @@ bpf_program__attach_kprobe_opts(struct bpf_program *prog, 
			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));

		return libbpf_err_ptr(pfd);

	}

	link = bpf_program__attach_perf_event(prog, pfd);

	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);

	err = libbpf_get_error(link);

	if (err) {

		close(pfd);
@@ -9261,14 +9281,22 @@ static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec, 
	return link;

}



struct bpf_link *bpf_program__attach_uprobe(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,

				const char *binary_path, size_t func_offset,

				const struct bpf_uprobe_opts *opts)

{

	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);

	char errmsg[STRERR_BUFSIZE];

	struct bpf_link *link;

	int pfd, err;

	bool retprobe;



	if (!OPTS_VALID(opts, bpf_uprobe_opts))

		return libbpf_err_ptr(-EINVAL);



	retprobe = OPTS_GET(opts, retprobe, false);

	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);



	pfd = perf_event_open_probe(true /* uprobe */, retprobe,

				    binary_path, func_offset, pid);
@@ -9279,7 +9307,7 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog, 
			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));

		return libbpf_err_ptr(pfd);

	}

	link = bpf_program__attach_perf_event(prog, pfd);

	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);

	err = libbpf_get_error(link);

	if (err) {

		close(pfd);
@@ -9292,6 +9320,16 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog, 
	return link;

}



struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,

					    bool retprobe, pid_t pid,

					    const char *binary_path,

					    size_t func_offset)

{

	DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts, .retprobe = retprobe);



	return bpf_program__attach_uprobe_opts(prog, pid, binary_path, func_offset, &opts);

}



static int determine_tracepoint_id(const char *tp_category,

				   const char *tp_name)

{
@@ -9342,14 +9380,21 @@ static int perf_event_open_tracepoint(const char *tp_category, 
	return pfd;

}



struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,

struct bpf_link *bpf_program__attach_tracepoint_opts(struct bpf_program *prog,

						     const char *tp_category,

						const char *tp_name)

						     const char *tp_name,

						     const struct bpf_tracepoint_opts *opts)

{

	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);

	char errmsg[STRERR_BUFSIZE];

	struct bpf_link *link;

	int pfd, err;



	if (!OPTS_VALID(opts, bpf_tracepoint_opts))

		return libbpf_err_ptr(-EINVAL);



	pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);



	pfd = perf_event_open_tracepoint(tp_category, tp_name);

	if (pfd < 0) {

		pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
@@ -9357,7 +9402,7 @@ struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog, 
			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));

		return libbpf_err_ptr(pfd);

	}

	link = bpf_program__attach_perf_event(prog, pfd);

	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);

	err = libbpf_get_error(link);

	if (err) {

		close(pfd);
@@ -9369,6 +9414,13 @@ struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog, 
	return link;

}



struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,

						const char *tp_category,

						const char *tp_name)

{

	return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);

}



static struct bpf_link *attach_tp(const struct bpf_sec_def *sec,

				  struct bpf_program *prog)

{

tools/lib/bpf/libbpf.h

+59 −12
Original line number Diff line number Diff line
@@ -104,17 +104,6 @@ struct bpf_object_open_opts { 
};

#define bpf_object_open_opts__last_field btf_custom_path



struct bpf_kprobe_opts {

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

	size_t sz;

	/* function's offset to install kprobe to */

	unsigned long offset;

	/* kprobe is return probe */

	bool retprobe;

	size_t :0;

};

#define bpf_kprobe_opts__last_field retprobe



LIBBPF_API struct bpf_object *bpf_object__open(const char *path);

LIBBPF_API struct bpf_object *

bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts);
@@ -255,24 +244,82 @@ LIBBPF_API int bpf_link__destroy(struct bpf_link *link); 


LIBBPF_API struct bpf_link *

bpf_program__attach(struct bpf_program *prog);



struct bpf_perf_event_opts {

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

	size_t sz;

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

	__u64 bpf_cookie;

};

#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);



LIBBPF_API struct bpf_link *

bpf_program__attach_perf_event_opts(struct bpf_program *prog, int pfd,

				    const struct bpf_perf_event_opts *opts);



struct bpf_kprobe_opts {

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

	size_t sz;

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

	__u64 bpf_cookie;

	/* function's offset to install kprobe to */

	unsigned long offset;

	/* kprobe is return probe */

	bool retprobe;

	size_t :0;

};

#define bpf_kprobe_opts__last_field retprobe



LIBBPF_API struct bpf_link *

bpf_program__attach_kprobe(struct bpf_program *prog, bool retprobe,

			   const char *func_name);

LIBBPF_API struct bpf_link *

bpf_program__attach_kprobe_opts(struct bpf_program *prog,

                                const char *func_name,

                                struct bpf_kprobe_opts *opts);

                                const struct bpf_kprobe_opts *opts);



struct bpf_uprobe_opts {

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

	size_t sz;

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

	__u64 bpf_cookie;

	/* uprobe is return probe, invoked at function return time */

	bool retprobe;

	size_t :0;

};

#define bpf_uprobe_opts__last_field retprobe



LIBBPF_API struct bpf_link *

bpf_program__attach_uprobe(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,

				const char *binary_path, size_t func_offset,

				const struct bpf_uprobe_opts *opts);



struct bpf_tracepoint_opts {

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

	size_t sz;

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

	__u64 bpf_cookie;

};

#define bpf_tracepoint_opts__last_field bpf_cookie



LIBBPF_API struct bpf_link *

bpf_program__attach_tracepoint(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,

				    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,

				   const char *tp_name);

LIBBPF_API struct bpf_link *

tools/lib/bpf/libbpf.map

+3 −0
Original line number Diff line number Diff line
@@ -374,6 +374,9 @@ LIBBPF_0.5.0 { 
		bpf_map__pin_path;

		bpf_map_lookup_and_delete_elem_flags;

		bpf_program__attach_kprobe_opts;

		bpf_program__attach_perf_event_opts;

		bpf_program__attach_tracepoint_opts;

		bpf_program__attach_uprobe_opts;

		bpf_object__gen_loader;

		btf__load_from_kernel_by_id;

		btf__load_from_kernel_by_id_split;