Commit c09add2f authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

tools/libbpf: Add bpf_iter support 



Two new libbpf APIs are added to support bpf_iter:
  - bpf_program__attach_iter
    Given a bpf program and additional parameters, which is
    none now, returns a bpf_link.
  - bpf_iter_create
    syscall level API to create a bpf iterator.

The macro BPF_SEQ_PRINTF are also introduced. The format
looks like:
  BPF_SEQ_PRINTF(seq, "task id %d\n", pid);

This macro can help bpf program writers with
nicer bpf_seq_printf syntax similar to the kernel one.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175917.2476936-1-yhs@fb.com
parent 9c5f8a10

tools/lib/bpf/bpf.c

+10 −0
Original line number Diff line number Diff line
@@ -619,6 +619,16 @@ int bpf_link_update(int link_fd, int new_prog_fd, 
	return sys_bpf(BPF_LINK_UPDATE, &attr, sizeof(attr));

}



int bpf_iter_create(int link_fd)

{

	union bpf_attr attr;



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

	attr.iter_create.link_fd = link_fd;



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

}



int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,

		   __u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt)

{

tools/lib/bpf/bpf.h

+2 −0
Original line number Diff line number Diff line
@@ -187,6 +187,8 @@ struct bpf_link_update_opts { 
LIBBPF_API int bpf_link_update(int link_fd, int new_prog_fd,

			       const struct bpf_link_update_opts *opts);



LIBBPF_API int bpf_iter_create(int link_fd);



struct bpf_prog_test_run_attr {

	int prog_fd;

	int repeat;

tools/lib/bpf/bpf_tracing.h

+16 −0
Original line number Diff line number Diff line
@@ -413,4 +413,20 @@ typeof(name(0)) name(struct pt_regs *ctx) \ 
}									    \

static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)



/*

 * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values

 * in a structure.

 */

#define BPF_SEQ_PRINTF(seq, fmt, args...)				    \

	({								    \

		_Pragma("GCC diagnostic push")				    \

		_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")	    \

		static const char ___fmt[] = fmt;			    \

		unsigned long long ___param[] = { args };		    \

		_Pragma("GCC diagnostic pop")				    \

		int ___ret = bpf_seq_printf(seq, ___fmt, sizeof(___fmt),    \

					    ___param, sizeof(___param));    \

		___ret;							    \

	})



#endif

tools/lib/bpf/libbpf.c

+52 −0
Original line number Diff line number Diff line
@@ -6586,6 +6586,8 @@ static struct bpf_link *attach_trace(const struct bpf_sec_def *sec, 
				     struct bpf_program *prog);

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

				   struct bpf_program *prog);

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

				    struct bpf_program *prog);



static const struct bpf_sec_def section_defs[] = {

	BPF_PROG_SEC("socket",			BPF_PROG_TYPE_SOCKET_FILTER),
@@ -6629,6 +6631,10 @@ static const struct bpf_sec_def section_defs[] = { 
		.is_attach_btf = true,

		.expected_attach_type = BPF_LSM_MAC,

		.attach_fn = attach_lsm),

	SEC_DEF("iter/", TRACING,

		.expected_attach_type = BPF_TRACE_ITER,

		.is_attach_btf = true,

		.attach_fn = attach_iter),

	BPF_PROG_SEC("xdp",			BPF_PROG_TYPE_XDP),

	BPF_PROG_SEC("perf_event",		BPF_PROG_TYPE_PERF_EVENT),

	BPF_PROG_SEC("lwt_in",			BPF_PROG_TYPE_LWT_IN),
@@ -6891,6 +6897,7 @@ invalid_prog: 


#define BTF_TRACE_PREFIX "btf_trace_"

#define BTF_LSM_PREFIX "bpf_lsm_"

#define BTF_ITER_PREFIX "__bpf_iter__"

#define BTF_MAX_NAME_SIZE 128



static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
@@ -6921,6 +6928,9 @@ static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name, 
	else if (attach_type == BPF_LSM_MAC)

		err = find_btf_by_prefix_kind(btf, BTF_LSM_PREFIX, name,

					      BTF_KIND_FUNC);

	else if (attach_type == BPF_TRACE_ITER)

		err = find_btf_by_prefix_kind(btf, BTF_ITER_PREFIX, name,

					      BTF_KIND_FUNC);

	else

		err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
@@ -7848,6 +7858,12 @@ static struct bpf_link *attach_lsm(const struct bpf_sec_def *sec, 
	return bpf_program__attach_lsm(prog);

}



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

				    struct bpf_program *prog)

{

	return bpf_program__attach_iter(prog, NULL);

}



struct bpf_link *

bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd)

{
@@ -7882,6 +7898,42 @@ bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd) 
	return link;

}



struct bpf_link *

bpf_program__attach_iter(struct bpf_program *prog,

			 const struct bpf_iter_attach_opts *opts)

{

	char errmsg[STRERR_BUFSIZE];

	struct bpf_link *link;

	int prog_fd, link_fd;



	if (!OPTS_VALID(opts, bpf_iter_attach_opts))

		return ERR_PTR(-EINVAL);



	prog_fd = bpf_program__fd(prog);

	if (prog_fd < 0) {

		pr_warn("program '%s': can't attach before loaded\n",

			bpf_program__title(prog, false));

		return ERR_PTR(-EINVAL);

	}



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

	if (!link)

		return ERR_PTR(-ENOMEM);

	link->detach = &bpf_link__detach_fd;



	link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_ITER, NULL);

	if (link_fd < 0) {

		link_fd = -errno;

		free(link);

		pr_warn("program '%s': failed to attach to iterator: %s\n",

			bpf_program__title(prog, false),

			libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));

		return ERR_PTR(link_fd);

	}

	link->fd = link_fd;

	return link;

}



struct bpf_link *bpf_program__attach(struct bpf_program *prog)

{

	const struct bpf_sec_def *sec_def;

tools/lib/bpf/libbpf.h

+9 −0
Original line number Diff line number Diff line
@@ -258,6 +258,15 @@ struct bpf_map; 


LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map);



struct bpf_iter_attach_opts {

	size_t sz; /* size of this struct for forward/backward compatibility */

};

#define bpf_iter_attach_opts__last_field sz



LIBBPF_API struct bpf_link *

bpf_program__attach_iter(struct bpf_program *prog,

			 const struct bpf_iter_attach_opts *opts);



struct bpf_insn;



/*

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