Commit d8793aca authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

tools/bpftool: Add bpftool support for bpf map element iterator 



The optional parameter "map MAP" can be added to "bpftool iter"
command to create a bpf iterator for map elements. For example,
  bpftool iter pin ./prog.o /sys/fs/bpf/p1 map id 333

For map element bpf iterator "map MAP" parameter is required.
Otherwise, bpf link creation will return an error.

Quentin Monnet kindly provided bash-completion implementation
for new "map MAP" option.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200723184119.590799-1-yhs@fb.com
parent cd31039a

tools/bpf/bpftool/Documentation/bpftool-iter.rst

+16 −2
Original line number Diff line number Diff line
@@ -17,14 +17,15 @@ SYNOPSIS 
ITER COMMANDS

===================



|	**bpftool** **iter pin** *OBJ* *PATH*

|	**bpftool** **iter pin** *OBJ* *PATH* [**map** *MAP*]

|	**bpftool** **iter help**

|

|	*OBJ* := /a/file/of/bpf_iter_target.o

|	*MAP* := { **id** *MAP_ID* | **pinned** *FILE* }



DESCRIPTION

===========

	**bpftool iter pin** *OBJ* *PATH*

	**bpftool iter pin** *OBJ* *PATH* [**map** *MAP*]

		  A bpf iterator combines a kernel iterating of

		  particular kernel data (e.g., tasks, bpf_maps, etc.)

		  and a bpf program called for each kernel data object
@@ -37,6 +38,12 @@ DESCRIPTION 
		  character ('.'), which is reserved for future extensions

		  of *bpffs*.



		  Map element bpf iterator requires an additional parameter

		  *MAP* so bpf program can iterate over map elements for

		  that map. User can have a bpf program in kernel to run

		  with each map element, do checking, filtering, aggregation,

		  etc. without copying data to user space.



		  User can then *cat PATH* to see the bpf iterator output.



	**bpftool iter help**
@@ -64,6 +71,13 @@ EXAMPLES 
   Create a file-based bpf iterator from bpf_iter_netlink.o and pin it

   to /sys/fs/bpf/my_netlink



**# bpftool iter pin bpf_iter_hashmap.o /sys/fs/bpf/my_hashmap map id 20**



::



   Create a file-based bpf iterator from bpf_iter_hashmap.o and map with

   id 20, and pin it to /sys/fs/bpf/my_hashmap



SEE ALSO

========

	**bpf**\ (2),

tools/bpf/bpftool/bash-completion/bpftool

+17 −1
Original line number Diff line number Diff line
@@ -615,7 +615,23 @@ _bpftool() 
        iter)

            case $command in

                pin)

                    case $prev in

                        $command)

                            _filedir

                            ;;

                        id)

                            _bpftool_get_map_ids

                            ;;

                        name)

                            _bpftool_get_map_names

                            ;;

                        pinned)

                            _filedir

                            ;;

                        *)

                            _bpftool_one_of_list $MAP_TYPE

                            ;;

                    esac

                    return 0

                    ;;

                *)

tools/bpf/bpftool/iter.c

+29 −4
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
// Copyright (C) 2020 Facebook



#define _GNU_SOURCE

#include <unistd.h>

#include <linux/err.h>

#include <bpf/libbpf.h>
@@ -9,11 +10,12 @@ 


static int do_pin(int argc, char **argv)

{

	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, iter_opts);

	const char *objfile, *path;

	struct bpf_program *prog;

	struct bpf_object *obj;

	struct bpf_link *link;

	int err;

	int err = -1, map_fd = -1;



	if (!REQ_ARGS(2))

		usage();
@@ -21,10 +23,26 @@ static int do_pin(int argc, char **argv) 
	objfile = GET_ARG();

	path = GET_ARG();



	/* optional arguments */

	if (argc) {

		if (is_prefix(*argv, "map")) {

			NEXT_ARG();



			if (!REQ_ARGS(2)) {

				p_err("incorrect map spec");

				return -1;

			}



			map_fd = map_parse_fd(&argc, &argv);

			if (map_fd < 0)

				return -1;

		}

	}



	obj = bpf_object__open(objfile);

	if (IS_ERR(obj)) {

		p_err("can't open objfile %s", objfile);

		return -1;

		goto close_map_fd;

	}



	err = bpf_object__load(obj);
@@ -39,7 +57,10 @@ static int do_pin(int argc, char **argv) 
		goto close_obj;

	}



	link = bpf_program__attach_iter(prog, NULL);

	if (map_fd >= 0)

		iter_opts.map_fd = map_fd;



	link = bpf_program__attach_iter(prog, &iter_opts);

	if (IS_ERR(link)) {

		err = PTR_ERR(link);

		p_err("attach_iter failed for program %s",
@@ -62,14 +83,18 @@ static int do_pin(int argc, char **argv) 
	bpf_link__destroy(link);

close_obj:

	bpf_object__close(obj);

close_map_fd:

	if (map_fd >= 0)

		close(map_fd);

	return err;

}



static int do_help(int argc, char **argv)

{

	fprintf(stderr,

		"Usage: %1$s %2$s pin OBJ PATH\n"

		"Usage: %1$s %2$s pin OBJ PATH [map MAP]\n"

		"       %1$s %2$s help\n"

		"       " HELP_SPEC_MAP "\n"

		"",

		bin_name, "iter");