Commit 9406b485 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

tools/bpftool: Add bpf_iter support for bptool 



Currently, only one command is supported
  bpftool iter pin <bpf_prog.o> <path>

It will pin the trace/iter bpf program in
the object file <bpf_prog.o> to the <path>
where <path> should be on a bpffs mount.

For example,
  $ bpftool iter pin ./bpf_iter_ipv6_route.o \
    /sys/fs/bpf/my_route
User can then do a `cat` to print out the results:
  $ cat /sys/fs/bpf/my_route
    fe800000000000000000000000000000 40 00000000000000000000000000000000 ...
    00000000000000000000000000000000 00 00000000000000000000000000000000 ...
    00000000000000000000000000000001 80 00000000000000000000000000000000 ...
    fe800000000000008c0162fffebdfd57 80 00000000000000000000000000000000 ...
    ff000000000000000000000000000000 08 00000000000000000000000000000000 ...
    00000000000000000000000000000000 00 00000000000000000000000000000000 ...

The implementation for ipv6_route iterator is in one of subsequent
patches.

This patch also added BPF_LINK_TYPE_ITER to link query.

In the future, we may add additional parameters to pin command
by parameterizing the bpf iterator. For example, a map_id or pid
may be added to let bpf program only traverses a single map or task,
similar to kernel seq_file single_open().

We may also add introspection command for targets/iterators by
leveraging the bpf_iter itself.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200509175920.2477247-1-yhs@fb.com
parent 5fbc2208

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

0 → 100644
+83 −0
Original line number Diff line number Diff line 
============

bpftool-iter

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

-------------------------------------------------------------------------------

tool to create BPF iterators

-------------------------------------------------------------------------------



:Manual section: 8



SYNOPSIS

========



	**bpftool** [*OPTIONS*] **iter** *COMMAND*



	*COMMANDS* := { **pin** | **help** }



ITER COMMANDS

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



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

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

|

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





DESCRIPTION

===========

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

		  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

		  (e.g., one task, one bpf_map, etc.). User space can

		  *read* kernel iterator output through *read()* syscall.



		  The *pin* command creates a bpf iterator from *OBJ*,

		  and pin it to *PATH*. The *PATH* should be located

		  in *bpffs* mount. It must not contain a dot

		  character ('.'), which is reserved for future extensions

		  of *bpffs*.



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



	**bpftool iter help**

		  Print short help message.



OPTIONS

=======

	-h, --help

		  Print short generic help message (similar to **bpftool help**).



	-V, --version

		  Print version number (similar to **bpftool version**).



	-d, --debug

		  Print all logs available, even debug-level information. This

		  includes logs from libbpf as well as from the verifier, when

		  attempting to load programs.



EXAMPLES

========

**# bpftool iter pin bpf_iter_netlink.o /sys/fs/bpf/my_netlink**



::



   Create a file-based bpf iterator from bpf_iter_netlink.o and pin it

   to /sys/fs/bpf/my_netlink





SEE ALSO

========

	**bpf**\ (2),

	**bpf-helpers**\ (7),

	**bpftool**\ (8),

	**bpftool-prog**\ (8),

	**bpftool-map**\ (8),

	**bpftool-link**\ (8),

	**bpftool-cgroup**\ (8),

	**bpftool-feature**\ (8),

	**bpftool-net**\ (8),

	**bpftool-perf**\ (8),

	**bpftool-btf**\ (8)

	**bpftool-gen**\ (8)

	**bpftool-struct_ops**\ (8)

tools/bpf/bpftool/bash-completion/bpftool

+13 −0
Original line number Diff line number Diff line
@@ -610,6 +610,19 @@ _bpftool() 
                    ;;

            esac

            ;;

        iter)

            case $command in

                pin)

                    _filedir

                    return 0

                    ;;

                *)

                    [[ $prev == $object ]] && \

                        COMPREPLY=( $( compgen -W 'pin help' \

                            -- "$cur" ) )

                    ;;

            esac

            ;;

        map)

            local MAP_TYPE='id pinned name'

            case $command in

tools/bpf/bpftool/iter.c

0 → 100644
+88 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)

// Copyright (C) 2020 Facebook



#define _GNU_SOURCE

#include <linux/err.h>

#include <bpf/libbpf.h>



#include "main.h"



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

{

	const char *objfile, *path;

	struct bpf_program *prog;

	struct bpf_object *obj;

	struct bpf_link *link;

	int err;



	if (!REQ_ARGS(2))

		usage();



	objfile = GET_ARG();

	path = GET_ARG();



	obj = bpf_object__open(objfile);

	if (IS_ERR(obj)) {

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

		return -1;

	}



	err = bpf_object__load(obj);

	if (err) {

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

		goto close_obj;

	}



	prog = bpf_program__next(NULL, obj);

	if (!prog) {

		p_err("can't find bpf program in objfile %s", objfile);

		goto close_obj;

	}



	link = bpf_program__attach_iter(prog, NULL);

	if (IS_ERR(link)) {

		err = PTR_ERR(link);

		p_err("attach_iter failed for program %s",

		      bpf_program__name(prog));

		goto close_obj;

	}



	err = mount_bpffs_for_pin(path);

	if (err)

		goto close_link;



	err = bpf_link__pin(link, path);

	if (err) {

		p_err("pin_iter failed for program %s to path %s",

		      bpf_program__name(prog), path);

		goto close_link;

	}



close_link:

	bpf_link__destroy(link);

close_obj:

	bpf_object__close(obj);

	return err;

}



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

{

	fprintf(stderr,

		"Usage: %s %s pin OBJ PATH\n"

		"       %s %s help\n"

		"\n",

		bin_name, argv[-2], bin_name, argv[-2]);



	return 0;

}



static const struct cmd cmds[] = {

	{ "help",	do_help },

	{ "pin",	do_pin },

	{ 0 }

};



int do_iter(int argc, char **argv)

{

	return cmd_select(cmds, argc, argv, do_help);

}

tools/bpf/bpftool/link.c

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ static const char * const link_type_name[] = { 
	[BPF_LINK_TYPE_RAW_TRACEPOINT]		= "raw_tracepoint",

	[BPF_LINK_TYPE_TRACING]			= "tracing",

	[BPF_LINK_TYPE_CGROUP]			= "cgroup",

	[BPF_LINK_TYPE_ITER]			= "iter",

};



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

tools/bpf/bpftool/main.c

+2 −1
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ static int do_help(int argc, char **argv) 
		"       %s batch file FILE\n"

		"       %s version\n"

		"\n"

		"       OBJECT := { prog | map | link | cgroup | perf | net | feature | btf | gen | struct_ops }\n"

		"       OBJECT := { prog | map | link | cgroup | perf | net | feature | btf | gen | struct_ops | iter }\n"

		"       " HELP_SPEC_OPTIONS "\n"

		"",

		bin_name, bin_name, bin_name);
@@ -224,6 +224,7 @@ static const struct cmd cmds[] = { 
	{ "btf",	do_btf },

	{ "gen",	do_gen },

	{ "struct_ops",	do_struct_ops },

	{ "iter",	do_iter },

	{ "version",	do_version },

	{ 0 }

};

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