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Date: Mon, 16 Mar 2020 11:54:28 +0000
From: Quentin Monnet <quentin@...valent.com>
To: Martin KaFai Lau <kafai@...com>, bpf@...r.kernel.org
Cc: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, kernel-team@...com,
netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next 4/4] bpftool: Add struct_ops support
2020-03-15 17:56 UTC-0700 ~ Martin KaFai Lau <kafai@...com>
> This patch adds struct_ops support to the bpftool.
[...]
> Signed-off-by: Martin KaFai Lau <kafai@...com>
> ---
> .../Documentation/bpftool-struct_ops.rst | 106 ++++
> tools/bpf/bpftool/bash-completion/bpftool | 28 +
> tools/bpf/bpftool/main.c | 3 +-
> tools/bpf/bpftool/main.h | 1 +
> tools/bpf/bpftool/struct_ops.c | 595 ++++++++++++++++++
> 5 files changed, 732 insertions(+), 1 deletion(-)
> create mode 100644 tools/bpf/bpftool/Documentation/bpftool-struct_ops.rst
> create mode 100644 tools/bpf/bpftool/struct_ops.c
>
> diff --git a/tools/bpf/bpftool/Documentation/bpftool-struct_ops.rst b/tools/bpf/bpftool/Documentation/bpftool-struct_ops.rst
> new file mode 100644
> index 000000000000..27aae5bc632e
> --- /dev/null
> +++ b/tools/bpf/bpftool/Documentation/bpftool-struct_ops.rst
> @@ -0,0 +1,106 @@
> +==================
> +bpftool-struct_ops
> +==================
> +-------------------------------------------------------------------------------
> +tool to register/unregister/introspect BPF struct_ops
> +-------------------------------------------------------------------------------
> +
> +:Manual section: 8
> +
> +SYNOPSIS
> +========
> +
> + **bpftool** [*OPTIONS*] **struct_ops** *COMMAND*
> +
> + *OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] }
> +
> + *COMMANDS* :=
> + { **show** | **list** | **dump** | **register** | **unregister** | **help** }
> +
> +STRUCT_OPS COMMANDS
> +===================
> +
> +| **bpftool** **struct_ops { show | list }** [*STRUCT_OPS_MAP*]
> +| **bpftool** **struct_ops dump** [*STRUCT_OPS_MAP*]
> +| **bpftool** **struct_ops register** *OBJ*
> +| **bpftool** **struct_ops unregister** *STRUCT_OPS_MAP*
> +| **bpftool** **struct_ops help**
> +|
> +| *STRUCT_OPS_MAP* := { **id** *STRUCT_OPS_MAP_ID* | **name** *STRUCT_OPS_MAP_NAME* }
> +| *OBJ* := /a/file/of/bpf_struct_ops.o
> +
> +
> +DESCRIPTION
> +===========
> + **bpftool struct_ops { show | list }** [*STRUCT_OPS_MAP*]
> + Show brief information about the struct_ops in the system.
> + If *STRUCT_OPS_MAP* is specified, it shows information only
> + for the given struct_ops. Otherwise, it lists all struct_ops
> + currently exists in the system.
Typo: s/exists/existing/
> +
> + Output will start with struct_ops map ID, followed by its map
> + name and its struct_ops's kernel type.
> +
> + **bpftool struct_ops dump** [*STRUCT_OPS_MAP*]
> + Dump details information about the struct_ops in the system.
> + If *STRUCT_OPS_MAP* is specified, it dumps information only
> + for the given struct_ops. Otherwise, it dumps all struct_ops
> + currently exists in the system.
Same here.
> +
> + **bpftool struct_ops register** *OBJ*
> + Register bpf struct_ops from *OBJ*. All struct_ops under
> + the ELF section ".struct_ops" will be registered to
> + its kernel subsystem.
> +
> + **bpftool struct_ops unregister** *STRUCT_OPS_MAP*
> + Unregister the *STRUCT_OPS_MAP* from the kernel subsystem.
> +
> + **bpftool struct_ops 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**).
> +
> + -j, --json
> + Generate JSON output. For commands that cannot produce JSON, this
> + option has no effect.
> +
> + -p, --pretty
> + Generate human-readable JSON output. Implies **-j**.
> +
> + -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 struct_ops show**
> +
> +::
> +
> + 100: dctcp tcp_congestion_ops
> + 105: cubic tcp_congestion_ops
> +
> +**# bpftool struct_ops unregister id 105**
> +
> +::
> +
> + Unregistered tcp_congestion_ops cubic id 105
> +
> +**# bpftool struct_ops register bpf_cubic.o**
> +
> +::
> +
> + Registered tcp_congestion_ops cubic id 110
> +
> +
> +SEE ALSO
> +========
> + **bpftool-map**\ (8)
> + **bpftool-prog**\ (8)
Other man pages link to all available bpftool-* pages. If you do not
want to do that, could you at least link to bpf(2) and bpftool(8) please?
[...]
> diff --git a/tools/bpf/bpftool/struct_ops.c b/tools/bpf/bpftool/struct_ops.c
> new file mode 100644
> index 000000000000..ba145e3d0d5d
> --- /dev/null
> +++ b/tools/bpf/bpftool/struct_ops.c
> @@ -0,0 +1,595 @@
> +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +/* Copyright (C) 2020 Facebook */
> +
> +#include <unistd.h>
> +#include <stdio.h>
> +#include <errno.h>
> +
> +#include <linux/err.h>
Nit: line break here, please
> +#include <bpf/libbpf.h>
> +#include <bpf/bpf.h>
> +#include <bpf/btf.h>
Nit again: Could you please have the includes in each block ordered
alphabetically?
> +
> +#include "json_writer.h"
> +#include "main.h"
> +
> +#define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
> +
[...]
> +static struct bpf_map_info *map_info_alloc(__u32 *alloc_len)
> +{
> + struct bpf_map_info *info;
> +
> + if (get_map_info_type_id() < 0)
> + return NULL;
> +
> + info = calloc(1, map_info_alloc_len);
> + if (!info)
> + p_err("mem alloc failed");
> + else
> + *alloc_len = map_info_alloc_len;
> +
> + return info;
> +}
> +
> +/* It iterates all struct_ops maps of the system.
> + * It returns the fd in "*res_fd" and map_info in "*info".
> + * In the very first iteration, info->id should be 0.
> + * An optional map "*name" filter can be specified.
> + * The filter can be made more flexibile in the future.
Typo: flexible
> + * e.g. filter by kernel-struct-ops-name, regex-name, glob-name, ...etc.
> + *
> + * Return value:
> + * 1: A struct_ops map found. It is returned in "*res_fd" and "*info".
> + * The caller can continue to call get_next in the future.
> + * 0: No struct_ops map is returned.
> + * All struct_ops map has been found.
> + * -1: Error and the caller should abort the iteration.
> + */
> +static int get_next_struct_ops_map(const char *name, int *res_fd,
> + struct bpf_map_info *info, __u32 info_len)
> +{
> + __u32 id = info->id;
> + int err, fd;
> +
> + while (true) {
> + err = bpf_map_get_next_id(id, &id);
> + if (err) {
> + if (errno == ENOENT)
> + return 0;
> + p_err("can't get next map %s", strerror(errno));
Nit: Add a colon before "%s"?
> + return -1;
> + }
> +
> + fd = bpf_map_get_fd_by_id(id);
> + if (fd < 0) {
> + if (errno == ENOENT)
> + continue;
> + p_err("can't get map by id (%u): %s",
> + id, strerror(errno));
> + return -1;
> + }
> +
> + err = bpf_obj_get_info_by_fd(fd, info, &info_len);
> + if (err) {
> + p_err("can't get map info: %s", strerror(errno));
> + close(fd);
> + return -1;
> + }
> +
> + if (info->type == BPF_MAP_TYPE_STRUCT_OPS &&
> + (!name || !strcmp(name, info->name))) {
> + *res_fd = fd;
> + return 1;
> + }
> + close(fd);
> + }
> +}
[...]
> +static int do_unregister(int argc, char **argv)
> +{
> + const char *search_type, *search_term;
> + struct res res;
> +
> + if (argc != 2)
> + usage();
Or you could reuse the macros in main.h, for more consistency with other
subcommands:
if (!REQ_ARGS(2))
return -1;
> +
> + search_type = argv[0];
> + search_term = argv[1];
search_type = GET_ARG();
search_term = GET_ARG();
> +
> + res = do_work_on_struct_ops(search_type, search_term,
> + __do_unregister, NULL, NULL);
> +
> + return cmd_retval(&res, true);
> +}
> +
> +static int do_register(int argc, char **argv)
> +{
> + const struct bpf_map_def *def;
> + struct bpf_map_info info = {};
> + __u32 info_len = sizeof(info);
> + int nr_errs = 0, nr_maps = 0;
> + struct bpf_object *obj;
> + struct bpf_link *link;
> + struct bpf_map *map;
> + const char *file;
> +
> + if (argc != 1)
> + usage();
(Same remark here.)
> +
> + file = argv[0];
> +
> + obj = bpf_object__open(file);
> + if (IS_ERR_OR_NULL(obj))
> + return -1;
[...]
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