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Message-ID: <20181220174723.GN20955@mini-arch.hsd1.ca.comcast.net>
Date: Thu, 20 Dec 2018 09:47:23 -0800
From: Stanislav Fomichev <sdf@...ichev.me>
To: Quentin Monnet <quentin.monnet@...ronome.com>
Cc: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
oss-drivers@...ronome.com,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Jesper Dangaard Brouer <brouer@...hat.com>,
Stanislav Fomichev <sdf@...gle.com>
Subject: Re: [RFC PATCH bpf-next v2 5/9] tools: bpftool: add probes for eBPF
map types
On 12/20, Quentin Monnet wrote:
> Add new probes for eBPF map types, to detect what are the ones available
> on the system. Try creating one map of each type, and see if the kernel
> complains.
>
> Sample output:
>
> # bpftool feature probe kernel
> ...
> Scanning eBPF map types...
> eBPF map_type hash is available
> eBPF map_type array is available
> eBPF map_type prog_array is available
> ...
>
> # bpftool --json --pretty feature probe kernel
> {
> ...
> "map_types": {
> "have_hash_map_type": true,
> "have_array_map_type": true,
> "have_prog_array_map_type": true,
> ...
> }
> }
>
> v2:
> - Move probes from bpftool to libbpf.
> - Remove C-style macros output from this patch.
>
> Signed-off-by: Quentin Monnet <quentin.monnet@...ronome.com>
> ---
> tools/bpf/bpftool/feature.c | 26 +++++++++++++++
> tools/bpf/bpftool/main.h | 3 ++
> tools/bpf/bpftool/map.c | 4 ++-
> tools/lib/bpf/libbpf.h | 1 +
> tools/lib/bpf/libbpf.map | 1 +
> tools/lib/bpf/libbpf_probes.c | 59 +++++++++++++++++++++++++++++++++++
> 6 files changed, 93 insertions(+), 1 deletion(-)
>
> diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
> index 3ba0a0a5904c..3c44953ded5a 100644
> --- a/tools/bpf/bpftool/feature.c
> +++ b/tools/bpf/bpftool/feature.c
> @@ -398,6 +398,26 @@ probe_prog_type(enum bpf_prog_type prog_type, int kernel_version,
> print_bool_feature(feat_name, plain_desc, res);
> }
>
> +static void probe_map_type(enum bpf_map_type map_type)
> +{
> + const char *plain_comment = "eBPF map_type ";
> + char feat_name[128], plain_desc[128];
> + size_t maxlen;
> + bool res;
> +
> + res = bpf_probe_map_type(map_type, 0);
> +
> + maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
> + if (strlen(map_type_name[map_type]) > maxlen) {
> + p_info("map type name too long");
> + return;
> + }
> +
> + sprintf(feat_name, "have_%s_map_type", map_type_name[map_type]);
> + sprintf(plain_desc, "%s%s", plain_comment, map_type_name[map_type]);
> + print_bool_feature(feat_name, plain_desc, res);
> +}
> +
> static int do_probe(int argc, char **argv)
> {
> enum probe_component target = COMPONENT_UNSPEC;
> @@ -468,6 +488,12 @@ static int do_probe(int argc, char **argv)
> for (i = BPF_PROG_TYPE_UNSPEC + 1; i < ARRAY_SIZE(prog_type_name); i++)
> probe_prog_type(i, kernel_version, supported_types);
>
> + print_end_then_start_section("map_types",
> + "Scanning eBPF map types...");
> +
> + for (i = BPF_MAP_TYPE_UNSPEC + 1; i < map_type_name_size; i++)
> + probe_map_type(i);
> +
> exit_close_json:
> if (json_output) {
> /* End current "section" of probes */
> diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
> index 5cfc6601de9b..d7dd84d3c660 100644
> --- a/tools/bpf/bpftool/main.h
> +++ b/tools/bpf/bpftool/main.h
> @@ -75,6 +75,9 @@ static const char * const prog_type_name[] = {
> [BPF_PROG_TYPE_FLOW_DISSECTOR] = "flow_dissector",
> };
>
> +extern const char * const map_type_name[];
> +extern const size_t map_type_name_size;
> +
> enum bpf_obj_type {
> BPF_OBJ_UNKNOWN,
> BPF_OBJ_PROG,
> diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
> index 2037e3dc864b..b73985589929 100644
> --- a/tools/bpf/bpftool/map.c
> +++ b/tools/bpf/bpftool/map.c
> @@ -21,7 +21,7 @@
> #include "json_writer.h"
> #include "main.h"
>
> -static const char * const map_type_name[] = {
> +const char * const map_type_name[] = {
> [BPF_MAP_TYPE_UNSPEC] = "unspec",
> [BPF_MAP_TYPE_HASH] = "hash",
> [BPF_MAP_TYPE_ARRAY] = "array",
> @@ -48,6 +48,8 @@ static const char * const map_type_name[] = {
> [BPF_MAP_TYPE_STACK] = "stack",
> };
>
> +const size_t map_type_name_size = ARRAY_SIZE(map_type_name);
> +
> static bool map_is_per_cpu(__u32 type)
> {
> return type == BPF_MAP_TYPE_PERCPU_HASH ||
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index f4bb2764ca9a..202c1ee5c579 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -360,6 +360,7 @@ bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
> */
> LIBBPF_API bool bpf_probe_prog_type(enum bpf_prog_type prog_type,
> int kernel_version, __u32 ifindex);
> +LIBBPF_API bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex);
>
> #ifdef __cplusplus
> } /* extern "C" */
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 6355e4c80a86..c08f4c726e8e 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -56,6 +56,7 @@ LIBBPF_0.0.1 {
> bpf_object__unpin_maps;
> bpf_object__unpin_programs;
> bpf_perf_event_read_simple;
> + bpf_probe_map_type;
> bpf_probe_prog_type;
> bpf_prog_attach;
> bpf_prog_detach;
> diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
> index 2c5e0cdc9f2f..796fe1e66169 100644
> --- a/tools/lib/bpf/libbpf_probes.c
> +++ b/tools/lib/bpf/libbpf_probes.c
> @@ -53,3 +53,62 @@ bool bpf_probe_prog_type(enum bpf_prog_type prog_type, int kernel_version,
>
> return errno != EINVAL && errno != EOPNOTSUPP;
> }
> +
> +bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
> +{
> + int key_size, value_size, max_entries, map_flags;
> + struct bpf_create_map_attr attr = {};
> + int fd = -1, fd_inner;
> +
> + key_size = sizeof(__u32);
> + value_size = sizeof(__u32);
> + max_entries = 1;
> + map_flags = 0;
> +
> + if (map_type == BPF_MAP_TYPE_LPM_TRIE) {
How about using switch here? So it yells and complains when the new item
is added to the bpf_map_type enum.
> + key_size = sizeof(__u64);
> + value_size = sizeof(__u64);
> + map_flags = BPF_F_NO_PREALLOC;
> + } else if (map_type == BPF_MAP_TYPE_STACK_TRACE) {
> + value_size = sizeof(__u64);
> + } else if (map_type == BPF_MAP_TYPE_CGROUP_STORAGE ||
> + map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) {
> + key_size = sizeof(struct bpf_cgroup_storage_key);
> + value_size = sizeof(__u64);
> + max_entries = 0;
> + } else if (map_type == BPF_MAP_TYPE_QUEUE ||
> + map_type == BPF_MAP_TYPE_STACK) {
> + key_size = 0;
> + }
> +
> + if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
> + map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
> + /* TODO: probe for device, once libbpf has a function to create
> + * map-in-map for offload
> + */
> + if (ifindex)
> + return false;
> +
> + fd_inner = bpf_create_map(BPF_MAP_TYPE_HASH,
> + sizeof(__u32), sizeof(__u32), 1, 0);
> + if (fd_inner < 0)
> + return false;
> + fd = bpf_create_map_in_map(map_type, NULL, sizeof(__u32),
> + fd_inner, 1, 0);
> + close(fd_inner);
> + } else {
> + /* Note: No other restriction on map type probes for offload */
> + attr.map_type = map_type;
> + attr.key_size = key_size;
> + attr.value_size = value_size;
> + attr.max_entries = max_entries;
> + attr.map_flags = map_flags;
> + attr.map_ifindex = ifindex;
> +
> + fd = bpf_create_map_xattr(&attr);
> + }
> + if (fd >= 0)
> + close(fd);
> +
> + return fd >= 0;
> +}
> --
> 2.17.1
>
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