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Message-Id: <20200828193603.335512-6-sdf@google.com>
Date: Fri, 28 Aug 2020 12:36:00 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: davem@...emloft.net, ast@...nel.org, daniel@...earbox.net,
YiFei Zhu <zhuyifei@...gle.com>,
YiFei Zhu <zhuyifei1999@...il.com>,
Stanislav Fomichev <sdf@...gle.com>
Subject: [PATCH bpf-next v3 5/8] bpftool: support dumping metadata
From: YiFei Zhu <zhuyifei@...gle.com>
Added a flag "--metadata" to `bpftool prog list` to dump the metadata
contents. For some formatting some BTF code is put directly in the
metadata dumping. Sanity checks on the map and the kind of the btf_type
to make sure we are actually dumping what we are expecting.
A helper jsonw_reset is added to json writer so we can reuse the same
json writer without having extraneous commas.
Sample output:
$ bpftool prog --metadata
6: cgroup_skb name prog tag bcf7977d3b93787c gpl
[...]
btf_id 4
metadata:
metadata_a = "foo"
metadata_b = 1
$ bpftool prog --metadata --json --pretty
[{
"id": 6,
[...]
"btf_id": 4,
"metadata": {
"metadata_a": "foo",
"metadata_b": 1
}
}
]
Cc: YiFei Zhu <zhuyifei1999@...il.com>
Signed-off-by: YiFei Zhu <zhuyifei@...gle.com>
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
tools/bpf/bpftool/json_writer.c | 6 ++
tools/bpf/bpftool/json_writer.h | 3 +
tools/bpf/bpftool/main.c | 10 +++
tools/bpf/bpftool/main.h | 1 +
tools/bpf/bpftool/prog.c | 130 ++++++++++++++++++++++++++++++++
5 files changed, 150 insertions(+)
diff --git a/tools/bpf/bpftool/json_writer.c b/tools/bpf/bpftool/json_writer.c
index 86501cd3c763..7fea83bedf48 100644
--- a/tools/bpf/bpftool/json_writer.c
+++ b/tools/bpf/bpftool/json_writer.c
@@ -119,6 +119,12 @@ void jsonw_pretty(json_writer_t *self, bool on)
self->pretty = on;
}
+void jsonw_reset(json_writer_t *self)
+{
+ assert(self->depth == 0);
+ self->sep = '\0';
+}
+
/* Basic blocks */
static void jsonw_begin(json_writer_t *self, int c)
{
diff --git a/tools/bpf/bpftool/json_writer.h b/tools/bpf/bpftool/json_writer.h
index 35cf1f00f96c..8ace65cdb92f 100644
--- a/tools/bpf/bpftool/json_writer.h
+++ b/tools/bpf/bpftool/json_writer.h
@@ -27,6 +27,9 @@ void jsonw_destroy(json_writer_t **self_p);
/* Cause output to have pretty whitespace */
void jsonw_pretty(json_writer_t *self, bool on);
+/* Reset separator to create new JSON */
+void jsonw_reset(json_writer_t *self);
+
/* Add property name */
void jsonw_name(json_writer_t *self, const char *name);
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 4a191fcbeb82..a681d568cfa7 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -28,6 +28,7 @@ bool show_pinned;
bool block_mount;
bool verifier_logs;
bool relaxed_maps;
+bool dump_metadata;
struct pinned_obj_table prog_table;
struct pinned_obj_table map_table;
struct pinned_obj_table link_table;
@@ -351,6 +352,10 @@ static int do_batch(int argc, char **argv)
return err;
}
+enum bpftool_longonly_opts {
+ OPT_METADATA = 256,
+};
+
int main(int argc, char **argv)
{
static const struct option options[] = {
@@ -362,6 +367,7 @@ int main(int argc, char **argv)
{ "mapcompat", no_argument, NULL, 'm' },
{ "nomount", no_argument, NULL, 'n' },
{ "debug", no_argument, NULL, 'd' },
+ { "metadata", no_argument, NULL, OPT_METADATA },
{ 0 }
};
int opt, ret;
@@ -371,6 +377,7 @@ int main(int argc, char **argv)
json_output = false;
show_pinned = false;
block_mount = false;
+ dump_metadata = false;
bin_name = argv[0];
hash_init(prog_table.table);
@@ -412,6 +419,9 @@ int main(int argc, char **argv)
libbpf_set_print(print_all_levels);
verifier_logs = true;
break;
+ case OPT_METADATA:
+ dump_metadata = true;
+ break;
default:
p_err("unrecognized option '%s'", argv[optind - 1]);
if (json_output)
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index c46e52137b87..8750758e9150 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -90,6 +90,7 @@ extern bool show_pids;
extern bool block_mount;
extern bool verifier_logs;
extern bool relaxed_maps;
+extern bool dump_metadata;
extern struct pinned_obj_table prog_table;
extern struct pinned_obj_table map_table;
extern struct pinned_obj_table link_table;
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index d393eb8263a6..5d626c134e7d 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -151,6 +151,130 @@ static void show_prog_maps(int fd, __u32 num_maps)
}
}
+static void show_prog_metadata(int fd, __u32 num_maps)
+{
+ const struct btf_type *t_datasec, *t_var;
+ struct bpf_map_info map_info = {};
+ struct btf_var_secinfo *vsi;
+ struct btf *btf = NULL;
+ unsigned int i, vlen;
+ __u32 map_info_len;
+ void *value = NULL;
+ int key = 0;
+ int map_id;
+ int map_fd;
+ int err;
+
+ if (!num_maps)
+ return;
+
+ map_id = bpf_prog_find_metadata(fd);
+ if (map_id < 0)
+ return;
+
+ map_fd = bpf_map_get_fd_by_id(map_id);
+ if (map_fd < 0) {
+ p_err("can't get map by id (%u): %s", map_id, strerror(errno));
+ return;
+ }
+
+ map_info_len = sizeof(map_info);
+ err = bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len);
+ if (err) {
+ p_err("can't get map info of id (%u): %s", map_id,
+ strerror(errno));
+ goto out_close;
+ }
+
+ value = malloc(map_info.value_size);
+ if (!value) {
+ p_err("mem alloc failed");
+ goto out_close;
+ }
+
+ if (bpf_map_lookup_elem(map_fd, &key, value)) {
+ p_err("metadata map lookup failed: %s", strerror(errno));
+ goto out_free;
+ }
+
+ err = btf__get_from_id(map_info.btf_id, &btf);
+ if (err || !btf) {
+ p_err("metadata BTF get failed: %s", strerror(-err));
+ goto out_free;
+ }
+
+ t_datasec = btf__type_by_id(btf, map_info.btf_value_type_id);
+ if (BTF_INFO_KIND(t_datasec->info) != BTF_KIND_DATASEC) {
+ p_err("bad metadata BTF");
+ goto out_free;
+ }
+
+ vlen = BTF_INFO_VLEN(t_datasec->info);
+ vsi = (struct btf_var_secinfo *)(t_datasec + 1);
+
+ /* We don't proceed to check the kinds of the elements of the DATASEC.
+ * The verifier enforce then to be BTF_KIND_VAR.
+ */
+
+ if (json_output) {
+ struct btf_dumper d = {
+ .btf = btf,
+ .jw = json_wtr,
+ .is_plain_text = false,
+ };
+
+ jsonw_name(json_wtr, "metadata");
+
+ jsonw_start_object(json_wtr);
+ for (i = 0; i < vlen; i++) {
+ t_var = btf__type_by_id(btf, vsi[i].type);
+
+ jsonw_name(json_wtr, btf__name_by_offset(btf, t_var->name_off));
+ err = btf_dumper_type(&d, t_var->type, value + vsi[i].offset);
+ if (err) {
+ p_err("btf dump failed");
+ break;
+ }
+ }
+ jsonw_end_object(json_wtr);
+ } else {
+ json_writer_t *btf_wtr = jsonw_new(stdout);
+ struct btf_dumper d = {
+ .btf = btf,
+ .jw = btf_wtr,
+ .is_plain_text = true,
+ };
+ if (!btf_wtr) {
+ p_err("jsonw alloc failed");
+ goto out_free;
+ }
+
+ printf("\tmetadata:");
+
+ for (i = 0; i < vlen; i++) {
+ t_var = btf__type_by_id(btf, vsi[i].type);
+
+ printf("\n\t\t%s = ", btf__name_by_offset(btf, t_var->name_off));
+
+ jsonw_reset(btf_wtr);
+ err = btf_dumper_type(&d, t_var->type, value + vsi[i].offset);
+ if (err) {
+ p_err("btf dump failed");
+ break;
+ }
+ }
+
+ jsonw_destroy(&btf_wtr);
+ }
+
+out_free:
+ btf__free(btf);
+ free(value);
+
+out_close:
+ close(map_fd);
+}
+
static void print_prog_header_json(struct bpf_prog_info *info)
{
jsonw_uint_field(json_wtr, "id", info->id);
@@ -228,6 +352,9 @@ static void print_prog_json(struct bpf_prog_info *info, int fd)
emit_obj_refs_json(&refs_table, info->id, json_wtr);
+ if (dump_metadata)
+ show_prog_metadata(fd, info->nr_map_ids);
+
jsonw_end_object(json_wtr);
}
@@ -297,6 +424,9 @@ static void print_prog_plain(struct bpf_prog_info *info, int fd)
emit_obj_refs_plain(&refs_table, info->id, "\n\tpids ");
printf("\n");
+
+ if (dump_metadata)
+ show_prog_metadata(fd, info->nr_map_ids);
}
static int show_prog(int fd)
--
2.28.0.402.g5ffc5be6b7-goog
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