Provide a way to dump BTF metadata info via bpftool; this
consists of BTF size, header fields and kind layout info
(if available); for example
$ bpftool btf dump file vmlinux format meta
size 4966513
magic 0xeb9f
version 1
flags 0x0
hdr_len 24
type_len 2929900
type_off 0
str_len 2036589
str_off 2929900
...or for vmlinux with kind layout, crc:
$ bpftool btf dump file vmlinux format meta
size 5034496
magic 0xeb9f
version 1
flags 0x1
hdr_len 40
type_len 2973628
type_off 0
str_len 2060745
str_off 2973628
kind_layout_len 80
kind_layout_off 5034376
crc 0xb6a5171f
base_crc 0x0
kind 0 flags 0x0 info_sz 0 elem_sz 0
kind 1 flags 0x0 info_sz 4 elem_sz 0
kind 2 flags 0x0 info_sz 0 elem_sz 0
kind 3 flags 0x0 info_sz 12 elem_sz 0
kind 4 flags 0x0 info_sz 0 elem_sz 12
...
JSON output is also supported:
$ bpftool -j btf dump file vmlinux format meta
{"size":4904369,{"header":"magic":60319,"version":1,"flags":0,"hdr_len":24,"type_len":2893508,"type_off":0,"str_len":2010837,"str_off":2893508}}
Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
tools/bpf/bpftool/bash-completion/bpftool | 2 +-
tools/bpf/bpftool/btf.c | 93 ++++++++++++++++++++++-
2 files changed, 92 insertions(+), 3 deletions(-)
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index 085bf18f3659..4c186d4efb35 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -937,7 +937,7 @@ _bpftool()
return 0
;;
format)
- COMPREPLY=( $( compgen -W "c raw" -- "$cur" ) )
+ COMPREPLY=( $( compgen -W "c raw meta" -- "$cur" ) )
;;
*)
# emit extra options
diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index 91fcb75babe3..56f40adcc161 100644
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -504,6 +504,90 @@ static int dump_btf_c(const struct btf *btf,
return err;
}
+static int dump_btf_meta(const struct btf *btf)
+{
+ const struct btf_header *hdr;
+ const struct btf_kind_layout *k;
+ const void *data;
+ __u32 data_sz;
+ __u8 i, nr_kinds;
+
+ data = btf__raw_data(btf, &data_sz);
+ if (!data)
+ return -ENOMEM;
+ hdr = data;
+ if (json_output) {
+ jsonw_start_object(json_wtr); /* btf metadata object */
+ jsonw_uint_field(json_wtr, "size", data_sz);
+ jsonw_start_object(json_wtr);
+ jsonw_name(json_wtr, "header");
+ jsonw_uint_field(json_wtr, "magic", hdr->magic);
+ jsonw_uint_field(json_wtr, "version", hdr->version);
+ jsonw_uint_field(json_wtr, "flags", hdr->flags);
+ jsonw_uint_field(json_wtr, "hdr_len", hdr->hdr_len);
+ jsonw_uint_field(json_wtr, "type_len", hdr->type_len);
+ jsonw_uint_field(json_wtr, "type_off", hdr->type_off);
+ jsonw_uint_field(json_wtr, "str_len", hdr->str_len);
+ jsonw_uint_field(json_wtr, "str_off", hdr->str_off);
+ } else {
+ printf("size %-10d\n", data_sz);
+ printf("magic 0x%-10x\nversion %-10d\nflags 0x%-10x\nhdr_len %-10d\n",
+ hdr->magic, hdr->version, hdr->flags, hdr->hdr_len);
+ printf("type_len %-10d\ntype_off %-10d\n", hdr->type_len, hdr->type_off);
+ printf("str_len %-10d\nstr_off %-10d\n", hdr->str_len, hdr->str_off);
+ }
+
+ if (hdr->hdr_len < sizeof(struct btf_header) ||
+ hdr->kind_layout_len == 0 || hdr->kind_layout_len == 0) {
+ if (json_output) {
+ jsonw_end_object(json_wtr); /* header object */
+ jsonw_end_object(json_wtr); /* metadata object */
+ }
+ return 0;
+ }
+
+ if (json_output) {
+ jsonw_uint_field(json_wtr, "kind_layout_len", hdr->kind_layout_len);
+ jsonw_uint_field(json_wtr, "kind_layout_offset", hdr->kind_layout_off);
+ jsonw_uint_field(json_wtr, "crc", hdr->crc);
+ jsonw_uint_field(json_wtr, "base_crc", hdr->base_crc);
+ jsonw_end_object(json_wtr); /* end header object */
+
+ jsonw_start_object(json_wtr);
+ jsonw_name(json_wtr, "kind_layouts");
+ jsonw_start_array(json_wtr);
+ } else {
+ printf("kind_layout_len %-10d\nkind_layout_off %-10d\n",
+ hdr->kind_layout_len, hdr->kind_layout_off);
+ printf("crc 0x%-10x\nbase_crc 0x%-10x\n",
+ hdr->crc, hdr->base_crc);
+ }
+
+ k = (void *)hdr + hdr->hdr_len + hdr->kind_layout_off;
+ nr_kinds = hdr->kind_layout_len / sizeof(*k);
+ for (i = 0; i < nr_kinds; i++) {
+ if (json_output) {
+ jsonw_start_object(json_wtr);
+ jsonw_name(json_wtr, "kind_layout");
+ jsonw_uint_field(json_wtr, "kind", i);
+ jsonw_uint_field(json_wtr, "flags", k[i].flags);
+ jsonw_uint_field(json_wtr, "info_sz", k[i].info_sz);
+ jsonw_uint_field(json_wtr, "elem_sz", k[i].elem_sz);
+ jsonw_end_object(json_wtr);
+ } else {
+ printf("kind %-4d flags 0x%-4x info_sz %-4d elem_sz %-4d\n",
+ i, k[i].flags, k[i].info_sz, k[i].elem_sz);
+ }
+ }
+ if (json_output) {
+ jsonw_end_array(json_wtr);
+ jsonw_end_object(json_wtr); /* end kind layout */
+ jsonw_end_object(json_wtr); /* end metadata object */
+ }
+
+ return 0;
+}
+
static const char sysfs_vmlinux[] = "/sys/kernel/btf/vmlinux";
static struct btf *get_vmlinux_btf_from_sysfs(void)
@@ -553,6 +637,7 @@ static int do_dump(int argc, char **argv)
__u32 root_type_ids[2];
int root_type_cnt = 0;
bool dump_c = false;
+ bool dump_meta = false;
__u32 btf_id = -1;
const char *src;
int fd = -1;
@@ -654,10 +739,12 @@ static int do_dump(int argc, char **argv)
}
if (strcmp(*argv, "c") == 0) {
dump_c = true;
+ } else if (is_prefix(*argv, "meta")) {
+ dump_meta = true;
} else if (strcmp(*argv, "raw") == 0) {
dump_c = false;
} else {
- p_err("unrecognized format specifier: '%s', possible values: raw, c",
+ p_err("unrecognized format specifier: '%s', possible values: raw, c, meta",
*argv);
err = -EINVAL;
goto done;
@@ -692,6 +779,8 @@ static int do_dump(int argc, char **argv)
goto done;
}
err = dump_btf_c(btf, root_type_ids, root_type_cnt);
+ } else if (dump_meta) {
+ err = dump_btf_meta(btf);
} else {
err = dump_btf_raw(btf, root_type_ids, root_type_cnt);
}
@@ -1063,7 +1152,7 @@ static int do_help(int argc, char **argv)
" %1$s %2$s help\n"
"\n"
" BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | value | kv | all}] | file FILE }\n"
- " FORMAT := { raw | c }\n"
+ " FORMAT := { raw | c | meta }\n"
" " HELP_SPEC_MAP "\n"
" " HELP_SPEC_PROGRAM "\n"
" " HELP_SPEC_OPTIONS " |\n"
--
2.39.3
