Provide a way to dump BTF header and metadata info via
bpftool; for example
$ bpftool btf dump file vmliux format meta
BTF: data size 4963656
Header: magic 0xeb9f, version 1, flags 0x0, hdr_len 32
Types: len 2927556, offset 0
Strings: len 2035881, offset 2927556
Metadata header found: len 184, offset 4963440, flags 0x1
Description: 'generated by dwarves v1.25'
CRC 0x6da2a930 ; base CRC 0x0
Kind metadata for 20 kinds:
BTF_KIND_UNKN[ 0] flags 0x0 info_sz 0 elem_sz 0
BTF_KIND_INT[ 1] flags 0x0 info_sz 4 elem_sz 0
BTF_KIND_PTR[ 2] flags 0x0 info_sz 0 elem_sz 0
BTF_KIND_ARRAY[ 3] flags 0x0 info_sz 12 elem_sz 0
BTF_KIND_STRUCT[ 4] flags 0x0 info_sz 0 elem_sz 12
BTF_KIND_UNION[ 5] flags 0x0 info_sz 0 elem_sz 12
BTF_KIND_ENUM[ 6] flags 0x0 info_sz 0 elem_sz 8
BTF_KIND_FWD[ 7] flags 0x0 info_sz 0 elem_sz 0
BTF_KIND_TYPEDEF[ 8] flags 0x0 info_sz 0 elem_sz 0
BTF_KIND_VOLATILE[ 9] flags 0x0 info_sz 0 elem_sz 0
BTF_KIND_CONST[10] flags 0x0 info_sz 0 elem_sz 0
BTF_KIND_RESTRICT[11] flags 0x0 info_sz 0 elem_sz 0
BTF_KIND_FUNC[12] flags 0x0 info_sz 0 elem_sz 0
BTF_KIND_FUNC_PROTO[13] flags 0x0 info_sz 0 elem_sz 8
BTF_KIND_VAR[14] flags 0x0 info_sz 4 elem_sz 0
BTF_KIND_DATASEC[15] flags 0x0 info_sz 0 elem_sz 12
BTF_KIND_FLOAT[16] flags 0x0 info_sz 0 elem_sz 0
BTF_KIND_DECL_TAG[17] flags 0x1 info_sz 4 elem_sz 0
BTF_KIND_TYPE_TAG[18] flags 0x1 info_sz 0 elem_sz 0
BTF_KIND_ENUM64[19] flags 0x0 info_sz 0 elem_sz 12
Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
tools/bpf/bpftool/btf.c | 46 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index 91fcb75babe3..da4257e00ba8 100644
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -504,6 +504,47 @@ 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_metadata *m;
+ const void *data;
+ __u32 data_sz;
+ __u8 i;
+
+ data = btf__raw_data(btf, &data_sz);
+ if (!data)
+ return -ENOMEM;
+ hdr = data;
+ printf("BTF: data size %u\n", data_sz);
+ printf("Header: magic 0x%x, version %d, flags 0x%x, hdr_len %u\n",
+ hdr->magic, hdr->version, hdr->flags, hdr->hdr_len);
+ printf("Types: len %u, offset %u\n", hdr->type_len, hdr->type_off);
+ printf("Strings: len %u, offset %u\n", hdr->str_len, hdr->str_off);
+
+ if (hdr->hdr_len < sizeof(struct btf_header) ||
+ hdr->meta_header.meta_len == 0 ||
+ hdr->meta_header.meta_off == 0)
+ return 0;
+
+ m = (void *)hdr + hdr->hdr_len + hdr->meta_header.meta_off;
+
+ printf("Metadata header found: len %u, offset %u, flags 0x%x\n",
+ hdr->meta_header.meta_len, hdr->meta_header.meta_off, m->flags);
+ if (m->description_off)
+ printf("Description: '%s'\n", btf__name_by_offset(btf, m->description_off));
+ printf("CRC 0x%x ; base CRC 0x%x\n", m->crc, m->base_crc);
+ printf("Kind metadata for %d kinds:\n", m->kind_meta_cnt);
+ for (i = 0; i < m->kind_meta_cnt; i++) {
+ printf("%20s[%2d] flags 0x%-4x info_sz %2d elem_sz %2d\n",
+ btf__name_by_offset(btf, m->kind_meta[i].name_off),
+ i, m->kind_meta[i].flags, m->kind_meta[i].info_sz,
+ m->kind_meta[i].elem_sz);
+ }
+
+ return 0;
+}
+
static const char sysfs_vmlinux[] = "/sys/kernel/btf/vmlinux";
static struct btf *get_vmlinux_btf_from_sysfs(void)
@@ -553,6 +594,7 @@ 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;
@@ -654,6 +696,8 @@ static int do_dump(int argc, char **argv)
}
if (strcmp(*argv, "c") == 0) {
dump_c = true;
+ } else if (strcmp(*argv, "meta") == 0) {
+ dump_meta = true;
} else if (strcmp(*argv, "raw") == 0) {
dump_c = false;
} else {
@@ -692,6 +736,8 @@ 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);
}
--
2.31.1
