Support encoding of BTF metadata via btf__new_empty_opts().
Current supported opts are base_btf, add_meta and description
for metadata.
Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
tools/lib/bpf/btf.c | 108 +++++++++++++++++++++++++++++++++++++--
tools/lib/bpf/btf.h | 11 ++++
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 117 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 77a072716d58..4b85325336b4 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -122,6 +122,7 @@ struct btf {
bool strs_deduped;
void *meta_data;
+ size_t meta_sz;
/* BTF object FD, if loaded into kernel */
int fd;
@@ -896,8 +897,84 @@ void btf__free(struct btf *btf)
free(btf);
}
-static struct btf *btf_new_empty(struct btf *base_btf)
+static void __btf_add_kind_meta(struct btf *btf, __u8 kind, const char *name,
+ __u16 flags, __u8 info_sz, __u8 elem_sz)
{
+ struct btf_metadata *meta = btf->meta_data;
+ struct btf_kind_meta *kind_meta = &meta->kind_meta[kind];
+
+ kind_meta->name_off = btf__add_str(btf, name);
+ kind_meta->flags = flags;
+ kind_meta->info_sz = info_sz;
+ kind_meta->elem_sz = elem_sz;
+}
+
+#define btf_add_kind_meta(btf, kind, flags, info_sz, elem_sz) \
+ __btf_add_kind_meta(btf, kind, #kind, flags, info_sz, elem_sz)
+
+static int btf_ensure_modifiable(struct btf *btf);
+
+static int btf_add_meta(struct btf *btf, struct btf_new_opts *opts)
+{
+ const char *description = OPTS_GET(opts, description, NULL);
+ struct btf_metadata *meta;
+
+ if (btf_ensure_modifiable(btf))
+ return libbpf_err(-ENOMEM);
+
+ btf->meta_sz = sizeof(struct btf_metadata) +
+ (NR_BTF_KINDS * sizeof(struct btf_kind_meta));
+ btf->meta_data = calloc(1, btf->meta_sz);
+
+ if (!btf->meta_data) {
+ btf->meta_sz = 0;
+ return -ENOMEM;
+ }
+
+ meta = btf->meta_data;
+
+ if (btf->base_btf) {
+ struct btf_metadata *base_meta = btf->base_btf->meta_data;
+
+ if (base_meta && (base_meta->flags & BTF_META_CRC_SET)) {
+ meta->base_crc = base_meta->crc;
+ meta->flags |= BTF_META_BASE_CRC_SET;
+ }
+ }
+
+ if (description)
+ meta->description_off = btf__add_str(btf, description);
+
+ meta->kind_meta_cnt = NR_BTF_KINDS;
+
+ /* all supported kinds should describe their format here. */
+ btf_add_kind_meta(btf, BTF_KIND_UNKN, 0, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_INT, 0, sizeof(__u32), 0);
+ btf_add_kind_meta(btf, BTF_KIND_PTR, 0, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_ARRAY, 0, sizeof(struct btf_array), 0);
+ btf_add_kind_meta(btf, BTF_KIND_STRUCT, 0, 0, sizeof(struct btf_member));
+ btf_add_kind_meta(btf, BTF_KIND_UNION, 0, 0, sizeof(struct btf_member));
+ btf_add_kind_meta(btf, BTF_KIND_ENUM, 0, 0, sizeof(struct btf_enum));
+ btf_add_kind_meta(btf, BTF_KIND_FWD, 0, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_TYPEDEF, 0, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_VOLATILE, 0, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_CONST, 0, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_RESTRICT, 0, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_FUNC, 0, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_FUNC_PROTO, 0, 0, sizeof(struct btf_param));
+ btf_add_kind_meta(btf, BTF_KIND_VAR, 0, sizeof(struct btf_var), 0);
+ btf_add_kind_meta(btf, BTF_KIND_DATASEC, 0, 0, sizeof(struct btf_var_secinfo));
+ btf_add_kind_meta(btf, BTF_KIND_FLOAT, 0, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_DECL_TAG, BTF_KIND_META_OPTIONAL,
+ sizeof(struct btf_decl_tag), 0);
+ btf_add_kind_meta(btf, BTF_KIND_TYPE_TAG, BTF_KIND_META_OPTIONAL, 0, 0);
+ btf_add_kind_meta(btf, BTF_KIND_ENUM64, 0, 0, sizeof(struct btf_enum64));
+ return 0;
+}
+
+static struct btf *btf_new_empty(struct btf_new_opts *opts)
+{
+ struct btf *base_btf = OPTS_GET(opts, base_btf, NULL);
struct btf *btf;
btf = calloc(1, sizeof(*btf));
@@ -934,17 +1011,42 @@ static struct btf *btf_new_empty(struct btf *base_btf)
btf->strs_data = btf->raw_data + btf->hdr->hdr_len;
btf->hdr->str_len = base_btf ? 0 : 1; /* empty string at offset 0 */
+ if (opts->add_meta) {
+ int err = btf_add_meta(btf, opts);
+
+ if (err) {
+ free(btf->raw_data);
+ free(btf);
+ return ERR_PTR(err);
+ }
+ btf->hdr->meta_header.meta_len = btf->meta_sz;
+ }
+
return btf;
}
struct btf *btf__new_empty(void)
{
- return libbpf_ptr(btf_new_empty(NULL));
+ LIBBPF_OPTS(btf_new_opts, opts);
+
+ return libbpf_ptr(btf_new_empty(&opts));
}
struct btf *btf__new_empty_split(struct btf *base_btf)
{
- return libbpf_ptr(btf_new_empty(base_btf));
+ LIBBPF_OPTS(btf_new_opts, opts);
+
+ opts.base_btf = base_btf;
+
+ return libbpf_ptr(btf_new_empty(&opts));
+}
+
+struct btf *btf__new_empty_opts(struct btf_new_opts *opts)
+{
+ if (!OPTS_VALID(opts, btf_new_opts))
+ return libbpf_err_ptr(-EINVAL);
+
+ return libbpf_ptr(btf_new_empty(opts));
}
static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf)
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 8e6880d91c84..6de445225f02 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -107,6 +107,17 @@ LIBBPF_API struct btf *btf__new_empty(void);
*/
LIBBPF_API struct btf *btf__new_empty_split(struct btf *base_btf);
+struct btf_new_opts {
+ size_t sz;
+ struct btf *base_btf; /* optional base BTF */
+ bool add_meta; /* add BTF metadata about encoding */
+ const char *description;/* add description to metadata */
+ size_t :0;
+};
+#define btf_new_opts__last_field description
+
+LIBBPF_API struct btf *btf__new_empty_opts(struct btf_new_opts *opts);
+
LIBBPF_API struct btf *btf__parse(const char *path, struct btf_ext **btf_ext);
LIBBPF_API struct btf *btf__parse_split(const char *path, struct btf *base_btf);
LIBBPF_API struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 7521a2fb7626..edd8be4b21d0 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -395,4 +395,5 @@ LIBBPF_1.2.0 {
LIBBPF_1.3.0 {
global:
bpf_obj_pin_opts;
+ btf__new_empty_opts;
} LIBBPF_1.2.0;
--
2.31.1
