Support encoding of BTF kind layout data and crcs via
btf__new_empty_opts().
Current supported opts are base_btf, add_kind_layout and
add_crc.
Kind layout information is maintained in btf.c in the
kind_layouts[] array; when BTF is created with the
add_kind_layout option it represents the current view
of supported BTF kinds.
Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
tools/lib/bpf/btf.c | 74 ++++++++++++++++++++++++++++++++++++++--
tools/lib/bpf/btf.h | 11 ++++++
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 83 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 007ce6bcad70..ed728d0511a4 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -16,6 +16,7 @@
#include <linux/err.h>
#include <linux/btf.h>
#include <gelf.h>
+#include <zlib.h>
#include "btf.h"
#include "bpf.h"
#include "libbpf.h"
@@ -28,6 +29,35 @@
static struct btf_type btf_void;
+/* Describe how kinds are laid out; some have a singular element following the "struct btf_type",
+ * some have BTF_INFO_VLEN(t->info) elements. Specify sizes for both. Flags are currently unused.
+ * Kind layout can be optionally added to the BTF representation in a dedicated section to
+ * facilitate parsing. New kinds must be added here.
+ */
+struct btf_kind_layout kind_layouts[NR_BTF_KINDS] = {
+/* flags singular element size vlen element(s) size */
+{ 0, 0, 0 }, /* _UNKN */
+{ 0, sizeof(__u32), 0 }, /* _INT */
+{ 0, 0, 0 }, /* _PTR */
+{ 0, sizeof(struct btf_array), 0 }, /* _ARRAY */
+{ 0, 0, sizeof(struct btf_member) }, /* _STRUCT */
+{ 0, 0, sizeof(struct btf_member) }, /* _UNION */
+{ 0, 0, sizeof(struct btf_enum) }, /* _ENUM */
+{ 0, 0, 0 }, /* _FWD */
+{ 0, 0, 0 }, /* _TYPEDEF */
+{ 0, 0, 0 }, /* _VOLATILE */
+{ 0, 0, 0 }, /* _CONST */
+{ 0, 0, 0 }, /* _RESTRICT */
+{ 0, 0, 0 }, /* _FUNC */
+{ 0, 0, sizeof(struct btf_param) }, /* _FUNC_PROTO */
+{ 0, sizeof(struct btf_var), 0 }, /* _VAR */
+{ 0, 0, sizeof(struct btf_var_secinfo) }, /* _DATASEC */
+{ 0, 0, 0 }, /* _FLOAT */
+{ 0, sizeof(struct btf_decl_tag), 0 }, /* _DECL_TAG */
+{ 0, 0, 0 }, /* _TYPE_TAG */
+{ 0, 0, sizeof(struct btf_enum64) }, /* _ENUM64 */
+};
+
struct btf {
/* raw BTF data in native endianness */
void *raw_data;
@@ -1061,8 +1091,9 @@ void btf__free(struct btf *btf)
free(btf);
}
-static struct btf *btf_new_empty(struct btf *base_btf)
+static struct btf *btf_new_empty(struct btf_new_opts *opts)
{
+ struct btf *base_btf = OPTS_GET(opts, base_btf, NULL);
struct btf_header *hdr;
struct btf *btf;
@@ -1104,6 +1135,23 @@ static struct btf *btf_new_empty(struct btf *base_btf)
free(btf);
return ERR_PTR(-ENOMEM);
}
+
+ if (opts->add_kind_layout) {
+ btf->kind_layout = kind_layouts;
+ hdr->kind_layout_len = sizeof(kind_layouts);
+ }
+ if (opts->add_crc) {
+ if (btf->base_btf) {
+ struct btf_header *base_hdr = btf->base_btf->hdr;
+
+ if (base_hdr->hdr_len >= sizeof(struct btf_header) &&
+ base_hdr->flags & BTF_FLAG_CRC_SET) {
+ hdr->base_crc = base_hdr->crc;
+ hdr->flags |= BTF_FLAG_BASE_CRC_SET;
+ }
+ }
+ hdr->flags |= BTF_FLAG_CRC_SET;
+ }
memcpy(btf->hdr, hdr, sizeof(*hdr));
return btf;
@@ -1111,12 +1159,26 @@ static struct btf *btf_new_empty(struct btf *base_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)
@@ -1562,6 +1624,12 @@ static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endi
btf_bswap_kind_layout_sec(p, hdr->kind_layout_len);
}
+ if (hdr->flags & BTF_FLAG_CRC_SET) {
+ struct btf_header *h = data;
+
+ h->crc = crc32(0L, (const Bytef *)data, data_sz);
+ }
+
*size = data_sz;
return data;
err_out:
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 8e6880d91c84..d25bd5c19eec 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_kind_layout; /* add BTF kind layout information */
+ bool add_crc; /* add CRC information */
+ size_t:0;
+};
+#define btf_new_opts__last_field add_crc
+
+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 b52dc28dc8af..b8c0716133d1 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -401,6 +401,7 @@ LIBBPF_1.3.0 {
bpf_program__attach_netkit;
bpf_program__attach_tcx;
bpf_program__attach_uprobe_multi;
+ btf__new_empty_opts;
ring__avail_data_size;
ring__consume;
ring__consumer_pos;
--
2.31.1
