Add public APIs to parse BTF from raw data file (e.g.,
/sys/kernel/btf/vmlinux), as well as generic btf__parse(), which will try to
determine correct format, currently either raw or ELF.
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
tools/lib/bpf/btf.c | 114 ++++++++++++++++++++++++++-------------
tools/lib/bpf/btf.h | 5 +-
tools/lib/bpf/libbpf.map | 2 +
3 files changed, 83 insertions(+), 38 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index ded5b29965f9..856b09a04563 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -562,6 +562,83 @@ struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
return btf;
}
+struct btf *btf__parse_raw(const char *path)
+{
+ void *data = NULL;
+ struct btf *btf;
+ FILE *f = NULL;
+ __u16 magic;
+ int err = 0;
+ long sz;
+
+ f = fopen(path, "rb");
+ if (!f) {
+ err = -errno;
+ goto err_out;
+ }
+
+ /* check BTF magic */
+ if (fread(&magic, 1, sizeof(magic), f) < sizeof(magic)) {
+ err = -EIO;
+ goto err_out;
+ }
+ if (magic != BTF_MAGIC) {
+ /* definitely not a raw BTF */
+ err = -EPROTO;
+ goto err_out;
+ }
+
+ /* get file size */
+ if (fseek(f, 0, SEEK_END)) {
+ err = -errno;
+ goto err_out;
+ }
+ sz = ftell(f);
+ if (sz < 0) {
+ err = -errno;
+ goto err_out;
+ }
+ /* rewind to the start */
+ if (fseek(f, 0, SEEK_SET)) {
+ err = -errno;
+ goto err_out;
+ }
+
+ /* pre-alloc memory and read all of BTF data */
+ data = malloc(sz);
+ if (!data) {
+ err = -ENOMEM;
+ goto err_out;
+ }
+ if (fread(data, 1, sz, f) < sz) {
+ err = -EIO;
+ goto err_out;
+ }
+
+ /* finally parse BTF data */
+ btf = btf__new(data, sz);
+
+err_out:
+ free(data);
+ if (f)
+ fclose(f);
+ return err ? ERR_PTR(err) : btf;
+}
+
+struct btf *btf__parse(const char *path, struct btf_ext **btf_ext)
+{
+ struct btf *btf;
+
+ if (btf_ext)
+ *btf_ext = NULL;
+
+ btf = btf__parse_raw(path);
+ if (!IS_ERR(btf) || PTR_ERR(btf) != -EPROTO)
+ return btf;
+
+ return btf__parse_elf(path, btf_ext);
+}
+
static int compare_vsi_off(const void *_a, const void *_b)
{
const struct btf_var_secinfo *a = _a;
@@ -2951,41 +3028,6 @@ static int btf_dedup_remap_types(struct btf_dedup *d)
return 0;
}
-static struct btf *btf_load_raw(const char *path)
-{
- struct btf *btf;
- size_t read_cnt;
- struct stat st;
- void *data;
- FILE *f;
-
- if (stat(path, &st))
- return ERR_PTR(-errno);
-
- data = malloc(st.st_size);
- if (!data)
- return ERR_PTR(-ENOMEM);
-
- f = fopen(path, "rb");
- if (!f) {
- btf = ERR_PTR(-errno);
- goto cleanup;
- }
-
- read_cnt = fread(data, 1, st.st_size, f);
- fclose(f);
- if (read_cnt < st.st_size) {
- btf = ERR_PTR(-EBADF);
- goto cleanup;
- }
-
- btf = btf__new(data, read_cnt);
-
-cleanup:
- free(data);
- return btf;
-}
-
/*
* Probe few well-known locations for vmlinux kernel image and try to load BTF
* data out of it to use for target BTF.
@@ -3021,7 +3063,7 @@ struct btf *libbpf_find_kernel_btf(void)
continue;
if (locations[i].raw_btf)
- btf = btf_load_raw(path);
+ btf = btf__parse_raw(path);
else
btf = btf__parse_elf(path, NULL);
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 491c7b41ffdc..f4a1a1d2b9a3 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -64,8 +64,9 @@ struct btf_ext_header {
LIBBPF_API void btf__free(struct btf *btf);
LIBBPF_API struct btf *btf__new(const void *data, __u32 size);
-LIBBPF_API struct btf *btf__parse_elf(const char *path,
- struct btf_ext **btf_ext);
+LIBBPF_API struct btf *btf__parse(const char *path, struct btf_ext **btf_ext);
+LIBBPF_API struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext);
+LIBBPF_API struct btf *btf__parse_raw(const char *path);
LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf);
LIBBPF_API int btf__load(struct btf *btf);
LIBBPF_API __s32 btf__find_by_name(const struct btf *btf,
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index ca49a6a7e5b2..edf6a38807ea 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -291,5 +291,7 @@ LIBBPF_0.1.0 {
bpf_program__is_sk_lookup;
bpf_program__set_autoload;
bpf_program__set_sk_lookup;
+ btf__parse;
+ btf__parse_raw;
btf__set_fd;
} LIBBPF_0.0.9;
--
2.24.1
