libbpf: Add OPTS-based bpf_btf_load() API
Similar to previous bpf_prog_load() and bpf_map_create() APIs, add
bpf_btf_load() API which is taking optional OPTS struct. Schedule
bpf_load_btf() for deprecation in v0.8 ([0]).
This makes naming consistent with BPF_BTF_LOAD command, sets up an API
for extensibility in the future, moves options parameters (log-related
fields) into optional options, and also allows to pass log_level
directly.
It also removes log buffer auto-allocation logic from low-level API
(consistent with bpf_prog_load() behavior), but preserves a special
treatment of log_level == 0 with non-NULL log_buf, which matches
low-level bpf_prog_load() and high-level libbpf APIs for BTF and program
loading behaviors.
[0] Closes: https://github.com/libbpf/libbpf/issues/419
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-3-andrii@kernel.org
diff --git a/src/bpf.c b/src/bpf.c
index 3dc8634..6b2407e 100644
--- a/src/bpf.c
+++ b/src/bpf.c
@@ -1047,24 +1047,65 @@
return libbpf_err_errno(fd);
}
-int bpf_load_btf(const void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size,
- bool do_log)
+int bpf_btf_load(const void *btf_data, size_t btf_size, const struct bpf_btf_load_opts *opts)
{
- union bpf_attr attr = {};
+ const size_t attr_sz = offsetofend(union bpf_attr, btf_log_level);
+ union bpf_attr attr;
+ char *log_buf;
+ size_t log_size;
+ __u32 log_level;
int fd;
- attr.btf = ptr_to_u64(btf);
+ memset(&attr, 0, attr_sz);
+
+ if (!OPTS_VALID(opts, bpf_btf_load_opts))
+ return libbpf_err(-EINVAL);
+
+ log_buf = OPTS_GET(opts, log_buf, NULL);
+ log_size = OPTS_GET(opts, log_size, 0);
+ log_level = OPTS_GET(opts, log_level, 0);
+
+ if (log_size > UINT_MAX)
+ return libbpf_err(-EINVAL);
+ if (log_size && !log_buf)
+ return libbpf_err(-EINVAL);
+
+ attr.btf = ptr_to_u64(btf_data);
attr.btf_size = btf_size;
+ /* log_level == 0 and log_buf != NULL means "try loading without
+ * log_buf, but retry with log_buf and log_level=1 on error", which is
+ * consistent across low-level and high-level BTF and program loading
+ * APIs within libbpf and provides a sensible behavior in practice
+ */
+ if (log_level) {
+ attr.btf_log_buf = ptr_to_u64(log_buf);
+ attr.btf_log_size = (__u32)log_size;
+ attr.btf_log_level = log_level;
+ }
+
+ fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, attr_sz);
+ if (fd < 0 && log_buf && log_level == 0) {
+ attr.btf_log_buf = ptr_to_u64(log_buf);
+ attr.btf_log_size = (__u32)log_size;
+ attr.btf_log_level = 1;
+ fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, attr_sz);
+ }
+ return libbpf_err_errno(fd);
+}
+
+int bpf_load_btf(const void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size, bool do_log)
+{
+ LIBBPF_OPTS(bpf_btf_load_opts, opts);
+ int fd;
retry:
if (do_log && log_buf && log_buf_size) {
- attr.btf_log_level = 1;
- attr.btf_log_size = log_buf_size;
- attr.btf_log_buf = ptr_to_u64(log_buf);
+ opts.log_buf = log_buf;
+ opts.log_size = log_buf_size;
+ opts.log_level = 1;
}
- fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, sizeof(attr));
-
+ fd = bpf_btf_load(btf, btf_size, &opts);
if (fd < 0 && !do_log && log_buf && log_buf_size) {
do_log = true;
goto retry;
diff --git a/src/bpf.h b/src/bpf.h
index f79e5fb..5f7d963 100644
--- a/src/bpf.h
+++ b/src/bpf.h
@@ -213,6 +213,23 @@
char *log_buf, size_t log_buf_sz,
int log_level);
+struct bpf_btf_load_opts {
+ size_t sz; /* size of this struct for forward/backward compatibility */
+
+ /* kernel log options */
+ char *log_buf;
+ __u32 log_level;
+ __u32 log_size;
+};
+#define bpf_btf_load_opts__last_field log_size
+
+LIBBPF_API int bpf_btf_load(const void *btf_data, size_t btf_size,
+ const struct bpf_btf_load_opts *opts);
+
+LIBBPF_DEPRECATED_SINCE(0, 8, "use bpf_btf_load() instead")
+LIBBPF_API int bpf_load_btf(const void *btf, __u32 btf_size, char *log_buf,
+ __u32 log_buf_size, bool do_log);
+
LIBBPF_API int bpf_map_update_elem(int fd, const void *key, const void *value,
__u64 flags);
@@ -340,8 +357,6 @@
__u32 query_flags, __u32 *attach_flags,
__u32 *prog_ids, __u32 *prog_cnt);
LIBBPF_API int bpf_raw_tracepoint_open(const char *name, int prog_fd);
-LIBBPF_API int bpf_load_btf(const void *btf, __u32 btf_size, char *log_buf,
- __u32 log_buf_size, bool do_log);
LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
__u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
__u64 *probe_offset, __u64 *probe_addr);
diff --git a/src/libbpf.map b/src/libbpf.map
index 715df3a..08cdfe8 100644
--- a/src/libbpf.map
+++ b/src/libbpf.map
@@ -422,6 +422,7 @@
LIBBPF_0.7.0 {
global:
+ bpf_btf_load;
bpf_program__log_level;
bpf_program__set_log_level;
};
diff --git a/src/libbpf_probes.c b/src/libbpf_probes.c
index 41f2be4..4bdec69 100644
--- a/src/libbpf_probes.c
+++ b/src/libbpf_probes.c
@@ -164,7 +164,7 @@
memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
- btf_fd = bpf_load_btf(raw_btf, btf_len, NULL, 0, false);
+ btf_fd = bpf_btf_load(raw_btf, btf_len, NULL);
free(raw_btf);
return btf_fd;
