Commit 0ed08d67 authored by Andrii Nakryiko's avatar Andrii Nakryiko
Browse files

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: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-3-andrii@kernel.org
parent 4cf23a3c

tools/lib/bpf/bpf.c

+50 −9
Original line number Diff line number Diff line
@@ -1047,24 +1047,65 @@ int bpf_raw_tracepoint_open(const char *name, int prog_fd) 
	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;

	}



retry:

	if (do_log && log_buf && log_buf_size) {

		attr.btf_log_level = 1;

		attr.btf_log_size = log_buf_size;

	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;



	fd = sys_bpf_fd(BPF_BTF_LOAD, &attr, sizeof(attr));

retry:

	if (do_log && log_buf && log_buf_size) {

		opts.log_buf = log_buf;

		opts.log_size = log_buf_size;

		opts.log_level = 1;

	}



	fd = bpf_btf_load(btf, btf_size, &opts);

	if (fd < 0 && !do_log && log_buf && log_buf_size) {

		do_log = true;

		goto retry;

tools/lib/bpf/bpf.h

+17 −2
Original line number Diff line number Diff line
@@ -213,6 +213,23 @@ LIBBPF_API int bpf_verify_program(enum bpf_prog_type type, 
				  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 @@ LIBBPF_API int bpf_prog_query(int target_fd, enum bpf_attach_type type, 
			      __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);

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -422,6 +422,7 @@ LIBBPF_0.6.0 { 


LIBBPF_0.7.0 {

	global:

		bpf_btf_load;

		bpf_program__log_level;

		bpf_program__set_log_level;

};

tools/lib/bpf/libbpf_probes.c

+1 −1
Original line number Diff line number Diff line
@@ -164,7 +164,7 @@ int libbpf__load_raw_btf(const char *raw_types, size_t types_len, 
	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;