Recently diagnosing a regression [1] would have been easier if struct bpf_prog_info had some comments explaining its usage. As I found it hard to generate comments for some parts of the struct,q what is here is a mix of mostly hand written, but some AI written, comments. [1] https://lore.kernel.org/lkml/CAP-5=fWJQcmUOP7MuCA2ihKnDAHUCOBLkQFEkQES-1ZZTrgf8Q@xxxxxxxxxxxxxx/ Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx> --- include/uapi/linux/bpf.h | 187 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 186 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 233de8677382..008b559dc5c5 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -6607,45 +6607,230 @@ struct sk_reuseport_md { #define BPF_TAG_SIZE 8 +/** + * struct bpf_prog_info - Information about a BPF program. + * + * This structure is used by the bpf(BPF_OBJ_GET_INFO_BY_FD) syscall to retrieve + * metadata about a loaded BPF program. When values like the jited_prog_insns + * are desired typically two syscalls will be made, the first to determine the + * length of the buffers and the second with buffers for the syscall to fill + * in. The variables within the struct are ordered to minimize padding. + */ struct bpf_prog_info { + /** + * @type: The type of the BPF program (e.g., + * BPF_PROG_TYPE_SOCKET_FILTER, BPF_PROG_TYPE_KPROBE). This defines + * where the program can be attached. + */ __u32 type; + /** + * @id: A unique, kernel-assigned ID for the loaded BPF program. + */ __u32 id; + /** + * @tag: A user-defined tag for the program, often a hash of the + * object file it came from. Size is BPF_TAG_SIZE (8 bytes). + */ __u8 tag[BPF_TAG_SIZE]; + /** + * @jited_prog_len: As an in argument this is the length of the + * jited_prog_insns buffer. As an out argument, the length of the + * JIT-compiled (native machine code) program image in bytes. + */ __u32 jited_prog_len; + /** + * @xlated_prog_len: As an in argument this is the length of the + * xlated_prog_insns buffer. As an out argument, the length of the + * translated BPF bytecode in bytes, after the verifier has potentially + * modified it. 'xlated' is short for 'translated'. + */ __u32 xlated_prog_len; + /** + * @jited_prog_insns: When 0 (NULL) this is ignored by the kernel. When + * non-zero a pointer to a buffer is expected and the kernel will write + * jited_prog_len(s) worth of JIT-compiled machine code instructions into + * the buffer. + */ __aligned_u64 jited_prog_insns; + /** + * @xlated_prog_insns: When 0 (NULL) this is ignored by the kernel. When + * non-zero a pointer to a buffer is expected and the kernel will write + * xlated_prog_len(s) worth of translated, after BPF verification, BPF + * bytecode into the buffer. + */ __aligned_u64 xlated_prog_insns; - __u64 load_time; /* ns since boottime */ + /** + * @load_time: The timestamp (in nanoseconds since boot time) when the + * program was loaded into the kernel. + */ + __u64 load_time; + /** + * @created_by_uid: The user ID of the process that loaded this program. + */ __u32 created_by_uid; + /** + * @nr_map_ids: As an in argument this is the length of the map_ids + * buffer in sizes of u32 (4 bytes). As an out argument, the number of + * BPF maps used by this BPF program. + */ __u32 nr_map_ids; + /** + * @map_ids: When 0 (NULL) this is ignored by the kernel. When non-zero + * a pointer to a buffer is expected and the kernel will write + * nr_map_ids(s) worth of u32 kernel allocated BPF map id values into the + * buffer. + */ __aligned_u64 map_ids; + /** + * @name: The name of the program, as specified in the ELF object file. + * The max length is BPF_OBJ_NAME_LEN (16 characters). + */ char name[BPF_OBJ_NAME_LEN]; + /** + * @ifindex: If the program is attached to a network device (netdev), + * this field holds the interface index. + */ __u32 ifindex; + /** + * @gpl_compatible: A flag indicating if the program is compatible with + * a GPL license. This is important for using certain GPL-only helpers. + */ __u32 gpl_compatible:1; __u32 :31; /* alignment pad */ + /** + * @netns_dev: The device identifier of the network namespace the + * program is attached to. + */ __u64 netns_dev; + /** + * @netns_ino: The inode number of the network namespace the program is + * attached to. + */ __u64 netns_ino; + /** + * @nr_jited_ksyms: As an in argument this is the length of the + * jited_ksyms buffer in sizes of u64 (8 bytes). As an out argument, the + * number of kernel symbols that the BPF program calls. + */ __u32 nr_jited_ksyms; + /** + * @nr_jited_func_lens: As an in argument this is the length of the + * jited_func_lens buffer in sizes of u32 (4 bytes). As an out argument, + * the number of distinct functions within the JIT-ed program. + */ __u32 nr_jited_func_lens; + /** + * @jited_ksyms: When 0 (NULL) this is ignored by the kernel. When + * non-zero a pointer to a buffer is expected and the kernel will write + * nr_jited_ksyms(s) worth of addresses of kernel symbols into the u64 + * buffer. + */ __aligned_u64 jited_ksyms; + /** + * @jited_func_lens: When 0 (NULL) this is ignored by the kernel. When + * non-zero a pointer to a buffer is expected and the kernel will write + * nr_jited_func_lens(s) worth of lengths into the u32 buffer. + */ __aligned_u64 jited_func_lens; + /** + * @btf_id: The ID of the BTF (BPF Type Format) object associated with + * this program, which contains type information for debugging and + * introspection. + */ __u32 btf_id; + /** + * @func_info_rec_size: The size in bytes of a single `bpf_func_info` + * record. + */ __u32 func_info_rec_size; + /** + * @func_info: When 0 (NULL) this is ignored by the kernel. When + * non-zero a pointer to a buffer is expected and the kernel will write + * nr_func_info(s) worth of func_info_rec_size values. + */ __aligned_u64 func_info; + /** + * @nr_func_info: As an in argument this is the length of the func_info + * buffer in sizes of func_info_rec_size. As an out argument, the number + * of `bpf_func_info` records available. + */ __u32 nr_func_info; + /** + * @nr_line_info: As an in argument this is the length of the line_info + * buffer in sizes of line_info_rec_size. As an out argument, the number + * of `bpf_line_info` records, which map BPF instructions to source code + * lines. + */ __u32 nr_line_info; + /** + * @line_info: When 0 (NULL) this is ignored by the kernel. When + * non-zero a pointer to a buffer is expected and the kernel will write + * nr_line_info(s) worth of line_info_rec_size values. + */ __aligned_u64 line_info; + /** + * @jited_line_info: When 0 (NULL) this is ignored by the kernel. When + * non-zero a pointer to a buffer is expected and the kernel will write + * nr_jited_line_info(s) worth of jited_line_info_rec_size values. + */ __aligned_u64 jited_line_info; + /** + * @nr_line_info: As an in argument this is the length of the + * jited_line_info buffer in sizes of jited_line_info_rec_size. As an + * out argument, the number of `bpf_line_info` records, which map JIT-ed + * instructions to source code lines. + */ __u32 nr_jited_line_info; + /** + * @line_info_rec_size: The size in bytes of a `bpf_line_info` record. + */ __u32 line_info_rec_size; + /** + * @jited_line_info_rec_size: The size in bytes of a `bpf_line_info` + * record for JIT-ed code. + */ __u32 jited_line_info_rec_size; + /** + * @nr_prog_tags: As an in argument this is the length of the prog_tags + * buffer in sizes of BPF_TAG_SIZE (8 bytes). As an out argument, the + * number of program tags, which are hashes of programs that this + * program can tail-call. + */ __u32 nr_prog_tags; + /** + * @prog_tags: When 0 (NULL) this is ignored by the kernel. When + * non-zero a pointer to a buffer is expected and the kernel will write + * nr_prog_tags(s) worth of BPF_TAG_SIZE values. + */ __aligned_u64 prog_tags; + /** + * @run_time_ns: The total accumulated execution time of the program in + * nanoseconds. + */ __u64 run_time_ns; + /** + * @run_cnt: The total number of times the program has been executed. + */ __u64 run_cnt; + /** + * @recursion_misses: The number of failed tail calls due to reaching + * the recursion limit. + */ __u64 recursion_misses; + /** + * @verified_insns: The number of instructions processed by the + * verifier. + */ __u32 verified_insns; + /** + * @attach_btf_obj_id: If attached via BTF (e.g., fentry/fexit), this is + * the BTF object ID of the target object (e.g., kernel vmlinux). + */ __u32 attach_btf_obj_id; + /** + * @attach_btf_id: The BTF type ID of the function or tracepoint this + * program is attached to. + */ __u32 attach_btf_id; } __attribute__((aligned(8))); -- 2.51.0.338.gd7d06c2dae-goog
