libbpf/libbpf v0.6.0

libbpf v0.6

on GitHub

Important updates towards Libbpf 1.0

• a first big batch of deprecated APIs; compiler will let you know or grep for "LIBBPF_DEPRECATED". Please also double-check https://github.com/libbpf/libbpf/wiki/Libbpf-1.0-migration-guide.
• documentation for a bunch of APIs added, available on https://libbpf.readthedocs.io/en/latest/api.html;
• libbpf version APIs added: compile-time LIBBPF_MAJOR_VERSION/LIBBPF_MINOR_VERSION and runtime libbpf_major_version()/libbpf_minor_version()/libbpf_version_string();
• stricter logic for SEC() definition handling (opt-in until libbpf v1.0); see https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#stricter-and-more-uniform-bpf-program-section-name-sec-handling for details.
• function name will be used when pinning if LIBBPF_STRICT_SEC_NAME strict mode flag is specified;

New features and APIs:

• support custom .rodata.* and .data.* data sections;
• bpf_program__attach_kprobe() and bpf_program__attach_uprobe() supports older kernels now (don't forget about bpf_link__destroy() when you are done!);
• BPF_MAP_TYPE_PROG_ARRAY can be initialized statically with syntax similar to map-in-map initialization (see 472c072 for an example);
• libbpf-less "light" skeleton gained new capabilities and got a bunch of fixes;
• BTF support for BTF_KIND_DECL_TAG and BTF_KIND_TYPE_TAG;
• new bpf_prog_load() and bpf_map_create() APIs supersede a whole zoo of to-be-deprecated APIs;
• support for writable raw tracepoints (SEC("raw_tp.w/...")) added;
• btf__add_btf() API for appending entire contents of BTF to another BTF object;
• bpf_program__insns() and bpf_program__insn_cnt() to access underlying BPF assembly instructions; can be used for inspection or BPF program cloning.
• a bunch of older APIs (perf_buffer__new(), btf__dedup(), btf_dump__new(), etc) were modernized to use OPTS infrastructure.

BPF-side APIs and features:

• unstable BPF helpers (kernel function calls) support for kernel modules;
• bpf_trace_vprintk() helper and corresponding bpf_printk() macro enhancements. Note, bpf_printk() will now attempt to use static global functions, so on very old kernels this might break existing programs. Please #define BPF_NO_GLOBAL_DATA before #include <bpf/bpf_helpers.h> if that's the case for you.
• bpf_get_branch_snapshot() helper;
• bpf_skc_to_unix_sock() helper;
• bpf_find_vma() helper;
• SEC("tc") added as a replacement for SEC("classifier").

Bug fixes and compatibility improvements:

• libbpf now guarantees that all FDs for BPF programs, maps, BTFs, and links are strictly greater than 0, which is important for some BPF UAPIs;
• no need to use __uint(key_size, ...) for special BPF maps (e.g., BPF_MAP_PERF_EVENT_ARRAY). Libbpf automatically downgrades __type(key, int) into key_size, if a map doesn't support BTF types for keys and values;
• endianness fixes in BPF_CORE_READ_BITFIELD_PROBED() macro;
• btf_dump__dump_type_data() improvements for handling unaligned data;
• various fixes and improvements found though fuzzing and sanitizers.

Full Changelog: v0.5.0...v0.6.0