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android / platform / external / libbpf / cb174c5
commitcb174c5b8d134955e7cd2f7b75b4a18d82af8068[log] [tgz]
authorAndrii Nakryiko <andriin@fb.com>Wed Jun 17 08:47:22 2020 -0700
committerAndrii Nakryiko <andrii.nakryiko@gmail.com>Wed Jun 17 11:48:22 2020 -0700
tree91a25f6daab3a05d4fc5276499f14f6616d8ed35
parent17f747ed38419ca207570351920c4cbed5c25958 [diff]
sync: auto-generate latest BPF helpers

Latest changes to BPF helper definitions.
1 file changed
tree: 91a25f6daab3a05d4fc5276499f14f6616d8ed35
  1. include/
  2. scripts/
  3. src/
  4. travis-ci/
  5. .lgtm.yml
  6. .travis.yml
  7. BPF-CHECKPOINT-COMMIT
  8. CHECKPOINT-COMMIT
  9. LICENSE
  10. LICENSE.BSD-2-Clause
  11. LICENSE.LPGL-2.1
  12. README.md
README.md

This is a mirror of bpf-next linux tree's tools/lib/bpf directory plus its supporting header files.

The following files will by sync'ed with bpf-next repo:

  • src/ <-> bpf-next/tools/lib/bpf/
  • include/uapi/linux/bpf_common.h <-> bpf-next/tools/include/uapi/linux/bpf_common.h
  • include/uapi/linux/bpf.h <-> bpf-next/tools/include/uapi/linux/bpf.h
  • include/uapi/linux/btf.h <-> bpf-next/tools/include/uapi/linux/btf.h
  • include/uapi/linux/if_link.h <-> bpf-next/tools/include/uapi/linux/if_link.h
  • include/uapi/linux/if_xdp.h <-> bpf-next/tools/include/uapi/linux/if_xdp.h
  • include/uapi/linux/netlink.h <-> bpf-next/tools/include/uapi/linux/netlink.h
  • include/tools/libc_compat.h <-> bpf-next/tools/include/tools/libc_compat.h

Other header files at this repo (include/linux/*.h) are reduced versions of their counterpart files at bpf-next's tools/include/linux/*.h to make compilation successful.

Build Build Status Total alerts Coverity

libelf is an internal dependency of libbpf and thus it is required to link against and must be installed on the system for applications to work. pkg-config is used by default to find libelf, and the program called can be overridden with PKG_CONFIG. If using pkg-config at build time is not desired, it can be disabled by setting NO_PKG_CONFIG=1 when calling make.

To build both static libbpf.a and shared libbpf.so:

$ cd src
$ make

To build only static libbpf.a library in directory build/ and install them together with libbpf headers in a staging directory root/:

$ cd src
$ mkdir build root
$ BUILD_STATIC_ONLY=y OBJDIR=build DESTDIR=root make install

To build both static libbpf.a and shared libbpf.so against a custom libelf dependency installed in /build/root/ and install them together with libbpf headers in a build directory /build/root/:

$ cd src
$ PKG_CONFIG_PATH=/build/root/lib64/pkgconfig DESTDIR=/build/root make install

Distributions

Distributions packaging libbpf from this mirror:

Benefits of packaging from the mirror over packaging from kernel sources:

  • Consistent versioning across distributions.
  • No ties to any specific kernel, transparent handling of older kernels. Libbpf is designed to be kernel-agnostic and work across multitude of kernel versions. It has built-in mechanisms to gracefully handle older kernels, that are missing some of the features, by working around or gracefully degrading functionality. Thus libbpf is not tied to a specific kernel version and can/should be packaged and versioned independently.
  • Continuous integration testing via TravisCI.
  • Static code analysis via LGTM and Coverity.

Package dependencies of libbpf, package names may vary across distros:

  • zlib
  • libelf

BPF CO-RE (Compile Once – Run Everywhere)

Libbpf supports building BPF CO-RE-enabled applications, which, in contrast to BCC, do not require Clang/LLVM runtime being deployed to target servers and doesn't rely on kernel-devel headers being available.

It does rely on kernel to be built with BTF type information, though. Some major Linux distributions come with kernel BTF already built in:

  • Fedora 31+
  • RHEL 8.2+
  • OpenSUSE Tumbleweed (in the next release, as of 2020-06-04)
  • Arch Linux (from kernel 5.7.1.arch1-1)

If your kernel doesn‘t come with BTF built-in, you’ll need to build custom kernel. You'll need:

  • pahole 1.16+ tool (part of dwarves package), which performs DWARF to BTF conversion;
  • kernel built with CONFIG_DEBUG_INFO_BTF=y option;
  • you can check if your kernel has BTF built-in by looking for /sys/kernel/btf/vmlinux file:
$ ls -la /sys/kernel/btf/vmlinux
-r--r--r--. 1 root root 3541561 Jun  2 18:16 /sys/kernel/btf/vmlinux

To develop and build BPF programs, you'll need Clang/LLVM 10+. The following distributions have Clang/LLVM 10+ packaged by default:

  • Fedora 32+
  • Ubuntu 20.04+
  • Arch Linux

Otherwise, please make sure to update it on your system.

The following resources are useful to understand what BPF CO-RE is and how to use it:

License

This work is dual-licensed under BSD 2-clause license and GNU LGPL v2.1 license. You can choose between one of them if you use this work.

SPDX-License-Identifier: BSD-2-Clause OR LGPL-2.1