7065a809fc
Syncing latest libbpf commits from kernel repository. Baseline bpf-next commit: 86ce322d21eb032ed8fdd294d0fb095d2debb430 Checkpoint bpf-next commit: 303dcc25b5c782547eb13b9f29426de843dd6f34 Baseline bpf commit: 78031381ae9c88f4f914d66154f4745122149c58 Checkpoint bpf commit: 6185266c5a853bb0f2a459e3ff594546f277609b Alexei Starovoitov (1): bpf: Count the number of times recursion was prevented Florent Revest (2): bpf: Be less specific about socket cookies guarantees bpf: Expose bpf_get_socket_cookie to tracing programs Hangbin Liu (1): bpf: Remove blank line in bpf helper description comment Jesper Dangaard Brouer (2): bpf: bpf_fib_lookup return MTU value as output when looked up bpf: Add BPF-helper for MTU checking Jonas Bonn (1): Revert "GTP: add support for flow based tunneling API" Martin KaFai Lau (1): libbpf: Ignore non function pointer member in struct_ops Stanislav Fomichev (1): libbpf: Use AF_LOCAL instead of AF_INET in xsk.c Yonghong Song (3): bpf: Add bpf_for_each_map_elem() helper libbpf: Move function is_ldimm64() earlier in libbpf.c libbpf: Support subprog address relocation include/uapi/linux/bpf.h | 140 +++++++++++++++++++++++++++++++++-- include/uapi/linux/if_link.h | 1 - src/libbpf.c | 98 +++++++++++++++++++----- src/xsk.c | 2 +- 4 files changed, 213 insertions(+), 28 deletions(-) -- 2.24.1
BPF/libbpf usage and questions
Please check out libbpf-bootstrap and the companion blog post for the examples of building BPF applications with libbpf. libbpf-tools are also a good source of the real-world libbpf-based tracing tools.
All general BPF questions, including kernel functionality, libbpf APIs and their application, should be sent to bpf@vger.kernel.org mailing list. You can subscribe to it here and search its archive here. Please search the archive before asking new questions. It very well might be that this was already addressed or answered before.
bpf@vger.kernel.org is monitored by many more people and they will happily try to help you with whatever issue you have. This repository's PRs and issues should be opened only for dealing with issues pertaining to specific way this libbpf mirror repo is set up and organized.
Build
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)
- Ubuntu 20.10
- Debian 11 (amd64/arm64)
If your kernel doesn't come with BTF built-in, you'll need to build custom kernel. You'll need:
pahole1.16+ tool (part ofdwarvespackage), which performs DWARF to BTF conversion;- kernel built with
CONFIG_DEBUG_INFO_BTF=yoption; - you can check if your kernel has BTF built-in by looking for
/sys/kernel/btf/vmlinuxfile:
$ 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
- Ubuntu 20.10 (LLVM 11)
- Debian 11 (LLVM 11)
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:
- BPF Portability and CO-RE
- HOWTO: BCC to libbpf conversion
- libbpf-tools in BCC repo contain lots of real-world tools converted from BCC to BPF CO-RE. Consider converting some more to both contribute to the BPF community and gain some more experience with it.
Details
This is a mirror of bpf-next Linux source
tree's
tools/lib/bpf directory plus its supporting header files.
All the gory details of syncing can be found in scripts/sync-kernel.sh
script.
Some header files in this repo (include/linux/*.h) are reduced versions of
their counterpart files at
bpf-next's
tools/include/linux/*.h to make compilation successful.
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