EBPF

eBPF (Enhanced Berkeley Packet Filter) is a powerful toolchain capable of compiling high-level languages into a BPF bytecode, which is JITted into local machine code, and can be inserted into a running kernel. It builds atop kprobes, and is in the same family of tools as SystemTap and DTrace. It is driven through the bpf(2) system call, though it is usually more convenient to employ the libbpf library and bpftool binary.

eBPF supports its own BTF debugging information, a simplified form of DWARF.

bpftool

bpftool can be built in tools/bpf of the installed kernel's source.

Compiling eBPF

LLVM

LLVM has enjoyed bpf backend support since 3.7. Compile using -target bpf. readelf on the resulting object ought look like:

ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              REL (Relocatable file)
  Machine:                           Linux BPF
  Version:                           0x1
  Entry point address:               0x0
  Start of program headers:          0 (bytes into file)
  Start of section headers:          360 (bytes into file)
  Flags:                             0x0
...

JIT

• JIT requires the net.core.bpf_jit_enable sysctl to be set

See Also

• XDP
• Cilium.io's BPF and XDP Reference Guide
• zoidbergwill's awesome-ebpf list