список вспомогательных функций eBPF (list of eBPF helper functions)
Имя (Name)
BPF-HELPERS - list of eBPF helper functions
Описание (Description)
The extended Berkeley Packet Filter (eBPF) subsystem consists in
programs written in a pseudo-assembly language, then attached to
one of the several kernel hooks and run in reaction of specific
events. This framework differs from the older, "classic" BPF (or
"cBPF") in several aspects, one of them being the ability to call
special functions (or "helpers") from within a program. These
functions are restricted to a white-list of helpers defined in
the kernel.
These helpers are used by eBPF programs to interact with the
system, or with the context in which they work. For instance,
they can be used to print debugging messages, to get the time
since the system was booted, to interact with eBPF maps, or to
manipulate network packets. Since there are several eBPF program
types, and that they do not run in the same context, each program
type can only call a subset of those helpers.
Due to eBPF conventions, a helper can not have more than five
arguments.
Internally, eBPF programs call directly into the compiled helper
functions without requiring any foreign-function interface. As a
result, calling helpers introduces no overhead, thus offering
excellent performance.
This document is an attempt to list and document the helpers
available to eBPF developers. They are sorted by chronological
order (the oldest helpers in the kernel at the top).
