9.7.2.2 Register Names

The eBPF processor provides ten general-purpose 64-bit registers, which are read-write, and a read-only frame pointer register:

%r0 .. %r9

General-purpose registers.

%r10

Frame pointer register.

Some registers have additional names, to reflect their role in the eBPF ABI:

%a

This is %r0.

%ctx

This is %r6.

%fp

This is %r10.