On Wed, Aug 2, 2023 at 11:38 AM Steven Rostedt [off-list ref] wrote:

On Wed, 2 Aug 2023 11:24:12 -0700
Alexei Starovoitov [off-list ref] wrote:

quoted

This is a non starter.
bpf progs expect arch dependent 'struct pt_regs *' and we cannot change that.

If the progs are compiled into native code, isn't there optimizations that
could be done? That is, if ftrace_regs is available, and the bpf program is
just using the subset of pt_regs, is it possible that it could be compiled
to use ftrace_regs?

Forgive my ignorance on how BPF programs turn into executables when running
in the kernel.

Right. It's possible for the verifier to do an offset rewrite,
forbid certain access, always return 0 on load from certain offset,
and so on.
It's all non trivial amount of work.
ftrace_partial_regs() from ftrace_regs into pt_regs is so much simpler.