On Wed, Aug 2, 2023 at 11:38 AM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > On Wed, 2 Aug 2023 11:24:12 -0700 > Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote: > > > 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.
