On Mon, Apr 1, 2024 at 9:29 AM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> On Fri, 2024-03-29 at 11:47 -0700, Andrii Nakryiko wrote:
> > Add two new BPF instructions for dealing with per-CPU memory.
> >
> > One, BPF_LDX | BPF_ADDR_PERCPU | BPF_DW (where BPF_ADD_PERCPU is unused
> > 0xe0 opcode), resolved provided per-CPU address (offset) to an absolute
> > address where per-CPU data resides for "this" CPU. This is the most universal,
> > and, strictly speaking, the only per-CPU BPF instruction necessary.
> >
> > I also added BPF_LDX | BPF_MEM_PERCPU | BPF_{B,H,W,DW} (BPF_MEM_PERCPU using
> > another unused 0xc0 opcode), which can be considered an optimization
> > instruction, which allows to *read* per-CPU data up to 8 bytes in one
> > instruction, without having to first resolve the address and then
> > dereferencing the memory. This one is used in inlining of
> > bpf_get_smp_processor_id(), but it would be fine to implement the latter with
> > BPF_ADD_PERCPU, followed by normal BPF_LDX | BPF_MEM, so I'm fine dropping
> > this one, if requested.
>
> Hi Andrii,
>
> I've read through the series and it looks good
> (modulo architecture related issues reported by CI).
Should I add your acks in the next revision?
>
> Thanks,
> Eduard
