Re: [PATCH bpf-next 04/15] bpf: Support bpf program calling kernel function

On Thu, Mar 18, 2021 at 06:03:49PM -0700, Andrii Nakryiko wrote: > On Tue, Mar 16, 2021 at 12:01 AM Martin KaFai Lau wrote: > > > > This patch adds support to BPF verifier to allow bpf program calling > > kernel function directly. > > > > The use case included in this set is to allow bpf-tcp-cc to

Re: [PATCH bpf-next 04/15] bpf: Support bpf program calling kernel function

On 3/18/21 6:03 PM, Andrii Nakryiko wrote: + desc->imm = BPF_CAST_CALL(addr) - __bpf_call_base; Is this difference guaranteed to always fit within s32? we have this restriction in many places: JIT, dispatcher, trampoline, and bpf interpreter. Modules and kernel .text are in the same 4G

Re: [PATCH bpf-next 04/15] bpf: Support bpf program calling kernel function

On Tue, Mar 16, 2021 at 12:01 AM Martin KaFai Lau wrote: > > This patch adds support to BPF verifier to allow bpf program calling > kernel function directly. > > The use case included in this set is to allow bpf-tcp-cc to directly > call some tcp-cc helper functions (e.g. "tcp_cong_avoid_ai()").

[PATCH bpf-next 04/15] bpf: Support bpf program calling kernel function

This patch adds support to BPF verifier to allow bpf program calling kernel function directly. The use case included in this set is to allow bpf-tcp-cc to directly call some tcp-cc helper functions (e.g. "tcp_cong_avoid_ai()"). Those functions have already been used by some kernel tcp-cc implemen