On Fri, Nov 22, 2019 at 12:08 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
>
> This gets rid of indirect jumps for BPF tail calls whenever possible.
> The series adds emission for *direct* jumps for tail call maps in order
> to avoid the retpoline overhead from a493a87f38cf ("bpf, x64: implement
> retpoline for tail call") for situations that allow for it, meaning,
> for known constant keys at verification time which are used as index
> into the tail call map. See patch 7/8 for more general details.
>
> Thanks!
>
> v1 -> v2:
> - added more test cases
> - u8 ip_stable -> bool (Andrii)
> - removed bpf_map_poke_{un,}lock and simplified the code (Andrii)
> - added break into prog_array_map_poke_untrack since there's just
> one prog (Andrii)
> - fixed typo: for for in commit msg (Andrii)
> - reworked __bpf_arch_text_poke (Andrii)
> - added subtests, and comment on tests themselves, NULL-NULL
> transistion (Andrii)
> - in constant map key tracking I've moved the map_poke_track callback
> to once we've finished creating the poke tab as otherwise concurrent
> access from tail call map would blow up (since we realloc the table)
> rfc -> v1:
> - Applied Alexei's and Andrii's feeback from
> https://lore.kernel.org/bpf/cover.1573779287.git.daniel@xxxxxxxxxxxxx/T/#t
Applied. Thanks!
