Investigate KFUNC/KRETFUNC support

linuxppc / issues

Issues repository for linuxppc

5 stars 0 forks source link

Investigate KFUNC/KRETFUNC support #363

Open antonblanchard opened 3 years ago

antonblanchard commented 3 years ago

A new way of calling into BPF called KFUNC/KRETFUNC was added recently. We should investigate if it will lower the cost of making BPF calls on PowerPC

antonblanchard commented 3 years ago

@rnav FYI

chleroy commented 3 years ago

Is it https://github.com/linuxppc/linux/commit/e6ac2450d6dee3121cd8bbf2907b78a68a8a353d ?

rnav commented 3 years ago

Yes, there are a few items related to BPF that we are working on:

@BangoriaRavi is working on adding support for BPF_PROBE_MEM, which is required for BTF. I think he is close to posting the patches for this soon. This is required to support kfunc.
Another area that helps with BPF performance is support for BPF trampolines, as a way to call into BPF programs without going through ftrace. This requires support for ftrace direct calls for which I have posted RFCs and plan to post a v1 soon: https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=216968

rnav commented 3 years ago

Is it linuxppc/linux@e6ac245 ?

Yes. Also: https://lwn.net/Articles/856005/

chleroy commented 3 years ago

Maybe porting commit https://github.com/linuxppc/linux/commit/40272035e1d0edcd515ad45be297c4cce044536d to powerpc64 could also improve performance ?

iamjpn commented 2 years ago

Series porting commit https://github.com/linuxppc/linux/commit/40272035e1d0edcd515ad45be297c4cce044536d to ppc64 posted here: https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=255361

rnav commented 2 years ago

Support for BPF_PROBE_MEM has been merged: https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=284762

Early RFC enabling Trampoline support was posted recently: https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=284762