On Wed, Sep 15, 2021 at 09:34:21PM IST, Andrii Nakryiko wrote:

On Tue, Sep 14, 2021 at 10:09 PM Kumar Kartikeya Dwivedi
[off-list ref] wrote:

quoted

This set enables kernel module function calls, and also modifies verifier logic
to permit invalid kernel function calls as long as they are pruned as part of
dead code elimination. This is done to provide better runtime portability for
BPF objects, which can conditionally disable parts of code that are pruned later
by the verifier (e.g. const volatile vars, kconfig options). libbpf
modifications are made along with kernel changes to support module function
calls. The set includes gen_loader support for emitting kfunc relocations.

It also converts TCP congestion control objects to use the module kfunc support
instead of relying on IS_BUILTIN ifdef.

Changelog:
----------
v2 -> v3:
v2: https://lore.kernel.org/bpf/20210914123750.460750-1-memxor@gmail.com (local)

 * Fix issues pointed out by Kernel Test Robot
 * Fix find_kfunc_desc to also take offset into consideration when comparing

See [0]:


  [  444.075332] mod kfunc i=42
  [  444.075383] mod kfunc i=42
  [  444.075522] mod kfunc i=42
  [  444.075578] mod kfunc i=42
  [  444.075631] mod kfunc i=42
  [  444.075683] mod kfunc i=42
  [  444.075735] mod kfunc i=42
  [  444.0
This step has been truncated due to its large size. Download the full
logs from the
menu once the workflow run has completed.

  [0] https://github.com/kernel-patches/bpf/runs/3606513281?check_suite_focus=true

I'll change it to not use printk in the next spin (maybe just set a variable).
This probably blew up because of parallel test_progs stuff, since it would be
called for each sys_enter as long the raw_tp prog is attached.

--
Kartikeya