[RFC bpf-next v4 0/7] Introduce eBPF support for HID devices (new attempt)

[Benjamin Tissoires <benjamin.tissoires@redhat.com>]

Hi,

so after the reviews from v3, and some discussion with Alexei, I am
back with a new version of HID-BPF.

This version is not complete (thus the RFC), but I'd like to share
it now to get initial feedback, in case I am too far from the actual
goal.

FTR, the goal is to provide some changes in the core verifier/btf so
that we can plug in HID-BPF independently from BPF core. This way we can
extend it without having to care about bpf-next.

The things I am not entirely sure are:
- do we need only fentry/fexit/fmod_ret BPF program types or should
  programs that modify the data stream use a different kind?
- patch 3/7 is probably not the correct approach (see comments in the
  patch itself)

We are missing quite a few bits here:
- selftests for patches 1 to 4
- add the ability to attach a program to a struct device, and run that
  program only for that struct device
- when running through bpf_prog_test_run_opts, how can we ensure we are
  talking to the correct device? (I have a feeling this is linked to the
  previous point)
- how can we reconnect the device when a report descriptor fixup BPF
  program is loaded (would it make sense to allow some notifications on
  when a BPF program is attached/detached to a device, and which
  function have been traced?)

Cheers,
Benjamin

Benjamin Tissoires (7):
  bpf/btf: also allow kfunc in tracing programs
  bpf/verifier: allow kfunc to return an allocated mem
  error-inject: add new type that carries if the function is non
    sleepable
  btf: Add a new kfunc set which allows to mark a function to be
    sleepable
  HID: initial BPF new way implementation
  samples/bpf: add new hid_mouse example
  selftests/bpf: add tests for the HID-bpf initial implementation

 drivers/hid/hid-core.c                       | 115 +++++
 include/asm-generic/error-injection.h        |   1 +
 include/linux/btf.h                          |   8 +
 include/linux/hid_bpf.h                      |  29 ++
 kernel/bpf/btf.c                             |  50 +-
 kernel/bpf/verifier.c                        |  76 ++-
 lib/error-inject.c                           |   2 +
 samples/bpf/.gitignore                       |   1 +
 samples/bpf/Makefile                         |  23 +
 samples/bpf/hid_mouse.bpf.c                  |  59 +++
 samples/bpf/hid_mouse.c                      | 131 +++++
 tools/testing/selftests/bpf/config           |   3 +
 tools/testing/selftests/bpf/prog_tests/hid.c | 482 +++++++++++++++++++
 tools/testing/selftests/bpf/progs/hid.c      |  32 ++
 14 files changed, 987 insertions(+), 25 deletions(-)
 create mode 100644 include/linux/hid_bpf.h
 create mode 100644 samples/bpf/hid_mouse.bpf.c
 create mode 100644 samples/bpf/hid_mouse.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/hid.c
 create mode 100644 tools/testing/selftests/bpf/progs/hid.c

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2.35.1