[PATCH HID v2 00/16] HID: convert HID-BPF into using bpf_struct_ops

Benjamin Tissoires
2024-06-07T15:28:32Z

The purpose of this series is to rethink how HID-BPF is invoked.
Currently it implies a jmp table, a prog fd bpf_map, a preloaded tracing
bpf program and a lot of manual work for handling the bpf program
lifetime and addition/removal.

OTOH, bpf_struct_ops take care of most of the bpf handling leaving us
with a simple list of ops pointers, and we can directly call the
struct_ops program from the kernel as a regular function.

The net gain right now is in term of code simplicity and lines of code
removal (though is an API breakage), but udev-hid-bpf is able to handle
such breakages.

In the near future, we will be able to extend the HID-BPF struct_ops
with entrypoints for hid_hw_raw_request() and hid_hw_output_report(),
allowing for covering all of the initial use cases:
- firewalling a HID device
- fixing all of the HID device interactions (not just device events as
it is right now).

The matching user-space loader (udev-hid-bpf) MR is at
https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/86

I'll put it out of draft once this is merged.

Cheers,
Benjamin

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
Changes in v2:
- drop HID_BPF_FLAGS enum and use BPF_F_BEFORE instead
- fix .init_members to not open code member->offset
- allow struct hid_device to be writeable from HID-BPF for its name,
uniq and phys
- Link to v1: https://lore.kernel.org/r/20240528-hid_bpf_struct_ops-v1-0-8c6663df27d8@kernel.org

---
Benjamin Tissoires (16):
HID: rename struct hid_bpf_ops into hid_ops
HID: bpf: add hid_get/put_device() helpers
HID: bpf: implement HID-BPF through bpf_struct_ops
selftests/hid: convert the hid_bpf selftests with struct_ops
HID: samples: convert the 2 HID-BPF samples into struct_ops
HID: bpf: add defines for HID-BPF SEC in in-tree bpf fixes
HID: bpf: convert in-tree fixes into struct_ops
HID: bpf: remove tracing HID-BPF capability
selftests/hid: add subprog call test
Documentation: HID: amend HID-BPF for struct_ops
Documentation: HID: add a small blurb on udev-hid-bpf
HID: bpf: Artist24: remove unused variable
HID: bpf: error on warnings when compiling bpf objects
bpf: allow bpf helpers to be used into HID-BPF struct_ops
HID: bpf: rework hid_bpf_ops_btf_struct_access
HID: bpf: make part of struct hid_device writable

Documentation/hid/hid-bpf.rst | 173 ++++---
drivers/hid/bpf/Makefile | 2 +-
drivers/hid/bpf/entrypoints/Makefile | 93 ----
drivers/hid/bpf/entrypoints/README | 4 -
drivers/hid/bpf/entrypoints/entrypoints.bpf.c | 25 -
drivers/hid/bpf/entrypoints/entrypoints.lskel.h | 248 ---------
drivers/hid/bpf/hid_bpf_dispatch.c | 266 +++-------
drivers/hid/bpf/hid_bpf_dispatch.h | 12 +-
drivers/hid/bpf/hid_bpf_jmp_table.c | 565 ---------------------
drivers/hid/bpf/hid_bpf_struct_ops.c | 298 +++++++++++
drivers/hid/bpf/progs/FR-TEC__Raptor-Mach-2.bpf.c | 9 +-
drivers/hid/bpf/progs/HP__Elite-Presenter.bpf.c | 6 +-
drivers/hid/bpf/progs/Huion__Kamvas-Pro-19.bpf.c | 9 +-
.../hid/bpf/progs/IOGEAR__Kaliber-MMOmentum.bpf.c | 6 +-
drivers/hid/bpf/progs/Makefile | 2 +-
.../hid/bpf/progs/Microsoft__XBox-Elite-2.bpf.c | 6 +-
drivers/hid/bpf/progs/Wacom__ArtPen.bpf.c | 6 +-
drivers/hid/bpf/progs/XPPen__Artist24.bpf.c | 10 +-
drivers/hid/bpf/progs/XPPen__ArtistPro16Gen2.bpf.c | 24 +-
drivers/hid/bpf/progs/hid_bpf.h | 5 +
drivers/hid/hid-core.c | 6 +-
include/linux/hid_bpf.h | 125 ++---
samples/hid/Makefile | 5 +-
samples/hid/hid_bpf_attach.bpf.c | 18 -
samples/hid/hid_bpf_attach.h | 14 -
samples/hid/hid_mouse.bpf.c | 26 +-
samples/hid/hid_mouse.c | 39 +-
samples/hid/hid_surface_dial.bpf.c | 10 +-
samples/hid/hid_surface_dial.c | 53 +-
tools/testing/selftests/hid/hid_bpf.c | 100 +++-
tools/testing/selftests/hid/progs/hid.c | 100 +++-
.../testing/selftests/hid/progs/hid_bpf_helpers.h | 19 +-
32 files changed, 805 insertions(+), 1479 deletions(-)
---
base-commit: 70ec81c2e2b4005465ad0d042e90b36087c36104
change-id: 20240513-hid_bpf_struct_ops-e3212a224555

Best regards,
--
Benjamin Tissoires <bentiss@kernel.org>