| Message ID | 20240528-hid_bpf_struct_ops-v1-0-8c6663df27d8@kernel.org |
|---|---|
| Headers | show |
| Series | HID: convert HID-BPF into using bpf_struct_ops | expand |
On Wed, May 29, 2024 at 12:38 AM Benjamin Tissoires <bentiss@kernel.org> wrote: > > > Take a look at include/linux/bpf_mprog.h > > I suspect it might be useful here too. > > From the quick look of it this is interesting, but for plain struct > bpf_prog, right? > > So I would have to adapt this include for struct_ops? yeah. It needs work to be adapted to work with struct-ops. I mentioned it mainly from uapi perspective. BPF_F_BEFORE, BPF_F_AFTER, BPF_F_REPLACE. Would be good to keep things consistent. > > > @@ -112,6 +113,63 @@ struct hid_ops { > > > > > > extern struct hid_ops *hid_ops; > > > > > > +/** > > > + * struct hid_bpf_ops - A BPF struct_ops of callbacks allowing to attach HID-BPF > > > + * programs to a HID device > > > + * @hid_id: the HID uniq ID to attach to. This is writeable before ``load()``, and > > > + * cannot be changed after > > > + * @flags: &enum hid_bpf_attach_flags to assign flags before ``load()``. > > > + * Writeable only before ``load()`` > > > + */ > > > +struct hid_bpf_ops { > > > + /* hid_id needs to stay first so we can easily change it > > > + * from userspace. > > > + */ > > > > hmm. > > patch 5 just does: > > + skel->struct_ops.mouse_invert->hid_id = hid_id; > > > > I don't see a reason why it needs to be first. > > See the selftests (and my external loader, udev-hid-bpf): > > map = bpf_object__find_map_by_name(*self->skel->skeleton->obj, > programs[i].name + 4); > ASSERT_OK_PTR(map) TH_LOG("can not find struct_ops by name '%s'", > programs[i].name + 4); > > /* hid_id is the first field of struct hid_bpf_ops */ > ops_hid_id = bpf_map__initial_value(map, NULL); > ASSERT_OK_PTR(ops_hid_id) TH_LOG("unable to retrieve struct_ops data"); > > *ops_hid_id = self->hid_id; > > Basically, I want to have to deal with .bpf.o and not the skeletons for > the generic case. I want to be able to drop a file in /lib/firmware/hid > and have udev-hid-bpf load it without having to recompile udev-hid-bpf. and with additional restriction of only one struct-ops prog per elf file, right? Otherwise multiple hid_bpf_ops will be in the same elf section and the same map. > I couldn't seem to be able to access the struct_ops BTF information from > libbpf, so I decided to have hid_id and flags first and consider this to > be ABI while I figure out how to get to the real offsets :) I see. I guess it's ok for now.
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> --- Benjamin Tissoires (13): 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 Documentation/hid/hid-bpf.rst | 162 +++--- 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 | 246 +++++++++ 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 | 109 ++-- 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 +++- 31 files changed, 744 insertions(+), 1442 deletions(-) --- base-commit: 70ec81c2e2b4005465ad0d042e90b36087c36104 change-id: 20240513-hid_bpf_struct_ops-e3212a224555 Best regards,