Hi,
So this is the fix for the bug that actually prevented me to integrate
HID-BPF in v6.2.
While testing the code base with LLVM, I realized that clang was smarter
than I expected it to be, and it sometimes inlined a function or not
depending on the branch. This lead to segfaults because my current code
in linux-next is messing up the bpf programs refcounts assuming that I
had enough observability over the kernel.
So I came back to the drawing board and realized that what I was missing
was exactly a bpf_link, to represent the attachment of a bpf program to
a HID device. This is the bulk of the series, in patch 6/9.
The other patches are cleanups, tests, and also the addition of the
vmtests.sh script I run locally, largely inspired by the one in the bpf
selftests dir. This allows very fast development of HID-BPF, assuming we
have tests that cover the bugs :)
changes in v2:
- took Alexei's remarks into account and renamed the indexes into
prog_table_index and hid_table_index
- fixed unused function as reported by the Intel kbuild bot
Cheers,
Benjamin
Benjamin Tissoires (9):
selftests: hid: add vmtest.sh
selftests: hid: allow to compile hid_bpf with LLVM
selftests: hid: attach/detach 2 bpf programs, not just one
selftests: hid: ensure the program is correctly pinned
selftests: hid: prepare tests for HID_BPF API change
HID: bpf: rework how programs are attached and stored in the kernel
selftests: hid: enforce new attach API
HID: bpf: clean up entrypoint
HID: bpf: reorder BPF registration
Documentation/hid/hid-bpf.rst | 12 +-
drivers/hid/bpf/entrypoints/entrypoints.bpf.c | 9 -
.../hid/bpf/entrypoints/entrypoints.lskel.h | 188 ++++--------
drivers/hid/bpf/hid_bpf_dispatch.c | 28 +-
drivers/hid/bpf/hid_bpf_dispatch.h | 3 -
drivers/hid/bpf/hid_bpf_jmp_table.c | 129 ++++----
include/linux/hid_bpf.h | 7 +
tools/testing/selftests/hid/.gitignore | 1 +
tools/testing/selftests/hid/Makefile | 10 +-
tools/testing/selftests/hid/config.common | 241 +++++++++++++++
tools/testing/selftests/hid/config.x86_64 | 4 +
tools/testing/selftests/hid/hid_bpf.c | 32 +-
tools/testing/selftests/hid/progs/hid.c | 13 +
tools/testing/selftests/hid/vmtest.sh | 284 ++++++++++++++++++
14 files changed, 728 insertions(+), 233 deletions(-)
create mode 100644 tools/testing/selftests/hid/config.common
create mode 100644 tools/testing/selftests/hid/config.x86_64
create mode 100755 tools/testing/selftests/hid/vmtest.sh
--
2.38.1
On Fri, 13 Jan 2023, Benjamin Tissoires wrote:
> Hi,
>
> So this is the fix for the bug that actually prevented me to integrate
> HID-BPF in v6.2.
>
> While testing the code base with LLVM, I realized that clang was smarter
> than I expected it to be, and it sometimes inlined a function or not
> depending on the branch. This lead to segfaults because my current code
> in linux-next is messing up the bpf programs refcounts assuming that I
> had enough observability over the kernel.
>
> So I came back to the drawing board and realized that what I was missing
> was exactly a bpf_link, to represent the attachment of a bpf program to
> a HID device. This is the bulk of the series, in patch 6/9.
>
> The other patches are cleanups, tests, and also the addition of the
> vmtests.sh script I run locally, largely inspired by the one in the bpf
> selftests dir. This allows very fast development of HID-BPF, assuming we
> have tests that cover the bugs :)
>
>
> changes in v2:
> - took Alexei's remarks into account and renamed the indexes into
> prog_table_index and hid_table_index
> - fixed unused function as reported by the Intel kbuild bot
I've now applied this on top of the previous work in
hid.git#for-6.3/hid-bpf
--
Jiri Kosina
SUSE Labs