Some BPF programs like scx schedulers have their own internal CPU mask types, mask types, which they must transform into struct bpf_cpumask instances before passing them to scheduling-related kfuncs. There is currently no way to efficiently populate the bitfield of a bpf_cpumask from BPF memory, and programs must use multiple bpf_cpumask_[set, clear] calls to do so. Introduce a kfunc helper to populate the bitfield of a bpf_cpumask from valid BPF memory with a single call. Changelog : ----------- v2->v3 v2: https://lore.kernel.org/bpf/20250305021020.1004858-1-emil@xxxxxxxxxxxxxxx/ Addressed feedback by Alexei Starovoitov: * Added back patch descriptions dropped from v1->v2 * Elide the alignment check for archs with efficient unaligned accesses v1->v2 v1: https://lore.kernel.org/bpf/20250228003321.1409285-1-emil@xxxxxxxxxxxxxxx/ Addressed feedback by Hou Tao: * Add check that the input buffer is aligned to sizeof(long) * Adjust input buffer size check to use bitmap_size() * Add selftest for checking the bit pattern of the bpf_cpumask * Moved all selftests into existing files Signed-off-by: Emil Tsalapatis (Meta) <emil@xxxxxxxxxxxxxxx> Emil Tsalapatis (2): bpf: add kfunc for populating cpumask bits selftests: bpf: add bpf_cpumask_fill selftests kernel/bpf/cpumask.c | 28 +++++ .../selftests/bpf/prog_tests/cpumask.c | 3 + .../selftests/bpf/progs/cpumask_failure.c | 38 ++++++ .../selftests/bpf/progs/cpumask_success.c | 114 ++++++++++++++++++ 4 files changed, 183 insertions(+) -- 2.47.1
