[v7,bpf-next,0/2] bpf: Add a generic bits iterator

Message

Yafang Shao May 6, 2024, 3:33 a.m. UTC

hree new kfuncs, namely bpf_iter_bits_{new,next,destroy}, have been
added for the new bpf_iter_bits functionality. These kfuncs enable the
iteration of the bits from a given address and a given number of bits.

- bpf_iter_bits_new
  Initialize a new bits iterator for a given memory area. Due to the
  limitation of bpf memalloc, the max number of bits to be iterated
  over is (4096 * 8).
- bpf_iter_bits_next
  Get the next bit in a bpf_iter_bits
- bpf_iter_bits_destroy
  Destroy a bpf_iter_bits

The bits iterator can be used in any context and on any address.

Changes:
- v6->v7:
  - Fix endianness error for non-long-aligned data (Andrii)
- v5->v6:
  - Add positive tests (Andrii)
- v4->v5:
  - Simplify test cases (Andrii)
- v3->v4:
  - Fix endianness error on s390x (Andrii)
  - zero-initialize kit->bits_copy and zero out nr_bits (Andrii)
- v2->v3:
  - Optimization for u64/u32 mask (Andrii)
- v1->v2:
  - Simplify the CPU number verification code to avoid the failure on s390x
    (Eduard)
- bpf: Add bpf_iter_cpumask
  https://lwn.net/Articles/961104/
- bpf: Add new bpf helper bpf_for_each_cpu
  https://lwn.net/Articles/939939/

Yafang Shao (2):
  bpf: Add bits iterator
  selftests/bpf: Add selftest for bits iter

 kernel/bpf/helpers.c                          | 140 +++++++++++++++
 .../selftests/bpf/prog_tests/verifier.c       |   2 +
 .../selftests/bpf/progs/verifier_bits_iter.c  | 160 ++++++++++++++++++
 3 files changed, 302 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/verifier_bits_iter.c