[bpf-next,v4,0/7] IRQ save/restore

Message

Kumar Kartikeya Dwivedi Nov. 27, 2024, 9:35 p.m. UTC

This set introduces support for managing IRQ state from BPF programs.
Two new kfuncs, bpf_local_irq_save, and bpf_local_irq_restore are
introduced to enable this functionality.

Intended use cases are writing IRQ safe data structures (e.g. memory
allocator) in BPF programs natively, and use in new spin locking
primitives intended to be introduced in the next few weeks.

The set begins with some refactoring patches before the actual
functionality is introduced. Patch 1 consolidates all resource related
state in bpf_verifier_state, and moves it out from bpf_func_state.

Patch 2 refactor acquire and release functions for reference state to
make them reusable without duplication for other resource types.

After this, patch 3 refactors stack slot liveness marking logic to be
shared between dynptr, and iterators, in preparation for introducing
same logic for irq flag object on stack.

Finally, patch 4 and 7 introduce the new kfuncs and their selftests. For
more details, please inspect the patch commit logs. Patch 5 makes the
error message in case of resource leaks under BPF_EXIT a bit clearer.
Patch 6 expands coverage of existing preempt-disable selftest to cover
sleepable kfuncs.

See individual patches for more details.

Changelog:
----------
v3 -> v4
v3: https://lore.kernel.org/bpf/[e-mail]

 * Add yet another missing kfunc declaration to silence s390 CI

v2 -> v3
v2: https://lore.kernel.org/bpf/[e-mail]

 * Drop REF_TYPE_LOCK_MASK
 * Add kfunc declarations to selftest to silence s390 CI errors

v1 -> v2
v1: https://lore.kernel.org/bpf/[e-mail]

 * Drop reference -> resource renaming in the verifier (Eduard, Alexei)
 * Change verifier log for check_resource_leak for BPF_EXIT (Eduard)
 * Remove id parameter from acquire_resource_state, read s->id (Eduard)
 * Rename erase to release for reference state (Eduard)
 * Move resource state to bpf_verifier_state (Eduard, Alexei)
 * Drop unnecessary casting to/from u64 in helpers (Eduard)
 * Add test for arg != PTR_TO_STACK (Eduard)
 * Drop now redundant tests (Eduard)
 * Address some other misc nits
 * Add Reviewed-by and Acked-by from Eduard

Kumar Kartikeya Dwivedi (7):
  bpf: Consolidate locks and reference state in verifier state
  bpf: Refactor {acquire,release}_reference_state
  bpf: Refactor mark_{dynptr,iter}_read
  bpf: Introduce support for bpf_local_irq_{save,restore}
  bpf: Improve verifier log for resource leak on exit
  selftests/bpf: Expand coverage of preempt tests to sleepable kfunc
  selftests/bpf: Add IRQ save/restore tests

 include/linux/bpf_verifier.h                  |  19 +-
 kernel/bpf/helpers.c                          |  17 +
 kernel/bpf/log.c                              |  12 +-
 kernel/bpf/verifier.c                         | 531 +++++++++++++-----
 .../selftests/bpf/prog_tests/verifier.c       |   2 +
 .../selftests/bpf/progs/exceptions_fail.c     |   4 +-
 tools/testing/selftests/bpf/progs/irq.c       | 397 +++++++++++++
 .../selftests/bpf/progs/preempt_lock.c        |  28 +-
 .../selftests/bpf/progs/verifier_spin_lock.c  |   2 +-
 9 files changed, 865 insertions(+), 147 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/irq.c


base-commit: c8d02b547363880d996f80c38cc8b997c7b90725
prerequisite-patch-id: 39c773cdece7c5fee2459d6825c8aef069381581