[PATCH bpf-next v5 00/14] Add arena argument support to kfuncs and struct_ops

[Kumar Kartikeya Dwivedi <memxor@gmail.com>]

This is a continuation of patches in [0], with mostly minor changes and
reordering. The motivation is covered in that link. A major change is
moving to two tags (__arena and __arena__nullable) and moving the changes
to JIT to emit more optimized sequences.

Please see commit logs for details.

  [0]: https://lore.kernel.org/bpf/20260713024414.3759854-1-tj@kernel.org

Changelog:
----------
v4 -> v5
v4: https://lore.kernel.org/bpf/20260805210427.3218326-1-memxor@gmail.com

 * Remove the redundant patch-8 capability comment and duplicate
   nullable kfunc test coverage. (Eduard)
 * Introduce the final bpf_tramp_arena_base() interface directly with
   function-model argument flags, avoiding temporary slot bitmaps and
   arena_nullable state; simplify struct_ops pointer validation. (Eduard)
 * Simplify kfunc arena nullability classification by using the common
   nullable path for both arena suffixes while leaving the function model
   to distinguish JIT NULL preservation. (Amery)
 * Keep bpf_prog_has_arena_ctx_arg() in bpf_verifier.h from its
   introduction so trampoline and verifier users share one inline
   definition, avoiding BPF_JIT/BPF_SYSCALL link dependencies.
   (Eduard, BPF CI Bot)
 * Reject both tracing and extension attachments to struct_ops programs
   with arena context arguments, and add fentry, fexit, and freplace
   rejection tests. (Eduard, Sashiko)

v3 -> v4
v3: https://lore.kernel.org/bpf/20260803125115.2264733-1-memxor@gmail.com

 * Rename __arena_nullable to __arena__nullable and prioritize the
   composite suffix over __nullable during argument classification.
   (Sashiko, Eduard)
 * Resolve instructions before collecting subprograms and kfuncs so kfunc
   prototype validation can use associated arena state.
 * Move the arena kfunc and JIT-sequence test entry points into
   prog_tests/verifier.c. (Eduard)
 * Match the generated L0 target and call in nullable JIT assertions.
   (Eduard)
 * Route arena kfunc validation through the common argument-checking path.
   (Amery)
 * Reuse btf_func_model argument flags for struct_ops arena arguments
   instead of maintaining separate trampoline slot metadata. (Eduard)
 * Check the generic-trampoline arena argument invariant at link time and
   warn once on violations. (Eduard)
 * Reject tracing attachments to struct_ops programs with arena context
   arguments whose indirect trampolines convert the pointers. (Sashiko)

v2 -> v3
v2: https://lore.kernel.org/bpf/20260726013105.3689867-1-memxor@gmail.com

 * Rebase onto current bpf-next to resolve conflicts.

v1 -> v2
v1: https://lore.kernel.org/bpf/20260715220052.1590783-1-memxor@gmail.com

 * Fix documentation to only mention x86 for now. (Sashiko)
 * Move arg bitmap from insn_aux_data to kfunc descriptor. (Eduard)

Kumar Kartikeya Dwivedi (5):
  bpf: Rename 'early' BTF checking as a preparation phase
  bpf: Split subprogram and kfunc collection
  bpf: Collect kfuncs after resolving program resources
  bpf: Reject tracing/freplace progs for struct_ops with arena args
  selftests/bpf: Test attach rejection for struct_ops arena programs

Tejun Heo (9):
  bpf: Support __arena and __arena__nullable kfunc argument suffixes
  bpf: Support __arena and __arena__nullable on struct_ops arguments
  bpf, x86: JIT __arena kfunc argument rebasing
  bpf, x86: Convert struct_ops arena arguments in the trampoline
  selftests/bpf: Add kfunc __arena and __arena__nullable argument tests
  selftests/bpf: Add JIT-sequence tests for __arena kfunc arguments
  selftests/bpf: Add struct_ops __arena and __arena__nullable argument
    tests
  bpf, x86: Fix stack-passed arguments for indirect trampolines
  selftests/bpf: Test stack-passed struct_ops arena arguments

 Documentation/bpf/kfuncs.rst                  |  39 +++
 arch/x86/net/bpf_jit_comp.c                   | 122 ++++++++-
 include/linux/bpf.h                           |  15 ++
 include/linux/bpf_verifier.h                  |  14 +-
 include/linux/filter.h                        |   1 +
 kernel/bpf/bpf_struct_ops.c                   |  56 +++--
 kernel/bpf/btf.c                              |  28 ++-
 kernel/bpf/check_btf.c                        |  14 +-
 kernel/bpf/core.c                             |   5 +
 kernel/bpf/trampoline.c                       |  37 +++
 kernel/bpf/verifier.c                         | 125 ++++++++--
 .../bpf/prog_tests/test_struct_ops_arena.c    | 128 ++++++++++
 .../selftests/bpf/prog_tests/verifier.c       |   6 +
 .../testing/selftests/bpf/progs/arena_kfunc.c | 234 ++++++++++++++++++
 .../selftests/bpf/progs/arena_kfunc_jit.c     |  98 ++++++++
 .../selftests/bpf/progs/struct_ops_arena.c    | 115 +++++++++
 .../bpf/progs/struct_ops_arena_attach.c       |  25 ++
 .../bpf/progs/struct_ops_arena_fail.c         |  20 ++
 .../selftests/bpf/test_kmods/bpf_testmod.c    |  82 ++++++
 .../selftests/bpf/test_kmods/bpf_testmod.h    |   6 +
 .../bpf/test_kmods/bpf_testmod_kfunc.h        |  12 +
 21 files changed, 1123 insertions(+), 59 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_struct_ops_arena.c
 create mode 100644 tools/testing/selftests/bpf/progs/arena_kfunc.c
 create mode 100644 tools/testing/selftests/bpf/progs/arena_kfunc_jit.c
 create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_arena.c
 create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_arena_attach.c
 create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_arena_fail.c


base-commit: 51476f6a06ef55cecf785ae1622c638fa8cfb846
-- 
2.53.0-Meta