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It: 1) further aligns the kfunc and helper argument checks, 2) makes kfunc argument type classification depend solely on BTF, and 3) generates a bpf_func_proto for each kfunc. With classification now a pure function of the kfunc's BTF, it is computed once at add-call time and cached in the generated bpf_func_proto, rather than re-derived on every verification of the call. Along the way it also fixes a few issues. The next patch set will align the argument register compatibility checks and route helper and kfunc argument verification through a single shared function. [1/3] https://lore.kernel.org/bpf/20260715064047.1793790-1-ameryhung@gmail.com/ Changelog v2 -> v3: - Drop a patch that introduces SCALAR_MAYBE_ZERO (Eduard) - Drop patch make helper handle mem+size at mem arg, and instead make kfunc also handle mem+size at size - patch 5: New patch replacing temporary mark_ptr_not_null_reg hack with refine_ptr_not_null_reg (Eduard) - patch 8: Only allow global subprog to read poisoned stack slots (Eduard) - patch 11: Test a precision gap when passing NULL to nullable-mem + size arg (Eduard) - patch 15: Reorganize BTF_ID, MEM, MEM+SIZE classification for clarity (Eduard) - patch 18: Emded bpf_func_proto in bpf_kfunc_desc and dynamically resize bpf_kfunc_desc_tab; Record saved_dst_prog_type early in bpf_prog_load to avoid introducing a fallback logic in resolve_prog_type (Eduard) Link: https://lore.kernel.org/bpf/20260724190813.1458271-1-ameryhung@gmail.com/ v1 -> v2: - patch 2: use reg_arg_name() for the map-mismatch message; derive the object register correctly on both helper and kfunc paths - patch 3: reject non-CONST_PTR_TO_MAP regs (base_type check) to fix map-value type confusion - patch 15: also reject referenced regs with unsafe modifiers (e.g. MEM_PERCPU) - patch 17: reject non-SCALAR_VALUE for KF_ARG_MEM_SIZE Amery Hung (17): bpf: Drop process_timer_func wrappers bpf: Unify const map ptr argument checking for helpers and kfuncs bpf: Split kfunc map argument into __const_map and __map bpf: Pass kfunc meta to mem and mem_size check bpf: Check helper and kfunc mem+size arguments identically selftests/bpf: Test map lookup result refinement bpf: Check fixed-size mem args of helpers and kfuncs the same way bpf: Rename ARG_CONST_SIZE{,_OR_ZERO} to ARG_MEM_SIZE{,_OR_ZERO} bpf: Fold __szk const size handling into the scalar arg path selftests/bpf: Test __szk precision with a NULL nullable buffer bpf: Classify kfunc mem_size args from BTF without register state bpf: Handle NULL kfunc pointer args without a KF_ARG_PTR_TO_NULL type bpf: Distinguish fixed- and variable-size kfunc mem args with MEM_FIXED_SIZE bpf: Classify kfunc pointer arguments from BTF, resolve type against the register bpf: Tag nullable kfunc pointer args with PTR_MAYBE_NULL bpf: Classify scalar kfunc arguments from BTF bpf: Generate kfunc argument prototype at add-call time Eduard Zingerman (1): bpf: Resolve map lookup result type at lookup time Documentation/bpf/kfuncs.rst | 30 +- include/linux/bpf.h | 40 +- include/linux/bpf_verifier.h | 22 +- kernel/bpf/backtrack.c | 2 +- kernel/bpf/bpf_lsm.c | 4 +- kernel/bpf/btf.c | 2 +- kernel/bpf/cgroup.c | 8 +- kernel/bpf/helpers.c | 42 +- kernel/bpf/ringbuf.c | 2 +- kernel/bpf/stackmap.c | 10 +- kernel/bpf/syscall.c | 8 +- kernel/bpf/verifier.c | 830 ++++++++++-------- kernel/trace/bpf_trace.c | 62 +- net/core/filter.c | 116 +-- .../selftests/bpf/prog_tests/verifier.c | 4 + .../selftests/bpf/progs/cgrp_kfunc_failure.c | 2 +- .../testing/selftests/bpf/progs/dynptr_fail.c | 2 +- .../bpf/progs/mem_rdonly_untrusted.c | 2 +- .../selftests/bpf/progs/task_kfunc_failure.c | 2 +- .../selftests/bpf/progs/verifier_bounds.c | 2 +- .../progs/verifier_helper_access_var_len.c | 6 +- .../bpf/progs/verifier_helper_value_access.c | 2 +- .../selftests/bpf/progs/verifier_map_in_map.c | 2 +- .../bpf/progs/verifier_map_lookup_refine.c | 73 ++ .../bpf/progs/verifier_mem_size_reg.c | 28 + .../selftests/bpf/progs/verifier_vfs_reject.c | 6 +- tools/testing/selftests/bpf/verifier/calls.c | 6 +- 27 files changed, 766 insertions(+), 549 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/verifier_map_lookup_refine.c create mode 100644 tools/testing/selftests/bpf/progs/verifier_mem_size_reg.c -- 2.52.0