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Merge branch 'generate-bpf_func_proto-for-kfunc'

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Amery Hung says:

====================
Generate bpf_func_proto for kfunc

Hi,

This is the second of three patch sets to unify kfunc and helper
argument verification. 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
====================

Link: https://patch.msgid.link/20260801074633.1595644-1-ameryhung@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
This commit is contained in:
Kumar Kartikeya Dwivedi 2026-08-03 00:29:19 +02:00
commit 8f876c773b
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