bpf: Prep patches for static stack liveness.

From: Alexei Starovoitov <ast@kernel.org>

First 6 prep patches for static stack liveness.

. do src/dst_reg validation early and remove defensive checks

. sort subprog in topo order. We wanted to do this long ago
  to process global subprogs this way and in other cases.

. Add constant folding pass that computes map_ptr, subprog_idx,
  loads from readonly maps, and other constants that fit into 32-bit

. Use these constants to eliminate dead code. Replace predicted
  conditional branches with "jmp always". That reduces JIT prog size.

. Add two helpers that return access size from their arguments.

Alexei Starovoitov (6):
  bpf: Do register range validation early
  bpf: Sort subprogs in topological order after check_cfg()
  selftests/bpf: Add tests for subprog topological ordering
  bpf: Add compute_const_regs() and prune_dead_branches() passes
  bpf: Move verifier helpers to header
  bpf: Add helper and kfunc stack access size resolution

 include/linux/bpf_verifier.h                  |  61 +++
 kernel/bpf/Makefile                           |   2 +-
 kernel/bpf/const_fold.c                       | 385 ++++++++++++++++++
 kernel/bpf/verifier.c                         | 373 ++++++++++++++---
 .../selftests/bpf/prog_tests/verifier.c       |   2 +
 .../selftests/bpf/progs/verifier_scalar_ids.c |  20 +-
 .../bpf/progs/verifier_subprog_topo.c         | 226 ++++++++++
 7 files changed, 1000 insertions(+), 69 deletions(-)
 create mode 100644 kernel/bpf/const_fold.c
 create mode 100644 tools/testing/selftests/bpf/progs/verifier_subprog_topo.c

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2.52.0