Merge branch 'bpf-arm64-add-support-for-bpf-arena'

Puranjay Mohan says:

====================
bpf,arm64: Add support for BPF Arena

Changes in V4
V3: https://lore.kernel.org/bpf/20240323103057.26499-1-puranjay12@gmail.com/
- Use more descriptive variable names.
- Use insn_is_cast_user() helper.

Changes in V3
V2: https://lore.kernel.org/bpf/20240321153102.103832-1-puranjay12@gmail.com/
- Optimize bpf_addr_space_cast as suggested by Xu Kuohai

Changes in V2
V1: https://lore.kernel.org/bpf/20240314150003.123020-1-puranjay12@gmail.com/
- Fix build warnings by using 5 in place of 32 as DONT_CLEAR marker.
  R5 is not mapped to any BPF register so it can safely be used here.

This series adds the support for PROBE_MEM32 and bpf_addr_space_cast
instructions to the ARM64 BPF JIT. These two instructions allow the
enablement of BPF Arena.

All arena related selftests are passing.

  [root@ip-172-31-6-62 bpf]# ./test_progs -a "*arena*"
  #3/1     arena_htab/arena_htab_llvm:OK
  #3/2     arena_htab/arena_htab_asm:OK
  #3       arena_htab:OK
  #4/1     arena_list/arena_list_1:OK
  #4/2     arena_list/arena_list_1000:OK
  #4       arena_list:OK
  #434/1   verifier_arena/basic_alloc1:OK
  #434/2   verifier_arena/basic_alloc2:OK
  #434/3   verifier_arena/basic_alloc3:OK
  #434/4   verifier_arena/iter_maps1:OK
  #434/5   verifier_arena/iter_maps2:OK
  #434/6   verifier_arena/iter_maps3:OK
  #434     verifier_arena:OK
  Summary: 3/10 PASSED, 0 SKIPPED, 0 FAILED

This will need the patch [1] that introduced insn_is_cast_user() helper to
build.

The verifier_arena selftest could fail in the CI because the following
commit[2] is missing from bpf-next:

[1] https://lore.kernel.org/bpf/20240324183226.29674-1-puranjay12@gmail.com/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=fa3550dca8f02ec312727653a94115ef3ab68445

Here is a CI run with all dependencies added: https://github.com/kernel-patches/bpf/pull/6641
====================

Link: https://lore.kernel.org/r/20240325150716.4387-1-puranjay12@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>