bpf: Introduce global functions

Introduce static vs global functions and function by function verification.
This is another step toward dynamic re-linking (or replacement) of global
functions. See patch 3 for details. The rest are supporting patches.

Alexei Starovoitov (6):
  libbpf: Sanitize BTF_KIND_FUNC linkage
  libbpf: Collect static vs global info about functions
  bpf: Introduce function-by-function verification
  selftests/bpf: Add fexit-to-skb test for global funcs
  selftests/bpf: Add a test for a large global function
  selftests/bpf: Modify a test to check global functions

 include/linux/bpf.h                           |   7 +-
 include/linux/bpf_verifier.h                  |   7 +-
 include/uapi/linux/btf.h                      |   6 +
 kernel/bpf/btf.c                              | 147 ++++++++---
 kernel/bpf/verifier.c                         | 228 ++++++++++++++----
 tools/include/uapi/linux/btf.h                |   6 +
 tools/lib/bpf/libbpf.c                        | 150 +++++++++++-
 .../bpf/prog_tests/bpf_verif_scale.c          |   2 +
 .../selftests/bpf/prog_tests/fexit_bpf2bpf.c  |   1 +
 .../selftests/bpf/progs/fexit_bpf2bpf.c       |  15 ++
 tools/testing/selftests/bpf/progs/pyperf.h    |   9 +-
 .../selftests/bpf/progs/pyperf_global.c       |   5 +
 .../selftests/bpf/progs/test_pkt_access.c     |  28 +++
 .../selftests/bpf/progs/test_xdp_noinline.c   |   4 +-
 14 files changed, 528 insertions(+), 87 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/pyperf_global.c

-- 
2.23.0