[PATCH v2 bpf-next 0/6] BPF static linker: support static vars and maps

[Andrii Nakryiko <andrii@kernel.org>]

Deal with static variables and maps better to make them work with BPF skeleton
well. All static variables and maps are renamed in corresponding BTF
information so as to have an "<obj_name>.." prefix, which allows to
distinguish name-conflicting static entities between multiple linked files.

Also make libbpf support static maps properly. Previously static map reference
resulted in the most probably erroneous use of the very *first* defined map,
because it was the one with offset 0. Now static map references are resolved
properly and thus static maps are finally usable. BPF static linker already
supports static maps and no further changes are required, beyond variable
renaming.

Patch #1 adds missed documentation of the latest Clang dependency.

N.B. This patch set is based on top of patch set [0].

  [0] https://patchwork.kernel.org/project/netdevbpf/list/?series=472405&state=*

v1->v2:
  - rebased on top of v3 of BPF static linker extern support patch set;
  - dropped selftests doc update, which went into mentioned patch set;
  - added skip modifiers for .data/.bss which was missed on initial submission.

Andrii Nakryiko (6):
  bpftool: strip const/volatile/restrict modifiers from .bss and .data
    vars
  libbpf: rename static variables during linking
  libbpf: support static map definitions
  bpftool: handle transformed static map names in BPF skeleton
  selftests/bpf: extend linked_vars selftests with static variables
  selftests/bpf: extend linked_maps selftests with static maps

 tools/bpf/bpftool/gen.c                       |  40 +++---
 tools/lib/bpf/libbpf.c                        |   7 +-
 tools/lib/bpf/libbpf.h                        |  12 +-
 tools/lib/bpf/linker.c                        | 121 +++++++++++++++++-
 .../selftests/bpf/prog_tests/linked_maps.c    |  20 ++-
 .../selftests/bpf/prog_tests/linked_vars.c    |  12 +-
 .../selftests/bpf/prog_tests/skeleton.c       |   8 +-
 .../selftests/bpf/prog_tests/static_linked.c  |   8 +-
 .../selftests/bpf/progs/bpf_iter_test_kern4.c |   4 +-
 .../selftests/bpf/progs/linked_maps1.c        |  13 ++
 .../selftests/bpf/progs/linked_maps2.c        |  18 +++
 .../selftests/bpf/progs/linked_vars1.c        |   4 +-
 .../selftests/bpf/progs/linked_vars2.c        |   4 +-
 .../selftests/bpf/progs/test_check_mtu.c      |   4 +-
 .../selftests/bpf/progs/test_cls_redirect.c   |   4 +-
 .../bpf/progs/test_snprintf_single.c          |   2 +-
 .../selftests/bpf/progs/test_sockmap_listen.c |   4 +-
 .../selftests/bpf/progs/test_static_linked1.c |   6 +-
 .../selftests/bpf/progs/test_static_linked2.c |   4 +-
 19 files changed, 244 insertions(+), 51 deletions(-)

-- 
2.30.2