[v5,bpf-next,0/9] bpf: Add d_path helper - preparation changes

hi,
this patchset does preparation work for adding d_path helper,
which still needs more work, but the initial set of patches
is ready and useful to have.

This patchset adds:
  - support to generate BTF ID lists that are resolved during
    kernel linking and usable within kernel code with following
    macros:

      BTF_ID_LIST(bpf_skb_output_btf_ids)
      BTF_ID(struct, sk_buff)

    and access it in kernel code via:
      extern u32 bpf_skb_output_btf_ids[];

  - resolve_btfids tool that scans elf object for .BTF_ids
    section and resolves its symbols with BTF ID values
  - resolving of bpf_ctx_convert struct and several other
    objects with BTF_ID_LIST


v5 changes:
  - added acks to patches I did not change in this version
  - split the original patchset into 2 parts and sending the first one
    where the support to define BTF list is added, the BTF set support
    will be posted later on [Andrii]
  - used u32 instead of int in btf_ids.h [Andrii]
  - changed the btf_ids.h define guard [Andrii]
  - added resolve_btfids_clean target [Andrii]
  - moved resolve_btfids test into prog_tests suite [Andrii]
  - fixed BTF type iteration index in test [Andrii]
  - removed btf_id checks in bpf_ctx_convert resolve code [Yonghong]
  - removed WARN_ON_ONCE from btf_resolve_helper_id [Yonghong]
  - added BTF_ID_UNUSED macro [Yonghong]
  - fixed out of the tree build failure [0day bot]

Also available at:
  https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
  bpf/d_path

thanks,
jirka


---
Jiri Olsa (9):
      bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object
      bpf: Compile resolve_btfids tool at kernel compilation start
      bpf: Add BTF_ID_LIST/BTF_ID/BTF_ID_UNUSED macros
      bpf: Resolve BTF IDs in vmlinux image
      bpf: Remove btf_id helpers resolving
      bpf: Use BTF_ID to resolve bpf_ctx_convert struct
      bpf: Add info about .BTF.ids section to btf.rst
      tools headers: Adopt verbatim copy of btf_ids.h from kernel sources
      selftests/bpf: Add test for resolve_btfids

 Documentation/bpf/btf.rst                               |  36 +++++
 Makefile                                                |  25 +++-
 include/asm-generic/vmlinux.lds.h                       |   4 +
 include/linux/btf_ids.h                                 |  87 ++++++++++++
 kernel/bpf/btf.c                                        | 103 ++------------
 kernel/trace/bpf_trace.c                                |   9 +-
 net/core/filter.c                                       |   9 +-
 scripts/link-vmlinux.sh                                 |   6 +
 tools/Makefile                                          |   3 +
 tools/bpf/Makefile                                      |   9 +-
 tools/bpf/resolve_btfids/Build                          |  26 ++++
 tools/bpf/resolve_btfids/Makefile                       |  77 +++++++++++
 tools/bpf/resolve_btfids/main.c                         | 716 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/include/linux/btf_ids.h                           |  87 ++++++++++++
 tools/include/linux/compiler.h                          |   4 +
 tools/testing/selftests/bpf/Makefile                    |  22 ++-
 tools/testing/selftests/bpf/prog_tests/resolve_btfids.c | 170 +++++++++++++++++++++++
 17 files changed, 1289 insertions(+), 104 deletions(-)
 create mode 100644 include/linux/btf_ids.h
 create mode 100644 tools/bpf/resolve_btfids/Build
 create mode 100644 tools/bpf/resolve_btfids/Makefile
 create mode 100644 tools/bpf/resolve_btfids/main.c
 create mode 100644 tools/include/linux/btf_ids.h
 create mode 100644 tools/testing/selftests/bpf/prog_tests/resolve_btfids.c