[bpf-next,v4,00/18] bpf: Add 64bit enum value support

Message

Yonghong Song June 3, 2022, 1:58 a.m. UTC

Currently, btf only supports upto 32bit enum value with BTF_KIND_ENUM.
But in kernel, some enum has 64bit values, e.g., in uapi bpf.h, we have
  enum {
        BPF_F_INDEX_MASK                = 0xffffffffULL,
        BPF_F_CURRENT_CPU               = BPF_F_INDEX_MASK,
        BPF_F_CTXLEN_MASK               = (0xfffffULL << 32),
  };
With BTF_KIND_ENUM, the value for BPF_F_CTXLEN_MASK will be encoded
as 0 which is incorrect.

To solve this problem, BTF_KIND_ENUM64 is proposed in this patch set
to support enum 64bit values. Also, since sometimes there is a need
to generate C code from btf, e.g., vmlinux.h, btf kflag support
is also added for BTF_KIND_ENUM and BTF_KIND_ENUM64 to indicate
signedness, helping proper value printout.

Changelog:
  v3 -> v4:
    - rename btf_type_is_any_enum() to btf_is_any_enum() to favor
      consistency in libbpf.
    - fix sign extension issue in btf_dump_get_enum_value().
    - fix BPF_CORE_FIELD_SIGNED signedness issue in bpf_core_calc_field_relo().
  v2 -> v3:
    - Implement separate btf_equal_enum()/btf_equal_enum64() and
      btf_compat_enum()/btf_compat_enum64().
    - Add a new enum64 placeholder type dynamicly for enum64 sanitization.
    - For bpftool output and unit selftest, printed out signed/unsigned
      encoding as well.
    - fix some issues with BTF_KIND_ENUM is doc and clarified sign extension
      rules for enum values.
  v1 -> v2:
    - Changed kflag default from signed to unsigned
    - Fixed sanitization issue
    - Broke down libbpf related patches for easier review
    - Added more tests
    - More code refactorization
    - Corresponding llvm patch (to support enum64) is also updated

Yonghong Song (18):
  bpf: Add btf enum64 support
  libbpf: Permit 64bit relocation value
  libbpf: Fix an error in 64bit relocation value computation
  libbpf: Refactor btf__add_enum() for future code sharing
  libbpf: Add enum64 parsing and new enum64 public API
  libbpf: Add enum64 deduplication support
  libbpf: Add enum64 support for btf_dump
  libbpf: Add enum64 sanitization
  libbpf: Add enum64 support for bpf linking
  libbpf: Add enum64 relocation support
  bpftool: Add btf enum64 support
  selftests/bpf: Fix selftests failure
  selftests/bpf: Test new enum kflag and enum64 API functions
  selftests/bpf: Add BTF_KIND_ENUM64 unit tests
  selftests/bpf: Test BTF_KIND_ENUM64 for deduplication
  selftests/bpf: Add a test for enum64 value relocations
  selftests/bpf: Clarify llvm dependency with possible selftest failures
  docs/bpf: Update documentation for BTF_KIND_ENUM64 support

 Documentation/bpf/btf.rst                     |  43 +++-
 include/linux/btf.h                           |  28 +++
 include/uapi/linux/btf.h                      |  17 +-
 kernel/bpf/btf.c                              | 142 +++++++++++--
 kernel/bpf/verifier.c                         |   2 +-
 tools/bpf/bpftool/btf.c                       |  57 ++++-
 tools/bpf/bpftool/btf_dumper.c                |  29 +++
 tools/bpf/bpftool/gen.c                       |   1 +
 tools/include/uapi/linux/btf.h                |  17 +-
 tools/lib/bpf/btf.c                           | 201 ++++++++++++++++--
 tools/lib/bpf/btf.h                           |  32 ++-
 tools/lib/bpf/btf_dump.c                      | 137 +++++++++---
 tools/lib/bpf/libbpf.c                        |  63 +++++-
 tools/lib/bpf/libbpf.map                      |   2 +
 tools/lib/bpf/libbpf_internal.h               |   2 +
 tools/lib/bpf/linker.c                        |   2 +
 tools/lib/bpf/relo_core.c                     | 105 +++++----
 tools/lib/bpf/relo_core.h                     |   4 +-
 tools/testing/selftests/bpf/README.rst        |  18 ++
 tools/testing/selftests/bpf/btf_helpers.c     |  25 ++-
 tools/testing/selftests/bpf/prog_tests/btf.c  | 153 +++++++++++--
 .../selftests/bpf/prog_tests/btf_write.c      | 126 ++++++++---
 .../selftests/bpf/prog_tests/core_reloc.c     |  58 +++++
 .../bpf/progs/btf__core_reloc_enum64val.c     |   3 +
 .../progs/btf__core_reloc_enum64val___diff.c  |   3 +
 .../btf__core_reloc_enum64val___err_missing.c |   3 +
 ...btf__core_reloc_enum64val___val3_missing.c |   3 +
 .../selftests/bpf/progs/core_reloc_types.h    |  78 +++++++
 .../bpf/progs/test_core_reloc_enum64val.c     |  70 ++++++
 tools/testing/selftests/bpf/test_btf.h        |   1 +
 30 files changed, 1235 insertions(+), 190 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_enum64val.c
 create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_enum64val___diff.c
 create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_enum64val___err_missing.c
 create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_enum64val___val3_missing.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_enum64val.c