This patch set generalizes libbpf's CO-RE relocation support. In addition to existing field's byte offset relocation, libbpf now supports field existence relocations, which are emitted by Clang when using __builtin_preserve_field_info(<field>, BPF_FIELD_EXISTS). A convenience bpf_core_field_exists() macro is added to bpf_core_read.h BPF-side header, along the bpf_field_info_kind enum containing currently supported types of field information libbpf supports. This list will grow as libbpf gains support for other relo kinds.
This patch set upgrades the format of .BTF.ext's relocation record to match latest Clang's format (12 -> 16 bytes). This is not a breaking change, as the previous format hasn't been released yet as part of official Clang version release. v1->v2: - unify bpf_field_info_kind enum and naming changes (Alexei); - added bpf_core_field_exists() to bpf_core_read.h. Andrii Nakryiko (5): libbpf: update BTF reloc support to latest Clang format libbpf: refactor bpf_object__open APIs to use common opts libbpf: add support for field existance CO-RE relocation libbpf: add BPF-side definitions of supported field relocation kinds selftests/bpf: add field existence CO-RE relocs tests tools/lib/bpf/bpf_core_read.h | 24 ++- tools/lib/bpf/btf.c | 16 +- tools/lib/bpf/btf.h | 4 +- tools/lib/bpf/libbpf.c | 169 +++++++++++------- tools/lib/bpf/libbpf.h | 4 +- tools/lib/bpf/libbpf_internal.h | 25 ++- .../selftests/bpf/prog_tests/core_reloc.c | 76 +++++++- .../bpf/progs/btf__core_reloc_existence.c | 3 + ...ore_reloc_existence___err_wrong_arr_kind.c | 3 + ...loc_existence___err_wrong_arr_value_type.c | 3 + ...ore_reloc_existence___err_wrong_int_kind.c | 3 + ..._core_reloc_existence___err_wrong_int_sz.c | 3 + ...ore_reloc_existence___err_wrong_int_type.c | 3 + ..._reloc_existence___err_wrong_struct_type.c | 3 + .../btf__core_reloc_existence___minimal.c | 3 + .../selftests/bpf/progs/core_reloc_types.h | 56 ++++++ .../bpf/progs/test_core_reloc_existence.c | 79 ++++++++ 17 files changed, 392 insertions(+), 85 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_existence.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_existence___err_wrong_arr_kind.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_existence___err_wrong_arr_value_type.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_existence___err_wrong_int_kind.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_existence___err_wrong_int_sz.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_existence___err_wrong_int_type.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_existence___err_wrong_struct_type.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_existence___minimal.c create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_existence.c -- 2.17.1
