The BPF Type Format (BTF) can be used in conjunction with the helper bpf_snprintf_btf() to display kernel data with type information.
This series generalizes that support and shares it with libbpf so that libbpf can display typed data. BTF display functionality is factored out of kernel/bpf/btf.c into kernel/bpf/btf_show_common.c, and that file is duplicated in tools/lib/bpf. Similarly, common definitions and inline functions needed for this support are extracted into include/linux/btf_common.h and this header is again duplicated in tools/lib/bpf.
Patch 1 carries out the refactoring, for which no kernel changes are intended, and introduces btf__snprintf() a libbpf function that supports dumping a string representation of typed data using the struct btf * and id associated with that type.
Patch 2 tests btf__snprintf() with built-in and kernel types to ensure data is of expected format. The test closely mirrors the BPF program associated with the snprintf_btf.c; in this case however the string representations are verified in userspace rather than in BPF program context.
Alan Maguire (2): bpf: share BTF "show" implementation between kernel and libbpf selftests/bpf: test libbpf-based type display
include/linux/btf.h | 121 +- include/linux/btf_common.h | 286 +++++ kernel/bpf/Makefile | 2 +- kernel/bpf/arraymap.c | 1 + kernel/bpf/bpf_struct_ops.c | 1 + kernel/bpf/btf.c | 1215 +------------------ kernel/bpf/btf_show_common.c | 1218 ++++++++++++++++++++ kernel/bpf/core.c | 1 + kernel/bpf/hashtab.c | 1 + kernel/bpf/local_storage.c | 1 + kernel/bpf/verifier.c | 1 + kernel/trace/bpf_trace.c | 1 + tools/lib/bpf/Build | 2 +- tools/lib/bpf/btf.h | 7 + tools/lib/bpf/btf_common.h | 286 +++++ tools/lib/bpf/btf_show_common.c | 1218 ++++++++++++++++++++ tools/lib/bpf/libbpf.map | 1 + .../selftests/bpf/prog_tests/snprintf_btf_user.c | 192 +++ 18 files changed, 3236 insertions(+), 1319 deletions(-) create mode 100644 include/linux/btf_common.h create mode 100644 kernel/bpf/btf_show_common.c create mode 100644 tools/lib/bpf/btf_common.h create mode 100644 tools/lib/bpf/btf_show_common.c create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf_btf_user.c