This patch set adds BTF-to-C dumping APIs to libbpf, allowing to output a subset of BTF types as a compilable C type definitions. This is useful by itself, as raw BTF output is not easy to inspect and comprehend. But it's also a big part of BPF CO-RE (compile once - run everywhere) initiative aimed at allowing to write relocatable BPF programs, that won't require on-the-host kernel headers (and would be able to inspect internal kernel structures, not exposed through kernel headers). This patch set consists of three groups of patches and one pre-patch, with the BTF-to-C dumper API depending on the first two groups. Pre-patch #1 fixes issue with libbpf_internal.h. btf__parse_elf() API patches: - patch #2 adds btf__parse_elf() API to libbpf, allowing to load BTF and/or BTF.ext from ELF file; - patch #3 utilizies btf__parse_elf() from bpftool for `btf dump file` command; - patch #4 switches test_btf.c to use btf__parse_elf() to check for presence of BTF data in object file. libbpf's internal hashmap patches: - patch #5 adds resizeable non-thread safe generic hashmap to libbpf; - patch #6 adds tests for that hashmap; - patch #7 migrates btf_dedup()'s dedup_table to use hashmap w/ APPEND. BTF-to-C dumper API patches: - patch #8 adds btf_dump APIs with all the logic for laying out type definitions in correct order and emitting C syntax for them; - patch #9 adds lots of tests for common and quirky parts of C type system; - patch #10 adds support for C-syntax btf dumping to bpftool; - patch #11 updates bpftool documentation to mention C-syntax dump option; - patch #12 update bash-completion for btf dump sub-command. v0->v1: - fix bug in hashmap__for_each_bucket_entry() not handling empty hashmap; - removed `btf dump`-specific libbpf logging hook up (Quentin has more generic patchset); - change btf__parse_elf() to always load .BTF and return it as a result, with .BTF.ext being optional and returned through struct btf_ext** arg (Alexei); - endianness check to use __BYTE_ORDER__ (Alexei); - bool:1 to __u8:1 in type_aux_state (Alexei); - added HASHMAP_APPEND strategy to hashmap, changed hashmap__for_each_key_entry() to also check for key equality during iteration (multimap iteration for key); - added new tests for empty hashmap and hashmap as a multimap; - tried to clarify weak/strong dependency ordering comments (Alexei) - btf dump test's expected output - support better commenting aproach (Alexei); - added bash-completion for a new "c" option (Alexei). Andrii Nakryiko (12): libbpf: ensure libbpf.h is included along libbpf_internal.h libbpf: add btf__parse_elf API to load .BTF and .BTF.ext bpftool: use libbpf's btf__parse_elf API selftests/bpf: use btf__parse_elf to check presence of BTF/BTF.ext libbpf: add resizable non-thread safe internal hashmap selftests/bpf: add tests for libbpf's hashmap libbpf: switch btf_dedup() to hashmap for dedup table libbpf: add btf_dump API for BTF-to-C conversion selftests/bpf: add btf_dump BTF-to-C conversion tests bpftool: add C output format option to btf dump subcommand bpftool/docs: add description of btf dump C option bpftool: update bash-completion w/ new c option for btf dump .../bpf/bpftool/Documentation/bpftool-btf.rst | 5 +- tools/bpf/bpftool/bash-completion/bpftool | 22 +- tools/bpf/bpftool/btf.c | 150 +- tools/lib/bpf/Build | 4 +- tools/lib/bpf/btf.c | 330 ++-- tools/lib/bpf/btf.h | 19 + tools/lib/bpf/btf_dump.c | 1336 +++++++++++++++++ tools/lib/bpf/hashmap.c | 229 +++ tools/lib/bpf/hashmap.h | 173 +++ tools/lib/bpf/libbpf.map | 4 + tools/lib/bpf/libbpf_internal.h | 2 + tools/testing/selftests/bpf/.gitignore | 2 + tools/testing/selftests/bpf/Makefile | 3 +- .../bpf/progs/btf_dump_test_case_bitfields.c | 92 ++ .../bpf/progs/btf_dump_test_case_multidim.c | 35 + .../progs/btf_dump_test_case_namespacing.c | 73 + .../bpf/progs/btf_dump_test_case_ordering.c | 63 + .../bpf/progs/btf_dump_test_case_packing.c | 75 + .../bpf/progs/btf_dump_test_case_padding.c | 111 ++ .../bpf/progs/btf_dump_test_case_syntax.c | 229 +++ tools/testing/selftests/bpf/test_btf.c | 71 +- tools/testing/selftests/bpf/test_btf_dump.c | 143 ++ tools/testing/selftests/bpf/test_hashmap.c | 382 +++++ 23 files changed, 3275 insertions(+), 278 deletions(-) create mode 100644 tools/lib/bpf/btf_dump.c create mode 100644 tools/lib/bpf/hashmap.c create mode 100644 tools/lib/bpf/hashmap.h create mode 100644 tools/testing/selftests/bpf/progs/btf_dump_test_case_bitfields.c create mode 100644 tools/testing/selftests/bpf/progs/btf_dump_test_case_multidim.c create mode 100644 tools/testing/selftests/bpf/progs/btf_dump_test_case_namespacing.c create mode 100644 tools/testing/selftests/bpf/progs/btf_dump_test_case_ordering.c create mode 100644 tools/testing/selftests/bpf/progs/btf_dump_test_case_packing.c create mode 100644 tools/testing/selftests/bpf/progs/btf_dump_test_case_padding.c create mode 100644 tools/testing/selftests/bpf/progs/btf_dump_test_case_syntax.c create mode 100644 tools/testing/selftests/bpf/test_btf_dump.c create mode 100644 tools/testing/selftests/bpf/test_hashmap.c -- 2.17.1
