[PATCH v2 bpf-next 00/12] CO-RE offset relocations

Andrii Nakryiko
2019-07-30T19:54:36Z

This patch set implements central part of CO-RE (Compile Once - Run
Everywhere, see [0] and [1] for slides and video): relocating fields offsets.
Most of the details are written down as comments to corresponding parts of the
code.

Patch #1 adds loading of .BTF.ext offset relocations section and macros to
work with its contents.
Patch #2 implements CO-RE relocations algorithm in libbpf.
Patch #3 introduced BPF_CORE_READ macro, hiding usage of Clang's
__builtin_preserve_access_index intrinsic that records offset relocation.
Patches #4-#12 adds selftests validating various parts of relocation handling,
type compatibility, etc.

For all tests to work, you'll need latest Clang/LLVM supporting
__builtin_preserve_access_index intrinsic, used for recording offset
relocations. Kernel on which selftests run should have BTF information built
in (CONFIG_DEBUG_INFO_BTF=y).

[0] http://vger.kernel.org/bpfconf2019.html#session-2
[1] http://vger.kernel.org/lpc-bpf2018.html#session-2

v1->v2:
- add offsetofend(), fix btf_ext optional fields checks (Song);
- add bpf_core_dump_spec() for logging spec representation;
- move special first element processing out of the loop (Song);
- typo fixes (Song);
- drop BPF_ST | BPF_MEM insn relocation (Alexei);
- extracted BPF_CORE_READ into bpf_helpers (Alexei);
- added extra tests validating Clang capturing relocs correctly (Yonghong);
- switch core_relocs.c to use sub-tests;
- updated mods tests after Clang bug was fixed (Yonghong);
- fix bug enumerating candidate types;

Andrii Nakryiko (12):
libbpf: add .BTF.ext offset relocation section loading
libbpf: implement BPF CO-RE offset relocation algorithm
selftests/bpf: add BPF_CORE_READ relocatable read macro
selftests/bpf: add CO-RE relocs testing setup
selftests/bpf: add CO-RE relocs struct flavors tests
selftests/bpf: add CO-RE relocs nesting tests
selftests/bpf: add CO-RE relocs array tests
selftests/bpf: add CO-RE relocs enum/ptr/func_proto tests
selftests/bpf: add CO-RE relocs modifiers/typedef tests
selftests/bpf: add CO-RE relocs ptr-as-array tests
selftests/bpf: add CO-RE relocs ints tests
selftests/bpf: add CO-RE relocs misc tests

tools/lib/bpf/btf.c | 69 +-
tools/lib/bpf/btf.h | 4 +
tools/lib/bpf/libbpf.c | 915 +++++++++++++++++-
tools/lib/bpf/libbpf.h | 1 +
tools/lib/bpf/libbpf_internal.h | 105 ++
tools/testing/selftests/bpf/bpf_helpers.h | 19 +
.../selftests/bpf/prog_tests/core_reloc.c | 381 ++++++++
.../bpf/progs/btf__core_reloc_arrays.c | 3 +
.../btf__core_reloc_arrays___diff_arr_dim.c | 3 +
...btf__core_reloc_arrays___diff_arr_val_sz.c | 3 +
.../btf__core_reloc_arrays___err_non_array.c | 3 +
...btf__core_reloc_arrays___err_too_shallow.c | 3 +
.../btf__core_reloc_arrays___err_too_small.c | 3 +
..._core_reloc_arrays___err_wrong_val_type1.c | 3 +
..._core_reloc_arrays___err_wrong_val_type2.c | 3 +
.../bpf/progs/btf__core_reloc_flavors.c | 3 +
.../btf__core_reloc_flavors__err_wrong_name.c | 3 +
.../bpf/progs/btf__core_reloc_ints.c | 3 +
.../bpf/progs/btf__core_reloc_ints___bool.c | 3 +
.../btf__core_reloc_ints___err_bitfield.c | 3 +
.../btf__core_reloc_ints___err_wrong_sz_16.c | 3 +
.../btf__core_reloc_ints___err_wrong_sz_32.c | 3 +
.../btf__core_reloc_ints___err_wrong_sz_64.c | 3 +
.../btf__core_reloc_ints___err_wrong_sz_8.c | 3 +
.../btf__core_reloc_ints___reverse_sign.c | 3 +
.../bpf/progs/btf__core_reloc_misc.c | 4 +
.../bpf/progs/btf__core_reloc_mods.c | 3 +
.../progs/btf__core_reloc_mods___mod_swap.c | 3 +
.../progs/btf__core_reloc_mods___typedefs.c | 3 +
.../bpf/progs/btf__core_reloc_nesting.c | 3 +
.../btf__core_reloc_nesting___anon_embed.c | 3 +
...f__core_reloc_nesting___dup_compat_types.c | 5 +
...core_reloc_nesting___err_array_container.c | 3 +
...tf__core_reloc_nesting___err_array_field.c | 3 +
...e_reloc_nesting___err_dup_incompat_types.c | 4 +
...re_reloc_nesting___err_missing_container.c | 3 +
...__core_reloc_nesting___err_missing_field.c | 3 +
..._reloc_nesting___err_nonstruct_container.c | 3 +
...e_reloc_nesting___err_partial_match_dups.c | 4 +
.../btf__core_reloc_nesting___err_too_deep.c | 3 +
.../btf__core_reloc_nesting___extra_nesting.c | 3 +
..._core_reloc_nesting___struct_union_mixup.c | 3 +
.../bpf/progs/btf__core_reloc_primitives.c | 3 +
...f__core_reloc_primitives___diff_enum_def.c | 3 +
..._core_reloc_primitives___diff_func_proto.c | 3 +
...f__core_reloc_primitives___diff_ptr_type.c | 3 +
...tf__core_reloc_primitives___err_non_enum.c | 3 +
...btf__core_reloc_primitives___err_non_int.c | 3 +
...btf__core_reloc_primitives___err_non_ptr.c | 3 +
.../bpf/progs/btf__core_reloc_ptr_as_arr.c | 3 +
.../btf__core_reloc_ptr_as_arr___diff_sz.c | 3 +
.../selftests/bpf/progs/core_reloc_types.h | 667 +++++++++++++
.../bpf/progs/test_core_reloc_arrays.c | 55 ++
.../bpf/progs/test_core_reloc_flavors.c | 62 ++
.../bpf/progs/test_core_reloc_ints.c | 44 +
.../bpf/progs/test_core_reloc_kernel.c | 36 +
.../bpf/progs/test_core_reloc_misc.c | 58 ++
.../bpf/progs/test_core_reloc_mods.c | 62 ++
.../bpf/progs/test_core_reloc_nesting.c | 46 +
.../bpf/progs/test_core_reloc_primitives.c | 43 +
.../bpf/progs/test_core_reloc_ptr_as_arr.c | 30 +
61 files changed, 2685 insertions(+), 49 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/core_reloc.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_arrays.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_arrays___diff_arr_dim.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_arrays___diff_arr_val_sz.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_arrays___err_non_array.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_arrays___err_too_shallow.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_arrays___err_too_small.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_arrays___err_wrong_val_type1.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_arrays___err_wrong_val_type2.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_flavors.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_flavors__err_wrong_name.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ints.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ints___bool.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ints___err_bitfield.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ints___err_wrong_sz_16.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ints___err_wrong_sz_32.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ints___err_wrong_sz_64.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ints___err_wrong_sz_8.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ints___reverse_sign.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_misc.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_mods.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_mods___mod_swap.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_mods___typedefs.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___anon_embed.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___dup_compat_types.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___err_array_container.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___err_array_field.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___err_dup_incompat_types.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___err_missing_container.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___err_missing_field.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___err_nonstruct_container.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___err_partial_match_dups.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___err_too_deep.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___extra_nesting.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_nesting___struct_union_mixup.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_primitives.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_primitives___diff_enum_def.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_primitives___diff_func_proto.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_primitives___diff_ptr_type.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_primitives___err_non_enum.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_primitives___err_non_int.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_primitives___err_non_ptr.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ptr_as_arr.c
create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_ptr_as_arr___diff_sz.c
create mode 100644 tools/testing/selftests/bpf/progs/core_reloc_types.h
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_arrays.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_flavors.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_ints.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_misc.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_mods.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_nesting.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_primitives.c
create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_ptr_as_arr.c

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2.17.1