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Message-ID: <FCAF9AD8-C138-4AA7-AD68-195B01C6A25C@fb.com>
Date: Tue, 30 Jul 2019 05:27:55 +0000
From: Song Liu <songliubraving@...com>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
CC: Song Liu <liu.song.a23@...il.com>,
Andrii Nakryiko <andriin@...com>, bpf <bpf@...r.kernel.org>,
Networking <netdev@...r.kernel.org>,
"Alexei Starovoitov" <ast@...com>,
Daniel Borkmann <daniel@...earbox.net>,
"Yonghong Song" <yhs@...com>, Kernel Team <Kernel-team@...com>
Subject: Re: [PATCH bpf-next 00/10] CO-RE offset relocations
> On Jul 29, 2019, at 4:09 PM, Andrii Nakryiko <andrii.nakryiko@...il.com> wrote:
>
> On Mon, Jul 29, 2019 at 1:37 PM Song Liu <liu.song.a23@...il.com> wrote:
>>
>> On Mon, Jul 29, 2019 at 1:20 PM Song Liu <liu.song.a23@...il.com> wrote:
>>>
>>> On Wed, Jul 24, 2019 at 1:34 PM Andrii Nakryiko <andriin@...com> wrote:
>>>>
>>>> This patch set implements central part of CO-RE (Compile Once - Run
>>>> Everywhere, see [0] and [1] for slides and video): relocating field 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.
>>>> Patches #3-#10 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-2CO-RE relocations
>>>>
>>>> This patch set implements central part of CO-RE (Compile Once - Run
>>>> Everywhere, see [0] and [1] for slides and video): relocating field 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.
>>>> Patches #3-#10 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
>>>>
>>>> Andrii Nakryiko (10):
>>>> libbpf: add .BTF.ext offset relocation section loading
>>>> libbpf: implement BPF CO-RE offset relocation algorithm
>>>> 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
>>>> selftest/bpf: add CO-RE relocs ptr-as-array tests
>>>> selftests/bpf: add CO-RE relocs ints tests
>>>>
>>>> tools/lib/bpf/btf.c | 64 +-
>>>> tools/lib/bpf/btf.h | 4 +
>>>> tools/lib/bpf/libbpf.c | 866 +++++++++++++++++-
>>>> tools/lib/bpf/libbpf.h | 1 +
>>>> tools/lib/bpf/libbpf_internal.h | 91 ++
>>>> .../selftests/bpf/prog_tests/core_reloc.c | 363 ++++++++
>>>> .../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_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 | 642 +++++++++++++
>>>> .../bpf/progs/test_core_reloc_arrays.c | 58 ++
>>>> .../bpf/progs/test_core_reloc_flavors.c | 65 ++
>>>> .../bpf/progs/test_core_reloc_ints.c | 48 +
>>>> .../bpf/progs/test_core_reloc_kernel.c | 39 +
>>>> .../bpf/progs/test_core_reloc_mods.c | 68 ++
>>>> .../bpf/progs/test_core_reloc_nesting.c | 48 +
>>>> .../bpf/progs/test_core_reloc_primitives.c | 50 +
>>>> .../bpf/progs/test_core_reloc_ptr_as_arr.c | 34 +
>>>> 58 files changed, 2527 insertions(+), 47 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_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_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
>>>
>>> We have created a lot of small files. Would it be cleaner if we can
>>> somehow put these
>>> data in one file (maybe different sections?).
>>
>> After reading more, I guess you have tried this and end up with current
>> design: keep most struct defines in core_reloc_types.h.
>
> Yeah, I have all the definition in one header file, but then I need
> individual combinations as separate BTFs, so I essentially "pick"
> desired types using function declarations. Creating those BTFs by hand
> would be a nightmare to create and maintain.
>
>>
>>>
>>> Alternatively, maybe create a folder for these files:
>>> tools/testing/selftests/bpf/progs/core/
>>
>> I guess this would still make it cleaner.
>
> There is nothing too special about core tests to split them. Also it
> would require Makefile changes and would deviate test_progs
> definitions from analogous test_maps, test_verifier, test_btf, etc, so
> I'm not sure about that. I though about putting those btf__* files
> under separate directory, but I'm on the fence there as well, as I'd
> rather have related files to stay together...
>
I guess we can defer this decision to later. So I am OK with current
approach for now.
Thanks,
Song
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