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Message-ID: <CAEf4BzbKYi53TdF9nAB3i3gAuca8FjM_P3F5aHp1uQ6coMgZ9A@mail.gmail.com>
Date: Mon, 29 Jul 2019 16:09:59 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Song Liu <liu.song.a23@...il.com>
Cc: 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 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...
>
> Thanks,
> Song
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