mbox series

[bpf-next,v3,00/10] Support BTF_KIND_TYPE_TAG for btf_type_tag attributes

Message ID 20211112012604.1504583-1-yhs@fb.com (mailing list archive)
Headers show
Series Support BTF_KIND_TYPE_TAG for btf_type_tag attributes | expand

Message

Yonghong Song Nov. 12, 2021, 1:26 a.m. UTC 
LLVM patches ([1] for clang, [2] and [3] for BPF backend)
added support for btf_type_tag attributes. This patch
added support for the kernel.

The main motivation for btf_type_tag is to bring kernel
annotations __user, __rcu etc. to btf. With such information
available in btf, bpf verifier can detect mis-usages
and reject the program. For example, for __user tagged pointer,
developers can then use proper helper like bpf_probe_read_kernel()
etc. to read the data.

BTF_KIND_TYPE_TAG may also useful for other tracing
facility where instead of to require user to specify
kernel/user address type, the kernel can detect it
by itself with btf.

Patch 1 added support in kernel, Patch 2 for libbpf and Patch 3
for bpftool. Patches 4-9 are for bpf selftests and Patch 10
updated docs/bpf/btf.rst file with new btf kind.

  [1] https://reviews.llvm.org/D111199
  [2] https://reviews.llvm.org/D113222
  [3] https://reviews.llvm.org/D113496

Changelogs:
  v2 -> v3:
    - rebase to resolve merge conflicts.
  v1 -> v2:
    - add more dedup tests.
    - remove build requirement for LLVM=1.
    - remove testing macro __has_attribute in bpf programs
      as it is always defined in recent clang compilers.

Yonghong Song (10):
  bpf: Support BTF_KIND_TYPE_TAG for btf_type_tag attributes
  libbpf: Support BTF_KIND_TYPE_TAG
  bpftool: Support BTF_KIND_TYPE_TAG
  selftests/bpf: Test libbpf API function btf__add_type_tag()
  selftests/bpf: Add BTF_KIND_TYPE_TAG unit tests
  selftests/bpf: Test BTF_KIND_DECL_TAG for deduplication
  selftests/bpf: Rename progs/tag.c to progs/btf_decl_tag.c
  selftests/bpf: Add a C test for btf_type_tag
  selftests/bpf: Clarify llvm dependency with btf_tag selftest
  docs/bpf: Update documentation for BTF_KIND_TYPE_TAG support

 Documentation/bpf/btf.rst                     |  13 +-
 include/uapi/linux/btf.h                      |   3 +-
 kernel/bpf/btf.c                              |  14 +-
 tools/bpf/bpftool/btf.c                       |   2 +
 tools/include/uapi/linux/btf.h                |   3 +-
 tools/lib/bpf/btf.c                           |  23 +++
 tools/lib/bpf/btf.h                           |   9 +-
 tools/lib/bpf/btf_dump.c                      |   9 +
 tools/lib/bpf/libbpf.c                        |  31 +++-
 tools/lib/bpf/libbpf.map                      |   1 +
 tools/lib/bpf/libbpf_internal.h               |   2 +
 tools/testing/selftests/bpf/README.rst        |   9 +-
 tools/testing/selftests/bpf/btf_helpers.c     |   4 +-
 tools/testing/selftests/bpf/prog_tests/btf.c  | 157 +++++++++++++++++-
 .../selftests/bpf/prog_tests/btf_tag.c        |  44 ++++-
 .../selftests/bpf/prog_tests/btf_write.c      |  67 +++++---
 .../bpf/progs/{tag.c => btf_decl_tag.c}       |   4 -
 .../selftests/bpf/progs/btf_type_tag.c        |  25 +++
 tools/testing/selftests/bpf/test_btf.h        |   3 +
 19 files changed, 370 insertions(+), 53 deletions(-)
 rename tools/testing/selftests/bpf/progs/{tag.c => btf_decl_tag.c} (94%)
 create mode 100644 tools/testing/selftests/bpf/progs/btf_type_tag.c

Comments

Alexei Starovoitov Nov. 12, 2021, 1:45 a.m. UTC | #1 
On Thu, Nov 11, 2021 at 5:26 PM Yonghong Song <yhs@fb.com> wrote:
>
> LLVM patches ([1] for clang, [2] and [3] for BPF backend)
> added support for btf_type_tag attributes. This patch
> added support for the kernel.
>
> The main motivation for btf_type_tag is to bring kernel
> annotations __user, __rcu etc. to btf. With such information
> available in btf, bpf verifier can detect mis-usages
> and reject the program. For example, for __user tagged pointer,
> developers can then use proper helper like bpf_probe_read_kernel()
> etc. to read the data.
>
> BTF_KIND_TYPE_TAG may also useful for other tracing
> facility where instead of to require user to specify
> kernel/user address type, the kernel can detect it
> by itself with btf.
>
> Patch 1 added support in kernel, Patch 2 for libbpf and Patch 3
> for bpftool. Patches 4-9 are for bpf selftests and Patch 10
> updated docs/bpf/btf.rst file with new btf kind.
>
>   [1] https://reviews.llvm.org/D111199
>   [2] https://reviews.llvm.org/D113222
>   [3] https://reviews.llvm.org/D113496
>
> Changelogs:
>   v2 -> v3:
>     - rebase to resolve merge conflicts.
>   v1 -> v2:
>     - add more dedup tests.
>     - remove build requirement for LLVM=1.
>     - remove testing macro __has_attribute in bpf programs
>       as it is always defined in recent clang compilers.

Applied. Thanks.
Cannot wait to get tags available in vmlinux.