On Tue, Sep 14, 2021 at 3:30 PM Yonghong Song <yhs@xxxxxx> wrote:
>
> LLVM14 added support for a new C attribute ([1])
> __attribute__((btf_tag("arbitrary_str")))
> This attribute will be emitted to dwarf ([2]) and pahole
> will convert it to BTF. Or for bpf target, this
> attribute will be emitted to BTF directly ([3], [4]).
> The attribute is intended to provide additional
> information for
> - struct/union type or struct/union member
> - static/global variables
> - static/global function or function parameter.
>
> For linux kernel, the btf_tag can be applied
> in various places to specify user pointer,
> function pre- or post- condition, function
> allow/deny in certain context, etc. Such information
> will be encoded in vmlinux BTF and can be used
> by verifier.
>
> The btf_tag can also be applied to bpf programs
> to help global verifiable functions, e.g.,
> specifying preconditions, etc.
>
> This patch added basic parsing and checking support
> in kernel for new BTF_KIND_TAG kind.
>
> [1] https://reviews.llvm.org/D106614
> [2] https://reviews.llvm.org/D106621
> [3] https://reviews.llvm.org/D106622
> [4] https://reviews.llvm.org/D109560
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
LGTM.
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> include/uapi/linux/btf.h | 14 +++-
> kernel/bpf/btf.c | 128 +++++++++++++++++++++++++++++++++
> tools/include/uapi/linux/btf.h | 14 +++-
> 3 files changed, 154 insertions(+), 2 deletions(-)
>
[...]
