On Mon, Nov 22, 2021 at 8:56 PM Yonghong Song <yhs@xxxxxx> wrote:
>
> btf_type_tag is a new llvm type attribute which is used similar
> to kernel __user/__rcu attributes. The format of btf_type_tag looks like
> __attribute__((btf_type_tag("tag1")))
> For the case where the attribute applied to a pointee like
> #define __tag1 __attribute__((btf_type_tag("tag1")))
> #define __tag2 __attribute__((btf_type_tag("tag2")))
> int __tag1 * __tag1 __tag2 *g;
> the information will be encoded in dwarf.
>
> In BTF, the attribute is encoded as a new kind
> BTF_KIND_TYPE_TAG and latest bpf-next supports it.
>
> The patch added support in pahole, specifically
> converts llvm dwarf btf_type_tag attributes to
> BTF types. Please see individual patches for details.
>
> Changelog:
> v1 -> v2:
> - reorg an if condition to reduce nesting level.
> - add more comments to explain how to chain type tag types.
>
> Yonghong Song (4):
> libbpf: sync with latest libbpf repo
> dutil: move DW_TAG_LLVM_annotation definition to dutil.h
> dwarf_loader: support btf_type_tag attribute
> btf_encoder: support btf_type_tag attribute
>
I thought that v1 was already applied, but either way LGTM. I'm not
super familiar with the DWARF loader parts, so I mostly just read it
very superficially :)
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> btf_encoder.c | 7 +++
> dutil.h | 4 ++
> dwarf_loader.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++---
> dwarves.h | 38 +++++++++++++-
> lib/bpf | 2 +-
> pahole.c | 8 +++
> 6 files changed, 190 insertions(+), 9 deletions(-)
>
> --
> 2.30.2
>
