On 11/25/21 1:33 PM, Arnaldo Carvalho de Melo wrote:
Em Tue, Nov 23, 2021 at 08:49:17PM -0800, Andrii Nakryiko escreveu:
On Tue, Nov 23, 2021 at 3:36 PM Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
Em Tue, Nov 23, 2021 at 10:32:18AM -0800, Andrii Nakryiko escreveu:
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
To the next branch, and the libbpf pahole CI is failing, since a few
days, can you please take a look?
We've had Clang regression which Yonghong fixed very quickly, but then
we were blocked on Clang nightly builds being broken for days. Seems
like we got a new Clang today, so hopefully libbpf CI will be back to
green again.
It is back to green, so I moved next to master, i.e. this series is now
on master.
Arnaldo,
Is it possible that we could cut a pahole release in the near future?
My kernel using btf_type_tag patch ([1]) needs a pahole version check.
In old pahole versions, a warning about pointer type subtags not
supported will be emitted and btf_type_tag attributes (as pointer type
subtags) will be ignored.
[1] https://lore.kernel.org/bpf/20211118184810.1846996-1-yhs@xxxxxx/
Thanks!
- Arnaldo
super familiar with the DWARF loader parts, so I mostly just read it
very superficially :)
I replaced the patches that changed, re-added the S-o-B for Yonghong and
tested it with llvm-project HEAD.
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Adding it to the csets.
Thanks!
- Arnaldo
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
--
- Arnaldo
