Re: [PATCHv2] btf_encoder: Match ftrace addresses within elf functions

On February 17, 2021 10:40:43 AM GMT-03:00, Sedat Dilek [off-list ref] wrote:

On Wed, Feb 17, 2021 at 1:44 PM Arnaldo Carvalho de Melo
[off-list ref] wrote:

quoted

Em Sat, Feb 13, 2021 at 05:46:48PM +0100, Jiri Olsa escreveu:

quoted

Currently when processing DWARF function, we check its entrypoint
against ftrace addresses, assuming that the ftrace address matches
with function's entrypoint.

This is not the case on some architectures as reported by Nathan
when building kernel on arm [1].

Fixing the check to take into account the whole function not
just the entrypoint.

Most of the is_ftrace_func code was contributed by Andrii.

Applied locally, will go out after tests,

Hi Arnaldo,

Is it possible to have a pahole version 1.21 with this patch and the
one from Yonghong Son?

From my local pahole Git:

$ git log --oneline --no-merges v1.20..
2f83aefdbddf (for-1.20/btf_encoder-ftrace_elf-clang-jolsa-v2)
btf_encoder: Match ftrace addresses within elf functions
f21eafdfc877 (for-1.20/btf_encoder-sanitized_int-clang-yhs-v2)
btf_encoder: sanitize non-regular int base type

Both patches fixes all issues seen so far with LLVM/Clang >=
12.0.0-rc1 and DWARF-v5 and BTF (debug-info) and pahole on
Linux/x86_64 and according to Nathan on Linux/arm64.
Yesterday, I tried with LLVM/Clang 13-git from <apt.llvm.org>.

BTW, Nick's DWARF-v5 patches are pending in <kbuild.git#kbuild> (see
[1]).

Personally, I can wait until [1] is in Linus Git.

Please, let me/us know what you are planning.
( I know it is Linux v5.12 merge-window. )

Sure, next week.

- Arnaldo

Regards,
- Sedat -

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git/log/?h=kbuild

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