From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Cc: dwarves@vger.kernel.org, elfutils-devel@sourceware.org, mark@klomp.org
Subject: Re: Porting pahole from dwarf_next_unit() to dwarf_get_units()
Date: Tue, 5 Dec 2023 12:47:52 -0300 [thread overview]
Message-ID: <ZW9GKNPpEU1M3vYp@kernel.org> (raw)
In-Reply-To: <CADWks+b06hpoBJpVdtd4HXdC0w24hObq0WOGCdfMGkpC7k=2vQ@mail.gmail.com>
Em Tue, Dec 05, 2023 at 01:03:01PM +0000, Dimitri John Ledkov escreveu:
> Currently pahole warns and does nothing upon hitting
> DW_TAG_skeleton_unit as implemented at
> https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=0135ccd632796ab3aff65b7c99b374c4682c2bcf
>
> In elfutils, a while back a new API got added that aids with discovery
> and processing of such tags -
> https://sourceware.org/git/?p=elfutils.git;a=commitdiff;h=79f0e623dcde4b042bb72f636a2211d67d5c0ade
>
> It seems to me if pahole is ported from using dwarf_next_unit() to
> instead use dwarf_get_units() native support can be added for
> split-dwarf (dwo) files.
That would be awesome!
> I am trying to write such a port, but it is proving to be very
> difficult.
I did some work on supporting split-dwarf months ago, but got
sidetracked with other work, BTF related and then the code bitrotted, I
have to go back looking at it to swap back the details into my brain:
https://git.kernel.org/pub/scm/devel/pahole/pahole.git/log/?h=alt_dwarf
The patches after:
45c044860c2abce7 dwarf_loader: Sync with LINUX_ELFNOTE_LTO_INFO macro from kernel
Are the ones to suport alt dwarf.
> I am entirely unfamiliar with neither pahole nor libdw nor
> the dwarf file format. Thus it is very confusing when both pahole and
> dwarf library use very similar type names and structs. For example
> libdw has struct Dwarf_CU and pahole has unrelated dwarf_cu struct.
> What are the differences between dwarf_nextcu(), dwarf_next_unit(),
> dwarf_get_units() and when should one use each one of them? (or nest
> them?)
> Is a port of https://git.kernel.org/pub/scm/devel/pahole/pahole.git/tree/dwarf_loader.c?id=0135ccd632796ab3aff65b7c99b374c4682c2bcf
> to use dwarf_get_units() a right approach and would be welcomed?
Yes, we need to support DWARF5 fully.
> Is anyone else interested in providing any help, or guidance?
I'm interested, and I think if Mark could help it would be great as
well.
- ARnaldo
next prev parent reply other threads:[~2023-12-05 15:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-05 13:03 Dimitri John Ledkov
2023-12-05 15:47 ` Arnaldo Carvalho de Melo [this message]
2023-12-05 16:11 ` Dimitri John Ledkov
2023-12-05 18:46 ` Arnaldo Carvalho de Melo
2024-01-14 22:29 ` Mark Wielaard
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZW9GKNPpEU1M3vYp@kernel.org \
--to=acme@kernel.org \
--cc=dimitri.ledkov@canonical.com \
--cc=dwarves@vger.kernel.org \
--cc=elfutils-devel@sourceware.org \
--cc=mark@klomp.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).