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From: "tromey at sourceware dot org" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug win32/18027] dwarf2 debug info after rebasing DLLs unusable
Date: Mon, 13 Feb 2023 22:08:26 +0000 [thread overview]
Message-ID: <bug-18027-4717-XvWcwWrVJ7@http.sourceware.org/bugzilla/> (raw)
In-Reply-To: <bug-18027-4717@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=18027
--- Comment #11 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to Corinna Vinschen from comment #10)
> Indeed, this is not necessarily a GDB bug. Apologies, but 8 years ago
> it very much looked like a combined ld/GDB problem, that's why I created
> https://sourceware.org/bugzilla/show_bug.cgi?id=18025 and this bug here
> at the same time.
Completely understandable, no need to apologize :)
> In fact, the first question is probably if the dwarf2 info couldn't
> by imagebase-relative, rather than absolute. If that's possible
> (and maybe even already handled in GDB?) this could be done by tweaking
> the linker.
I think this would be better, but won't it cause issues if we then
use gdb to debug existing executables? Since those will have the
offsets already in the DWARF?
> ...then it would be great if GDB could workaround this somehow.
> The problem here is, I have no clue if there's anything in the DLL
> which would be indicative of the original image base address after
> rebasing. Unless, maybe, some of the dwarf2 info itself can be
> used to reconstruct the originl address?
binutils has a workaround based on _bfd_dwarf2_find_symbol_bias
(see bfd/dwarf2.c).
What this does is look for a function in the DWARF that has an address,
then tries to find that same function in the linker symbols. When
it finds a match, it uses those addresses to compute the delta.
This could work in gdb as well, it's just very unfortunate to have to do it.
However it's hard to see another way.
One idea I had is to assume that some function lives in the first text page
and try to use the lowest address seen (this is easier to get just from
scanning
the DWARF) to compute the offset, but this fails for cases like a DLL with
a mix of -g / no-g objects.
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next prev parent reply other threads:[~2023-02-13 22:08 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-26 5:36 [Bug win32/18027] New: " corinna at vinschen dot de
2015-02-26 9:39 ` [Bug win32/18027] " asmwarrior at gmail dot com
2023-02-11 17:48 ` tromey at sourceware dot org
2023-02-12 12:20 ` ssbssa at sourceware dot org
2023-02-13 10:31 ` corinna at vinschen dot de
2023-02-13 10:36 ` corinna at vinschen dot de
2023-02-13 14:01 ` simark at simark dot ca
2023-02-13 16:17 ` corinna at vinschen dot de
2023-02-13 17:13 ` simark at simark dot ca
2023-02-13 17:24 ` ssbssa at sourceware dot org
2023-02-13 19:23 ` tromey at sourceware dot org
2023-02-13 19:46 ` ssbssa at sourceware dot org
2023-02-13 19:48 ` corinna at vinschen dot de
2023-02-13 22:08 ` tromey at sourceware dot org [this message]
2023-02-15 10:22 ` corinna at vinschen dot de
2023-02-17 2:15 ` tromey at sourceware dot org
2023-02-28 14:43 ` tromey at sourceware dot org
2023-02-28 15:20 ` corinna at vinschen dot de
2023-02-28 15:22 ` corinna at vinschen dot de
2023-03-24 17:31 ` tromey at sourceware dot org
2023-03-24 19:00 ` corinna at vinschen dot de
2023-03-27 9:19 ` nickc at redhat dot com
2023-03-28 8:58 ` corinna at vinschen dot de
2023-03-28 14:01 ` nickc at redhat dot com
2023-03-28 18:10 ` corinna at vinschen dot de
2023-03-29 12:46 ` tromey at sourceware dot org
2023-03-30 9:23 ` corinna at vinschen dot de
2023-03-30 9:24 ` corinna at vinschen dot de
2023-04-21 16:38 ` tromey at sourceware dot org
2023-04-21 16:54 ` tromey at sourceware dot org
2023-04-21 17:11 ` tromey at sourceware dot org
2023-04-21 19:48 ` corinna at vinschen dot de
2023-04-24 15:54 ` tromey at sourceware dot org
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