From: Anton Blanchard <anton@samba.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Paul Mackerras <paulus@samba.org>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
emunson@mgebm.net, linux-kernel@vger.kernel.org,
amodra@gmail.com
Subject: Re: [PATCH] perf: Fix symbol resolution on old ppc64 ABI
Date: Mon, 25 Jul 2011 20:48:59 +1000 [thread overview]
Message-ID: <20110725204859.51e50611@kryten> (raw)
In-Reply-To: <20110725062542.GA694@elte.hu>
Hi Ingo,
> > The synthetic symbol creation code has an issue with the old ppc64
> > ABI. We end up with duplicate symbols of different sizes that
> > overlap.
> >
> > To fix this, walk all of the symbols and remove any duplicates that
> > are the length of a function descriptor.
>
> > I'd prefer not to add a ppc64 specific hack here, but I'm not sure
> > how we can fix this in a simpler way.
>
> Symbol space problems are common on other architectures as well.
>
> We could use a heuristic: when symbols are overlapping then we could
> throw away the one that is smaller. This would implicitly cover the
> ppc64 case, right?
>
> I'd also suggest we warn somewhere that a symbol has been thrown
> away, if verbosity is turned off. (i.e. don't warn by default.)
It would cover most cases. There would be an issue with functions that
are less than 24 bytes in length (ie 6 instructions). Tiny functions
are probably rare enough that we can live with it.
Anton
next prev parent reply other threads:[~2011-07-25 10:49 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-25 4:23 [PATCH] perf: Fix symbol resolution on old ppc64 ABI Anton Blanchard
2011-07-25 6:25 ` Ingo Molnar
2011-07-25 10:48 ` Anton Blanchard [this message]
2011-07-25 10:50 ` Ingo Molnar
2011-07-25 12:32 ` Anton Blanchard
2011-07-25 12:36 ` Ingo Molnar
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=20110725204859.51e50611@kryten \
--to=anton@samba.org \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@ghostprotocols.net \
--cc=amodra@gmail.com \
--cc=emunson@mgebm.net \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=paulus@samba.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.