From: Jan Kratochvil <jan.kratochvil@redhat.com>
To: David Gardner <daveg@xmos.com>
Cc: gdb@sourceware.org
Subject: Re: How to call functions which have ifunc symbols (e.g. strcmp) from inside gdb
Date: Thu, 02 Jun 2011 13:29:00 -0000 [thread overview]
Message-ID: <20110602132922.GA32664@host1.jankratochvil.net> (raw)
In-Reply-To: <20110602122944.GB30346@xmos.com>
On Thu, 02 Jun 2011 14:29:44 +0200, David Gardner wrote:
> Calling strcmp from inside gdb thusly:
>
> (gdb) call strcmp("foo", "foo")
> $3 = -146921376
>
> Gives unexpected values.
>
> I note that there is a bug for this already
> (http://sourceware.org/bugzilla/show_bug.cgi?id=12347) and this mentions
> that the strcmp symbol is the ifunc wrapper for the strcmp function, but
> this seems counter-intuitive for a user of gdb.
This is fixed in FSF GDB HEAD and GDB 7.3-prerelease branch.
[patch 0/7] STT_GNU_IFUNC support
http://sourceware.org/ml/gdb-patches/2011-03/msg00937.html
You can download a GDB snapshot before gdb-7.3 gets released these days/weeks.
http://www.gnu.org/software/gdb/current/
> Is there an alternative method of calling ifunc-enabled functions which
> can be used for calls (and related items such as conditional
> breakpoints) within gdb?
If you still have old GDB you can cast it yourself:
(gdb) p (*(int(*(*)())())strcmp)()("a","b")
$1 = -1
Regards,
Jan
next prev parent reply other threads:[~2011-06-02 13:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-02 12:30 David Gardner
2011-06-02 13:29 ` Jan Kratochvil [this message]
2011-06-06 21:23 ` Thiago Jung Bauermann
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