linux-mips
[Top] [All Lists]

Re: Relocation problem with MIPS kernel modules

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: Relocation problem with MIPS kernel modules
From: David VomLehn <dvomlehn@cisco.com>
Date: Mon, 3 Aug 2009 11:19:58 -0700
Authentication-results: sj-dkim-1; header.From=dvomlehn@cisco.com; dkim=pass ( sig from cisco.com/sjdkim1004 verified; );
Cc: GCC Help Mailing List <gcc-help@gcc.gnu.org>, Linux MIPS Mailing List <linux-mips@linux-mips.org>
Dkim-signature: v=1; a=rsa-sha256; q=dns/txt; l=1630; t=1249323598; x=1250187598; c=relaxed/simple; s=sjdkim1004; h=Content-Type:From:Subject:Content-Transfer-Encoding:MIME-Version; d=cisco.com; i=dvomlehn@cisco.com; z=From:=20David=20VomLehn=20<dvomlehn@cisco.com> |Subject:=20Re=3A=20Relocation=20problem=20with=20MIPS=20ke rnel=20modules |Sender:=20; bh=3C8FkEp8z1smxkIIQBRVbvhvmIWMqLZECLMFJs6HTUY=; b=uEDgULWT0+aYvLDz7aM8fMO2xlN3HoCpUjfCH4kdYYqqa6dUMua/h5l+X1 AkqcVd7Ysg4KfRak7lSe3ndeTcScWA77jPC+8AeOHGz55eOJQzXoVfig1OmZ 9MPUmT4z9AM0cit6sji79CJ94HoYpVxkgIwyPo2sU4m5cifxanOfQ=;
In-reply-to: <20090803092030.GB30431@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20090730184923.GA27030@cuplxvomd02.corp.sa.net> <20090803092030.GB30431@linux-mips.org>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.18 (2008-05-17)
On Mon, Aug 03, 2009 at 10:20:30AM +0100, Ralf Baechle wrote:
> On Thu, Jul 30, 2009 at 11:49:23AM -0700, David VomLehn wrote:
> 
> > To: GCC Help Mailing List <gcc-help@gcc.gnu.org>,
> >     Linux MIPS Mailing List <linux-mips@linux-mips.org>
> > Subject: Relocation problem with MIPS kernel modules
> > Content-Type: text/plain; charset=us-ascii
> > 
> > I have a MIPS loadable kernel module that, when I try to insmod it, causes 
> > the
> > kernel to emit the message:
> > 
> >     module xyz: dangerous relocation
...
> > According to the MIPS ABI, for what it's worth, "Each relocation type of
> > R_MIPS_HI16 must have an associated R_MIPS_LO16 entry immediately following
> > it in the list of relocations." So, what's actually getting generated by
> > gcc and linker differs from the closest thing we have to an ABI of record 
> > for
> > MIPS processors.
> 
> The GNU tools as an extension over the MIPS ABI allows an arbitrary number of
> R_MIPS_HI16 relocations to be followed by a R_MIPS_LO16 symbol.  All
> relocations of this sequence must use the same symbol, of course.  This is
> a very old extension; I think it predates the Linux/MIPS port.

Perhaps a foolish question, but is this documented anywhere? I know there is a
a document over at http://gcc.gnu.org/gcc-3.4/mips-abi.html addressing some
other MIPS ABI changes, but I didn't see this one. Obviously, we could put
documentation on the linux-mips Wiki, with pointers to other documents, but
I'm not sure this is the right place. I'm also concerned there could be other
ABI changes/extensions that need to be included.

>   Ralf

David

<Prev in Thread] Current Thread [Next in Thread>