linux-kernel - Re: [PATCH 2/2] parisc: fix module loading failure of large modules

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Date:	Mon, 29 Dec 2008 18:56:40 +0100
From:	Helge Deller <deller@....de>
To:	John David Anglin <dave@...uly1.hia.nrc.ca>
CC:	linux-parisc@...r.kernel.org, linux-kernel@...r.kernel.org,
	kyle@...artin.ca, randolph@...sq.org, jmm@...til.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	Helge Deller <deller@....de>
Subject: Re: [PATCH 2/2] parisc: fix module loading failure of large modules

John David Anglin wrote:
> Hi Helge,
> 
>> With this patch we now instead append individual PLT stub entries
>> directly at the end of the code sections where the stubs are actually
>> called. This reduces the distance between the PCREL location and the
>> stub entry so that the relocations can be fulfilled.
> 
> GCC for PA-RISC assumes that the stubs will be placed before the code
> section.  This is what HP-UX does.  It's also not possible to compute
> the distance to the end of a function in GCC due to the way branch
> shortening is done.  If the distance to the start of the code section
> is too large, GCC outputs a long call.

Interesting. I didn't knew that.

> If you can insert them before the code section where the stubs are
> called, this will minimize the chance that a pc-relative call will
> not reach its stub.

Yes, good idea.
I'll change that and send an updated patch.

> Great patch!

Thanks!

Helge
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