linux-kernel - Re: module version magic and arches with symbol prefixes

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Message-ID: <200906290807.35473.rgetz@blackfin.uclinux.org>
Date:	Mon, 29 Jun 2009 08:07:35 -0400
From:	Robin Getz <rgetz@...ckfin.uclinux.org>
To:	"Rusty Russell" <rusty@...tcorp.com.au>
CC:	"Mike Frysinger" <vapier.adi@...il.com>,
	"Linux kernel mailing list" <linux-kernel@...r.kernel.org>
Subject: Re: module version magic and arches with symbol prefixes

On Tue 23 Jun 2009 03:07, Rusty Russell pondered:
> On Sat, 20 Jun 2009 02:37:45 am Robin Getz wrote:
> > On Fri 19 Jun 2009 09:14, Mike Frysinger pondered:
> > > On Fri, Jun 19, 2009 at 08:54, Robin Getz wrote:
> > > > On Fri 19 Jun 2009 01:38, Rusty Russell pondered:
> > > >> No, it means the kernel didn't build properly.
> > > >
> > > > Or a module didn't build properly.
> > >
> > > nah, when i talked to you earlier i was wrong -- this find_symbol() is
> > > looking up the symbol in the kernel, not in the module.  the lookup of
> > > the symbol in the requested module actually works.
> >
> > OK - Yeah, I see it now in the kernel proper. (sorry for the noise)
> >
> > Wouldn't it make sense to move this somewhere else then? and add a
> > __initcall() for it? We should only need to check for it once - it would
> > make things insignificantly faster, and smaller :)
> 
> Patch welcome.

I looked at this:

> static inline int check_modstruct_version(Elf_Shdr *sechdrs,
>                                           unsigned int versindex,
>                                           struct module *mod)
> {
>         const unsigned long *crc;
>
>         if (!find_symbol(MODULE_SYMBOL_PREFIX "module_layout", NULL,
>                          &crc, true, false))
>                 BUG();
>         return check_version(sechdrs, versindex, "module_layout", mod, crc); }

and then decided that since you need to call find_symbol() to populate 
the crc, before it is used in check_version(), you might as well leave
alone (it wouldn't result in any smaller/faster code)...

So, I didn't send anything...
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